Science.gov

Sample records for partial molar volume

  1. The partial molar volume of carbon dioxide in peridotite partial melt at high pressure

    NASA Astrophysics Data System (ADS)

    Duncan, Megan S.; Agee, Carl B.

    2011-12-01

    The partial molar volume of CO 2 ( V) in silicate melt was determined for a komatiite composition using high pressure sink/float experiments in a multi-anvil press. The density of the experimental melt at pressure was determined by observing sinking and floating of pure forsterite (Fo100) and forsterite (Fo90) buoyancy markers. Values for V were bracketed at 4.3 GPa (23.71 cm 3/mol) and at 5.5 GPa (22.06 cm 3/mol), normalized to 2123 K. Combining the current data with previous work we now more accurately constrain the compression curve of V over the pressure range of 1.0 10 - 4 to 20 GPa. These data allow the calculation of density at pressure of carbonated silicate melts, such as kimberlite and silica undersaturated alkali basalts, and the determination of their buoyancy and eruptibility.

  2. Compositional dependent partial molar volume and compressibility of CO2 in rhyolite, phonolite and basalt glasses

    NASA Astrophysics Data System (ADS)

    Lerch, P.; Seifert, R.; Malfait, W. J.; Sanchez-Valle, C.

    2012-12-01

    Carbon dioxide is the second most abundant volatile in magmatic systems and plays an important role in many magmatic processes, e.g. partial melting, volatile saturation, outgassing. Despite this relevance, the volumetric properties of carbon-bearing silicates at relevant pressure and temperature conditions remain largely unknown because of considerable experimental difficulties associated with in situ measurements. Density and elasticity measurements on quenched glasses can provide an alternative source of information. For dissolved water, such measurements indicate that the partial molar volume is independent of compositions at ambient pressure [1], but the partial molar compressibility is not [2, 3]. Thus the partial molar volume of water may depend on melt composition at elevated pressure. For dissolved CO2, no such data is available. In order to constrain the effect of magma composition on the partial molar volume and compressibility of dissolved carbon, we determined the density and elasticity for three series of carbon-bearing basalt, phonolite and rhyolite glasses, quenched from 3.5 GPa and relaxed at ambient pressure. The CO2 content varies between 0 to 3.90 wt% depending on the glass composition. Glass densities were determined using the sink/float method in a diiodomethane (CH2I2) - acetone mixture. Brillouin measurements were conducted on relaxed and unrelaxed silicate glasses in platelet geometry to determine the compressional (VP) and shear (VS) wave velocities and elastic moduli. The partial molar volume of CO2 in rhyolite, phonolite and basalt glasses is 25.4 ± 0.9, 22.1 ± 0.6 and 26.6 ±1.8 cm3/mol, respectively. Thus, unlike for dissolved water, the partial molar volume of CO2 displays a resolvable compositional effect. Although the composition and CO2/carbonate speciation of the phonolite glasses is intermediate between that of the rhyolite and basalt glasses, the molar volume is not. Similar to dissolved water, the partial molar bulk modulus of CO2 displays a strong compositional effect. If these compositional dependencies persist in the analogue melts, the partial molar volume of dissolved CO2 will depend on melt composition, both at low and elevated pressure. Thus, for CO2-bearing melts, a full quantitative understanding of density dependent magmatic processes, such as crystal fractionation, magma mixing and melt extraction will require in situ measurements for a range of melt compositions. [1] Richet, P. et al., 2000, Contrib Mineral Petrol, 138, 337-347. [2] Malfait et al. 2011, Am. Mineral. 96, 1402-1409. [3] Whittington et al., 2012, Am. Mineral. 97, 455-467.

  3. Note: Nonpolar solute partial molar volume response to attractive interactions with water

    SciTech Connect

    Williams, Steven M.; Ashbaugh, Henry S.

    2014-01-07

    The impact of attractive interactions on the partial molar volumes of methane-like solutes in water is characterized using molecular simulations. Attractions account for a significant 20% volume drop between a repulsive Weeks-Chandler-Andersen and full Lennard-Jones description of methane interactions. The response of the volume to interaction perturbations is characterized by linear fits to our simulations and a rigorous statistical thermodynamic expression for the derivative of the volume to increasing attractions. While a weak non-linear response is observed, an average effective slope accurately captures the volume decrease. This response, however, is anticipated to become more non-linear with increasing solute size.

  4. Hydrophobic hydration and the anomalous partial molar volumes in ethanol-water mixtures

    NASA Astrophysics Data System (ADS)

    Tan, Ming-Liang; Miller, Benjamin T.; Te, Jerez; Cendagorta, Joseph R.; Brooks, Bernard R.; Ichiye, Toshiko

    2015-02-01

    The anomalous behavior in the partial molar volumes of ethanol-water mixtures at low concentrations of ethanol is studied using molecular dynamics simulations. Previous work indicates that the striking minimum in the partial molar volume of ethanol VE as a function of ethanol mole fraction XE is determined mainly by water-water interactions. These results were based on simulations that used one water model for the solute-water interactions but two different water models for the water-water interactions. This is confirmed here by using two more water models for the water-water interactions. Furthermore, the previous work indicates that the initial decrease is caused by association of the hydration shells of the hydrocarbon tails, and the minimum occurs at the concentration where all of the hydration shells are touching each other. Thus, the characteristics of the hydration of the tail that cause the decrease and the features of the water models that reproduce this type of hydration are also examined here. The results show that a single-site multipole water model with a charge distribution that mimics the large quadrupole and the p-orbital type electron density out of the molecular plane has "brittle" hydration with hydrogen bonds that break as the tails touch, which reproduces the deep minimum. However, water models with more typical site representations with partial charges lead to flexible hydration that tends to stay intact, which produces a shallow minimum. Thus, brittle hydration may play an essential role in hydrophobic association in water.

  5. Hydrophobic hydration and the anomalous partial molar volumes in ethanol-water mixtures.

    PubMed

    Tan, Ming-Liang; Miller, Benjamin T; Te, Jerez; Cendagorta, Joseph R; Brooks, Bernard R; Ichiye, Toshiko

    2015-02-14

    The anomalous behavior in the partial molar volumes of ethanol-water mixtures at low concentrations of ethanol is studied using molecular dynamics simulations. Previous work indicates that the striking minimum in the partial molar volume of ethanol VE as a function of ethanol mole fraction XE is determined mainly by water-water interactions. These results were based on simulations that used one water model for the solute-water interactions but two different water models for the water-water interactions. This is confirmed here by using two more water models for the water-water interactions. Furthermore, the previous work indicates that the initial decrease is caused by association of the hydration shells of the hydrocarbon tails, and the minimum occurs at the concentration where all of the hydration shells are touching each other. Thus, the characteristics of the hydration of the tail that cause the decrease and the features of the water models that reproduce this type of hydration are also examined here. The results show that a single-site multipole water model with a charge distribution that mimics the large quadrupole and the p-orbital type electron density out of the molecular plane has "brittle" hydration with hydrogen bonds that break as the tails touch, which reproduces the deep minimum. However, water models with more typical site representations with partial charges lead to flexible hydration that tends to stay intact, which produces a shallow minimum. Thus, brittle hydration may play an essential role in hydrophobic association in water. PMID:25681917

  6. Hydrophobic hydration and the anomalous partial molar volumes in ethanol-water mixtures

    SciTech Connect

    Tan, Ming-Liang; Te, Jerez; Cendagorta, Joseph R.; Miller, Benjamin T.; Brooks, Bernard R.; Ichiye, Toshiko

    2015-02-14

    The anomalous behavior in the partial molar volumes of ethanol-water mixtures at low concentrations of ethanol is studied using molecular dynamics simulations. Previous work indicates that the striking minimum in the partial molar volume of ethanol V{sub E} as a function of ethanol mole fraction X{sub E} is determined mainly by water-water interactions. These results were based on simulations that used one water model for the solute-water interactions but two different water models for the water-water interactions. This is confirmed here by using two more water models for the water-water interactions. Furthermore, the previous work indicates that the initial decrease is caused by association of the hydration shells of the hydrocarbon tails, and the minimum occurs at the concentration where all of the hydration shells are touching each other. Thus, the characteristics of the hydration of the tail that cause the decrease and the features of the water models that reproduce this type of hydration are also examined here. The results show that a single-site multipole water model with a charge distribution that mimics the large quadrupole and the p-orbital type electron density out of the molecular plane has “brittle” hydration with hydrogen bonds that break as the tails touch, which reproduces the deep minimum. However, water models with more typical site representations with partial charges lead to flexible hydration that tends to stay intact, which produces a shallow minimum. Thus, brittle hydration may play an essential role in hydrophobic association in water.

  7. Infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide.

    PubMed

    Kong, Chang Yi; Siratori, Tomoya; Funazukuri, Toshitaka; Wang, Guosheng

    2014-10-01

    The effects of temperature and density on retention of platinum(II) 2,4-pentanedionate in supercritical fluid chromatography were investigated at temperatures of 308.15-343.15K and pressure range from 8 to 40MPa by the chromatographic impulse response method with curve fitting. The retention factors were utilized to derive the infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide. The determined partial molar volumes were small and positive at high pressures but exhibited very large and negative values in the highly compressible near critical region of carbon dioxide. PMID:25169720

  8. Partial molar volumes and viscous properties of glycine-aqueous urea solutions at 298.15 K

    NASA Astrophysics Data System (ADS)

    Deosarkar, S. D.; Ban, A. R.; Tawde, P. D.; Sawale, R. T.

    2015-07-01

    Density (ρ) and viscosity (η) of glycine ( c = 0.02-0.22 mol dm-3) in aqueous urea ( c = 0.5, 1.5, and 3.0 mol dm-3) solutions were measured at 298.15 K. Experimental density data has been used to calculate apparent molar volumes (φv) of glycine in aqueous and aqueous-urea solutions at 298.15 K. The dependence of apparent molar volumes on concentration of glycine was fitted to the Massons relation and apparent molar volume of glycine at infinite dilution (partial molar volume, φ{v/0}) was determined graphically. The partial molar volumes of transfer (Δtrφ{v/0}) of glycine at infinite dilution from pure water to aqueous-urea solutions at 298.15 K were calculated and interpreted in terms of various interactions and structural fittings in studied solutions. The relative viscosity data has been analyzed by Jones-Dole relation and viscosity B-coefficients were determined graphically. Viscosity B-coefficient of transfer (Δ B) was also calculated and compared with Δtrφ{v/0}.

  9. Fast Computation of Solvation Free Energies with Molecular Density Functional Theory: Thermodynamic-Ensemble Partial Molar Volume Corrections.

    PubMed

    Sergiievskyi, Volodymyr P; Jeanmairet, Guillaume; Levesque, Maximilien; Borgis, Daniel

    2014-06-01

    Molecular density functional theory (MDFT) offers an efficient implicit-solvent method to estimate molecule solvation free-energies, whereas conserving a fully molecular representation of the solvent. Even within a second-order approximation for the free-energy functional, the so-called homogeneous reference fluid approximation, we show that the hydration free-energies computed for a data set of 500 organic compounds are of similar quality as those obtained from molecular dynamics free-energy perturbation simulations, with a computer cost reduced by 2-3 orders of magnitude. This requires to introduce the proper partial volume correction to transform the results from the grand canonical to the isobaric-isotherm ensemble that is pertinent to experiments. We show that this correction can be extended to 3D-RISM calculations, giving a sound theoretical justification to empirical partial molar volume corrections that have been proposed recently. PMID:26273876

  10. Partial molar volumes and viscosities of aqueous hippuric acid solutions containing LiCl and MnCl2 4H2O at 303.15 K

    NASA Astrophysics Data System (ADS)

    Deosarkar, S. D.; Tawde, P. D.; Zinjade, A. B.; Shaikh, A. I.

    2015-09-01

    Density (?) and viscosity (?) of aqueous hippuric acid (HA) solutions containing LiCl and MnCl2 4H2O have been studied at 303.15 K in order to understand volumetric and viscometric behavior of these systems. Apparent molar volume (?v) of salts were calculated from density data and fitted to Massons relation and partial molar volumes (?{v/0}) at infinite dilution were determined. Relative viscosity data has been used to determine viscosity A and B coefficients using Jones-Dole relation. Partial molar volume and viscosity coefficients have been discussed in terms of ion-solvent interactions and overall structural fittings in solution.

  11. Partial Molar Volume of CO2 in Peridotitic Melt at High Pressure and Applications to Melt Mobility in the Mantle

    NASA Astrophysics Data System (ADS)

    Duncan, M. S.; Agee, C. B.

    2009-12-01

    The partial molar volume of CO2 (VCO2) is a quantity that may be used for elucidating the role of volatiles in silicate melt at high pressure, such as magma mobility during mantle differentiation when CO2 is present. Because CO2 tends to decrease silicate melt density, its presence should cause crystal-liquid density crossovers to occur at higher pressures than for non-carbonated silicate melts with the same major element composition. Experimental data presented here are crucial to understanding the driving force of carbonated magma eruption, such as kimberlite and nephelinite, especially in the pressure range of 0-3 GPa where extreme changes are observed in the compressibility and solubility of CO2 in peridotite partial melt.High pressure, sink/float experiments were conducted on a synthetic peridotite composition with ~5 wt.% CO2 added as CaCO3 (DG-5), and no CO2 added (DG-N). The mixtures were placed in Mo capsules with two synthetic forsterite spheres or two San Carlos spheres near the top and bottom of the capsule. Experiments were run in a Walker style multi-anvil using 8 mm TEL.Using the known compressibility of the spheres, the density (ρ) of each melt was determined at neutral buoyancy pressures and temperatures using the third order Birch-Murnaghan EOS. The forsterite crossover occurred at 4.6 GPa for DG-5 (ρ=3.14 g/cm3), and 4.0 GPa for DG-N (ρ=3.12 g/cm3). The San Carlos crossover occurred at 6.1 GPa for DG-5 (ρ=3.29 g/cm3), and ~5.0 GPa for DG-N (ρ=3.26 g/cm3).The VCO2 was determined using a modified version of the Bottinga and Weill (1970) equation: ρ=Σ XiMi / XiVi, the calculated ρ, the analyzed compositions, and the assumption that CO2 remained in the melt during sink/float. Preliminary values for VCO2 are 25.35 cm3/mol at 4.3 GPa and 22.92 cm3/mol at 5.6 GPa, both corrected to 1850°C. Based on the VCO2 at 1 bar (Liu & Lange, 2003) and at 19.5 GPa (Ghosh et al., 2007), the compressibility curve for CO2 may now be better constrained. The calculated curve shows a rapid decrease in VCO2 at low pressures indicating a high compressibility in the upper mantle.Currently, we are exploring electron microprobe and FTIR transmission and reflectance methods to better quantify the CO2 in our experimental run products which contain quench crystals and small pockets of glass. We believe the assumption that CO2 remains in the melt during sink/float experiment is valid because crossover positions differ between the DG-5 and DG-N samples. However, we are investigating this assumption because CO32-, CO2 and CO are not observed in the run products with FTIR transmission and reflectance, and the microprobe results for C are ambiguous. There are several possibilities that we are testing at this time.

  12. Variation and decomposition of the partial molar volume of small gas molecules in different organic solvents derived from molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Klhn, Marco; Martin, Alistair; Cheong, Daniel W.; Garland, Marc V.

    2013-12-01

    The partial molar volumes, bar V_i, of the gas solutes H2, CO, and CO2, solvated in acetone, methanol, heptane, and diethylether are determined computationally in the limit of infinite dilution and standard conditions. Solutions are described with molecular dynamics simulations in combination with the OPLS-aa force field for solvents and customized force field for solutes. bar V_i is determined with the direct method, while the composition of bar V_i is studied with Kirkwood-Buff integrals (KBIs). Subsequently, the amount of unoccupied space and size of pre-formed cavities in pure solvents is determined. Additionally, the shape of individual solvent cages is analyzed. Calculated bar V_i deviate only 3.4 cm3 mol-1 (7.1%) from experimental literature values. Experimental bar V_i variations across solutions are reproduced qualitatively and also quantitatively in most cases. The KBI analysis identifies differences in solute induced solvent reorganization in the immediate vicinity of H2 (<0.7 nm) and solvent reorganization up to the third solvation shell of CO and CO2 (<1.6 nm) as the origin of bar V_i variations. In all solutions, larger bar V_i are found in solvents that exhibit weak internal interactions, low cohesive energy density and large compressibility. Weak internal interactions facilitate solvent displacement by thermal solute movement, which enhances the size of solvent cages and thus bar V_i. Additionally, attractive electrostatic interactions of CO2 and the solvents, which do not depend on internal solvent interactions only, partially reversed the bar V_i trends observed in H2 and CO solutions where electrostatic interactions with the solvents are absent. More empty space and larger pre-formed cavities are found in solvents with weak internal interactions, however, no evidence is found that solutes in any considered solvent are accommodated in pre-formed cavities. Individual solvent cages are found to be elongated in the negative direction of solute movement. This wake behind the moving solute is more pronounced in case of mobile H2 and in solvents with weaker internal interactions. However, deviations from a spherical solvent cage shape do not influence solute-solvent radial distribution functions after averaging over all solvent cage orientations and hence do not change bar V_i. Overall, the applied methodology reproduces bar V_i and its variations reliably and the used bar V_i decompositions identify the underlying reasons behind observed bar V_i variations.

  13. Gingival enlargement associated with a partially erupted mandibular molar.

    PubMed

    Flaitz, C M

    2001-01-01

    Odontogenic lesions may present as enlarged opercula and result in the delayed eruption of teeth. This case report describes the clinical and microscopic features of a peripheral odontogenic fibroma in a 13-year-old boy that involved the overlying gingiva of a partially erupted, mandibular second molar. A differential diagnosis and treatment for lesions presenting as gingival enlargements in the molar region are discussed. PMID:11699171

  14. Melt densities in the CaO-FeO-Fe 2O 3-SiO 2 system and the compositional dependence of the partial molar volume of ferric iron in silicate melts

    NASA Astrophysics Data System (ADS)

    Dingwell, Donald B.; Brearley, Mark

    1988-12-01

    The densities of 10 melts in the CaO-FeO-Fe 2O 3-SiO 2 system were determined in equilibrium with air, in the temperature range of 1200 to 1550C, using the double-bob Archimedean technique. Melt compositions range from 6 to 58 wt% SiO 2, 14 to 76 wt% Fe 2O 3 and 10 to 46 wt% CaO. The ferric-ferrous ratios of glasses drop-quenched from loop fusion equilibration experiments were determined by 57Fe Mssbauer spectroscopy. Melt densities range from 2.689 to 3.618 gm/cm 3 with a mean standard deviation from replicate experiments of 0.15%. Least-squares regressions of molar volume versus molar composition have been performed and the root mean squared deviation shows that a linear combination of partial molar volumes for the oxide components (CaO, FeO, Fe 2O 3 and SiO 2) cannot describe the data set within experimental error. Instead, the inclusion of excess terms in CaFe 3+ and CaSi (product terms using the oxides) is required to yield a fit that describes the experimental data within error. The nonlinear compositional-dependence of the molar volumes of melts in this system can be explained by structural considerations of the roles of Ca and Fe 3+. The volume behavior of melts in this system is significantly different from that in the Na 2O-FeO-Fe 2O 3-SiO 2 system, consistent with the proposal that a proportion of Fe 3+ in melts in the CaO-FeO-Fe 2O 3-SiO 2 system is not tetrahedrally-coordinated by oxygen, which is supported by differences in 57Fe Mssbauer spectra of glasses. Specifically, this study confirms that the 57Fe Mssbauer spectra exhibit an area asymmetry and higher values of isomer shift of the ferric doublet that vary systematically with composition and temperature (this study; Dingwell and Virgo, 1987, 1988). These observations are consistent with a number of other lines of evidence ( e.g., homogeneous redox equilibria, Dickenson and Hess, 1986; viscosity, Dingwell and Virgo, 1987,1988). Two species of ferric iron, varying in proportions with temperature, composition and redox state, are sufficient to describe the above observations. The presence of more than one coordination geometry for Fe 3+ in low pressure silicate melts has several implications for igneous petrogenesis. The possible effects on compressibility, the pressure dependence of the redox ratio, and redox enthalpy are briefly noted.

  15. Oxygen from Hydrogen Peroxide. A Safe Molar Volume-Molar Mass Experiment.

    ERIC Educational Resources Information Center

    Bedenbaugh, John H.; And Others

    1988-01-01

    Describes a molar volume-molar mass experiment for use in general chemistry laboratories. Gives background technical information, procedures for the titration of aqueous hydrogen peroxide with standard potassium permanganate and catalytic decomposition of hydrogen peroxide to produce oxygen, and a discussion of the results obtained in three…

  16. Oxygen from Hydrogen Peroxide. A Safe Molar Volume-Molar Mass Experiment.

    ERIC Educational Resources Information Center

    Bedenbaugh, John H.; And Others

    1988-01-01

    Describes a molar volume-molar mass experiment for use in general chemistry laboratories. Gives background technical information, procedures for the titration of aqueous hydrogen peroxide with standard potassium permanganate and catalytic decomposition of hydrogen peroxide to produce oxygen, and a discussion of the results obtained in three

  17. Density and sound speed measurements on model basalt (An-Di-Hd) liquids at one bar: New constraints on the partial molar volume and compressibility of the FeO component

    NASA Astrophysics Data System (ADS)

    Guo, Xuan; Lange, Rebecca A.; Ai, Yuhui

    2014-02-01

    Density and sound speed measurements were obtained over a wide range of temperature for three model basalt liquids in the An-Di-Hd (CaAl2Si2O8-CaMgSi2O6-CaFeSi2O6) system. High-temperature (1585-1838 K) double-bob density measurements were combined with low-temperature (943-930 K) measurements at the limiting fictive temperature for each sample to provide liquid volume data over a temperature interval of ?900 K. In addition, relaxed sound speeds were obtained with a frequency sweep acoustic interferometer from 1665-1876 K. An ideal mixing model for molar volume, thermal expansivity, and isothermal compressibility recovers the new data from this study and leads to the following fitted values (2?) at 1723 K for VbarFeO (12.860.32 cm/mol), ?VbarFeO/?T((3.691.16)10-3 cm/mol-K) and ?barT,FeO((4.720.46)10-2 GPa). These volumetric properties for the FeO component are estimated to reflect Fe2+ in an average coordination of 5.7 (0.2), based on the relationship between VbarFeO and Fe2+ coordination derived by a comparison to mineral molar volumes (Guo et al., 2013). Application of these volumetric data to a calculation of the pressure dependence of the Fe-Mg exchange reaction between orthopyroxene and basaltic liquid results in a small decrease in Fe-MgKD with pressure. In contrast, partial melting experiments of peridotite show a small increase in Fe-MgKD(opx-liq) with pressure (e.g., Walter, 1998). This difference in the pressure dependence is proposed to reflect the role of alkalis in reducing the average coordination number of Fe2+ toward five compared to the alkali-free model basalt compositions in this study, thus changing the volume and compressibility of the FeO liquid component. The results from this study may be most appropriately applied to lunar basalts, which are impoverished in alkalis.

  18. 40 CFR Table 1 to Subpart Ja of... - Molar Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 7 2013-07-01 2013-07-01 false Molar Exhaust Volumes and Molar Heat... Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents Constituent MEVa dscf/mol MHCb Btu/mol... standard conditions of 68 °F and 1 atmosphere. b MHC = molar heat content (higher heating value basis),...

  19. 40 CFR Table 1 to Subpart Ja of... - Molar Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 7 2014-07-01 2014-07-01 false Molar Exhaust Volumes and Molar Heat... Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents Constituent MEVa dscf/mol MHCb Btu/mol... standard conditions of 68 °F and 1 atmosphere. b MHC = molar heat content (higher heating value basis),...

  20. Infinitely Dilute Partial Molar Properties of Proteins from Computer Simulation

    PubMed Central

    2015-01-01

    A detailed understanding of temperature and pressure effects on an infinitely dilute proteins conformational equilibrium requires knowledge of the corresponding infinitely dilute partial molar properties. Established molecular dynamics methodologies generally have not provided a way to calculate these properties without either a loss of thermodynamic rigor, the introduction of nonunique parameters, or a loss of information about which solute conformations specifically contributed to the output values. Here we implement a simple method that is thermodynamically rigorous and possesses none of the above disadvantages, and we report on the methods feasibility and computational demands. We calculate infinitely dilute partial molar properties for two proteins and attempt to distinguish the thermodynamic differences between a native and a denatured conformation of a designed miniprotein. We conclude that simple ensemble average properties can be calculated with very reasonable amounts of computational power. In contrast, properties corresponding to fluctuating quantities are computationally demanding to calculate precisely, although they can be obtained more easily by following the temperature and/or pressure dependence of the corresponding ensemble averages. PMID:25325571

  1. Isotope effects in aqueous systems. 9. Partial molar volumes of NaCl/H/sub 2/o and NaCl/D/sub 2/O solutions at 15, 30 and 45 /sup 0/C

    SciTech Connect

    Dessauges, G.; Miljevic, N.; Van Hook, W.A.

    1980-10-02

    Densities of NaCl solutions in H/sub 2/O and D/sub 2/O have been measured with high precision at 15, 30, and 45/sup 0/C by using a Mettler/Paar densitometer. The data in H/sub 2/O are compared with the best results of earlier workers. Solvent isotope effects on apparent molar volumes of NaCl solutions are large and, within experimental error, are proportional to m/sup 1/2/. They are interpreted in the context of available extend Debye-Huckel theories and discussed in terms of the molecular structure of the solvents.

  2. Molar volume and adsorption isotherm dependence of capillary forces in nanoasperity contacts.

    PubMed

    Asay, David B; Kim, Seong H

    2007-11-20

    The magnitude of the capillary force at any given temperature and adsorbate partial pressure depends primarily on four factors: the surface tension of the adsorbate, its liquid molar volume, its isothermal behavior, and the contact geometry. At large contacting radii, the adsorbate surface tension and the contact geometry are dominating. This is the case of surface force apparatus measurements and atomic force microscopy (AFM) experiments with micrometer-size spheres. However, as the size of contacting asperities decreases to the nanoscale as in AFM experiments with sharp tips, the molar volume and isotherm of the adsorbate become very important to capillary formation as well as capillary adhesion. This effect is experimentally and theoretically explored with simple alcohol molecules (ethanol, 1-butanol, and 1-pentanol) which have comparable surface tensions but differing liquid molar volumes. Adsorption isotherms for these alcohols on silicon oxide are also reported. PMID:17949117

  3. Prenatal screening tests may be a warning for the partial molar pregnancy? case report.

    PubMed

    Sargin, Mehmet Akif; Tug, Niyazi; Yassa, Murat; Yavuz, Arzu

    2015-01-01

    Prenatal screening tests are frequently requested for chromosomal abnormalities. Placental pathologies in early pregnancy may be overlooked, especially in partial molar pregnancy. We are reporting an incorrect preliminary diagnosed case with an increased risk of Down syndrome in her first-trimester screening test due to partial molar pregnancy. PMID:26175814

  4. The Voronoi volume and molecular representation of molar volume: equilibrium simple fluids.

    PubMed

    Hunjan, Jagtar Singh; Eu, Byung Chan

    2010-04-01

    The Voronoi volume of simple fluids was previously made use of in connection with volume transport phenomena in nonequilibrium simple fluids. To investigate volume transport phenomena, it is important to develop a method to compute the Voronoi volume of fluids in nonequilibrium. In this work, as a first step to this goal, we investigate the equilibrium limit of the nonequilibrium Voronoi volume together with its attendant related molar (molal) and specific volumes. It is proved that the equilibrium Voronoi volume is equivalent to the molar (molal) volume. The latter, in turn, is proved equivalent to the specific volume. This chain of equivalences provides an alternative procedure of computing the equilibrium Voronoi volume from the molar volume/specific volume. We also show approximate methods of computing the Voronoi and molar volumes from the information on the pair correlation function. These methods may be employed for their quick estimation, but also provide some aspects of the fluid structure and its relation to the Voronoi volume. The Voronoi volume obtained from computer simulations is fitted to a function of temperature and pressure in the region above the triple point but below the critical point. Since the fitting function is given in terms of reduced variables for the Lennard-Jones (LJ) model and the kindred volumes (i.e., specific and molar volumes) are in essence equivalent to the equation of state, the formula obtained is a reduced equation state for simple fluids obeying the LJ model potential in the range of temperature and pressure examined and hence can be used for other simple fluids. PMID:20387944

  5. The Component Slope Linear Model for Calculating Intensive Partial Molar Properties: Application to Waste Glasses

    SciTech Connect

    Reynolds, Jacob G.

    2013-01-11

    Partial molar properties are the changes occurring when the fraction of one component is varied while the fractions of all other component mole fractions change proportionally. They have many practical and theoretical applications in chemical thermodynamics. Partial molar properties of chemical mixtures are difficult to measure because the component mole fractions must sum to one, so a change in fraction of one component must be offset with a change in one or more other components. Given that more than one component fraction is changing at a time, it is difficult to assign a change in measured response to a change in a single component. In this study, the Component Slope Linear Model (CSLM), a model previously published in the statistics literature, is shown to have coefficients that correspond to the intensive partial molar properties. If a measured property is plotted against the mole fraction of a component while keeping the proportions of all other components constant, the slope at any given point on a graph of this curve is the partial molar property for that constituent. Actually plotting this graph has been used to determine partial molar properties for many years. The CSLM directly includes this slope in a model that predicts properties as a function of the component mole fractions. This model is demonstrated by applying it to the constant pressure heat capacity data from the NaOH-NaAl(OH{sub 4}H{sub 2}O system, a system that simplifies Hanford nuclear waste. The partial molar properties of H{sub 2}O, NaOH, and NaAl(OH){sub 4} are determined. The equivalence of the CSLM and the graphical method is verified by comparing results detennined by the two methods. The CSLM model has been previously used to predict the liquidus temperature of spinel crystals precipitated from Hanford waste glass. Those model coefficients are re-interpreted here as the partial molar spinel liquidus temperature of the glass components.

  6. Calculation of Derivative Thermodynamic Hydration and Aqueous Partial Molar Properties of Ions Based on Atomistic Simulations.

    PubMed

    Dahlgren, Bjrn; Reif, Maria M; Hnenberger, Philippe H; Hansen, Niels

    2012-10-01

    The raw ionic solvation free energies calculated on the basis of atomistic (explicit-solvent) simulations are extremely sensitive to the boundary conditions and treatment of electrostatic interactions used during these simulations. However, as shown recently [Kastenholz, M. A.; Hnenberger, P. H. J. Chem. Phys.2006, 124, 224501 and Reif, M. M.; Hnenberger, P. H. J. Chem. Phys.2011, 134, 144104], the application of an appropriate correction scheme allows for a conversion of the methodology-dependent raw data into methodology-independent results. In this work, methodology-independent derivative thermodynamic hydration and aqueous partial molar properties are calculated for the Na(+) and Cl(-) ions at P = 1 bar and T(-) = 298.15 K, based on the SPC water model and on ion-solvent Lennard-Jones interaction coefficients previously reoptimized against experimental hydration free energies. The hydration parameters considered are the hydration free energy and enthalpy. The aqueous partial molar parameters considered are the partial molar entropy, volume, heat capacity, volume-compressibility, and volume-expansivity. Two alternative calculation methods are employed to access these properties. Method I relies on the difference in average volume and energy between two aqueous systems involving the same number of water molecules, either in the absence or in the presence of the ion, along with variations of these differences corresponding to finite pressure or/and temperature changes. Method II relies on the calculation of the hydration free energy of the ion, along with variations of this free energy corresponding to finite pressure or/and temperature changes. Both methods are used considering two distinct variants in the application of the correction scheme. In variant A, the raw values from the simulations are corrected after the application of finite difference in pressure or/and temperature, based on correction terms specifically designed for derivative parameters at P and T(-). In variant B, these raw values are corrected prior to differentiation, based on corresponding correction terms appropriate for the different simulation pressures P and temperatures T. The results corresponding to the different calculation schemes show that, except for the hydration free energy itself, accurate methodological independence and quantitative agreement with even the most reliable experimental parameters (ion-pair properties) are not yet reached. Nevertheless, approximate internal consistency and qualitative agreement with experimental results can be achieved, but only when an appropriate correction scheme is applied, along with a careful consideration of standard-state issues. In this sense, the main merit of the present study is to set a clear framework for these types of calculations and to point toward directions for future improvements, with the ultimate goal of reaching a consistent and quantitative description of single-ion hydration thermodynamics in molecular dynamics simulations. PMID:26593002

  7. Melt densities for leucogranites and granitic pegmatites: Partial molar volumes for SiO 2, Al 2O 3, Na 2O, K 2O, Li 2O, Rb 2O, Cs 2O, MgO, CaO, SrO, BaO, B 2O 3, P 2O 5, F 2O -1, TiO 2, Nb 2O 5, Ta 2O 5, and WO 3

    NASA Astrophysics Data System (ADS)

    Knoche, R.; Dingwell, D. B.; Webb, S. L.

    1995-11-01

    The densities and thermal expansivities of thirty-eight haplogranitic silicate melts have been experimentally determined. The compositions represent the additions of approximately 5, 10, and 20 wt% of selected oxide components Al 2O 3, Na 2O, K 2O, Li 2O, Rb 2O, Cs 2O, MgO, CaO, SrO, BaO, TiO 2, Nb 2O 5, Ta 2O 5, and WO 3 to a base melt of haplogranitic (HPG8) composition. The densities of melts have been obtained by a combination of scanning dilatometry and room temperature Archimedean density determinations together with scanning calorimetry. The thermal expansivities were obtained by a combination of scanning calorimetry and scanning dilatometry. The results of the density and expansivity determinations for the melts are fit to a multicomponent linear least squares regression of molar volume vs. molar composition. The resulting partial molar volumes of the molten oxides are reported for a reference temperature of 750C. The multicomponent linear least squares regression yields a description of the database with a root mean squared deviation of 0.3%. The fit to these new partial molar volume data includes our previous data for B 2O 3, P 2O 5, and F 2O -1-bearing haplogranitic melts. The partial molar volumes of the oxides vary from 10.53 0.29 cm 3 mole -1 for MgO to 69.09 1.82 cm 3 mol -1 for P 2O 5. Compared on the basis of one oxygen per mole they range from 10.53 0.29 cm 3 mol -1 (MgO) to 55.38 1.69 cm 3 mol -1 (Cs 2O). The present data, taken together with an estimate of the partial molar volume of water in these melts (13.1 1.3 cm 3 mol -1) are recommended to be used to calculate the low pressure densities of leucogranitic and pegmatitic melts.

  8. A Structural Molar Volume Model for Oxide Melts Part III: Fe Oxide-Containing Melts

    NASA Astrophysics Data System (ADS)

    Thibodeau, Eric; Gheribi, Aimen E.; Jung, In-Ho

    2016-04-01

    As part III of this series, the model is extended to iron oxide-containing melts. All available experimental data in the FeO-Fe2O3-Na2O-K2O-MgO-CaO-MnO-Al2O3-SiO2 system were critically evaluated based on the experimental condition. The variations of FeO and Fe2O3 in the melts were taken into account by using FactSage to calculate the Fe2+/Fe3+ distribution. The molar volume model with unary and binary model parameters can be used to predict the molar volume of the molten oxide of the Li2O-Na2O-K2O-MgO-CaO-MnO-PbO-FeO-Fe2O3-Al2O3-SiO2 system in the entire range of compositions, temperatures, and oxygen partial pressures from Fe saturation to 1 atm pressure.

  9. A Structural Molar Volume Model for Oxide Melts Part III: Fe Oxide-Containing Melts

    NASA Astrophysics Data System (ADS)

    Thibodeau, Eric; Gheribi, Aimen E.; Jung, In-Ho

    2015-12-01

    As part III of this series, the model is extended to iron oxide-containing melts. All available experimental data in the FeO-Fe2O3-Na2O-K2O-MgO-CaO-MnO-Al2O3-SiO2 system were critically evaluated based on the experimental condition. The variations of FeO and Fe2O3 in the melts were taken into account by using FactSage to calculate the Fe2+/Fe3+ distribution. The molar volume model with unary and binary model parameters can be used to predict the molar volume of the molten oxide of the Li2O-Na2O-K2O-MgO-CaO-MnO-PbO-FeO-Fe2O3-Al2O3-SiO2 system in the entire range of compositions, temperatures, and oxygen partial pressures from Fe saturation to 1 atm pressure.

  10. Changes in apparent molar water volume and DKP solubility yield insights on the Hofmeister effect.

    PubMed

    Payumo, Alexander Y; Huijon, R Michael; Mansfield, Deauna D; Belk, Laurel M; Bui, Annie K; Knight, Anne E; Eggers, Daryl K

    2011-12-15

    This study examines the properties of a 4 2 matrix of aqueous cations and anions at concentrations up to 8.0 M. The apparent molar water volume, as calculated by subtracting the mass and volume of the ions from the corresponding solution density, was found to exceed the molar volume of ice in many concentrated electrolyte solutions, underscoring the nonideal behavior of these systems. The solvent properties of water were also analyzed by measuring the solubility of diketopiperazine (DKP) in 2.000 M salt solutions prepared from the same ion combinations. Solution rankings for DKP solubility were found to parallel the Hofmeister series for both cations and anions, whereas molar water volume concurred with the cation series only. The results are discussed within the framework of a desolvation energy model that attributes solute-specific changes in equilibria to solute-dependent changes in the free energy of bulk water. PMID:22029390

  11. Changes in Apparent Molar Water Volume and DKP Solubility Yield Insights on the Hofmeister Effect

    PubMed Central

    Payumo, Alexander Y.; Huijon, R. Michael; Mansfield, Deauna D.; Belk, Laurel M.; Bui, Annie K.; Knight, Anne E.; Eggers, Daryl K.

    2011-01-01

    This study examines the properties of a 4 2 matrix of aqueous cations and anions at concentrations up to 8.0 M. The apparent molar water volume, as calculated by subtracting the mass and volume of the ions from the corresponding solution density, was found to exceed the molar volume of ice in many concentrated electrolyte solutions, underscoring the non-ideal behavior of these systems. The solvent properties of water were also analyzed by measuring the solubility of diketopiperazine (DKP) in 2.000 M salt solutions prepared from the same ion combinations. Solution rankings for DKP solubility were found to parallel the Hofmeister series for both cations and anions, whereas molar water volume concurred with the cation series only. The results are discussed within the framework of a desolvation energy model that attributes solute-specific changes in equilibria to solute-dependent changes in the free energy of bulk water. PMID:22029390

  12. Partial Volume Correction in Quantitative Amyloid Imaging

    PubMed Central

    Su, Yi; Blazey, Tyler M.; Snyder, Abraham Z.; Raichle, Marcus E.; Marcus, Daniel S.; Ances, Beau M.; Bateman, Randall J.; Cairns, Nigel J.; Aldea, Patricia; Cash, Lisa; Christensen, Jon J.; Friedrichsen, Karl; Hornbeck, Russ C.; Farrar, Angela M.; Owen, Christopher J.; Mayeux, Richard; Brickman, Adam M.; Klunk, William; Price, Julie C.; Thompson, Paul M.; Ghetti, Bernardino; Saykin, Andrew J.; Sperling, Reisa A.; Johnson, Keith A.; Schofield, Peter R.; Buckles, Virginia; Morris, John C.; Benzinger, Tammie. LS.

    2014-01-01

    Amyloid imaging is a valuable tool for research and diagnosis in dementing disorders. As positron emission tomography (PET) scanners have limited spatial resolution, measured signals are distorted by partial volume effects. Various techniques have been proposed for correcting partial volume effects, but there is no consensus as to whether these techniques are necessary in amyloid imaging, and, if so, how they should be implemented. We evaluated a two-component partial volume correction technique and a regional spread function technique using both simulated and human Pittsburgh compound B (PiB) PET imaging data. Both correction techniques compensated for partial volume effects and yielded improved detection of subtle changes in PiB retention. However, the regional spread function technique was more accurate in application to simulated data. Because PiB retention estimates depend on the correction technique, standardization is necessary to compare results across groups. Partial volume correction has sometimes been avoided because it increases the sensitivity to inaccuracy in image registration and segmentation. However, our results indicate that appropriate PVC may enhance our ability to detect changes in amyloid deposition. PMID:25485714

  13. Partial volume correction in quantitative amyloid imaging.

    PubMed

    Su, Yi; Blazey, Tyler M; Snyder, Abraham Z; Raichle, Marcus E; Marcus, Daniel S; Ances, Beau M; Bateman, Randall J; Cairns, Nigel J; Aldea, Patricia; Cash, Lisa; Christensen, Jon J; Friedrichsen, Karl; Hornbeck, Russ C; Farrar, Angela M; Owen, Christopher J; Mayeux, Richard; Brickman, Adam M; Klunk, William; Price, Julie C; Thompson, Paul M; Ghetti, Bernadino; Saykin, Andrew J; Sperling, Reisa A; Johnson, Keith A; Schofield, Peter R; Buckles, Virginia; Morris, John C; Benzinger, Tammie L S

    2015-02-15

    Amyloid imaging is a valuable tool for research and diagnosis in dementing disorders. As positron emission tomography (PET) scanners have limited spatial resolution, measured signals are distorted by partial volume effects. Various techniques have been proposed for correcting partial volume effects, but there is no consensus as to whether these techniques are necessary in amyloid imaging, and, if so, how they should be implemented. We evaluated a two-component partial volume correction technique and a regional spread function technique using both simulated and human Pittsburgh compound B (PiB) PET imaging data. Both correction techniques compensated for partial volume effects and yielded improved detection of subtle changes in PiB retention. However, the regional spread function technique was more accurate in application to simulated data. Because PiB retention estimates depend on the correction technique, standardization is necessary to compare results across groups. Partial volume correction has sometimes been avoided because it increases the sensitivity to inaccuracy in image registration and segmentation. However, our results indicate that appropriate PVC may enhance our ability to detect changes in amyloid deposition. PMID:25485714

  14. Sealing versus partial caries removal in primary molars: a randomized clinical trial

    PubMed Central

    2014-01-01

    Background The resin-based pit and fissure sealant is considered a successful tool in caries prevention, however there is a growing evidence of its use in controlling already established caries in posterior teeth. The aim of this clinical trial is to verify the efficacy of pit and fissure sealants in arresting dentinal caries lesions compared to partial excavation and restorative treatment in primary molar teeth. Methods Thirty six patients with occlusal cavitated primary molar reaching outer half of dentin were selected. The patients were randomly allocated into two groups: sealant application (experimental group n?=?17) and restoration with composite resin (control group n?=?19). Clinical and radiograph evaluation were performed after 6, 12 and 18months. The chi-square test was used to verify the distribution of characteristics variables of the sample among the groups. The survival rate of treatments was evaluated using KaplanMeier survival and log-rank test. Fishers Exact and logistic regression tests were calculated in each evaluation period (??=?5%). Results The control group showed significantly better clinical survival after 18months (p?=?0.0025). In both groups, no caries progression was registered on the radiographic evaluations. Conclusions Sealing had similar efficacy in the arrestment of caries progression of cavitated occlusal lesions compared to partial excavation of the lesions, even though the frequency of re-treatments was significantly higher in sealed lesions. Trial registration Registro Brasileiro de Ensaios Clnicos (ReBEC): RBR-9kkv53 PMID:24884684

  15. The component slope linear model for calculating intensive partial molar properties /application to waste glasses and aluminate solutions

    SciTech Connect

    Reynolds, Jacob G.

    2013-01-11

    Partial molar properties are the changes occurring when the fraction of one component is varied while the fractions of all other component mole fractions change proportionally. They have many practical and theoretical applications in chemical thermodynamics. Partial molar properties of chemical mixtures are difficult to measure because the component mole fractions must sum to one, so a change in fraction of one component must be offset with a change in one or more other components. Given that more than one component fraction is changing at a time, it is difficult to assign a change in measured response to a change in a single component. In this study, the Component Slope Linear Model (CSLM), a model previously published in the statistics literature, is shown to have coefficients that correspond to the intensive partial molar properties. If a measured property is plotted against the mole fraction of a component while keeping the proportions of all other components constant, the slope at any given point on a graph of this curve is the partial molar property for that constituent. Actually plotting this graph has been used to determine partial molar properties for many years. The CSLM directly includes this slope in a model that predicts properties as a function of the component mole fractions. This model is demonstrated by applying it to the constant pressure heat capacity data from the NaOH-NaAl(OH){sub 4}-H{sub 2}O system, a system that simplifies Hanford nuclear waste. The partial molar properties of H{sub 2}O, NaOH, and NaAl(OH){sub 4} are determined. The equivalence of the CSLM and the graphical method is verified by comparing results determined by the two methods. The CSLM model has been previously used to predict the liquidus temperature of spinel crystals precipitated from Hanford waste glass. Those model coefficients are re-interpreted here as the partial molar spinel liquidus temperature of the glass components.

  16. The Component Slope Linear Model for Calculating Intensive Partial Molar Properties: Application to Waste Glasses and Aluminate Solutions - 13099

    SciTech Connect

    Reynolds, Jacob G.

    2013-07-01

    Partial molar properties are the changes occurring when the fraction of one component is varied while the fractions of all other component mole fractions change proportionally. They have many practical and theoretical applications in chemical thermodynamics. Partial molar properties of chemical mixtures are difficult to measure because the component mole fractions must sum to one, so a change in fraction of one component must be offset with a change in one or more other components. Given that more than one component fraction is changing at a time, it is difficult to assign a change in measured response to a change in a single component. In this study, the Component Slope Linear Model (CSLM), a model previously published in the statistics literature, is shown to have coefficients that correspond to the intensive partial molar properties. If a measured property is plotted against the mole fraction of a component while keeping the proportions of all other components constant, the slope at any given point on a graph of this curve is the partial molar property for that constituent. Actually plotting this graph has been used to determine partial molar properties for many years. The CSLM directly includes this slope in a model that predicts properties as a function of the component mole fractions. This model is demonstrated by applying it to the constant pressure heat capacity data from the NaOHNaAl(OH){sub 4}-H{sub 2}O system, a system that simplifies Hanford nuclear waste. The partial molar properties of H{sub 2}O, NaOH, and NaAl(OH){sub 4} are determined. The equivalence of the CSLM and the graphical method is verified by comparing results determined by the two methods. The CSLM model has been previously used to predict the liquidus temperature of spinel crystals precipitated from Hanford waste glass. Those model coefficients are re-interpreted here as the partial molar spinel liquidus temperature of the glass components. (authors)

  17. Partial molar enthalpies and reaction enthalpies from equilibrium molecular dynamics simulation

    SciTech Connect

    Schnell, Sondre K.; Skorpa, Ragnhild; Bedeaux, Dick; Kjelstrup, Signe; Vlugt, Thijs J. H.; Simon, Jean-Marc

    2014-10-14

    We present a new molecular simulation technique for determining partial molar enthalpies in mixtures of gases and liquids from single simulations, without relying on particle insertions, deletions, or identity changes. The method can also be applied to systems with chemical reactions. We demonstrate our method for binary mixtures of Weeks-Chandler-Anderson particles by comparing with conventional simulation techniques, as well as for a simple model that mimics a chemical reaction. The method considers small subsystems inside a large reservoir (i.e., the simulation box), and uses the construction of Hill to compute properties in the thermodynamic limit from small-scale fluctuations. Results obtained with the new method are in excellent agreement with those from previous methods. Especially for modeling chemical reactions, our method can be a valuable tool for determining reaction enthalpies directly from a single MD simulation.

  18. Partial volume correction using cortical surfaces

    NASA Astrophysics Data System (ADS)

    Blaasvr, Kamille R.; Haubro, Camilla D.; Eskildsen, Simon F.; Borghammer, Per; Otzen, Daniel; Ostergaard, Lasse R.

    2010-03-01

    Partial volume effect (PVE) in positron emission tomography (PET) leads to inaccurate estimation of regional metabolic activities among neighbouring tissues with different tracer concentration. This may be one of the main limiting factors in the utilization of PET in clinical practice. Partial volume correction (PVC) methods have been widely studied to address this issue. MRI based PVC methods are well-established.1 Their performance depend on the quality of the co-registration of the MR and PET dataset, on the correctness of the estimated point-spread function (PSF) of the PET scanner and largely on the performance of the segmentation method that divide the brain into brain tissue compartments.1, 2 In the present study a method for PVC is suggested, that utilizes cortical surfaces, to obtain detailed anatomical information. The objectives are to improve the performance of PVC, facilitate a study of the relationship between metabolic activity in the cerebral cortex and cortical thicknesses, and to obtain an improved visualization of PET data. The gray matter metabolic activity after performing PVC was recovered by 99.7 - 99.8 % , in relation to the true activity when testing on simple simulated data with different PSFs and by 97.9 - 100 % when testing on simulated brain PET data at different cortical thicknesses. When studying the relationship between metabolic activities and anatomical structures it was shown on simulated brain PET data, that it is important to correct for PVE in order to get the true relationship.

  19. Partial volume simulation in software breast phantoms

    NASA Astrophysics Data System (ADS)

    Chen, Feiyu; Pokrajac, David; Shi, Xiquan; Liu, Fengshan; Maidment, Andrew D. A.; Bakic, Predrag R.

    2012-03-01

    A modification to our previous simulation of breast anatomy is proposed, in order to improve the quality of simulated projections generated using software breast phantoms. Anthropomorphic software breast phantoms have been used for quantitative validation of breast imaging systems. Previously, we developed a novel algorithm for breast anatomy simulation, which did not account for the partial volume (PV) of various tissues in a voxel; instead, each phantom voxel was assumed to contain single tissue type. As a result, phantom projection images displayed notable artifacts near the borders between regions of different materials, particularly at the skin-air boundary. These artifacts diminished the realism of phantom images. One solution is to simulate smaller voxels. Reducing voxel size, however, extends the phantom generation time and increases memory requirements. We achieved an improvement in image quality without reducing voxel size by the simulation of PV in voxels containing more than one simulated tissue type. The linear x-ray attenuation coefficient of each voxel is calculated by combining attenuation coefficients proportional to the voxel subvolumes occupied by the various tissues. A local planar approximation of the boundary surface is employed, and the skin volume in each voxel is computed by decomposition into simple geometric shapes. An efficient encoding scheme is proposed for the type and proportion of simulated tissues in each voxel. We illustrate the proposed methodology on phantom slices and simulated mammographic projections. Our results show that the PV simulation has improved image quality by reducing quantization artifacts.

  20. Molar Volume Modeling of Ti-Al-Nb and Ti-Al-Mo Ternary Systems

    NASA Astrophysics Data System (ADS)

    Zhu, Jun; Zhang, Chuan; Cao, Weisheng; Chen, Shuanglin; Zhang, Fan; Park, Joon Sik; Yi, Seonghoon

    2015-08-01

    Molar volume modeling was performed for both Ti-Al-Nb and Ti-Al-Mo ternary systems based on the thermodynamic modeling of these two systems. Comparison between the calculated phase equilibria and the experimental data proved the accuracy of thermodynamic modeling. With the calculated density contour curves superimposed on the equilibrium phase diagram, it provides a map for alloy developers to identify the promising alloy compositions that satisfy both the phase stability and density requirements and rule out those that fail to meet the requirements.

  1. Volume analysis of heat-induced cracks in human molars: A preliminary study

    PubMed Central

    Sandholzer, Michael A.; Baron, Katharina; Heimel, Patrick; Metscher, Brian D.

    2014-01-01

    Context: Only a few methods have been published dealing with the visualization of heat-induced cracks inside bones and teeth. Aims: As a novel approach this study used nondestructive X-ray microtomography (micro-CT) for volume analysis of heat-induced cracks to observe the reaction of human molars to various levels of thermal stress. Materials and Methods: Eighteen clinically extracted third molars were rehydrated and burned under controlled temperatures (400, 650, and 800°C) using an electric furnace adjusted with a 25°C increase/min. The subsequent high-resolution scans (voxel-size 17.7 μm) were made with a compact micro-CT scanner (SkyScan 1174). In total, 14 scans were automatically segmented with Definiens XD Developer 1.2 and three-dimensional (3D) models were computed with Visage Imaging Amira 5.2.2. The results of the automated segmentation were analyzed with an analysis of variance (ANOVA) and uncorrected post hoc least significant difference (LSD) tests using Statistical Package for Social Sciences (SPSS) 17. A probability level of P < 0.05 was used as an index of statistical significance. Results: A temperature-dependent increase of heat-induced cracks was observed between the three temperature groups (P < 0.05, ANOVA post hoc LSD). In addition, the distributions and shape of the heat-induced changes could be classified using the computed 3D models. Conclusion: The macroscopic heat-induced changes observed in this preliminary study correspond with previous observations of unrestored human teeth, yet the current observations also take into account the entire microscopic 3D expansions of heat-induced cracks within the dental hard tissues. Using the same experimental conditions proposed in the literature, this study confirms previous results, adds new observations, and offers new perspectives in the investigation of forensic evidence. PMID:25125923

  2. Excess molar volumes of mixtures of hexane + natural oils from 298.15 to 313.15 K

    SciTech Connect

    Gonzalez, C.; Resa, J.M.; Ruiz, A.; Gutierrez, J.I.

    1997-03-01

    Excess molar volume data for mixtures containing hexane with three edible oils: olive, corn, and pip of grape have been determined from density measurements at various temperatures between 298.15 and 313.15 K using a vibrating tube densimeter. Results have been correlated by the Redlich-Kister equation. Systems showed negative deviations from ideality in the whole composition range.

  3. Thermodynamics of aqueous aluminum: standard partial molar heat capacities of Al/sup 3 +/ from 10 to 55/sup 0/C

    SciTech Connect

    Hovey, J.K.; Tremaine, P.R.

    1986-03-01

    The thermodynamic properties of aqueous aluminum species are required over wide ranges of temperature in order to model mineral dissolution and transport in steam injection and combustion processes for the in situ recovery of bitumen. The same data are needed to model aqueous solutions associated with the formation of hydrothermal ore deposits, geothermal power generation, the marine chemistry of deep hydrothermal vents, hydrometallurgy, and the corrosion behavior of aluminum alloys. Apparent molar heat capacities and volumes of Al(NO/sub 3/)/sub 3/ and AlCl/sub 3/ have been measured at 25/sup 0/C in dilute aqueous acid solutions to suppress hydrolysis. Heat capacity results for AlCl/sub 3/ span the range 10-55/sup 0/C. The measurements yield standard partial molar heat capacities, anti C/sub p//sup 0/, and volumes, anti V/sup 0/, for the Al/sup 3 +/ (aq) ion: anti V/sub 298//sup 0/ (Al/sup 3 +/, aq) = -45.3 cm/sup 3/ mol/sup -1/, anti C/sub pT//sup 0/(Al/sup 3 +/, aq) = 566.2 - 1.452% - 27338/(T - 190), where T is the absolute temperature (K). Their result for anti V/sub 298//sup 0/ is consistent with published semi-empirical correlations. The result for anti C/sub p298//sup 0/ is more negative than that predicted from the entropy correspondence principle by 135 J K/sup -1/ mol/sup -1/ and casts doubt upon the correspondence method as a predictive tool. The heat capacities approach born behavior at elevated temperatures and appear to be consistent with the Helgeson-Kirkham-Flowers model for extrapolations to higher temperatures.

  4. Hygrometer for Detecting Water in Partially Enclosed Volumes

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert C.; Surma, Jan; Parks, Steve

    2005-01-01

    A portable hygrometer has been devised to implement a pre-existing technique for detecting water trapped in partially enclosed volumes that may be difficult to reach and cannot be examined directly. The technique is based on the fact that eventually the air in such a volume becomes saturated or nearly so. The technique is straightforward: One measures the relative humidity and temperature of both the ambient air and a sample of air from the enclosed volume. If the relative humidity of the sample is significantly greater than that of the ambient air and/or if the sample is at or close to the dew point, then it can be concluded that water is trapped in the volume. Of course, the success of this technique depends on the existence of an access hole through which one can withdraw some air from the enclosed volume.

  5. Simple program calculates partial liquid volumes in vessels

    SciTech Connect

    Koch, P.

    1992-04-13

    This paper reports on a simple calculator program which solves problems of partial liquid volumes for a variety of storage and process vessels, including inclined cylindrical vessels and those with conical heads. Engineers in the oil refining and chemical industries are often confronted with the problem of estimating partial liquid volumes in storage tanks or process vessels. Cistern, the calculator program presented here, allows fast and accurate resolution of problems for a wide range of vessels without user intervention, other than inputting the problem data. Running the program requires no mathematical skills. Cistern is written for Hewlett-Packard HP 41CV or HP 41CX programmable calculators (or HP 41C with extended memory modules).

  6. Anisotropic Partial Volume CSF Modeling for EEG Source Localization

    PubMed Central

    Hyde, Damon E.; Duffy, Frank H.; Warfield, Simon K.

    2012-01-01

    Electromagnetic source localization (ESL) provides non-invasive evaluation of brain electrical activity for neurology research and clinical evaluation of neurological disorders such as epilepsy. Accurate ESL results are dependent upon the use of patient-specific models of bioelectric conductivity. While the effects of anisotropic conductivities in the skull and white matter have been previously studied, little attention has been paid to the accurate modeling of the highly conductive cerebrospinal fluid (CSF) region. This study examines the effect that partial volume errors in CSF segmentations have upon the ESL bioelectric model. These errors arise when segmenting sulcal channels whose widths are similar to the resolution of the magnetic resonance (MR) images used for segmentation, as some voxels containing both CSF and grey matter cannot be definitively assigned a single label. These problems, particularly prevalent in pediatric populations, make voxelwise segmentation of CSF compartments a difficult problem. Given the high conductivity of CSF, errors in modeling this region my result in large errors in the bioelectric model. We introduce here a new approach for using estimates of partial volume fractions in the construction of patient specific bioelectric models. In regions where partial volume errors are expected, we use a layered gray matter-CSF model to construct equivalent anisotropic conductivity tensors. This allows us to account for the inhomogeneity of the tissue within each voxel. Using this approach, we are able to reduce the error in the resulting bioelectric models, as evaluated against a known high resolution model. Additionally, this model permits us to evaluate the effects of sulci modeling errors and quantify the mean error as a function of the change in sulci width. Our results suggest that both under and over-estimation of the CSF region leads to significant errors in the bioelectric model. While a model with fixed partial volume fraction is able to reduce this error, we see the largest improvement when using voxel specific partial volume estimates. Our cross-model analyses suggest that an approximately linear relationship exists between sulci error and the error in the resulting bioelectric model. Given the difficulty of accurately segmenting narrow sulcal channels, this suggests that our approach may be capable of improving the accuracy of patient specific bioelectric models by several percent, while introducing only minimal additional computational requirements. PMID:22652021

  7. Densities and excess molar volumes of binary mixtures containing propylene carbonate + chlorohydrocarbons at 298.15 K and atmospheric pressure

    SciTech Connect

    Comelli, F.; Francesconi, R.

    1995-11-01

    Densities and excess molar volumes, V{sub m}{sup E}, for binary mixtures containing propylene carbonate + 10 chlorohydrocarbons (dichloromethane, 1,2-dichloroethane, 1,3-dichloropropane, 1,4-dichlorobuthane, 1,6-dichlorohexane, 1,10-dichlorodecane, 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, trans-1,2-dichloroethene, and trichloroethene) have been measured at 298.15 K and at atmospheric pressure using an Anton Paar digital vibrating tube density meter. The results are fitted to the Redlich-Kister equation. The values of V{sub m}{sup E} for the mixtures containing dichloroalkanes show an increasing trend with the increase of the chain length and vary from a minimum of {minus}0.24 cm{sup 3}/mol for dichloromethane up to a maximum of +0.31 cm{sup 3}/mol for 1,10-dichlorodecane. The excess molar volumes for the other mixtures are negative over the entire range of composition. Results are qualitatively discussed in terms of molecular interactions.

  8. Investigation of molar volume and surfactant characteristics of water-soluble organic compounds in biomass burning aerosol

    NASA Astrophysics Data System (ADS)

    Asa-Awuku, A.; Sullivan, A. P.; Hennigan, C. J.; Weber, R. J.; Nenes, A.

    2008-02-01

    In this study, we characterize the CCN activity of the water-soluble organics in biomass burning aerosol. The aerosol after collection upon filters is dissolved in water using sonication. Hydrophobic and hydrophilic components are fractionated from a portion of the original sample using solid phase extraction, and subsequently desalted. The surface tension and CCN activity of these different samples are measured with a KSV CAM 200 goniometer and a DMT Streamwise Thermal Gradient CCN Counter, respectively. The measurements show that the strongest surfactants are isolated in the hydrophobic fraction, while the hydrophilics exhibit negligible surface tension depression. The presence of salts (primarily (NH4)2SO4) in the hydrophobic fraction substantially enhances surface tension depression; their synergistic effects considerably enhance CCN activity, exceeding that of pure (NH4)2SO4. From our analysis, average thermodynamic properties (i.e, molar volume) are determined for samples using our newly developed Khler Theory Analysis (KTA) method. The molar mass of the hydrophilic and hydrophobic aerosol components is estimated to be 8726 g mol-1 and 780231 g mol-1, respectively. KTA also suggests that the relative proportion (in moles) of hydrophobic to hydrophilic compounds in the original sample to be 1:3. For the first time, KTA is applied to an aerosol with this level of complexity and displays its potential for providing physically-based constraints for GCM parameterizations of the aerosol indirect effect.

  9. Phenomenological Partial Specific Volumes for G-Quadruplex DNAs

    PubMed Central

    Hellman, Lance M.; Rodgers, David W.; Fried, Michael G.

    2009-01-01

    Accurate partial specific volume (??) values are required for sedimentation velocity and sedimentation equilibrium analyses. For nucleic acids, the estimation of these values is complicated by the fact that ?? depends on base composition, secondary structure, solvation and the concentrations and identities of ions in the surrounding buffer. Here we describe sedimentation equilibrium measurements of the apparent isopotential partial specific volume ?? for two G-quadruplex DNAs and a single-stranded DNA of similar molecular weight and base composition. The G-quadruplex DNAs are a 22 nucleotide fragment of the human telomere consensus sequence and a 27 nucleotide fragment from the human c-myc promoter. The single-stranded DNA is 26 nucleotides long and is designed to have low propensity to form secondary structures. Parallel measurements were made in buffers containing NaCl and in buffers containing KCl, spanning the range 0.09M ? [salt] ? 2.3M. Limiting values of ??, extrapolated to [salt] = 0M, were: 22-mer (NaCl-form), 0.525 0.004 mL/g; 22-mer (KCl-form), 0.531 0.006 mL/g; 27-mer (NaCl-form), 0.548 0.005 mL/g; 27-mer (KCl-form), 0.557 0.006 mL/g; 26-mer (NaCl-form), 0.555 0.004 mL/g; 26-mer (KCl-form), 0.564 0.006 mL/g. Small changes in ?? with [salt] suggest that large changes in counterion association or hydration are unlikely to take place over these concentration ranges. PMID:19238377

  10. Improved prediction of octanol-water partition coefficients from liquid-solute water solubilities and molar volumes

    USGS Publications Warehouse

    Chiou, C.T.; Schmedding, D.W.; Manes, M.

    2005-01-01

    A volume-fraction-based solvent-water partition model for dilute solutes, in which the partition coefficient shows a dependence on solute molar volume (V??), is adapted to predict the octanol-water partition coefficient (K ow) from the liquid or supercooled-liquid solute water solubility (Sw), or vice versa. The established correlation is tested for a wide range of industrial compounds and pesticides (e.g., halogenated aliphatic hydrocarbons, alkylbenzenes, halogenated benzenes, ethers, esters, PAHs, PCBs, organochlorines, organophosphates, carbamates, and amidesureas-triazines), which comprise a total of 215 test compounds spanning about 10 orders of magnitude in Sw and 8.5 orders of magnitude in Kow. Except for phenols and alcohols, which require special considerations of the Kow data, the correlation predicts the Kow within 0.1 log units for most compounds, much independent of the compound type or the magnitude in K ow. With reliable Sw and V data for compounds of interest, the correlation provides an effective means for either predicting the unavailable log Kow values or verifying the reliability of the reported log Kow data. ?? 2005 American Chemical Society.

  11. A molecular dynamics study of ambient and high pressure phases of silica: Structure and enthalpy variation with molar volume

    NASA Astrophysics Data System (ADS)

    Rajappa, Chitra; Sringeri, S. Bhuvaneshwari; Subramanian, Yashonath; Gopalakrishnan, J.

    2014-06-01

    Extensive molecular dynamics studies of 13 different silica polymorphs are reported in the isothermal-isobaric ensemble with the Parrinello-Rahman variable shape simulation cell. The van Beest-Kramer-van Santen (BKS) potential is shown to predict lattice parameters for most phases within 2%-3% accuracy, as well as the relative stabilities of different polymorphs in agreement with experiment. Enthalpies of high-density polymorphs - CaCl2-type, ?-PbO2-type, and pyrite-type - for which no experimental data are available as yet, are predicted here. Further, the calculated enthalpies exhibit two distinct regimes as a function of molar volumefor low and medium-density polymorphs, it is almost independent of volume, while for high-pressure phases a steep dependence is seen. A detailed analysis indicates that the increased short-range contributions to enthalpy in the high-density phases arise not only from an increased coordination number of silicon but also shorter Si-O bond lengths. Our results indicate that amorphous phases of silica exhibit better optimization of short-range interactions than crystalline phases at the same density while the magnitude of Coulombic contributions is lower in the amorphous phase.

  12. Vapor-liquid equilibria and salt apparent molar volumes of the water + 2-propanol + tetrabutylammonium bromide system

    SciTech Connect

    Slusher, J.T.; Decker, K.J.; Liu, H.; Cummings, P.T. . Dept. of Chemical Engineering); Vega, C.A. . Dept. of Chemistry); O'Connell, J.P. . Chemical Engineering)

    1994-07-01

    Vapor-liquid equilibrium and density measurements have been performed on 1.00--5.89 m tetrabutylammonium bromide (TBAB) in mixtures of 2-propanol and water. The VLE experiments were performed using a modified Othmer still at ambient pressure. The effect of salt on the relative volatility of 2-propanol was evaluated at molalities of 1.00, 1.79, and 5.89 over the full range of solvent composition. At each salt molality, as the alcohol concentration increased, salting-in and then salting-out behavior of the alcohol was observed. The azeotrope was shifted but apparently not eliminated for the salt concentrations studied. Density measurements at 25, 40, and 55 C were taken using a vibrating tube densimeter at four salt molalities over the full range of solvent composition. As salt molality increased, the apparent molar volume of TBAB exhibits a minimum between 1 to 2 m TBAB in pure water, it is slightly larger and monotonically increased in pure 2-propanol, and it is larger yet, with a maximum at lower 2-propanol amounts, in the ternary mixture.

  13. Partial volume estimation: an improvement for eigenimage method

    NASA Astrophysics Data System (ADS)

    Siadat, Mohammad-Reza; Soltanian-Zadeh, Hamid

    2000-06-01

    This paper presents a sub-voxel analysis method for multi- parameter volumetric images such as MRI to provide partial volume estimation. The proposed method finds a continuous function for a neighboring structure of each voxel. The estimation function and neighboring structure are chosen from the quadratic/cubic polynomials and a set of 2D/3D symmetric neighborhood architectures, respectively. Then, a new form of the eigenimage method, based on Gram-Schmidt orthogonalization, is derived for each choice of estimation function and neighboring structure. Finally, the above estimators are applied to a simulation model consisting of materials similar to CSF, WM, and GM of the human brain in T1- , T2-, and PD-weighted MRI. In the presence of noise, the examined continuous estimators show a smaller standard deviation (up to 40%) than the standard eigenimage method. Also the chosen estimators have analytical solution for their Gram-Schmidt filters, so their execution times are comparable with that of the standard eigenimage method. In addition, the proposed approach can determine the 3D distribution of each material and extract the connecting surfaces of the materials within each voxel.

  14. The molar volume of FeO-MgO-Fe2O3-Cr2O3-Al2O3-TiO2 spinels

    NASA Astrophysics Data System (ADS)

    Hamecher, Emily A.; Antoshechkina, Paula M.; Ghiorso, Mark S.; Asimow, Paul D.

    2013-01-01

    We define and calibrate a new model of molar volume as a function of pressure, temperature, ordering state, and composition for spinels in the supersystem (Mg, Fe2+)(Al, Cr, Fe3+)2O4 - (Mg, Fe2+)2TiO4. We use 832 X-ray and neutron diffraction measurements performed on spinels at ambient and in situ high- P, T conditions to calibrate end-member equations of state and an excess volume model for this system. The effect on molar volume of cation ordering over the octahedral and tetrahedral sites is captured with linear dependence on Mg2+, Al3+, and Fe3+ site occupancy terms. We allow standard-state volumes and coefficients of thermal expansion of the end members to vary within their uncertainties during extraction of the mixing properties, in order to achieve the best fit. Published equations of state of the various spinel end members are analyzed to obtain optimal values of the bulk modulus and its pressure derivative, for each explicit end member. For any spinel composition in the supersystem, the model molar volume is obtained by adding excess volume and cation order-dependent terms to a linear combination of the five end-member volumes, estimated at pressure and temperature using the high- T Vinet equation of state. The preferred model has a total of 9 excess volume and order-dependent parameters and fits nearly all experiments to within 0.02 J/bar/mol, or better than 0.5 % in volume. The model is compared to the current MELTS spinel model with a demonstration of the impact of the model difference on the estimated spinel-garnet lherzolite transition pressure.

  15. The Molar Volume of FeO-MgO-Fe2O3-Cr2O3-Al2O3-TiO2 Spinels

    NASA Astrophysics Data System (ADS)

    Hamecher, E. A.; Antoshechkina, P. M.; Ghiorso, M. S.; Asimow, P. D.

    2011-12-01

    A new model of molar volume has been calibrated in the spinel supersystem (Mg,Fe2+)(Al,Cr,Fe3+)2O4 - (Mg,Fe2+)2TiO4. A total of 832 X-ray and neutron diffraction experiments performed on spinels at ambient and in situ high-P, T conditions (from the American Mineralogist Crystal Structure Database (Downs and Hall-Wallace, 2003) and other sources) were used to calibrate end-member equations of state and an excess volume model for this system. The effect on molar volume of cation ordering over the octahedral and tetrahedral sites is captured with linear dependence on Mg2+, Al3+, and Fe3+ site occupancy terms. We allowed standard state volumes and coefficients of thermal expansion of the end members to vary within their uncertainties during extraction of the mixing properties, in order to achieve the best fit. Published equations of states of the various spinel end members were analyzed to obtain optimal values of the bulk modulus and its pressure derivative, for each explicit end member. For any spinel composition in the supersystem, the model molar volume is obtained by adding excess volume and cation order-dependent terms to a linear combination of the five end member volumes, estimated at pressure and temperature using the high-T Vinet equation of state. The model has a total of 31 parameters and fits nearly all experiments to within 0.02 J/bar/mol, or better than 0.5% in volume. The model is compared to the current MELTS (Ghiorso and Sack, 1995; Ghiorso et al., 2002) spinel model with a demonstration of the impact of the model difference on the estimated spinel-garnet lherzolite transition pressure. Our primary motivation in this work is the development of a comprehensive spinel molar volume model for use in calibration of activity-composition models of garnet and pyroxene solid solutions. The thermodynamic models, along with a new silicate liquid equation of state, will be incorporated into the next generation MELTS model, xMELTS. The new solid solution models will include some minor components, including Ti4+ and Cr3+. Because most constraints on the activity of garnet and pyroxene at high-P are derived from experiments with coexisting spinel, we must be confident in the ability of our spinel model to realistically reproduce thermodynamic behavior over all applicable compositions. Additionally, producing a spinel molar volume model calibrated with recent in situ high-P, T diffraction data is crucial to our ability to accurately model the spinel-garnet transition in Earth's upper mantle. For example, we recently calibrated Cr-Al exchange equilibria for garnet and spinel. When this new calibration is used with the current MELTS model, a region of garnet-spinel coexistence in lherzolites is predicted with width in pressure comparable to experimental constraints. The transition occurs, however, at the unexpectedly low pressure of ~1.7 GPa. The improved model of spinel molar volume presented here, along with a new garnet molar volume model in the system FeO-MgO-CaO-Fe2O3-Cr2O3-Al2O3-TiO2-Na2O-SiO2 currently being calibrated, will enable coupled recalibration of the garnet and pyroxene models to match both the absolute pressure and width of this key transition in mantle lithology.

  16. A new anisotropic diffusion method, application to partial volume effect reduction

    NASA Astrophysics Data System (ADS)

    Salvado, Olivier; Wilson, David L.

    2006-03-01

    The partial volume effect is a significant limitation in medical imaging that results in blurring when the boundary between two structures of interest falls in the middle of a voxel. A new anisotropic diffusion method allows one to create interpolated 3D images corrected for partial volume, without enhancement of noise. After a zero-order interpolation, we apply a modified version of the anisotropic diffusion approach, wherein the diffusion coefficient becomes negative for high gradient values. As a result, the new scheme restores edges between regions that have been blurred by partial voluming, but it acts as normal anisotropic diffusion in flat regions, where it reduces noise. We add constraints to stabilize the method and model partial volume; i.e., the sum of neighboring voxels must equal the signal in the original low resolution voxel and the signal in a voxel is kept within its neighbor's limits. The method performed well on a variety of synthetic images and MRI scans. No noticeable artifact was induced by interpolation with partial volume correction, and noise was much reduced in homogeneous regions. We validated the method using the BrainWeb project database. Partial volume effect was simulated and restored brain volumes compared to the original ones. Errors due to partial volume effect were reduced by 28% and 35% for the 5% and 0% noise cases, respectively. The method was applied to in vivo "thick" MRI carotid artery images for atherosclerosis detection. There was a remarkable increase in the delineation of the lumen of the carotid artery.

  17. In silico characterization of protein partial molecular volumes and hydration shells.

    PubMed

    Del Galdo, Sara; Marracino, Paolo; D'Abramo, Marco; Amadei, Andrea

    2015-11-18

    In this paper we present a computational approach, based on NVT molecular dynamics trajectories, that allows the direct evaluation of the protein partial molecular volume. The results obtained for five different globular proteins demonstrate the accuracy of this computational procedure in reproducing protein partial molecular volumes, providing quantitative characterization of the hydration shell in terms of the protein excluded volume, hydration shell ellipsoidal volume and related solvent density. Remarkably, our data indicate for the hydration shell a ?10% solvent density increase with respect to the liquid water bulk density, in excellent agreement with the available experimental data. PMID:26549621

  18. Partial volume effect modeling for segmentation and tissue classification of brain magnetic resonance images: A review

    PubMed Central

    Tohka, Jussi

    2014-01-01

    Quantitative analysis of magnetic resonance (MR) brain images are facilitated by the development of automated segmentation algorithms. A single image voxel may contain of several types of tissues due to the finite spatial resolution of the imaging device. This phenomenon, termed partial volume effect (PVE), complicates the segmentation process, and, due to the complexity of human brain anatomy, the PVE is an important factor for accurate brain structure quantification. Partial volume estimation refers to a generalized segmentation task where the amount of each tissue type within each voxel is solved. This review aims to provide a systematic, tutorial-like overview and categorization of methods for partial volume estimation in brain MRI. The review concentrates on the statistically based approaches for partial volume estimation and also explains differences to other, similar image segmentation approaches. PMID:25431640

  19. Influence of base composition, base sequence, and duplex structure on DNA hydration: apparent molar volumes and apparent molar adiabatic compressibilities of synthetic and natural DNA duplexes at 25 degrees C.

    PubMed

    Chalikian, T V; Sarvazyan, A P; Plum, G E; Breslauer, K J

    1994-03-01

    Using high-precision densitometric and ultrasonic measurements, we have determined, at 25 degrees C, the apparent molar volumes, phi V, and the apparent molar compressibilities, phi KS, of five natural and three synthetic B-form DNA duplexes with varying base compositions and base sequences. We find that phi V ranges from 152.0 to 186.6 cm3 mol-1, while phi KS ranges from -73.0 x 10(-4) to -32.6 x 10(-4) cm3 mol-1 bar-1. We interpret these data in terms of DNA hydration which, by the definition employed in this work, refers to those water molecules whose density and compressibility differ from those of bulk water due to interactions with the DNA solute. This definition implies that hydration depends not just on the quantity but also on the quality of the solvent molecules perturbed by the solute. In fact, we find that the number of water molecules perturbed by the DNA duplexes (the quantity of water in their hydration shells) is approximately the same for all of the B-form double helixes studied, while the quality of this water differs as measured by its density and compressibility, thereby yielding differences in the overall hydration properties. Specifically, we find a linear relationship between the density and the coefficient of adiabatic compressibility, beta Sh, of water in the hydration shell of the DNA duplexes, with the range of values for beta Sh being only 65-80% of the value of bulk water.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8117699

  20. Densities, Excess Molar Volumes, Viscosities, and Refractive Indices of Binary Mixtures of n-Butyl Acetate with 1-Chloroalkanes (C4-C8) at 298.15 K

    NASA Astrophysics Data System (ADS)

    Iloukhani, H.; Khanlarzadeh, K.; Rakhshi, M.

    2011-03-01

    Densities, viscosities, and refractive indices of binary mixtures of n-butyl acetate (1) +1-chlorobutane (2), +1-chloropentane (2), +1-chlorohexane (2), +1-chloroheptane (2), and +1-chlorooctane (2) were measured at 298.15 K for the liquid region and at ambient pressure for the whole composition range. The excess molar volumes V E were calculated from experimental densities. McAllister's three-body interaction, and Hind and Grunberg-Nissan models are used for correlating the viscosity of binary mixtures. The experimental data of binaries are analyzed to discuss the nature and strength of intermolecular interactions in these mixtures.

  1. FMDP Reactor Alternative Summary Report: Volume 3 - partially complete LWR alternative

    SciTech Connect

    Greene, S.R.; Fisher, S.E.; Bevard, B.B.

    1996-09-01

    The Department of Energy Office of Fissile Materials Disposition (DOE/MD) initiated a detailed analysis activity to evaluate each of ten plutonium disposition alternatives that survived an initial screening process. This document, Volume 3 of a four volume report summarizes the results of these analyses for the partially complete LWR (PCLWR) reactor based plutonium disposition alternative.

  2. The effect of perfluorocarbon vapour on the measurement of respiratory tidal volume during partial liquid ventilation.

    PubMed

    Davies, M W; Dunster, K R

    2000-08-01

    During partial liquid ventilation perfluorocarbon vapour is present in the exhaled gases. The volumes of these gases are measured by pneumotachometers. Error in measuring tidal volumes will give erroneous measurement of lung compliance during partial liquid ventilation. We aim to compare measured tidal volumes with and without perfluorocarbon vapour using tidal volumes suitable for use in neonates. Tidal volumes were produced with a 100 ml calibration syringe from 20 to 100 ml and with a calibrated Harvard rodent ventilator from 2.5 to 20 ml. Control tidal volumes were drawn from a humidifier chamber containing water vapour and the PFC tidal volumes were drawn from a humidifier chamber containing water and perfluorocarbon (FC-77) vapour. Tidal volumes were measured by a fixed orifice, target, differential pressure flowmeter (VenTrak) or a hot-wire anenometer (Bear Cub) placed between the calibration syringe or ventilator and the humidifier chamber. All tidal volumes measured with perfluorocarbon vapour were increased compared with control (ANOVA p < 0.001 and post t-test p < 0.0001). Measured tidal volume increased from 7 to 16% with the fixed orifice type flow-meter, and from 35 to 41% with the hot-wire type. In conclusion, perfluorocarbon vapour flowing through pneumotachometers gives falsely high tidal volume measurements. Calculation of lung compliance must take into account the effect of perfluorocarbon vapour on the measurement of tidal volume. PMID:10984211

  3. Partial volume correction for volume estimation of liver metastases and lymph nodes in CT scans using spatial subdivision

    NASA Astrophysics Data System (ADS)

    Heckel, Frank; Dicken, Volker; Bostel, Tilman; Fabel, Michael; Kiessling, Andreas; Peitgen, Heinz-Otto

    2010-03-01

    In oncological therapy monitoring, the estimation of tumor growth from consecutive CT scans is an important aspect in deciding whether the given treatment is adequate for the patient. This can be done by measuring and comparing the volume of a lesion in the scans based on a segmentation. However, simply counting the voxels within the segmentation mask can lead to significant differences in the volume, if the lesion has been segmented slightly differently by various readers or in different scans, due to the limited spatial resolution of CT and due to partial volume effects. We present a novel algorithm for measuring the volume of liver metastases and lymph nodes which considers partial volume effects at the surface of a lesion. Our algorithm is based on a spatial subdivision of the segmentation. We have evaluated the algorithm on a phantom and a multi-reader study. Our evaluations have shown that our algorithm allows determining the volume more accurately even for larger slice thicknesses. Moreover, it reduces inter-observer variability of volume measurements significantly. The calculation of the volume takes 2 seconds for 503 voxels on a single 2.66GHz Intel Core2 CPU.

  4. Partial breast irradiation: targeting volume or breast molecular subtypes?

    PubMed

    Orecchia, Roberto; Leonardi, Maria Cristina

    2013-08-01

    The eligibility criteria for partial breast irradiation (APBI) are mainly based on histopathological factors, which not always explain the clinical behaviour of breast cancers. International guidelines represent useful platform to collect data for continued refinement of patient selection, but the clinical applicability to APBI series showed some limitations, particularly among the intermediate and high-risk groups. The heterogeneity of APBI techniques, along with the heterogeneity of breast cancer, generates clinical results, where the predictive value of the histopathological factors can assume different weight. There is a need of further refinement and implementation of risk factors. Currently, the impact of breast cancer subtype on local control is matter of investigation, and treatment decision about radiotherapy is generally made without regard to the breast cancer subtype. However, receptor status information is easily available and some histopathological factors have not a definite role, there is no uniform interpretation. As molecular classification becomes more feasible in the clinical practice, it will provide added value to conventional clinical tumour characteristics in predicting local recurrence in breast cancer and may play an important role as predictor of eventual patient outcomes. PMID:24074774

  5. Molar heat capacity at constant volume of difluoromethane (R32) and pentafluoroethane (R125) from the triple-point temperature to 345 K at pressures to 35 MPa

    SciTech Connect

    Lueddecke, T.O.; Magee, J.W.

    1996-07-01

    Molar heat capacities at constant volume (C{sub v}) of difluoromethane (R32) and pentafluoroethane (R125) were measured with an adiabatic calorimeter. Temperatures ranged from their triple points to 345 K, and pressures up to 35 MPa. Measurements were conducted on the liquid in equilibrium with its vapor and on compressed liquid samples. The samples were of a high purity, verified by chemical analysis of each fluid. For the samples, calorimetric results were obtained for two-phase (C{sub v}{sup (2)}), saturated liquid (C{sub {sigma}} or C {prime}{sub x}), and single-phase (C{sub v}) molar heat capacities. The C{sub {sigma}} data were used to estimate vapor pressures for values less than 0.3 MPa by applying a thermodynamic relationship between the saturated liquid heat capacity and the temperature derivatives of the vapor pressure. The triple-point temperature (T{sub tr}) and the enthalpy of fusion ({Delta}{sub fus}H) were also measured for each substance. The principal sources of uncertainty are the temperature rise measurement and the change-of-volume work adjustment. The expanded uncertainty (at the two-sigma level) for C{sub v} is estimated to be 0.7%, for C{sub v}{sup (2)} it is 0.5%, and for C{sub {sigma}} it is 0.7%.

  6. Intrusion of the overerupted upper left first and second molars by mini-implants with partial-fixed orthodontic appliances: a case report.

    PubMed

    Yao, Chung-Chen Jane; Wu, Chou-Bing; Wu, Hung-Yi; Kok, Sang-Heng; Chang, Hsin-Fu Frank; Chen, Yi-Jane

    2004-08-01

    Overeruption of maxillary molar(s) because of loss of the opposing teeth creates occlusal interference and functional disturbances. To restore proper occlusion, intrusion of the overerupted molars becomes essential before reconstruction can be initiated. A plausible procedure is orthodontic intrusion, which demands calibrated anchorage support from intraoral multiunit teeth and from headgear wear. In this report, we present a simplified and localized version of the orthodontic appliances in conjunction with mini-implants to intrude the overerupted molars. The purpose of using implants as skeletal anchorage was to eliminate the need for patient compliance for headgear wear and to overcome the difficulty resulting from the shortage of anchor teeth. The results showed that the biological responses of the teeth and the surrounding bony structures to the intrusion appeared normal and acceptable. Furthermore, the periodontal health and vitality of the teeth were well maintained even after a one-year follow-up. PMID:15387035

  7. Partial volume correction and image analysis methods for intersubject comparison of FDG-PET studies

    NASA Astrophysics Data System (ADS)

    Yang, Jun

    2000-12-01

    Partial volume effect is an artifact mainly due to the limited imaging sensor resolution. It creates bias in the measured activity in small structures and around tissue boundaries. In brain FDG-PET studies, especially for Alzheimer's disease study where there is serious gray matter atrophy, accurate estimate of cerebral metabolic rate of glucose is even more problematic due to large amount of partial volume effect. In this dissertation, we developed a framework enabling inter-subject comparison of partial volume corrected brain FDG-PET studies. The framework is composed of the following image processing steps: (1)MRI segmentation, (2)MR-PET registration, (3)MR based PVE correction, (4)MR 3D inter-subject elastic mapping. Through simulation studies, we showed that the newly developed partial volume correction methods, either pixel based or ROI based, performed better than previous methods. By applying this framework to a real Alzheimer's disease study, we demonstrated that the partial volume corrected glucose rates vary significantly among the control, at risk and disease patient groups and this framework is a promising tool useful for assisting early identification of Alzheimer's patients.

  8. Slice cutting and partial exposing techniques for three-dimensional texture-based volume rendering

    NASA Astrophysics Data System (ADS)

    Wu, Liangshou; Amin, Viren R.; Ryken, Timothy

    2006-03-01

    Three-dimensional texture-based volume rendering is a technique that treats a 3D volume as a 3D texture, renders multiple 2D view-oriented slices and blends them into the frame buffers. This technique is thoroughly developed in computer graphics and medical visualization, and widely accepted due to the advancement of computer hardware. This research aims at developing fast parallel slice cutting and partial exposing algorithms used in real-time 3D-texture-based volume rendering for image-guided surgery and therapy planning. In texture-based volume rendering, a large amount of slices are needed to render the volume to achieve high quality image, but for real-time interactive volume rendering, the computation time is critical. Instead of repeating the cutting algorithms for each slice against the volume data as conventional cutting algorithms do, the slice cutting algorithm developed in this paper applies the cutting only to the initial slice, and gets the slice vertexes and 3D texture coordinates for all the others based on the distance between the current slice and the initial slice. The new algorithm dramatically reduces the computation time for slice cutting, and eases the generation of sectional view for a volume. Partial exposing is another useful technique used in volume visualization to reveal important but hidden information. Two depth-based partial exposing algorithms are developed and implemented in this paper. Both partial exposing techniques can work with arbitrary complex, but convex, shapes of cutaway object, and their implementations maintain the interactive frame rate for 3D texture-based volume rendering without apparent performance decline compared to non-cutaway rendering.

  9. Retrospective processing of DTI tractography to compensate for partial volume effects

    NASA Astrophysics Data System (ADS)

    Hwang, Darryl; Shetty, Aarti; Rajagopalan, Amrita; Singh, Manbir

    2007-03-01

    Partial volume effects are one of the most common sources of error in diffusion tensor imaging (DTI) tractography. For example, in data from older subjects or Alzheimer's disease probable subjects, the situation is especially exacerbated around the dilated ventricle, which causes erroneous merging of tracts. Rescanning the subject at higher resolution is the best solution, but often times unattainable. We offer a retrospective filtering algorithm, which is purely subtractive, based on a region of interest (ROI) filtering methodology that filters tracts by their shape and seed points. The ROIs are defined using both anatomic images and fractional anisotropy (FA) maps in normalized space allowing for consistency across all subjects. Our algorithm helps correct the partial volume effects by reducing the overestimation of tract length, giving a more accurate regional tract count. The objective of our retrospective algorithm is reclamation of data sets from partial volume effects.

  10. MR Imaging-Guided Partial Volume Correction of PET Data in PET/MR Imaging.

    PubMed

    Erlandsson, Kjell; Dickson, John; Arridge, Simon; Atkinson, David; Ourselin, Sebastien; Hutton, Brian F

    2016-04-01

    Partial volume effects are caused by the limited spatial resolution of the PET system. There is increasing evidence that partial volume correction (PVC) is necessary to guarantee quantitative accuracy in PET; however, there is reluctance to apply PVC routinely in clinical practice, partly because of uncertainty regarding the method of choice. To perform accurate PVC, it is necessary to introduce information from high-resolution anatomic images, such as MR imaging. All the methods rely on accurate coregistration between the anatomic image and the PET image. PET/MR imaging offers clear advantages for PVC and can help alleviate the image registration issues. PMID:26952729

  11. Three-dimensional partial volume segmentation of multispectral magnetic resonance images using stochastic relaxation

    NASA Astrophysics Data System (ADS)

    Johnston, Brian; Atkins, M. Stella; Booth, Kellogg S.

    1994-05-01

    An algorithm has been developed which uses stochastic relaxation in three dimensions to segment brain tissues from images acquired using multiple echo sequences from magnetic resonance imaging (MRI). The initial volume data is assumed to represent a locally dependent Markov random field. Partial volume estimates for each voxel are obtained yielding fractional composition of multiple tissue types for individual voxels. A minimum of user intervention is required to train the algorithm by requiring the manual outlining of regions of interest in a sample image from the volume. Segmentations obtained from multiple echo sequences are determined independently and then combined by forming the product of the probabilities for each tissues type. The implementation has been parallelized using a dataflow programming environment to reduce the computational burden. The algorithm has been used to segment 3D MRI data sets using multiple sclerosis lesions, gray matter, white matter, and cerebrospinal fluid as the partial volumes. Results correspond well with manual segmentations of the same data.

  12. Molar and excess volumes of liquid In-Sb, Mg-Sb, and Pb-Sb alloys

    SciTech Connect

    Hansen, A.R.; Kaminski, M.A. ); Eckert, C.A. )

    1990-04-01

    By a direct Archimedes' technique, volumetric data were obtained for liquid In, Mg, Pb, and Sb and mixtures of In-Sb, Mg-Sb, and Pb-Sb. In this paper the excess volumes for the alloys studied are presented and discussed.

  13. Probabilistic Characterization of Partial Volume Effects in Imaging of Rectangular Objects

    SciTech Connect

    Bulaevskaya, V.

    2015-05-06

    In imaging, a partial volume effect refers to the problem that arises when the system resolution is low relative to the size of the object being imaged [1, 2]. In this setting, it is likely that most voxels occupied by the object are only partially covered, and that the fraction covered in each voxel is low. This makes the problem of object detection and image segmentation very difficult because the algorithms designed for these purposes rely on pixel summary statistics. If the area covered by the object is very low in relatively many of the total number of the voxels the object occupies, these summary statistics may not reach the thresholds required to detect this object. It is thus important to understand the extent of partial volume effect for a given object size and resolution. This technical report focuses on rectangular objects and derives the probability distributions for three quantities for such objects: 1) the number of fully covered voxels, 2) the number of partially covered voxels, and 3) the fractions of the total volume covered in the partially covered voxels. The derivations are first shown for 2-D settings and are then extended to 3-D settings.

  14. Using Microcomputers in the Physical Chemistry Laboratory: A Partial Molal Volumes Experiment.

    ERIC Educational Resources Information Center

    Venugopalan, Mundiyath

    1986-01-01

    Describes a computer program used in an experiment in which the partial molal volumes of sodium chloride solutions are calculated as a function of concentration from densities measured with a pycnometer. The complete program listing (also available from the author on disk) and a sample run are included. (JN)

  15. A Structural Molar Volume Model for Oxide Melts Part II: Li2O-Na2O-K2O-MgO-CaO-MnO-PbO-Al2O3-SiO2 Melts—Ternary and Multicomponent Systems

    NASA Astrophysics Data System (ADS)

    Thibodeau, Eric; Gheribi, Aimen E.; Jung, In-Ho

    2016-04-01

    A structural molar volume model based on the silicate tetrahedral Q-species has been developed to accurately predict the molar volume of molten oxides. In this study, the molar volumes of ternary and multicomponent melts in the Li2O-Na2O-K2O-MgO-CaO-MnO-PbO-Al2O3-SiO2 system are reviewed and compared with the predicted molar volumes from the newly developed structural model. The model can accurately predict the molar volumes using binary model parameters without any ternary or multicomponent parameters. The nonlinear behavior in the molar volume of silicate melts is well predicted by the present model.

  16. A Structural Molar Volume Model for Oxide Melts Part II: Li2O-Na2O-K2O-MgO-CaO-MnO-PbO-Al2O3-SiO2 MeltsTernary and Multicomponent Systems

    NASA Astrophysics Data System (ADS)

    Thibodeau, Eric; Gheribi, Aimen E.; Jung, In-Ho

    2015-12-01

    A structural molar volume model based on the silicate tetrahedral Q-species has been developed to accurately predict the molar volume of molten oxides. In this study, the molar volumes of ternary and multicomponent melts in the Li2O-Na2O-K2O-MgO-CaO-MnO-PbO-Al2O3-SiO2 system are reviewed and compared with the predicted molar volumes from the newly developed structural model. The model can accurately predict the molar volumes using binary model parameters without any ternary or multicomponent parameters. The nonlinear behavior in the molar volume of silicate melts is well predicted by the present model.

  17. An MR image-guided, voxel-based partial volume correction method for PET images

    PubMed Central

    Wang, Hesheng; Fei, Baowei

    2012-01-01

    Purpose: Partial volume effect in positron emission tomography (PET) can cause incorrect quantification of radiopharmaceutical uptake in functional imaging. A PET partial volume correction method is presented to attenuate partial volume blurring and to yield voxel-based corrected PET images. Methods: By modeling partial volume effect as a convolution of point spread function of the PET scanner, the reconstructed PET images are corrected by iterative deconvolution with an edge-preserving smoothness constraint. The constraint is constructed to restore discontinuities extracted from coregistered MR images but maintains the smoothness in radioactivity distribution. The correction is implemented in a Bayesian deconvolution framework and is solved by a conjugate gradient method. The performance of the method was compared with the geometric transfer matrix (GTM) method on a simulated dataset. The method was evaluated on synthesized brain FDG–PET data and phantom MRI–PET experiments. Results: The true PET activity of objects with a size of greater than the full-width at half maximum of the point spread function has been effectively restored in the simulated data. The partial volume correction method is quantitatively comparable to the GTM method. For synthesized FDG–PET with true activity 0 μci/cc for cerebrospinal fluid (CSF), 228 μci/cc for white matter (WM), and 621 μci/cc for gray matter (GM), the method has improved the radioactivity quantification from 186 ± 16 μci/cc to 30 ± 7 μci/cc in CSF, 317 ± 15 μci/cc to 236 ± 10 μci/cc for WM, 438 ± 4 μci/cc to 592 ± 5 μci/cc for GM. Both visual and quantitative assessments show improvement of partial volume correction in the synthesized and phantom experiments. Conclusions: The partial volume correction method improves the quantification of PET images. The method is comparable to the GTM method but does not need MR image segmentation or prior tracer distribution information. The voxel-based method can be particularly useful for combined PET/MRI studies. PMID:22225287

  18. Analysis of partial volume effects on arterial input functions using gradient echo: a simulation study.

    PubMed

    Kjlby, Birgitte F; Mikkelsen, Irene K; Pedersen, Michael; stergaard, Leif; Kiselev, Valerij G

    2009-06-01

    Absolute blood flow and blood volume measurements using perfusion weighted MRI require an accurately measured arterial input function (AIF). Because of limited spatial resolution of MR images, AIF voxels cannot be placed completely within a feeding artery. We present a two-compartment model of an AIF voxel including the relaxation properties of blood and tissue. Artery orientations parallel and perpendicular to the main magnetic field were investigated and AIF voxels were modeled to either include or be situated close to a large artery. The impact of partial volume effects on quantitative perfusion metrics was investigated for the gradient echo pulse sequence at 1.5 T and 3.0 T. It is shown that the tissue contribution broadens and introduces fluctuations in the AIF. Furthermore, partial volume effects bias perfusion metrics in a nonlinear fashion, compromising quantitative perfusion estimates and profoundly effecting local AIF selection. PMID:19365857

  19. Comparison of EM-based and level set partial volume segmentations of MR brain images

    NASA Astrophysics Data System (ADS)

    Tagare, Hemant D.; Chen, Yunmei; Fulbright, Robert K.

    2008-03-01

    EM and level set algorithms are competing methods for segmenting MRI brain images. This paper presents a fair comparison of the two techniques using the Montreal Neurological Institute's software phantom. There are many flavors of level set algorithms for segmentation into multiple regions (multi-phase algorithms, multi-layer algorithms). The specific algorithm evaluated by us is a variant of the multi-layer level set algorithm. It uses a single level set function for segmenting the image into multiple classes and can be run to completion without restarting. The EM-based algorithm is standard. Both algorithms have the capacity to model a variable number of partial volume classes as well as image inhomogeneity (bias field). Our evaluation consists of systematically changing the number of partial volume classes, additive image noise, and regularization parameters. The results suggest that the performances of both algorithms are comparable across noise, number of partial volume classes, and regularization. The segmentation errors of both algorithms are around 5 - 10% for cerebrospinal fluid, gray and white matter. The level set algorithm appears to have a slight advantage for gray matter segmentation. This may be beneficial in studying certain brain diseases (Multiple Sclerosis or Alzheimer's disease) where small changes in gray matter volume are significant.

  20. What approach to brain partial volume correction is best for PET/MRI?

    NASA Astrophysics Data System (ADS)

    Hutton, B. F.; Thomas, B. A.; Erlandsson, K.; Bousse, A.; Reilhac-Laborde, A.; Kazantsev, D.; Pedemonte, S.; Vunckx, K.; Arridge, S. R.; Ourselin, S.

    2013-02-01

    Many partial volume correction approaches make use of anatomical information, readily available in PET/MRI systems but it is not clear what approach is best. Seven novel approaches to partial volume correction were evaluated, including several post-reconstruction methods and several reconstruction methods that incorporate anatomical information. These were compared with an MRI-independent approach (reblurred van Cittert ) and uncorrected data. Monte Carlo PET data were generated for activity distributions representing both 18F FDG and amyloid tracer uptake. Post-reconstruction methods provided the best recovery with ideal segmentation but were particularly sensitive to mis-registration. Alternative approaches performed better in maintaining lesion contrast (unseen in MRI) with good noise control. These were also relatively insensitive to mis-registration errors. The choice of method will depend on the specific application and reliability of segmentation and registration algorithms.

  1. Investigation of partial volume correction methods for brain FDG PET studies

    SciTech Connect

    Yang, J.; Huang, S.C.; Mega, M.; Toga, A.W.; Small, G.W.; Phelps, M.E.; Lin, K.P.

    1996-12-01

    The use of positron emission tomography (PET) in quantitative fluorodeoxyglucose (FDG) studies of aging and dementia has been limited by partial volume effects. A general method for correction of partial volume effects (PVE) in PET involves the following common procedures; segmentation of MRI brain images into gray matter (GM), white matter (WM), cerebral spinal fluid (CSF), and muscle (MS) components; MRI PET registration; and generation of simulated PET images. Afterward, two different approaches can be taken. The first approach derives first a pixel-by-pixel correction map as the ratio of the measured image to the simulated image [with realistic full-width at half-maximum (FWHM)]. The correction map was applied to the MRI segmentation image. Regions of interest (ROI`s) can then be applied to give results free of partial volume effects. The second approach uses the ROI values of the simulated ``pure`` image (with negligible FWHM) and those of the simulated and the measured PET images to correct for the PVE effect. By varying the ratio of radiotracer concentrations for different tissue components, the in-plane FWHM`s of a three-dimensional point spread function, and the ROI size, the authors evaluated the performance of these two approaches in terms of their accuracy and sensitivity to different simulation configurations. The results showed that both approaches are more robust than the approach developed by Muller-Gartner et al., and the second approach is more accurate and more robust than the first. In conclusion, the authors recommend that the second approach should be used on FDG PET images to correct for partial volume effects and to determine whether an apparent change in GM radiotracer concentration is truly due to metabolic changes.

  2. Segmentation of cerebral MRI scans using a partial volume model, shading correction, and an anatomical prior

    NASA Astrophysics Data System (ADS)

    Noe, Aljaz; Kovacic, Stanislav; Gee, James C.

    2001-07-01

    A mixture-model clustering algorithm is presented for robust MRI brain image segmentation in the presence of partial volume averaging. The method uses additional classes to represent partial volume voxels of mixed tissue type in the image. Probability distributions for partial volume voxels are modeled accordingly. The image model also allows for tissue-dependent variance values and voxel neighborhood information is taken into account in the clustering formulation. Additionally we extend the image model to account for a low frequency intensity inhomogeneity that may be present in an image. This so-called shading effect is modeled as a linear combination of polynomial basis functions, and is estimated within the clustering algorithm. We also investigate the possibility of using additional anatomical prior information obtained by registering tissue class template images to the image to be segmented. The final result is the estimated fractional amount of each tissue type present within a voxel in addition to the label assigned to the voxel. A parallel implementation of the method is evaluated using synthetic and real MRI data.

  3. Effects of thoracic gas compression on maximal and partial flow-volume maneuvers.

    PubMed

    Fairshter, R D; Berry, R B; Wilson, A F; Brideshead, T; Mukai, D

    1989-08-01

    Airway hysteresis can be evaluated by comparing maximal (MEFV) and partial (PEFV) expiratory flow-volume curves. The maneuvers are often obtained from pulmonary function systems that are subject to gas-compression artifacts. Because gas-compression artifacts might differentially affect PEFV vs. MEFV curves, we simultaneously obtained MEFV and PEFV curves by use of a spirometer and a volume-displacement plethysmograph (a method not subject to gas-compression artifacts) in normal and asthmatic subjects. Plethysmographic flow rates exceeded spirometric flow rates on all MEFV and PEFV maneuvers. When maximal flow exceeded partial flow (or vice versa) in the plethysmograph, the same result was virtually always observed for spirometric measurements. Alveolar pressure (PA) was higher on MEFV than on PEFV maneuvers in asthmatic subjects; comparisons between PA (on PEFV and MEFV maneuvers) in normal subjects varied at different lung volumes. Ratios of Vmax on PEFV maneuvers to Vmax on MEFV maneuvers (Vmax-p/Vmax-c) obtained from a volume-displacement plethysmograph differ quantitatively from ratios determined in systems subject to gas-compression artifacts; qualitatively, however, failure to account for thoracic gas compression ordinarily will not influence the ability to identify airway hysteresis (or lack thereof) by use of Vmax-p-to-Vmax-c ratios. PMID:2793680

  4. Target Volume Delineation for Partial Breast Radiotherapy Planning: Clinical Characteristics Associated with Low Interobserver Concordance

    SciTech Connect

    Petersen, Ross P.; Truong, Pauline T. Kader, Hosam A.; Berthelet, Eric; Lee, Junella C.; Hilts, Michelle L.; Kader, Adam S.; Beckham, Wayne A.; Olivotto, Ivo A.

    2007-09-01

    Purpose: To examine variability in target volume delineation for partial breast radiotherapy planning and evaluate characteristics associated with low interobserver concordance. Methods and Materials: Thirty patients who underwent planning CT for adjuvant breast radiotherapy formed the study cohort. Using a standardized scale to score seroma clarity and consensus contouring guidelines, three radiation oncologists independently graded seroma clarity and delineated seroma volumes for each case. Seroma geometric center coordinates, maximum diameters in three axes, and volumes were recorded. Conformity index (CI), the ratio of overlapping volume and encompassing delineated volume, was calculated for each case. Cases with CI {<=}0.50 were analyzed to identify features associated with low concordance. Results: The median time from surgery to CT was 42.5 days. For geometric center coordinates, variations from the mean were 0.5-1.1 mm and standard deviations (SDs) were 0.5-1.8 mm. For maximum seroma dimensions, variations from the mean and SDs were predominantly <5 mm, with the largest SDs observed in the medial-lateral axis. The mean CI was 0.61 (range, 0.27-0.84). Five cases had CI {<=}0.50. Conformity index was significantly associated with seroma clarity (p < 0.001) and seroma volume (p < 0.002). Features associated with reduced concordance included tissue stranding from the surgical cavity, proximity to muscle, dense breast parenchyma, and benign calcifications that may be mistaken for surgical clips. Conclusion: Variability in seroma contouring occurred in three dimensions, with the largest variations in the medial-lateral axis. Awareness of clinical features associated with reduced concordance may be applied toward training staff and refining contouring guidelines for partial breast radiotherapy trials.

  5. The impact of oxygen nonstoichiometry upon partial molar thermodynamic quantities in PrBaCo{sub 2}O{sub 5+δ}

    SciTech Connect

    Suntsov, A.Yu.; Leonidov, I.A.; Patrakeev, M.V.; Kozhevnikov, V.L.

    2014-05-01

    The coulometric titration data are utilized in order to calculate changes of oxygen partial entropy and enthalpy in PrBaCo{sub 2}O{sub 5+δ} with variations of oxygen content and temperature. The thermodynamic equilibrium of the cobaltite with the ambient gas phase is analyzed based on the interface of oxygen exchange and oxidation, and the intrinsic reaction of thermal excitation of Co{sup 3+} cations. The partial thermodynamic functions of the movable oxygen in PrBaCo{sub 2}O{sub 5+δ} are shown to be interrelated with the thermodynamic parameters of the defect formation reactions. The existence of a band gap of about 0.4 eV in the electronic spectrum of the cobaltite follows from a favorable comparison of the calculated and experimental dependencies of the partial thermodynamic functions of the movable oxygen. - Graphical abstract: Partial thermodynamic functions of movable oxygen in PrBaCo{sub 2}O{sub 5+δ}. - Highlights: • Thermodynamic functions of oxygen in PrBaCo{sub 2}O{sub 5+δ} are obtained from pO{sub 2}–T–δ diagram. • The defect model is developed to describe changes in thermodynamic functions. • Thermodynamic analysis gives evidence to a band gap in PrBaCo{sub 2}O{sub 5+δ}.

  6. White matter atlas of the human spinal cord with estimation of partial volume effect.

    PubMed

    Lvy, S; Benhamou, M; Naaman, C; Rainville, P; Callot, V; Cohen-Adad, J

    2015-10-01

    Template-based analysis has proven to be an efficient, objective and reproducible way of extracting relevant information from multi-parametric MRI data. Using common atlases, it is possible to quantify MRI metrics within specific regions without the need for manual segmentation. This method is therefore free from user-bias and amenable to group studies. While template-based analysis is common procedure for the brain, there is currently no atlas of the white matter (WM) spinal pathways. The goals of this study were: (i) to create an atlas of the white matter tracts compatible with the MNI-Poly-AMU template and (ii) to propose methods to quantify metrics within the atlas that account for partial volume effect. The WM atlas was generated by: (i) digitalizing an existing WM atlas from a well-known source (Gray's Anatomy), (ii) registering this atlas to the MNI-Poly-AMU template at the corresponding slice (C4 vertebral level), (iii) propagating the atlas throughout all slices of the template (C1 to T6) using regularized diffeomorphic transformations and (iv) computing partial volume values for each voxel and each tract. Several approaches were implemented and validated to quantify metrics within the atlas, including weighted-average and Gaussian mixture models. Proof-of-concept application was done in five subjects for quantifying magnetization transfer ratio (MTR) in each tract of the atlas. The resulting WM atlas showed consistent topological organization and smooth transitions along the rostro-caudal axis. The median MTR across tracts was 26.2. Significant differences were detected across tracts, vertebral levels and subjects, but not across laterality (right-left). Among the different tested approaches to extract metrics, the maximum a posteriori showed highest performance with respect to noise, inter-tract variability, tract size and partial volume effect. This new WM atlas of the human spinal cord overcomes the biases associated with manual delineation and partial volume effect. Combined with multi-parametric data, the atlas can be applied to study demyelination and degeneration in diseases such as multiple sclerosis and will facilitate the conduction of longitudinal and multi-center studies. PMID:26099457

  7. A Partial Volume Effect Correction Tailored for 18F-FDG-PET Oncological Studies

    PubMed Central

    Gallivanone, F.; Canevari, C.; Gianolli, L.; Salvatore, C.; Della Rosa, P. A.; Gilardi, M. C.; Castiglioni, I.

    2013-01-01

    We have developed, optimized, and validated a method for partial volume effect (PVE) correction of oncological lesions in positron emission tomography (PET) clinical studies, based on recovery coefficients (RC) and on PET measurements of lesion-to-background ratio (L/Bm) and of lesion metabolic volume. An operator-independent technique, based on an optimised threshold of the maximum lesion uptake, allows to define an isocontour around the lesion on PET images in order to measure both lesion radioactivity uptake and lesion metabolic volume. RC are experimentally derived from PET measurements of hot spheres in hot background, miming oncological lesions. RC were obtained as a function of PET measured sphere-to-background ratio and PET measured sphere metabolic volume, both resulting from the threshold-isocontour technique. PVE correction of lesions of a diameter ranging from 10?mm to 40?mm and for measured L/Bm from 2 to 30 was performed using measured RC curves tailored at answering the need to quantify a large variety of real oncological lesions by means of PET. Validation of the PVE correction method resulted to be accurate (>89%) in clinical realistic conditions for lesion diameter > 1?cm, recovering >76% of radioactivity for lesion diameter < 1?cm. Results from patient studies showed that the proposed PVE correction method is suitable and feasible and has an impact on a clinical environment. PMID:24163819

  8. Generalized method for partial volume estimation and tissue segmentation in cerebral magnetic resonance images

    PubMed Central

    Khademi, April; Venetsanopoulos, Anastasios; Moody, Alan R.

    2014-01-01

    Abstract. An artifact found in magnetic resonance images (MRI) called partial volume averaging (PVA) has received much attention since accurate segmentation of cerebral anatomy and pathology is impeded by this artifact. Traditional neurological segmentation techniques rely on Gaussian mixture models to handle noise and PVA, or high-dimensional feature sets that exploit redundancy in multispectral datasets. Unfortunately, model-based techniques may not be optimal for images with non-Gaussian noise distributions and/or pathology, and multispectral techniques model probabilities instead of the partial volume (PV) fraction. For robust segmentation, a PV fraction estimation approach is developed for cerebral MRI that does not depend on predetermined intensity distribution models or multispectral scans. Instead, the PV fraction is estimated directly from each image using an adaptively defined global edge map constructed by exploiting a relationship between edge content and PVA. The final PVA map is used to segment anatomy and pathology with subvoxel accuracy. Validation on simulated and real, pathology-free T1 MRI (Gaussian noise), as well as pathological fluid attenuation inversion recovery MRI (non-Gaussian noise), demonstrate that the PV fraction is accurately estimated and the resultant segmentation is robust. Comparison to model-based methods further highlight the benefits of the current approach. PMID:26158022

  9. FIGO Stage III Metastatic Gestational Choriocarcinoma Developed From an Antecedent Partial Hydatidiform Molar Pregnancy Bearing a Numerical Chromosomal Aberration 68, XX: A Case Report and Literature Review.

    PubMed

    Ma, Naili; Litkouhi, Babak; Mannion, Ciaran M

    2016-03-01

    A 36-yr-old, gravida 5 para 4 woman presented with uterine bleeding and was discovered to have a 3.7-cm uterine mass with multiple, bilateral, lung metastases. Six months earlier, the patient was diagnosed with a partial hydatidiform mole that demonstrated a rare chromosomal karyotype 68, XX[12]. The patient's serum ?-human chorionic gonadotropin was elevated from baseline to 12,039 mIU/mL before the treatment. A total hysterectomy was performed and revealed a markedly hemorrhagic, extensively necrotic choriocarcinoma. The tumor mass invaded to a depth of 1/3 of the uterine wall thickness. Cytogenetic analysis of the choriocarcinoma revealed the same 68, XX karyotype, as observed in the antecedent partial hydatidiform mole. A clinical diagnosis of advanced stage invasive choriocarcinoma was rendered, with a risk factor score of 5. Following the development of chemoresistance to a single-agent (methotrexate) regimen, the patient subsequently received 5 cycles of chemotherapy (EMA-CO), without any major complication. She is currently >5 yr posttreatment and is asymptomatic. Her most recent imaging studies, including scans of chest and brain, show no evidence of disease, and her serum ?-human chorionic gonadotropin level has remained consistently below detectable levels. PMID:26352546

  10. Combining MRI with PET for partial volume correction improves image-derived input functions in mice

    PubMed Central

    Evans, Eleanor; Buonincontri, Guido; Izquierdo, David; Methner, Carmen; Hawkes, Rob C.; Ansorge, Richard E.; Krieg, Thomas; Carpenter, T. Adrian; Sawiak, Stephen J.

    2015-01-01

    Accurate kinetic modelling using dynamic PET requires knowledge of the tracer concentration in plasma, known as the arterial input function (AIF). AIFs are usually determined by invasive blood sampling, but this is prohibitive in murine studies due to low total blood volumes. As a result of the low spatial resolution of PET, image-derived input functions (IDIFs) must be extracted from left ventricular blood pool (LVBP) ROIs of the mouse heart. This is challenging because of partial volume and spillover effects between the LVBP and myocardium, contaminating IDIFs with tissue signal. We have applied the geometric transfer matrix (GTM) method of partial volume correction (PVC) to 12 mice injected with 18F-FDG affected by a Myocardial Infarction (MI), of which 6 were treated with a drug which reduced infarction size [1]. We utilised high resolution MRI to assist in segmenting mouse hearts into 5 classes: LVBP, infarcted myocardium, healthy myocardium, lungs/body and background. The signal contribution from these 5 classes was convolved with the point spread function (PSF) of the Cambridge split magnet PET scanner and a non-linear fit was performed on the 5 measured signal components. The corrected IDIF was taken as the fitted LVBP component. It was found that the GTM PVC method could recover an IDIF with less contamination from spillover than an IDIF extracted from PET data alone. More realistic values of Ki were achieved using GTM IDIFs, which were shown to be significantly different (p<0.05) between the treated and untreated groups. PMID:26213413

  11. The molar volume of cubic garnets in the system SiO2-Al2O3-TiO2-Fe2O3-Cr2O3-FeO-MnO-MgO-CaO-Na2O

    NASA Astrophysics Data System (ADS)

    Hamecher, E. A.; Antoshechkina, P. M.; Ghiorso, M. S.; Asimow, P. D.

    2012-12-01

    Garnet is a critical phase that controls major and trace element partitioning at pressures above ~3 GPa during partial melting of the Earth's upper mantle. A molar volume model is calibrated for cubic garnets (space group Ia3d) in the oxide system listed in the title. This model and a recent calibration of spinel molar volume (Hamecher et al., in press, CMP) will be used in calibration of thermodynamic activity-composition models of garnet and pyroxene solid solutions. The activity and molar volume models will be incorporated into the next generation MELTS (Ghiorso & Sack, 1995, CMP) model, xMELTS. A new garnet volume model calibrated with recent in situ high-P, T diffraction data is crucial for accurately modeling key mineralogical transitions in the mantle, e.g., the spinel-garnet transition and the mantle transition zone. Above 5 GPa a majorite component is an essential part of any thermodynamic model of mantle garnets, which to be useful must accurately predict garnet stability with respect to spinel, pyroxene, perovskites, and melt. Our model system contains nine independent end members: Ca3Al2Si3O12, Mg3Al2Si3O12, Fe2+3Al2Si3O12, Mg3Cr2Si3O12, Mg3Fe3+2Si3O12, Mn3Al2Si3O12, Na2(MgSi2)Si3O12, Mg3(TiMg)Si3O12, and cubic majorite component Mg3(MgSi)Si3O12. An inclusive set of end-member components is formed by linear combinations of these explicit end members. Approximately 950 published X-ray diffraction experiments performed on garnets at ambient and in situ high-P, T conditions are used to calibrate end-member equations of state and an excess volume model for this system. Optimal values of the bulk modulus and its pressure derivative are obtained by analyzing published compression and/or ultrasonic data for the end members for which such studies exist; for other end members, density functional theory results are used. For any cubic garnet in this chemical system, the model molar volume is obtained by adding excess volume terms to a linear combination of the nine independent end-member volumes. In the first step of our least squares fitting procedure we calculate volumes of the explicit end members as a function of P and T using the high-T Vinet equation of state. We allow standard state volumes and coefficients of thermal expansion to vary for those independent end members where pure compositional data exist, either for the phase itself or for an appropriate dependent end member. For each dependent end member for which there are data, we calculate the volume of reaction for formation of the phase from the independent end members, ?V. We then fit the binary and mixed composition data, using the singular value analysis method of Lawson & Hanson (1974) to ensure that the calibrated combinations of excess parameters obey the nine ?V constraints from the first step. A key plausibility check on the model results from comparing the predicted T-dependence of the bulk modulus to high-T ultrasonic results that were not used in the calibration. The calculated pressure of the spinel-garnet transition using the new volume models is compared to that obtained with the previous models. The implications our model has for the density of the lithospheric mantle are explored.

  12. Partial volume correction of brain perfusion estimates using the inherent signal data of time-resolved arterial spin labeling.

    PubMed

    Ahlgren, Andr; Wirestam, Ronnie; Petersen, Esben Thade; Sthlberg, Freddy; Knutsson, Linda

    2014-09-01

    Quantitative perfusion MRI based on arterial spin labeling (ASL) is hampered by partial volume effects (PVEs), arising due to voxel signal cross-contamination between different compartments. To address this issue, several partial volume correction (PVC) methods have been presented. Most previous methods rely on segmentation of a high-resolution T1 -weighted morphological image volume that is coregistered to the low-resolution ASL data, making the result sensitive to errors in the segmentation and coregistration. In this work, we present a methodology for partial volume estimation and correction, using only low-resolution ASL data acquired with the QUASAR sequence. The methodology consists of a T1 -based segmentation method, with no spatial priors, and a modified PVC method based on linear regression. The presented approach thus avoids prior assumptions about the spatial distribution of brain compartments, while also avoiding coregistration between different image volumes. Simulations based on a digital phantom as well as in vivo measurements in 10 volunteers were used to assess the performance of the proposed segmentation approach. The simulation results indicated that QUASAR data can be used for robust partial volume estimation, and this was confirmed by the in vivo experiments. The proposed PVC method yielded probable perfusion maps, comparable to a reference method based on segmentation of a high-resolution morphological scan. Corrected gray matter (GM) perfusion was 47% higher than uncorrected values, suggesting a significant amount of PVEs in the data. Whereas the reference method failed to completely eliminate the dependence of perfusion estimates on the volume fraction, the novel approach produced GM perfusion values independent of GM volume fraction. The intra-subject coefficient of variation of corrected perfusion values was lowest for the proposed PVC method. As shown in this work, low-resolution partial volume estimation in connection with ASL perfusion estimation is feasible, and provides a promising tool for decoupling perfusion and tissue volume. PMID:25066601

  13. Kalisphera: an analytical tool to reproduce the partial volume effect of spheres imaged in 3D

    NASA Astrophysics Data System (ADS)

    Tengattini, Alessandro; And, Edward

    2015-09-01

    In experimental mechanics, where 3D imaging is having a profound effect, spheres are commonly adopted for their simplicity and for the ease of their modeling. In this contribution we develop an analytical tool, kalisphera, to produce 3D raster images of spheres including their partial volume effect. This allows us to evaluate the metrological performance of existing image-based measurement techniques (knowing a priori the ground truth). An advanced application of kalisphera is developed here to identify and accurately characterize spheres in real 3D x-ray tomography images with the objective of improving trinarization and contact detection. The effect of the common experimental imperfections is assessed and the overall performance of the tool tested on real images.

  14. A New Approach for Deep Gray Matter Analysis Using Partial-Volume Estimation

    PubMed Central

    Bonnier, Guillaume; Kober, Tobias; Schluep, Myriam; Du Pasquier, Renaud; Krueger, Gunnar; Meuli, Reto

    2016-01-01

    Introduction The existence of partial volume effects in brain MR images makes it challenging to understand physio-pathological alterations underlying signal changes due to pathology across groups of healthy subjects and patients. In this study, we implement a new approach to disentangle gray and white matter alterations in the thalamus and the basal ganglia. The proposed method was applied to a cohort of early multiple sclerosis (MS) patients and healthy subjects to evaluate tissue-specific alterations related to diffuse inflammatory or neurodegenerative processes. Method Forty-three relapsing-remitting MS patients and nineteen healthy controls underwent 3T MRI including: (i) fluid-attenuated inversion recovery, double inversion recovery, magnetization-prepared gradient echo for lesion count, and (ii) T1 relaxometry. We applied a partial volume estimation algorithm to T1 relaxometry maps to gray and white matter local concentrations as well as T1 values characteristic of gray and white matter in the thalamus and the basal ganglia. Statistical tests were performed to compare groups in terms of both global T1 values, tissue characteristic T1 values, and tissue concentrations. Results Significant increases in global T1 values were observed in the thalamus (p = 0.038) and the putamen (p = 0.026) in RRMS patients compared to HC. In the Thalamus, the T1 increase was associated with a significant increase in gray matter characteristic T1 (p = 0.0016) with no significant effect in white matter. Conclusion The presented methodology provides additional information to standard MR signal averaging approaches that holds promise to identify the presence and nature of diffuse pathology in neuro-inflammatory and neurodegenerative diseases. PMID:26845760

  15. MRI-guided brain PET image filtering and partial volume correction.

    PubMed

    Yan, Jianhua; Lim, Jason Chu-Shern; Townsend, David W

    2015-02-01

    Positron emission tomography (PET) image quantification is a challenging problem due to limited spatial resolution of acquired data and the resulting partial volume effects (PVE), which depend on the size of the structure studied in relation to the spatial resolution and which may lead to over or underestimation of the true tissue tracer concentration. In addition, it is usually necessary to perform image smoothing either during image reconstruction or afterwards to achieve a reasonable signal-to-noise ratio. Typically, an isotropic Gaussian filtering (GF) is used for this purpose. However, the noise suppression is at the cost of deteriorating spatial resolution. As hybrid imaging devices such as PET/MRI have become available, the complementary information derived from high definition morphologic images could be used to improve the quality of PET images. In this study, first of all, we propose an MRI-guided PET filtering method by adapting a recently proposed local linear model and then incorporate PVE into the model to get a new partial volume correction (PVC) method without parcellation of MRI. In addition, both the new filtering and PVC are voxel-wise non-iterative methods. The performance of the proposed methods were investigated with simulated dynamic FDG brain dataset and (18)F-FDG brain data of a cervical cancer patient acquired with a simultaneous hybrid PET/MR scanner. The initial simulation results demonstrated that MRI-guided PET image filtering can produce less noisy images than traditional GF and bias and coefficient of variation can be further reduced by MRI-guided PET PVC. Moreover, structures can be much better delineated in MRI-guided PET PVC for real brain data. PMID:25575248

  16. MRI-guided brain PET image filtering and partial volume correction

    NASA Astrophysics Data System (ADS)

    Yan, Jianhua; Chu-Shern Lim, Jason; Townsend, David W.

    2015-02-01

    Positron emission tomography (PET) image quantification is a challenging problem due to limited spatial resolution of acquired data and the resulting partial volume effects (PVE), which depend on the size of the structure studied in relation to the spatial resolution and which may lead to over or underestimation of the true tissue tracer concentration. In addition, it is usually necessary to perform image smoothing either during image reconstruction or afterwards to achieve a reasonable signal-to-noise ratio. Typically, an isotropic Gaussian filtering (GF) is used for this purpose. However, the noise suppression is at the cost of deteriorating spatial resolution. As hybrid imaging devices such as PET/MRI have become available, the complementary information derived from high definition morphologic images could be used to improve the quality of PET images. In this study, first of all, we propose an MRI-guided PET filtering method by adapting a recently proposed local linear model and then incorporate PVE into the model to get a new partial volume correction (PVC) method without parcellation of MRI. In addition, both the new filtering and PVC are voxel-wise non-iterative methods. The performance of the proposed methods were investigated with simulated dynamic FDG brain dataset and 18F-FDG brain data of a cervical cancer patient acquired with a simultaneous hybrid PET/MR scanner. The initial simulation results demonstrated that MRI-guided PET image filtering can produce less noisy images than traditional GF and bias and coefficient of variation can be further reduced by MRI-guided PET PVC. Moreover, structures can be much better delineated in MRI-guided PET PVC for real brain data.

  17. Anatomical-based partial volume correction for low-dose dedicated cardiac SPECT/CT

    NASA Astrophysics Data System (ADS)

    Liu, Hui; Chan, Chung; Grobshtein, Yariv; Ma, Tianyu; Liu, Yaqiang; Wang, Shi; Stacy, Mitchel R.; Sinusas, Albert J.; Liu, Chi

    2015-09-01

    Due to the limited spatial resolution, partial volume effect has been a major degrading factor on quantitative accuracy in emission tomography systems. This study aims to investigate the performance of several anatomical-based partial volume correction (PVC) methods for a dedicated cardiac SPECT/CT system (GE Discovery NM/CT 570c) with focused field-of-view over a clinically relevant range of high and low count levels for two different radiotracer distributions. These PVC methods include perturbation geometry transfer matrix (pGTM), pGTM followed by multi-target correction (MTC), pGTM with known concentration in blood pool, the former followed by MTC and our newly proposed methods, which perform the MTC method iteratively, where the mean values in all regions are estimated and updated by the MTC-corrected images each time in the iterative process. The NCAT phantom was simulated for cardiovascular imaging with 99mTc-tetrofosmin, a myocardial perfusion agent, and 99mTc-red blood cell (RBC), a pure intravascular imaging agent. Images were acquired at six different count levels to investigate the performance of PVC methods in both high and low count levels for low-dose applications. We performed two large animal in vivo cardiac imaging experiments following injection of 99mTc-RBC for evaluation of intramyocardial blood volume (IMBV). The simulation results showed our proposed iterative methods provide superior performance than other existing PVC methods in terms of image quality, quantitative accuracy, and reproducibility (standard deviation), particularly for low-count data. The iterative approaches are robust for both 99mTc-tetrofosmin perfusion imaging and 99mTc-RBC imaging of IMBV and blood pool activity even at low count levels. The animal study results indicated the effectiveness of PVC to correct the overestimation of IMBV due to blood pool contamination. In conclusion, the iterative PVC methods can achieve more accurate quantification, particularly for low count cardiac SPECT studies, typically obtained from low-dose protocols, gated studies, and dynamic applications.

  18. Anatomical-based partial volume correction for low-dose dedicated cardiac SPECT/CT.

    PubMed

    Liu, Hui; Chan, Chung; Grobshtein, Yariv; Ma, Tianyu; Liu, Yaqiang; Wang, Shi; Stacy, Mitchel R; Sinusas, Albert J; Liu, Chi

    2015-09-01

    Due to the limited spatial resolution, partial volume effect has been a major degrading factor on quantitative accuracy in emission tomography systems. This study aims to investigate the performance of several anatomical-based partial volume correction (PVC) methods for a dedicated cardiac SPECT/CT system (GE Discovery NM/CT 570c) with focused field-of-view over a clinically relevant range of high and low count levels for two different radiotracer distributions. These PVC methods include perturbation geometry transfer matrix (pGTM), pGTM followed by multi-target correction (MTC), pGTM with known concentration in blood pool, the former followed by MTC and our newly proposed methods, which perform the MTC method iteratively, where the mean values in all regions are estimated and updated by the MTC-corrected images each time in the iterative process. The NCAT phantom was simulated for cardiovascular imaging with (99m)Tc-tetrofosmin, a myocardial perfusion agent, and (99m)Tc-red blood cell (RBC), a pure intravascular imaging agent. Images were acquired at six different count levels to investigate the performance of PVC methods in both high and low count levels for low-dose applications. We performed two large animal in vivo cardiac imaging experiments following injection of (99m)Tc-RBC for evaluation of intramyocardial blood volume (IMBV). The simulation results showed our proposed iterative methods provide superior performance than other existing PVC methods in terms of image quality, quantitative accuracy, and reproducibility (standard deviation), particularly for low-count data. The iterative approaches are robust for both (99m)Tc-tetrofosmin perfusion imaging and (99m)Tc-RBC imaging of IMBV and blood pool activity even at low count levels. The animal study results indicated the effectiveness of PVC to correct the overestimation of IMBV due to blood pool contamination. In conclusion, the iterative PVC methods can achieve more accurate quantification, particularly for low count cardiac SPECT studies, typically obtained from low-dose protocols, gated studies, and dynamic applications. PMID:26296043

  19. Deciduous molar hypomineralization and molar incisor hypomineralization.

    PubMed

    Elfrink, M E C; ten Cate, J M; Jaddoe, V W V; Hofman, A; Moll, H A; Veerkamp, J S J

    2012-06-01

    This study was embedded in the Generation R Study, a population-based prospective cohort study from fetal life until young adulthood. This study focused on the relationship between Deciduous Molar Hypomineralization (DMH) and Molar Incisor Hypomineralization (MIH). First permanent molars develop during a period similar to that of second primary molars, with possible comparable risk factors for hypomineralization. Children with DMH have a greater risk of developing MIH. Clinical photographs of clean, moist teeth were taken with an intra-oral camera in 6,161 children (49.8% girls; mean age 74.3 mos, SD 5.8). First permanent molars and second primary molars were scored with respect to DMH or MIH. The prevalence of DMH and MIH was 9.0% and 8.7% at child level, and 4.0% and 5.4% at tooth level. The Odds Ratio for MIH based on DMH was 4.4 (95% CI, 3.1-6.4). The relationship between the occurrence of DMH and MIH suggests a shared cause and indicates that, clinically, DMH can be used as a predictor for MIH. PMID:22370445

  20. Distal cervical caries in the mandibular second molar: an indication for the prophylactic removal of third molar teeth? Update.

    PubMed

    McArdle, Louis W; McDonald, Fraser; Jones, Judith

    2014-02-01

    In 2005 we reported the clinical findings of 100 patients who had mandibular third molars removed because of distal cervical caries in the mandibular second molar. The aim of this follow-up study was to find out whether the findings in a new group of patients corroborate those of our previous study. We report on the clinical features of 239 patients (mean (SD) age 32.1 (7.85) years, range 20-65) who had 288 mandibular third molars removed because of distal cervical caries in the second molar. Patients had better dental health than average, and 67% had a DMF (decayed, missing, or filled) score of 5 or less. In 89% of third molars the mesial angulation was between 40 and 80. Distal cervical caries in second molars is a late complication of third molar retention. The prophylactic removal of a partially erupted mesioangular third molar will prevent distal cervical caries forming in the second molar tooth. PMID:24314915

  1. A Structural Molar Volume Model for Oxide Melts Part I: Li2O-Na2O-K2O-MgO-CaO-MnO-PbO-Al2O3-SiO2 Melts—Binary Systems

    NASA Astrophysics Data System (ADS)

    Thibodeau, Eric; Gheribi, Aimen E.; Jung, In-Ho

    2016-04-01

    A structural molar volume model was developed to accurately reproduce the molar volume of molten oxides. As the non-linearity of molar volume is related to the change in structure of molten oxides, the silicate tetrahedral Q-species, calculated from the modified quasichemical model with an optimized thermodynamic database, were used as basic structural units in the present model. Experimental molar volume data for unary and binary melts in the Li2O-Na2O-K2O-MgO-CaO-MnO-PbO-Al2O3-SiO2 system were critically evaluated. The molar volumes of unary oxide components and binary Q-species, which are model parameters of the present structural model, were determined to accurately reproduce the experimental data across the entire binary composition in a wide range of temperatures. The non-linear behavior of molar volume and thermal expansivity of binary melt depending on SiO2 content are well reproduced by the present model.

  2. A Structural Molar Volume Model for Oxide Melts Part I: Li2O-Na2O-K2O-MgO-CaO-MnO-PbO-Al2O3-SiO2 MeltsBinary Systems

    NASA Astrophysics Data System (ADS)

    Thibodeau, Eric; Gheribi, Aimen E.; Jung, In-Ho

    2015-12-01

    A structural molar volume model was developed to accurately reproduce the molar volume of molten oxides. As the non-linearity of molar volume is related to the change in structure of molten oxides, the silicate tetrahedral Q-species, calculated from the modified quasichemical model with an optimized thermodynamic database, were used as basic structural units in the present model. Experimental molar volume data for unary and binary melts in the Li2O-Na2O-K2O-MgO-CaO-MnO-PbO-Al2O3-SiO2 system were critically evaluated. The molar volumes of unary oxide components and binary Q-species, which are model parameters of the present structural model, were determined to accurately reproduce the experimental data across the entire binary composition in a wide range of temperatures. The non-linear behavior of molar volume and thermal expansivity of binary melt depending on SiO2 content are well reproduced by the present model.

  3. A multiresolution image based approach for correction of partial volume effects in emission tomography.

    PubMed

    Boussion, N; Hatt, M; Lamare, F; Bizais, Y; Turzo, A; Cheze-Le Rest, C; Visvikis, D

    2006-04-01

    Partial volume effects (PVEs) are consequences of the limited spatial resolution in emission tomography. They lead to a loss of signal in tissues of size similar to the point spread function and induce activity spillover between regions. Although PVE can be corrected for by using algorithms that provide the correct radioactivity concentration in a series of regions of interest (ROIs), so far little attention has been given to the possibility of creating improved images as a result of PVE correction. Potential advantages of PVE-corrected images include the ability to accurately delineate functional volumes as well as improving tumour-to-background ratio, resulting in an associated improvement in the analysis of response to therapy studies and diagnostic examinations, respectively. The objective of our study was therefore to develop a methodology for PVE correction not only to enable the accurate recuperation of activity concentrations, but also to generate PVE-corrected images. In the multiresolution analysis that we define here, details of a high-resolution image H (MRI or CT) are extracted, transformed and integrated in a low-resolution image L (PET or SPECT). A discrete wavelet transform of both H and L images is performed by using the " trous" algorithm, which allows the spatial frequencies (details, edges, textures) to be obtained easily at a level of resolution common to H and L. A model is then inferred to build the lacking details of L from the high-frequency details in H. The process was successfully tested on synthetic and simulated data, proving the ability to obtain accurately corrected images. Quantitative PVE correction was found to be comparable with a method considered as a reference but limited to ROI analyses. Visual improvement and quantitative correction were also obtained in two examples of clinical images, the first using a combined PET/CT scanner with a lymphoma patient and the second using a FDG brain PET and corresponding T1-weighted MRI in an epileptic patient. PMID:16552110

  4. A multiresolution image based approach for correction of partial volume effects in emission tomography

    NASA Astrophysics Data System (ADS)

    Boussion, N.; Hatt, M.; Lamare, F.; Bizais, Y.; Turzo, A.; Cheze-LeRest, C.; Visvikis, D.

    2006-04-01

    Partial volume effects (PVEs) are consequences of the limited spatial resolution in emission tomography. They lead to a loss of signal in tissues of size similar to the point spread function and induce activity spillover between regions. Although PVE can be corrected for by using algorithms that provide the correct radioactivity concentration in a series of regions of interest (ROIs), so far little attention has been given to the possibility of creating improved images as a result of PVE correction. Potential advantages of PVE-corrected images include the ability to accurately delineate functional volumes as well as improving tumour-to-background ratio, resulting in an associated improvement in the analysis of response to therapy studies and diagnostic examinations, respectively. The objective of our study was therefore to develop a methodology for PVE correction not only to enable the accurate recuperation of activity concentrations, but also to generate PVE-corrected images. In the multiresolution analysis that we define here, details of a high-resolution image H (MRI or CT) are extracted, transformed and integrated in a low-resolution image L (PET or SPECT). A discrete wavelet transform of both H and L images is performed by using the 'à trous' algorithm, which allows the spatial frequencies (details, edges, textures) to be obtained easily at a level of resolution common to H and L. A model is then inferred to build the lacking details of L from the high-frequency details in H. The process was successfully tested on synthetic and simulated data, proving the ability to obtain accurately corrected images. Quantitative PVE correction was found to be comparable with a method considered as a reference but limited to ROI analyses. Visual improvement and quantitative correction were also obtained in two examples of clinical images, the first using a combined PET/CT scanner with a lymphoma patient and the second using a FDG brain PET and corresponding T1-weighted MRI in an epileptic patient.

  5. Differences in Effective Target Volume Between Various Techniques of Accelerated Partial Breast Irradiation

    SciTech Connect

    Shaitelman, Simona F.; Vicini, Frank A.; Grills, Inga S.; Martinez, Alvaro A.; Yan Di; Kim, Leonard H.

    2012-01-01

    Purpose: Different cavity expansions are used to define the clinical target volume (CTV) for accelerated partial breast irradiation (APBI) delivered via balloon brachytherapy (1 cm) vs. three-dimensional conformal radiotherapy (3D-CRT) (1.5 cm). Previous studies have argued that the CTVs generated by these different margins are effectively equivalent. In this study, we use deformable registration to assess the effective CTV treated by balloon brachytherapy on clinically representative 3D-CRT planning images. Methods and Materials: Ten patients previously treated with the MammoSite were studied. Each patient had two computed tomography (CT) scans, one acquired before and one after balloon implantation. In-house deformable registration software was used to deform the MammoSite CTV onto the balloonless CT set. The deformed CTV was validated using anatomical landmarks common to both CT scans. Results: The effective CTV treated by the MammoSite was on average 7% {+-} 10% larger and 38% {+-} 4% smaller than 3D-CRT CTVs created using uniform expansions of 1 and 1.5 cm, respectively. The average effective CTV margin was 1.0 cm, the same as the actual MammoSite CTV margin. However, the effective CTV margin was nonuniform and could range from 5 to 15 mm in any given direction. Effective margins <1 cm were attributable to poor cavity-balloon conformance. Balloon size relative to the cavity did not significantly correlate with the effective margin. Conclusion: In this study, the 1.0-cm MammoSite CTV margin treated an effective volume that was significantly smaller than the 3D-CRT CTV based on a 1.5-cm margin.

  6. Spinal Cord Tolerance to Single-Fraction Partial-Volume Irradiation: A Swine Model

    SciTech Connect

    Medin, Paul M.; Foster, Ryan D.; Kogel, Albert J. van der; Sayre, James W.; McBride, William H.; Solberg, Timothy D.

    2011-01-01

    Purpose: To determine the spinal cord tolerance to single-fraction, partial-volume irradiation in swine. Methods and Materials: A 5-cm-long cervical segment was irradiated in 38-47-week-old Yucatan minipigs using a dedicated, image-guided radiosurgery linear accelerator. The radiation was delivered to a cylindrical volume approximately 5 cm in length and 2 cm in diameter that was positioned lateral to the cervical spinal cord, resulting in a dose distribution with the 90%, 50%, and 10% isodose lines traversing the ipsilateral, central, and contralateral spinal cord, respectively. The dose was prescribed to the 90% isodose line. A total of 26 pigs were stratified into eight dose groups of 12-47 Gy. The mean maximum spinal cord dose was 16.9 {+-} 0.1, 18.9 {+-} 0.1, 21.0 {+-} 0.1, 23.0 {+-} 0.2, and 25.3 {+-} 0.3 Gy in the 16-, 18-, 20-, 22-, and 24-Gy dose groups, respectively. The mean percentage of spinal cord volumes receiving {>=}10 Gy for the same groups were 43% {+-} 3%, 48% {+-} 4%, 51% {+-} 2%, 57% {+-} 2%, and 59% {+-} 4%. The study endpoint was motor neurologic deficit determined by a change in gait during a 1-year follow-up period. Results: A steep dose-response curve was observed with a median effective dose for the maximum dose point of 20.0 Gy (95% confidence interval, 18.3-21.7). Excellent agreement was observed between the occurrence of neurologic change and the presence of histologic change. All the minipigs with motor deficits showed some degree of demyelination and focal white matter necrosis on the irradiated side, with relative sparing of the gray matter. The histologic findings were unremarkable in the minipigs with normal neurologic status. Conclusions: Our results have indicated that for a dose distribution with a steep lateral gradient, the pigs had a lower median effective dose for paralysis than has been observed in rats and more closely resembles that for rats, mice, and guinea pigs receiving uniform spinal cord irradiation.

  7. Partial volume segmentation of brain magnetic resonance images based on maximum a posteriori probability

    SciTech Connect

    Li Xiang; Li Lihong; Lu Hongbing; Liang Zhengrong

    2005-07-15

    Noise, partial volume (PV) effect, and image-intensity inhomogeneity render a challenging task for segmentation of brain magnetic resonance (MR) images. Most of the current MR image segmentation methods focus on only one or two of the above-mentioned effects. The objective of this paper is to propose a unified framework, based on the maximum a posteriori probability principle, by taking all these effects into account simultaneously in order to improve image segmentation performance. Instead of labeling each image voxel with a unique tissue type, the percentage of each voxel belonging to different tissues, which we call a mixture, is considered to address the PV effect. A Markov random field model is used to describe the noise effect by considering the nearby spatial information of the tissue mixture. The inhomogeneity effect is modeled as a bias field characterized by a zero mean Gaussian prior probability. The well-known fuzzy C-mean model is extended to define the likelihood function of the observed image. This framework reduces theoretically, under some assumptions, to the adaptive fuzzy C-mean (AFCM) algorithm proposed by Pham and Prince. Digital phantom and real clinical MR images were used to test the proposed framework. Improved performance over the AFCM algorithm was observed in a clinical environment where the inhomogeneity, noise level, and PV effect are commonly encountered.

  8. Partial volume correction for arterial spin labeling data using spatial-temporal information

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Li, Baojuan; Zhang, Xi; Zhang, Linchuan; Liang, Zhengrong; Lu, Hongbing

    2015-03-01

    Arterial spin labeling (ASL) provides a noninvasive measurement of cerebral blood flow (CBF). Due to relatively low spatial resolution, the accuracy of CBF measurement is affected by the partial volume (PV) effect. In general ASL sequence, multiple scans of perfusion image pairs are acquired temporally to improve the signal to noise ratio. Several spatial PV correction methods have been proposed for the simple averaging of pair-difference images, while the perfusion information of gray matter and white matter existed in multiple image pairs was totally ignored. In this study, a statistical model of perfusion mixtures inside each voxel for the 4D ASL sequence is first proposed. To solve the model, a simplified method is proposed, in which the linear regression (LR) method is first used to obtain initial estimates of spatial correction, then an EM (expectation maximization) method is used to obtain accurate estimation using temporal information. The combination of LR and EM method (EM-LR) can effectively utilize the spatial-temporal information of ASL data for PV correction and provide a theoretical solution to estimate the perfusion mixtures. Both simulated and in vivo data were used to evaluate the performance of proposed method, which demonstrated its superiority on PV correction, edge preserving, and noise suppression.

  9. Finite volume for three-flavour Partially Quenched Chiral Perturbation Theory through NNLO in the meson sector

    NASA Astrophysics Data System (ADS)

    Bijnens, Johan; Rössler, Thomas

    2015-11-01

    We present a calculation of the finite volume corrections to meson masses and decay constants in three flavour Partially Quenched Chiral Perturbation Theory (PQChPT) through two-loop order in the chiral expansion for the flavour-charged (or off-diagonal) pseudoscalar mesons. The analytical results are obtained for three sea quark flavours with one, two or three different masses. We reproduce the known infinite volume results and the finite volume results in the unquenched case. The calculation has been performed using the supersymmetric formulation of PQChPT as well as with a quark flow technique.

  10. Molar heat capacity at constant volume of 1,1-difluoroethane (R152a) and 1,1,1-trifluoroethane (R143a) from the triple-point temperature to 345 k at pressure to 35 MPa

    SciTech Connect

    Magee, J.W.

    1998-09-01

    Molar heat capacities at constant volume (C{sub v}) of 1,1-difluoroethane (R152a) and 1,1,1-trifluoroethane (R143a) have been measured with an adiabatic calorimeter. Temperatures ranged from their triple points to 345 K, and pressures up to 35 MPa. Measurements were conducted on the liquid in equilibrium with its vapor and on compressed liquid samples. The samples were of high purity, verified by chemical analysis of each fluid. For the samples, calorimetric results were obtained for two-phase (C{sub v}{sup (2)}), saturated-liquid (C{sub {sigma}} or C{sub x}{prime}), and single-phase (C{sub v}) molar heat capacities. The C{sub {sigma}} data were used to estimate vapor pressures for values less than 105 kPa by applying a thermodynamic relationship between the saturated liquid heat capacity and the temperature derivatives of the vapor pressure. The triple-point temperature and the enthalpy of fusion were also measured for each substance. The principal sources of uncertainty are the temperature rise measurement and the change-of-volume work adjustment. The expanded relative uncertainty (with a coverage factor k = 2 and thus a two-standard deviation estimate) for C{sub v} is estimated to be 0.7%, for C{sub v}{sup (2)} it is 0.5%, and for C{sub {sigma}} it is 0.7%.

  11. Gray matter myelination of 1555 human brains using partial volume corrected MRI images.

    PubMed

    Shafee, Rebecca; Buckner, Randy L; Fischl, Bruce

    2015-01-15

    The myelin content of the cortex changes over the human lifetime and aberrant cortical myelination is associated with diseases such as schizophrenia and multiple sclerosis. Recently magnetic resonance imaging (MRI) techniques have shown potential in differentiating between myeloarchitectonically distinct cortical regions in vivo. Here we introduce a new algorithm for correcting partial volume effects present in mm-scale MRI images which was used to investigate the myelination pattern of the cerebral cortex in 1555 clinically normal subjects using the ratio of T1-weighted (T1w) and T2-weighted (T2w) MRI images. A significant linear cross-sectional age increase in T1w/T2w estimated myelin was detected across an 18 to 35 year age span (highest value of ~ 1%/year compared to mean T1w/T2w myelin value at 18 years). The cortex was divided at mid-thickness and the value of T1w/T2w myelin calculated for the inner and outer layers separately. The increase in T1w/T2w estimated myelin occurs predominantly in the inner layer for most cortical regions. The ratio of the inner and outer layer T1w/T2w myelin was further validated using high-resolution in vivo MRI scans and also a high-resolution MRI scan of a postmortem brain. Additionally, the relationships between cortical thickness, curvature and T1w/T2w estimated myelin were found to be significant, although the relationships varied across the cortex. We discuss these observations as well as limitations of using the T1w/T2w ratio as an estimate of cortical myelin. PMID:25449739

  12. Gray matter myelination of 1555 human brains using partial volume corrected MRI images

    PubMed Central

    Shafee, Rebecca; Buckner, Randy L.; Fischl, Bruce

    2014-01-01

    The myelin content of the cortex changes over the human lifetime and aberrant cortical myelination is associated with diseases such as schizophrenia and multiple sclerosis. Recently magnetic resonance imaging (MRI) techniques have shown potential in differentiating between myeloarchitectonically distinct cortical regions in vivo. Here we introduce a new algorithm for correcting partial volume effects present in mm-scale MRI images which was used to investigate the myelination pattern of the cerebral cortex in 1555 clinically normal subjects using the ratio of T1-weighted (T1w) and T2-weighted (T2w) MRI images. A significant linear cross-sectional age increase in T1w/T2w estimated myelin was detected across an 18 to 35 year age span (highest value of ~ 1%/year compared to mean T1w/T2w myelin value at 18 years). The cortex was divided at mid-thickness and the value of T1w/T2w myelin calculated for the inner and the outer layers separately. The increase in T1w/T2w estimated myelin occurs predominantly in the inner layer for most cortical regions. The ratio of the inner and outer layer T1w/T12w myelin was further validated using high-resolution in vivo MRI scans and also a high-resolution MRI scan of a postmortem brain. Additionally, the relationships between cortical thickness, curvature and T1w/T2w estimated myelin were found to be significant, although the relationships varied across the cortex. We discuss these observations as well as limitations of using the T1w/T2w ratio as an estimate of cortical myelin. PMID:25449739

  13. Partial volume effect estimation and correction in the aortic vascular wall in PET imaging

    NASA Astrophysics Data System (ADS)

    Burg, S.; Dupas, A.; Stute, S.; Dieudonné, A.; Huet, P.; Le Guludec, D.; Buvat, I.

    2013-11-01

    We evaluated the impact of partial volume effect (PVE) in the assessment of arterial diseases with 18FDG PET. An anthropomorphic digital phantom enabling the modeling of aorta related diseases like atherosclerosis and arteritis was used. Based on this phantom, we performed GATE Monte Carlo simulations to produce realistic PET images with a known organ segmentation and ground truth activity values. Images corresponding to 15 different activity-concentration ratios between the aortic wall and the blood and to 7 different wall thicknesses were generated. Using the PET images, we compared the theoretical wall-to-blood activity-concentration ratios (WBRs) with the measured WBRs obtained with five measurement methods: (1) measurement made by a physician (Expert), (2) automated measurement supposed to mimic the physician measurements (Max), (3) simple correction based on a recovery coefficient (Max-RC), (4) measurement based on an ideal VOI segmentation (Mean-VOI) and (5) measurement corrected for PVE using an ideal geometric transfer matrix (GTM) method. We found that Mean-VOI WBRs values were strongly affected by PVE. WBRs obtained by the physician measurement, by the Max method and by the Max-RC method were more accurate than WBRs obtained with the Mean-VOI approach. However Expert, Max and Max-RC WBRs strongly depended on the wall thickness. Only the GTM corrected WBRs did not depend on the wall thickness. Using the GTM method, we obtained more reproducible ratio values that could be compared across wall thickness. Yet, the feasibility of the implementation of a GTM-like method on real data remains to be studied.

  14. MRI-based correction for PET partial volume effects in the presence of heterogeneity in gray matter radioactivity

    SciTech Connect

    Meltzer, C.C.; Zubieta, J.K.; Links, J.M.

    1994-05-01

    Quantitation of small structures with PET may be inaccurate due to partial volume averaging of surrounding structures. We have previously described a method of correcting PET data for the effects of partial volume averaging on gray matter quantitation. This method may incompletely correct gray matter structures when local tissue concentrations are highly heterogenous. We present an extension of our previous method that by accounting for gray matter heterogeneity, allows for partial volume correction in small structures that can be delineated on MR images. Spoiled gradient echo MR data were acquired coplanar to the PET imaging plane. For each PET slice, 17 contiguous 1.5 mm-thick MR images were tri-segmented into gray matter, white matter, matter maps were created by and the for gray a second step, the structure of for volume and spill-in from surrounding gray and white matter. PET images simulated from MR data from patients with Alzheimer disease and controls demonstrated full recovery of tracer concentration in the amygdala over a range of contrasts (from that of white matter to 4x gray matter) (error = 0.36{plus_minus}0.29%) and sizes (152-725mm{sup 3}) (error = 0.11{plus_minus}0.17%). The method was validated with sphere phantoms and a 5-compartment brain phantom in actual PET acquisitions. This newly developed and validated MR-based partial volume correction algorithm for PET, accurately derives non-homogeneous gray matter radioactivity concentrations and should improve quantitation of subcortical structures.

  15. Accuracy of partial volume effect correction in clinical molecular imaging of dopamine transporter using SPECT

    NASA Astrophysics Data System (ADS)

    Soret, Marine; Alaoui, Jawad; Koulibaly, Pierre M.; Darcourt, Jacques; Buvat, Irne

    2007-02-01

    ObjectivesPartial volume effect (PVE) is a major source of bias in brain SPECT imaging of dopamine transporter. Various PVE corrections (PVC) making use of anatomical data have been developed and yield encouraging results. However, their accuracy in clinical data is difficult to demonstrate because the gold standard (GS) is usually unknown. The objective of this study was to assess the accuracy of PVC. MethodTwenty-three patients underwent MRI and 123I-FP-CIT SPECT. The binding potential (BP) values were measured in the striata segmented on the MR images after coregistration to SPECT images. These values were calculated without and with an original PVC. In addition, for each patient, a Monte Carlo simulation of the SPECT scan was performed. For these simulations where true simulated BP values were known, percent biases in BP estimates were calculated. For the real data, an evaluation method that simultaneously estimates the GS and a quadratic relationship between the observed and the GS values was used. It yields a surrogate mean square error (sMSE) between the estimated values and the estimated GS values. ResultsThe averaged percent difference between BP measured for real and for simulated patients was 0.79.7% without PVC and was -8.514.5% with PVC, suggesting that the simulated data reproduced the real data well enough. For the simulated patients, BP was underestimated by 66.69.3% on average without PVC and overestimated by 11.39.5% with PVC, demonstrating the greatest accuracy of BP estimates with PVC. For the simulated data, sMSE were 27.3 without PVC and 0.90 with PVC, confirming that our sMSE index properly captured the greatest accuracy of BP estimates with PVC. For the real patient data, sMSE was 50.8 without PVC and 3.5 with PVC. These results were consistent with those obtained on the simulated data, suggesting that for clinical data, and despite probable segmentation and registration errors, BP were more accurately estimated with PVC than without. ConclusionPVC was very efficient to greatly reduce the error in BP estimates in clinical imaging of dopamine transporter.

  16. A novel neutron computed tomography partial volume voxel water quantification technique

    NASA Astrophysics Data System (ADS)

    Heller, Arthur Kevin

    Since neutrons are attenuated by small amounts of water, but readily penetrate most metals, neutron imaging is ideal for the observation and quantification of water mass in operating hydrogen-powered polymer electrolyte fuel cells (PEFCs). PEFC's have a special need for non-destructive analysis techniques for the imaging of liquid water because the liquid water stored in the porous media can be a source of reduced performance, degradation and cause more lethargic start-up from freezing conditions. Traditional two-dimensional (2D) neutron radioscopy has been successfully applied to the quantification of liquid water in PEFC's, but it suffers from the drawback of making it difficult to determine the exact "depth" within a PEFC the liquid water mass exists. Neutron computed tomography (NCT) produces a three-dimensional (3D) volumetric reconstruction that offers the ability to determine the exact spatial location of a liquid water mass within a PEFC. This makes possible the isolation of liquid water slugs that can block the channels of either the anode or cathode reactant flow fields. Water mass quantification of these slugs would provide insight into improving PEFC design. Thus, a method was developed for the precise quantification of water mass in neutron computed tomography (NCT) reconstructions. A three-dimensional (3D) volumetric reconstruction is comprised of individual volume elements, or voxels. The gray level value of a voxel represents the total macroscopic cross section, Sigmat, of the material present at the voxel's spatial location. For voxels along interfaces, the gray level represents a combination of Sigmats for the various materials present. The fractional amount of water, also known as a partial volume, represented by such a voxel must be quantified for an accurate result. This calculation requires removing or compensating for the influence of other materials on the voxel's gray level. This is accomplished by background normalizing the raw data used to produce the volumetric reconstruction. The resulting volumetric reconstruction contains voxels that represent only water. Normalizing to the gray level value of a voxel of known water mass produces a matrix of voxels with gray levels that now represent fractional amounts of water. These fractional amounts are tallied and multiplied by the known water mass of the normalizing voxel to determine the total. The NCT water quantification technique was tested using MCNP simulations of samples containing liquid phase water and ice phase water. Quantification of the MCNP simulations yielded results within 0.2% of the theoretical. For liquid phase and ice phase water samples at 30mm from the detector, results were within 2% of the theoretical. The ability to quantify an ice water mixture to within 2% of the theoretical was also demonstrated. For liquid phase water samples at 140mm from the detector, significant error in the quantified water mass, as large as 47%, was observed and determined to be the result of geometric un-sharpness effects and cupping artifacts. Deconvolution of the imaging system's blurring function was performed to correct for the geometric un-sharpness. Results of the devoncolution showed a reduction in the geometric un-sharpness by 14.4% yielding an average increase in quantified water mass of 6.7%. The effects of magnification, cupping artifacts, and geometric unsharpness on the final quantification results were also investigated. Magnification was determined to have no effect while cupping artifacts accounted for 1.4% of the error. Geometric un-sharpness accounted for 45% of the error, making it the dominant source of error.

  17. When Structure Affects Function The Need for Partial Volume Effect Correction in Functional and Resting State Magnetic Resonance Imaging Studies

    PubMed Central

    Dukart, Juergen; Bertolino, Alessandro

    2014-01-01

    Both functional and also more recently resting state magnetic resonance imaging have become established tools to investigate functional brain networks. Most studies use these tools to compare different populations without controlling for potential differences in underlying brain structure which might affect the functional measurements of interest. Here, we adapt a simulation approach combined with evaluation of real resting state magnetic resonance imaging data to investigate the potential impact of partial volume effects on established functional and resting state magnetic resonance imaging analyses. We demonstrate that differences in the underlying structure lead to a significant increase in detected functional differences in both types of analyses. Largest increases in functional differences are observed for highest signal-to-noise ratios and when signal with the lowest amount of partial volume effects is compared to any other partial volume effect constellation. In real data, structural information explains about 25% of within-subject variance observed in degree centrality an established resting state connectivity measurement. Controlling this measurement for structural information can substantially alter correlational maps obtained in group analyses. Our results question current approaches of evaluating these measurements in diseased population with known structural changes without controlling for potential differences in these measurements. PMID:25460595

  18. Ruptured tubal molar pregnancy.

    PubMed

    Yakasai, I A; Adamu, N; Galadanchi, H S

    2012-01-01

    Molar pregnancies in most instances develop within the uterine cavity, but may occur at any site. Ectopic molar pregnancy is a rare event. The objective of this study was to present a case of ruptured tubal molar gestation, discuss its clinical features and ways to improve diagnostic accuracy. A 35-year-old woman presented with features suggestive of ruptured tubal ectopic pregnancy. There was neither any evidence at the time of presentation to suspect a molar gestation, nor ? human chorionic gonadotrophin (?hCG) hormone estimation was done, but only a clearview pregnancy test was carried out. She had total left salpingectomy and histological evaluation of the specimen revealed complete hydatidiform mole. The hCG level normalized within 3 weeks of follow-up. Clinical features of ectopic molar pregnancy may be indistinguishable from non-molar ectopic pregnancy. We recommend ?hCG estimation as well as histological examination of the surgical specimen for all patients coming with features suggestive of ectopic pregnancy. PMID:23238205

  19. Limitation in tidal volume expansion partially determines the intensity of physical activity in COPD.

    PubMed

    Kortianou, Eleni A; Aliverti, Andrea; Louvaris, Zafeiris; Vasilopoulou, Maroula; Nasis, Ioannis; Asimakos, Andreas; Zakynthinos, Spyros; Vogiatzis, Ioannis

    2015-01-01

    In patients with chronic obstructive pulmonary disease (COPD), reduced levels of daily physical activity are associated with the degree of impairment in lung, peripheral muscle, and central hemodynamic function. There is, however, limited evidence as to whether limitations in tidal volume expansion also, importantly, determine daily physical activity levels in COPD. Eighteen consecutive patients with COPD [9 active (forced expiratory volume in 1 s, FEV1: 1.59 0.64 l) with an average daily movement intensity >1.88 m/s(2) and 9 less active patients (FEV1: 1.16 0.41 l) with an average intensity <1.88 m/s(2)] underwent a 4-min treadmill test at a constant speed corresponding to each individual patient's average movement intensity, captured by a triaxial accelerometer during a preceding 7-day period. When chest wall volumes, captured by optoelectronic plethysmography, were expressed relative to comparable levels of minute ventilation (ranging between 14.5 4.3 to 33.5 4.4 l/min), active patients differed from the less active ones in terms of the lower increase in end-expiratory chest wall volume (by 0.15 0.17 vs. 0.45 0.21 l), the greater expansion in tidal volume (by 1.76 0.58 vs. 1.36 0.24 l), and the larger inspiratory reserve chest wall volume (IRVcw: by 0.81 0.25 vs. 0.39 0.27 l). IRVcw (r(2) = 0.420), expiratory flow (r(2) change = 0.174), and Borg dyspnea score (r(2) change = 0.123) emerged as the best contributors, accounting for 71.7% of the explained variance in daily movement intensity. Patients with COPD exhibiting greater ability to expand tidal volume and to maintain adequate inspiratory reserve volume tend to be more physically active. Thus interventions aiming at mitigating restrictions on operational chest wall volumes are expected to enhance daily physical activity levels in COPD. PMID:25398190

  20. Endodontic treatment of molars

    PubMed Central

    Habl, Claudia; Bodenwinkler, Andrea; Strzlinger, Heidi

    2006-01-01

    Objective Commissioned by the German Institute of Medical Documentation and Information (DIMDI) the Austrian Health Institute (BIG) prepared a HTA report on the long-term effectiveness of endodontic treatment (root canal treatment, RCT) of molars. The focus is to examine factors influencing the outcome of endodontic treatment and showing their impact on long-term results. Additionally, economic aspects of root canal treatment in Germany are discussed. Methodology By performing a systematic literature search in 29 databases (e.g. MEDLINE), the Cochrane Library and by hand searching two peer-reviewed endodontic journals the authors could identify 750 relevant articles, of which finally 18 qualified for assessment. Results The findings show that the most relevant factor influencing the long-term outcome of endodontic treatment is the preoperative status of a tooth. The lowest success rates are reported for molars with a preoperative devital or necrotic pulp and persisting periapical lesions (so called periapical disease). Discussion Even if there is no positive selection of patients and the RCT is performed by a normal dentist rather than an endodontist - a fact which is very common - long-term success rates of more then 90% are possible. The overall success rates for endodontic treatment of molars therefore seem to be similar to those of other tooth-types. Conclusions Especially primary, conventional (i.e. non-surgical) root canal treatment is an effective and efficient therapy for endodontically ill molars, especially if no large periapical lesion persists. Nonetheless, a long term successful endodontic therapy requires a thorough assessment of the pre-operative status of the molar and treatment according to established guidelines. PMID:21289954

  1. VAPOR PRESSURES, LIQUID MOLAR VOLUMES, VAPOR NON-IDEALITIES, AND CRITICAL PROPERTIES OF SOME FLUORINATED ETHERS: CF3OCF2OCF3, CF3OCF2CF2H, C-CF2CF2CF2O, CF3OCF2H, AND CF3OCH3; AND OF CCL3F AND CF2CLH

    EPA Science Inventory

    The paper reports results of measurements of vapor pressures, compressibilities, expansivities, and molar volumes of the liquid phase between room temperature and the critical temperature for a series of fluorinated ethers: CF3OCF2-OCF3, CF3OCF2CF2H, c- CF2CF2CF2O, CF3OCF2H, and ...

  2. Improvement of partial volume segmentation for brain tissue on diffusion tensor images using multiple-tensor estimation.

    PubMed

    Kumazawa, Seiji; Yoshiura, Takashi; Honda, Hiroshi; Toyofuku, Fukai

    2013-12-01

    To improve evaluations of cortical and subcortical diffusivity in neurological diseases, it is necessary to improve the accuracy of brain diffusion tensor imaging (DTI) data segmentation. The conventional partial volume segmentation method fails to classify voxels with multiple white matter (WM) fiber orientations such as fiber-crossing regions. Our purpose was to improve the performance of segmentation by taking into account the partial volume effects due to both multiple tissue types and multiple WM fiber orientations. We quantitatively evaluated the overall performance of the proposed method using digital DTI phantom data. Moreover, we applied our method to human DTI data, and compared our results with those of a conventional method. In the phantom experiments, the conventional method and proposed method yielded almost the same root mean square error (RMSE) for gray matter (GM) and cerebrospinal fluid (CSF), while the RMSE in the proposed method was smaller than that in the conventional method for WM. The volume overlap measures between our segmentation results and the ground truth of the digital phantom were more than 0.8 in all three tissue types, and were greater than those in the conventional method. In visual comparisons for human data, the WM/GM/CSF regions obtained using our method were in better agreement with the corresponding regions depicted in the structural image than those obtained using the conventional method. The results of the digital phantom experiment and human data demonstrated that our method improved accuracy in the segmentation of brain tissue data on DTI compared to the conventional method. PMID:23589185

  3. Correction of partial volume effect in (18)F-FDG PET brain studies using coregistered MR volumes: voxel based analysis of tracer uptake in the white matter.

    PubMed

    Coello, Christopher; Willoch, Frode; Selnes, Per; Gjerstad, Leif; Fladby, Tormod; Skretting, Arne

    2013-05-15

    A voxel-based algorithm to correct for partial volume effect in PET brain volumes is presented. This method (named LoReAn) is based on MRI based segmentation of anatomical regions and accurate measurements of the effective point spread function of the PET imaging process. The objective is to correct for the spill-out of activity from high-uptake anatomical structures (e.g. grey matter) into low-uptake anatomical structures (e.g. white matter) in order to quantify physiological uptake in the white matter. The new algorithm is presented and validated against the state of the art region-based geometric transfer matrix (GTM) method with synthetic and clinical data. Using synthetic data, both bias and coefficient of variation were improved in the white matter region using LoReAn compared to GTM. An increased number of anatomical regions doesn't affect the bias (<5%) and misregistration affects equally LoReAn and GTM algorithms. The LoReAn algorithm appears to be a simple and promising voxel-based algorithm for studying metabolism in white matter regions. PMID:23370062

  4. Results and error analysis of a reference voxel normalization method for neutron computed tomography partial volume voxel water quantification

    NASA Astrophysics Data System (ADS)

    Heller, A. K.; Shi, L.; Brenizer, J. S.

    2012-12-01

    Although water quantification using neutron imaging has been successfully applied to water distribution studies of hydrogen-powered fuel cells, the technique produces two-dimensional images, which makes it difficult to determine the exact "depth" inside of an object where an imaged mass of water is located. In contrast, neutron computed tomography (NCT) is an imaging technique that generates a three-dimensional volumetric reconstruction of an object's interior geometry, allowing determination of a structure's exact spatial location. In a reconstruction, determination of the fractional water masses present in partial volume voxels is required for an accurate quantification. Such a NCT partial volume voxel water quantification technique has been developed at The Pennsylvania State University Radiation Science and Engineering Center (RSEC). Several approaches with water-filled cylindrical aluminum samples were used to test the technique: MCNP simulations, samples 30 mm from the detector, and samples 140 mm from the detector. Quantification results were within 0.2% of the theoretical for the MCNP simulations and within 2% for the samples 30 mm from the detector. Significant error, as large as 47%, was seen with the samples 140 mm from the detector. Geometric un-sharpness was determined to be the dominant source of this error. Comparisons between capturing a full set of projections, called true-CT, and a single projection that is duplicated to approximate a full set, called pseudo-CT, were also performed. Results showed pseudo-CT well approximated true-CT, within 1%, for a sample with geometry simple enough that its attenuation map was the same for every viewing angle.

  5. Angle Class II, subdivision, with agenesis of mandibular second molars and extrusion of maxillary second molars *

    PubMed Central

    Tavares, Rubens Rodrigues

    2015-01-01

    This clinical case reports the treatment of an Angle Class II malocclusion in a young woman with a balanced face affected by agenesis of second and third mandibular molars and subsequent extrusion of second maxillary molars. The atypical and peculiar occlusal anomaly led to individualized treatment proposed in order to normalize dental malpositions, with subsequent rehabilitation of edentulous areas by means of a multidisciplinary approach. This case was presented to the Brazilian Board of Orthodontics and Dentofacial Orthopedics (BBO) in partial fulfillment of the requirements for obtaining the title of certified by the BBO. PMID:25992995

  6. Angle Class II, subdivision, with agenesis of mandibular second molars and extrusion of maxillary second molars.

    PubMed

    Tavares, Rubens Rodrigues

    2015-01-01

    This clinical case reports the treatment of an Angle Class II malocclusion in a young woman with a balanced face affected by agenesis of second and third mandibular molars and subsequent extrusion of second maxillary molars. The atypical and peculiar occlusal anomaly led to individualized treatment proposed in order to normalize dental malpositions, with subsequent rehabilitation of edentulous areas by means of a multidisciplinary approach. This case was presented to the Brazilian Board of Orthodontics and Dentofacial Orthopedics (BBO) in partial fulfillment of the requirements for obtaining the title of certified by the BBO. PMID:25992995

  7. Taurodontism in deciduous molars

    PubMed Central

    Bafna, Yash; Kambalimath, H V; Khandelwal, Vishal; Nayak, Prathibha

    2013-01-01

    Taurodont teeth are characterised by large pulp chambers at the expense of roots. An enlarged pulp chamber, apical displacement of the pulpal floor and no constriction at the level of the cement-enamel junction are the characteristic features of taurodont tooth. It appears more frequently as an isolated anomaly but its association with syndromes and other abnormalities have also been reported. Permanent dentition is more commonly affected than deciduous dentition. This paper presents a case report of taurodontism in relation to mandibular deciduous second molars. PMID:23737594

  8. Taurodontism in deciduous molars.

    PubMed

    Bafna, Yash; Kambalimath, H V; Khandelwal, Vishal; Nayak, Prathibha

    2013-01-01

    Taurodont teeth are characterised by large pulp chambers at the expense of roots. An enlarged pulp chamber, apical displacement of the pulpal floor and no constriction at the level of the cement-enamel junction are the characteristic features of taurodont tooth. It appears more frequently as an isolated anomaly but its association with syndromes and other abnormalities have also been reported. Permanent dentition is more commonly affected than deciduous dentition. This paper presents a case report of taurodontism in relation to mandibular deciduous second molars. PMID:23737594

  9. Prosthetic rehabilitation of a hemisected maxillary molar: a rare entity.

    PubMed

    Yadav, Preeti; Tahir, Mohammed; Kumar, M V Sunil; Rao, Harikesh

    2013-09-01

    Gingival recession beyond grade III and grade IV level involving furcation defects can lead to tooth loss if not intervened at appropriate time. The treatment options include scaling and root planing, Furcation-plasty, Tunnel preparation, Root separation and resection. The chief complaint of the patient was pain in the upper left first molar because of grade III furcation involvement. Since it was a four rooted molar, the treatment of choice was hemisection of the tooth and extraction of the distal half following endodontic treatment. As the second molar was mesially tilted the prosthodontic rehabilitation was done with a hybrid prosthesis involving a full coverage conventional porcelain fused to metal retainer on the hemisected molar and a resin bonded partial coverage retainer on the tilted second molar. The resultant prosthesis is termed as "Hybrid prosthesis". PMID:24431763

  10. Fifth alternative for replacement of maxillary first molar.

    PubMed

    Palencar, Adrian J

    2013-01-01

    There are occasions when the patient is missing only one first molar or the first molar is slated for an odontectomy (extraction). Most of the time, there are only four common avenues for replacement: partial removable prosthesis, Maryland bridge, ceramic or ceramic to metal fixed prosthesis and osseo-integrated implant supported crown. In this article, the author discusses the least common avenue for replacement of missing maxillary first molar--an orthodontic closure. He discusses and demonstrates; Maximum, Medium and Minimum Anchorage strategies on acrylic models. Preserving the anchorage is necessary for successful execution of this orthodontic procedure. This demonstration is followed by presentation of the actual case. PMID:23941033

  11. Application of the Third Molar Eruption Predictor to periapical radiographs.

    PubMed

    Vent, I; Schou, S

    2001-06-01

    The aim of this study was to test whether the Third Molar Eruption Predictor, developed for panoramic radiographs, can also be applied to periapical radiographs. The Third Molar Eruption Predictor is a transparent device (US patent 5,816,814), not commercially available, and developed for prediction of future eruption or impaction of third molars. The material consisted of periapical radiographs of mandibular third molars taken from the lateral projection without angulation of the central beam. The radiographs taken at the mean age of 20.6 years (SD +/- 1.4 years) were retrospectively available from a four-year follow-up study of third molars carried out at the University of Copenhagen, Denmark. Initially unerupted or partially erupted third molars (n=43) in 28 dental students were analyzed. Clinical statuses of the third molars were available at baseline and four years later. The device was calibrated using the method of simple proportions and Bayes' Decision Theory. The predictions made with the calibrated device were in conformity with the final clinical outcome in 84% of the cases. It was concluded that the Third Molar Eruption Predictor may also be used on periapical radiographs after calibration of the device. PMID:11480811

  12. VAPOR PRESSURES, LIQUID MOLAR VOLUMES, VAPOR NON- IDEALITIES, AND CRITICAL PROPERTIES OF SOME FLUORINATED ETHERS: CF3OCF2OCF3, CF3OCF2 CF2H, c-CF2CF2CF2O, CF3OCF2H, AND CF3OCH3; AND OF CCl3F AND CF2ClH

    EPA Science Inventory

    Vapor pressures, compressibilities, expansivities, and molar volumes of the liquid phase have been measured between room temperature and the critical temperature for a series of fluorinated ethers: CF3OCF2OCF3, CF3OCF2CF2H, c-CF2CF2CF2O, CF3OCF2H, and CF3OCH3. Vapor-phase non-ide...

  13. Validation of semi-quantitative methods for DAT SPECT: influence of anatomical variability and partial volume effect

    NASA Astrophysics Data System (ADS)

    Gallego, J.; Nierola-Baizn, A.; Cot, A.; Aguiar, P.; Crespo, C.; Falcn, C.; Lomea, F.; Sempau, J.; Pava, J.; Ros, D.

    2015-08-01

    The aim of this work was to evaluate the influence of anatomical variability between subjects and of the partial volume effect (PVE) on the standardized Specific Uptake Ratio (SUR) in [123I]FP-bib SPECT studies. To this end, magnetic resonance (MR) images of 23 subjects with differences in the striatal volume of up to 44% were segmented and used to generate a database of 138 Monte Carlo simulated SPECT studies. Data included normal uptakes and pathological cases. Studies were reconstructed by filtered back projection (FBP) and the ordered-subset expectation-maximization algorithm. Quantification was carried out by applying a reference method based on regions of interest (ROIs) derived from the MR images and ROIs derived from the Automated Anatomical Labelling map. Our results showed that, regardless of anatomical variability, the relationship between calculated and true SUR values for caudate and putamen could be described by a multiple linear model which took into account the spill-over phenomenon caused by PVE ({{R}2}?slant 0.963 for caudate and??0.980 for putamen) and also by a simple linear model (R2???0.952 for caudate and??0.973 for putamen). Calculated values were standardized by inverting both linear systems. Differences between standardized and true values showed that, although the multiple linear model was the best approach in terms of variability ({?2} ???11.79 for caudate and???7.36 for putamen), standardization based on a simple linear model was also suitable ({?2} ???12.44 for caudate and???12.57 for putamen).

  14. Automated quantification of myocardial infarction from MR images by accounting for partial volume effects: animal, phantom, and human study.

    PubMed

    Heiberg, Einar; Ugander, Martin; Engblom, Henrik; Gtberg, Matthias; Olivecrona, Gran K; Erlinge, David; Arheden, Hkan

    2008-02-01

    Ethics committees approved human and animal study components; informed written consent was provided (prospective human study [20 men; mean age, 62 years]) or waived (retrospective human study [16 men, four women; mean age, 59 years]). The purpose of this study was to prospectively evaluate a clinically applicable method, accounting for the partial volume effect, to automatically quantify myocardial infarction from delayed contrast material-enhanced magnetic resonance images. Pixels were weighted according to signal intensity to calculate infarct fraction for each pixel. Mean bias +/- variability (or standard deviation), expressed as percentage left ventricular myocardium (%LVM), were -0.3 +/- 1.3 (animals), -1.2 +/- 1.7 (phantoms), and 0.3 +/- 2.7 (patients), respectively. Algorithm had lower variability than dichotomous approach (2.7 vs 7.7 %LVM, P < .01) and did not differ from interobserver variability for bias (P = .31) or variability (P = .38). The weighted approach provides automatic quantification of myocardial infarction with higher accuracy and lower variability than a dichotomous algorithm. PMID:18055873

  15. Partial volume correction of the microPET blood input function using ensemble learning independent component analysis

    NASA Astrophysics Data System (ADS)

    Su, Kuan-Hao; Lee, Jih-Shian; Li, Jia-Hung; Yang, Yu-Wen; Liu, Ren-Shian; Chen, Jyh-Cheng

    2009-03-01

    Medical images usually suffer from a partial volume effect (PVE), which may degrade the accuracy of any quantitative information extracted from the images. Our aim was to recreate accurate radioactivity concentration and time-activity curves (TACs) by microPET R4 quantification using ensemble learning independent component analysis (EL-ICA). We designed a digital cardiac phantom for this simulation and in order to evaluate the ability of EL-ICA to correct the PVE, the simulated images were convoluted using a Gaussian function (FWHM = 1-4 mm). The robustness of the proposed method towards noise was investigated by adding statistical noise (SNR = 2-16). During further evaluation, another set of cardiac phantoms were generated from the reconstructed images, and Poisson noise at different levels was added to the sinogram. In real experiments, four rat microPET images and a number of arterial blood samples were obtained; these were used to estimate the metabolic rate of FDG (MRFDG). Input functions estimated using the FastICA method were used for comparison. The results showed that EL-ICA could correct PVE in both the simulated and real cases. After correcting for the PVE, the errors for MRFDG, when estimated by the EL-ICA method, were smaller than those when TACs were directly derived from the PET images and when the FastICA approach was used.

  16. A study of shape-dependent partial volume correction in pet imaging using ellipsoidal phantoms fabricated via rapid prototyping

    NASA Astrophysics Data System (ADS)

    Mille, Matthew M.

    Positron emission tomography (PET) with 2-[18F]fluoro-2-deoxy-D-glucose (FDG) is being increasingly recognized as an important tool for quantitative assessment of tumor response because of its ability to capture functional information about the tumor's metabolism. However, despite many advances in PET technology, measurements of tumor radiopharmaceutical uptake in PET are still challenged by issues of accuracy and consistency, thereby compromising the use of PET as a surrogate endpoint in clinical trials. One limiting component of the overall uncertainty in PET is the relatively poor spatial resolution of the images which directly affects the accuracy of the tumor radioactivity measurements. These spatial resolution effects, colloquially known as the partial volume effect (PVE), are a function of the characteristics of the scanner as well as the tumor being imaged. Previous efforts have shown that the PVE depends strongly on the tumor volume and the background-to-tumor activity concentration ratio. The PVE is also suspected to be a function of tumor shape, although to date no systematic study of this effect has been performed. This dissertation seeks to help fill the gap in the current knowledge about the shape-dependence of the PVE by attempting to quantify, through both theoretical calculation and experimental measurement, the magnitude of the shape effect for ellipsoidal tumors. An experimental investigation of the tumor shape effect necessarily requires tumor phantoms of multiple shapes. Hence, a prerequisite for this research was the design and fabrication of hollow tumor phantoms which could be filled uniformly with radioactivity and imaged on a PET scanner. The phantom fabrication was achieved with the aid of stereolithography and included prolate ellipsoids of various axis ratios. The primary experimental method involved filling the tumor phantoms with solutions of 18F whose activity concentrations were known and traceable to primary radioactivity standards held by the National Institute of Standards and Technology (NIST). The tumor phantoms were then placed inside a Jaszczak cylinder (representing the human body) and imaged on a PET scanner located at NIST. This experimental approach allowed for the testing of: (1) The relative difference between tumors phantoms of different shapes, but same volume; (2) The overall accuracy of the PET measurements in terms of a ground truth reference value. Theoretical calculations of the tumor shape effect were also performed by mathematically convolving the phantom shapes with a 3D Gaussian point-spread function, and the results of the calculations were compared with the experimental data. The data show that the shape effect in PET tumor imaging can be as large as 15% for ellipsoid phantoms with axis ratios of 2:1, volume of 1.15 cm 3, and tumor-to-background activity concentration ratio of 9:1. This is explained by a greater loss of counts along the minor axis direction in the ellipsoid tumors compared to that of spheres of the same volume. The results of this PhD research confirm the existence of a tumor shape effect PET imaging. However, except in the case of ellipsoids with major-to-minor axis ratio greater than 2:1, a correction for the effect using recovery coefficients is expected to be challenging because its magnitude is comparable to the repeatability of the PET measurements.

  17. A novel partial volume effects correction technique integrating deconvolution associated with denoising within an iterative PET image reconstruction

    SciTech Connect

    Merlin, Thibaut; Visvikis, Dimitris; Fernandez, Philippe; Lamare, Frederic

    2015-02-15

    Purpose: Partial volume effect (PVE) plays an important role in both qualitative and quantitative PET image accuracy, especially for small structures. A previously proposed voxelwise PVE correction method applied on PET reconstructed images involves the use of Lucy–Richardson deconvolution incorporating wavelet-based denoising to limit the associated propagation of noise. The aim of this study is to incorporate the deconvolution, coupled with the denoising step, directly inside the iterative reconstruction process to further improve PVE correction. Methods: The list-mode ordered subset expectation maximization (OSEM) algorithm has been modified accordingly with the application of the Lucy–Richardson deconvolution algorithm to the current estimation of the image, at each reconstruction iteration. Acquisitions of the NEMA NU2-2001 IQ phantom were performed on a GE DRX PET/CT system to study the impact of incorporating the deconvolution inside the reconstruction [with and without the point spread function (PSF) model] in comparison to its application postreconstruction and to standard iterative reconstruction incorporating the PSF model. The impact of the denoising step was also evaluated. Images were semiquantitatively assessed by studying the trade-off between the intensity recovery and the noise level in the background estimated as relative standard deviation. Qualitative assessments of the developed methods were additionally performed on clinical cases. Results: Incorporating the deconvolution without denoising within the reconstruction achieved superior intensity recovery in comparison to both standard OSEM reconstruction integrating a PSF model and application of the deconvolution algorithm in a postreconstruction process. The addition of the denoising step permitted to limit the SNR degradation while preserving the intensity recovery. Conclusions: This study demonstrates the feasibility of incorporating the Lucy–Richardson deconvolution associated with a wavelet-based denoising in the reconstruction process to better correct for PVE. Future work includes further evaluations of the proposed method on clinical datasets and the use of improved PSF models.

  18. Improved Partial Volume Correction Method for Detecting Brain Activation in Disease Using Arterial Spin Labeling (ASL) fMRI

    PubMed Central

    Bruening, Dylan E; Dharssi, Shazia; Lazar, Ronald M; Marshall, Randolph S; Asllani, Iris

    2016-01-01

    The insight provided by fMRI, particularly BOLD fMRI, has been critical to the understanding of human brain function. Unfortunately, the application of fMRI techniques in clinical research has been held back by several factors. In order for the clinical field to successfully apply fMRI, two main challenges posed by aging and diseased brains need to be overcome: (1) difficulties in signal measurement and interpretation, and (2) partial voluming effects (PVE). Recent work has addressed the first challenge by developing fMRI methods that, in contrast to BOLD, provide a direct measurement of a physiological correlate of function. One such method is Arterial Spin Labeling (ASL) fMRI, which provides images of cerebral blood flow (CBF) in physiologically meaningful units. Although the problems caused by PVE can be mitigated to some degree through the acquisition of high spatial resolution fMRI data, both hardware and experimental design considerations limit this solution. Our team has developed a PVE correction (PVEc) algorithm that produces CBF images that are theoretically independent of tissue content and the associated PVE. The main drawback of the current PVEc method is that it introduces an inherent smoothing of the functional data. This smoothing effect can reduce the sensitivity of the method, complicating the detection of local changes in CBF, such as those due to stroke or activation. Here, we present results from an improved PVEc algorithm (ssPVEc), which uses high-resolution structural space information to correct for the tissue-driven heterogeneity in the ASL signal. We tested the ssPVEc method on ASL images obtained on patients with asymptomatic carotid occlusive disease during rest and motor activation. Our results showed that the sensitivity of the ssPVEc method (defined as the average T-value in the activated region) was at least 1.5 times greater than that of the original, functional space, fsPVEc, for all patients. PMID:26737522

  19. Improved partial volume correction method for detecting brain activation in disease using Arterial Spin Labeling (ASL) fMRI.

    PubMed

    Bruening, Dylan E; Dharssi, Shazia; Lazar, Ronald M; Marshall, Randolph S; Asllani, Iris

    2015-08-01

    The insight provided by fMRI, particularly BOLD fMRI, has been critical to the understanding of human brain function. Unfortunately, the application of fMRI techniques in clinical research has been held back by several factors. In order for the clinical field to successfully apply fMRI, two main challenges posed by aging and diseased brains need to be overcome: (1) difficulties in signal measurement and interpretation, and (2) partial voluming effects (PVE). Recent work has addressed the first challenge by developing fMRI methods that, in contrast to BOLD, provide a direct measurement of a physiological correlate of function. One such method is Arterial Spin Labeling (ASL) fMRI, which provides images of cerebral blood flow (CBF) in physiologically meaningful units. Although the problems caused by PVE can be mitigated to some degree through the acquisition of high spatial resolution fMRI data, both hardware and experimental design considerations limit this solution. Our team has developed a PVE correction (PVEc) algorithm that produces CBF images that are theoretically independent of tissue content and the associated PVE. The main drawback of the current PVEc method is that it introduces an inherent smoothing of the functional data. This smoothing effect can reduce the sensitivity of the method, complicating the detection of local changes in CBF, such as those due to stroke or activation. Here, we present results from an improved PVEc algorithm (ssPVEc), which uses high-resolution structural space information to correct for the tissue-driven heterogeneity in the ASL signal. We tested the ssPVEc method on ASL images obtained on patients with asymptomatic carotid occlusive disease during rest and motor activation. Our results showed that the sensitivity of the ssPVEc method (defined as the average T-value in the activated region) was at least 1.5 times greater than that of the original, functional space, fsPVEc, for all patients. PMID:26737522

  20. A three-dimensional model-based partial volume correction strategy for gated cardiac mouse PET imaging

    NASA Astrophysics Data System (ADS)

    Dumouchel, Tyler; Thorn, Stephanie; Kordos, Myra; DaSilva, Jean; Beanlands, Rob S. B.; deKemp, Robert A.

    2012-07-01

    Quantification in cardiac mouse positron emission tomography (PET) imaging is limited by the imaging spatial resolution. Spillover of left ventricle (LV) myocardial activity into adjacent organs results in partial volume (PV) losses leading to underestimation of myocardial activity. A PV correction method was developed to restore accuracy of the activity distribution for FDG mouse imaging. The PV correction model was based on convolving an LV image estimate with a 3D point spread function. The LV model was described regionally by a five-parameter profile including myocardial, background and blood activities which were separated into three compartments by the endocardial radius and myocardium wall thickness. The PV correction was tested with digital simulations and a physical 3D mouse LV phantom. In vivo cardiac FDG mouse PET imaging was also performed. Following imaging, the mice were sacrificed and the tracer biodistribution in the LV and liver tissue was measured using a gamma-counter. The PV correction algorithm improved recovery from 50% to within 5% of the truth for the simulated and measured phantom data and image uniformity by 5-13%. The PV correction algorithm improved the mean myocardial LV recovery from 0.56 (0.54) to 1.13 (1.10) without (with) scatter and attenuation corrections. The mean image uniformity was improved from 26% (26%) to 17% (16%) without (with) scatter and attenuation corrections applied. Scatter and attenuation corrections were not observed to significantly impact PV-corrected myocardial recovery or image uniformity. Image-based PV correction algorithm can increase the accuracy of PET image activity and improve the uniformity of the activity distribution in normal mice. The algorithm may be applied using different tracers, in transgenic models that affect myocardial uptake, or in different species provided there is sufficient image quality and similar contrast between the myocardium and surrounding structures.

  1. The hydrostatic and hydrodynamic volumes of polyols in aqueous solutions and their sweet taste.

    PubMed

    Lopez Chavez, A; Birch, G G

    1997-04-01

    The tastes and solution properties of sugar alcohols were studied in an attempt to illuminate the mechanism of sweet taste chemoreception. The SMURF method was used to measure tastetime-intensity of aqueous solutions of sugar alcohols and the results were interpreted using the Stevens power function and kinetic parameters. The apparent molar volumes, apparent specific volumes, partial molar volumes, partial specific volumes and intrinsic viscosities of the solutions were studied. Apparent molar volume reflects the size of the molecule in a hydrostatic state whereas intrinsic viscosity gives a measure of the size of the molecules in a hydrodynamic state. Generally the apparent molar volumes of the polyols are 6-13% greater than those of the parent sugars, indicating less interaction with the water structure. Apparent specific volume values can predict taste quality, and the average apparent specific volume for the sugar alcohols studied fits within the central part of the sweet range, i.e. 0.5-0.68 cm3/g, which accords with their ability to elicit a pure sweet taste response. Intensities and persistences of sweetness in the polyols followed the same trend as intrinsic viscosities. PMID:9146905

  2. METHODS DEVELOPMENT FOR ASSESSING AIR POLLUTION CONTROL BENEFITS. VOLUME IV. STUDIES ON PARTIAL EQUILIBRIUM APPROACHES TO VALUATION OF ENVIRONMENTAL AMENITIES

    EPA Science Inventory

    The research presented in this volume of a five volume study of the economic benefits of air pollution control explores various facets of the two central project objectives that have not been given adequate attention in the previous volumes. The valuations developed in these prev...

  3. Partial hydatidiform mole and coexisting viable twin pregnancy.

    PubMed

    Tay, Ee Tein

    2013-12-01

    Twin partial hydatidiform molar pregnancy with a viable fetus is an uncommon occurrence. Presentations of molar pregnancies include vaginal bleeding, unusually elevated ?-human chorionic gonadotropin level, and preeclampsia. Previous descriptions of twin molar and fetus pregnancies in the literature have been described in the outpatient obstetric setting. We present a case of partial molar pregnancy with a viable fetus detected with emergency ultrasound in a pediatric emergency department. PMID:24300477

  4. Molarization of Mandibular Second Premolar

    PubMed Central

    Singh Khinda, Vineet Inder; Kallar, Shiminder; Singh Brar, Gurlal

    2014-01-01

    ABSTRACT Macrodontia (megadontia, megalodontia, mac rodontism) is a rare shape anomaly that has been used to describe dental gigantism. Mandibular second premolars show an elevated variability of crown morphology, as are its eruptive potential and final position in the dental arch. To date, only eight cases of isolated macrodontia of second premolars have been reported in the literature. This case report presents clinical and radiographic findings of unusual and rare case of isolated unilateral molarization of left mandibular second premolar. How to cite this article: Mangla N, Khinda VIS, Kallar S, Brar GS. Molarization of Mandibular Second Premolar. Int J Clin Pediatr Dent 2014;7(2):137-139. PMID:25356014

  5. Molar Incisor Hypomineralization, Prevalence, and Etiology

    PubMed Central

    Allazzam, Sulaiman Mohammed; Alaki, Sumer Madani; El Meligy, Omar Abdel Sadek

    2014-01-01

    Aim. To evaluate the prevalence and possible etiological factors associated with molar incisor hypomineralization (MIH) among a group of children in Jeddah, Saudi Arabia. Methods. A group of 8-12-year-old children were recruited (n = 267) from the Pediatric Dental Clinics at the Faculty of Dentistry, King Abdulaziz University. Children had at least one first permanent molar (FPM), erupted or partially erupted. Demographic information, children's medical history, and pregnancy-related data were obtained. The crowns of the FPM and permanent incisors were examined for demarcated opacities, posteruptive breakdown (PEB), atypical restorations, and extracted FPMs. Children were considered to have MIH if one or more FPM with or without involvement of incisors met the diagnostic criteria. Results. MIH showed a prevalence of 8.6%. Demarcated opacities were the most common form. Maxillary central incisors were more affected than mandibular (P = 0.01). The condition was more prevalent in children with history of illnesses during the first four years of life including tonsillitis (P = 0.001), adenoiditis (P = 0.001), asthma (P = 0.001), fever (P = 0.014), and antibiotics intake (P = 0.001). Conclusions. The prevalence of MIH is significantly associated with childhood illnesses during the first four years of life including asthma, adenoid infections, tonsillitis, fever, and antibiotics intake. PMID:24949012

  6. Noncompliance unilateral maxillary molar distalization:.

    PubMed

    Mavropoulos, Anestis; Sayinsu, Korkmaz; Allaf, Ferdi; Kiliaridis, Stavros; Papadopoulos, Moschos A; Keles, Ahmet Ozlem

    2006-05-01

    The aim of this prospective study was the three-dimensional (3-D) analysis of tooth movements after unilateral upper molar distalization by means of a noncompliance intraoral appliance, the Keles slider. This appliance exerts a distalizing force of 150 g at approximately the level of the center of resistance of the upper first molar. Twelve patients (six girls and six boys with a mean age of 13.1 years) with a unilateral Class II molar relationship participated in the study. Dental casts were taken immediately before placement and after removal of the appliance. The casts were digitized using a 3-D surface laser scanner and superimposed on a predefined area of the palate. The average unilateral upper first molar distal movement was 3.1 mm (range: 2.4 to 5.3 mm). Anchorage loss was expressed by a 2.1 mm (range: 0.8 to 3.8 mm) proclination of the central incisors and a 6.1 degrees mesial inclination of the ipsilateral first premolar (range: 1.7 degrees to 12.3 degrees ). There was approximately 1 mm of midline deviation toward the contralateral side and a 1.6 mm (range: 0.8 to 2.3 mm) buccal displacement of the contralateral first premolar. A substantial variation was observed among patients. Noncompliance unilateral upper molar distalization was an efficient treatment approach. There was, however, a substantial anchorage loss. Case selection is strongly recommended because significant anterior crowding, ectopic canines, or spacing can lead to significant anchorage loss. PMID:16637715

  7. Disruption of erythroid K-Cl cotransporters alters erythrocyte volume and partially rescues erythrocyte dehydration in SAD mice.

    PubMed

    Rust, Marco B; Alper, Seth L; Rudhard, York; Shmukler, Boris E; Vicente, Rubn; Brugnara, Carlo; Trudel, Marie; Jentsch, Thomas J; Hbner, Christian A

    2007-06-01

    K-Cl cotransport activity in rbc is a major determinant of rbc volume and density. Pathologic activation of erythroid K-Cl cotransport activity in sickle cell disease contributes to rbc dehydration and cell sickling. To address the roles of individual K-Cl cotransporter isoforms in rbc volume homeostasis, we disrupted the Kcc1 and Kcc3 genes in mice. As rbc K-Cl cotransport activity was undiminished in Kcc1(-/-) mice, decreased in Kcc3(-/-) mice, and almost completely abolished in mice lacking both isoforms, we conclude that K-Cl cotransport activity of mouse rbc is mediated largely by KCC3. Whereas rbc of either Kcc1(-/-) or Kcc3(-/-) mice were of normal density, rbc of Kcc1(-/-)Kcc3(-/-) mice exhibited defective volume regulation, including increased mean corpuscular volume, decreased density, and increased susceptibility to osmotic lysis. K-Cl cotransport activity was increased in rbc of SAD mice, which are transgenic for a hypersickling human hemoglobin S variant. Kcc1(-/-)Kcc3(-/-) SAD rbc lacked nearly all K-Cl cotransport activity and exhibited normalized values of mean corpuscular volume, corpuscular hemoglobin concentration mean, and K(+) content. Although disruption of K-Cl cotransport rescued the dehydration phenotype of most SAD rbc, the proportion of the densest red blood cell population remained unaffected. PMID:17510708

  8. When Is CT-Based Postoperative Seroma Most Useful to Plan Partial Breast Radiotherapy? Evaluation of Clinical Factors Affecting Seroma Volume and Clarity

    SciTech Connect

    Kader, Hosam A. Truong, Pauline T.; Pai, Rohit; Panades, Miguel; Jones, Stuart; Ansbacher, Will; Olivotto, Ivo A.

    2008-11-15

    Purpose: To evaluate the effect of the time from surgery and other clinical factors on seroma volume and clarity and establish the optimal time to use the computed tomography (CT)-based seroma to plan partial breast irradiation (PBI). Methods and Materials: A total of 205 women with early-stage breast cancer underwent planning CT after breast-conserving surgery. One radiation oncologist contoured the seroma volume and scored the seroma clarity, using a standardized Seroma Clarity Score scale, from 0 (not detectable) to 5 (clearest). Univariate and multivariate analyses were performed to evaluate the associations between the seroma characteristics and the interval from surgery and other clinical factors. Results: The mean interval from surgery to CT was 84 days (standard deviation 59). During postoperative Weeks 3-8, the mean seroma volume decreased from 47 to 30 cm{sup 3}, stabilized during Weeks 9-14 (mean 21) and was involuted beyond 14 weeks (mean 9 cm{sup 3}). The mean seroma clarity score was 3.4 at Weeks 3-8, 2.5 at Weeks 9-14, and 1.6 after 14 weeks. The seroma clarity was greater in patients aged {>=}70 years. The seroma volume and clarity correlated significantly with the volume of excised breast tissue but not with the maximal tumor diameter, surgical re-excision, or chemotherapy use. Conclusion: The optimal time to obtain the planning CT scan for PBI is within 8 weeks after surgery. During Weeks 9-14, the seroma might remain adequately defined in some patients; however, after 14 weeks, alternate strategies are needed to identify the PBI target. The lack of correlation between the seroma volume and tumor size suggests that the CT-based seroma should not be the sole guide for PBI target volume definition.

  9. Dependence of the volume and viscosity of naphthalene-ethanol-octane solutions on composition at 298 K

    NASA Astrophysics Data System (ADS)

    Eliseeva, O. V.; Dyshin, A. A.; Kiselev, M. G.

    2013-03-01

    The solubility of naphthalene in ethanol-octane mixtures was measured by the isothermal saturation method. The solution densities were determined and the partial and apparent molar volumes of naphthalene were calculated. The viscosity was measured with an Ubbelohde viscosimeter with a suspended level. All measurements were performed at 298.15 K. The results were discussed based on interactions in solution.

  10. Geometric morphometric 3D shape analysis and covariation of human mandibular and maxillary first molars.

    PubMed

    Polychronis, Georgios; Christou, Panagiotis; Mavragani, Maria; Halazonetis, Demetrios J

    2013-10-01

    Dental casts of 160 Greek subjects (80 males, 80 females) were scanned by a structured-light scanner. The upper and lower right first molar occlusal surface 3D meshes were processed using geometric morphometric methods. A total of 265 and 274 curve and surface sliding semilandmarks were placed on the upper and lower molar surfaces, respectively. Principal component analysis and partial least square analysis were performed to assess shape parameters. Molars tended to vary between an elongated and a more square form. The first two principal components (PCs), comprising almost 1/3 of molar shape variation, were related to mesiodistal-buccolingual ratios and relative cusp position. Distal cusps displayed the greatest shape variability. Molars of males were larger than those of females (2.8 and 3.2% for upper and lower molars respectively), but no shape dimorphism was observed. Upper and lower molar sizes were significantly correlated (r(2) = 0.689). Allometry was observed for both teeth. Larger lower molars were associated with shorter cusps, expansion of the distal cusp, and constriction of the mesial cusps (predicted variance 3.25%). Upper molars displayed weaker allometry (predicted variance 1.59%). Upper and lower molar shape covariation proved significant (RV = 17.26%, P < 0.0001). The main parameter of molar covariation in partial least square axis 1, contributing to 30% of total covariation, was cusp height, in contrast to the primary variability traits exhibited by PC1 and PC2. The aim of this study was to evaluate shape variation and covariation, including allometry and sexual dimorphism, of maxillary and mandibular first permanent molar occlusal surfaces. PMID:24009105

  11. Fracture behavior of human molars.

    PubMed

    Keown, Amanda J; Lee, James J-W; Bush, Mark B

    2012-12-01

    Despite the durability of human teeth, which are able to withstand repeated loading while maintaining form and function, they are still susceptible to fracture. We focus here on longitudinal fracture in molar teeth-channel-like cracks that run along the enamel sidewall of the tooth between the gum line (cemento-enamel junction-CEJ) and the occlusal surface. Such fractures can often be painful and necessitate costly restorative work. The following study describes fracture experiments made on molar teeth of humans in which the molars are placed under axial compressive load using a hard indenting plate in order to induce longitudinal cracks in the enamel. Observed damage modes include fractures originating in the occlusal region ('radial-median cracks') and fractures emanating from the margin of the enamel in the region of the CEJ ('margin cracks'), as well as 'spalling' of enamel (the linking of longitudinal cracks). The loading conditions that govern fracture behavior in enamel are reported and observations made of the evolution of fracture as the load is increased. Relatively low loads were required to induce observable crack initiation-approximately 100 N for radial-median cracks and 200 N for margin cracks-both of which are less than the reported maximum biting force on a single molar tooth of several hundred Newtons. Unstable crack growth was observed to take place soon after and occurred at loads lower than those calculated by the current fracture models. Multiple cracks were observed on a single cusp, their interactions influencing crack growth behavior. The majority of the teeth tested in this study were noted to exhibit margin cracks prior to compression testing, which were apparently formed during the functional lifetime of the tooth. Such teeth were still able to withstand additional loading prior to catastrophic fracture, highlighting the remarkable damage containment capabilities of the natural tooth structure. PMID:22956116

  12. Measurement of D2 dopamine receptor-specific carbon-11-YM-09151-2 binding in the canine brain by PET: Importance of partial volume correction

    SciTech Connect

    Hatazawa, J.; Hatano, K.; Ishiwata, K.; Itoh, M.; Ido, T.; Kawashima, K.; Meguro, K.; Watanuki, S.; Seo, S. )

    1991-04-01

    Carbon-11-YM-09151-2 binds highly selectively to D2 dopamine receptors in the brain. Using this ligand, D2 dopamine receptor density (Bmax) and affinity (Kd) in canine striatum were measured. After administering various doses of the ligand in nine experiments, regional uptake was followed by repeated PET scanning for up to 80 min. D2 dopamine receptor specific binding at equilibrium was defined as striatal minus occipital activity after partial volume correction. Bmax and Kd were estimated by Scatchard analysis to be 40.3 pmole/ml of tissue and 22.9 nM, respectively. When a low mass dose of the ligand was administered, the bound-to-free ligand ratio in the striatum at equilibrium was consistent with the Bmax/Kd value obtained from the Scatchard analysis. The present study demonstrates the importance of partial volume correction and the Bmax/Kd measurement in a single PET study with carbon-11-YM-09151-2.

  13. Densities and apparent molar volumes of atmospherically important electrolyte solutions. 1. The solutes H2SO4, HNO3, HCl, Na2SO4, NaNO3, NaCl, (NH4)2SO4, NH4NO3, and NH4Cl from 0 to 50 C, including extrapolations to very low temperature and to the pure liquid state, and NaHSO4, NaOH, and NH3 at 25 C.

    PubMed

    Clegg, S L; Wexler, A S

    2011-04-21

    Calculations of the size and density of atmospheric aerosols are complicated by the fact that they can exist at concentrations highly supersaturated with respect to dissolved salts and supercooled with respect to ice. Densities and apparent molar volumes of solutes in aqueous solutions containing the solutes H(2)SO(4), HNO(3), HCl, Na(2)SO(4), NaNO(3), NaCl, (NH(4))(2)SO(4), NH(4)NO(3), and NH(4)Cl have been critically evaluated and represented using fitted equations from 0 to 50 C or greater and from infinite dilution to concentrations saturated or supersaturated with respect to the dissolved salts. Using extrapolated densities of high-temperature solutions and melts, the relationship between density and concentration is extended to the hypothetical pure liquid solutes. Above a given reference concentration of a few mol kg(-1), it is observed that density increases almost linearly with decreasing temperature, and comparisons with available data below 0 C suggest that the fitted equations for density can be extrapolated to very low temperatures. As concentration is decreased below the reference concentration, the variation of density with temperature tends to that of water (which decreases as temperature is reduced below 3.98 C). In this region below the reference concentration, and below 0 C, densities are calculated using extrapolated apparent molar volumes which are constrained to agree at the reference concentrations with an equation for the directly fitted density. Calculated volume properties agree well with available data at low temperatures, for both concentrated and dilute solutions. Comparisons are made with literature data for temperatures of maximum density. Apparent molar volumes at infinite dilution are consistent, on a single ion basis, to better than 0.1 cm(3) mol(-1) from 0 to 50 C. Volume properties of aqueous NaHSO(4), NaOH, and NH(3) have also been evaluated, at 25 C only. In part 2 of this work (ref 1 ) an ion interaction (Pitzer) model has been used to calculate apparent molar volumes of H(2)SO(4) in 0-3 mol kg(-1) aqueous solutions of the pure acid and to represent directly the effect of the HSO(4)(-) ? H(+) + SO(4)(2-) reaction. The results are incorporated into the treatment of aqueous H(2)SO(4) density described here. Densities and apparent molar volumes from -20 to 50 C, and from 0 to 100 wt % of solute, are tabulated for the electrolytes listed in the title and have also been incorporated into the extended aerosol inorganics model (E-AIM, http://www.aim.env.uea.ac.uk/aim/aim.php) together with densities of the solid salts and hydrates. PMID:21438504

  14. Molar versus as a paradigm clash.

    PubMed

    Baum, W M

    2001-05-01

    The molar view of behavior arose in response to the demonstrated inadequacy of explanations based on contiguity. Although Dinsmoor's (2001) modifications to two-factor theory render it irrefutable, a more basic criticism arises when we see that the molar and molecular views differ paradigmatically. The molar view has proven more productive. PMID:11453623

  15. Impact of Increasing Margin Around the Lumpectomy Cavity to Define the Planning Target Volume for 3D Conformal External Beam Accelerated Partial Breast Irradiation

    SciTech Connect

    Cox, Brett W.; Horst, Kathleen C. Thornton, Sherri; Dirbas, Frederick M.

    2007-01-01

    The purpose of this study was to evaluate the dose to normal tissues as a function of increasing margins around the lumpectomy cavity in accelerated partial breast irradiation (APBI) using 3D-conformal radiotherapy (3DCRT). Eight patients with Stage 0-I breast cancer underwent treatment planning for 3DCRT APBI. The clinical target volume (CTV) was defined as a 15-mm expansion around the cavity limited by the chest wall and skin. Three planning target volumes (PTV1, PTV2, PTV3) were generated for each patient using a 0, 5-, and 10-mm expansion around the CTV, for a total margin of 15, 20, and 25 mm. Three treatment plans were generated for every patient using the 3 PTVs, and dose-volume analysis was performed for each plan. For each 5-mm increase in margin, the mean PTV:total breast volume ratio increased 10% and the relative increase in the mean ipsilateral breast dose was 15%. The mean volume of ipsilateral breast tissue receiving 75%, 50%, and 25% of the prescribed dose increased 6% to 7% for every 5 mm increase in PTV margin. Compared to lesions located in the upper outer quadrant, plans for medially located tumors revealed higher mean ipsilateral breast doses and 20% to 22% more ipsilateral breast tissue encompassed by the 25% IDL. The use of 3DCRT for APBI delivers higher doses to normal breast tissue as the PTV increases around the lumpectomy cavity. Efforts should be made to minimize the overall PTV when this technique is used. Ongoing studies will be necessary to determine the clinical relevance of these findings.

  16. Reducing the influence of the partial volume effect on SPECT activity quantitation with 3D modelling of spatial resolution in iterative reconstruction

    NASA Astrophysics Data System (ADS)

    Pretorius, P. H.; King, M. A.; Pan, T.-S.; de Vries, D. J.; Glick, S. J.; Byrne, C. L.

    1998-02-01

    Quantitative parameters such as the maximum and total counts in a volume are influenced by the partial volume effect. The magnitude of this effect varies with the non-stationary and anisotropic spatial resolution in SPECT slices. The objective of this investigation was to determine whether iterative reconstruction which includes modelling of the three-dimensional (3D) spatial resolution of SPECT imaging can reduce the impact of the partial volume effect on the quantitation of activity compared with filtered backprojection (FBP) techniques which include low-pass, and linear restoration filtering using the frequency distance relationship (FDR). The iterative reconstruction algorithms investigated were maximum-likelihood expectation-maximization (MLEM), MLEM with ordered subset acceleration (ML-OS), and MLEM with acceleration by the rescaled-block-iterative technique (ML-RBI). The SIMIND Monte Carlo code was used to simulate small hot spherical objects in an elliptical cylinder with and without uniform background activity as imaged by a low-energy ultra-high-resolution (LEUHR) collimator. Centre count ratios (CCRs) and total count ratios (TCRs) were determined as the observed counts over true counts. CCRs were unstable while TCRs had a bias of for all iterative techniques. The variance in the TCRs for ML-OS and ML-RBI was clearly elevated over that of MLEM, with ML-RBI having the smaller elevation. TCRs obtained with FDR-Wiener filtering had a larger bias than any of the iterative reconstruction methods but near stationarity is also reached. Butterworth filtered results varied by 9.7% from the centre to the edge. The addition of background has an influence on the convergence rate and noise properties of iterative techniques.

  17. PET imaging of thin objects: measuring the effects of positron range and partial-volume averaging in the leag of Nicotiana Tabacum

    SciTech Connect

    Alexoff, D.L.; Alexoff, D.L.; Dewey, S.L.; Vaska, P.; Krishnamoorthy, S.; Ferrieri, R.; Schueller, M.; Schlyer, D.; Fowler, J.S.

    2011-03-01

    PET imaging in plants is receiving increased interest as a new strategy to measure plant responses to environmental stimuli and as a tool for phenotyping genetically engineered plants. PET imaging in plants, however, poses new challenges. In particular, the leaves of most plants are so thin that a large fraction of positrons emitted from PET isotopes ({sup 18}F, {sup 11}C, {sup 13}N) escape while even state-of-the-art PET cameras have significant partial-volume errors for such thin objects. Although these limitations are acknowledged by researchers, little data have been published on them. Here we measured the magnitude and distribution of escaping positrons from the leaf of Nicotiana tabacum for the radionuclides {sup 18}F, {sup 11}C and {sup 13}N using a commercial small-animal PET scanner. Imaging results were compared to radionuclide concentrations measured from dissection and counting and to a Monte Carlo simulation using GATE (Geant4 Application for Tomographic Emission). Simulated and experimentally determined escape fractions were consistent. The fractions of positrons (mean {+-} S.D.) escaping the leaf parenchyma were measured to be 59 {+-} 1.1%, 64 {+-} 4.4% and 67 {+-} 1.9% for {sup 18}F, {sup 11}C and {sup 13}N, respectively. Escape fractions were lower in thicker leaf areas like the midrib. Partial-volume averaging underestimated activity concentrations in the leaf blade by a factor of 10 to 15. The foregoing effects combine to yield PET images whose contrast does not reflect the actual activity concentrations. These errors can be largely corrected by integrating activity along the PET axis perpendicular to the leaf surface, including detection of escaped positrons, and calculating concentration using a measured leaf thickness.

  18. Hypometabolism in Brain of Cognitively Normal Patients with Depressive Symptoms is Accompanied by Atrophy-Related Partial Volume Effects.

    PubMed

    Brendel, Matthias; Reinisch, Veronika; Kalinowski, Eva; Levin, Johannes; Delker, Andreas; Därr, Sonja; Pogarell, Oliver; Förster, Stefan; Bartenstein, Peter; Rominger, Axel; Alzheimer's Disease Neuroimaging Initiative

    2016-01-01

    Late life depression (LLD) even in subsyndromal stages shows high conversion rates from cognitively normal (CN) to mild cognitive impairment (MCI). Results of [(18)F]-fluorodesoxyglucose positron-emission-tomography (FDG-PET) were inconsistent in LLD patients, whereas atrophy was repeatedly described. Therefore, we set out to investigate FDG metabolism and the effect of atrophy correction (PVEC) in geriatric CN patients with depressive symptoms. 21 CN subjects with positive item for the depression category (DEP) in the Neuropsychiatric-Inventory-Questionnaire and 29 CN subjects with an absent depression item (NON-DEP) were selected from the ADNI cohort. FDG-PETs were analyzed in individual PET space using volumes-of-interest (VOI) and statistical-parametric-mapping (SPM) approaches. VOI- and MRI-based PVEC were applied to PET data. DEP subjects showed significant hypometabolism in fronto-temporal cortices and the posterior cingulate cortex (PCC) when contrasted against NON-DEP in uncorrected data. Both in VOI- and SPM-based approaches PVEC eliminated significance in PCC, while fronto-temporal regions remained significant or even attained significance such as in case of the left amygdala. Subsyndromally depressed CN subjects had decreased FDG metabolism in mood-related brain regions, which may be relevant to their elevated risk for conversion from CN to MCI. Methodological advances in PET analyses should be considered in future studies as PVEC relevantly changed results of FDG-PET for detecting apparent metabolic differences between DEP and NON-DEP subjects. Furthermore, VOI-based analyses in individual PET space will allow a more accurate consideration of variability in anatomy, especially in subcortical regions. PMID:26971944

  19. The Effect of Dose-Volume Parameters and Interfraction Interval on Cosmetic Outcome and Toxicity After 3-Dimensional Conformal Accelerated Partial Breast Irradiation

    SciTech Connect

    Leonard, Kara Lynne; Hepel, Jaroslaw T.; Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island ; Hiatt, Jessica R.; Dipetrillo, Thomas A.; Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island ; Price, Lori Lyn; Wazer, David E.; Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island

    2013-03-01

    Purpose: To evaluate dose-volume parameters and the interfraction interval (IFI) as they relate to cosmetic outcome and normal tissue effects of 3-dimensional conformal radiation therapy (3D-CRT) for accelerated partial breast irradiation (APBI). Methods and Materials: Eighty patients were treated by the use of 3D-CRT to deliver APBI at our institutions from 2003-2010 in strict accordance with the specified dose-volume constraints outlined in the National Surgical Adjuvant Breast and Bowel Project B39/Radiation Therapy Oncology Group 0413 (NSABP-B39/RTOG 0413) protocol. The prescribed dose was 38.5 Gy in 10 fractions delivered twice daily. Patients underwent follow-up with assessment for recurrence, late toxicity, and overall cosmetic outcome. Tests for association between toxicity endpoints and dosimetric parameters were performed with the chi-square test. Univariate logistic regression was used to evaluate the association of interfraction interval (IFI) with these outcomes. Results: At a median follow-up time of 32 months, grade 2-4 and grade 3-4 subcutaneous fibrosis occurred in 31% and 7.5% of patients, respectively. Subcutaneous fibrosis improved in 5 patients (6%) with extended follow-up. Fat necrosis developed in 11% of women, and cosmetic outcome was fair/poor in 19%. The relative volume of breast tissue receiving 5%, 20%, 50%, 80%, and 100% (V5-V100) of the prescribed dose was associated with risk of subcutaneous fibrosis, and the volume receiving 50%, 80%, and 100% (V50-V100) was associated with fair/poor cosmesis. The mean IFI was 6.9 hours, and the minimum IFI was 6.2 hours. The mean and minimum IFI values were not significantly associated with late toxicity. Conclusions: The incidence of moderate to severe late toxicity, particularly subcutaneous fibrosis and fat necrosis and resulting fair/poor cosmesis, remains high with continued follow-up. These toxicity endpoints are associated with several dose-volume parameters. Minimum and mean IFI values were not associated with late toxicity.

  20. Mandibular molar root morphology in Neanderthals and Late Pleistocene and recent Homo sapiens.

    PubMed

    Kupczik, Kornelius; Hublin, Jean-Jacques

    2010-11-01

    Neanderthals have a distinctive suite of dental features, including large anterior crown and root dimensions and molars with enlarged pulp cavities. Yet, there is little known about variation in molar root morphology in Neanderthals and other recent and fossil members of Homo. Here, we provide the first comprehensive metric analysis of permanent mandibular molar root morphology in Middle and Late Pleistocene Homo neanderthalensis, and Late Pleistocene (Aterian) and recent Homo sapiens. We specifically address the question of whether root form can be used to distinguish between these groups and assess whether any variation in root form can be related to differences in tooth function. We apply a microtomographic imaging approach to visualise and quantify the external and internal dental morphologies of both isolated molars and molars embedded in the mandible (n=127). Univariate and multivariate analyses reveal both similarities (root length and pulp volume) and differences (occurrence of pyramidal roots and dental tissue volume proportion) in molar root morphology among penecontemporaneous Neanderthals and Aterian H. sapiens. In contrast, the molars of recent H. sapiens are markedly smaller than both Pleistocene H. sapiens and Neanderthals, but share with the former the dentine volume reduction and a smaller root-to-crown volume compared with Neanderthals. Furthermore, we found the first molar to have the largest average root surface area in recent H. sapiens and Neanderthals, although in the latter the difference between M(1) and M(2) is small. In contrast, Aterian H. sapiens root surface areas peak at M(2). Since root surface area is linked to masticatory function, this suggests a distinct occlusal loading regime in Neanderthals compared with both recent and Pleistocene H. sapiens. PMID:20719359

  1. A Prospective Pathologic Study to Define the Clinical Target Volume for Partial Breast Radiation Therapy in Women With Early Breast Cancer

    SciTech Connect

    Nguyen, Brandon T.; Deb, Siddhartha; Victorian Cancer Biobank, Cancer Council of Victoria, Carlton, Victoria ; Fox, Stephen; Hill, Prudence; Collins, Marnie; Chua, Boon H.; University of Melbourne, Parkville, Victoria

    2012-12-01

    Purpose: To determine an appropriate clinical target volume for partial breast radiation therapy (PBRT) based on the spatial distribution of residual invasive and in situ carcinoma after wide local excision (WLE) for early breast cancer or ductal carcinoma in situ (DCIS). Methods and Materials: We performed a prospective pathologic study of women potentially eligible for PBRT who had re-excision and/or completion mastectomy after WLE for early breast cancer or DCIS. A pathologic assessment protocol was used to determine the maximum radial extension (MRE) of residual carcinoma from the margin of the initial surgical cavity. Women were stratified by the closest initial radial margin width: negative (>1 mm), close (>0 mm and {<=}1 mm), or involved. Results: The study population was composed of 133 women with a median age of 59 years (range, 27-82 years) and the following stage groups: 0 (13.5%), I (40.6%), II (38.3%), and III (7.5%). The histologic subtypes of the primary tumor were invasive ductal carcinoma (74.4%), invasive lobular carcinoma (12.0%), and DCIS alone (13.5%). Residual carcinoma was present in the re-excision and completion mastectomy specimens in 55.4%, 14.3%, and 7.2% of women with an involved, close, and negative margin, respectively. In the 77 women with a noninvolved radial margin, the MRE of residual disease, if present, was {<=}10 mm in 97.4% (95% confidence interval 91.6-99.5) of cases. Larger MRE measurements were significantly associated with an involved margin (P<.001), tumor size >30 mm (P=.03), premenopausal status (P=.03), and negative progesterone receptor status (P=.05). Conclusions: A clinical target volume margin of 10 mm would encompass microscopic residual disease in >90% of women potentially eligible for PBRT after WLE with noninvolved resection margins.

  2. Expressly fabricated molar tube bases: enhanced adhesion.

    PubMed

    Sharma, Tarun; Phull, Tarun Singh; Rana, Tarun; Kumar, Varun

    2014-06-01

    Clinicians, Orthodontists and their patients' parents often expect the best results in the shortest time span possible. Orthodontic bonding of molar tubes has been an acceptable risk in a modern era of refined biomaterials and instrumentation. Although many orthodontists still prefer banding to bonding, it is the failure rate of the tubes on molars which accounts to an impedance in molar bonding. One of the reasons for molar attachment failures is attributed to improper adaptation of the buccal tube base with or without increased thickness of composite. Merits of banding the second molars especially when these are the terminal teeth for anchorage have been overemphasized in the literature. The present article presents a simple and relatively less time consuming technique of preparing molar tubes to be bonded on tooth surfaces which may be quite difficult to isolate especially for bonding, for example, mandibular second molars. The increased surface area of the composite scaffold helps not only in enhanced bond strength but also serves to reduce the incidence of plaque accumulation given the dexterity of invitro preparation. The removal of the occlusal part of the molar tube scaffold helps in prevention of open / raised bite tendencies. The present innovation, therefore, is not merely serendipity but a structured technique to overcome a common dilemma for the clinical orthodontist. The present dictum of banding being superior to molar tube bonding may prove to be futile with trendsetting molar attachments. It is also an established fact that bonding proves to be a lesser expensive modality when compared to banding procedures. PMID:25121070

  3. Evaluation of caries in deciduous second molar and adjacent permanent molar in mixed dentition

    PubMed Central

    Srinivasan, Daya; Louis, C. Joe

    2015-01-01

    Aim: This study was done to evaluate association of caries in deciduous second molar and adjacent permanent first molar, tooth surface more involved in permanent first molar and to assess the parental awareness regarding the eruption of permanent first molar. Subjects and Methods: Three hundred and ten children (160 boys, 150 girls) of mixed dentition aged between 6 and 11 years were included. Presence or absence of paired association of caries in primary second molar and adjacent permanent first molar, of both the jaws, were noted. Parental awareness regarding the child's dentition was asked by pointing the maxillary and mandibular permanent first molar. Results: Pearson Chi-square test was used. Significance was noted in both sexes between paired nonassociation of caries in mandibular primary second molar and mandibular permanent molar (P =0.01) and paired nonassociation of caries in primary maxillary second molar and maxillary permanent first molar in girls only (P =0.04). Parental awareness that permanent first molar has erupted was 24.83% and not to be exfoliated and replaced was 22.9% for both the sexes. In permanent teeth of both the sexes, the occlusal surface was more involved with caries in maxillary teeth; the buccal surface was more involved in mandibular teeth. About 10% of the sample did not have caries in both maxillary and mandibular permanent first molar. Conclusions: Paired association of caries of primary second molar and permanent first molar though found in large number of cases was not significant. It is clear that parental awareness is less regarding the child's oral health. Thus, community-based awareness program has to be conducted to emphasize on pediatric oral health status and care. PMID:26538920

  4. Improving Dynamic Susceptibility Contrast MRI Measurement of Quantitative Cerebral Blood Flow using Corrections for Partial Volume and Nonlinear Contrast Relaxivity: a Xenon CT Comparative Study

    PubMed Central

    Zaharchuk, Greg; Bammer, Roland; Straka, Matus; Newbould, Rexford D; Rosenberg, Jarrett; Olivot, Jean-Marc; Mlynash, Michael; Lansberg, Maarten G; Schwartz, Neil E; Marks, Michael M; Albers, Gregory W; Moseley, Michael E

    2010-01-01

    Purpose To test whether dynamic susceptibility contrast MRI-based CBF measurements are improved with arterial input function (AIF) partial volume (PV) and nonlinear contrast relaxivity correction, using a gold-standard CBF method, xenon computed tomography (xeCT). Materials and Methods 18 patients with cerebrovascular disease underwent xeCT and MRI within 36 hrs. PV was measured as the ratio of the area under the AIF and the venous output function (VOF) concentration curves. A correction was applied to account for the nonlinear relaxivity of bulk blood (BB). Mean CBF was measured with both techniques and regression analyses both within and between patients were performed. Results Mean xeCT CBF was 43.313.7 ml/100g/min (meanSD). BB correction decreased CBF by a factor of 4.70.4, but did not affect precision. The least-biased CBF measurement was with BB but without PV correction (45.817.2 ml/100 g/min, coefficient of variation [COV]=32%). Precision improved with PV correction, although absolute CBF was mildly underestimated (34.310.8 ml/100 g/min, COV=27%). Between patients correlation was moderate even with both corrections (R=0.53). Conclusion Corrections for AIF PV and nonlinear BB relaxivity improve bolus MRI-based CBF maps. However, there remain challenges given the moderate between-patient correlation, which limit diagnostic confidence of such measurements in individual patients. PMID:19787719

  5. Integration of 3D scale-based pseudo-enhancement correction and partial volume image segmentation for improving electronic colon cleansing in CT colonograpy.

    PubMed

    Zhang, Hao; Li, Lihong; Zhu, Hongbin; Han, Hao; Song, Bowen; Liang, Zhengrong

    2014-01-01

    Orally administered tagging agents are usually used in CT colonography (CTC) to differentiate residual bowel content from native colonic structures. However, the high-density contrast agents tend to introduce pseudo-enhancement (PE) effect on neighboring soft tissues and elevate their observed CT attenuation value toward that of the tagged materials (TMs), which may result in an excessive electronic colon cleansing (ECC) since the pseudo-enhanced soft tissues are incorrectly identified as TMs. To address this issue, we integrated a 3D scale-based PE correction into our previous ECC pipeline based on the maximum a posteriori expectation-maximization partial volume (PV) segmentation. The newly proposed ECC scheme takes into account both the PE and PV effects that commonly appear in CTC images. We evaluated the new scheme on 40 patient CTC scans, both qualitatively through display of segmentation results, and quantitatively through radiologists' blind scoring (human observer) and computer-aided detection (CAD) of colon polyps (computer observer). Performance of the presented algorithm has shown consistent improvements over our previous ECC pipeline, especially for the detection of small polyps submerged in the contrast agents. The CAD results of polyp detection showed that 4 more submerged polyps were detected for our new ECC scheme over the previous one. PMID:24699352

  6. Oscillatory Zoning in Plagioclase: Effect of P, T And Partial Molal Volumes of Na2O And CaO In The Melt

    NASA Astrophysics Data System (ADS)

    Kilinc, A.; Ustunisik, G.

    2009-05-01

    In many explosively erupting volcanoes geophysical evidence suggests pooling of magma in multiple magma chambers within the crust before eruption. We evaluated the effect of adiabatic uprise of magma followed by isobaric crystallization on plagioclase zoning using the Melts software. A basaltic andesite, parental magma for the explosively erupting Erciyes Volcano in central Turkey, has been used as the starting composition in the calculations. In our multiple magma chamber model, basaltic andesite magma moves adiabatically from 2 kb to a shallower magma chamber at 1.5 kb pressure where it crystallizes isobarically and then moves adiabatically again from 1.5 kb to a magma chamber at 1 kb where it crystallizes isobarically before erupting. In our simulations, the An content of plagioclase increases in the adiabatic uprise steps and decreases in the isobaric steps. The net result of this calculation shows that oscillatory zoning is developed. Increase and decrease in the An content of plagioclase during adiabatic and isobaric steps, respectively is explained by the effect of pressure on the partial molal volumes of Na2O and CaO in the melt.

  7. Revolution vs status quo? Non-intervention strategy of asymptomatic third molars causes harm.

    PubMed

    Toedtling, V; Yates, J M

    2015-07-10

    The Faculty of Dental Surgery of the Royal College of Surgeons of England has prompted the National Institute for Health and Care Excellence to urgently re-assess the TA1 guidance on extractions of wisdom teeth and highlighted required amendments to the present version in light of published evidence concerning the harm caused by wisdom tooth retention. This article seeks to address the recent concerns relating the increasing frequency of distal-cervical caries in lower second molar teeth when associated with asymptomatic partially erupted mesial or horizontal impacted mandibular third molars. Such acute angle impactions are classified as partially erupted when one of the third molar cusps breached the epithelial attachment of the distal aspect of the second molar, thus prevents the formation of a gingival seal. At its earliest stage the wisdom tooth appears clinically absent or unerupted, yet histologically the architecture of the gingival epithelium has been disrupted allowing ingress of microbes, demineralisation and succeeding cavitation to take place on the distal aspect of the second molar. We hope to highlight the difficulties faced in addressing this growing clinical problem and encourage clinicians to re-evaluate their own caries risk assessment and caries prevention strategy in relation to mesial and horizontal third molar extractions. PMID:26159975

  8. Antibiotics in third molar surgery.

    PubMed

    Vlcek, Daniel; Razavi, Amir; Kuttenberger, Johannes J

    2014-01-01

    The aim of this survey was to assess the knowledge and practice of Swiss dentists focusing on the use of antibiotics in prophylactic surgical removal of lower wisdom teeth. A postal survey was conducted among all 3288 dentists who are members of the Swiss Dental Society (SSO) representing nearly all dentists in Switzerland. The questionnaire consisted of 13 questions with mostly multiple-choice answers. Demographic profile, surgical experience, the use of antibiotics, and wound management, i.e. wound closure and the use of mouth rinse were assessed. A response rate of 55% was obtained. Most Swiss dentists perform surgical extractions in their practices. Of all dentists, 18.6% used antibiotics routinely, but a large variation was found comparing the three linguistic regions of Switzerland with the highest prescription rate of 48% in the French-speaking south-west of Switzerland. Fifty-two percent of dentists prescribed amoxicillin in a dose of 750 mg. Most often three daily doses were prescribed (47%). A postoperative regime was prescribed by 54.4% of dentists. French language (p=0.003), graduation from the university of Geneva (p=0.007), foreign diplomas (p<0.001), and dentists with diplomas awarded from 2001-2006 (p=0.004) showed a highly significant correlation with the use of antibiotics. In Switzerland, prophylactic antibiotics are used in third molar surgery. Antibiotic prescription however largely depends on geographical situation and dentist profiles. The assessment of antibiotic use in private practices is important in the light of growing evidence that antibiotic overuse may lead to development of multiresistant bacterial strains. In a second part results regarding wound management and mouth rinse will be presented. PMID:24671748

  9. Unilateral Molar Distalization: A Nonextraction Therapy

    PubMed Central

    Prasad, M. Bhanu; Sreevalli, S.

    2012-01-01

    In the recent years, nonextraction treatment approaches and noncompliance therapies have become more popular in the correction of space discrepancies. One of the conventional approaches for space gaining in the arches without patient compliance is done by using certain extra oral appliances or intraoral appliance. The greatest advantage of certain appliances like fixed functional and molar distalization appliances is that they minimize the dependence on patient cooperation. Molar distalization appliances like pendulum appliance which distalizes the molar rapidly without the need of head gear can be used in patients as a unilateral space gaining procedure due to buccal segment crowding. PMID:23320203

  10. Role of third molars in orthodontics

    PubMed Central

    Almpani, Konstantinia; Kolokitha, Olga-Elpis

    2015-01-01

    The role of third molars in the oral cavity has been extensively studied over the years. Literature includes numerous diagnostic and treatment alternatives regarding the third molars. However, an issue that has not been discussed at the same level is their involvement in orthodontic therapy. The aim of this study is to present a review of the contemporary literature regarding the most broadly discussed aspects of the multifactorial role of third molars in orthodontics and which are of general dental interest too. PMID:25685759

  11. Improved longitudinal [(18)F]-AV45 amyloid PET by white matter reference and VOI-based partial volume effect correction.

    PubMed

    Brendel, Matthias; Hgenauer, Marcus; Delker, Andreas; Sauerbeck, Julia; Bartenstein, Peter; Seibyl, John; Rominger, Axel

    2015-03-01

    Amyloid positron-emission-tomography (PET) offers an important research and diagnostic tool for investigating Alzheimer's disease (AD). The majority of amyloid PET studies have used the cerebellum as a reference region, and clinical studies have not accounted for atrophy-based partial volume effects (PVE). Longitudinal studies using cerebellum as reference tissue have revealed only small mean increases and high inter-subject variability in amyloid binding. We aimed to test the effects of different reference regions and PVE-correction (PVEC) on the discriminatory power and longitudinal performance of amyloid PET. We analyzed [(18)F]-AV45 PET and T1-weighted MRI data of 962 subjects at baseline and two-year follow-up data of 258 subjects. Cortical composite volume-of-interest (VOI) values (COMP) for tracer uptake were generated using either full brain atlas VOIs, gray matter segmented VOIs or gray matter segmented VOIs after VOI-based PVEC. Standard-uptake-value ratios (SUVR) were calculated by scaling the COMP values to uptake in cerebellum (SUVRCBL), brainstem (SUVRBST) or white matter (SUVRWM). Mean SUV, SUVR, and changes after PVEC were compared at baseline between diagnostic groups of healthy controls (HC; N=316), mild cognitive impairment (MCI; N=483) and AD (N=163). Receiver operating characteristics (ROC) were calculated for the discriminations between HC, MCI and AD, and expressed as area under the curve (AUC). Finally, the longitudinal [(18)F]-AV45-PET data were used to analyze the impact of quantitation procedures on apparent changes in amyloid load over time. Reference region SUV was most constant between diagnosis groups for the white matter. PVEC led to decreases of COMP-SUV in HC (-18%) and MCI (-10%), but increases in AD (+7%). Highest AUCs were found when using PVEC with white matter scaling for the contrast between HC/AD (0.907) or with brainstem scaling for the contrast between HC/MCI (0.658). Longitudinal increases were greatest in all diagnosis groups with application of PVEC, and inter-subject variability was lowest for the white matter reference. Thus, discriminatory power of [(18)F]-AV45-PET was improved by use of a VOI-based PVEC and white matter or brainstem rather than cerebellum reference region. Detection of longitudinal amyloid increases was optimized with PVEC and white matter reference tissue. PMID:25482269

  12. Partial filling affinity capillary electrophoresis using large-volume sample stacking with an electroosmotic flow pump for sensitive profiling of glycoprotein-derived oligosaccharides.

    PubMed

    Fukushima, Eriko; Yagi, Yuki; Yamamoto, Sachio; Nakatani, Yumi; Kakehi, Kazuaki; Hayakawa, Takao; Suzuki, Shigeo

    2012-07-13

    An online preconcentration technique, large-volume sample stacking with an electroosmotic flow pump (LVSEP) was combined with partial filling affinity capillary electrophoresis (PFACE) to realize highly sensitive analysis of the interaction of glycoprotein-derived oligosaccharides with some plant lectins. Oligosaccharides derivatized with 8-aminopyrene-1,3,6-trisulfonic acid (APTS) were delivered to an entire neutrally-coated capillary and then lectin solution was hydrodynamically introduced from the outlet of the capillary as a short plug. A negative voltage was then applied after immersion of both ends of the capillary in 100 mM Tris-acetate buffer, pH 7.0 containing 0.5% hydroxypropylcellulose as electrophoresis buffers. A low concentration of electrolytes in the sample solution causes a significant flow by electroendosmosis from anode to cathode and the APTS-labeled oligosaccharides move quickly towards the anode and concentrate in the lectin phase. Finally, electroosmotic flow becomes negligible when the capillary is filled with the background electrolyte delivered from the anodic reservoir and APTS-labeled saccharides pass through the lectin plug and are detected at the anodic end. If the APTS-labeled oligosaccharides are recognized by the lectin, the migration profiles should be altered. The sensitivity was enhanced by a factor of ca. 900 compared to typical hydrodynamic injection (3.45 kPa, 10s). By this method, increased residence time of APTS-saccharides in the lectin plug indicates highly efficient interaction with lectins, which differs completely from the results obtained by ordinary lectin PFACE. The run-to-run repeatability (n=18) of the migration time and peak area was high, with relative standard deviations of less than 0.7% and 6.1%, respectively. PMID:22410158

  13. Maxillary second molar extractions in orthodontic treatment.

    PubMed

    Lee, Wilson; Wong, Ricky Wing-Kit; Ikegami, Tomio; Hgg, Urban

    2008-01-01

    This article is a review of the rationales, indications, methods, and effects of orthodontic treatment with maxillary second molar extractions. In addition to the patient's malocclusion, specific considerations about the status and position of the maxillary second and third molars should be taken into account. In recent years, the development of temporary anchorage devices, in addition to extraoral traction and intraoral distalization appliances, has become another armamentarium in the distalization of the maxillary posterior teeth, which may affect the selection of teeth to be extracted from second to third molars. In conclusion, extraction of maxillary second molars is a viable option in selected cases at present, but it is important to understand the indications and limitations of this treatment choice. PMID:18426106

  14. Maxillary molar distalization with first class appliance.

    PubMed

    Ramesh, Namitha; Palukunnu, Biswas; Ravindran, Nidhi; Nair, Preeti P

    2014-01-01

    Non-extraction treatment has gained popularity for corrections of mild-to-moderate class II malocclusion over the past few decades. The distalization of maxillary molars is of significant value for treatment of cases with minimal arch discrepancy and mild class II molar relation associated with a normal mandibular arch and acceptable profile. This paper describes our experience with a 16-year-old female patient who reported with irregularly placed upper front teeth and unpleasant smile. The patient was diagnosed to have angles class II malocclusion with moderate maxillary anterior crowding, deep bite of 4 mm on a skeletal class II base with an orthognathic maxilla and retrognathic mandible and normal growth pattern. She presented an ideal profile and so molar distalization was planned with the first-class appliance. Molars were distalised by 8 mm on the right and left quadrants and class I molar relation achieved within 4 months. The space gained was utilised effectively to align the arch and establish a class I molar and canine relation. PMID:24577171

  15. LANDSAT-D data format control book. Volume 6, appendix C: Partially processed multispectral scanner high density tape (HDT-AM)

    NASA Technical Reports Server (NTRS)

    Andersen, K. E.

    1982-01-01

    The format of high density tapes which contain partially processed LANDSAT 4 and LANDSAT D prime MSS image data is defined. This format is based on and is compatible with the existing format for partially processed LANDSAT 3 MSS image data HDTs.

  16. Dependence of the volume characteristics and viscosity of solutions of methanol-octane-naphthalene on composition at 25C

    NASA Astrophysics Data System (ADS)

    Dyshin, A. A.; Eliseeva, O. V.; Kiselev, M. G.

    2014-10-01

    The limiting solubility of naphthalene in a mixture of methanol-octane at 25C is determined via isothermal saturation. The kinematic viscosity of a mixture of methanol-octane-naphthalene is measured at 25C. Data on the density of triple mixtures of methanol-octane-naphthalene, used to calculate the partial and apparent molar volumes of naphthalene, are obtained with a high degree of accuracy. The obtained results are discussed in terms of the interactions that occur in solution.

  17. Caries Management Strategies for Primary Molars

    PubMed Central

    Santamaria, R.M.; Innes, N.P.T.; Machiulskiene, V.; Evans, D.J.P.; Splieth, C.H.

    2014-01-01

    Minimal invasive approaches to managing caries, such as partial caries removal techniques, are showing increasing evidence of improved outcomes over the conventional complete caries removal. There is also increasing interest in techniques where no caries is removed. We present the 1-yr results of clinical efficacy for 3 caries management options for occlusoproximal cavitated lesions in primary molars: conventional restorations (CR; complete caries removal and compomer restoration), Hall technique (HT; no caries removal, sealing in with stainless steel crowns), and nonrestorative caries treatment (NRCT; no caries removal, opening up the cavity, teaching brushing and fluoride application). In sum, 169 children (3-8 yr old; mean, 5.56 ± 1.45 yr) were enrolled in this secondary care–based, 3-arm, parallel-group, randomized clinical trial. Treatments were carried out by specialist pediatric dentists or postgraduate trainees. One lesion per child received CR, HT, or NRCT. Outcome measures were clinical failure rates, grouped as minor failure (restoration loss/need for replacement, reversible pulpitis, caries progression, etc.) and major failure (irreversible pulpitis, abscess, etc.). There were 148 children (87.6%) with a minimum follow-up of 11 mo (mean, 12.23 ± 0.98 mo). Twenty teeth were recorded as having at least 1 minor failure: NRCT, n = 8 (5%); CR, n = 11 (7%); HT, n = 1 (1%) (p = .002, 95% CI = 0.001 to 0.003). Only the comparison between NRCT and CR showed no significant difference (p = .79, 95% CI = 0.78 to 0.80). Nine (6%) experienced at least 1 major failure: NRCT, n = 4 (2%); CR, n = 5 (3%); HT, n = 0 (0%) (p = .002, 95% CI = 0.001 to 0.003). Individual comparison of NRCT and CR showed no statistically significant difference in major failures (p = .75, 95% CI = 0.73 to 0.76). Success and failure rates were not significantly affected by pediatric dentists’ level of experience (p = .13, 95% CI = 0.12 to 0.14). The HT was significantly more successful clinically than NRCT and CR after 1 yr, while pairwise analyses showed comparable results for treatment success between NRCT and CR (ClinicalTrials.gov NCT01797458). PMID:25216660

  18. SU-E-J-76: Incorporation of Ultrasound Elastography in Target Volume Delineation for Partial Breast Radiotherapy Planning: A Comparative Study

    SciTech Connect

    Juneja, P; Harris, E; Bamber, J

    2014-06-01

    Purpose: There is substantial observer variability in the delineation of target volumes for post-surgical partial breast radiotherapy because the tumour bed has poor x-ray contrast. This variability may result in substantial variations in planned dose distribution. Ultrasound elastography (USE) has an ability to detect mechanical discontinuities and therefore, the potential to image the scar and distortion in breast tissue architecture. The goal of this study was to compare USE techniques: strain elastography (SE), shear wave elastography (SWE) and acoustic radiation force impulse (ARFI) imaging using phantoms that simulate features of the tumour bed, for the purpose of incorporating USE in breast radiotherapy planning. Methods: Three gelatine-based phantoms (10% w/v) containing: a stiff inclusion (gelatine 16% w/v) with adhered boundaries, a stiff inclusion (gelatine 16% w/v) with mobile boundaries and fluid cavity inclusion (to mimic seroma), were constructed and used to investigate the USE techniques. The accuracy of the elastography techniques was quantified by comparing the imaged inclusion with the modelled ground-truth using the Dice similarity coefficient (DSC). For two regions of interest (ROI), the DSC measures their spatial overlap. Ground-truth ROIs were modelled using geometrical measurements from B-mode images. Results: The phantoms simulating stiff scar tissue with adhered and mobile boundaries and seroma were successfully developed and imaged using SE and SWE. The edges of the stiff inclusions were more clearly visible in SE than in SWE. Subsequently, for all these phantoms the measured DSCs were found to be higher for SE (DSCs: 0.910.97) than SWE (DSCs: 0.680.79) with an average relative difference of 23%. In the case of seroma phantom, DSC values for SE and SWE were similar. Conclusion: This study presents a first attempt to identify the most suitable elastography technique for use in breast radiotherapy planning. Further analysis will include comparison of ARFI with SE and SWE. This work is supported by the EPSRC Platform Grant, reference number EP/H046526/1.

  19. SU-E-T-487: Impact of Geometric Uncertainties in Accelerated Partial Breast Irradiation Using the Strut-Adjusted Volume Implant (SAVI)

    SciTech Connect

    Akino, Y; Slessinger, E; Das, I; Srivastava, S

    2014-06-01

    Purpose: Single-entry multi-catheter devices have been developed for accelerated partial breast irradiation (APBI). Rotational and translational uncertainties are usually mitigated by quality assurance, however its actual dosimetric impact has not been addressed, which is presented here for SAVI applicator. Methods: Under Institutional Review Board exemption status, we retrospectively analyzed 48 APBI treatment plans using SAVI applicator. For quick calculation of dose-volume histogram (DVH) considering geometric uncertainties, the coordinate of each voxel of critical organs after rotation or translation along the central catheter was calculated using an in-house software instead of rotating or translating the entire dose distribution. Results: For most cases, the skin doses increased with rotation to both directions. At 10 degree of rotation, the increase of Dmax (percent prescribed dose) at 50% (median), 75%, 90%, and 100% (maximum) percentile were 0.3%, 1.7%, 5.6% and 25.0%, respectively. The increase of chest wall Dmax at 50%, 75%, 90%, and 100% percentile were 0.1%, 1.0%, 10.3% and 38.8%, respectively. The increase of skin Dmax of the patients with the distance between skin surface and lumpectomy cavity surface ≤16 mm was significantly larger than those with the distance >16 mm. Similarly, patients with the distance between lung and lumpectomy cavity surface ≤20 mm showed higher sensitivity of chest wall Dmax against rotation than patients with the distance <20 mm. Translation of the applicator showed larger impact on the skin dose than rotation, although the effects on chest wall was less than 2% even at 10 mm displacement. At 5 mm of translation, increase of skin Dmax at 50%, 75%, 90%, and 100% percentile were 2.3%, 8.0%, 15.3% and 77.7%, respectively. Conclusion: The impacts of the geometric uncertainties (rotation and translation) of SAVI applicator were investigated. The skin-lumpectomy cavity and lung-lumpectomy cavity distances showed significant relationship with skin and chest wall doses, respectively.

  20. Influence of the partial volume correction method on 18F-fluorodeoxyglucose brain kinetic modelling from dynamic PET images reconstructed with resolution model based OSEM

    NASA Astrophysics Data System (ADS)

    Bowen, Spencer L.; Byars, Larry G.; Michel, Christian J.; Chonde, Daniel B.; Catana, Ciprian

    2013-10-01

    Kinetic parameters estimated from dynamic 18F-fluorodeoxyglucose (18F-FDG) PET acquisitions have been used frequently to assess brain function in humans. Neglecting partial volume correction (PVC) for a dynamic series has been shown to produce significant bias in model estimates. Accurate PVC requires a space-variant model describing the reconstructed image spatial point spread function (PSF) that accounts for resolution limitations, including non-uniformities across the field of view due to the parallax effect. For ordered subsets expectation maximization (OSEM), image resolution convergence is local and influenced significantly by the number of iterations, the count density, and background-to-target ratio. As both count density and background-to-target values for a brain structure can change during a dynamic scan, the local image resolution may also concurrently vary. When PVC is applied post-reconstruction the kinetic parameter estimates may be biased when neglecting the frame-dependent resolution. We explored the influence of the PVC method and implementation on kinetic parameters estimated by fitting 18F-FDG dynamic data acquired on a dedicated brain PET scanner and reconstructed with and without PSF modelling in the OSEM algorithm. The performance of several PVC algorithms was quantified with a phantom experiment, an anthropomorphic Monte Carlo simulation, and a patient scan. Using the last frame reconstructed image only for regional spread function (RSF) generation, as opposed to computing RSFs for each frame independently, and applying perturbation geometric transfer matrix PVC with PSF based OSEM produced the lowest magnitude bias kinetic parameter estimates in most instances, although at the cost of increased noise compared to the PVC methods utilizing conventional OSEM. Use of the last frame RSFs for PVC with no PSF modelling in the OSEM algorithm produced the lowest bias in cerebral metabolic rate of glucose estimates, although by less than 5% in most cases compared to the other PVC methods. The results indicate that the PVC implementation and choice of PSF modelling in the reconstruction can significantly impact model parameters.

  1. Eruption Stage of Permanent Molars and Occlusal Caries Activity/Arrest

    PubMed Central

    Alves, L.S.; Zenkner, J.E.A.; Wagner, M.B.; Dam-Teixeira, N.; Susin, C.; Maltz, M.

    2014-01-01

    This study assessed the association between the eruption stage of permanent second molars and occlusal caries activity among 12-year-old schoolchildren from South Brazil. A cross-sectional study was performed in Porto Alegre using a multistage probability sampling strategy to select a representative sample. Clinical examination was conducted to assess the eruption stage of permanent molars, Gingival Bleeding Index, and, after tooth cleaning and drying, caries experience (noncavitated and cavitated lesions, including caries activity assessment). Data were collected on sex, socioeconomic status, mothers education, brushing frequency, and consumption of soft drinks. Generalized estimating equations were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Overall, 983 schoolchildren with 3,071 second molars were available for analysis. Whereas active caries was observed in 6.6% of fully erupted permanent second molars, caries affected 26.2%, 29.6%, and 18.2% of erupting molars classified as stages 1, 2, and 3, respectively: stage 1, partially erupted occlusal surface; stage 2, fully erupted occlusal surface, <1/2 crown exposed; and stage 3, fully erupted occlusal surface, >1/2 crown exposed. After adjusting for socioeconomic and behavioral variables, partially erupted molars were significantly more likely to present active caries lesions than molars in full occlusion: stage 1, OR = 4.99 (95% CI = 3.38, 7.38); stage 2, OR = 5.18 (95% CI = 3.14, 8.53); stage 3, OR = 3.20 (95% CI = 2.21, 4.64). Similar results were found when clinical variables were included in the adjusted model. In conclusion, most occlusal caries lesions tend to arrest/revert when teeth reach the occlusal plan; however, an important proportion of these lesions remains active and in need of proper management. Children at risk should be targeted with preventive and minimally invasive strategies. PMID:24874701

  2. Sonographic appearance of early complete molar pregnancies.

    PubMed

    Lazarus, E; Hulka, C; Siewert, B; Levine, D

    1999-09-01

    Since our anecdotal experience indicates that the classically described "snowstorm" appearance on ultrasonography of early molar pregnancies is often not present and that theca-lutein cysts are also rare, we examined the ultrasonographic appearance of early complete molar pregnancies. We reviewed the ultrasonographic reports and clinical data of 21 cases of histologically diagnosed complete molar pregnancies with a mean gestational age at sonography of 10.5 weeks (range, 4 to 18 weeks). The diagnosis of molar pregnancy was made on ultrasonography in 12 (57%) cases, was second in the differential diagnosis of one (4.8%) case, and was not considered in eight (38%) cases. No theca-lutein cysts were identified. Five of five (100%) molar pregnancies of 13 weeks or over were diagnosed prospectively, while only eight of 16 (50%) earlier pregnancies were correctly diagnosed prospectively. In a retrospective review of the available images of 16 patients, only nine of 16 (56%) images demonstrated the classic appearance, and no theca-lutein cysts were seen. We conclude that the classic appearance of complete moles on ultrasonography is seen in less than two thirds of cases and even less commonly in the first trimester. The prevalence of theca-lutein cysts is very low. PMID:10478967

  3. Molar heat capacity and molar excess enthalpy measurements in aqueous amine solutions

    NASA Astrophysics Data System (ADS)

    Poozesh, Saeed

    Experimental measurements of molar heat capacity and molar excess enthalpy for 1, 4-dimethyl piperazine (1, 4-DMPZ), 1-(2-hydroxyethyl) piperazine (1, 2-HEPZ), I-methyl piperazine (1-MPZ), 3-morpholinopropyl amine (3-MOPA), and 4-(2-hydroxy ethyl) morpholine (4, 2-HEMO) aqueous solutions were carried out in a C80 heat flow calorimeter over a range of temperatures from (298.15 to 353.15) K and for the entire range of the mole fractions. The estimated uncertainty in the measured values of the molar heat capacity and molar excess enthalpy was found to be +/- 2%. Among the five amines studied, 3-MOPA had the highest values of the molar heat capacity and 1-MPZ the lowest. Values of molar heat capacities of amines were dominated by --CH 2, --N, --OH, --O, --NH2 groups and increased with increasing temperature, and contributions of --NH and --CH 3 groups decreased with increasing temperature for these cyclic amines. Molar excess heat capacities were calculated from the measured molar heat capacities and were correlated as a function of the mole fractions employing the Redlich-Kister equation. The molar excess enthalpy values were also correlated as a function of the mole fractions employing the Redlich-Kister equation. Molar enthalpies at infinite dilution were derived. Molar excess enthalpy values were modeled using the solution theory models: NRTL (Non Random Two Liquid) and UNIQUAC (UNIversal QUAsi Chemical) and the modified UNIFAC (UNIversal quasi chemical Functional group Activity Coefficients - Dortmund). The modified UNIFAC was found to be the most accurate and reliable model for the representation and prediction of the molar excess enthalpy values. Among the five amines, the 1-MPZ + water system exhibited the highest values of molar excess enthalpy on the negative side. This study confirmed the conclusion made by Maham et al. (71) that -CH3 group contributed to higher molar excess enthalpies. The negative excess enthalpies were reduced due to the contribution of --O and --OH groups in 3-MOPA; 1, 2-HEPZ and 4, 2-HEMO. Conclusions made by Maham et al. (71 ) stating that the interaction between water (--OH group) and diethylamine (--NH group) was more dominant than the interactions between --OH groups from water and alcohol molecules were supported by this study for cyclic amines.

  4. Population systematics of chimpanzees using molar morphometrics.

    PubMed

    Pilbrow, Varsha

    2006-12-01

    When dental morphological variation within extant species is used as a guideline to partition variation within fossil samples into species, the underlying assumption is that fossil species are equivalent to extant species. This is the case despite the fact that dental morphology, which is commonly used to differentiate fossil species, is rarely used to differentiate extant species. Aspects of external morphology, ecology, behavior, breeding patterns, and molecular structure that are used to delineate living species are generally not available for fossils. In this paper, the utility of dental evidence for sorting fossil samples into species is evaluated by testing whether molar occlusal morphology is capable of sorting populations of Pan into the species and subspecies already well-established by nondental evidence. The dentitions of 341 chimpanzee individuals, sampled from regions throughout equatorial Africa, were sorted into 16 populations using rivers to demarcate the boundaries between populations. Digital-imaging software was used to measure 15 traits on the occlusal surface of each upper molar and 19 on each lower molar. After applying size adjustments, size-transformed and untransformed variables were subjected to discriminant analysis, with separate analyses carried out for each molar type. Results indicate that populations of Pan troglodytes and Pan paniscus are well differentiated at all molar positions. Populations of P. t. verus are distinct from other populations of P. troglodytes. Populations of P. t. troglodytes and P. t. schweinfurthii show close dental similarity. A distinct population is recognized at the Nigeria-Cameroon border, indicating the presence of P. t. vellerosus. The concordance between the patterns of diversity recognized by this study and other molecular and nonmolecular studies indicates that paleontological species that are similar to species of Pan in terms of size and patterns of diversification may be differentiated using molar morphology. PMID:16965803

  5. The relationship of maternal age to molar pregnancy incidence, risks for chemotherapy and subsequent pregnancy outcome.

    PubMed

    Savage, P M; Sita-Lumsden, A; Dickson, S; Iyer, R; Everard, J; Coleman, R; Fisher, R A; Short, D; Casalboni, S; Catalano, K; Seckl, M J

    2013-05-01

    The national registration and treatment service for molar pregnancies in the UK allows for the collection of accurate data on this relatively rare diagnosis. In England and Wales, between 2000 and 2009, 5,793 patients with complete moles and 7,790 with partial moles were registered, compared with a total of 8,242,511 conceptions. The overall molar pregnancy incidence was 1 for every 607 conceptions (complete mole 1:1,423; partial mole 1:1,058), but with major variations with age. For complete moles, the risk varied from < 1:1,000 for ages 18-40, to 1:156 for women aged 45 and 1:8 for those aged 50 and above. The overall risk of requiring chemotherapy after a complete mole was 13.6% and 1.1% for partial mole, while the risk of a further molar pregnancy in the next conception was 1:68 but each of these figures have considerable variations with age. These modern statistics on molar pregnancy risks and outcomes should be of value to clinicians and their patients, while discussing this rare diagnosis. PMID:23654327

  6. Ionic volumes in solution.

    PubMed

    Marcus, Yizhak

    2006-12-01

    The volumetric properties of electrolytes in solutions indicate the interactions of the constituent ions with their environment: the solvent and other ions. The interactions with the solvent alone are manifested at infinite dilution by the standard partial molar volume, V(infinity)(salt), obtained from density measurements. To study the interactions, it is necessary to split V(infinity)(salt) into the additive ionic contributions, V(infinity)(ion), using an extra-thermodynamic assumption. Values of V(infinity)(ion) for small ions depend cardinally on the electrostriction of the solvent that can be obtained from an iterative shell-by-shell calculation from a continuum model of the solvent. The solvent shrinkage per mol of ions is DeltaV(el)(ion)<0. Also, the molar electrostriction of the solvent S, DeltaV(el)(S)<0, is calculable. The ratio DeltaV(el)(ion)/DeltaV(el)(S)=n(infinity) is the solvation number of the ion in S at infinite dilution. The calculated V(infinity)(ion)(calc) are compared with the experimental values, showing good agreement for many univalent ions in both single solvents and in some binary solvent mixtures, where no appreciable preferential solvation takes place. Ion pairing sets in under certain circumstances of ionic charge and solvent permittivity. The difference DeltaV(ip)=V(ip)(infinity)-[V(infinity)(+)+V(infinity)(-)]>0 is obtained experimentally from the pressure derivative of the association constant. The ratio Deltan(ip)=DeltaV(ip)/DeltaV(el)(S) represents the number of solvent molecules released to the bulk on ion pairing by the diminution of the electrostriction. PMID:16793195

  7. Selective alveolar corticotomy to intrude overerupted molars.

    PubMed

    Oliveira, Dauro Douglas; de Oliveira, Bruno Franco; de Arajo Brito, Helio Henrique; de Souza, Margareth Maria Gomes; Medeiros, Paulo Jos

    2008-06-01

    Orthodontic intrusion of overerupted molars in adults is challenging for most clinicians. Efficient intrusion can be achieved by combining selective alveolar corticotomies with a modified full-coverage maxillary splint to reduce surgical risks, treatment time, and costs for both orthodontists and patients. PMID:18538256

  8. Clostridium perfringens sepsis following a molar pregnancy.

    PubMed

    Adams, Brandi N; Lekovic, Jovana P; Robinson, Suzzette

    2014-01-01

    Clostridium perfringens sepsis is rare since the legalization of abortion in 1973. This is a 49 year old female who developed clostridial sepsis after suction dilation and curettage for a molar pregnancy. A hysterectomy was performed after prompt recognition, and the patient survived. PMID:24096275

  9. Root fusion in molars: incidence and sex linkage.

    PubMed

    Ross, I F; Evanchik, P A

    1981-11-01

    The study was done to determine the incidence and distribution of root fusion in 1340 maxillary and mandibular molars in 170 patients. A second objective was to determine whether root fusion of molars is sex-linked. A substantial percentage, 29% of all molars, had fused roots. Root fusion was found more frequently in maxillary than mandibular molars, 35% to 24%, and it occurred in many patients, rather than being limited to a few. Root fusion was most common in third molars, followed by second molars, in both jaws. It occurred in almost equal numbers in corresponding molars of opposite sides, approaching bilateral symmetry. The proportion of molars with root fusion was approximately 5% greater in females than in males, and about 13% more females had molar root fusion than males. PMID:6946206

  10. Radiographic findings on 3rd molars removed in 20-year-old men.

    PubMed

    Rajasuo, Ari; Peltola, Jaakko; Vent, Irja; Murtomaa, Heikki

    2003-10-01

    In this study we assess radiographic findings characteristic of mandibular 3rd molars that had required either routine or surgical extraction. X-ray findings relating to acute pericoronitis were also examined. The material was collected by investigating patient records and rotational panoramic radiographs of 20-year-old Finnish male conscripts (n = 738) treated during military service because of 3rd-molar-related problems. The follicle around the crown of mandibular 3rd molars with acute pericoronitis was enlarged in 19% of cases and in 13% of chronic symptom-free pericoronitis cases (not statistically significant difference). Mandibular 3rd molars extracted surgically were more often mesially inclined than those extracted routinely (61% vs. 23%; P < 0.001), partially or totally intrabony impacted (92% vs. 66%; P < 0.001) and deep situated (on average 4.2 mm vs. 2.5 mm under the occlusal plane). Surgical extraction was also associated with the roots completely developed [92% vs. 84% of the teeth routinely extracted, odds ratio (OR) 2.6, 95% confidence interval (CI) 1.2-5.5] and with the absence of radiographic pericoronitis [around 27% vs. 39% of the teeth routinely extracted (OR 0.5, 95% CI 0.3-0.8)]. In 86% of cases the space between 2nd molar and ramus of the mandible was narrower than the 3rd molar extracted surgically, whereas this was 62% in routine extraction cases (P < 0.001). We conclude that there are some typical 3rd-molar findings in rotational panoramic radiographs that show a need for surgical extraction. PMID:14763776

  11. Cyclosporin A-induced alterations of dentinogenesis in rat molars.

    PubMed

    Ayanoglou, C M; Godeau, G; Lesty, C; Septier, D; Goldberg, M

    1997-03-01

    Cyclosporin A (CsA), a widely used immunosuppressive drug, induces gingival overgrowth and modifications of bone remodelling. The scope of this study was to investigate the possible effect of CsA on dentin. Thirty mg/kg/day of CsA were administered orally to male Sprague-Dawley rats for nineteen weeks. The same number of control rats received oil-based vehicle solution. Rats were anesthetized, and tissues were fixed by an intracardiac perfusion of fixative solution. Mandibles were dissected, demineralized, and processed for Epon embedding. Semi-thin sections of the first molars revealed alterations at the secondary dentin-pulp interface in four out of six experimental animals. The changes consisted of the formation of: 1) osteodentin spurs, in which the volume and interface with the secondary dentin varied from about 25,000 to 75,000 microns 3 and from 1400 to 3530 microns 2, respectively; 2) abnormally shaped and irregularly spaced incremental lines; and 3) numerous globular formations embedded in dentin or free in the pulp. These results indicate that CsA induces abnormal mineralized matrix formation in dentin and in the peripheral part of the pulp in rat molars. PMID:9083937

  12. The Diagnosis of Choriocarcinoma in Molar Pregnancies: A Revised Approach in Clinical Testing

    PubMed Central

    Duffy, Lisa; Zhang, Liangtao; Sheath, Karen; Love, Donald R.; George, Alice M.

    2015-01-01

    Background Hydatidiform moles occur in approximately 1 in 1,500 pregnancies; however, early miscarriages or spontaneous abortions may not be correctly identified as molar pregnancies due to poor differentiation of chorionic villi. Methods The current clinical testing algorithm used for the detection of hydatidiform moles uses a combination of morphological analysis and p57 immunostaining followed by ploidy testing to establish a diagnosis of either a complete or partial molar pregnancy. We review here 198 referrals for fluorescence in situ hybridization (FISH) ploidy testing, where the initial diagnosis based on morphology is compared to the final diagnosis based on a combination of morphology, FISH and p57 immunohistochemical (IHC) staining. Results Approximately 40% of cases were determined to be genetically abnormal, but only 28.8% of cases were diagnosed as molar pregnancies. The underestimation of complete molar pregnancies and those with androgenetic inheritance was also found to be likely using conventional diagnostic methods, as atypical p57 staining was observed in approximately 10% of cases. Conclusions Our findings suggest that a revised approach to testing products of conception is necessary, with cases screened according to their clinical history in order to distinguish molar pregnancy referrals from hydropic pregnancies. PMID:26566410

  13. Assessment of association between molar incisor hypomineralization and hypomineralized second primary molar

    PubMed Central

    Mittal, Rakesh; Chandak, Shweta; Chandwani, Manisha; Singh, Prabhat; Pimpale, Jitesh

    2016-01-01

    Background: The term molar incisor hypomineralization (MIH) has been described as a clinical entity of systemic origin affecting the enamel of one or all first permanent molars and also the incisors; less frequently the second primary molars have also been reported to develop hypomineralization of the enamel, along with MIH. Aim: To scrutinize the association between hypomineralized second primary molars (HSPMs) and MIH and their prevalence in schoolgoing pupils in Nagpur, Maharashtra, India and the associated severity of dental caries. Design: A sample of 1,109 pupils belonging to 3–12-year-old age group was included. The entire sample was then divided into Group I (3–5 years) and Group II (6–12 years). The scoring criteria proposed by the European Academy of Pediatric Dentistry for hypomineralization was used to score HSPM and MIH. The International Caries Detection and Assessment System II (ICDAS II) was used for appraising caries status in the hypomineralized molars. The examination was conducted by a single calibrated dentist in schools in daylight. The results, thus obtained, were statistically analyzed using Chi-square test and odds ratio. Result: Of the children examined, 10 in Group I (4.88%) had HSPM and 63 in Group II (7.11%) had MIH in at least one molar. In Group II, out of 63 subjects diagnosed with MIH, 30 subjects (48%) also had HSPM. Carious lesions with high severity were appreciated in hypomineralized molars. Conclusion: The prevalence of HSPM was 4.88% and of MIH was 7.11%. Approximately half of the affected first permanent molars were associated with HSPM. The likelihood of development of caries increased with the severity of hypomineralization defect. PMID:27011930

  14. Bilateral inverted and impacted maxillary third molars: A case report

    PubMed Central

    Barakat, Ali; Al-Turkmani, Tareq; Al-Yousef, Abdulaziz

    2015-01-01

    Bilateral inverted third molar impaction is an extremely rare condition. We reported the case of a 50-year-old female patient with bilateral inverted and impacted maxillary third molars. Both were asymptomatic and pathology free clinically and radiographically. Surgical extraction of these inverted third molars with inaccessible positions requires an aggressive bone removal on the tuberosity bilaterally. Moreover, it contains a high risk of displacement of the inverted third molar into the maxillary sinus. Conservative management was the choice, with the patients agreement, and the inverted third molars were left in situ. Key words:Bilateral inverted, maxillary third molar, upper impacted tooth. PMID:26330945

  15. Root and Root Canal Morphology of Human Third Molar Teeth.

    PubMed

    Mohammadi, Zahed; Jafarzadeh, Hamid; Shalavi, Sousan; Bandi, Shilpa; Patil, Shankargouda

    2015-04-01

    Successful root canal treatment depends on having comprehensive information regarding the root(s)/canal(s) anatomy. Dentists may have some complication in treatment of third molars because the difficulty in their access, their aberrant occlusal anatomy and different patterns of eruption. The aim of this review was to review and address the number of roots and root canals in third molars, prevalence of confluent canals in third molars, C-shaped canals, dilaceration and fusion in third molars, autotransplantation of third molars and endodontic treatment strategies for third molars. PMID:26067735

  16. Human dental age estimation combining third molar(s) development and tooth morphological age predictors.

    PubMed

    Thevissen, P W; Galiti, D; Willems, G

    2012-11-01

    In the subadult age group, third molar development, as well as age-related morphological tooth information can be observed on panoramic radiographs. The aim of present study was to combine, in subadults, panoramic radiographic data based on developmental stages of third molar(s) and morphological measurements from permanent teeth, in order to evaluate its added age-predicting performances. In the age range between 15 and 23years, 25 gender-specific radiographs were collected within each age category of 1year. Third molar development was classified and registered according the 10-point staging and scoring technique proposed by Gleiser and Hunt (1955), modified by Khler (1994). The Kvaal (1995) measuring technique was applied on the indicated teeth from the individuals' left side. Linear regression models with age as response and third molar-scored stages as explanatory variables were developed, and morphological measurements from permanent teeth were added. From the models, determination coefficients (R (2)) and root-mean-square errors (RMSE) were calculated. Maximal-added age information was reported as a 6% R increase and a 0.10-year decrease of RMSE. Forensic dental age estimations on panoramic radiographic data in the subadult group (15-23year) should only be based on third molar development. PMID:22885953

  17. LETTER TO THE EDITOR: Volume-controlled buckling of thin elastic shells: application to crusts formed on evaporating partially wetted droplets

    NASA Astrophysics Data System (ADS)

    Head, D. A.

    2006-10-01

    Motivated by observing the buckling of glassy crusts formed on evaporating droplets of polymer and colloid solutions, we numerically model the deformation and buckling of spherical elastic caps controlled by varying the volume between the shell and the substrate. This volume constraint mimics the incompressibility of the unevaporated solvent. Discontinuous buckling is found to occur for sufficiently thin and/or large contact angle shells, and robustly takes the form of a single circular region near the boundary that 'snaps' to an inverted shape, in contrast to the externally pressurized shells case. Scaling theory for shallow shells is shown to approximate well the critical buckling volume, the subsequent enlargement of the inverted region and the contact line force.

  18. Relationship between molar root fusion and localized periodontitis.

    PubMed

    Hou, G L; Tsai, C C; Huang, J S

    1997-04-01

    We investigated the relationship between molar root fusion and localized periodontitis in this study. A total of 143 individuals (1,109 molars) aged 23 to 68 years were examined for the presence of molar root fusion at diseased and healthy sites. Molar root fusions were diagnosed by periapical radiographs and clinical probing. Periodontal parameters measured included probing depth (PD), clinical attachment loss (CAL), gingival index (GI), and plaque index (PLI) around fused molars. Results indicated that the prevalence of molar root fusions in males and females was 15.2% (93/612) and 32.2% (160/497), respectively. The distribution of molars with root fusions occurs in the following order: maxillary second molars (51.8%), mandibular second molars (32.3%), maxillary first molars (5.7%), and mandibular first molars (0%). Statistically significant differences were observed between molar root fusions at healthy and diseased sites with respect to PLI, GI, PD, and CAL. The highest prevalence of molar root fusion was observed in females. PMID:9150035

  19. LANDSAT-D data format control book. Volume 6, appendix A: Partially processed thematic mapper High Density Tape (HDT-AT)

    NASA Technical Reports Server (NTRS)

    Jai, A.

    1982-01-01

    One of the outputs of the data management system being developed to provide a variety of standard image products from the thematic mapper and the multispectral band scanners on LANDSAT 4, is the partially processed TM data (radiometric corrections applied and geometric correction matrices for two projections appended) which is recorded on a 28-track high density tape. Specifications are presented for the format of the recorded data as well as for the time code and the major and minor frames of the tape. Major frame types, formats, and field definitions are included.

  20. Molar tubal ectopic pregnancy: Report of two cases.

    PubMed

    Mbarki, Chaouki; Jerbi, Emna; Hsayaoui, Najeh; Zouari, Fatma; Ben Brahim, Ehsen; Oueslati, Hedhili

    2015-06-01

    Ectopic molar pregnancy is a rare occurrence and consequently not often considered as a diagnostic possibility. We report two cases of molar hydatidiform tubal pregnancy. Diagnosis of ectopic pregnancy was confirmed on clinical biological and sonographic investigations. Diagnosis of molar pregnancy was done on histopathology. The clinical course was favorable for both patients. Although rare, molar changes can occur at any site of an ectopic pregnancy. Clinical diagnosis of a molar pregnancy is difficult but histopathology is the gold standard for diagnosis. PMID:25510265

  1. Periodontal changes following molar intrusion with miniscrews

    PubMed Central

    Bayani, Shahin; Heravi, Farzin; Radvar, Mehrdad; Anbiaee, Najmeh; Madani, Azam Sadat

    2015-01-01

    Background: With the introduction of skeletal anchorage system, recently it is possible to successfully intrude molar teeth. On the other hand, there have been concerns about periodontal changes associated with intrusion and there are few studies on this topic, especially for posterior teeth. Materials and Methods: Ten female patients were enrolled in this study. Maxillary molar intrusion was achieved by inserting two miniscrews and a 17 25 titanium molybdenum alloy spring. Crestal height changes were evaluated at three intervals including: Baseline (T0), end of active treatment (T1) and 6 months after retention (T2). Other variables including probing depth, gingival recession, attachment level and bleeding on probing were evaluated by clinical measurements in the three above mentioned intervals. One-sample Kolmogrov-Smirnov test ascertained the normality of the data. For all patients, the changes in tooth position and crestal height were evaluated using one-sample t-test. (P < 0.05) Results: Supra-erupted molars were successfully intruded a mean of 2.1 0.9 mm during active treatment (T0-T1). A mean bone resorption of 0.9 0.9 mm in mesial crest and 1 0.8 mm in distal crest had occurred in total treatment (T0-T2). A mean of 0.6 1.4 mm bone was deposited on mesial crest during the retention period (T1-T2) following tooth relapse. On average, 0.8 0.4 mm attachment gain was obtained. Gingival margin coronalized a mean of 0.8 0.6 mm throughout the entire treatment. Probing depth showed no significant change during treatment. Conclusion: Within the limitations of this study, these results suggest that not only periodontal status was not negatively affected by intrusion, but also there were signs of periodontal improvement including attachment gain and shortening of clinical crown height. PMID:26288629

  2. Onset of molar incisor hypomineralization (MIH).

    PubMed

    Fagrell, Tobias G; Salmon, Phil; Melin, Lisa; Norn, Jrgen G

    2013-01-01

    The etiological factors and timing of the onset of molar incisor hypomineralization (MIH) are still not clear. The aim of this study was to examine ground radial and sagittal sections from teeth diagnosed with MIH using light microscopy, polarized light microscopy and X-ray micro-computed tomography (XMCT) and to estimate the onset and timing of the MIH and to relate the hypomineralized enamel to the incremental lines. Thirteen extracted permanent first molars diagnosed MIH, were analyzed with light microscopy and XMCT. The hypomineralized areas were mainly located in the mesio-buccal cusps, starting at the enamel-dentin-junction and continuing towards the enamel surface. In a relative gray scale analysis the values decreased from the EDJ towards the enamel surface. The findings indicate that the ameloblasts in the hypomineralized enamel are capable of forming an enamel of normal thickness, but with a substantial reduction of their capacity for maturation of enamel. Chronologically, it is estimated that the timing of the disturbance is at a period during the first 6-7 months of age. PMID:23957140

  3. Mechanics analysis of molar tooth splitting.

    PubMed

    Barani, Amir; Chai, Herzl; Lawn, Brian R; Bush, Mark B

    2015-03-01

    A model for the splitting of teeth from wedge loading of molar cusps from a round indenting object is presented. The model is developed in two parts: first, a simple 2D fracture mechanics configuration with the wedged tooth simulated by a compact tension specimen; second, a full 3D numerical analysis using extended finite element modeling (XFEM) with an embedded crack. The result is an explicit equation for splitting load in terms of indenter radius and key tooth dimensions. Fracture experiments on extracted human molars loaded axially with metal spheres are used to quantify the splitting forces and thence to validate the model. The XFEM calculations enable the complex crack propagation, initially in the enamel coat and subsequently in the interior dentin, to be followed incrementally with increasing load. The fracture evolution is shown to be stable prior to failure, so that dentin toughness, not strength, is the controlling material parameter. Critical conditions under which tooth splitting in biological and dental settings are likely to be met, however rare, are considered. PMID:25584989

  4. Preemptive analgesia in third molar impaction surgery

    PubMed Central

    Shah, Rakesh; Mahajan, Amit; Shah, Navin; Dadhania, Ashish P.

    2012-01-01

    Introduction: We have evaluated efficacy of diclofenac sodium as pre-emptive analgesia agent in a prospective triple blind placebo controlled randomized clinical trial in a patients undergoing third molar impaction surgery. Materials and Methods: Randomization of groups was done by randomization software and two groups were constituted one group receiving placebo pre operatively and then the drug for next five days while the other group was given diclofenac sodium pre operatively and then for five days. Results: Results were achieved with help of measurement of outcome variables like postoperative tenderness, swelling and trismus on a visual analogous scale (VAS) and other personalized scale. Collected data shows that there is a significant reduction in the score of postop tenderness in experimental group (P = 0.00), while there is a minimal difference between score of postoperative swelling and tenderness (P > 0.04). Conclusion: So, we can conclude that use of diclofenac sodium as a preemptive analgesic agent is beneficial for better pain control in third molar impaction surgery. PMID:23833488

  5. The molarity of molecular theory and the molecularity of molar theory.

    PubMed

    Bersh, P J

    2001-05-01

    Dinsmoor (2001) rejects shock-frequency reduction as a reinforcer for avoidance behavior, and considers this to be an invalidation of so-called molar avoidance theory. This is a narrow view of operant avoidance theory, for which shock-frequency reduction is by no means the only reinforcer. PMID:11453625

  6. Bilateral maxillary fused second and third molars: a rare occurrence.

    PubMed

    Liang, Rui-Zhen; Wu, Jin-Tao; Wu, You-Nong; Smales, Roger J; Hu, Ming; Yu, Jin-Hua; Zhang, Guang-Dong

    2012-12-01

    This case report describes the diagnosis and endodontic therapy of maxillary fused second and third molars, using cone-beam computed tomography (CBCT). A 31-year-old Chinese male, with no contributory medical or family/social history, presented with throbbing pain in the maxillary right molar area following an unsuccessful attempted tooth extraction. Clinical examination revealed what appeared initially to be a damaged large extra cusp on the buccal aspect of the distobuccal cusp of the second molar. However, CBCT revealed that a third molar was fused to the second molar. Unexpectedly, the maxillary left third molar also was fused to the second molar, and the crown of an unerupted supernumerary fourth molar was possibly also fused to the apical root region of the second molar. Operative procedures should not be attempted without adequate radiographic investigation. CBCT allowed the precise location of the root canals of the right maxillary fused molar teeth to permit successful endodontic therapy, confirmed after 6 months. PMID:23222992

  7. A simplified approach to true molar intrusion

    PubMed Central

    2012-01-01

    Background Orthodontic management of anterior open bites is a demanding task for orthodontists. Molar intrusion as a primary means of open bite correction entails the need for appropriate anchorage. Orthodontic mini implants can provide the required mechanical support. The suggested procedure aims to reduce the risk of complications such as root damage or soft tissue irritations while minimizing overall complexity. Methods Three female patients aged 14, 18 and 19 years who decided against a surgical correction were treated with a device consisting of mini implants in the palatal slope, a palatal bar and intrusion cantilevers. Results In all three patients, an open bite reduction of more than a millimeter occurred within four months. An anterior overbite of 2 mm or more could be established within 6 to 9 months. Conclusions The method presented in this article enables the practitioner to use mini implants in an easily accessible insertion site. A lab-side procedure is optional but not required. PMID:23134693

  8. Molar extinction coefficients of some fatty acids

    NASA Astrophysics Data System (ADS)

    Sandhu, G. K.; Singh, Kulwant; Lark, B. S.; Gerward, L.

    2002-10-01

    The attenuation of gamma rays in some fatty acids, viz. formic acid (CH 2O 2), acetic acid (C 2H 4O 2), propionic acid (C 3H 6O 2), butyric acid (C 4H 8O 2), n-hexanoic acid (C 6H 12O 2), n-caprylic acid (C 8H 16O 2), lauric acid (C 12H 24O 2), myristic acid (C 14H 28O 2), palmitic acid (C 16H 32O 2), oleic acid (C 18H 34O 2) and stearic acid (C 18H 36O 2), has been measured at the photon energies 81, 356, 511, 662, 1173 and 1332 keV. Experimental values for the molar extinction coefficient, the effective atomic number and the electron density have been derived and compared with theoretical calculations. There is good agreement between experiment and theory.

  9. Autotransplantation of Mandibular Third Molar: A Case Report

    PubMed Central

    Ravi kumar, Pabbati; Jyothi, Mandava; Sirisha, Kantheti; Racca, Khushboo; Uma, Chalasani

    2012-01-01

    Autogenous transplantation is a feasible, fast, and economical option for the treatment of nonsalvageable teeth when a suitable donor tooth is available. This paper presents successful autotransplantation of a mature mandibular left third molar (38) without anatomical variances is used to replace a mandibular left second molar (37). The mandibular second molar was nonrestorable due to extensive root caries and resorption of distal root. After extraction of mandibular second and third molars, root canal therapy was done for the third molar extraorally, and the tooth was reimplanted into the extracted socket of second molar site. After one year, clinical and radiographic examination revealed satisfactory outcome with no signs or symptoms suggestive of pathology. In selected cases, autogenous tooth transplantation, even after complete root formation of the donor tooth, may be considered as a practical treatment alternative to conventional prosthetic rehabilitation or implant treatment. PMID:23346422

  10. Measurement and Modeling of Resistivity as a Microscale Tool to Quantify the Volume Fraction of Lenticular (alpha)' Particles in a Partially Transformed (delta)-phase Pu-Ga Matrix

    SciTech Connect

    Haslam, J J; Wall, M A; Johnson, D L; Mayhall, D J; Schwartz, A J

    2005-07-13

    We have measured and modeled the change in electrical resistivity due to partial transformation to the martensitic {alpha}{prime}-phase in a {delta}-phase Pu-Ga matrix. The primary objective is to relate the change in resistance, measured with a 4-probe technique during the transformation, to the volume fraction of the {alpha}{prime} phase created in the microstructure. Analysis by finite element methods suggests that considerable differences in the resistivity may be anticipated depending on the orientational and morphological configurations of the {alpha}{prime} particles. Finite element analysis of the computed resistance of an assembly of lenticular shaped particles indicates that series resistor or parallel resistor approximations are inaccurate and can lead to an underestimation of the predicted amount of {alpha}{prime} in the sample by 15% or more. Comparison of the resistivity of a simulated network of partially transformed grains or portions of grains suggests that a correction to the measured resistivity allows quantification of the amount of {alpha}{prime} phase in the microstructure with minimal consideration of how the {alpha}{prime} morphology may evolve. It is found that the average of the series and parallel resistor approximations provide the most accurate relationship between the measured resistivity and the amount of {alpha}{prime} phase. The methods described here are applicable to any evolving two-phase microstructure in which the resistance difference between the two phases is measurable.

  11. Epilepsy (partial)

    PubMed Central

    2011-01-01

    Introduction About 3% of people will be diagnosed with epilepsy during their lifetime, but about 70% of people with epilepsy eventually go into remission. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of starting antiepileptic drug treatment following a single seizure? What are the effects of drug monotherapy in people with partial epilepsy? What are the effects of additional drug treatments in people with drug-resistant partial epilepsy? What is the risk of relapse in people in remission when withdrawing antiepileptic drugs? What are the effects of behavioural and psychological treatments for people with epilepsy? What are the effects of surgery in people with drug-resistant temporal lobe epilepsy? We searched: Medline, Embase, The Cochrane Library, and other important databases up to July 2009 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 83 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: antiepileptic drugs after a single seizure; monotherapy for partial epilepsy using carbamazepine, gabapentin, lamotrigine, levetiracetam, phenobarbital, phenytoin, sodium valproate, or topiramate; addition of second-line drugs for drug-resistant partial epilepsy (allopurinol, eslicarbazepine, gabapentin, lacosamide, lamotrigine, levetiracetam, losigamone, oxcarbazepine, retigabine, tiagabine, topiramate, vigabatrin, or zonisamide); antiepileptic drug withdrawal for people with partial or generalised epilepsy who are in remission; behavioural and psychological treatments for partial or generalised epilepsy (biofeedback, cognitive behavioural therapy (CBT), educational programmes, family counselling, relaxation therapy (alone or plus behavioural modification therapy, yoga); and surgery for drug-resistant temporal lobe epilepsy ( lesionectomy, temporal lobectomy, vagus nerve stimulation as adjunctive therapy). PMID:21549021

  12. Anchorage reinforcement with a fixed functional appliance during protraction of the mandibular second molars into the first molar extraction sites.

    PubMed

    Chhibber, Aditya; Upadhyay, Madhur

    2015-07-01

    Protraction of posterior teeth into edentulous spaces is a challenge. This report describes the treatment of a 19-year-old woman with missing mandibular first molars owing to caries. A fixed functional appliance was used for anchorage reinforcement during mandibular second molar protraction. Eight millimeters of bilateral protraction was done with bodily mesial movement of the molars and no lingual tipping of the incisors. PMID:26124039

  13. Fusion of complex odontome with permanent mandibular molar

    PubMed Central

    Talari, Bharathi H.; Ananda, Divya; Prince, Christo N.; Annaporna, Chandrakala S.; Pranavadhyani

    2012-01-01

    Odontomas are malformation of the dental tissue, arising during normal tooth development. They are usually asymptomatic, but often associated with tooth eruption disturbance. This article reports a case of complex odontome in a 23-year-male, which hampered the eruption of mandibular right second molar as well devitalization of first molar. PMID:23066237

  14. Nonsurgical Endodontic Management of a Molar-Incisor Malformation-affected Mandibular First Molar: A Case Report.

    PubMed

    Yue, Wonyoung; Kim, Euiseong

    2016-04-01

    A molar-incisor malformation (MIM) is a newly reported type of dental anomaly that involves a characteristic root malformation in permanent first molars and deciduous second molars and a crown defect in permanent central incisors. This case report describes a nonsurgical root canal treatment of a MIM-affected molar by aid of a reformatted axial view of the tooth cone-beam computed tomography (CBCT). A MIM-affected molar has calcified canal orifices and a few immature accessory furcal canals. Conventional root canal treatment with the aid of CBCT followed by resin restoration was performed on the tooth. The malformed roots of MIM teeth generally make it difficult to apply conventional endodontic treatment; however, it was possible to do with the aid of the reformatted axial view of the CBCT. PMID:26706790

  15. Correlations between FDG PET glucose uptake-MRI gray matter volume scores and apolipoprotein E ?4 gene dose in cognitively normal adults: a cross-validation study using voxel-based multi-modal partial least squares.

    PubMed

    Chen, Kewei; Ayutyanont, Napatkamon; Langbaum, Jessica B S; Fleisher, Adam S; Reschke, Cole; Lee, Wendy; Liu, Xiaofen; Alexander, Gene E; Bandy, Dan; Caselli, Richard J; Reiman, Eric M

    2012-05-01

    We previously introduced a voxel-based, multi-modal application of the partial least square algorithm (MMPLS) to characterize the linkage between patterns in a person's complementary complex datasets without the need to correct for multiple regional comparisons. Here we used it to demonstrate a strong correlation between MMPLS scores to characterize the linkage between the covarying patterns of fluorodeoxyglucose positron emission tomography (FDG PET) measurements of regional glucose metabolism and magnetic resonance imaging (MRI) measurements of regional gray matter associated with apolipoprotein E (APOE) ?4 gene dose (i.e., three levels of genetic risk for late-onset Alzheimer's disease (AD)) in cognitively normal, late-middle-aged persons. Coregistered and spatially normalized FDG PET and MRI images from 70% of the subjects (27 ?4 homozygotes, 36 ?4 heterozygotes and 67 ?4 non-carriers) were used in a hypothesis-generating MMPLS analysis to characterize the covarying pattern of regional gray matter volume and cerebral glucose metabolism most strongly correlated with APOE-?4 gene dose. Coregistered and spatially normalized FDG PET and MRI images from the remaining 30% of the subjects were used in a hypothesis-testing MMPLS analysis to generate FDG PET-MRI gray matter MMPLS scores blind to their APOE genotype and characterize their relationship to APOE-?4 gene dose. The hypothesis-generating analysis revealed covarying regional gray matter volume and cerebral glucose metabolism patterns that resembled those in traditional univariate analyses of AD and APOE-?4 gene dose and PET-MRI scores that were strongly correlated with APOE-?4 gene dose (p<1 10(-16)). The hypothesis-testing analysis results showed strong correlations between FDG PET-MRI gray matter scores and APOE-?4 gene dose (p = 8.7 10(-4)). Our findings support the possibility of using the MMPLS to analyze complementary datasets from the same person in the presymptomatic detection and tracking of AD. PMID:22348880

  16. Qualitative and quantitative assessment of relationship between mandibular third molar and angle fracture on North Indian population: A clinico-radiographic study

    PubMed Central

    Yadav, Suresh; Tyagi, Shallu; Puri, Naveen; Kumar, Prince; Kumar, Puneet

    2013-01-01

    Objective: To assess the relationship between impacted mandibular third molar presence and the risk for mandibular angle fracture with the effect of various positions of mandibular third molar and the risk of mandibular angle fracture. Materials and Methods: In the North Indian territory, a total of 289 patients with mandibular angle fractures were studied and evaluated for the possible relationship with impacted third molar on the basis of clinical and panoramic radiographical findings. Results: Results that confirmed the highest risk for mandibular angle fracture was associated with mesioangular angulations (45.42%) followed by vertical (26.34%), distoangular in sequence and least risk was found with bucco-version angulations (2.67%) according to Winter's classification. Additionally, the highest risk of mandibular angle fracture was reported with partially erupted third molar (47.75%), followed by erupted (23.53%) and unerupted third molar (19.38%). Conclusion: The risk for mandibular angle fracture is not only affected by status of eruption, angulations, position, number of roots present in third molar but also by the distance of mandibular third molar from inferior border of mandible and the percentage of remaining amount of bone at the mandibular angle region. PMID:24883029

  17. Replacement of a first molar and 3 second molarsby the mesial inclination of 4 impacted third molars in an adult with a Class II Division 1malocclusion.

    PubMed

    Tomonari, Hiroshi; Yagi, Takakazu; Kuninori, Takaharu; Ikemori, Takahiro; Miyawaki, Shouichi

    2015-06-01

    This case report presents the successful replacement of 1 first molar and 3 second molars by the mesial inclination of 4 impacted third molars. A woman, 23 years 6 months old, had a chief complaint of crowding of her anterior teeth and linguoclination of a second molar on the left side. The panoramic radiographic images showed that the maxillary and mandibular third molars on both sides were impacted. Root resorption on the distal surfaces of the maxillary second molars was suspected. The patient was given a diagnosis of Angle Class II Division 1 malocclusion with severe crowding of the anterior teeth and 4 impacted third molars. After we extracted the treated maxillary second premolars and the second molars on both sides, the treated mandibular second premolar and the second molar on the left side, and the root canal-filled mandibular first molar on the right side, the 4 impacted third molars were uprighted and formed part of the posterior functional occlusion. The total active treatment period was 39 months. The maxillary and mandibular third molars on both sides successfully replaced the first and second molars. The replacement of a damaged molar by an impacted third molar is a useful treatment option for using sound teeth. PMID:26038080

  18. Quantitative prediction and molar description of the environment

    PubMed Central

    Baum, William M.

    1989-01-01

    Molecular explanations of behavior, based on momentary events and variables that can be measured each time an event occurs, can be contrasted with molar explanations, based on aggregates of events and variables that can be measured only over substantial periods of time. Molecular analyses cannot suffice for quantitative accounts of behavior, because the historical variables that determine behavior are inevitably molar. When molecular explanations are attempted, they always depend on hypothetical constructs that stand as surrogates for molar environmental variables. These constructs allow no quantitative predictions when they are vague, and when they are made precise, they become superfluous, because they can be replaced with molar measures. In contrast to molecular accounts of phenomena like higher responding on ratio schedules than interval schedules and free-operant avoidance, molar accounts tend to be simple and straightforward. Molar theory incorporates the notion that behavior produces consequences that in turn affect the behavior, the notion that behavior and environment together constitute a feedback system. A feedback function specifies the dependence of consequences on behavior, thereby describing properties of the environment. Feedback functions can be derived for simple schedules, complex schedules, and natural resources. A complete theory of behavior requires describing the environment's feedback functions and the organism's functional relations. Molar thinking, both in the laboratory and in the field, can allow quantitative prediction, the mark of a mature science. PMID:22478030

  19. Maxillary molar distalization with a bone-anchored pendulum appliance.

    PubMed

    Kircelli, Beyza Hancio?lu; Pekta?, Zafer Ozgr; Kircelli, Cem

    2006-07-01

    To obtain an effective and compliance-free molar distalization without an anchorage loss, we designed the bone-anchored pendulum appliance (BAPA). The aim of this study was to evaluate the stability of the anchoring screw, distalization of the maxillary molars, and the movement of teeth anterior to maxillary first molars. The study group comprised 10 patients (mean age 13.5 +/- 1.8 years) with Class II molar relationship. A conventional pendulum appliance was modified to obtain anchorage from an intraosseous screw instead of the premolars. The screw was placed in the anterior paramedian region of the median palatal suture. Skeletal and dental changes were measured on cephalograms, and dental casts were obtained before and after distalization. A super Class I molar relationship was achieved in a mean period of 7.0 +/- 1.8 months. The maxillary first molars distalized an average of 6.4 +/- 1.3 mm in the region of the dental crown by tipping distally an average of 10.9 degrees +/- 2.8 degrees . Also, the maxillary second premolar and first premolar moved distally an average of 5.4 +/- 1.3 mm and 3.8 +/- 1.1 mm, respectively. The premolars tipped significantly distally. No anterior incisor movement was detected. The BAPA was found to be an effective, minimally invasive, and compliance-free intraoral distalization appliance for achieving both molar and premolar distalization without any anchorage loss. PMID:16808573

  20. Three-dimensional quantitative analysis of adhesive remnants and enamel loss resulting from debonding orthodontic molar tubes

    PubMed Central

    2014-01-01

    Aims Presenting a new method for direct, quantitative analysis of enamel surface. Measurement of adhesive remnants and enamel loss resulting from debonding molar tubes. Material and methods Buccal surfaces of fifteen extracted human molars were directly scanned with an optic blue-light 3D scanner to the nearest 2 μm. After 20 s etching molar tubes were bonded and after 24 h storing in 0.9% saline - debonded. Then 3D scanning was repeated. Superimposition and comparison were proceeded and shape alterations of the entire objects were analyzed using specialized computer software. Residual adhesive heights as well as enamel loss depths have been obtained for the entire buccal surfaces. Residual adhesive volume and enamel loss volume have been calculated for every tooth. Results The maximum height of adhesive remaining on enamel surface was 0.76 mm and the volume on particular teeth ranged from 0.047 mm3 to 4.16 mm3. The median adhesive remnant volume was 0.988 mm3. Mean depths of enamel loss for particular teeth ranged from 0.0076 mm to 0.0416 mm. Highest maximum depth of enamel loss was 0.207 mm. Median volume of enamel loss was 0.104 mm3 and maximum volume was 1.484 mm3. Conclusions Blue-light 3D scanning is able to provide direct precise scans of the enamel surface, which can be superimposed in order to calculate shape alterations. Debonding molar tubes leaves a certain amount of adhesive remnants on the enamel, however the interface fracture pattern varies for particular teeth and areas of enamel loss are present as well. PMID:25208969

  1. Lingual Guttering Technique for Removal of Impacted Mandibular Third Molars

    PubMed Central

    Kale, Tejraj P; Pandit, Vikram S; Patil, Shankargouda; Pawar, Vivek; Shetty, Nisha

    2014-01-01

    Background: To assess the clinical feasibility of lingual bone guttering technique for surgical extraction of mandibular third molars. Materials and Methods: 20 patients with thick lingual cortical plate were included in the study. Surgical extraction of mandibular third molars by lingual bone guttering technique was performed in all the subjects. These subjects were evaluated for integrity of lingual cortical plate and sensation of lingual nerve postoperatively. Results: All extractions done by lingual bone guttering technique were clinically feasible to perform and no complications were seen. Conclusion: Lingual bone guttering technique can be used safely in extraction of mandibular third molars with thick lingual cortical plate. PMID:25214725

  2. Mandibular first molar with single root and single root canal

    PubMed Central

    Munavalli, Anil; Kambale, Sharnappa; Ramesh, Sachhi; Ajgaonkar, Nishant

    2015-01-01

    Mandibular molars demonstrate considerable anatomic complexities and abnormalities with respect to number of roots and root canals. Clinicians should be aware that there is a possibility of the existence of a fewer number of roots and root canals than the normal root canal anatomy. Mandibular first molar with a single root and single canal was diagnosed with the aid of dental operating microscope and multiple angled radiographs. This case report presents a rare case of successful endodontic management of mandibular first molar with a single root and root canal. PMID:26180424

  3. Molar heat capacity and entropy of calcium metal

    USGS Publications Warehouse

    Hemingway, B.S.; Robie, R.A.; Chase, M.W.

    1997-01-01

    The heat capacity of calcium has been measured at 85 mean temperatures between T ??? 8 K and T ??? 369 K using an adiabatically-shielded calorimeter in an intermittent heating mode. At T = 298.15 K, the recommended values for the molar heat capacity, molar entropy, and molar enthalpy increment referred to T = 0 are (25.77 ?? 0.08) J??K-1??mol-1, (42.90 ?? 0.11) J??K-1??mol-1, and (5811 ?? 12) J??mol-1, respectively. The uncertainties are twice the standard deviation of the mean. ?? 1997 Academic Press Limited.

  4. Odontoblast response to cavity preparation with Er:YAG laser in rat molars: an immunohistochemical study.

    PubMed

    Shigetani, Yoshimi; Suzuki, Hironobu; Ohshima, Hayato; Yoshiba, Kunihiko; Yoshiba, Nagako; Okiji, Takashi

    2013-07-01

    This study aimed to examine the dynamics of odontoblast-lineage cells following cavity preparation with erbium:yttrium-aluminum-garnet (Er:YAG) laser in rat molars. Cavity preparation was made with Er:YAG laser in the mesial surface of the maxillary left first molar of 8-week-old Wistar rats. Contralateral first molar served as unirradiated control. Immediately, 6 and 12h and 1, 2, 3, 5 and 7days after the lasing (n=5, each), specimens were collected and processed for immunohistochemistry for heat-shock protein (HSP)-25 and nestin as markers for odontoblast-lineage cells. Cell proliferation assay using bromodeoxyuridine (BrdU) labeling was also performed. Unirradiated teeth showed HSP-25- and nestin-immunoreactivity in odontoblasts. At 6-12h after irradiation, the odontoblastic layer was disorganized and some of odontoblasts lost the immunoreactivity to HSP-25 and nestin. At 1-2days, however, HSP-25- and nestin-immunoreactivities in the odontoblast layer showed a noticeable recovery, resulting in the rearrangement of odontoblast-like cells intensely immunoreactive to HSP-25 and nestin at 3-7days. BrdU-positive cells showed a significant increase at 2days (P<0.05 vs. immediate previous time point; one-way analysis of variance and Scheff post hoc test), peaked at 3days and then decreased significantly (P<0.05). It was concluded that under the present experimental condition in rat molars, cavity preparation with Er:YAG laser induced mild and reversible damage to odontoblasts. The reparative process was characterized by the rearrangement of HSP-25- and nestin-immunoreactive odontoblast-like cells, which took place subsequent to the odontoblastic layer disorganization with partial loss of these immunoreactivities. PMID:22736273

  5. Solvation molar enthalpies and heat capacities of n-alkanes and n-alkylbenzenes on stationary phases of wide-ranging polarity.

    PubMed

    Lebrn-Aguilar, Rosa; Quintanilla-Lpez, Jess Eduardo; Santiuste, Jos Mara

    2010-12-01

    A comparison of the most usual gas chromatographic methods for the calculation of partial molar enthalpies of solvation (?(sol)H(o)) has been carried out. Those methods based on the fitting of lnV(g) or ln(k/T) vs. 1/T and ln(k/T) vs. (1/T and the temperature arrangement, T(a)) are the most adequate ones for obtaining ?(sol)H(o) values. However, the latter is the only reliable option for ?(sol)H(o) estimation when commercial WCOT capillary columns are used, since in this case the estimation of some variables involved in the V(g) determination is less accurate or even impossible. Consequently, in this paper, ?(sol)H(o) obtained from ln(k/T) vs. (1/T+T(a)) fitting at 373.15 and 298.15K for n-alkanes and n-alkylbenzenes on 12 commercial capillary columns coated with stationary phases covering the 203-3608 McReynolds polarity range are reported. Moreover, molar heat capacities of solvation at constant pressure (?(sol)C(p)(o)) have also been calculated using this method. A clear influence on ?(sol)H(o) of the type and content of the substitution group in the stationary phase was observed. In addition, a linear relationship of ?(sol)C(p)(o) with the van der Waals volume of the n-alkanes and the temperature gradient of density of the stationary phase was found. The effect of the size of the hydrocarbon on both thermodynamic variables was also investigated. PMID:21040924

  6. Reanalysis of the Lukeino molar (KNM-LU 335).

    PubMed

    Ungar, P S; Walker, A; Coffing, K

    1994-06-01

    This paper details a reanalysis of KNM-LU 335, a hominoid mandibular first molar dated to about 6 Ma from the Lukeino Formation, Kenya. Researchers have argued that this molar closely resembles those of modern chimpanzees and may approximate the ancestral morphotype of humans and chimpanzees. The investigation presented here describes a morphometric study of the Lukeino molar and M1s of Homo sapiens, Pan troglodytes, and early australopithecines. Results indicate that KNM-LU 335 differs from both human and chimpanzee M1s in relative distances (measured in three dimensions) between crown fissure termini. Further, the Lukeino molar shares with early australopithecines a pronounced flaring of the buccal surface of the crown not seen for either modern sample. Results of this study do not exclude KNM-LU 335 as a potential ancestral morphotype for Pan and Homo but provide no evidence that this morphotype resembled modern chimpanzees. PMID:8085609

  7. Mandibular First Molar with a Radix Entomolaris: An Endodontic Dilemma

    PubMed Central

    Sarangi, Priyanka; Uppin, Veerendra M

    2014-01-01

    It is known that the mandibular first molar can display significant anatomical variations namely the number of root canals, the number of roots and morphology. Mandibular molars may sometimes have an additional root located lingually (the radix entomolaris) or buccally (the radix paramolaris). If encountered, an awareness and understanding of this unusual root and its canal morphology can contribute to the successful outcome of root canal treatment. This case report discusses endodontic treatment of a mandibular first molar with a radix entomolaris, which is a rare entity and poses as an endodontic dilemma for the clinician with respect to diagnosis and subsequent treatment. Clinicians should be aware of these unusual root morphologies in the mandibular first molar which needs strategic treatment as unfilled canals remain a nidus for infection and can compromise treatment outcome. PMID:24910685

  8. Characteristics of molar pregnancy in a 12 year old.

    PubMed Central

    Chapman, G. W.

    1996-01-01

    Gestational trophoblastic disease rarely is reported in early teens. This article describes a 12-year-old black female with molar disease, in which the characteristics and treatment are not dissimilar from adults. PMID:8990807

  9. Determining Molar Combining Ratios Using Radioisotopes--A Student Experiment

    ERIC Educational Resources Information Center

    Sears, Jerry A.

    1976-01-01

    Outlines an experimental procedure in which an iodine radioisotope is used to determine molar combining ratios of lead and silver with the iodine. Tables and graphs show the definitive results that should be attainable. (CP)

  10. Treatment of a Maxillary First Molar with Two Palatal Roots

    PubMed Central

    Asghari, Vahideh; Rahimi, Saeed; Ghasemi, Negin; Talebzadeh, Bita; Norlouoni, Ahmad

    2015-01-01

    Thorough knowledge of the morphology and internal anatomy of the root canal system is essential, because it determines the successful outcome of endodontic treatment. The main goal of endodontic treatment is to prevent apical periodontitis and/or to promote the healing of periapical lesion. Presence of two canals or roots on the palatal side of the first maxillary molar has rarely been reported. This case report presents a maxillary first molar with two separate palatal roots. PMID:26523146

  11. Treatment of a Maxillary First Molar with Two Palatal Roots.

    PubMed

    Asghari, Vahideh; Rahimi, Saeed; Ghasemi, Negin; Talebzadeh, Bita; Norlouoni, Ahmad

    2015-01-01

    Thorough knowledge of the morphology and internal anatomy of the root canal system is essential, because it determines the successful outcome of endodontic treatment. The main goal of endodontic treatment is to prevent apical periodontitis and/or to promote the healing of periapical lesion. Presence of two canals or roots on the palatal side of the first maxillary molar has rarely been reported. This case report presents a maxillary first molar with two separate palatal roots. PMID:26523146

  12. Treatment of Ectopic Permanent Maxillary First Molar Using a K-loop.

    PubMed

    Nam, Ok Hyung; Ahn, Hyo Jung; Kim, Mi Sun; Park, Jae-Hong

    2015-01-01

    Ectopic eruption of permanent maxillary first molar can cause root resorption of adjacent primary second molar, thus leading to early loss of primary maxillary second molar. Therefore, it is necessary to correct ectopic maxillary first molar. This case report demonstrates that K-loop can be used as a simple, comfortable, and easier method to correct ectopic eruption of permanent maxillary first molar in existing severe root resorption on adjacent primary second molar. PMID:26161613

  13. Kissing molars extraction: Case series and review of the literature

    PubMed Central

    Arjona-Amo, Manuel; Torres-Carranza, Eusebio; Batista-Cruzado, Antonio; Serrera-Figallo, Maria-Angeles; Crespo-Torres, Santos; Belmonte-Caro, Rodolfo; Albisu-Andrade, Claudio; Gutiérrez-Pérez, José-Luis

    2016-01-01

    Kissing molars are a very rare form of inclusion defined as molars included in the same quadrant, with occlusal surfaces contacting each other within a single dental follicle. We present four cases of this pathology: a 35 year-old male, referred to the Oral and Maxillofacial Surgery Department of the Hospital Virgen del Rocio in Seville, and three females of 24, 26, and 31 years, all of which had kissing molars that were treated by tooth extraction. We have found only 10 cases published in the medical literature in which this type of inclusion is briefly described, none of which elaborate on the surgical technique employed. In these cases, the indication for surgery is established when there is a history of recurring infections or cystic lesions associated with dental inclusions. The extraction of kissing molars requires an exhaustive comprehension of the anatomy of the region involved, sufficiently developed surgical abilities, and an extensive planning process. Key words:Impacted molar, kissing molar, surgical extraction. PMID:26855716

  14. Prevalence of Taurodont molars in a North Indian population

    PubMed Central

    Bharti, Ramesh; Chandra, Anil; Tikku, Aseem Prakash; Arya, Deeksha

    2015-01-01

    Background: It is very important for dentists to be familiar with anomalies of teeth not only for the clinical complications but also their management. Taurodontism also provides a valuable clue in detecting its association with various syndromes and other systemic conditions. The purpose of this study was to assess the prevalence of Taurodont molars among a North Indian population. Materials and Methods: A total of 1000 patients full-mouth periapical radiographs were screened. The radiographs were evaluated under optimal conditions using double magnifying glasses. A total of 7615 molars (including third molars) were evaluated. The relative incidence and the correlations regarding the location of Taurodont teeth (right versus left side and maxillary versus mandibular) were analyzed using the Chi-square test. Results: Twenty-eight patients were found to have a Taurodont molar (11 women and 17 men [P = 0.250]). The prevalence of Taurodont molar was 2.8%. Males had a higher prevalence rate than females (3.4% vs. 2.2%, respectively). A cluster analysis of total Taurodonts in the mandible (45%) versus maxilla (55%) of both males and females combined showed a statistically significant difference (P < 0.05). Conclusion: The occurrence of Taurodontism is basically based on racial expression in different populations. These variations in prevalence between different populations may be due to ethnic variations. The occurrence of Taurodont molars among this Indian population was rare. PMID:25767357

  15. Root canal morphology of South Asian Indian maxillary molar teeth

    PubMed Central

    Singh, Shishir; Pawar, Mansing

    2015-01-01

    Objective: The objective was to study the root canal morphology of South Asian Indian Maxillary molars using a tooth clearing technique. Materials and Methods: Hundred teeth each comprising of first, second, and third molars collected from different dental schools and clinics in India were subjected to standard dye penetration, decalcification and clearing procedure before being studied. Results: The first molar mesiobuccal roots exhibited 69% Type I, 24% Type II, 4% Type IV, 2% Type V, and 1% exhibited a Vertuccis Type VIII canal anatomy. In the group with three separate roots the second molar mesiobuccal roots in exhibited 80.6% Type I, 15.3% Type II, 2.7% Type IV, and 1.4% Type V canal anatomy while the third molars mesiobuccal roots exhibited 57.4% Type I, 32% Type II, 2.1% Type III, 8.5% Type IV, 1% had a Type V canal anatomy in the similar group. Conclusion: A varied root canal anatomy was seen in the mesiobuccal root canal of the maxillary molars. PMID:25713497

  16. Genetic integration of molar cusp size variation in baboons

    PubMed Central

    Koh, Christina; Bates, Elizabeth; Broughton, Elizabeth; Do, Nicholas T.; Fletcher, Zachary; Mahaney, Michael C.; Hlusko, Leslea J.

    2010-01-01

    Many studies of primate diversity and evolution rely on dental morphology for insight into diet, behavior, and phylogenetic relationships. Consequently, variation in molar cusp size has increasingly become a phenotype of interest. In 2007 we published a quantitative genetic analysis of mandibular molar cusp size variation in baboons. Those results provided more questions than answers, as the pattern of genetic integration did not fit predictions from odontogenesis. To follow up, we expanded our study to include data from the maxillary molar cusps. Here we report on these later analyses, as well as inter-arch comparisons with the mandibular data. We analyzed variation in two-dimensional maxillary molar cusp size using data collected from a captive pedigreed breeding colony of baboons, Papio hamadryas, housed at the Southwest National Primate Research Center. These analyses show that variation in maxillary molar cusp size is heritable and sexually dimorphic. We also estimated additive genetic correlations between cusps on the same crown, homologous cusps along the tooth row, and maxillary and mandibular cusps. The pattern for maxillary molars yields genetic correlations of one between the paracone-metacone and protocone-hypocone. Bivariate analyses of cuspal homologues on adjacent teeth yield correlations that are high or not significantly different from one. Between dental arcades, the non-occluding cusps consistently yield high genetic correlations, especially the metaconid-paracone and metaconid-metacone. This pattern of genetic correlation does not immediately accord with the pattern of development and/or calcification, however these results do follow predictions that can be made from the evolutionary history of the tribosphenic molar. PMID:20034010

  17. Molar Intrusion in Open-bite Adults Using Zygomatic Miniplates.

    PubMed

    Marzouk, Eiman S; Abdallah, Essam Mohamed; El-Kenany, Walid A

    2015-01-01

    The aim of this study is to evaluate the skeletal, dental and soft tissue changes that arise after intrusion of the maxillary molars using zygomatic miniplates in adult skeletal anterior open bite patients. In addition to measuring the amount and rate of molar intrusion; with special emphasis on changes in the axial inclination of the intruded molars. The study group was composed of 13 anterior open bite patients (mean age 18 years, 8 months 2 years, 2 months) with posterior dentoalveolar excess. Mini-plates were placed in the zygomatic buttress bilaterally. The upper arch was segmentally leveled and a double Trans-Palatal Arch (TPA) was bonded. Closed NiTi coil spring was placed bilaterally between the book of the mini-plate just mesial and distal to the first molar buccal tube applying intrusive force of 450 gper side. Lateral and posteroanterior cephalograms were taken before intrusion (T1: post upper segmental leveling) and after intrusion (T2). Comparison between means before and after the intrusion was done using Wilcoxon Signed Ranks test (WSRT). Mandibular autorotation followed the molar intrusion, SNB and SN-Pog angles significantly increased while the ANB, MP-SN angle and N-S-Gn angle significantly decreased. The mean amount of accomplished molar intrusion was 3.1mm 0.74mm, with a rate of 0.36mm per month 0.08mm per month and a bite closure of 6.55mm 1.83mm. There was no significant buccal tip in the right and left molars upon intrusion. Conclusion: Miniplates zygomatic anchorage can be used effectively for skeletal open bite correction through posterior dento-alveolar intrusion. Intrusion of the posterior teeth with skeletal anchorage induced counterclockwise rotation of the mandible and, as a consequence, corrected the anteroposterior intermaxillary relationship with a dramatic improvement in the facial soft tissue convexity. PMID:26349291

  18. Dynamics and rheology of high molar mass polyethylene oxide solutions

    NASA Astrophysics Data System (ADS)

    Shetty, Abhishek; Solomon, Michael

    2009-03-01

    We report dynamic light scattering (DLS), bulk rheology and turbulent drag reduction (TDR) measurements that investigate the structure and dynamics of high molar mass PEO solutions. Steady shear rheology of high molar mass PEO solutions, when modeled by the FENE-P constitutive equation, was consistent with viscoelastic relaxation times much larger than predicted by single polymer, dilute solution theory. DLS of dilute PEO solutions showed a single relaxation mode in the decay time distribution, which scales as q-3 rather than the q-2 scaling expected of diffusive dynamics. We interpret this result as consistent with the internal dynamics of large multichain domains, clusters or aggregates in the high molar mass PEO solutions. By means of DLS, we also show that the aggregation state of dilute solutions of high molar mass PEO can be manipulated by addition of the chaotropic salt guanidine sulfate or the divalent salt magnesium sulfate. Addition of these salts shifts the power law scaling of the relaxation time from q-3 to q-2. This shift of relaxation time scaling from one indicative of aggregate dynamics (q-3) to one characteristic of polymer center-of-mass diffusion (q-2) shows that these salts are effective de-aggregation agents for PEO. We discuss the results in light of the potential connection between aggregation behavior and polymer TDR of high molar mass PEO.

  19. Aberration in the palatal root of the maxillary first molar

    PubMed Central

    Rajalbandi, Sandeep; Shingte, Sandhya Narayan; Sundaresh, K J; Mallikarjuna, Rachappa

    2013-01-01

    Thorough knowledge of root canal morphology is essential for the endodontic therapy. Variations in the root and root canal morphology, especially in multirooted teeth, are a constant challenge for diagnosis and management. The dentist needs to be familiar with the various root canal configurations and their variations for successful endodontic therapy. There are rare variations in canal number and configuration in maxillary molars, which could affect treatment outcome. Two lingual root structures are occasionally found on human permanent maxillary molars. One of these is the normal lingual root, which is always present, the other is a supernumerary structure which can be located either mesiolingually (radix mesiolingualis) or distolingually (radix distolingualis). The purpose of this paper is to review the literature and to demonstrate a case report which describes the successful non-surgical endodontic management of an unusual maxillary first molar with four separate roots and four canals. PMID:23632609

  20. Partial oxidation catalyst

    DOEpatents

    Krumpelt, Michael (Naperville, IL); Ahmed, Shabbir (Bolingbrook, IL); Kumar, Romesh (Naperville, IL); Doshi, Rajiv (Downers Grove, IL)

    2000-01-01

    A two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion. The dehydrogenation portion is a group VIII metal and the oxide-ion conducting portion is selected from a ceramic oxide crystallizing in the fluorite or perovskite structure. There is also disclosed a method of forming a hydrogen rich gas from a source of hydrocarbon fuel in which the hydrocarbon fuel contacts a two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion at a temperature not less than about 400.degree. C. for a time sufficient to generate the hydrogen rich gas while maintaining CO content less than about 5 volume percent. There is also disclosed a method of forming partially oxidized hydrocarbons from ethanes in which ethane gas contacts a two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion for a time and at a temperature sufficient to form an oxide.

  1. Sex assessment by molar odontometrics in North Indian population

    PubMed Central

    Narang, Ramandeep Singh; Manchanda, Adesh S.; Singh, Balwinder

    2015-01-01

    Introduction: Human identification is based on scientific principles, mainly involving dental records, fingerprints, estimation of age, postmortem reports, differentiation by blood groups, and DNA comparisons. Sex assessment is one of the prime factors employed to assist with the identification of an individual. Aims and Objective: To investigate univariate sex differences in the dimensions of permanent first molars and to assess sex, based on buccolingual (BL) and mesiodistal (MD) dimensions of permanent first molars in a population of north India. In addition, the study intended to evaluate the reliability of dimensional variation of these teeth in assessment of sex among the population. Materials and Methods: The study sample consists of 410 adult individuals (200 males and 210 females), from a north Indian population. The BL and MD diameters of the permanent first molars were measured using digital vernier callipers. Results: It was observed statistically significant difference between males and females with P < 0.05, in maxillary casts in both BL and MD dimensions; but only in the MD dimension in mandibular casts. A high level of sexual dimorphism of 7.7% was found in the BL dimension of the maxillary right first molar. The accuracy of sex assessment by each dimension was deliberated by univariate analyses with an overall accuracy ranging from 67.5 to 88% for various dimensions. Conclusion: Sexual dimorphism of teeth is population specific and among north Indian population, BL and MD dimensions in maxillary first molar and MD dimension in mandibular first molar can be used for sex assessment. PMID:25709321

  2. Endodontic management of a maxillary molar with three mesiobuccal canals.

    PubMed

    Gundam, Sirisha; Maddu, Radhika; Gurram, Sindhura Reddy

    2014-01-01

    It is imperative that the clinician should have comprehensive knowledge about the normal anatomy and its variations of the teeth as the deviations from the usual are very common. An increased awareness of unusual anatomy and a better understanding of the root canal system guide the clinician in accurate diagnosis and treatment of such variations in order to achieve a successful endodontic outcome. The maxillary first molar has been shown to have a wide variation in respect to the number of canals specifically noted in the mesiobuccal root. The current case report shows the successful management of a maxillary molar in which the mesiobuccal root had three canals. PMID:25505997

  3. Endodontic Management of a Maxillary Molar with Three Mesiobuccal Canals

    PubMed Central

    Gundam, Sirisha; Maddu, Radhika; Gurram, Sindhura Reddy

    2014-01-01

    It is imperative that the clinician should have comprehensive knowledge about the normal anatomy and its variations of the teeth as the deviations from the usual are very common. An increased awareness of unusual anatomy and a better understanding of the root canal system guide the clinician in accurate diagnosis and treatment of such variations in order to achieve a successful endodontic outcome. The maxillary first molar has been shown to have a wide variation in respect to the number of canals specifically noted in the mesiobuccal root. The current case report shows the successful management of a maxillary molar in which the mesiobuccal root had three canals. PMID:25505997

  4. Survival rates of porcelain molar crowns-an update.

    PubMed

    Kassem, Amr Shebl; Atta, Osama; El-Mowafy, Omar

    2010-01-01

    The aim of this study was to identify recent studies that dealt with the clinical performance of porcelain molar crowns and to explore the possibility of grouping the findings from similar studies together to draw overall conclusions. A MEDLINE literature search was conducted in early 2009 covering the preceding 12 years. Seventeen studies were indentified. However, only seven met the specific inclusion criteria and were analyzed. Among seven studies, five European countries were covered. Five studies reported on Procera AllCeram molar crowns while one reported on In-Ceram Alumina and Spinell crowns and another on CEREC crowns. For comparison, one additional study that reported on premolar crowns was included. In the five Procera AllCeram studies, 235 molar crowns were evaluated for 5 or more years, of which 24 failed. When the results of the five studies on the performance of Procera AllCeram molar crowns were considered collectively, an overall failure rate of 10.2% was found at 5 or more years. Int J Prosthodont 2010;23:60-62. PMID:20234895

  5. Non-compliance Appliances for Upper Molar Distalization: An Overview.

    PubMed

    Noorollahian, Saeed; Alavi, Shiva; Shirban, Farinaz

    2015-01-01

    Tooth Size Arch-length Discrepancy (TSALD) is a common problem in orthodontics. Its clinical signs are tooth crowding, impaction and incisor proclination. The treatment options are dental arch expansion or tooth mass reduction (stripping or extraction). The "extraction versus non-extraction" controversy has been widely debated in the orthodontic literature. Distalization is a kind of arch expansion in anetro-posterior dimension. Several studies have evaluated both the therapeutic effectiveness and the side effects of the appliances for this method of space gaining. In some cases molar distalization is preferred, e.g., a patient with acceptable profile and skeletal pattern and half cusp Class II molar malocclusion or even less. In some cases molar distalization is the only way, e.g., the patient with previous upper premolar extraction and excessive overijet, or a skeletal Class III patient with previous upper premolar extraction needed upper anterior teeth retraction to create reverse overjet aspre surgical orthodontic decompensation. In this review article, we described non-compliance upper molar distalizing appliances. PMID:26720949

  6. Anterior tympanic plate fracture following extraction of the lower molar

    PubMed Central

    2016-01-01

    The present case report describes an external auditory canal injury following extraction of the lower molar. The external auditory canal was torn in the same fashion that occurs in an anterior tympanic plate fracture. This case demonstrates one of the rare complications associated with dental extractions. PMID:26904496

  7. Anterior tympanic plate fracture following extraction of the lower molar.

    PubMed

    Kim, Yeon-Ho; Kim, Moon-Key; Kang, Sang-Hoon

    2016-02-01

    The present case report describes an external auditory canal injury following extraction of the lower molar. The external auditory canal was torn in the same fashion that occurs in an anterior tympanic plate fracture. This case demonstrates one of the rare complications associated with dental extractions. PMID:26904496

  8. Unilateral maxillary molar distalization with zygoma-gear appliance.

    PubMed

    Kilkis, Dogan; Bayram, Mehmet; Celikoglu, Mevlut; Nur, Metin

    2012-08-01

    The aim of this study was to present the orthodontic treatment of a 15-year-old boy with a unilateral maxillary molar distalization system, called the zygoma-gear appliance. It consisted of a zygomatic anchorage miniplate, an inner bow, and a Sentalloy closed coil spring (GAC International, Bohemia, NY). A distalizing force of 350 g was used during the distalization period. The unilateral Class II malocclusion was corrected in 5 months with the zygoma-gear appliance. The maxillary left first molar showed distalization of 4 mm with an inclination of 3. The maxillary premolars moved distally with the help of the transseptal fibers. In addition, there were slight decreases in overjet (-0.5 mm) and maxillary incisor inclination (-1), indicating no anchorage loss from the zygoma-gear appliance. Preadjusted fixed appliances (0.022 0.028-in, MBT system; 3M Unitek, Monrovia, Calif) were placed in both arches to achieve leveling and alignment. After 14 months of unilateral distalization with the zygoma-gear appliance and fixed appliances, Class I molar and canine relationships were established with satisfactory interdigitation of the posterior teeth. Acceptable overjet and overbite were also achieved. This article shows that this new system, the zygoma-gear appliance, can be used for unilateral maxillary molar distalization without anchorage loss. PMID:22858341

  9. Factors associated with molar incisor hypomineralization in Thai children.

    PubMed

    Pitiphat, Waranuch; Luangchaichaweng, Sarunporn; Pungchanchaikul, Patimaporn; Angwaravong, Onauma; Chansamak, Nusara

    2014-08-01

    Molar incisor hypomineralization (MIH) is a qualitative developmental enamel defect that affects one to four permanent first molars, with or without involvement of permanent incisors. Its etiology is of systemic origin, but is not well understood. Therefore, we conducted this cross-sectional study to examine pre-, peri-, and postnatal risk factors for MIH among children, 7-8 yr of age, in urban areas of Khon Kaen, Thailand. Molar incisor hypomineralization defects were diagnosed using the European Academy of Pediatric Dentistry criteria. Mothers or primary caregivers were interviewed on maternal medical history and habits during pregnancy, pregnancy and delivery complications, and the child's medical history. Molar incisor hypomineralization defects were observed in 78 (27.7%) of 282 children. Multiple logistic regression analysis showed a statistically significant association between the development of MIH and Cesarean section (adjusted OR = 2.0, 95% CI = 1.1-3.7), complications during vaginal delivery (adjusted OR = 4.5, 95% CI = 1.9-11.0), and severe/chronic illness when under 3 yr of age (adjusted OR = 2.9, 95% CI = 1.6-5.0). There was no association of preterm birth and low birth weight with MIH. The results suggest that Cesarean section, complications during vaginal delivery, and poor health during the first 3 yr of life are independent risk factors for MIH. PMID:24924351

  10. Paradental cyst associated with supernumerary tooth fused with third molar: A rare case report

    PubMed Central

    Prakash, A Ravi; Reddy, P Sreenivas; Rajanikanth, M

    2012-01-01

    Fusion is the union of two tooth buds that are normally separated. Fusion is more frequent in deciduous teeth, particularly in the anterior region. The etiology of fusion is not known. It has been suggested that the pressure of adjacent dental follicles produces their contact and fusion before calcification. There is no difference between men and women in incidence. The term paradental cyst means that such type of cysts that are close proximity with the root of a tooth. A history of recurrent pericoronitis is reported usually and there is often the presence of a communication between the periodontal pocket and the cyst. We present a rare case report where in partially erupted mandibular third molar is fused horizontally with a supernumerary tooth with paradental cyst. PMID:22434950

  11. Paradental cyst associated with supernumerary tooth fused with third molar: A rare case report.

    PubMed

    Prakash, A Ravi; Reddy, P Sreenivas; Rajanikanth, M

    2012-01-01

    Fusion is the union of two tooth buds that are normally separated. Fusion is more frequent in deciduous teeth, particularly in the anterior region. The etiology of fusion is not known. It has been suggested that the pressure of adjacent dental follicles produces their contact and fusion before calcification. There is no difference between men and women in incidence. The term paradental cyst means that such type of cysts that are close proximity with the root of a tooth. A history of recurrent pericoronitis is reported usually and there is often the presence of a communication between the periodontal pocket and the cyst. We present a rare case report where in partially erupted mandibular third molar is fused horizontally with a supernumerary tooth with paradental cyst. PMID:22434950

  12. Pressure, relaxation volume, and elastic interactions in charged simulation cells

    NASA Astrophysics Data System (ADS)

    Bruneval, Fabien; Varvenne, Cline; Crocombette, Jean-Paul; Clouet, Emmanuel

    2015-01-01

    The ab initio calculation of charged supercells within density-functional theory is a necessary step to access several important properties of matter. The relaxation volume of charged point defects or the partial molar volume of ions in solution are two such examples. However, the total energy and therefore the pressure of charged systems is not uniquely defined when periodic boundary conditions are employed. This problem is tightly related to the origin of the electrostatic potential in periodic systems. This effect can be easily observed by modifying the electrostatic convention or modifying the local ionic potential details. We propose an approach to uniquely define the pressures in charged supercells with the use of the absolute deformation potentials. Only with such a definition could the ab initio calculations provide meaningful values for the relaxation volumes and for the elastic interactions for charged defects in semiconductors or ions in solution. The proposed scheme allows one to calculate sensible data even when charge neutrality is not enforced, thus going beyond the classical force-field-based approaches.

  13. Bonded molar tubes--an in vitro evaluation.

    PubMed

    Millett, D T; Letters, S; Roger, E; Cummings, A; Love, J

    2001-10-01

    This study aimed to evaluate the mean shear bond strength of molar tubes with micro-etched bases bonded with either a compomer (Ultra Band-Lok), a resin-modified glass ionomer cement (3M Multi-Cure or Fuji Ortho LC), or a light-cured resin adhesive (Transbond). The amount of adhesive remaining on the tooth surface following tube removal was assessed also. Finally, survival time of molar tubes bonded with each bonding agent was assessed following simulated mechanical fatigue in a ball mill. A total of 120 extracted human third molars were collected and randomly divided into 4 test groups. Thirty teeth (20 to assess debonding force and 10 to assess survival time) were bonded with each adhesive according to the manufacturers' instructions. Debonding was carried out using a Nene M3000 testing machine with a crosshead speed of 0.5 mm/min. The mean shear bond strength of tubes bonded with Transbond was significantly less than that of those bonded with 3M Multi-Cure (P = .0036) or Fuji Ortho LC (P < .0001). Tubes bonded with Ultra Band-Lok also had significantly lower mean shear bond strength than those bonded with Fuji Ortho LC (P = .020). Distribution of adhesive remnant index scores only differed significantly between tubes bonded with 3M Multi-Cure or Transbond. Only I molar tube, bonded with Transbond, debonded in the ball mill at 5 hours, but at 50 hours there was no significant difference in the survival time of tubes bonded with any of the bonding agents. Compomer or resin-modified glass ionomer cements appear to be viable alternatives to light-cured resin adhesive for bonding molar tubes. PMID:11605872

  14. Molar luxations caused by holding water taps. Report of five cases.

    PubMed

    Horie, Norio; Hino, Shunsuke; Fukai, Shunichi; Kaneko, Takahiro; Shimoyama, Tetsuo

    2013-01-01

    Luxation of a primary molar occurs rarely. Here, we describe five cases of primary molar luxation caused by holding a water tap pipe in the mouth during bathing. The patients were aged 16 to 19 months and the mandibular first primary molar was affected in all five cases. The second primary molar had not erupted. It is assumed that the flange of the pipe got stuck in the interdental space between the mandibular primary canine and first primary molar and the affected first molar was pushed out by force with the flange acting as a lever. PMID:24579277

  15. Piezoelectric Versus Conventional Rotary Techniques for Impacted Third Molar Extraction

    PubMed Central

    Jiang, Qian; Qiu, Yating; Yang, Chi; Yang, Jingyun; Chen, Minjie; Zhang, Zhiyuan

    2015-01-01

    Abstract Impacted third molars are frequently encountered in clinical work. Surgical removal of impacted third molars is often required to prevent clinical symptoms. Traditional rotary cutting instruments are potentially injurious, and piezosurgery, as a new osteotomy technique, has been introduced in oral and maxillofacial surgery. No consistent conclusion has been reached regarding whether this new technique is associated with fewer or less severe postoperative sequelae after third molar extraction. The aim of this study was to compare piezosurgery with rotary osteotomy techniques, with regard to surgery time and the severity of postoperative sequelae, including pain, swelling, and trismus. We conducted a systematic literature search in the Cochrane Library, PubMed, Embase, and Google Scholar. The eligibility criteria of this study included the following: the patients were clearly diagnosed as having impacted mandibular third molars; the patients underwent piezosurgery osteotomy, and in the control group rotary osteotomy techniques, for removing impacted third molars; the outcomes of interest include surgery time, trismus, swelling or pain; the studies are randomized controlled trials. We used random-effects models to calculate the difference in the outcomes, and the corresponding 95% confidence interval. We calculated the weighted mean difference if the trials used the same measurement, and a standardized mean difference if otherwise. A total of seven studies met the eligibility criteria and were included in our analysis. Compared with rotary osteotomy, patients undergoing piezosurgery experienced longer surgery time (mean difference 4.13 minutes, 95% confidence interval 2.755.52, P?molars. PMID:26469902

  16. Space loss following premature loss of primary second molars.

    PubMed

    Alnahwi, Hassan H; Donly, Kevin J; Contreras, Claudia I

    2015-01-01

    This study was designed to evaluate the amount of space loss (SL) caused by premature loss of primary second molars, determine whether the eruption status of permanent first molars is an important factor in the amount of SL, and evaluate the effectiveness of space maintainers (SMs) in SL prevention. SL associated with 100 prematurely extracted primary second molars was evaluated in 87 healthy patients. Teeth were divided into groups based on the use of SMs (36 with SM and 64 without SM). Bitewing and periapical radiographs taken before extraction and 6, 12, 24, 36, and 48 months after extraction were used to determine the amount of SL. Not every patient attended every recall appointment, so the sample size varied at different evaluation times. The most significant amount of SL occurred in the first 12 months after extraction. In patients who did not use an SM, at 6 months there was a mean SL of 2.12 mm (SD, 1.65 mm) and at 12 months there was a mean of 4.02 mm (SD, 1.65), with significantly more SL in the first 6 months (P < 0.001). There was no statistically significant difference in the amount of SL found at 12 and 24 months (P > 0.05). When patients without an SM were grouped by the eruption status of the permanent first molar, there was significantly more SL in the groups with unerupted first molars than there was in the groups with erupted first molars at both 6 months (P < 0.001) and 12 months (P < 0.05). At both 6 and 12 months, the amount of SL in patients who had an SM (n = 13 and n = 14, respectively) was not significantly different from the amount of SL in those who did not have an SM (n = 33 and n = 23, respectively). SMs should be placed as soon as possible following tooth extraction to prevent undue SL. Placement of an SM a year or more after extraction has minimal benefit, since most SL takes place within the first year. SL does occur even when SMs are used. PMID:26545280

  17. Treatment of infra-occluded primary molars in patients with dental ageneses.

    PubMed

    Medio, Marie; de la Dure Molla, Muriel

    2014-09-01

    When dental agenesis is encountered, several treatment solutions can be considered: extraction of the primary tooth and closure of the space or, alternatively, conservation of the space with the primary tooth still on the arch until a prosthesis can be placed. In the presence of premolar agenesis, the corresponding primary molar may be infra-occluded relative to the occlusal plane. This situation complicates the treatment plan. Depending on the clinical setting, it can be useful to restore occlusal contacts using composite overlays. We will demonstrate this treatment option via two clinical cases. Tooth conservation helps maintain the bone volume that will later facilitate placement of an implant and limit extrusion of the antagonists as well as tipping of the neighboring teeth. PMID:25092254

  18. Vapor-phase molar Kerr constant values from solution measurements

    NASA Astrophysics Data System (ADS)

    Prezhdo, Victor; Olan, Karol; Prezhdo, Oleg; Zubkova, Valentina

    2015-01-01

    A method is proposed for determination of molar Kerr constants (mK) by extrapolation of the values measured in a series of selected solvents. The mK values of 19 organic compounds were calculated. Most of the compounds cannot be studied in the vapor phase. The discrete-continuum solvation model was applied to investigate the influence of solvent nature on solubility of the compounds under investigation. It is shown that universal interactions between the solvent and solute molecules, including the dispersive, inductive, and dipole-dipole interactions, dominate the solvation process. The optimum model of internal field was chosen to determine the Kerr constant. The values of mKgas measured experimentally coincide with the values of mK??= 0 ? that were obtained by extrapolation of mK?. Hence, this method can be applied to calculate the values of molar Kerr constants on the basis of measurements in solutions.

  19. Molar distalization with the assistance of Temporary Anchorage Devices.

    PubMed

    Palencar, Adrian J

    2015-01-01

    This article describes efficient techniques for distalization of maxillary and mandibular molars with the assistance of Temporary Anchorage Devices (TADs). There are numerous occasions where the distalization of molars is required in lieu of the odontectomy of bicuspids. In the past, extra-oral force has been used, (i.e. Cervical or Combination Head Gear, or intra-oral force, i.e. Posterior Sagittal Appliance, Modified Greenfield Appliance, Williams DMJ 20001, CD Distalizer, Magill Sagittal, Pendulum Appliance, etc.). All the intra-oral appliances have a common denominator the orthodontic clinician has to deal with, the undesirable expression of the Third Law of Newton. The utilization of TADs allows us to circumvent this shortcoming, establishing an absolute anchorage, and thus completely negate the expression of the Third Law of Newton. PMID:25881377

  20. Ectopic 3rd molar tooth in the maxillary antrum.

    PubMed

    Bello, Seidu A; Oketade, Ifeoluwa O; Osunde, Otasowie D

    2014-01-01

    Location of ectopic tooth in a nondentate area like the maxillary antrum is rare. A 17-year-old boy, with one year history of recurrent right facial swelling and radiographic finding of a maxillary third molar tooth located at the posterior wall of the maxillary antrum, is presented. Under endotracheal intubation, the tooth was extracted through a Caldwell-Luc antrostomy approach and patient had an uneventful recovery and has been symptom free for eight months. Ectopic tooth in the maxillary antrum is rare and is commonest with maxillary third molar. It may be symptomless but is more commonly associated with inflammatory symptoms. The treatment of choice is surgical excision which is mostly carried out with Caldwell-Luc approach, even though endoscopic approach is being reported. PMID:25132999

  1. Thermal correction to the molar polarizability of a Boltzmann gas

    SciTech Connect

    Jentschura, U. D.; Puchalski, M.; Mohr, P. J.

    2011-12-15

    Metrology in atomic physics has been crucial for a number of advanced determinations of fundamental constants. In addition to very precise frequency measurements, the molar polarizability of an atomic gas has recently also been measured very accurately. Part of the motivation for the measurements is due to ongoing efforts to redefine the International System of Units (SI), for which an accurate value of the Boltzmann constant is needed. Here we calculate the dominant shift of the molar polarizability in an atomic gas due to thermal effects. It is given by the relativistic correction to the dipole interaction, which emerges when the probing electric field is Lorentz transformed into the rest frame of the atoms that undergo thermal motion. While this effect is small when compared to currently available experimental accuracy, the relativistic correction to the dipole interaction is much larger than the thermal shift of the polarizability induced by blackbody radiation.

  2. Developmental regulations of Perp in mice molar morphogenesis.

    PubMed

    Neupane, Sanjiv; Sohn, Wern-Joo; Rijal, Girdhari; Lee, Ye-Ji; Lee, Sanggyu; Yamamoto, Hitoshi; An, Chang-Hyeon; Cho, Sung-Won; Lee, Youngkyun; Shin, Hong-In; Kwon, Tae-Yub; Kim, Jae-Young

    2014-10-01

    Teraspanin transmembrane protein, Perp (P53 apoptosis effector related to PMP22), which is found in the plasma membrane as a component of the desmosome, is reported to be involved in the morphogenesis of the epithelium and the enamel formation of the incisor. However, its expression pattern and signaling regulation during molar development have not been elucidated in detail. We have examined the precise expression patterns of Perp in developing lower molars and employed the knock-down of Perp by antisense oligodeoxynucleotide treatment during in vitro organ cultivation at embryonic day 13 to define the precise developmental function of Perp. Perp was expressed mainly in the dental lamina and stellate reticulum regions at the bud and cap stages. After Perp knock-down, the tooth germ showed disruption of the dental lamina and stellate reticulum with altered apoptosis and proliferation. The changed expression levels of related signaling molecules from the enamel knot and desmosome were evaluated by real-time quantitative polymerase chain reaction. A renal capsule transplantation method was employed to examine the effects of Perp knock-down on molar crown development. Ultrastructural observations revealed that enamel was deposited more densely in an irregular pattern in the cusp region, and that dentin was hypo-mineralized after Perp knock-down at the cap stage. Thus, Perp might play important roles in the formation and integration of stellate reticulum, dental lamina structure and enamel formation through signaling interactions with the enamel knot and desmosome-related signaling molecules at the cap stage of lower molar development. PMID:24865245

  3. The maxillary second molar - anatomical variations (case report).

    PubMed

    Beshkenadze, E; Chipashvili, N

    2015-01-01

    To be acquainted with dental anatomical specificity is of great importance for dental endodontic treatment algorithm. The subject of present publication is 2 clinical cases of upper second molars, detailed characterization of, which is considered very important for enrichment of anatomical knowledge about dental anatomical variations. In one case, the reason for admission to the clinic of a 38-year-old woman was complains as of esthetic character as well as functional misbalance (disturbance of chewing function due to the damage of orthopedic construction). The patient indicated to the existence of coronary defects of large size aesthetic discomforts, damage and discolouration of old orthopedic construction (denture) in maxillary right molar area. According to the data obtained after clinical and visiographical examinations, chronic periodontitis of 17 teeth was identified as a result of incomplete endodontic treatment. According to the data obtained after clinical and visiographical examinations, the diagnosis of chronic periodontitis of 17 teeth was identified, tooth 17 with 2 roots and 2 canals. In the second clinical case, the reason for admission to the clinic of a 39-year-old woman was severe pain in the upper right molar area. The patient indicated to the caries on the tooth 17. After completion of proper survey clinical and visiographical examinations, acute pulpitis (K04.00) - with three roots and 4 canals was diagnosed. In both cases after the proper examinations and agreement with the patients a treatment plan envisaging: 17 teeth endodontic treatment, filling of caries defects and their preparation on one hand for orthopedic construction (denture) and on the other hand for restoration of anatomical integrity by light-cured composite, was scheduled. The present study is designed to prevent complications of endodontic treatment of the second molar, to optimize diagnosis and treatment algorithm, once again proving reliable information indicating to the individuality of treatment tactics. PMID:25693211

  4. Beyond the molar-molecular distinction: we need multiscaled analyses.

    PubMed

    Hineline, P N

    2001-05-01

    Dinsmoor's (2001) adherence to molecular analyses may require him to assert that molar and molecular principles are mutually exclusive, but to instead analyze the phenomena of avoidance as inherently multiscaled is to follow a well-established practice in the natural sciences. Besides the issue of scale, two-factor theory, which Dinsmoor advocates, has little to say about some important and longstanding results in experiments that qualify as avoidance. PMID:11453624

  5. Five Canalled and Three-Rooted Primary Second Mandibular Molar

    PubMed Central

    Selvakumar, Haridoss; Kavitha, Swaminathan; Bharathan, Rajendran; Varghese, Jacob Sam

    2014-01-01

    A thorough knowledge of root canal anatomy and its variation is necessary for successful completion of root canal procedures. Morphological variations such as additional root canals in human deciduous dentition are rare. A mandibular second primary molar with more than four canals is an interesting example of anatomic variations, especially when three of these canals are located in the distal root. This case shows a rare anatomic configuration and points out the importance of looking for additional canals. PMID:25147744

  6. Case report: A medieval case of molar-incisor-hypomineralisation.

    PubMed

    Curzon, M E J; Ogden, A R; Williams-Ward, M; Cleaton-Jones, P E

    2015-12-18

    Introduction Molar-incisor-hypomineralisation (MIH) has been identified in recent years as a condition affecting the first permanent molars and, in some cases, the permanent incisors. Many factors have been suggested as to its aetiology. Examples of MIH have also been reported in skeletal remains in the past. These historical examples have, however, been for unknown individuals.Case report A skull that has become available for dental examination that is uncertainly attributed to be that of Lady Eleanor Talbot (c.1436-1468) who ended her life as a Carmelite nun in Norwich (England). The dental findings of the examination showed enamel defects of molar teeth 36 and 46, as well as small areas on other molars, and striations of the enamel of permanent anterior teeth consistent with MIH. There is exposure of the roots of some maxillary teeth with resultant root caries. The presence of areas of enamel decalcification commensurate with 'Turner teeth' on 43 and 44 indicates that there were likely to have been periapical abscesses secondary to dental caries of the primary teeth. In addition, there is occlusal wear of all of teeth with extensive calculus and periodontal exposure of the roots of the mandibular incisors. Failed development or very early ante-mortem loss of premolars 15 and 25 is evident, as well as evidence in the same region of a large abscess cavity with extensive maxillary bone destruction. Healing cribra orbitalia, porosity, which is considered to be an indicator of nutritional stress, is visible on the superior aspect of the left orbit.Conclusion A case of MIH is reported in a skull dating from the mid-15th century. PMID:26679138

  7. Fate of the Molar Dental Lamina in the Monophyodont Mouse

    PubMed Central

    Dosed?lov, Hana; Dumkov, Jana; Lesot, Herv; Glocov, Kristna; Kunov, Michaela; Tucker, Abigail S.; Vesel, Iva; Krej?, Pavel; Tich, Frantiek; Hampl, Ale; Buchtov, Marcela

    2015-01-01

    The successional dental lamina (SDL) plays an essential role in the development of replacement teeth in diphyodont and polyphyodont animals. A morphologically similar structure, the rudimental successional dental lamina (RSDL), has been described in monophyodont (only one tooth generation) lizards on the lingual side of the developing functional tooth. This rudimentary lamina regresses, which has been proposed to play a role in preventing the formation of future generations of teeth. A similar rudimentary lingual structure has been reported associated with the first molar in the monophyodont mouse, and we show that this structure is common to all murine molars. Intriguingly, a lingual lamina is also observed on the non-replacing molars of other diphyodont mammals (pig and hedgehog), initially appearing very similar to the successional dental lamina on the replacing teeth. We have analyzed the morphological as well as ultrastructural changes that occur during the development and loss of this molar lamina in the mouse, from its initiation at late embryonic stages to its disappearance at postnatal stages. We show that loss appears to be driven by a reduction in cell proliferation, down-regulation of the progenitor marker Sox2, with only a small number of cells undergoing programmed cell death. The lingual lamina was associated with the dental stalk, a short epithelial connection between the tooth germ and the oral epithelium. The dental stalk remained in contact with the oral epithelium throughout tooth development up to eruption when connective tissue and numerous capillaries progressively invaded the dental stalk. The buccal side of the dental stalk underwent keratinisation and became part of the gingival epithelium, while most of the lingual cells underwent programmed cell death and the tissue directly above the erupting tooth was shed into the oral cavity. PMID:26010446

  8. Extrusion of impacted mandibular second molar using removable appliance

    PubMed Central

    Karthikeyan, M. K.; Prabhakar, Ramachandran; Saravanan, R.; Vikram, N. Raj; Kumar, R. Vinoth; Prasath, R. Eshwara

    2014-01-01

    The purpose of this article is to review the principles of case management of impacted mandibular molars and to illustrate their potential to respond well to treatment. Although the scope of treatment may be influenced by the patient's age, past dental history, severity of impaction, dentoalveolar development, and root form, the case reports demonstrate the inherent potential for good treatment outcome even in the most unfavorable circumstances. PMID:25210378

  9. A Physiological Permeability Study of Third Molar Dentine with Odontoblasts Preserved and Odontoblasts Free Preparations

    PubMed Central

    Ghazali, Farid Che

    2000-01-01

    Introduction Dentine a viable biological tissue forms an intimately related complex with the odontoblasts. Much has been question of the barrier properties of dentine within teeth and between teeth.. In human adults the odontoblasts are fully differentiated post-mitotic cells, which send its cytoplasmic processes into the dentinal tubules, yet various studies in the physic of fluid flow in dentine takes little recognition of its presence. The permeability of dentine has been implicated in a possible hydrodynamic mechanism by which rapid fluid movement in the tubules is thought to depolarise the nerve endings. Objective The innovative aim from this pilot investigation is to contribute to the understanding of the influence of odontoblasts on the permeability of human dentine. Methodology This study describes the permeability in odontoblast preserved and odontoblast free preparations in vitro i.e. comparing fluid flow across dentine in human third molars. The pulp tissues were removed from human third molars leaving the odontoblasts attached to the walls of the chamber. The specimens were then either fixed chemically (odontoblast-preserved specimens) or immersed in NaOH (odontoblast free specimens). Occlusal dentine was exposed by removing the enamel. The exposed dentine was placed in contact with water and the ingress of water into the pulp chamber was observed with a binocular microscope. A microlitre syringe was used to measure the volume of water accumulated at time intervals of several hours for up to 70 hours or more. Results The results showed that spontaneous flow continued in both preparations until equilibrium was reached. The relative final volumes were greater in the odontoblast free preparations than in the odontoblast preserved. Conclusion Water movement through odontoblast free dentine was believed to be driven by capillarity and through odontoblast preserved dentine by capillarity and osmotic pressure.

  10. Molar tooth carbonates and benthic methane fluxes in Proterozoic oceans.

    PubMed

    Shen, Bing; Dong, Lin; Xiao, Shuhai; Lang, Xianguo; Huang, Kangjun; Peng, Yongbo; Zhou, Chuanming; Ke, Shan; Liu, Pengju

    2016-01-01

    Molar tooth structures are ptygmatically folded and microspar-filled structures common in early- and mid-Proterozoic (∼2,500-750 million years ago, Ma) subtidal successions, but extremely rare in rocks <750 Ma. Here, on the basis of Mg and S isotopes, we show that molar tooth structures may have formed within sediments where microbial sulphate reduction and methanogenesis converged. The convergence was driven by the abundant production of methyl sulphides (dimethyl sulphide and methanethiol) in euxinic or H2S-rich seawaters that were widespread in Proterozoic continental margins. In this convergence zone, methyl sulphides served as a non-competitive substrate supporting methane generation and methanethiol inhibited anaerobic oxidation of methane, resulting in the buildup of CH4, formation of degassing cracks in sediments and an increase in the benthic methane flux from sediments. Precipitation of crack-filling microspar was driven by methanogenesis-related alkalinity accumulation. Deep ocean ventilation and oxygenation around 750 Ma brought molar tooth structures to an end. PMID:26739600

  11. From molecular to molar: a paradigm shift in behavior analysis.

    PubMed Central

    Baum, William M

    2002-01-01

    A paradigm clash is occurring within behavior analysis. In the older paradigm, the molecular view, behavior consists of momentary or discrete responses that constitute instances of classes. Variation in response rate reflects variation in the strength or probability of the response class. The newer paradigm, the molar view, sees behavior as composed of activities that take up varying amounts of time. Whereas the molecular view takes response rate and choice to be "derived" measures and hence abstractions, the molar view takes response rate and choice to be concrete temporally extended behavioral allocations and regards momentary "responses" as abstractions. Research findings that point to variation in tempo, asymmetry in concurrent performance, and paradoxical resistance to change are readily interpretable when seen in the light of reinforcement and stimulus control of extended behavioral allocations or activities. Seen in the light of the ontological distinction between classes and individuals, extended behavioral allocations, like species in evolutionary taxonomy, constitute individuals, entities that change without changing their identity. Seeing allocations as individuals implies that less extended activities constitute parts of larger wholes rather than instances of classes. Both laboratory research and everyday behavior are explained plausibly in the light of concrete extended activities and their nesting. The molecular- view, because it requires discrete responses and contiguous events, relies on hypothetical stimuli and consequences to account for the same phenomena. One may prefer the molar view on grounds of elegance, integrative power, and plausibility. PMID:12144313

  12. Decontamination of tried-in orthodontic molar bands.

    PubMed

    Fulford, M R; Ireland, A J; Main, B G

    2003-12-01

    Molar bands are commonly used to retain orthodontic attachments on posterior teeth and due to the variation in the size of such teeth, it is usually necessary to 'try in' several bands before the correct one is selected. A possible concern with re-using such bands is the lack of cross-infection control, even following autoclaving, due to the presence of one or more small bore lumen (the archwire and headgear tubes). The aim of this experiment was, therefore, to determine whether such bands could be successfully decontaminated so that they could be re-used without a cross-infection risk. Two hundred orthodontic molar bands that had previously been tried in patients' mouths, but not cemented into place, were tested. Each band was decontaminated using an enzymatic cleaner/disinfectant and then sterilized using either a downward displacement (n = 100) or a vacuum cycle autoclave (n = 100). Following autoclaving each band was inoculated into brain heart infusion culture broth and incubated at 37 degrees C for 5 days. None of the decontaminated bands exhibited growth after 5 days. It would appear that, using this methodology, there is little risk of a cross-infection hazard occurring with the re-use of previously tried-in and decontaminated molar bands. PMID:14700269

  13. Molar tooth carbonates and benthic methane fluxes in Proterozoic oceans

    PubMed Central

    Shen, Bing; Dong, Lin; Xiao, Shuhai; Lang, Xianguo; Huang, Kangjun; Peng, Yongbo; Zhou, Chuanming; Ke, Shan; Liu, Pengju

    2016-01-01

    Molar tooth structures are ptygmatically folded and microspar-filled structures common in early- and mid-Proterozoic (∼2,500–750 million years ago, Ma) subtidal successions, but extremely rare in rocks <750 Ma. Here, on the basis of Mg and S isotopes, we show that molar tooth structures may have formed within sediments where microbial sulphate reduction and methanogenesis converged. The convergence was driven by the abundant production of methyl sulphides (dimethyl sulphide and methanethiol) in euxinic or H2S-rich seawaters that were widespread in Proterozoic continental margins. In this convergence zone, methyl sulphides served as a non-competitive substrate supporting methane generation and methanethiol inhibited anaerobic oxidation of methane, resulting in the buildup of CH4, formation of degassing cracks in sediments and an increase in the benthic methane flux from sediments. Precipitation of crack-filling microspar was driven by methanogenesis-related alkalinity accumulation. Deep ocean ventilation and oxygenation around 750 Ma brought molar tooth structures to an end. PMID:26739600

  14. Molar tooth carbonates and benthic methane fluxes in Proterozoic oceans

    NASA Astrophysics Data System (ADS)

    Shen, Bing; Dong, Lin; Xiao, Shuhai; Lang, Xianguo; Huang, Kangjun; Peng, Yongbo; Zhou, Chuanming; Ke, Shan; Liu, Pengju

    2016-01-01

    Molar tooth structures are ptygmatically folded and microspar-filled structures common in early- and mid-Proterozoic (~2,500-750 million years ago, Ma) subtidal successions, but extremely rare in rocks <750 Ma. Here, on the basis of Mg and S isotopes, we show that molar tooth structures may have formed within sediments where microbial sulphate reduction and methanogenesis converged. The convergence was driven by the abundant production of methyl sulphides (dimethyl sulphide and methanethiol) in euxinic or H2S-rich seawaters that were widespread in Proterozoic continental margins. In this convergence zone, methyl sulphides served as a non-competitive substrate supporting methane generation and methanethiol inhibited anaerobic oxidation of methane, resulting in the buildup of CH4, formation of degassing cracks in sediments and an increase in the benthic methane flux from sediments. Precipitation of crack-filling microspar was driven by methanogenesis-related alkalinity accumulation. Deep ocean ventilation and oxygenation around 750 Ma brought molar tooth structures to an end.

  15. Efficacy of Postoperative Prophylactic Antibiotic Therapy in Third Molar Surgery

    PubMed Central

    Reddy B, Praveen

    2014-01-01

    Introduction: Surgical extraction of mandibular third molar is the most frequently performed procedure in oral surgery. This procedure is associated with significant postoperative sequelae such as trismus, swelling, pain and infection. The need of antibiotic therapy during the removal of mandibular third molar has been a contentious issue. Method: This study investigated a regimen by using amoxycillin and metronidazole in one group and without using antibiotics in the other. Both the groups were assessed postoperatively on the 1st, 2nd, 5th, 7th and 10th days by the same observer for post operative mouth opening (interincisal distance), presence of a purulent discharge at the site of surgery, pain and swelling. Result: Overall, no statistically significant difference was seen between both the treatment groups when interincisal distance, pain, swelling and purulent discharge were considered. Conclusion: The results of this study failed to show any advantage which was associated with the routine postoperative use of antibiotics in asymptomatic third molar surgeries. PMID:24995236

  16. Molar Macrowear Reveals Neanderthal Eco-Geographic Dietary Variation

    PubMed Central

    Fiorenza, Luca; Benazzi, Stefano; Tausch, Jeremy; Kullmer, Ottmar; Bromage, Timothy G.; Schrenk, Friedemann

    2011-01-01

    Neanderthal diets are reported to be based mainly on the consumption of large and medium sized herbivores, while the exploitation of other food types including plants has also been demonstrated. Though some studies conclude that early Homo sapiens were active hunters, the analyses of faunal assemblages, stone tool technologies and stable isotopic studies indicate that they exploited broader dietary resources than Neanderthals. Whereas previous studies assume taxon-specific dietary specializations, we suggest here that the diet of both Neanderthals and early Homo sapiens is determined by ecological conditions. We analyzed molar wear patterns using occlusal fingerprint analysis derived from optical 3D topometry. Molar macrowear accumulates during the lifespan of an individual and thus reflects diet over long periods. Neanderthal and early Homo sapiens maxillary molar macrowear indicates strong eco-geographic dietary variation independent of taxonomic affinities. Based on comparisons with modern hunter-gatherer populations with known diets, Neanderthals as well as early Homo sapiens show high dietary variability in Mediterranean evergreen habitats but a more restricted diet in upper latitude steppe/coniferous forest environments, suggesting a significant consumption of high protein meat resources. PMID:21445243

  17. A Neanderthal lower molar from Stajnia Cave, Poland.

    PubMed

    D?browski, P; Nowaczewska, W; Stringer, C B; Compton, T; Kruszy?ski, R; Nadachowski, A; Stefaniak, K; Urbanowski, M

    2013-04-01

    The primary aim of this study was to conduct a taxonomic assessment of the second of three isolated human teeth found in the Stajnia Cave (north of the Carpathians, Poland) in 2008. The specimen was located near a human tooth (S5000), which was identified by Urbanowski et al. (2010) as a Neanderthal permanent upper molar. Both of these teeth were excavated from the D2 layer, which belongs to the D stratigraphic complex comprising the archaeological assemblage associated with the Micoquian tradition. An Ursus spelaeus bone and Mammuthus primigenius tooth that were also excavated from the D2 layer were dated to >49,000 years BP (by AMS (14)C) and 52.9 ka BP (by U-Th), respectively. The sediment overlying stratigraphic complex D was dated to 45.9 ka BP by the OSL method. The S4300 tooth is a lower first or second permanent molar belonging to an individual other than that who once possessed the S5000 tooth. The S4300 tooth exhibits a combination of traits typical of Neanderthal lower molars, including a mid-trigonid crest, large anterior fovea, taurodontism and subvertical grooves on the interproximal face, indicating that this tooth belonged to a Neanderthal individual. The S4300 tooth from Stajnia Cave is one of the oldest human remains found in Poland. PMID:23415376

  18. Characteristics of 351 supernumerary molar teeth In Turkish population

    PubMed Central

    Kara, Muhammed ?.; Ay, Sinan; Bereket, Cihan; ?ener, ?smail; Blbl, Mehmet; Ezirganl?, ?eref; Polat, Hidayet B.

    2012-01-01

    Objective: The aim of the present study was to evaluate the demographic profile of supernumerary molar (SM) teeth in people in various regions of Turkey. Study Design: A retrospective analysis was carried out on an initial sample of 104,902 subjects drawn from the ortopantographics files from 10 clinics in 7 Turkish cities with documentation of demographic data, the presence of SM teeth, their location, eruption, morphology, and position within the arch. In one region associated pathologies and treatments were also evaluated. Results: Three hundred fifty-one SMs were detected in 288 patients, constituting 0.33% of the study subjects, with a greater frequency in females (56.4%). SMs were found more frequently in the maxilla (87.7%) than in the mandible, and distomolars (62.9%) were more common than paramolars. The SMs encountered were mostly of conical shape (45.7%), impacted (81.1%), and in a vertical position (52.1). The 33% of SM teeth were related to impacted molar teeth. Conclusion: The most common complication involving these teeth was soft tissue irritation. Demographic data from such specific extensive studies are crucial for improved diagnosis of SM teeth. Early detection allows for measures against complications and more successful therapy. Key words:Supernumerary molars, distomolar, paramolar, prevalence. PMID:22143736

  19. GENERAL: Low-temperature heat capacities and standard molar enthalpy of formation of N-methylnorephedrine C11H17NO(s)

    NASA Astrophysics Data System (ADS)

    Di, You-Ying; Wang, Da-Qi; Shi, Quan; Tan, Zhi-Cheng

    2008-08-01

    This paper reports that low-temperature heat capacities of N-methylnorephedrine C11H17NO(s) have been measured by a precision automated adiabatic calorimeter over the temperature range from T = 78 K to T = 400K. A solid to liquid phase transition of the compound was found in the heat capacity curve in the temperature range of T = 342-364 K. The peak temperature, molar enthalpy and entropy of fusion of the substance were determined. The experimental values of the molar heat capacities in the temperature regions of T = 78-342 K and T = 364-400 K were fitted to two polynomial equations of heat capacities with the reduced temperatures by least squares method. The smoothed molar heat capacities and thermodynamic functions of N-methylnorephedrine C11H17NO(s) relative to the standard reference temperature 298.15 K were calculated based on the fitted polynomials and tabulated with an interval of 5 K. The constant-volume energy of combustion of the compound at T = 298.15K was measured by means of an isoperibol precision oxygen-bomb combustion calorimeter. The standard molar enthalpy of combustion of the sample was calculated. The standard molar enthalpy of formation of the compound was determined from the combustion enthalpy and other auxiliary thermodynamic data through a Hess thermochemical cycle.

  20. Hypercementosis and concrescence of maxillary second molar with third molar: a case report and review of literature.

    PubMed

    Mohan, Bhavya

    2014-06-01

    Concrescence signifies a rare developmental alteration, most commonly in maxillary molars,where two fully formed teeth with separate root canal structures are fused with cementum. Clinical detection is difficult due to lack of enamel involvement and radiographic detection may be challenging, as two dimensional images may be misdiagnosed as overlap, superimposition or close proximity of roots. Such a developmental anomaly can influence treatment outcomes for extraction, endodontic, periodontic, prosthodontic and orthodontic treatment. Legal complications could arise due to unexpected difficulties following treatment. Awareness of occurrence, incidence and post treatment implications of such anomalies is paramount for both the patient and clinician's benefit. This article discusses a case report of concrescence between two maxillary molar teeth and its management. PMID:24984682

  1. Relationship between bulk and local chemistries (hideout return) in molar ratio control and non molar ratio control

    SciTech Connect

    Sawochka, S.G.; Choi, S.S.; Fruzzetti, K.

    1996-12-31

    Analysis of PWR steam generator hideout return data employing EPRI`s MLTLTEQ codes yielded wide variations in predicted crevice solution pH. Reliable correlations of pH and hideout return and operating molar ratios of sodium to chloride and sodium to chloride plus sulfate were not present. Crevices were predicted to contain concentrated solutions of sodium chloride and potassium chloride during operation.

  2. How often do asymptomatic, disease-free third molars need to be removed?

    PubMed

    Vent, Irja

    2012-09-01

    The preventive removal of third molars (M3s) should be based on evidence. To optimize the timing of removal of M3s, it is essential to predict the eruption of the tooth and, even more importantly, to recognize beforehand which teeth will become involved in pathologic conditions later in life. The first aim of this review was to determine how well physicians currently can predict the eruption of an M3. The second aim was to review how frequently impacted M3s are removed. The third aim was to summarize the indications for preventive removals as presented in the evidence-based Current Care Guideline for the management of M3s in Finland. The prediction of eruption can be made at accuracies from 80% to 97%. In addition, the decrease in the number of M3s is very rapid, with only 31% remaining at 38 years of age. According to the Current Care Guideline, preventive removals at a young age are justified for 3 groups of teeth in the mandible: partially impacted teeth in the horizontal position, partially erupted teeth in the vertical position, and incomplete roots growing close to the mandibular canal. In conclusion, one fourth of retained and disease-free M3s need to be removed preventively at a young age, whereas the rest should be treated according to signs and symptoms. PMID:22916699

  3. Molar Mass and Second Virial Coefficient of Polyethylene Glycol by Vapor Pressure Osmometry

    ERIC Educational Resources Information Center

    Schwinefus, Jeffrey J.; Checkal, Caleb; Saksa, Brian; Baka, Nadia; Modi, Kalpit; Rivera, Carlos

    2015-01-01

    In this laboratory experiment, students determine the number-average molar masses and second virial coefficients of polyethylene glycol (PEG) polymers ranging in molar mass from 200 to 1500 g mol[superscript -1] using vapor pressure osmometry (VPO). Students assess VPO in relation to accurate molar mass calculations of PEG polymers. Additionally,

  4. Molar Mass and Second Virial Coefficient of Polyethylene Glycol by Vapor Pressure Osmometry

    ERIC Educational Resources Information Center

    Schwinefus, Jeffrey J.; Checkal, Caleb; Saksa, Brian; Baka, Nadia; Modi, Kalpit; Rivera, Carlos

    2015-01-01

    In this laboratory experiment, students determine the number-average molar masses and second virial coefficients of polyethylene glycol (PEG) polymers ranging in molar mass from 200 to 1500 g mol[superscript -1] using vapor pressure osmometry (VPO). Students assess VPO in relation to accurate molar mass calculations of PEG polymers. Additionally,…

  5. Relationship between mandibular condyle and angle fractures and the presence of mandibular third molars

    PubMed Central

    Mah, Deuk-Hyun; Moon, Seong-Yong; Oh, Ji-Su; You, Jae-Seek

    2015-01-01

    Objectives We retrospectively evaluated the impact of mandibular third molars on the occurrence of angle and condyle fractures. Materials and Methods This was a retrospective investigation using patient records and radiographs. The sample set consisted of 440 patients with mandibular fractures. Eruption space, depth and angulation of the third molar were measured. Results Of the 144 angle fracture patients, 130 patients had third molars and 14 patients did not. The ratio of angle fractures when a third molar was present (1.26 : 1) was greater than when no third molar was present (0.19 : 1; odds ratio, 6.58; P<0.001). Of the 141 condyle fractures patients, the third molar was present in 84 patients and absent in 57 patients. The ratio of condyle fractures when a third molar was present (0.56 : 1) was lower than when no third molar was present (1.90 : 1; odds ratio, 0.30; P<0.001). Conclusion The increased ratio of angle fractures with third molars and the ratio of condyle fractures without a third molar were statistically significant. The occurrence of angle and condyle fractures was more affected by the continuity of the cortical bone at the angle than by the depth of a third molar. These results demonstrate that a third molar can be a determining factor in angle and condyle fractures. PMID:25741462

  6. Sub-10-Minute Characterization of an Ultrahigh Molar Mass Polymer by Multi-detector Hydrodynamic Chromatography

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Molar mass averages, distributions, and architectural information of polymers are routinely obtained using size-exclusion chromatography (SEC). It has previously been shown that ultrahigh molar mass polymers may experience degradation during SEC analysis, leading to inaccurate molar mass averages a...

  7. Partial (focal) seizure

    MedlinePLUS

    ... Jacksonian seizure; Seizure - partial (focal); Temporal lobe seizure; Epilepsy - partial seizures ... Abou-Khalil BW, Gallagher MJ, Macdonald RL. Epilepsies. In: Daroff RB, ... 6th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 67. ...

  8. Partial tooth gear bearings

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    2010-01-01

    A partial gear bearing including an upper half, comprising peak partial teeth, and a lower, or bottom, half, comprising valley partial teeth. The upper half also has an integrated roller section between each of the peak partial teeth with a radius equal to the gear pitch radius of the radially outwardly extending peak partial teeth. Conversely, the lower half has an integrated roller section between each of the valley half teeth with a radius also equal to the gear pitch radius of the peak partial teeth. The valley partial teeth extend radially inwardly from its roller section. The peak and valley partial teeth are exactly out of phase with each other, as are the roller sections of the upper and lower halves. Essentially, the end roller bearing of the typical gear bearing has been integrated into the normal gear tooth pattern.

  9. A method for estimating both the solubility parameters and molar volumes of liquids

    NASA Technical Reports Server (NTRS)

    Fedors, R. F.

    1974-01-01

    Development of an indirect method of estimating the solubility parameter of high molecular weight polymers. The proposed method of estimating the solubility parameter, like Small's method, is based on group additive constants, but is believed to be superior to Small's method for two reasons: (1) the contribution of a much larger number of functional groups have been evaluated, and (2) the method requires only a knowledge of structural formula of the compound.

  10. Initial Clinical Experience With the Strut-Adjusted Volume Implant (SAVI) Breast Brachytherapy Device for Accelerated Partial-Breast Irradiation (APBI): First 100 Patients With More Than 1 Year of Follow-Up

    SciTech Connect

    Yashar, Catheryn M.; Scanderbeg, Daniel; Kuske, Robert; Wallace, Anne; Zannis, Victor; Blair, Sarah; Grade, Emily; Swenson, Virginia H.; Quiet, Coral

    2011-07-01

    Purpose: The Strut-Adjusted Volume Implant (SAVI; Cianna Medical, Aliso Viejo, CA) is a multichannel single-entry brachytherapy device designed to allow dose modulation to minimize normal tissue dose while simultaneously maximizing target coverage. This is the first report on the initial 102 patients with nearly 2 years of median follow-up. Methods and Materials: One hundred two patients were treated at two institutions. Data were collected on eligibility and dosimetry and followed for toxicity and recurrence. Results: The median follow-up is 21 months. Overall dosimetry is outstanding (median percent of target volume receiving 90% of the prescription dose was 95.9%, volume of target receiving 150% of the prescription dose was 27.8 mL, and volume of target receiving 200% of the prescription dose was 14.0 cm{sup 3}). No devices were pulled prior to treatment completion. For patients with a skin bridge of less than 7 mm, the maximum median skin dose was 280 cGy (median percent of target volume receiving 90% of the prescription dose was 95.2%, volume of target receiving 150% of the prescription dose was 25.8 cm{sup 3} and volume of target receiving 200% of the prescription dose was 12.7 mL). For patients with both chest wall and skin of less than 7 mm, the maximum median lung dose was 205 cGy with simultaneous skin dose of 272 cGy. The rate of telangiectasia was 1.9%. Grade 1 hyperpigmentation developed in 10 patients (9.8%) and Grade 2 fibrosis in 2 patients (1.9%). There were 2 symptomatic seromas and 2 cases of asymptomatic fat necrosis (1.9%). Of the patients, 27% were not eligible for MammoSite balloon brachytherapy (Hologic, Inc., Marlborough, MA) and 5% were not eligible for any balloon brachytherapy. The recurrence rate was 1%. Conclusions: The SAVI appears to safely allow an increase in eligibility for APBI over balloon brachytherapy or three-dimensional conformal radiation, highlighting the outstanding device flexibility to maximize the target dose and minimize the normal tissue dose. The device was well tolerated by patients.

  11. p57KIP2 immunohistochemistry in early molar pregnancies: emphasis on its complementary role in the differential diagnosis of hydropic abortuses.

    PubMed

    Merchant, Shakil H; Amin, Mitual B; Viswanatha, David S; Malhotra, Rajwant K; Moehlenkamp, Cynthia; Joste, Nancy E

    2005-02-01

    Morphologic examination still forms the main diagnostic tool in the differential diagnosis of molar pregnancies. However, the criteria are subjective and show considerable interobserver variability among pathologists. Once a diagnosis of molar pregnancy is made, DNA ploidy studies help to differentiate a triploid partial mole from diploid complete mole (CM). However, with earlier diagnosis and therapeutic evacuation of molar pregnancies, the differentiation of molar pregnancies from early nonmolar placentation is becoming increasingly difficult. The p57(KIP2) gene ( CDKN1C ) is strongly paternally imprinted and expressed from the maternal allele. Because CM lacks a maternal genome, p57(KIP2) immunostaining is correspondingly absent, whereas hydropic abortuses and partial mole show positive staining. We compared the use of p57(KIP2) staining in the differential diagnosis of 68 morphologically challenging cases of early first-trimester hydropic placentas. Diagnosis based on p57(KIP2) staining was compared with the original diagnosis based on morphology and DNA ploidy analysis. Concordant results were obtained in 65 of 68 cases studied. In 2 of 3 cases with a discordant diagnosis, microsatellite DNA genotyping analysis agreed with the results of p57(KIP2) staining, confirming that positive p57(KIP2) staining is a highly sensitive and specific marker for excluding CM in this setting. In addition, p57(KIP2) staining has the advantage of differentiating hydropic abortuses from CMs, a distinction not made by ploidy analysis. p57(KIP2) staining can be used in concert with ploidy studies to refine the diagnosis of early molar pregnancies. PMID:15754295

  12. Cameriere's third molar maturity index in assessing age of majority.

    PubMed

    Gali?, Ivan; Lauc, Tomislav; Brki?, Hrvoje; Vodanovi?, Marin; Gali?, Elizabeta; Biazevic, Maria Gabriela Haye; Brakus, Ivan; Badrov, Jozo; Cameriere, Roberto

    2015-07-01

    Estimation of chronological age of an individual is one of the main challenges in forensic science. Legally to be able to treat a person as a minor or an adult, it is necessary to determine whether their age of majority (if they are older or younger than 18, in most countries). Methods for estimating age are especially important when an individual in question lacks personal documents or other means of identification. As the dental age differs in various populations, the aim of this study was to evaluate applicability of third molar method for assessing age of majority in Croatia. Cameriere's third molar maturity index (I3M) value of 0.08, measured by the open apices of the teeth, was verified in sample of 1336 panoramic images aged between 14 and 23 years. Chronological age gradually decreased as I3M increased in both genders. Males showed statistically significant advanced maturation when I3M was between 0.0 and 0.3 value. The results indicate that the sensitivity of the test for 0.08 value was 84.3% (95%CI 80.6%, 87.5%) for females and 91.2% (95%CI 88.7%, 93.1) for males. Specificity was 95.4% (95%CI 92.5%, 97.5%) and 91.9% (95%CI 88.8%, 94.3%). The proportions of accurately classified males were 88.8% and that of females 91.5%. The estimated post-test probabilities, of individuals, in other word the probability that a Croatian individual with an I3M<0.08 is 18 years or older is 94.5% for females, and 96.5% for males. With high accuracy, the third molar maturity index should be used as a determinant of the age of majority in Croatia. PMID:26013667

  13. Irregular Periapical Radiopacity in Mandibular Premolars and Molars

    PubMed Central

    Warrier, S. Aravind; Vinayachandran, Divya

    2014-01-01

    Increased deposition of cementum is observed in a wide number of both benign and malignant conditions. Many cases are often diagnosed during routine examination as an incidental finding. Diagnosing correctly without confusing it with other similarly appearing lesions, thus avoiding subjecting the patient to unnecessary investigations and stress, is of prime importance. We report one such case, where the patient presented with the routine complaint of a painful tooth, during the investigation of which he was also diagnosed with hypercementosis affecting the mandibular second premolars and molars bilaterally. The literature review reveals that not many cases of hypercementosis are frequently reported. PMID:24716003

  14. Adenomatoid odontogenic tumor associated with unerupted first primary molar.

    PubMed

    Lee, Jae-Seo; Yoon, Suk-Ja; Kang, Byung-Cheol; Kim, Ok-Jun; Kim, Young-Hee

    2012-01-01

    Adenomatoid odontogenic tumors (AOTs) are an uncommon benign odontogenic tumor. Both central and peripheral forms occur. Radiographically, the central variants are comprised of a follicular type (those associated with the crown of an embedded tooth) and an extrafollicular type (those with no embedded tooth). A review of the literature showed that only 3 cases of an association between AOT and unerupted primary teeth have been published. The purpose of this paper was to report a rare case of adenomatoid odontogenic tumor associated with an unerupted primary first molar in a 7-year-old boy. PMID:23265168

  15. Peripheral facial nerve paralysis after upper third molar extraction.

    PubMed

    Cakarer, Sirmahan; Can, Taylan; Cankaya, Burak; Erdem, Mehmet Ali; Yazici, Sinem; Ayintap, Emre; Özden, Ali Veysel; Keskin, Cengizhan

    2010-11-01

    Peripheral facial nerve paralysis (PFNP) after mandibular interventions has been reported in the literature. In most cases, paralysis begins immediately after the injection of the mandibular anesthesia, and duration of facial weakness is less than 12 hours. However, there are few documented cases of PFNP after maxillary dental or surgical procedures. A variety of mechanisms have been associated to PFNP, including viral reactivation, demyelination, edema, vasospasm, and trauma. The purpose of this presentation was to report a rare case of facial paralysis that occurred after an upper third molar extraction. The cause of the PFNP and the importance of the multidisciplinary approach in the management are emphasized. PMID:21119431

  16. Restoration of Endodontically Treated Molars Using All Ceramic Endocrowns

    PubMed Central

    Carlos, Roopak Bose; Thomas Nainan, Mohan; Pradhan, Shamina; Roshni Sharma; Benjamin, Shiny; Rose, Rajani

    2013-01-01

    Clinical success of endodontically treated posterior teeth is determined by the postendodontic restoration. Several options have been proposed to restore endodontically treated teeth. Endocrowns represent a conservative and esthetic restorative alternative to full coverage crowns. The preparation consists of a circular equigingival butt-joint margin and central retention cavity into the entire pulp chamber constructing both the crown and the core as a single unit. The case reports discussed here are moderately damaged endodontically treated molars restored using all ceramic endocrowns fabricated using two different systems, namely, CAD/CAM and pressed ceramic. PMID:24455318

  17. Unilateral single-rooted primary mandibular first molar

    PubMed Central

    Chaudhari, Purva; Mallikarjuna, Rachappa; Swadas, Milan; Dave, Bhavna

    2013-01-01

    A 4-year-old boy reported food lodgement and pain in the lower left back tooth region. On examination, a deeply carious tooth with food lodgement was seen. On oral examination, numbers of teeth were found to be carious and required restorations and endodontic treatments according to radiographic evaluation. Radiograph of mandibular left first deciduous molar revealed an unusual morphology of root. It was single-rooted and presented with Vertucci's class I canal. The tooth was treated by pulpectomy followed by a stainless steel crown. All other carious teeth were treated as planned. PMID:23893279

  18. Why, what and how: caries control for erupting molars.

    PubMed

    Rogers, Helen J; Morgan, Annie G; Batley, Haris; Deery, Chris

    2015-03-01

    This article aims to update the practitioner on the various techniques and interventions available to prevent or control caries during this high-risk period. The evidence to support provision of toothbrushing advice, placement of fissure sealants and fluoride varnish application is considered, along with more novel methods. An evidence-based protocol is suggested to help the practitioner determine when further intervention is required and what action to undertake. Clinical Relevance: This article aims to reinforce the need for rigorous caries prevention in an erupting permanent molar and provides an update on the evidence behind a range of clinical techniques used for this purpose. PMID:26058229

  19. Compensation trends of the angulation of first molars: retrospective study of 1403 malocclusion cases.

    PubMed

    Su, Hong; Han, Bing; Li, Sa; Na, Bin; Ma, Wen; Xu, Tian-Min

    2014-09-01

    We investigated the compensatory trends of mesiodistal angulation of first molars in malocclusion cases. We compared differences in the angulation of first molars in different developmental stages, malocclusion classifications and skeletal patterns. The medical records and lateral cephalogrammes of 1403 malocclusion cases taken before treatment were measured to evaluate compensation of molar angulation in relation to the skeletal jaw. The cases were stratified by age, Angle classification and skeletal patterns. Differences in the mesiodistal angulation of the first molars were compared among the stratifications. We observed three main phenomena. First, angulation of the upper first molar varied significantly with age and tipped most distally in cases aged <12 years and least distally in cases aged >16 years. The lower first molar did not show such differences. Second, in Angle Class II or skeletal Class II cases, the upper first molar was the most distally tipped, the lower first molar was the most mesially tipped, and opposite angulation compensation was observed in Class III cases. Third, in high-angle cases, the upper and lower first molars were the most distally tipped, and opposite angulation compensation was observed in low-angle cases. These data suggest that the angulation of the molars compensated for various growth patterns and malocclusion types. Hence, awareness of molar angulation compensation would help to adjust occlusal relationships, control anchorage and increase the chances of long-term stability. PMID:24699185

  20. Replantation of a maxillary second molar after removal of a third molar with a dentigerous cyst: Case report and 12-month follow-up

    PubMed Central

    Pearrocha-Diago, Mara A.; Pearrocha-Oltra, David; Pearrocha-Diago, Miguel

    2014-01-01

    The aim of this study was to describe the replantation of a maxillary second right molar, which had been removed for surgical reasons in order to remove a dentigerous cyst associated with the adjacent third molar, and the cases 12-month follow-up. A 51-year-old man presented swelling in the right maxillary area. Radiographic examination showed a large radiolucency in close proximity to the third molar, suggesting a follicular cyst. The third molar was extracted and the cyst underwent curettage. The second molar had to be extracted to enable complete removal of the cyst and to achieve primary closure of the wound, which would have been impossible without repositioning the molar. With this objective, extraoral endodontic treatment was performed, the root-end was resected and prepared with ultrasonic retrotips, and root-end filling was accomplished with MTA before the molar was replanted. At the 12-month follow-up, the tooth showed no clinical signs or symptoms, probing depth was no greater than 3 mm and radiographic examination showed no evidence of root resorption or periapical lesion. Key words:Replantation, maxillary molar, follicular cyst, dentigerous cyst. PMID:24790721

  1. Theory of chromatography of partially cyclic polymers: Tadpole-type and manacle-type macromolecules.

    PubMed

    Vakhrushev, Andrey V; Gorbunov, Alexei A

    2016-02-12

    A theory of chromatography is developed for partially cyclic polymers of tadpole- and manacle-shaped topological structures. We present exact equations for the distribution coefficient K at different adsorption interactions; simpler approximate formulae are also derived, relevant to the conditions of size-exclusion, adsorption, and critical chromatography. Theoretical chromatograms of heterogeneous partially cyclic polymers are simulated, and conditions for good separation by topology are predicted. According to the theory, an effective SEC-radius of tadpoles and manacles is mostly determined by the molar mass M, and by the linear-cyclic composition. In the interactive chromatography, the effect of molecular topology on the retention becomes significant. At the critical interaction point, partial dependences K(Mlin) and K(Mring) are qualitatively different: while being almost independent of Mlin, K increases with Mring. This behavior could be realized in critical chromatography-for separation of partially cyclic polymers by the number and molar mass of cyclic elements. PMID:26803439

  2. A geometric morphometric analysis of hominin upper first molar shape.

    PubMed

    Gmez-Robles, A; Martinn-Torres, M; Bermdez de Castro, J M; Margvelashvili, A; Bastir, M; Arsuaga, J L; Prez-Prez, A; Estebaranz, F; Martnez, L M

    2007-09-01

    Recent studies have revealed interesting differences in upper first molar morphology across the hominin fossil record, particularly significant between H. sapiens and H. neanderthalensis. Usually these analyses have been performed by means of classic morphometric methods, including the measurement of relative cusp areas or the angles defined between cusps. Although these studies have provided valuable information for the morphological characterization of some hominin species, we believe that the analysis of this particular tooth could be more conclusive for taxonomic assignment. In this study, we have applied geometric morphometric methods to explore the morphological variability of the upper first molar (M(1)) across the human fossil record. Our emphasis focuses on the study of the phenetic relationships among the European middle Pleistocene populations (designated as H. heidelbergensis) with H. neanderthalensis and H. sapiens, but the inclusion of Australopithecus and early Homo specimens has helped us to assess the polarity of the observed traits. H. neanderthalensis presents a unique morphology characterized by a relatively distal displacement of the lingual cusps and protrusion in the external outline of a large and bulging hypocone. This morphology can be found in a less pronounced degree in the European early and middle Pleistocene populations, and reaches its maximum expression with the H. neanderthalensis lineage. In contrast, modern humans retain the primitive morphology with a square occlusal polygon associated with a round external outline. PMID:17599390

  3. Nanoparticle counting: towards accurate determination of the molar concentration.

    PubMed

    Shang, Jing; Gao, Xiaohu

    2014-11-01

    Innovations in nanotechnology have brought tremendous opportunities for the advancement of many research frontiers, ranging from electronics, photonics, energy, to medicine. To maximize the benefits of nano-scaled materials in different devices and systems, precise control of their concentration is a prerequisite. While concentrations of nanoparticles have been provided in other forms (e.g., mass), accurate determination of molar concentration, arguably the most useful one for chemical reactions and applications, has been a major challenge (especially for nanoparticles smaller than 30 nm). Towards this significant yet chronic problem, a variety of strategies are currently under development. Most of these strategies are applicable to a specialized group of nanoparticles due to their restrictions on the composition and size range of nanoparticles. As research and uses of nanomaterials are being explored in an unprecedented speed, it is necessary to develop universal strategies that are easy to use and are compatible with nanoparticles of different sizes, compositions, and shapes. This review outlines the theories and applications of current strategies to measure nanoparticle molar concentration, discusses the advantages and limitations of these methods, and provides insights into future directions. PMID:25099190

  4. Solvent-mediated molar conductivity of protic ionic liquids.

    PubMed

    Thawarkar, Sachin; Khupse, Nageshwar D; Kumar, Anil

    2015-01-01

    The molar conductivity, ?m, of protic ionic liquids (PILs) in molecular solvents is measured at 298.15 K. The decrease in the ?m values of PILs is observed with an increase in the concentration of PILs. The limiting molar conductivities, ?m(0), were obtained for each PIL in different molecular solvents using a least squares method. The ?m(0) data for PILs were correlated with the structural aspects of PILs and solvent properties. The polar protic solvents show poor ionic association as compared to the polar aprotic solvents, which is discussed on the basis of the hydrogen bond donating (HBD) ability of solvents and PILs. The alkyl chain substitution of anions plays a significant role in the ionic association of the PILs. The diffusion coefficient D(0) and the transport number t were determined, which were consistent with the ?m(0) values of PILs in water. The ?m(0) and D(0) values are dependent on the hydrodynamic radius of anions of these ionic liquids. The extent of ionic association for each PIL was discussed using temperature dependent ?m data for aqueous PIL systems in terms of the Walden plot. PMID:25406387

  5. Effect of the suture technique on postoperative pain, swelling and trismus after removal of lower third molars: A randomized clinical trial

    PubMed Central

    Gmez-Santos, Laila; Snchez-Torres, Alba; Herrez-Vilas, Jos-Mara

    2015-01-01

    Background To evaluate the intensity of pain, swelling and trismus after the removal of impacted lower third molars comparing two different suture techniques of the triangular flap: the complete suture of the distal incision and relieving incision and the partial suture with only one suture knot for closure of the corner of the flap and the closure of the distal incision, without suturing the relieving incision. Material and Methods A prospective, randomized, crossover clinical trial was conducted in 40 patients aged from 18 to 45 years who underwent surgical extraction of impacted lower third molars at the Department of Oral Surgery in the Odontological Hospital of the University of Barcelona during the year 2011. Patients were randomly divided in 2 groups. Two different techniques (hermetical closure and partial closure of the wound) were performed separated by a one month washout period in each patient. Postoperative pain, swelling and trismus were evaluated prior to the surgical procedure and also at 2 and 7 days post operatively. Results No statistically significant differences were observed for pain (p<0.06), trismus (p<0.71) and swelling (p<0.05) between the test and the control group. However, the values of the three parameters related to the test group were lower than those for the control group. Conclusions Partial closure of the flap without suturing the relieving incision after surgical extraction of lower third molars reduces operating time and it does not produce any postoperative complications compared with complete closure of the wound. Key words: Third molar, surgical flaps, suture techniques, postoperative pain, swelling, trismus. PMID:25662551

  6. Long-term clinical failure rate of molar tubes bonded with a self-etching primer.

    PubMed

    Pandis, Nikolaos; Christensen, Lars; Eliades, Theodore

    2005-11-01

    The purpose of this study was to assess the long-term in vivo failure rate of tubes bonded to first and second molars with a self-etching primer (SEF). A total of 810 molar tubes (414 first molar and 396 second molar) were bonded on 135 patients (56 male, 79 female; mean age 14 years) with the 3M Transbond Plus Self Etching Primer. The first-time failures of the tubes were recorded for a mean period of 26 months (range 23-29 months). Failure rates per jaw (maxilla-mandible), tooth (first and second molar), and quadrant (left, right) were analyzed with the chi(2) at alpha = 0.05 level of significance. Significant differences were found in the failure rate between first and second molars (9.66% vs 20%, respectively) as well as maxillary and mandibular molars (7.5% vs 21%, respectively). The combined, total failure rate for first and second molars was 14.80%. No difference was found between male and female failure rates for the molar tubes. First-molar tubes bonded with an SEF may show failure rates comparable with those reported in the literature for tubes bonded with conventional acid etching. PMID:16448245

  7. Patterns of bilateral agenesis of maxillary third molars and agenesis of other teeth.

    PubMed

    Sanpei, Sugako; Ishida, Rieko; Sanpei, Shinya; Endo, Saori; Tanaka, Satoshi; Endo, Toshiya; Sekimoto, Tsuneo

    2016-01-01

    The purpose of this study was to investigate the patterns of bilateral agenesis of maxillary third molars and other tooth agenesis in Japanese orthodontic patients. A group of 262 subjects with bilateral agenesis of maxillary third molars (group A) was divided into three subgroups: group 1A consisting of 114 subjects without agenesis of mandibular third molars; group 2A, 31 subjects with unilateral agenesis of mandibular third molars; and group 3A, 117 subjects with agenesis of all third molars. As controls, 926 other subjects without third molar agenesis were selected (group C). Panoramic radiographs were mainly used to examine for tooth agenesis. The Chi square test and odds ratio were used to make statistical comparisons. The prevalence rates of agenesis of maxillary lateral incisors, mandibular incisors and maxillary and mandibular second premolars, and bilateral agenesis of maxillary lateral incisors and second premolars were significantly higher in any one of the third molar agenesis groups than in the control group. Characteristically, no significant increase in occurrence of bilateral agenesis of mandibular second premolars was demonstrated by the subjects with bilateral agenesis of maxillary third molars. Irrespective of whether unilateral or bilateral agenesis of mandibular third molars is present or not, the Japanese orthodontic patients with bilateral agenesis of maxillary third molars exhibited a significantly increased occurrence of unilateral or bilateral agenesis of maxillary lateral incisors, mandibular incisors and maxillary and mandibular second premolars, except for bilateral agenesis of mandibular incisors and second premolars. PMID:25636272

  8. Lattice potential energy and standard molar enthalpy in the formation of 1dodecylamine hydrobromide (1-C12H25NH3Br)(s)

    NASA Astrophysics Data System (ADS)

    Liu, Yu-Pu; Di, You-Ying; Dan, Wen-Yan; He, Dong-Hua; Kong, Yu-Xia; Yang, Wei-Wei

    2011-02-01

    This paper reports that 1-dodecylamine hydrobromide (1-C12H25NH3Br)(s) has been synthesized using the liquid phase reaction method. The lattice potential energy of the compound 1-C12H25NH3Br and the ionic volume and radius of the 1-C12H25NH3+ cation are obtained from the crystallographic data and other auxiliary thermodynamic data. The constant-volume energy of combustion of 1-C12H25NH3Br(s) is measured to be ?cUmo(1-C12H25NH3Br, s) = -(7369.033.28) kJmol-1 by means of an RBC-II precision rotating-bomb combustion calorimeter at T = (298.150.001) K. The standard molar enthalpy of combustion of the compound is derived to be ?cHmo(1-C12H25NH3Br, s) = -(7384.523.28) kJmol-1 from the constant-volume energy of combustion. The standard molar enthalpy of formation of the compound is calculated to be ?fHmo(1-C12H25NH3Br, s)=-(1317.863.67) kJmol-1 from the standard molar enthalpy of combustion of the title compound and other auxiliary thermodynamic quantities through a thermochemical cycle.

  9. The interplay of Graves’ disease and twin molar pregnancy

    PubMed Central

    Barrera, Jerome Rebollos; Sandoval, Mark Anthony Santiago; Quiwa, Leslie Quizon; Paz-Pacheco, Elizabeth

    2013-01-01

    Twin molar pregnancy with coexistent viable fetus in a patient with Graves’ disease is a rare entity. The patient is a 37-year-old woman who was hospitalised owing to persistent vomiting and vaginal bleeding. The pregnancy test was positive and the pelvic ultrasound disclosed twin gestation of complete mole and a coexistent viable 12-week fetus. β-Human chorionic gonadotropin (β-HCG) and free thyroid hormones were both elevated. The patient was also a diagnosed case of Graves’ disease prior to this pregnancy. Given the risks for perinatal complications, the patient was offered early termination of pregnancy. She, however, decided to continue her pregnancy and control the hyperthyroidism with an antithyroid drug (ATD). A week after her discharge from the hospital, she had spontaneous abortion and the histopathology of the abortus revealed complete hydatidiform mole and a 13-week fetus. PMID:23436894

  10. Periodontal regeneration of transplanted rat molars after cryopreservation.

    PubMed

    Kawasaki, Naoko; Hamamoto, Yoshioki; Nakajima, Tamio; Irie, Kazuharu; Ozawa, Hidehiro

    2004-01-01

    The effects of cryopreservation on periodontal regeneration of transplanted rat molars were investigated histologically and histochemically in rats. Bilateral first and second maxillary molars of 4-week-old Wistar rats were gently extracted and transplanted into the abdominal subcutaneous connective tissue immediately or after cryopreservation in liquid nitrogen overnight. Donor teeth were slowly frozen by a rate-controlling freezer (program freezer) using 5% dimethylsulfoxide (DMSO) and 6% hydroxyethyl starch (HES) as cryoprotectants. One-four weeks after transplantation, they were carefully excised with the surrounding tissues. Regeneration of acellular cementum, periodontal ligament, and alveolar bone were observed 2 weeks after immediate transplantation. The pulp was repaired by the ingrowth of granulation tissue from the root apex followed by the formation of calcified tissue. The regenerated periodontal ligament was positive for alkaline phosphatase (ALP). Small or mononuclear tartrate resistant acid phosphatase (TRAP) positive cells were scattered on the newly formed alveolar bone and on the hard tissue in the pulp, but there was no external or internal progressive root resorption at 4 weeks. Cryopreserved teeth had acellular cementum with a rough surface at 1 week, but with the increase of cementoblasts and the appearance of periodontal ligament and alveolar bone, the surface became smooth at 3 weeks. Epithelial rests of Malassez (ERM) also revived. After regeneration of the periodontal tissues at 4 weeks, there was no evidence of root resorption. Although the process proceeded slowly, the cryopreserved teeth showed the periodontal regeneration substantially similar to that of the immediately transplanted teeth without progressive root resorption, indicating that they could be applicable for clinical use. PMID:14693198

  11. A rare case of impacted supernumerary premolar causing resorption of mandibular first molar.

    PubMed

    Murali, R V; Gnanashanmugam, K; Rajasekar, L; Kularashmi, B S; Saravanan, B

    2015-04-01

    The management of patients with pain in today's general practice has become a major concern and sometimes this pain is related to some rare causes. A male patient aged 26 years reported with pain in the lower left molar region (36) and then an intra-oral periapical radiograph (IOPA), and orthopantomograph was taken. IOPA revealed the presence of supernumerary premolar causing pressure and root resorption of 36. Also, there was missing 21 and proximal decay in 11. Eleven was treated endodontically, and then bridge was done in relation to 11, 21 and 22. Lower anterior crowding was also present. The treatment plan was to extract 36 followed by orthodontic extrusion of the supernumerary premolar and also the correction of lower anterior crowding. Hidden approach (lingual orthodontics) was used as the patient was insisting upon the braces not being seen outside during the course of the treatment. Later all ceramic bridge was done in relation to 11, 21 and 22. Orthodontic tooth extrusion techniques offer excellent treatment options for Partially Impacted tooth. It is a well-documented clinical method for extruding sound tooth material from within the alveolar socket by light forces. The use of lingual technique for forced eruption enhance acceptance of orthodontic treatment by adults. The treatment of a young adult patient illustrates the importance of treatment planning from one discipline to another, communication among team members and the benefits of working together in an interdisciplinary approach. PMID:26015740

  12. Fertility preserving treatment in a nulliparous with a molar pregnancy: a case report.

    PubMed

    Filipescu, George Alexandru; Boiangiu, Andreea Gratiana; Clim, Nicoleta; Andrei, Florin

    2014-01-01

    Hydatidiform mole represents an abnormal form of conception that occurs in about one in 500-1000 pregnancies. It is a subtype of gestational trophoblastic disease. Hydatidiform moles should be regarded as premalignant lesions because 15-20% of complete hydatidiform moles (CHMs) and 1% of partial hydatidiform moles (PHMs) undergo malignant transformation into invasive moles, choriocarcinomas, or, in rare cases, placental-site trophoblastic tumors (PSTTs). We will illustrate the case of a 26-year-old nulliparous with a seven weeks amenorrhea, positive immunological pregnancy test, a ?-HCG value of 136 000 mIUmL and minor vaginal bleeding. The ultrasonographic examination showed an enlarged endometrium with adjacent hyperechoic material containing tiny anechoic spaces and an anembryonic pregnancy, distended endometrial cavity containing innumerable, variably sized anechoic cysts with intervening hyperechoic material ("snowstorm" appearance). The CT showed a uterine mass measuring 8911167 mm, inhomogeneous density, proliferative-infiltrative endocavitary tissue without exceeding the peritoneal serosa, and a few pulmonary micronodules with not certain origin on the left inferior lobe. In this case, due to the large infiltrative uterine mass, the risk of severe bleeding after curettage and the possibility of a necessity hysterectomy, we decided to apply first of all the Methotrexate protocol for molar pregnancy. PMID:24970000

  13. Indirect pulp therapy in a symptomatic mature molar using calcium enriched mixture cement.

    PubMed

    Torabzadeh, Hassan; Asgary, Saeed

    2013-01-01

    Dental pulp has the ability of repair/regeneration. Indirect pulp therapy (IPT) is recommended for pulp preservation in asymptomatic teeth with extremely deep caries as well as teeth with clinical symptoms of reversible pulpitis. In this case study, we performed IPT with calcium enriched mixture (CEM) cement on a symptomatic permanent molar. After clinical/radiographic examinations the tooth was diagnosed with irreversible pulpitis and associated apical periodontitis. IPT involved partial caries removal, the placement of CEM cement pulp cap and overlying adhesive permanent restoration. At the 1 week follow-up, patient's spontaneous symptoms had resolved. One-year follow-up demonstrated pulp vitality, clinical function, as well as the absence of pain/tenderness to percussion/palpation/cold sensitivity tests; periapical radiograph showed a healing periradicular lesion with newly formed bone, that is normal pulp with normal periodontium. These favorable results indicate that IPT/CEM may be a good treatment option in comparison to endodontic treatment in young patients. IPT of deep-caries lesion is an easier, more practical and valuable treatment plan than complete caries removal. PMID:23349584

  14. Age estimation using development of third molars in South Indian population: A radiological study

    PubMed Central

    Priyadharshini, K. Indra; Idiculla, Jose Joy; Sivapathasundaram, B.; Mohanbabu, V.; Augustine, Dominic; Patil, Shankargouda

    2015-01-01

    Aim: To assess the estimation of chronological age based on the stages of third molar development following the eight stages (A–H) method of Demirjian et al. in Chennai population of South India. Materials and Methods: A sample consisting of 848 individuals (471 males and 377 females) aged between 14 and 30 years was randomly selected for the clinical evaluation and 323 orthopantomograms with clinically missing third molars were taken for radiological evaluation using Demirjian's method from a Chennai population of known chronological age and sex. Statistical analysis was performed using Pearson's Chi-square test and mean values were compared between the study groups using t-test or analysis of variance (ANOVA) followed by Tukey's highly significant difference (HSD). In the present study, P < 0.05 was considered as the level of significance. Results: The results showed that the mean age of having clinically completely erupted maxillary third molars was 22.41 years in male subjects and 23.81 years in female subjects and that of mandibular third molars was 21.49 years in male subjects and 23.34 years in female subjects. Mandibular third molars were clinically missing more often in females than in males. Eruption of mandibular third molars was generally ahead of the emergence of maxillary third molars into the oral cavity. Third molar development between male and female subjects showed statistically significant differences at calcification stage F and stage G in maxillary third molars and stage F in mandibular third molars (P < 0.05). Conclusion: There are differences indicating that maxillary and mandibular third molar eruption reached Demirjian's formation stages earlier in males than in females. It is suggested that in future studies, to increase the accuracy of age determination, indications of sexual maturity and ossification should also be evaluated in addition to third molar mineralization. PMID:25984465

  15. Three-rooted mandibular first primary molar: Report of three cases

    PubMed Central

    Gupta, Shilpi; Nagaveni, N. B.; Chandranee, N. J.

    2012-01-01

    Accessory root formation in primary teeth is an uncommon finding. An awareness and understanding of the presence of additional roots and unusual root canal morphology is essential as it determines the successful outcome of the endodontic treatment. This paper presents three case reports on the presence of three-rooted mandibular first primary molar (primary three-rooted mandibular left first molar and bilateral mandibular first molar). PMID:22629056

  16. Excess properties for 1-butanethiol + heptane, + cyclohexane, + benzene, and + toluene. 2. Excess molar enthalpies at 283.15, 298.15, and 333.15 K

    SciTech Connect

    Allred, G.C.; Beets, J.W.; Parrish, W.R.

    1995-09-01

    Thiols (mercaptans) are industrially important because of their occurrence in petroleum, their use as chemical intermediates, and their involvement in environmental problems. Excess molar enthalpies of binary mixtures of 1-butanethiol + heptane, + cyclohexane, + benzene, or + toluene have been determined at 283.15, 298.15, 333.15 K with a flow mixing calorimeter, and at 283.15 and 298.15 K with a titration calorimeter. Partial molar enthalpies have been derived from the titration calorimetric results. Where results were obtained by both methods, they were combined to obtain the best estimate of excess enthalpy for all compositions. Equimolar excess enthalpies for 1-butanethiol + heptane or + cyclohexane are endothermic and are comparable to the equimolar excess enthalpies for 1-butanol + heptane or + cyclohexane. Excess enthalpies of 1-butanethiol + alkane systems, which is contrary to the trend observed in 1-butanol + aromatic systems compared to 1-butanol + alkane systems. The excess enthalpy of 1-butanethiol + toluene is weakly exothermic.

  17. Endodontic treatments of mandibular first molar with middle mesial canal: two case reports.

    PubMed

    Lu, Qun; Wang, Ping; Yang, Bo; Liu, Xiao Jing; Wang, Shu Yong; Yu, Qing

    2013-01-01

    The mandibular first molars mostly have two mesial canals. In this report, two cases of mandibular first molars with three mesial canals are presented. The middle mesial canal was detected under endodontic microscope and further confirmed by cone-beam computed tomography and angled radiography, respectively. The purpose of this paper was to highlight the possibility of an aberrant root canal in a mandibular first molar and to help reduce the failure rates of the dental pulp treatment of the mandibular first molar. PMID:23878830

  18. Assessment of maxillary third molars with panoramic radiography and cone-beam computed tomography

    PubMed Central

    Jung, Yun-Hoa

    2015-01-01

    Purpose This study investigated maxillary third molars and their relation to the maxillary sinus using panoramic radiography and cone-beam computed tomography (CBCT). Materials and Methods A total of 395 maxillary third molars in 234 patients were examined using panoramic radiographs and CBCT images. We examined the eruption level of the maxillary third molars, the available retromolar space, the angulation, the relationship to the second molars, the number of roots, and the relationship between the roots and the sinus. Results Females had a higher frequency of maxillary third molars with occlusal planes apical to the cervical line of the second molar (Level C) than males. All third molars with insufficient retromolar space were Level C. The most common angulation was vertical, followed by buccoangular. Almost all of the Level C molars were in contact with the roots of the second molar. Erupted teeth most commonly had three roots, and completely impacted teeth most commonly had one root. The superimposition of one third of the root and the sinus floor was most commonly associated with the sinus floor being located on the buccal side of the root. Conclusion Eruption levels were differently distributed according to gender. A statistically significant association was found between the eruption level and the available retromolar space. When panoramic radiographs showed a superimposition of the roots and the sinus floor, expansion of the sinus to the buccal side of the root was generally observed in CBCT images. PMID:26730371

  19. Mandibular Third Molar Impaction: Review of Literature and a Proposal of a Classification

    PubMed Central

    Daugela, Povilas

    2013-01-01

    ABSTRACT Objectives The purpose of present article was to review impacted mandibular third molar aetiology, clinical anatomy, radiologic examination, surgical treatment and possible complications, as well as to create new mandibular third molar impaction and extraction difficulty degree classification based on anatomical and radiologic findings and literature review results. Material and Methods Literature was selected through a search of PubMed, Embase and Cochrane electronic databases. The keywords used for search were mandibular third molar, impacted mandibular third molar, inferior alveolar nerve injury third molar, lingual nerve injury third molar. The search was restricted to English language articles, published from 1976 to April 2013. Additionally, a manual search in the major anatomy and oral surgery journals and books was performed. The publications there selected by including clinical and human anatomy studies. Results In total 75 literature sources were obtained and reviewed. Impacted mandibular third molar aetiology, clinical anatomy, radiographic examination, surgical extraction of and possible complications, classifications and risk factors were discussed. New mandibular third molar impaction and extraction difficulty degree classification based on anatomical and radiologic findings and literature review results was proposed. Conclusions The classification proposed here based on anatomical and radiological impacted mandibular third molar features is promising to be a helpful tool for impacted tooth assessment as well as for planning for surgical operation. Further clinical studies should be conducted for new classification validation and reliability evaluation. PMID:24422029

  20. A histologic study of the width and nature of inter-radicular spaces in human adult pre-molars and molars.

    PubMed

    Heins, P J; Wieder, S M

    1986-06-01

    Serial sections of jaw segments from a human post mortem population of 29 individuals providing 116 posterior interproximal sites were examined at the light microscopic level. Minimum inter-root distances at the locale of closest proximity ranged from more than 4 mm to less than 0.1 mm. They were located in the coronal third of pre-molars and mandibular first and second molars and the middle third of maxillary first molars and second molar interproximal spaces. Cancellous bone flanked by lamina dura was found between 89.6% of the teeth examined and was observed where inter-root distances exceeded 0.5 mm. At sites of less than 0.5 mm, cancellous bone was not observed, and, instead, adjacent laminae durae appeared fused (7.7%). Bone was not observed between root surfaces which were less than 0.3 mm apart, but in these instances the roots were connected by a periodontal ligament. PMID:3458748

  1. Detection of Mesiobuccal Canal in Maxillary Molars and Distolingual Canal in Mandibular Molars by Dental CT: A Retrospective Study of 100 Cases

    PubMed Central

    Rathi, Sushma; Patil, Jayaprakash; Jaju, Prashant P.

    2010-01-01

    Objective. To detect presence of MB2 canal in maxillary molars and distolingual canal in mandibular molars by Dental CT. Material and Methods. A retrospective study of 100 Dental CTs was done. Axial and paraxial images obtained were used to assess the presence of MB2 canal in maxillary molars and distolingual canal in mandibular molars. Results. The youngest patient was of 11 years while the eldest patient was of 77 years. Males were 58 in number and females were 42 in number. MB2 canals were present in 57 patients and distolingual canal was present in 18 patients. Maximum MB2 canals were present in age group between 51 and 60 years, while distolingual canals were present in age group of 2130 years. Conclusion. Dental CT allows adequate visualization of variation in root canal morphology and can be important diagnostic tool for successful endodontic therapy. PMID:20613946

  2. Why arthroscopic partial meniscectomy?

    PubMed

    Lyu, Shaw-Ruey

    2015-09-01

    "Arthroscopic Partial Meniscectomy versus Sham Surgery for a Degenerative Meniscal Tear" published in the New England Journal of Medicine on December 26, 2013 draws the conclusion that arthroscopic partial medial meniscectomy provides no significant benefit over sham surgery in patients with a degenerative meniscal tear and no knee osteoarthritis. This result argues against the current practice of performing arthroscopic partial meniscectomy (APM) in patients with a degenerative meniscal tear. Since the number of APM performed has been increasing, the information provided by this study should lead to a change in clinical care of patients with a degenerative meniscus tear. PMID:26488013

  3. Why arthroscopic partial meniscectomy?

    PubMed Central

    2015-01-01

    Arthroscopic Partial Meniscectomy versus Sham Surgery for a Degenerative Meniscal Tear published in the New England Journal of Medicine on December 26, 2013 draws the conclusion that arthroscopic partial medial meniscectomy provides no significant benefit over sham surgery in patients with a degenerative meniscal tear and no knee osteoarthritis. This result argues against the current practice of performing arthroscopic partial meniscectomy (APM) in patients with a degenerative meniscal tear. Since the number of APM performed has been increasing, the information provided by this study should lead to a change in clinical care of patients with a degenerative meniscus tear. PMID:26488013

  4. [Gestational trophoblastic neoplasia after spontaneous normalization of human chorionic gonadotropin in patient with partial hydatidiform mole].

    PubMed

    Matos, Michelle; Ferraz, Leda; Lopes, Patrcia de Ftima; Lozoya, Consuelo; Amim Junior, Joffre; Rezende-Filho, Jorge; Braga, Antonio

    2015-07-01

    We report here a case of gestational trophoblastic neoplasia after spontaneous normalization of human chorionic gonadotropin in a patient with a partial hydatidiform mole. This is the second occurrence of this event to be reported and the first one with proven immunohistochemical evidence. Besides showing the treatment for this pregnancy complication, this case report discusses the possibility of reducing the duration of post-molar follow-up, as well as strategies for early recognition of gestational trophoblastic neoplasia after spontaneous remission of molar pregnancy. PMID:26247255

  5. The influence of impaction to the third molar mineralization in northwestern Chinese population.

    PubMed

    Guo, Yu-cheng; Yan, Chun-xia; Lin, Xing-wei; Zhang, Wen-tao; Zhou, Hong; Pan, Feng; Wei, Lai; Tang, Zheng; Liang, Feng; Chen, Teng

    2014-07-01

    Age estimation by third molar mineralization has been developed for a period of time. Recent studies showed that impaction status has an influence on the rate of the third molar mineralization in Europids and male Black African populations. In this regard, the present study was conducted to determine whether the impaction status could delay the chronological process of third molar mineralization in northwestern Chinese population too. A total of 3,512 digital orthopantomograms of 1,255 male and 2,257 female northwestern Chinese subjects aged from 11 to 26 years were assessed based on the formation stages described by Demirjian et al. with two modifications. Mineralization stage and impaction status were determined for all third molars. Statistical measures were calculated at stages C-H in the male and female gender for both impacted and non-impacted third molars. It was ascertained that the mean ages with impacted third molars at stages C-H were 0.02-1.42 years higher in males and 0.04-1.52 years higher in females than those with non-impacted third molars, but statistical differences were only found at stages C, D, and E in males and stages D and E in females. The probabilities of being under 14, 16, or 18 years of age with non-impacted third molars were all higher than those with impacted third molars. The results prove that impacted third molars show significant slower mineralization than non-impacted ones at stages D and E in both males and females of northwestern Chinese population. It is recommended to consider the influence of impaction on the rate of third molar mineralization for dental age estimation. PMID:24532176

  6. Prognosis of partial epilepsy.

    PubMed Central

    Porro, G; Matricardi, M; Guidetti, V; Benedetti, P

    1988-01-01

    The prognosis of partial epilepsy in childhood (excluding cases of benign partial epilepsy) was studied; the average follow up period was 7.4 years. Improvement rate of seizure status was 82.3%. We studied favourable prognostic factors and found that those most often associated with seizure improvement were familial convulsions and idiopathic forms, no generalised seizures before partial onset, low frequency of seizures after 12 months of treatment, short duration of epilepsy, and no background activity abnormalities on electroencephalography. We also observed such factors as mental retardation, neurological abnormalities, and behaviour and cognitive disorders. Factors that determined the prognosis for social adjustment were similar to those for seizure improvement. We discuss the favourable prognosis of partial seizures in childhood and the predictive factors. PMID:3143314

  7. Effect of Implant Diameter and Ridge Dimension on Stress Distribution in Mandibular First Molar Sites-A Photoelastic Study.

    PubMed

    Termeie, Deborah; Klokkevold, Perry R; Caputo, Angelo A

    2015-10-01

    The long-term clinical success of a dental implant is dependent upon maintaining sufficient osseointegration to resist forces of occlusion. The purpose of this study was to investigate the effect of implant diameter on stress distribution around screw-type dental implants in mandibular first molar sites using photoelastic models. The design included models with different buccal-lingual dimension. Twelve composite photoelastic models were assembled using 2 different resins to simulate trabecular and cortical bone. Half of the models were fabricated with average dimensions for ridge width and the other half with narrower buccal-lingual dimensions. One internal connection implant (13 mm length) with either a standard (4 mm), wide (5 mm), or narrow (3.3 mm) diameter was embedded in the first molar position of each photoelastic model. Half the implants were tapered and the other half were straight. Full gold crowns in the shape of a mandibular first molar were fabricated and attached to the implants. Vertical and angled loads of 15 and 30 pounds were applied to specific points on the crown. Wide-diameter implants produced the least stress in all ridges while narrow-diameter implants generated the highest stress, especially in narrow ridges. It may be that the volume and quality of bone surrounding implants influences stress distribution with a greater ratio of cortical to trabecular bone, thus providing better support. Models with wide-diameter implants loaded axially had a more symmetrical stress distribution compared to standard and narrow diameter implants. A more asymmetrical stress pattern developed along the entire implant length with angled loads. Implant diameter and ridge width had considerable influence on stress distribution. Narrow-diameter implants produced more stress than wide diameter implants in all conditions tested. PMID:25072829

  8. Partial gravity - Human impacts on facility design

    NASA Technical Reports Server (NTRS)

    Capps, Stephen; Moore, Nathan

    1990-01-01

    Partial gravity affects the body differently than earth gravity and microgravity environments. The main difference from earth gravity is human locomotion; while the main dfference from microgravity is the specific updown orientation and reach envelopes which increase volume requirements. Much data are available on earth gravity and microgravity design; however, very little information is available on human reactions to reduced gravity levels in IVA situations (without pressure suits). Therefore, if humans commit to permanent lunar habitation, much research should be conducted in the area of partial gravity effects on habitat design.

  9. Partially coherent lensfree tomographic microscopy?

    PubMed Central

    Isikman, Serhan O.; Bishara, Waheb; Ozcan, Aydogan

    2012-01-01

    Optical sectioning of biological specimens provides detailed volumetric information regarding their internal structure. To provide a complementary approach to existing three-dimensional (3D) microscopy modalities, we have recently demonstrated lensfree optical tomography that offers high-throughput imaging within a compact and simple platform. In this approach, in-line holograms of objects at different angles of partially coherent illumination are recorded using a digital sensor-array, which enables computing pixel super-resolved tomographic images of the specimen. This imaging modality, which forms the focus of this review, offers micrometer-scale 3D resolution over large imaging volumes of, for example, 1015 mm3, and can be assembled in light weight and compact architectures. Therefore, lensfree optical tomography might be particularly useful for lab-on-a-chip applications as well as for microscopy needs in resource-limited settings. PMID:22193016

  10. PARTIAL TORUS INSTABILITY

    SciTech Connect

    Olmedo, Oscar; Zhang Jie

    2010-07-20

    Flux ropes are now generally accepted to be the magnetic configuration of coronal mass ejections (CMEs), which may be formed prior to or during solar eruptions. In this study, we model the flux rope as a current-carrying partial torus loop with its two footpoints anchored in the photosphere, and investigate its stability in the context of the torus instability (TI). Previous studies on TI have focused on the configuration of a circular torus and revealed the existence of a critical decay index of the overlying constraining magnetic field. Our study reveals that the critical index is a function of the fractional number of the partial torus, defined by the ratio between the arc length of the partial torus above the photosphere and the circumference of a circular torus of equal radius. We refer to this finding as the partial torus instability (PTI). It is found that a partial torus with a smaller fractional number has a smaller critical index, thus requiring a more gradually decreasing magnetic field to stabilize the flux rope. On the other hand, a partial torus with a larger fractional number has a larger critical index. In the limit of a circular torus when the fractional number approaches 1, the critical index goes to a maximum value. We demonstrate that the PTI helps us to understand the confinement, growth, and eventual eruption of a flux-rope CME.

  11. Immediate function of partial fixed rehabilitation with axial and tilted implants having intrasinus insertion.

    PubMed

    Agliardi, Enrico Luigi; Tet, Stefano; Romeo, Davide; Malchiodi, Luciano; Gherlone, Enrico

    2014-05-01

    Implant-supported rehabilitation of the posterior maxilla could be challenging because hyperpneumatization of the maxillary sinus might reduce the bone height. In this study, the authors report preliminary results of a new treatment modality for the partial fixed rehabilitation of posterior maxilla with immediate function by using 1 anterior axial implant and 1 posterior tilted implant with intrasinus mesial insertion. From 2009 to 2011, 10 patients (6 women and 4 men) with missing upper premolars and molars were recruited and treated according to this protocol. Each patient received a partial fixed bridge supported by 1 axial anterior implant and 1 posterior implant placed with a 30-degree mesial inclination and intrasinus insertion. Autologous bone was positioned to fill the maxillary sinus cavity and to cover the exposed implant surface after elevation of the anterior sinus membrane. A prosthesis with immediate function was positioned within 3 hours, whereas a CAD/CAM final restoration was delivered 6 months later. Follow-ups at 6 and 12 months, and then annually, were scheduled. At each follow-up, plaque level and bleeding scores were assessed, and radiographic evaluation of marginal bone level change was performed at 1 year. The patients were followed up for a mean of 50 months (range, 42-57 mo). No implants were lost, and all prostheses were stable and functional, reporting 100% of implant and prosthetic success rates. After 1 year, bone loss had a mean (SD) of 1.0 (0.4) and 0.9 (0.5) mm for axial and tilted implants, respectively, with no statistically significant differences between them (P > 0.05). The preliminary results suggest that this approach could allow the rehabilitation of posterior maxilla with immediate function in case of reduced bone volume, representing an alternative technique to bone grafting, short implants, and zygomatic or pterygoid implants. PMID:24820712

  12. Removal of an Upper Third Molar from the Maxillary Sinus

    PubMed Central

    Amorim, Klinger de Souza; da Silva, Vanessa Tavares; da Cunha, Rafael Soares; Souto, Maria Luisa Silveira; So Mateus, Carla Rocha; Souza, Liane Maciel de Almeida

    2015-01-01

    The maxillary sinus or antrum is the largest of the paranasal sinuses. It is located in the maxillary bone and has a proximity to the apexes of upper molars and premolars, which allows it to form a direct link between the sinus and the oral cavity. Dislocation of a foreign body or tooth to the interior of a paranasal sinus is a situation that can occur as a result of car accidents, firearm attacks, or iatrogenic in surgical procedures. Therefore, it is necessary to know how to treat this kind of situation. This study's objective is to report the case of a 23-year-old female patient, leucoderma, who sought treatment from the Surgical Unit at the Dental Faculty of the Federal University of Sergipe. She had a history of pain and edema in the right side of the genian region and two failed attempts at removing dental unit (DU) 18. The extraoral clinical exam revealed intense edema of the left hemiface with signs of infection, excoriation of the labial commissure, hematoma, a body temperature of 39C, and a limited ability to open her mouth. The patient was medicated and treated surgically. The tooth was removed from the maxillary sinus with caution, as should have been done initially. PMID:25705524

  13. Variability of Australopithecus second maxillary molars from Sterkfontein Member 4.

    PubMed

    Fornai, Cinzia; Bookstein, Fred L; Weber, Gerhard W

    2015-08-01

    The question of how many Australopithecus species lived at Sterkfontein Member 4 and Makapansgat continues to be controversial inasmuch as the fossils are poorly preserved, the stratigraphy is difficult to interpret, and the cranial, dental, and postcranial remains are mostly not associated. To proceed we applied the most intensive modern methods of 3D geometric morphometrics to dental form, specifically the shapes of the upper second molars (M(2)s) in a sample combining 13 Australopithecus, 11 Paranthropus, and 23 Homo. We analyzed outer and inner crown surfaces, as well as crown and cervical outlines both separately and together, using a total of 16 landmarks, 51 curve semilandmarks, and 48 pseudolandmarks over the four structures. Outer and inner enamel surfaces are highly correlated in this dataset, while crown outline is the least informative of the four structures. Homo was easily distinguished from both Australopithecus and Paranthropus by these methods, likewise Homo sapiens from Homo neanderthalensis. There were, however, no stable classes within the Australopithecus sample or between Australopithecus and Paranthropus. Instead, there was a gradient along which Australopithecus prometheus and Australopithecus africanus lie toward the extremes, with Paranthropus overlapping both. If there are indeed different species at this site, then either their M(2) morphologies are uninformative or else the present sample is too small to make an accurate assessment. Our findings suggest that the variability of the Australopithecus specimens will be difficult to interpret authoritatively, independent of the method used. PMID:26163295

  14. MTA pulpotomy of human permanent molars with irreversible pulpitis.

    PubMed

    Eghbal, Mohammad Jafar; Asgary, Saeed; Baglue, Reza Ali; Parirokh, Masoud; Ghoddusi, Jamileh

    2009-04-01

    The histological success of mineral trioxide aggregate (MTA) pulpotomy for treatment of irreversible pulpitis in human teeth as an alternative treatment was investigated in this study. Fourteen molars which had to be extracted were selected from patients 16-28 years old. The selection criteria include carious pulp exposure with a history of lingering pain. After isolation, caries removal and pulp exposure, MTA was used in pulpotomy treatment. Patients were evaluated for pain after 24 h. Two patients were lost from this study. Twelve teeth were extracted after 2 months and were assessed histologically. Recall examinations confirmed that none of the patients experienced pain after pulpotomy. Histological observation revealed that all samples had dentin bridge formation completely and that the pulps were vital and free of inflammation. Although the results favour the use of MTA as a pulpotomy material, more studies with larger samples and a longer recall period are suggested to justify the use of MTA for treatment of irreversible pulpitis in human permanent teeth. PMID:19335509

  15. Molar crown inner structural organization in Javanese Homo erectus.

    PubMed

    Zanolli, Clément

    2015-01-01

    This contribution investigates the inner organizational pattern (tooth tissue proportions and enamel-dentine junction morphology) of seven Homo erectus permanent molar crowns from the late Lower-early Middle Pleistocene Kabuh Formation of the Sangiran Dome (Central Java, Indonesia). The previous study of their external characteristics confirmed the degree of time-related structural reduction occurred in Javanese H. erectus, and also revealed a combination of nonmetric features which are rare in the Lower and early Middle Pleistocene dental record, but more frequently found in recent humans. In accordance with their outer occlusal morphology, the specimens exhibit a set of derived internal features, such as thick to hyperthick enamel, an incomplete expression of the crest patterns at the enamel-dentine junction (EDJ) level, a sharp EDJ topography. As a whole, these features differ from those expressed in some penecontemporaneous specimens/samples representing African H. erectus/ergaster and H. heidelbergensis, as well as in Neanderthals, but occur in recent human populations. Further research in virtual dental paleoanthropology to be developed at macroregional scale would clarify the polarity and intensity of the intermittent exchanges between continental and insular Southeast Asia around the Lower to Middle Pleistocene boundary, as well as should shed light on the still poorly understood longitudinal evolutionary dynamics across continental Asia. PMID:25209431

  16. Management of middle mesial canal in mandibular second molar.

    PubMed

    Karunakaran, J V; Shobana, R; Kumar, Mohan; Kumar, Senthil; Mankar, Sunil

    2012-08-01

    The primary objective of endodontic therapy is to achieve a three-dimensional obturation of the root canal space after adequate preparation of the canal space to remove the tissue debris, microorganisms, and their byproducts. Anatomical variations have frequently been encountered in endodontic practice and have to be adequately managed by the clinician. Missed roots and canals are a major reason for failure of therapy. Technological advances have given the clinician ample opportunity to identify and treat these aberrations successfully. The present report describes a left mandibular second permanent molar requiring root canal treatment, found to have three separate canals in the mesial root. This case demonstrates a rare anatomical configuration and emphasizes the need for the clinician to be aware of and look out for such variations and use adequate diagnostic methodologies prior to and during therapy to detect such variations. The possibility of additional canals, whenever in doubt, should be explored with the assistance of technologies such as those of magnification and illumination and various diagnostic aids. Operator experience has also shown to be a key factor in negotiation and management of these aberrant canal configurations. PMID:23066241

  17. Concomitant Third Molar Removal During Sagittal Split Osteotomy of the Mandible.

    PubMed

    Sasaki, Ryo; Yao, Chuan-Fong; Chen, Ying-An; Lin, Cheng-Hui; Chen, Yu-Ray

    2016-01-01

    It is described in textbook about management of third molar in orthognathic surgery that "ideally, the third molars should be removed 9 to 12 months before sagittal split osteotomy (SSO)." At the Chang Gung Craniofacial Center, the authors always remove mandibular third molars during SSO, because: removal of third molars at the same time of SSO could reduce psychological stress on patients by saving 1 surgical procedure under local anesthesia, better exposure of impacted third molars could be facilitated by sagittal split of buccal cortical plate, rigid fixation could be performed without difficulty by our fixation method using plates and screws crossover anterior oblique line. Strong force during the elevation of third molars, however, may result in the fracture of distal segment of SSO, where the buccal cortical plate is relatively thin because of the presence of third molar. Therefore, more care needs to be taken in the surgical technique, which is different from ordinary tooth extraction. In this paper, the details of surgical procedure of third molar removal during SSO were reported. PMID:26745199

  18. Management of early loss of first permanent molar: a new technique.

    PubMed

    Rajashekhara, B S; Keyur, J M; Bhavna, D; Poonacha, K S

    2012-01-01

    The loss of a permanent first molar in adolescent patient creates a need for early space maintenance and restoration of function. To ascertain function and esthetics, immediate treatments include interim restorative approaches. This paper describes a conservative, functional and cost-effective bridge as an interim restoration after the loss of permanent first molar in an early adolescent dentition. PMID:23514691

  19. Modified Distal Shoe Appliance for Premature Loss of Multiple Deciduous Molars: A Case Report

    PubMed Central

    K., Navin H.; Idris, Mohammed; Christopher, Pradeep; Rai, Niharika

    2014-01-01

    Preservation of the primary dentition until the normal time of exfoliation is one of the most important factor involved in preventive and interceptive dentistry. The premature loss of second primary molar before the eruption of permanent first molar can create a significant arch space/tooth size discrepancy. Distal shoe space maintainer is a valuable part of the Paediatric Dentist’s armamentarium in those cases where the second primary molar is prematurely lost and it helps to guide the first permanent molar into place. Conventional design poses various limitations in cases of premature loss of multiple deciduous molars. Thus, it is required to modify the conventional designs according to the needs of the patient. This case report describes an innovative modification of distal shoe appliance in cases of premature loss of multiple deciduous molars. In the present case, modification of distal shoe space maintainer was advocated because of inadequate abutments caused due to multiple loss of deciduous molars. Bilateral design of distal shoe was planned for unilateral loss of deciduous molars. PMID:25302284

  20. Degradation of Ultra-High Molar Mass Polymers in Size-Exclusion Chromatography

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The degradation of high molar mass polymers during size-exclusion chromatography (SEC) analysis has been a topic of interest for several decades. Should a polymer degrade during analysis, the accuracy of the molar mass (M) and architectural information obtained will be compromised. To this effect,...

  1. Excess molar enthalpies of chloroalkanes or chloroalkene + 2-propyn-1-ol at 298.15 K

    SciTech Connect

    Kumar, R.V.; Rao, M.A.; Rao, M.V.; Prasad, D.H.L.

    1995-09-01

    Excess molar enthalpies for 2-propyn-1-ol + 1,2-dichloroethane, + 1,1,1,-trichloroethane, + 1,1,2,2-tetrachloroethane, and + trichloroethylene have been measured at 298.15 K with a Parr 1451 solution calorimeter. The excess molar enthalpies are positive over the entire range of composition.

  2. Endodontic treatment of a maxillary second molar with developmental anomaly: a case report.

    PubMed

    Asgary, Saeed

    2007-01-01

    Fusion is a rare occurrence in molar teeth. The purpose of this rare case presentation is to describe the nonsurgical endodontic treatment of maxillary molar. A 28-year-old patient was referred for endodontic treatment of her chronic apical abscess of right maxillary second molar. In the clinical examination, a sinus tract adjacent to involved tooth and a small crown of supernumerary tooth fused to the buccal surface of the molar at gingival margin was observed. Endodontic treatment was decided for the involved molar for functional reason. Recall examination, ayear after completion of endodontic and restorative treatments, showed the tooth was clinically asymptomatic and there was no radiographic lucency around the apical region. PMID:24327819

  3. A Noble, Easy and Conceptual Radiographic Analysis to Assess the Type of Tooth Movement (Molar Distalization)

    PubMed Central

    Prakash, Anaveri Thimmappa; Deepthi; Naik, Atri

    2015-01-01

    Context and Aim Bodily tooth movement is desirable in the field of Orthodontics and so is with molar distalization. Till date there is no such analysis available which could gauge and quantify the molar distalization and the type of tooth movement achieved, therefore one was required. Materials and Methods An OPG and Lateral cephalogram was used taking Inter orbitale plane and FH plane respectively as reference lines and the analysis was devised to measure the amount and type of tooth movement achieved in distalization of molar. Conclusion This analysis is a noble, easy and conceptual analysis to assess the type of tooth movement achieved during molar distalization and other molar movements using Lateral cephalogram and orthopantomogram. PMID:26436040

  4. Enamel thickness and the helicoidal wear plane in modern human mandibular molars.

    PubMed

    Schwartz, G T

    2000-05-01

    Helicoid occlusion has long been recognized as a feature characterizing the human dentition and has been viewed as an important morphological marker in the transition from Australopithecus to Homo. The hallmark of helicoidal wear is a buccal wear slope in anterior mandibular molars (and a corresponding lingual slope of wear in anterior maxillary molars) reversing to a flat or lingual-oriented one in posterior mandibular molars. If localized increases in enamel thickness are taken as evidence of an adaptation to increased wear resistance, then data on enamel thickness in unworn molars can be used to assess whether the region of greatest wear changes from anterior to posterior in such a way as to provide evidence for the helicoidal wear plane being a structural feature of the orofacial skeleton. Such a hypothesis was supported in a previous study on enamel thickness in modern human maxillary molars. As maxillary and mandibular precisely interdigitate, it is reasonable to expect that a similar pattern of enamel thickness distribution should be present in mandibular molars. To test this, data on the distribution of enamel thickness across functionally relevant regions of the crown were collected on a sample of twenty-nine completely unworn mandibular molars. Results suggest that enamel thickness increases slightly posteriorly but no evidence exists for morphological changes along the mandibular molar series of modern humans to follow a trend towards providing additional tooth material in areas under greater wear in accordance with a helicoidal wear model. This suggests that the patterning of enamel thickness must be viewed in conjunction with other features, such as the biomechanical behaviour of molars during occlusion and axial molar angulation, to ascertain the precise anatomical determinants of this unique feature of the human dentition. PMID:10739861

  5. Comparison of Primary Molar Crown Dimensions with Stainless Steel Crowns in a Sample of Iranian Children.

    PubMed

    Afshar, Hossein; Kamali Sabeti, Arghavan; Shahrabi, Mahdi

    2015-01-01

    Background and aims. Due to anatomic variation in tooth anatomy between populations, this study compared the buccolingual (BL) and mesiodistal (MD) dimensions of primary molars with those of stainless steel crowns (SSCs) in anIranian population. Materials and methods. Impressions were taken from both dental arches of children, and casts were poured. Teeth with caries, restoration, hypoplasia or other dental anomalies were excluded. 216 primary molars were selected and divided into 4 groups of 54 each (maxillary and mandibular first and second primary molars). MD/BL dimensions were measured using a digital caliper with 0.01 mm precision on casts and SCCs (3M brand). Data were assessed using paired t-test, post hoc test and ANOVA. P < 0.05 was considered statistically significant. Results. The MD dimension of the lower first molar SSC and the BL dimension of the lower second molar SSC had the least difference with the corresponding values of the respective teeth. The MD dimension of the upper second molar SSC and the BL dimension of the upper first molar SSC had the greatest difference with the corresponding values in the respective teeth. Comparison of the two different brands of SSCs for the upper first molar revealed that both types had significant differences with the teeth in terms of both MD (P = 0.0) and BL (P = 0.0) dimensions. Conclusion. In the studied population, best adaptation was seen in second lower molars and the least adaptationswere seen in first and second upper molars. PMID:26236433

  6. Comparison of Primary Molar Crown Dimensions with Stainless Steel Crowns in a Sample of Iranian Children

    PubMed Central

    Afshar, Hossein; Kamali Sabeti, Arghavan; Shahrabi, Mahdi

    2015-01-01

    Background and aims. Due to anatomic variation in tooth anatomy between populations, this study compared the buccolingual (BL) and mesiodistal (MD) dimensions of primary molars with those of stainless steel crowns (SSCs) in anIranian population. Materials and methods. Impressions were taken from both dental arches of children, and casts were poured. Teeth with caries, restoration, hypoplasia or other dental anomalies were excluded. 216 primary molars were selected and divided into 4 groups of 54 each (maxillary and mandibular first and second primary molars). MD/BL dimensions were measured using a digital caliper with 0.01 mm precision on casts and SCCs (3M brand). Data were assessed using paired t-test, post hoc test and ANOVA. P < 0.05 was considered statistically significant. Results. The MD dimension of the lower first molar SSC and the BL dimension of the lower second molar SSC had the least difference with the corresponding values of the respective teeth. The MD dimension of the upper second molar SSC and the BL dimension of the upper first molar SSC had the greatest difference with the corresponding values in the respective teeth. Comparison of the two different brands of SSCs for the upper first molar revealed that both types had significant differences with the teeth in terms of both MD (P = 0.0) and BL (P = 0.0) dimensions. Conclusion. In the studied population, best adaptation was seen in second lower molars and the least adaptationswere seen in first and second upper molars. PMID:26236433

  7. Dietary Inference from Upper and Lower Molar Morphology in Platyrrhine Primates

    PubMed Central

    Allen, Kari L.; Cooke, Siobhn B.; Gonzales, Lauren A.; Kay, Richard F.

    2015-01-01

    The correlation between diet and dental topography is of importance to paleontologists seeking to diagnose ecological adaptations in extinct taxa. Although the subject is well represented in the literature, few studies directly compare methods or evaluate dietary signals conveyed by both upper and lower molars. Here, we address this gap in our knowledge by comparing the efficacy of three measures of functional morphology for classifying an ecologically diverse sample of thirteen medium- to large-bodied platyrrhines by diet category (e.g., folivore, frugivore, hard object feeder). We used Shearing Quotient (SQ), an index derived from linear measurements of molar cutting edges and two indices of crown surface topography, Occlusal Relief (OR) and Relief Index (RFI). Using SQ, OR, and RFI, individuals were then classified by dietary category using Discriminate Function Analysis. Both upper and lower molar variables produce high classification rates in assigning individuals to diet categories, but lower molars are consistently more successful. SQs yield the highest classification rates. RFI and OR generally perform above chance. Upper molar RFI has a success rate below the level of chance. Adding molar length enhances the discriminatory power for all variables. We conclude that upper molar SQs are useful for dietary reconstruction, especially when combined with body size information. Additionally, we find that among our sample of platyrrhines, SQ remains the strongest predictor of diet, while RFI is less useful at signaling dietary differences in absence of body size information. The study demonstrates new ways for inferring the diets of extinct platyrrhine primates when both upper and lower molars are available, or, for taxa known only from upper molars. The techniques are useful in reconstructing diet in stem representatives of anthropoid clade, who share key aspects of molar morphology with extant platyrrhines. PMID:25738266

  8. The pH-responsive behaviour of poly(acrylic acid) in aqueous solution is dependent on molar mass.

    PubMed

    Swift, Thomas; Swanson, Linda; Geoghegan, Mark; Rimmer, Stephen

    2016-02-23

    Fluorescence spectroscopy on a series of aqueous solutions of poly(acrylic acid) containing a luminescent label showed that polymers with molar mass, Mn < 16.5 kDa did not exhibit a pH responsive conformational change, which is typical of higher molar mass poly(acrylic acid). Below this molar mass, polymers remained in an extended conformation, regardless of pH. Above this molar mass, a pH-dependent conformational change was observed. Diffusion-ordered nuclear magnetic resonance spectroscopy confirmed that low molar mass polymers did not undergo a conformational transition, although large molar mass polymers did exhibit pH-dependent diffusion. PMID:26822456

  9. Oxygen partial pressure sensor

    DOEpatents

    Dees, Dennis W. (Downers Grove, IL)

    1994-01-01

    A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured.

  10. Methanol partial oxidation reformer

    DOEpatents

    Ahmed, Shabbir (Bolingbrook, IL); Kumar, Romesh (Naperville, IL); Krumpelt, Michael (Naperville, IL)

    1999-01-01

    A partial oxidation reformer comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell.

  11. Methanol partial oxidation reformer

    DOEpatents

    Ahmed, Shabbir (Bolingbrook, IL); Kumar, Romesh (Naperville, IL); Krumpelt, Michael (Naperville, IL)

    2001-01-01

    A partial oxidation reformer comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell.

  12. Methanol partial oxidation reformer

    DOEpatents

    Ahmed, S.; Kumar, R.; Krumpelt, M.

    1999-08-24

    A partial oxidation reformer is described comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell. 7 figs.

  13. Methanol partial oxidation reformer

    DOEpatents

    Ahmed, S.; Kumar, R.; Krumpelt, M.

    1999-08-17

    A partial oxidation reformer is described comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell. 7 figs.

  14. Oxygen partial pressure sensor

    DOEpatents

    Dees, D.W.

    1994-09-06

    A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured. 1 fig.

  15. Complex cellular responses to tooth wear in rodent molar.

    PubMed

    Mahdee, A; Alhelal, A; Eastham, J; Whitworth, J; Gillespie, J I

    2016-01-01

    The arrangement and roles of the odontoblast and its process in sensing and responding to injuries such as tooth wear are incompletely understood. Evidence is presented that dentine exposure by tooth wear triggers structural and functional changes that aim to maintain tooth integrity. Mandibular first molars from freshly culled 8 week Wistar rats were prepared for light microscopy ground-sections (n=6), or fixed in 4% paraformaldehyde, decalcified in 17% EDTA, sectioned and stained with antibodies to cyto-skeletal proteins (vimentin (vim), ?-tubulin (tub) and ?-actin), cellular homeostatic elements (sodium potassium ATPase (NaK-ATPase) and sodium hydrogen exchanger (NHE-1)), and sensory nerve fibres (CGRP) (n=10) for fluorescence microscopy of worn and unworn regions of the mesial cusp. Immunoreactivity (IR) to vim, actin, NaK-ATPase and CGRP was confined to the pulpal third of odontoblast processes (OPs). IR to tub and nhe-1 was expressed by OPs in full dentine thickness. In areas associated with dentine exposure, the tubules contained no OPs. In regions with intact dentine, odontoblasts were arranged in a single cell layer and easily distinguished from the sub-odontoblast cells. In regions with open tubules, the odontoblasts were in stratified or pseudo-stratified in arrangement. Differences in structural antibody expression suggest a previously unreported heterogeneity of the odontoblast population and variations in different regions of the OP. This combined with differences in OPs extension and pulp cellular arrangement in worn and unworn regions suggests active and dynamic cellular responses to the opening of dentinal tubules by tooth wear. PMID:26547699

  16. Partially strong WW scattering

    SciTech Connect

    Cheung Kingman; Chiang Chengwei; Yuan Tzuchiang

    2008-09-01

    What if only a light Higgs boson is discovered at the CERN LHC? Conventional wisdom tells us that the scattering of longitudinal weak gauge bosons would not grow strong at high energies. However, this is generally not true. In some composite models or general two-Higgs-doublet models, the presence of a light Higgs boson does not guarantee complete unitarization of the WW scattering. After partial unitarization by the light Higgs boson, the WW scattering becomes strongly interacting until it hits one or more heavier Higgs bosons or other strong dynamics. We analyze how LHC experiments can reveal this interesting possibility of partially strong WW scattering.

  17. National clinical guidelines for the extraction of first permanent molars in children.

    PubMed

    Cobourne, M T; Williams, A; Harrison, M

    2014-12-01

    This article summarises recently updated guidelines produced by the Clinical Governance Directorate of the British Orthodontic Society through the Clinical Standards Committee of the Faculty of Dental Surgery, Royal College of Surgeons of England (FDSRCS) on the extraction of first permanent molars in children. The first permanent molar is susceptible to chronological enamel defects, molar-incisor hypomineralisation and caries, which may necessitate enforced extraction in the developing dentition. In the right circumstances, the extraction of these teeth can be followed by successful eruption of the second permanent molar and ultimately, third molar eruption to complete the molar dentition. For this reason, elective extraction of first permanent molars with a questionable long-term prognosis should be considered when planning enforced extractions. However, a number of factors can influence the decision-making process, including the necessity for a general anaesthetic to allow extraction, potential cooperation with restorative or orthodontic treatment and likely future preventative practice within the family. Moreover, the presence of any underlying malocclusion also needs to be evaluated within the context of extraction planning. The current available evidence has been evaluated and awarded a grade based upon those recommended by the Scottish Intercollegiate Guidelines Network. PMID:25476643

  18. Use of cone beam imaging to assess inter-root distance in molar furcations.

    PubMed

    Dutra, Danilo Antonio Milbradt; da Silva, Felipe Borges; Moreira, Carlos Heitor Cunha; Kantorski, Karla Zanini

    2014-01-01

    This study used cone beam computed tomography (CBCT) to evaluate distances among root surfaces in molar furcations and assess the congruence between inter-root distances in molar furcations and curette blade widths. Distances among root surfaces at 1 and 3 mm from the fornix of molar furcations (points A and B, respectively) were measured with standardized CBCT images and analyzed using computer software. Periodontal curette widths were evaluated by digital caliper and stereomicroscope (magnification 10x). Forty CBCT images (containing a total of 141 molar teeth and 354 furcations) were evaluated; 19 furcations (5.4%) with fused molars were excluded. Mesial furcations of the first molars had the highest average inter-root distances (point A: 3.81 0.87 mm; point B: 5.30 0.92 mm), while buccal furcations of the maxillary second molars had the smallest average distances (point A: 1.49 0.37 mm; point B: 1.90 0.65 mm). Analysis of 107 curettes revealed statistically significant differences among curette types and manufacturers. Pearson's coefficient revealed a strong and significant correlation for curette measurement using digital caliper and stereomicroscope (r = 0.86, P < 0.01). In most cases, the curettes tested allowed access for scaling and root planing of teeth with furcation involvement. PMID:24598502

  19. Intrusion of overerupted upper first molar using two orthodontic miniscrews. A case report.

    PubMed

    Kravitz, Neal D; Kusnoto, Budi; Tsay, Peter T; Hohlt, William F

    2007-09-01

    Loss of the mandibular first molar often leads to the overeruption of the opposing maxillary first molar, resulting in occlusal interference, loss of periodontal bony support, and inadequate room to restore the mandibular edentulous space. Without orthodontic molar intrusion or segmental surgical impaction, restoring the posterior occlusion often entails the need for significant reduction of maxillary molar crown height, with the potential need for costly iatrogenic root canal therapy and restoration. The literature has cited successful maxillary molar intrusion with minor prosthodontic reduction using palatal orthodontic miniscrews and buccal zygomatic miniplates. In this report, the authors present successful maxillary molar intrusion with two orthodontic miniscrews in a patient with extreme dental anxiety and significant dental erosion due to gastric reflux. Using two orthodontic miniscrews for skeletal anchorage to intrude the maxillary molar simplified the orthodontic treatment by eliminating the need for extensive surgery, headgear, and intraoral multiunit anchorage and preserved indispensable tooth enamel. The clinical results showed significant intrusion through the maxillary sinus cortical floor while maintaining periodontal health, tooth vitality, and root length. PMID:17902236

  20. Prevalence of taurodontism in primary mandibular first molars of ethnic Indian children.

    PubMed

    Nagaveni, N B; Radhika, N B

    2012-01-01

    The objective of this study was to determine the prevalence of taurodontism in primary mandibular first molars in ethnic Indian children using periapical radiographs. Periapical radiographs of 274 children obtained from December 2008 to August 2010 were retrospectively screened and examined. Radiographs of 196 patients (99 boys and 97 girls; ages 2.5-10.5) with bilateral primary mandibular first molars were randomly selected and evaluated. The gender, symmetry, and frequencies of occurrence of taurodont primary mandibular first molars were compared and the obtained data were statistically analyzed using the x2 test. Eight (4.08%) taurodont primary mandibular first molars were found with a bilateral incidence of a symmetrical distribution of 38% (3/8). The prevalence of taurodontism in primary mandibular first molars did not differ significantly between right and left sides or with gender (P ? 0.05). The results of the present study indicate that approximately 4% of Indian children had taurodontism in primary mandibular first molars. Clinicians should be aware of the prevalence of this anatomic variant in primary mandibular first molars among the Indian population for early identification of taurodonts and for rendering the best care during dental treatment. PMID:23032243

  1. Prevalence and features of distolingual roots in mandibular molars analyzed by cone-beam computed tomography

    PubMed Central

    Choi, Mi-Ree; Moon, Young-Mi

    2015-01-01

    Purpose This study evaluated the prevalence of distolingual roots in mandibular molars among Koreans, the root canal system associated with distolingual roots, and the concurrent appearance of a distolingual root in the mandibular first molar and a C-shaped canal in the mandibular second molar. Materials and Methods Cone-beam computed tomographic images of 264 patients were screened and examined. Axial sections of 1056 mandibular molars were evaluated to determine the number of roots. The interorifice distances from the distolingual canal to the distobuccal canal were also estimated. Using an image analysis program, the root canal curvature was calculated. Pearson's chi-square test, the paired t-test, one-way analysis of variance, and post-hoc analysis were performed. Results Distolingual roots were observed in 26.1% of the subjects. In cases where a distolingual root was observed in the mandibular molar, a significant difference was observed in the root canal curvature between the buccolingual and mesiodistal orientations. The maximum root canal curvature was most commonly observed in the mesiodistal orientation in the coronal portion, but in the apical portion, maximum root canal curvature was most often observed in the buccolingual orientation. Conclusion The canal curvature of distolingual roots was found to be very complex, with a different direction in each portion. No correlation was found between the presence of a distolingual root in the mandibular first molar and the presence of a C-shaped canal in the mandibular second molar. PMID:26730369

  2. Morphology of the Physiological Apical Foramen in Maxillary and Mandibular First Molars

    PubMed Central

    Abarca, J.; Zaror, C.; Monardes, H.; Hermosilla, V.; Muñoz, C.; Cantin, M.

    2015-01-01

    SUMMARY Information regarding the anatomy of the physiological apical foramen is limited. Knowing its diameter and shapes contributes to clinical work, specifically to the cleaning and shaping of the apical third. The aim of this ex vivo study was to determine the minimum and maximum diameters and shape of the physiological apical foramen in the roots of maxillary and mandibular first molars. A descriptive study was conducted on 89 recently extracted first molars. Roots 3–5 mm from the apex were sectioned and prepared for analysis at 40× magnification. The minimum and maximum diameters of each physiological foramen were measured using the program Motic Images plus 2.0 ML. The shape of the foramina, classified as round, oval or irregular, was determined by the difference between the maximum and minimum diameters. A total of 174 physiological foramina were analyzed. The average of the minimum and maximum diameters was between 0.24–0.33 mm in maxillary first molars and between 0.25–0.33 mm in mandibular first molars. In maxillary molars, the most common shape of the foramen was oval (50%), then irregular (32%), then round (18%). In mandibular molars, the oval shape was also the most frequent (59%), followed by irregular (23%) and round (18%). The findings of this study regarding the morphology of physiological apical foramina in first molars make it easier for the operator to choose the appropriately-sized instruments to perform endodontic therapy successfully. PMID:25937698

  3. Arthroscopic partial wrist fusion.

    PubMed

    Ho, Pak-Cheong

    2008-12-01

    The wide intraarticular exposure of the wrist joint under arthroscopic view provides an excellent ground for various forms of partial wrist fusion. Combining with percutaneous fixation technique, arthroscopic partial wrist fusion can potentially generate the best possible functional outcome by preserving the maximal motion pertained with each type of partial wrist fusion because the effect of extraarticular adhesion associated with open surgery can be minimized. From November 1997 to May 2008, the author had performed 12 cases of arthroscopic partial wrist fusion, including scaphotrapeziotrapezoid fusion in 3, scaphoidectomy and 4-corner fusion in 4, radioscapholunate fusion in 3, radiolunate fusion in 1, and lunotriquetral fusion in 1 case. Through the radiocarpal or midcarpal joint, the corresponding articular surfaces were denuded of cartilage using arthroscopic burr and curette. Carpal bones involved in the fusion process were then transfixed with K wires percutaneously after alignment corrected and confirmed under fluoroscopic control. Autogenous cancellous bone graft or bone substitute were inserted and impacted to the fusion site through cannula under direct arthroscopic view. Final fixation could be by multiple K wires or cannulated screw system. Early mobilization was encouraged. Surgical complications were minor, including pin tract infection, skin burn, and delay union in 1 case. Uneventful radiologic union was obtained in 9 cases, stable fibrous union in 2, and nonunion in 1. The average follow-up period was 70 months. Symptom was resolved or improved, and functional motion was gained in all cases. All surgical scars were almost invisible, and aesthetic outcome was excellent. PMID:19060685

  4. Partial hue-matching.

    PubMed

    Logvinenko, Alexander D; Beattie, Lesley L

    2011-01-01

    It is widely believed that color can be decomposed into a small number of component colors. Particularly, each hue can be described as a combination of a restricted set of component hues. Methods, such as color naming and hue scaling, aim at describing color in terms of the relative amount of the component hues. However, there is no consensus on the nomenclature of component hues. Moreover, the very notion of hue (not to mention component hue) is usually defined verbally rather than perceptually. In this paper, we make an attempt to operationalize such a fundamental attribute of color as hue without the use of verbal terms. Specifically, we put forth a new method--partial hue-matching--that is based on judgments of whether two colors have some hue in common. It allows a set of component hues to be established objectively, without resorting to verbal definitions. Specifically, the largest sets of color stimuli, all of which partially match each other (referred to as chromaticity classes), can be derived from the observer's partial hue-matches. A chromaticity class proves to consist of all color stimuli that contain a particular component hue. Thus, the chromaticity classes fully define the set of component hues. Using samples of Munsell papers, a few experiments on partial hue-matching were carried out with twelve inexperienced normal trichromatic observers. The results reinforce the classical notion of four component hues (yellow, blue, red, and green). Black and white (but not gray) were also found to be component colors. PMID:21742961

  5. Partial polarizer filter

    NASA Technical Reports Server (NTRS)

    Title, A. M. (inventor)

    1978-01-01

    A birefringent filter module comprises, in seriatum. (1) an entrance polarizer, (2) a first birefringent crystal responsive to optical energy exiting the entrance polarizer, (3) a partial polarizer responsive to optical energy exiting the first polarizer, (4) a second birefringent crystal responsive to optical energy exiting the partial polarizer, and (5) an exit polarizer. The first and second birefringent crystals have fast axes disposed + or -45 deg from the high transmitivity direction of the partial polarizer. Preferably, the second crystal has a length 1/2 that of the first crystal and the high transmitivity direction of the partial polarizer is nine times as great as the low transmitivity direction. To provide tuning, the polarizations of the energy entering the first crystal and leaving the second crystal are varied by either rotating the entrance and exit polarizers, or by sandwiching the entrance and exit polarizers between pairs of half wave plates that are rotated relative to the polarizers. A plurality of the filter modules may be cascaded.

  6. Extraoral vs intraoral appliance for distal movement of maxillary first molars: a randomized controlled trial.

    PubMed

    Bondemark, Lars; Karlsson, Ingela

    2005-09-01

    Using randomized controlled trial methodology, the aim of this study was to evaluate and compare the treatment effects of an extraoral appliance (EOA) and an intraoral appliance (IOA) for distal movement of maxillary first molars. A total of 40 patients (mean 11.5 years, SD 1.29) at the Orthodontic Clinic, National Health Service, Skane County Council, Malm, Sweden, were randomized to receive treatment with either extraoral traction (cervical headgear) or an IOA using superelastic coils for distal movement of maxillary first molars. The inclusion criteria were a nonextraction treatment plan, a Class II molar relationship and maxillary first molars in occlusion with no erupted maxillary second molars. The outcome measures to be assessed in the trial were treatment time, cephalometric analysis of distal molar movement, anterior movement of maxillary central incisors, ie, anchorage loss and sagittal and vertical skeletal positional changes of the maxilla and mandible. In the IOA group, the molars were distalized during an average time of 5.2 months, whereas in the EOA group the corresponding time was 6.4 months (P < .01). The mean amount of distal molar movement was significantly higher in the IOA than in the EOA group, three mm vs 1.7 mm (P < .001). Moderate anchorage loss was produced with the IOA implying increased overjet (0.9 mm) whereas the EOA created decreased overjet (0.9 mm). It can be concluded that the IOA was more effective than the EOA to create distal movement of the maxillary first molars. PMID:16279817

  7. Developmental constraints revealed by co-variation within and among molar rows in two murine rodents.

    PubMed

    Renaud, Sabrina; Pantalacci, Sophie; Quéré, Jean-Pierre; Laudet, Vincent; Auffray, Jean-Christophe

    2009-01-01

    Morphological integration corresponds to interdependency between characters that can arise from several causes. Proximal causes of integration include that different phenotypic features may share common genetic sets and/or interact during their development. Ultimate causes may be the prolonged effect of selection favoring integration of functionally interacting characters, achieved by the molding of these proximal causes. Strong and direct interactions among successive teeth of a molar row are predicted by genetic and developmental evidences. Functional constraints related to occlusion, however, should have selected more strongly for a morphological integration of occluding teeth and a corresponding evolution of the underlying developmental and genetic pathways. To investigate how these predictions match the patterns of phenotypic integration, we studied the co-variation among the six molars of the murine molar row, focusing on two populations of house mice (Mus musculus domesticus) and wood mice (Apodemus sylvaticus). The size and shape of the three upper and lower molars were quantified and compared. Our results evidenced similar patterns in both species, size being more integrated than shape among all the teeth, and both size and shape co-varying strongly between adjacent teeth, but also between occluding teeth. Strong co-variation within each molar row is in agreement with developmental models showing a cascade influence of the first molar on the subsequent molars. In contrast, the strong co-variation between molars of the occluding tooth rows confirms that functional constraints molded patterns of integration and probably the underlying developmental pathways despite the low level of direct developmental interactions occurring among molar rows. These patterns of co-variation are furthermore conserved between the house mouse and the wood mouse that diverged >10 Ma, suggesting that they may constitute long-running constraints to the diversification of the murine rodent dentition. PMID:19754715

  8. Influence on the pressure on the properties of chromatographic columns III. Retention volume of thiourea, hold-up volume, and compressibility of the C18-bonded layer

    SciTech Connect

    Gritti, Fabrice; Guiochon, Georges A

    2005-05-01

    The influence of the average column pressure (ACP) on the elution volume of thiourea was measured on two RPLC columns, packed with Resolve-C{sub 18} (surface coverage 2.45 {micro} mol/m{sup 2}) and Symmetry-C{sub 18} (surface coverage 3.18 {micro} mol/m{sup 2}), and it was compared to that measured under the same conditions on an underivatized silica (Resolve). Five different methanol-water mixtures (20, 40, 60, 80 and 100% methanol, v/v) were used. Once corrected for the compressibility of the mobile phase, the data show that the elution volume of thiourea increases between 3 and 7% on the C{sub 18}-bonded columns when the ACP increases from 50 to 350 bar, depending on the methanol content of the eluent. No such increase is observed on the underivatized Resolve silica column. This increase is too large to be ascribed to the compressibility of the stationary phase (silica + C{sub 18} bonded chains) which accounts for less than 5% of the variation of the retention factor. It is shown that the reason for this effect is of thermodynamic origin, the difference between the partial molar volume of the solute in the stationary and the mobile phase, {Delta}V, controlling the retention volume of thiourea. While {Delta}V is nearly constant for all mobile phase compositions on Resolve silica (with {Delta}V {approx_equal} -4 mL/mol), on RPLC phases, it significantly increases with increasing methanol content, particularly above 60% methanol. It varies between - 5 mL/mol and - 17 mL/mol on Resolve-C{sub 18} and between - 9 mL/mol and - 25 mL/mol on Symmetry-C{sub 18}. The difference in surface coverage between these two RP-HPLC stationary phases increases the values of {Delta}V by about 5 mL/mol.

  9. Influence of the pressure on the properties of chromatographic columns III. Retention volume of thiourea, hold-up volume, and compressibility of the C18-bonded layer

    SciTech Connect

    Gritti, Fabrice; Guiochon, Georges A

    2005-04-01

    The influence of the average column pressure (ACP) on the elution volume of thiourea was measured on two RPLC columns, packed with Resolve-C{sub 18} (surface coverage 2.45 {micro} mol/m{sup 2}) and Symmetry-C{sub 18} (surface coverage 3.18 {micro} mol/m{sup 2}), and it was compared to that measured under the same conditions on an underivatized silica (Resolve). Five different methanol-water mixtures (20, 40, 60, 80 and 100% methanol, v/v) were used. Once corrected for the compressibility of the mobile phase, the data show that the elution volume of thiourea increases between 3 and 7% on the C{sub 18}-bonded columns when the ACP increases from 50 to 350 bar, depending on the methanol content of the eluent. No such increase is observed on the underivatized Resolve silica column. This increase is too large to be ascribed to the compressibility of the stationary phase (silica + C{sub 18} bonded chains) which accounts for less than 5% of the variation of the retention factor. It is shown that the reason for this effect is of thermodynamic origin, the difference between the partial molar volume of the solute in the stationary and the mobile phase, {Delta}V, controlling the retention volume of thiourea. While {Delta}V is nearly constant for all mobile phase compositions on Resolve silica (with {approx_equal} -4 mL/mol), on RPLC phases, it significantly increases with increasing methanol content, particularly above 60% methanol. It varies between -5 mL/mol and -17 mL/mol on Resolve-C{sub 18} and between -9 mL/mol and -25 mL/mol on Symmetry-C{sub 18}. The difference in surface coverage between these two RP-HPLC stationary phases increases the values of {Delta}V by about 5 mL/mol.

  10. Non Syndromic Bilateral Microdontia of Maxillary Second Molars: A Very Rare Finding

    PubMed Central

    Chander, Subhash; Ahluwalia, Amrit Singh; Chinna, Harleen

    2015-01-01

    Dental anomalies are the formative defects caused by genetic disturbances or environmental factors during tooth morphogenesis. The term microdontia is defined as the condition of having abnormally small teeth. Clinically, microdontia in the permanent dentition, excluding the third molars, is found in 0.8-8.4% of the population. One of the commonest forms of localized microdontia is that which affects the maxillary lateral incisor, a condition called Peg laterals. The next tooth which can be affected is the third molars. Few cases of microdontia in canines have been reported. Localised microdontia of maxillary second molar has never been reported in literature before. PMID:26023663

  11. Paediatric dentistry in the new millennium: 4. Cost-effective restorative techniques for primary molars.

    PubMed

    Duggal, M S; Gautam, S K; Nichol, R; Robertson, A J

    2003-10-01

    In the fourth article in this series the techniques for carrying out pulp therapy and stainless steel restoration in primary molars are discussed. Early pulp involvement in primary molars means that pulp therapy and the use of appropriate coronal restoration, such as stainless steel crowns, are indispensable if repetitive restoration of primary molars is to be avoided. These techniques themselves are not difficult to carry out once the child's co-operation is established and should be well within the capability of any dentist with an interest in the dental care of children. PMID:14619729

  12. Anatomical aberrations in root canals of maxillary first and second molar teeth: an endodontic challenge

    PubMed Central

    Shah, Manish; Patel, Pathik; Desai, Parth; Patel, Jayanti R

    2014-01-01

    Root canal anatomy variations present a constant challenge in successful diagnosis and endodontic treatment, especially the multirooted teeth. Maxillary first molar is the most commonly treated tooth yet with frequent failures because of undetected canals, especially the mesiobuccal second canal (MB2) with more frequency and distobuccal second canal (DB2) with quite a less frequency. Also, there are limited chances to find MB2 in maxillary second molars. We present two such cases, each of maxillary first and second molar with extra distobuccal and mesiobuccal canals, respectively. PMID:24445844

  13. Endodontic Management of Maxillary First Molar with Type I Canal Configuration A Rare Case Report

    PubMed Central

    Desai, Niranjan; Raghavendra, Srinidhi Surya; Mittal, Priya; Patil, Gururaj

    2015-01-01

    Thorough knowledge about the root canal variations is essential for the predictable endodontic treatment outcome. The root and root canal anatomy of maxillary first molar varies greatly. A Pub-med literature search about single rooted single canalled maxillary first molar was done to know its details such as incidence, diagnostic method used, age, sex and ethnic background of patient. This article presented report of a single rooted single canalled maxillary first molar in a 27-year-old healthy Asian female. PMID:26023655

  14. [The appearance test of a molar tooth with phase shift shadow moir].

    PubMed

    Mi, Honglin

    2013-08-01

    Modern photo-mechanics testing techniques are widely used in industrial circles and academic circles. In order to solve the problem of biomedical engineering, shadow moir method is used in oral and dental area in our study. A molar tooth was tested by phase shift shadow moir method. Through testing molar tooth, the results show that shadow moir method could be used for measuring the appearance of the oral area and concave and convex parts of molar tooth could also be distinguished and shown by interference patterns. The characteristics of shadow moirh are that it does't need exerting load on the specimen and could realize non-contact measurement. PMID:24059045

  15. The CPA Equation of State and an Activity Coefficient Model for Accurate Molar Enthalpy Calculations of Mixtures with Carbon Dioxide and Water/Brine

    SciTech Connect

    Myint, P. C.; Hao, Y.; Firoozabadi, A.

    2015-03-27

    Thermodynamic property calculations of mixtures containing carbon dioxide (CO2) and water, including brines, are essential in theoretical models of many natural and industrial processes. The properties of greatest practical interest are density, solubility, and enthalpy. Many models for density and solubility calculations have been presented in the literature, but there exists only one study, by Spycher and Pruess, that has compared theoretical molar enthalpy predictions with experimental data [1]. In this report, we recommend two different models for enthalpy calculations: the CPA equation of state by Li and Firoozabadi [2], and the CO2 activity coefficient model by Duan and Sun [3]. We show that the CPA equation of state, which has been demonstrated to provide good agreement with density and solubility data, also accurately calculates molar enthalpies of pure CO2, pure water, and both CO2-rich and aqueous (H2O-rich) mixtures of the two species. It is applicable to a wider range of conditions than the Spycher and Pruess model. In aqueous sodium chloride (NaCl) mixtures, we show that Duan and Sun’s model yields accurate results for the partial molar enthalpy of CO2. It can be combined with another model for the brine enthalpy to calculate the molar enthalpy of H2O-CO2-NaCl mixtures. We conclude by explaining how the CPA equation of state may be modified to further improve agreement with experiments. This generalized CPA is the basis of our future work on this topic.

  16. Student (Mis)application of Partial Differentiation to Material Properties

    NASA Astrophysics Data System (ADS)

    Bucy, Brandon R.; Thompson, John R.; Mountcastle, Donald B.

    2007-01-01

    Students in upper-level undergraduate thermodynamics courses were asked about the relationship between the complementary partial derivatives of the isothermal compressibility and the thermal expansivity of a substance. Both these material properties can be expressed with first partial derivatives of the system volume. Several of the responses implied difficulty with the notion of variables held fixed in a partial derivative. Specifically, when asked to find the partial derivative of one of these quantities with respect to a variable that was initially held fixed, a common response was that this (mixed second) partial derivative must be zero. We have previously reported other related difficulties in the context of the Maxwell relations, indicating persistent confusion applying partial differentiation to state functions. We present results from student homework and examination questions and briefly discuss an instructional strategy to address these issues.

  17. Partially coherent ultrafast spectrography

    NASA Astrophysics Data System (ADS)

    Bourassin-Bouchet, C.; Couprie, M.-E.

    2015-03-01

    Modern ultrafast metrology relies on the postulate that the pulse to be measured is fully coherent, that is, that it can be completely described by its spectrum and spectral phase. However, synthesizing fully coherent pulses is not always possible in practice, especially in the domain of emerging ultrashort X-ray sources where temporal metrology is strongly needed. Here we demonstrate how frequency-resolved optical gating (FROG), the first and one of the most widespread techniques for pulse characterization, can be adapted to measure partially coherent pulses even down to the attosecond timescale. No modification of experimental apparatuses is required; only the processing of the measurement changes. To do so, we take our inspiration from other branches of physics where partial coherence is routinely dealt with, such as quantum optics and coherent diffractive imaging. This will have important and immediate applications, such as enabling the measurement of X-ray free-electron laser pulses despite timing jitter.

  18. Partially coherent ultrafast spectrography

    PubMed Central

    Bourassin-Bouchet, C.; Couprie, M.-E.

    2015-01-01

    Modern ultrafast metrology relies on the postulate that the pulse to be measured is fully coherent, that is, that it can be completely described by its spectrum and spectral phase. However, synthesizing fully coherent pulses is not always possible in practice, especially in the domain of emerging ultrashort X-ray sources where temporal metrology is strongly needed. Here we demonstrate how frequency-resolved optical gating (FROG), the first and one of the most widespread techniques for pulse characterization, can be adapted to measure partially coherent pulses even down to the attosecond timescale. No modification of experimental apparatuses is required; only the processing of the measurement changes. To do so, we take our inspiration from other branches of physics where partial coherence is routinely dealt with, such as quantum optics and coherent diffractive imaging. This will have important and immediate applications, such as enabling the measurement of X-ray free-electron laser pulses despite timing jitter. PMID:25744080

  19. Partially integrated exhaust manifold

    DOEpatents

    Hayman, Alan W; Baker, Rodney E

    2015-01-20

    A partially integrated manifold assembly is disclosed which improves performance, reduces cost and provides efficient packaging of engine components. The partially integrated manifold assembly includes a first leg extending from a first port and terminating at a mounting flange for an exhaust gas control valve. Multiple additional legs (depending on the total number of cylinders) are integrally formed with the cylinder head assembly and extend from the ports of the associated cylinder and terminate at an exit port flange. These additional legs are longer than the first leg such that the exit port flange is spaced apart from the mounting flange. This configuration provides increased packaging space adjacent the first leg for any valving that may be required to control the direction and destination of exhaust flow in recirculation to an EGR valve or downstream to a catalytic converter.

  20. Partially coherent ultrafast spectrography.

    PubMed

    Bourassin-Bouchet, C; Couprie, M-E

    2015-01-01

    Modern ultrafast metrology relies on the postulate that the pulse to be measured is fully coherent, that is, that it can be completely described by its spectrum and spectral phase. However, synthesizing fully coherent pulses is not always possible in practice, especially in the domain of emerging ultrashort X-ray sources where temporal metrology is strongly needed. Here we demonstrate how frequency-resolved optical gating (FROG), the first and one of the most widespread techniques for pulse characterization, can be adapted to measure partially coherent pulses even down to the attosecond timescale. No modification of experimental apparatuses is required; only the processing of the measurement changes. To do so, we take our inspiration from other branches of physics where partial coherence is routinely dealt with, such as quantum optics and coherent diffractive imaging. This will have important and immediate applications, such as enabling the measurement of X-ray free-electron laser pulses despite timing jitter. PMID:25744080

  1. Management of Chronic Hyperplastic Pulpitis in Mandibular Molars of Middle Aged Adults- A Multidisciplinary Approach

    PubMed Central

    Lingeswaran, Somiya; Ari, Geetha; Thyagarajan, Ramakrishnan; Logaranjani, Anitha

    2016-01-01

    The molar tooth of children and young adults is a common site for chronic hyperplastic pulpitis (pulp polyp). It rarely occurs in middle aged adults. This condition is usually characterized by extensive involvement of the pulp, dictating the extraction of involved tooth. Extraction of permanent molars can lead to transient or permanent malocclusion, aesthetic, phonetic and functional problems. Here we report a case of pulp polyp in mandibular first molar of a 33-year-old woman that grew into the carious cavity. The aim of this case report is to describe the diagnosis of a chronic hyperplastic pulpitis involving the permanent molar as well as to describe its management in order to preserve them as a functional unit of the dentition. PMID:26894192

  2. Identification of a nonsense mutation in the PAX9 gene in molar oligodontia.

    PubMed

    Nieminen, P; Arte, S; Tanner, D; Paulin, L; Alaluusua, S; Thesleff, I; Pirinen, S

    2001-10-01

    Development of dentition is controlled by numerous genes, as has been shown by experimental animal studies and mutations that have been identified by genetic studies in man. Here we report a nonsense mutation in the PAX9 gene that is associated with molar tooth agenesis in a Finnish family. The A340T transversion creates a stop codon at lysine 114, and truncates the coded PAX9 protein at the end of the DNA-binding paired-box. All the affected members of the family were heterozygous for the mutation. The tooth agenesis phenotype involves all permanent second and third molars and most of the first molars and resembles the earlier reported phenotype that was also associated with a PAX9 mutation. The phenotype is presumably a consequence of haploinsufficiency of PAX9. In another Finnish family with molar tooth agenesis, we could not find similar sequence changes in PAX9. PMID:11781684

  3. Simplifying Chemical Reactor Design by using Molar Quantities Instead of Fractional Conversion.

    ERIC Educational Resources Information Center

    Brown, Lee F.; Falconer, John L.

    1987-01-01

    Explains the advantages of using molar quantities in chemical reactor design. Advocates the use of differential versions of reactor mass balances rather than the integrated forms. Provides specific examples and cases to illustrate the principles. (ML)

  4. Accidental Displacement of Third Molar into the Sublingual Space: a Case Report

    PubMed Central

    Garcia, Robson Rodrigues; Botelho, Tessa Lucena; Franco, Ademir; Silva, Rhonan Ferreira

    2014-01-01

    ABSTRACT Background Successful extraction of third molars depends on preoperative diagnosis and planning. Gold standard preoperative examinations are performed through computed tomography, decreasing risks and avoiding potential accidents. The present report highlights the value of preoperative examinations in face of accidentally displaced third molars. Methods An 18-years-old female patient underwent a third mandibular molar extraction with a general dentist. Accidentally, the mandibular left third molar was displaced into the sublingual space, making necessary a second surgical step. The surgery was interrupted and the patient was referred to an expert in maxillofacial surgery. Results After 21 days awaiting an asymptomatic health status, the second surgical step was successfully performed using multislice computed tomography as preoperative imaging guide. Conclusions The present case report highlights the clinical usefulness of imaging planning and informed consents in face of legal and ethic potential complaints. PMID:25386232

  5. Sinus augmentation at the time of molar tooth removal: modification of Jensen technique.

    PubMed

    Block, Michael S

    2015-06-01

    When a maxillary molar tooth needs to be removed, the treatment plan often includes subsequent dental implant placement. However, there may be less than 5mm of bone available in the central fossa region of the proposed implant site. This report describes a technique to use a precise osteotomy within the maxillary molar socket to mobilize a segment of bone and superiorly raise it to provide increased alveolar bone height using grafting. This technique eliminates the need for lateral window surgery. PMID:25659359

  6. Endodontic management of maxillary permanent first molar with 6 root canals: 3 case reports.

    PubMed

    Albuquerque, Denzil Valerian; Kottoor, Jojo; Dham, Sonal; Velmurugan, Natanasabapathy; Abarajithan, Mohan; Sudha, Rajmohan

    2010-10-01

    This article discusses the successful endodontic management of 3 permanent maxillary first molars presenting with the anatomical variation of 3 roots and 6 root canals. A literature review pertaining to the variable root canal morphology of the permanent maxillary first molar is also presented. Modifications in the root canal access preparation and methods for examination of the pulpal floor with the aid of magnification for identification of additional canals are emphasized. PMID:20656533

  7. Apexification of non-vital pre-molar stemming from possible dens evaginatus.

    PubMed

    Asgari, Ali; Kaufman, Elan; Kourtsounis, Paraskevas; Baharestani, Michael

    2009-03-01

    Dens evaginatus is a dental anomaly that occurs more commonly in pre-molar teeth. Although not a cause for alarm in most instances, it can lead to serious consequences if it is damaged. This paper explores the treatment of a necrotic pre-molar with an open apex that caused serious facial swelling in an adolescent patient. It is believed that this swelling was the result of an enamel tubercle, or dens evaginatus, which was knocked off or traumatized. PMID:19418879

  8. Single rooted primary first molar with nonsyndromic hypodontia: A rare case report

    PubMed Central

    Marwah, Nikhil; Goenka, Puneet; Gumber, Parvind

    2015-01-01

    Dental anomalies of number, shape and size are the most common to dental literature, the most common being the agenesis and morphologic dental anomalies. However, very few cases have been reported regarding the presence of single root in primary molars. The purpose of this article was to present a rare case of single root in primary mandibular first molar associated with nonsyndromic hypodontia. PMID:26604513

  9. Root Canal Treatment of a Maxillary Second Molar with Two Palatal Canals: a Case Report

    PubMed Central

    Nabavizadeh, MohammadReza; Abbaszadegan, Abbas; Mirhadi, Hosein; Ghahramani, Yasmin

    2015-01-01

    Careful understanding of internal anatomy of root canal system is crucial for successful endodontic treatment. The presence of two palatal canals in maxillary second molar is unusual but noteworthy as an aid to appropriate diagnosis and treatment. This paper reported a case of a maxillary right second molar with two root canals in the palatal root. The root canal treatment and case management were also explained. PMID:26636127

  10. Unerupted lower third molar extractions and their risks for mandibular fracture.

    PubMed

    Corra, Ana Paula Simes; Faverani, Leonardo Perez; Ramalho-Ferreira, Gabriel; Ferreira, Sabrina; vila Souza, Francisley; de Oliveira Puttini, Igor; Rangel Garcia-Jnior, Idelmo

    2014-05-01

    As every surgical procedure extraction of third molars can result in several complications, among them the mandibular angle fracture. Predisposing factors for fracture should be analyzed during and after the surgery. This paper aims to discuss the predisposing factors to the occurrence of mandibular angle fractures during and after the procedure for third molars extraction, as well as surgical principles to avoid this complication. PMID:24785744

  11. Osteomyelitis of the condyle secondary to pericoronitis of a third molar: a case and literature review.

    PubMed

    Wang, R; Cai, Y; Zhao, Y F; Zhao, J H

    2014-09-01

    In this study, we report a very unusual case of a patient with osteomyelitis of the condyle secondary to pericoronitis of an impacted third molar. The patient was treated by removal of the impacted third molar, opening of the drainage, combined with systemic application of antibiotics for two weeks. This treatment option did not lead to any functional defects or facial asymmetry. The patient fully recovered and the disease did not recur. PMID:24819410

  12. A geometric morphometric analysis of hominin lower molars: Evolutionary implications and overview of postcanine dental variation.

    PubMed

    Gómez-Robles, Aida; Bermúdez de Castro, José María; Martinón-Torres, María; Prado-Simón, Leyre; Arsuaga, Juan Luis

    2015-05-01

    Lower molars have been extensively studied in the context of hominin evolution using classic and geometric morphometric analyses, 2D and 3D approaches, evaluations of the external (outer enamel surface) and internal anatomy (dentine, pulp chamber, and radicular canals), and studies of the crown and root variation. In this study, we present a 2D geometric morphometric analysis of the crown anatomy of lower first, second, and third molars of a broad sample of hominins, including Pliocene and Lower, Middle, and Upper Pleistocene species coming from Africa, Asia, and Europe. We show that shape variability increases from first to second and third molars. While first molars tend to retain a relatively stable 5-cusped conformation throughout the hominin fossil record, second and third molars show marked distal reductions in later Homo species. This trend to distal reduction is similar to that observed in previous studies of premolars and upper second and third molars, and points to a correlated reduction of distal areas across the whole postcanine dentition. Results on lower molar variation, as well as on other postcanine teeth, show certain trends in European Pleistocene populations from the Atapuerca sites. Middle Pleistocene hominins from Sima de los Huesos show Neanderthal affinities and strong dental reduction, especially in the most distal molars. The degree of dental reduction in this population is stronger than that observed in classic Neanderthals. Homo antecessor hominins from Gran Dolina-TD6 have primitive lower teeth that contrast with their more derived upper teeth. The evolutionary implications of these dental affinities are discussed in light of recent paleogenetic studies. PMID:25840859

  13. Spectrophotometric color evaluation of permanent incisors, canines and molars. A cross-sectional clinical study

    PubMed Central

    POP-CIUTRILA, IOANA-SOFIA; COLOSI, HORATIU ALEXANDRU; DUDEA, DIANA; BADEA, MANDRA EUGENIA

    2015-01-01

    Background and aims An accurate color reproduction represents the final validation level of an esthetic anterior or posterior restoration. The aim of this study was to evaluate the color of permanent maxillary incisors, canines and molars, using a clinical spectrophotometer. Methods The Vita Easyshade Advance 4.0® intraoral spectrophotometer was used by one clinician to determine the color of 369 permanent maxillary incisors, canines and molars. The best matches to Vitapan Classical® and 3D-Master® shade guides were recorded. A one-way analysis of variance and Kruskal-Wallis test were used to compare L*, a*, b*, c* and h* color coordinates among the 3 types of teeth. Differences between the mean values of all color coordinates were evaluated by use of Bonferroni corrections. Color difference (ΔE*) between incisors, canines and molars was calculated from ΔL*, Δa* and Δb* data and the results were compared to ΔE*=3.3 acceptability threshold. Results Except for Δa* and Δh* between canines and molars, statistically significant differences among the mean differences of all color coordinates were found when the 3 types of teeth were compared by pairs. The most frequently measured shades were A1 (48.4%), respectively 1M1 (31.5%) for incisors, B3 (36.6%), respectively 2M3 (39.8%) for canines and B3 (44.7%), respectively 2M3 (52%) for molars. Incisors had the highest lightness values, followed by canines and molars. Molars were the most chromatic with the highest a* and b* values. Conclusions Despite the limitations of this study, color differences among incisors, canines and molars were found to be statistically significant, above the clinical acceptability threshold established. In conclusion, successful esthetic restorations of permanent teeth of the same patient need an individual color assessment and reproduction of every type of tooth. PMID:26733753

  14. Agenesis of premolar associated with submerged primary molar and a supernumerary premolar: An unusual case report

    PubMed Central

    Nirmala, S. V. S. G.; Sandeep, C.; Sivakumar, N.; Babu, M. S.; Lalitha, V.

    2012-01-01

    The combination of submerged primary molar, agenesis of permanent successor with a supernumerary in the same place is very rare. The purpose of this article is to report a case of submerged mandibular left second primary molar with supernumerary tooth in the same region along with agenesis of second premolar in an 11-year-old girl, its possible etiological factors, and a brief discussion on treatment options. PMID:22629079

  15. Occlusal morphology of permanent mandibular first and second molars in Gujarati population

    PubMed Central

    Dholia, Bhavik; Manjunatha, Bhari Sharanesha

    2015-01-01

    Background: Dental identification has been used since long time for disaster victim identification protocol. There is a difference of opinion regarding whether ethnicity influences dental morphology or not. Few studies have shown the associations between these dental features and crown traits in humans using quantitative methods. The present study is an attempt to find correlation of occlusal morphology of Gujarati population with forensic Odontology. Aim: To study different occlusal morphology of permanent mandibular first and second molars in Gujarati Population. Materials and Methods: This study comprised of a total of 100 participants of Gujarati origin, selected by random sampling method. Total number of cusps and groove patterns of mandibular first and second molar were examined clinically and photographs of the same were taken. A descriptive statistics, Chi-square test and Student t-test were used for analysis of data. Results: Mandibular first molar with 5 cusps in 71%, 4 cusps in 18% and 6 cusps in 11% were noted in the study. Mandibular first molars with “+” groove pattern in 39.5% and “Y” groove pattern in 60.5% were recorded. Mandibular second molar with 5 cusps in 6.5% and 4 cusps in 93.5% were recorded in the study. Mandibular second molars with “+” groove pattern in 93.5% and “Y” groove pattern in 6.5% were recorded. Conclusion: The most common occlusal morphology in permanent mandibular first molar is “5 cusp” and “Y” groove pattern in about 47% and for second molar is “4 cusp” and “+” groove pattern in 88.5% of Gujarati population. It may be concluded that variation in degree of expression and frequency of teeth in dentitions of different populations is different, which may help in forensic identification. PMID:26005303

  16. Comparison of sexual dimorphism of permanent mandibular canine with mandibular first molar by odontometrics

    PubMed Central

    Agrawal, Aditi; Manjunatha, Bhari Shranesha; Dholia, Bhavik; Althomali, Yousef

    2015-01-01

    Background and Objectives: Sexual dimorphism is one of important tool of forensic science. The objective of this study is to assess the dimorphic status of mesio-distal (MD) and bucco-lingual (BL) diameter of mandibular canine with mandibular first molar among the students of dental college. This study is of definite significance as sex chromosomes and hormonal production influenced tooth morphology. Materials and Methods: The descriptive study adopted the purposive sampling technique, of 50 male and 50 female aged 17-25 years, using study casts for mesio-distal and bucco-lingual dimensions of mandibular canine with mandibular first molar were taken using digital Vernier caliper. The data obtained were subjected to statistical analysis using descriptive statistics and t-test to compare MD and BL dimensions in male and female populations and P ≤ 0.05 was found statistically significant. Results: Sexual dimorphism can be predicted by measuring mesiodistal dimension of mandibular canine and mandibular first molar. The left mandibular canine showed more sexual dimorphism (12.66%) in comparison to left mandibular first molar (0.824%) only. Right mandibular canine showed greater dimorphism in MD dimensions (10.94%) in comparison to right mandibular first molar (6.96%). In bucco-lingual dimensions mandibular canine showed less variability when compared with mandibular first molar, thus our study showed more significance on mesio-distal dimensions of both teeth. Conclusion: The present study concludes statistically significant sexual dimorphism in mandibular canine over mandibular first molar on study casts. The MD dimensions in mandibular canine and mandibular first molar can help in determining sex and identification of unknown person. PMID:26816466

  17. Root Canal Treatment of a Maxillary Second Molar with Two Palatal Canals: a Case Report.

    PubMed

    Nabavizadeh, MohammadReza; Abbaszadegan, Abbas; Mirhadi, Hosein; Ghahramani, Yasmin

    2015-12-01

    Careful understanding of internal anatomy of root canal system is crucial for successful endodontic treatment. The presence of two palatal canals in maxillary second molar is unusual but noteworthy as an aid to appropriate diagnosis and treatment. This paper reported a case of a maxillary right second molar with two root canals in the palatal root. The root canal treatment and case management were also explained. PMID:26636127

  18. Effects of first premolar extraction on maxillary and mandibular third molar angulation after orthodontic therapy

    PubMed Central

    Gohilot, Avinash; Pradhan, Tejashri; Keluskar, Kanhoba Mahabaleshwar

    2012-01-01

    Background/Aims To compare the change in the angulation of developing mandibular third molar in both first premolar extraction and non-extraction cases and to determine whether premolar extraction results in a more mesial movement of the mandibular buccal segment and causes favorable rotational changes in the mandibular third molar tilt, which can enhance later eruption of the third molars. Materials and methods Pretreatment (T1) and post treatment (T2) panoramic radiographs were taken of 25 subjects (age 14–19 years) who had been treated by the extraction of all the first premolars and 25 subjects who had been treated with non-extraction. The horizontal reference plane was used to measure and compare the changes in the angles of the developing mandibular third molars. Results The mean uprighting of the maxillary third molars seen in the extraction group was 4 ± 9° on the left side and −17 ± 13° on the right side following treatment (T2 _ T1). For the non-extraction group the mean difference was −16 ± 12° on the left side and 2 ± 13° on the right side. There was a statistically significant difference between the groups (P _ 0.021 on the right side and P _ 0.041 on the left side). Mandibular 3rd molars in extraction group showed no statistical significant change in the angulation. Conclusion Premolar extractions had a positive influence on the developing maxillary third molar angulations both on right and left. Mandibular 3rd molar have shown change in the angulation but not statistically significant. Non-extraction therapy did not have any adverse effect. PMID:25737843

  19. Recommendations for Third Molar Removal: A Practice-Based Cohort Study

    PubMed Central

    Cunha-Cruz, Joana; Rothen, Marilynn; Spiekerman, Charles; Drangsholt, Mark; McClellan, Lyle; Huang, Greg J.

    2014-01-01

    Objectives We investigated general dentists reasons for recommending removal or retention of third molars and whether patients adhered to dentists recommendations. Methods In a 2-year prospective cohort study (20092011) in the Pacific Northwest, we followed 801 patients aged 16 to 22 years from 50 general dental practices. Generalized estimating equations logistic regressions related patient and dentist characteristics to dentists recommendations to remove third molars and to patient adherence. Results General dentists recommended removal of 1683 third molars from 469 (59%) participants, mainly to prevent future problems (79%) or because a third molar had an unfavorable orientation or was unlikely to erupt (57%). Dentists recommended retention and monitoring of 1244 third molars from 366 (46%) participants, because it was too early to decide (73%), eruption path was favorable (39%), or space for eruption was sufficient (26%). When dentists recommended removal, 55% of participants adhered to this recommendation during follow-up, and the main reason was availability of insurance (88%). Conclusions General dentists frequently recommended removal of third molars for reasons not related to symptoms or pathology, but rather to prevent future problems. PMID:24524519

  20. A Novel Chitin Binding Crayfish Molar Tooth Protein with Elasticity Properties

    PubMed Central

    Tynyakov, Jenny; Bentov, Shmuel; Abehsera, Shai; Khalaila, Isam; Manor, Rivka; Katzir Abilevich, Lihie; Weil, Simy; Aflalo, Eliahu D.; Sagi, Amir

    2015-01-01

    The molar tooth of the crayfish Cherax quadricarinatus is part of the mandible, and is covered by a layer of apatite (calcium phosphate). This tooth sheds and is regenerated during each molting cycle together with the rest of the exoskeleton. We discovered that molar calcification occurs at the pre-molt stage, unlike calcification of the rest of the new exoskeleton. We further identified a novel molar protein from C. quadricarinatus and cloned its transcript from the molar-forming epithelium. We termed this protein Cq-M13. The temporal level of transcription of Cq-M13 in an NGS library of molar-forming epithelium at different molt stages coincides with the assembly and mineralization pattern of the molar tooth. The predicted protein was found to be related to the pro-resilin family of cuticular proteins. Functionally, in vivo silencing of the transcript caused molt cycle delay and a recombinant version of the protein was found to bind chitin and exhibited elastic properties. PMID:26010981

  1. A reliable method for evaluating upper molar distalization: Superimposition of three-dimensional digital models

    PubMed Central

    Nalcaci, Ruhi; Bicakci, Ali Altug; Ozturk, Firat; Babacan, Hasan

    2015-01-01

    Objective The aim of this study was to evaluate the reliability of measurements obtained after the superimposition of three-dimensional (3D) digital models by comparing them with those obtained from lateral cephalometric radiographs and photocopies of plaster models for the evaluation of upper molar distalization. Methods Data were collected from plaster models and lateral cephalometric radiographs of 20 Class II patients whose maxillary first molars were distalized with an intraoral distalizer. The posterior movements of the maxillary first molars were evaluated using lateral cephalometric radiographs (group CP), photocopies of plaster models (group PH), and digitized 3D models (group TD). Additionally, distalization and expansion of the other teeth and the degrees of molar rotation were measured in group PH and group TD and compared between the two groups. Results No significant difference was observed regarding the amount of molar distalization among the three groups. A comparison of the aforementioned parameters between group PH and group TD did not reveal any significant difference. Conclusions 3D digital models are reliable to assess the results of upper molar distalization and can be considered a valid alternative to conventional measurement methods. PMID:25798414

  2. Root resorption of primary molars without successor teeth. An experimental study in the beagle dog.

    PubMed

    Lin, Bi-Chen; Zhao, Yu-Ming; Yang, Jie; Ge, Li-Hong

    2012-04-01

    Tooth agenesis is a common craniofacial congenital malformation in humans, but little is known about the mechanisms of root resorption in this condition. The purpose of this study was to investigate the mechanisms of root resorption in primary molars without successors. An animal model without permanent tooth germs was established by surgery in beagles. The times of onset of primary molar root resorption, with and without successors, were compared. The distribution of immune cells, odontoclasts, and their activating factors were determined by histochemistry and immunohistochemistry. Root resorption of primary mandibular molars without successors began later than physiological resorption. In primary molars without permanent germs, odontoclasts and immune cells were present mainly in the apical pulp at the start of root resorption, whereas in control teeth receptor activator of nuclear factor-?B ligand (RANKL)-positive cells were found mainly in the region of the periodontal ligament. CD14(+) and CD3(+) cells were found in both the pulp and the periodontal ligament region. These results suggest that the dental pulp of primary molars, as well as immune cells, may play an important role in root resorption in primary molars without permanent tooth germs. PMID:22409221

  3. Sharp mandibular bone irregularities after lower third molar extraction: Incidence, clinical features and risk factors

    PubMed Central

    Alves-Pereira, Daniela; Valmaseda-Castellón, Eduard; Laskin, Daniel M.; Berini-Aytés, Leonardo; Gay-Escoda, Cosme

    2013-01-01

    Objectives: The purpose of this study was to determine the incidence and clinical symptoms associated with sharp mandibular bone irregularities (SMBI) after lower third molar extraction and to identify possible risk factors for this complication. Study Design: A mixed study design was used. A retrospective cohort study of 1432 lower third molar extractions was done to determine the incidence of SMBI and a retrospective case-control study was done to determine potential demographic and etiologic factors by comparing those patients with postoperative SMBI with controls. Results: Twelve SMBI were found (0.84%). Age was the most important risk factor for this complication. The operated side and the presence of an associated radiolucent image were also significantly related to the development of mandibular bone irregularities. The depth of impaction of the tooth might also be an important factor since erupted or nearly erupted third molars were more frequent in the SMBI group. Conclusions: SMBI are a rare postoperative complication after lower third molar removal. Older patients having left side lower third molars removed are more likely to develop this problem. The treatment should be the removal of the irregularity when the patient is symptomatic. Key words:Third molar, postoperative complication, bone irregularities, age. PMID:23524429

  4. Melancholia and partial insanity.

    PubMed

    Jackson, S W

    1983-04-01

    In the medical literature of the eighteenth century melancholia came to be defined as partial insanity. Seventeenth-century English law introduced the term and influenced later forensic concerns about the concept. But the history of melancholia reveals a gradual development of such a concept of limited derangement associated with the delusions usually cited in accounts of this disease. In the early nineteenth century the relationship of melancholia and this concept weakened and was gradually abandoned, the content of the syndrome of melancholia was reduced, and out of this complex process emerged the notion of monomania. PMID:11608558

  5. Improving the developability profile of pyrrolidine progesterone receptor partial agonists

    SciTech Connect

    Kallander, Lara S.; Washburn, David G.; Hoang, Tram H.; Frazee, James S.; Stoy, Patrick; Johnson, Latisha; Lu, Qing; Hammond, Marlys; Barton, Linda S.; Patterson, Jaclyn R.; Azzarano, Leonard M.; Nagilla, Rakesh; Madauss, Kevin P.; Williams, Shawn P.; Stewart, Eugene L.; Duraiswami, Chaya; Grygielko, Eugene T.; Xu, Xiaoping; Laping, Nicholas J.; Bray, Jeffrey D.; Thompson, Scott K.

    2010-09-17

    The previously reported pyrrolidine class of progesterone receptor partial agonists demonstrated excellent potency but suffered from serious liabilities including hERG blockade and high volume of distribution in the rat. The basic pyrrolidine amine was intentionally converted to a sulfonamide, carbamate, or amide to address these liabilities. The evaluation of the degree of partial agonism for these non-basic pyrrolidine derivatives and demonstration of their efficacy in an in vivo model of endometriosis is disclosed herein.

  6. Is Titan Partially Differentiated?

    NASA Astrophysics Data System (ADS)

    Mitri, G.; Pappalardo, R. T.; Stevenson, D. J.

    2009-12-01

    The recent measurement of the gravity coefficients from the Radio Doppler data of the Cassini spacecraft has improved our knowledge of the interior structure of Titan (Rappaport et al. 2008 AGU, P21A-1343). The measured gravity field of Titan is dominated by near hydrostatic quadrupole components. We have used the measured gravitational coefficients, thermal models and the hydrostatic equilibrium theory to derive Titan's interior structure. The axial moment of inertia gives us an indication of the degree of the interior differentiation. The inferred axial moment of inertia, calculated using the quadrupole gravitational coefficients and the Radau-Darwin approximation, indicates that Titan is partially differentiated. If Titan is partially differentiated then the interior must avoid melting of the ice during its evolution. This suggests a relatively late formation of Titan to avoid the presence of short-lived radioisotopes (Al-26). This also suggests the onset of convection after accretion to efficiently remove the heat from the interior. The outer layer is likely composed mainly of water in solid phase. Thermal modeling indicates that water could be present also in liquid phase forming a subsurface ocean between an outer ice I shell and a high pressure ice layer. Acknowledgments: This work was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  7. Decision making in third molar surgery: a survey of Brazilian oral and maxillofacial surgeons.

    PubMed

    Camargo, Igor Batista; Melo, Auremir Rocha; Fernandes, Andr Vajgel; Cunningham, Larry L; Laureano Filho, Jos R; Van Sickels, Joseph E

    2015-08-01

    This study was designed to evaluate the variations in decision making among Brazilian oral and maxillofacial surgeons (OMFS) and trainees in relation to third molar surgery. A survey on 18 diverse clinical situations related to the assessment and treatment of the third molar surgeries was conducted during the 20th Brazilian National OMFS meeting. Participants were divided into three groups according to their level of training. Another variable studied was length of experience. Correlation between the question answers and the variables was analysed using the chi-square test and the f test. The mean age of participants was 32.68 years, and their mean length of experience was 5.24 years. There were no statistical differences between the level of training and number of years of experience and the responses to 15 of the 18 questions on clinical situations. However, differences were found in responses to prophylactic extraction of asymptomatic third molars, use of non-steriodal anti-inflammatory drugs (NSAIDs) during the preoperative surgical period and the use of additional imaging to plan extractions. The group with shorter time of experience (3.8 3.94 years) tended to recommend extractions of asymptomatic third molars more frequently compared with the more experienced surgeons (P = 0.041). More experienced surgeons used NSAIDs in the preoperative surgical period, whereas the majority of the youngest surgeons (4.1 5.96 years of experience) did not (P = 0.0042). The certificated trained and in practice group tended to treat deep lower third molar impactions based on the findings of a panoramic radiograph, without obtaining additional imaging [cone beam computed tomography (CBCT)] before treatment (P = 0.0132). Decision making regarding third molar treatment differs according to the level of training and is influenced by the number of years of experience. Therefore, further continuous education programmes in this area are warranted to make recommendations regarding third molars consistent with the current literature. PMID:25879578

  8. Conventional root canal therapy of C-shaped mandibular second molar. A case report.

    PubMed

    Lynn, Evan A

    2006-11-01

    The C-shaped root canal system and treatment implications were first described by Cooke and Cox in 1979. C-shaped canals are most frequently found in mandibular second molars, but they can occur in any mandibular molar, and they have been reported in maxillary molars as well. C-shaped mandibular molars are characterized by a C-shaped groove that connects one or more root canals. This groove can occur anywhere along the root canal system, making it difficult to diagnose and treat. A C-shaped root canal system may appear completely normal at the level of the pulp chamber but can begin to manifest itself in the middle or apical one-third. Furthermore, C-shaped canals are challenging if not impossible to predict radiographically. C-shaped canals in mandibular second molars are found most frequently in the Chinese population, with reports showing up to a 31.5% incidence, as compared to an approximate 7% incidence in the general population. This case report demonstrates an incidence of a C-shaped canal that was unable to be detected radiographically and which contained three separate root canals that communicated in the apical one-third of the root canal system. Canal orifices were located approximately 2 mm below the level of the CEJ, which is in agreement with a recent micro-computed tomography study of C-shaped mandibular molars that found 98% of all C-shaped molars studied had orifices located 1 mm to 3 mm below the CEJ. The CT study also found that all C-shaped canals contained fused roots and confirmed previous findings that the C-shape configuration varies greatly throughout the length of the canal. PMID:17203853

  9. Dentoskeletal effects induced by rapid molar distalization with the first class appliance.

    PubMed

    Fortini, Arturo; Lupoli, Massimo; Giuntoli, Fabio; Franchi, Lorenzo

    2004-06-01

    The purpose of this study was to evaluate the treatment effects of the first class appliance (FCA; Leone, Firenze, Italy), a new intraoral device for unilateral or bilateral rapid molar distalizaton. A retrospective study was conducted to compare the predistalization and postdistalization cephalograms of 17 patients (10 male, 7 female) with Class II malocclusions treated with the FCA. Mean age at the start of treatment was 13 years 4 months. The FCA produced rapid molar distalization, and the bilateral Class II molar relationship was corrected in 2.4 months, on average. Maxillary molar distalization contributed to 70% of the space created anterior to the first molars; 30% of the space was due to reciprocal anchorage loss of the maxillary second premolars. The maxillary first molars showed a significant distalization of 4.0 mm, associated with a significant distal axial incline of 4.6 degrees and a significant extrusion of 1.2 mm. As for anchorage loss, the second premolars exhibited a significant mesial movement of 1.7 mm, associated with a significant mesial axial incline of 2.2 degrees and a nonsignificant extrusion of 1.0 mm. In the anterior region, a significant mesial movement of the maxillary incisor of 1.3 mm was associated with a significant incisor proclination (2.6 degrees ) and a significant increase in overjet (1.2 mm). No significant changes in either sagittal or vertical skeletal relationships were observed. The results suggest that the FCA is an efficient and reliable device for distalizing the maxillary permanent first molars. PMID:15179394

  10. Statistical genetic comparison of two techniques for assessing molar crown size in pedigreed baboons.

    PubMed

    Hlusko, Leslea J; Weiss, Kenneth M; Mahaney, Michael C

    2002-02-01

    Dental anthropologists and paleoanthropologists commonly use an estimated molar crown area (mesiodistal length multiplied by buccolingual width) to describe and compare individuals, populations, and species. Advances in digital imaging now allow researchers to measure the actual crown area of a molar in an occlusal two-dimensional plane. Because error is reduced by this more accurate measurement, actual crown area is thought to be a better representation of the mechanisms that determine tooth crown size, meriting the additional time required to collect it. We tested this assumption by estimating the heritability of both these measurements for the second left mandibular molar from a sample of individuals (n = 332) from a captive breeding colony of baboons. Heritability estimates of both the actual and estimated crown areas of molars are approximately 0.83. Therefore, both measurements are informative as population descriptors, with no significant difference between the accuracy of either to reflect additive genetic contributions to molar crown size. This is fortunate, because genetic studies and inference can be based on estimated areas rather than actual crown area. The heritability estimates for mesiodistal length and buccolingual width are both substantial but lower: approximately 0.67 and approximately 0.73, respectively. The best fitting models in these analyses show that sex, body size, and subspecific affinity differentially affect molar length and width. We interpret these results to suggest that potentially some of the genetics underlying these covariates also underlie tooth size. As such, measurements designed to describe molar crown size are useful for general descriptive purposes, but do not conform to the assumption of independence inherent in phylogenetic analyses, such as cladistics (Hennig [1966] Phylogenetic Systematics. Urbana: University of Illinois Press). Therefore, if variables like actual crown area and estimated crown area are to be used in phylogenetic parsimony analyses, we suggest that researchers account for the effects of covariates such as sex and body size in their analyses. PMID:11815951

  11. Analysis and evaluation of relative positions of mandibular third molar and mandibular canal impacts

    PubMed Central

    Kim, Hang-Gul

    2014-01-01

    Objectives This study used cone-beam computed tomography (CBCT) images to categorize the relationships between the mandibular canal and the roots and investigated the prevalence of nerve damage. Materials and Methods Through CBCT images, contact and three-dimensional positional relationships between the roots of the mandibular third molar and the mandibular canal were investigated. With this data, prevalence of nerve damage according to the presence of contact and three-dimensional positional relationships was studied. Other factors that affected the prevalence of nerve damage were also investigated. Results When the mandibular third molar and the mandibular canal were shown to have direct contact in CBCT images, the prevalence of nerve damage was higher than in other cases. Also, in cases where the mandibular canal was horizontally lingual to the mandibular third molar and the mandibular canal was vertically at the cervical level of the mandibular third molar, the prevalence of nerve damage was higher than in opposite cases. The percentage of mandibular canal contact with the roots of the mandibular third molar was higher when the mandibular canal was horizontally lingual to the mandibular third molar. Finally, the prevalence of nerve damage was higher when the diameter of the mandibular canal lumen suddenly decreased at the contact area between the mandibular canal and the roots, as shown in CBCT images. Conclusion The three-dimensional relationship of the mandibular third molar and the mandibular canal can help predict nerve damage and can guide patient expectations of the possibility and extent of nerve damage. PMID:25551092

  12. A crayfish molar tooth protein with putative mineralized exoskeletal chitinous matrix properties.

    PubMed

    Tynyakov, Jenny; Bentov, Shmuel; Abehsera, Shai; Yehezkel, Galit; Roth, Ziv; Khalaila, Isam; Weil, Simy; Berman, Amir; Plaschkes, Inbar; Tom, Moshe; Aflalo, Eliahu D; Sagi, Amir

    2015-11-01

    Some crustaceans possess exoskeletons that are reinforced with calcium carbonate. In the crayfish Cherax quadricarinatus, the molar tooth, which is part of the mandibular exoskeleton, contains an unusual crystalline enamel-like apatite layer. As this layer resembles vertebrate enamel in composition and function, it offers an interesting example of convergent evolution. Unlike other parts of the crayfish exoskeleton, which is periodically shed and regenerated during the molt cycle, molar mineral deposition takes place during the pre-molt stage. The molar mineral composition transforms continuously from fluorapatite through amorphous calcium phosphate to amorphous calcium carbonate and is mounted on chitin. The process of crayfish molar formation is entirely extracellular and presumably controlled by proteins, lipids, polysaccharides, low-molecular weight molecules and calcium salts. We have identified a novel molar protein termed Cq-M15 from C. quadricarinatus and cloned its transcript from the molar-forming epithelium. Its transcript and differential expression were confirmed by a next-generation sequencing library. The predicted acidic pI of Cq-M15 suggests its possible involvement in mineral arrangement. Cq-M15 is expressed in several exoskeletal tissues at pre-molt and its silencing is lethal. Like other arthropod cuticular proteins, Cq-M15 possesses a chitin-binding Rebers-Riddiford domain, with a recombinant version of the protein found to bind chitin. Cq-M15 was also found to interact with calcium ions in a concentration-dependent manner. This latter property might make Cq-M15 useful for bone and dental regenerative efforts. We suggest that, in the molar tooth, this protein might be involved in calcium phosphate and/or carbonate precipitation. PMID:26385331

  13. Precision of marginal adaptation of the incisor and molar Procera allceram crown copings.

    PubMed

    Pilathadka, S; Slezk, R; Srinivasan, V; Ivanckov, R

    2008-01-01

    The primary objective of this in vitro study was to compare the absolute marginal discrepancy (AMD) of CAD/CAM produced Procera AllCeram crown copings, fabricated on die stone master models of two different tooth groups, incisor and molar. Two maxillary central incisors and two first molars typodont teeth were prepared with 0.8 mm of circumferential chamfer, duplicated 9 times to obtain 36 die stone models and allotted into three groups of 12 models (incisors = 6 & molars = 6). Procera AllCeram 0.6 mm copings were fixed with zinc phosphate (AZ), glass ionomer (AG) and resin (AR) cement accordingly under 50 N static finger force. The AMDs were measured using the scanning electron microscope (SEM) on four axial walls with 4 measurements on each wall to obtain 16 readings for one tooth. Statistical analysis of the data was performed using the non-parametric test of Kruskal-Wallis and Mann-Whitney test. The analysis did not find any significant differences in the mean AMD of incisor and molar crown copings, and in different axial surfaces too (p < or = 0.05). Recorded mean AMD of incisor copings were AZ group 59 microm, AG 37.9 microm, and AR 44.4 microm and molar copings were AZ 48.8 microm, AG 27 microm, and AR 50.2 microm. It can be concluded that AMD of Procera AllCeram copings were within accepted level of 100 microm. Incisors showed higher AMD than molars. Molars demonstrated the higher AMD on mid-distal and mid-lingual surfaces whereas for incisor it was mid-buccal and mid-lingual surface. PMID:19097392

  14. Applications of partially quenched chiral perturbation theory

    SciTech Connect

    Golterman, M.F.; Leung, K.C.

    1998-05-01

    Partially quenched theories are theories in which the valence- and sea-quark masses are different. In this paper we calculate the nonanalytic one-loop corrections of some physical quantities: the chiral condensate, weak decay constants, Goldstone boson masses, B{sub K}, and the K{sup +}{r_arrow}{pi}{sup +}{pi}{sup 0} decay amplitude, using partially quenched chiral perturbation theory. Our results for weak decay constants and masses agree with, and generalize, results of previous work by Sharpe. We compare B{sub K} and the K{sup +} decay amplitude with their real-world values in some examples. For the latter quantity, two other systematic effects that plague lattice computations, namely, finite-volume effects and unphysical values of the quark masses and pion external momenta, are also considered. We find that typical one-loop corrections can be substantial. {copyright} {ital 1998} {ital The American Physical Society}

  15. Caries management strategies for primary molars: 1-yr randomized control trial results.

    PubMed

    Santamaria, R M; Innes, N P T; Machiulskiene, V; Evans, D J P; Splieth, C H

    2014-11-01

    Minimal invasive approaches to managing caries, such as partial caries removal techniques, are showing increasing evidence of improved outcomes over the conventional complete caries removal. There is also increasing interest in techniques where no caries is removed. We present the 1-yr results of clinical efficacy for 3 caries management options for occlusoproximal cavitated lesions in primary molars: conventional restorations (CR; complete caries removal and compomer restoration), Hall technique (HT; no caries removal, sealing in with stainless steel crowns), and nonrestorative caries treatment (NRCT; no caries removal, opening up the cavity, teaching brushing and fluoride application). In sum, 169 children (3-8 yr old; mean, 5.56 1.45 yr) were enrolled in this secondary care-based, 3-arm, parallel-group, randomized clinical trial. Treatments were carried out by specialist pediatric dentists or postgraduate trainees. One lesion per child received CR, HT, or NRCT. Outcome measures were clinical failure rates, grouped as minor failure (restoration loss/need for replacement, reversible pulpitis, caries progression, etc.) and major failure (irreversible pulpitis, abscess, etc.). There were 148 children (87.6%) with a minimum follow-up of 11 mo (mean, 12.23 0.98 mo). Twenty teeth were recorded as having at least 1 minor failure: NRCT, n = 8 (5%); CR, n = 11 (7%); HT, n = 1 (1%) (p = .002, 95% CI = 0.001 to 0.003). Only the comparison between NRCT and CR showed no significant difference (p = .79, 95% CI = 0.78 to 0.80). Nine (6%) experienced at least 1 major failure: NRCT, n = 4 (2%); CR, n = 5 (3%); HT, n = 0 (0%) (p = .002, 95% CI = 0.001 to 0.003). Individual comparison of NRCT and CR showed no statistically significant difference in major failures (p = .75, 95% CI = 0.73 to 0.76). Success and failure rates were not significantly affected by pediatric dentists' level of experience (p = .13, 95% CI = 0.12 to 0.14). The HT was significantly more successful clinically than NRCT and CR after 1 yr, while pairwise analyses showed comparable results for treatment success between NRCT and CR (ClinicalTrials.gov NCT01797458). PMID:25216660

  16. Isotropic finite volume discretization

    NASA Astrophysics Data System (ADS)

    Shukla, Ratnesh K.; Giri, Pritam

    2014-11-01

    Finite volume methods traditionally employ dimension by dimension extension of the one-dimensional reconstruction and averaging procedures to achieve spatial discretization of the governing partial differential equations on a structured Cartesian mesh in multiple dimensions. This simple approach based on tensor product stencils introduces an undesirable grid orientation dependence in the computed solution. The resulting anisotropic errors lead to a disparity in the calculations that is most prominent between directions parallel and diagonal to the grid lines. In this work we develop isotropic finite volume discretization schemes which minimize such grid orientation effects in multidimensional calculations by eliminating the directional bias in the lowest order term in the truncation error. Explicit isotropic expressions that relate the cell face averaged line and surface integrals of a function and its derivatives to the given cell area and volume averages are derived in two and three dimensions, respectively. It is found that a family of isotropic approximations with a free parameter can be derived by combining isotropic schemes based on next-nearest and next-next-nearest neighbors in three dimensions. Use of these isotropic expressions alone in a standard finite volume framework, however, is found to be insufficient in enforcing rotational invariance when the flux vector is nonlinear and/or spatially non-uniform. The rotationally invariant terms which lead to a loss of isotropy in such cases are explicitly identified and recast in a differential form. Various forms of flux correction terms which allow for a full recovery of rotational invariance in the lowest order truncation error terms, while preserving the formal order of accuracy and discrete conservation of the original finite volume method, are developed. Numerical tests in two and three dimensions attest the superior directional attributes of the proposed isotropic finite volume method. Prominent anisotropic errors, such as spurious asymmetric distortions on a circular reaction-diffusion wave that feature in the conventional finite volume implementation are effectively suppressed through isotropic finite volume discretization. Furthermore, for a given spatial resolution, a striking improvement in the prediction of kinetic energy decay rate corresponding to a general two-dimensional incompressible flow field is observed with the use of an isotropic finite volume method instead of the conventional discretization.

  17. The influence of surface state and saturation state on the dissolution kinetics of biogenic aragonite in seawater

    USGS Publications Warehouse

    Acker, James G.; Byrne, R.H.

    1989-01-01

    Uses several realistic partial molar volume changes (??V) for aragonite dissolution in seawater. Indicates that the molar volume change for aragonite dissolution is within the bounds -37 cm 3/mole ?????V ??? -39.5 cm3/mole. -from Authors

  18. Impact of the lower third molar presence and position on the fragility of mandibular angle and condyle: A Three-dimensional finite element study.

    PubMed

    Antic, Svetlana; Vukicevic, Arso M; Milasinovic, Marko; Saveljic, Igor; Jovicic, Gordana; Filipovic, Nenad; Rakocevic, Zoran; Djuric, Marija

    2015-07-01

    The aim of the present study was to investigate the influences of the presence and position of a lower third molar (M3) on the fragility of mandibular angle and condyle, using finite element analysis. From computed tomographic scans of a human mandible with normally erupted M3, two additional virtual models were generated: a mandibular model with partially impacted M3 and a model without M3. Two cases of impact were considered: a frontal and a lateral blow. The results are based on the chromatic analysis of the distributed von Mises and principal stresses, and calculation of their failure indices. In the frontal blow, the angle region showed the highest stress in the case with partially impacted M3, and the condylar region in the case without M3. Compressive stresses were dominant but caused no failure. Tensile stresses were recorded in the retromolar areas, but caused failure only in the case with partially impacted M3. In the lateral blow, the stress concentrated at the point of impact, in the ipsilateral and contralateral angle and condylar regions. The highest stresses were recorded in the case with partially impacted M3. Tensile stresses caused the failure on the ipsilateral side, whereas compressive stresses on the contralateral side. PMID:25939313

  19. Partially segmented deformable mirror

    DOEpatents

    Bliss, E.S.; Smith, J.R.; Salmon, J.T.; Monjes, J.A.

    1991-05-21

    A partially segmented deformable mirror is formed with a mirror plate having a smooth and continuous front surface and a plurality of actuators to its back surface. The back surface is divided into triangular areas which are mutually separated by grooves. The grooves are deep enough to make the plate deformable and the actuators for displacing the mirror plate in the direction normal to its surface are inserted in the grooves at the vertices of the triangular areas. Each actuator includes a transducer supported by a receptacle with outer shells having outer surfaces. The vertices have inner walls which are approximately perpendicular to the mirror surface and make planar contacts with the outer surfaces of the outer shells. The adhesive which is used on these contact surfaces tends to contract when it dries but the outer shells can bend and serve to minimize the tendency of the mirror to warp. 5 figures.

  20. Partially segmented deformable mirror

    DOEpatents

    Bliss, Erlan S. (Danville, CA); Smith, James R. (Livermore, CA); Salmon, J. Thaddeus (Livermore, CA); Monjes, Julio A. (San Ramon, CA)

    1991-01-01

    A partially segmented deformable mirror is formed with a mirror plate having a smooth and continuous front surface and a plurality of actuators to its back surface. The back surface is divided into triangular areas which are mutually separated by grooves. The grooves are deep enough to make the plate deformable and the actuators for displacing the mirror plate in the direction normal to its surface are inserted in the grooves at the vertices of the triangular areas. Each actuator includes a transducer supported by a receptacle with outer shells having outer surfaces. The vertices have inner walls which are approximately perpendicular to the mirror surface and make planar contacts with the outer surfaces of the outer shells. The adhesive which is used on these contact surfaces tends to contract when it dries but the outer shells can bend and serve to minimize the tendency of the mirror to warp.

  1. Evaluation of root canal morphology of human primary molars by using CBCT and comprehensive review of the literature.

    PubMed

    Ozcan, Gozde; Sekerci, Ahmet Ercan; Cantekin, Kenan; Aydinbelge, Mustafa; Dogan, Salih

    2016-05-01

    Objective Knowledge of primary tooth morphology is essential for clinical dentistry, especially for root canal treatment and dental traumatology. However, this has not been well documented to date with a large sample. This study was carried out to investigate the variation in number and morphology of the root canals of the primary molars, to study the applicability of cone beam computerized tomography (CBCT) in assessing the same and to provide a comprehensive review of the literature. Materials and methods A total of 343 primary molars, without any root resorption, were divided into four main groups including the maxillary first molars, maxillary second molars, mandibular first molars and mandibular second molars. All of them were analysed in CBCT images in the axial, sagittal and coronal planes. Various parameters such as the number of roots, number of canals, the root canal type, diameter of root and root canal and root canal curvature were studied. Results Primary molars in all four groups showed variability in the number of roots and root canals. As far as length of the roots was concerned, the palatal root of the maxillary molar was found to be longest, while the distobuccal root was shortest. In mandibular molars, the mesial root was longer than the distal root. The length of distobuccal root canal of the maxillary molars and the distolingual canal of the mandibular molars was found to be shortest. The number of roots and root canals varied from two to four and three to four, respectively. The maxillary molars exhibited more one-canal than two-canal roots. Conclusion The present study provides comprehensive information to the existing literature concerning the variation in root canal morphology of the maxillary and mandibular primary molar teeth. These data may help clinicians in the root canal treatment of these teeth. PMID:26523502

  2. Kissing molars: report of three cases and new prospective on aetiopathogenetic theories

    PubMed Central

    Menditti, Dardo; Laino, Luigi; Cicciù, Marco; Mezzogiorno, Antonio; Perillo, Letizia; Menditti, Marco; Cervino, Gabriele; Muzio, Lorenzo Lo; Baldi, Alfonso

    2015-01-01

    Kissing molars (KMs) is an extremely rare condition of impacted third molars, pointed in the opposite direction in a single follicular space; it consists exactly in a full impacted of permanent molars which occurs only in the lower jaw. Actually, about less than thirty cases have been reported in scientific literatures. The aetiology and pathogenesis of this pathological double dental inclusion remain unknown; above all events that lead two molars to appear, as KMs remain mysterious. The association to metabolic connective diseases such as mucopolysaccharidosis was emphasized. KMs considered as an isolated event, may be associated to an abnormal position of the tooth-bud from lower permanent molars, or fourth supernumerary tooth (distomolar). Recently, hyperplastic dental follicle (HDF), with a down regulation of matrix metal-proteinases and up regulation of several genes of collagens, has been mentioned in association with KMs. In this paper, after having analyzed three new cases of KMs that have been treated, we report a new hypothesis. This last is based on the failure in the dental follicle’s ability to initiate or continue properly resorption of the overlying alveolar bone, by many exogenous factors which may act on eruptive phase that would lead to its rotation with its contents coming out a pathological situation of KMs. The therapy of choice is related to the surgical removal of KMs through a double odontectomy with transalveolar method. Other treatments can be, eventually, orthodontic therapy of the impacted teeth and a radiological follow-up without surgery. PMID:26884840

  3. Structural Morphology of Molars in Large Mammalian Herbivores: Enamel Content Varies between Tooth Positions

    PubMed Central

    Winkler, Daniela E.; Kaiser, Thomas M.

    2015-01-01

    The distribution of dental tissues in mammalian herbivores can be very different from taxon to taxon. While grazers tend to have more elaborated and complexly folded enamel ridges, browsers have less complex enamel ridges which can even be so far reduced that they are completely lost. The gradient in relative enamel content and complexity of structures has so far not been addressed within a single species. However, several studies have noted tooth position specific wear rates in small mammals (rabbits, guinea pigs) which may be related to individual tooth morphology. We investigate whether differentiated enamel content by tooth position is also to be found in large herbivores. We use CT-scanning techniques to quantify relative enamel content in upper and lower molar teeth of 21 large herbivorous mammal species. By using a broad approach and including both perissodactyls and artiodactyls, we address phylogenetic intraspecific differences in relative enamel content. We find that enamel is highly unevenly distributed among molars (upper M1, M2, M3 and lower m1, m2, m3) in most taxa and that relative enamel content is independent of phylogeny. Overall, relative enamel content increases along the molar tooth row and is significantly higher in lower molars compared to upper molars. We relate this differential enamel content to prolonged mineralisation in the posterior tooth positions and suggest a compensatory function of m3 and M3 for functional losses of anterior teeth. PMID:26313359

  4. In vitro evaluation of an alternative method to bond molar tubes

    PubMed Central

    PINZAN-VERCELINO, Célia Regina Maio; PINZAN, Arnaldo; GURGEL, Júlio de Araújo; BRAMANTE, Fausto Silva; PINZAN, Luciana Maio

    2011-01-01

    Despite the advances in bonding materials, many clinicians today still prefer to place bands on molar teeth. Molar bonding procedures need improvement to be widely accepted clinically. Objective The purpose of this study was to evaluate the shear bond strength when an additional adhesive layer was applied on the occlusal tooth/tube interface to provide reinforcement to molar tubes. Material and methods Sixty third molars were selected and allocated to the 3 groups: group 1 received a conventional direct bond followed by the application of an additional layer of adhesive on the occlusal tooth/tube interface, group 2 received a conventional direct bond, and group 3 received a conventional direct bond and an additional cure time of 10 s. The specimens were debonded in a universal testing machine. The results were analyzed statistically by ANOVA and Tukey’s test (α=0.05). Results Group 1 had a significantly higher (p<0.05) shear bond strength compared to groups 2 and 3. No difference was detected between groups 2 and 3 (p>0.05). Conclusions The present in vitro findings indicate that the application of an additional layer of adhesive on the tooth/tube interface increased the shear bond strength of the bonded molar tubes. PMID:21437468

  5. Ectopic third molar in the mandibular condyle: A review of the literature

    PubMed Central

    Iglesias-Martin, Fernando; Torres-Carranza, Eusebio; Prats-Golczer, Victoria-Eugenia; Garcia-Perla-Garcia, Alberto

    2012-01-01

    Objectives: To evaluate the etiopathogenesis, clinical features, therapeutic options, and surgical approaches for removal of ectopic third molars in the mandibular condyle. Study design: MEDLINE search of articles published on ectopic third molars in the mandibular condyle from 1980 to 2011. 14 well-documented clinical cases from the literature were evaluated together with a new clinical case provided by the authors, representing a sample of 15 patients. Results: We found a mean age at diagnosis of 48.6 years and a higher prevalence in women. In 14 patients, associated radiolucent lesions were diagnosed on radiographic studies and confirmed histopathologically as odontogenic cysts. Clinical symptoms were pain and swelling in the jaw or preauricular region, trismus, difficulty chewing, cutaneous fistula and temporomandibular joint dysfunction. Treatment included conservative management in one case and in the other cases, surgical removal by intra- or extraoral approaches, the latter being the most common approach carried out. In most reported cases, serious complications were not outlined. Conclusions: The etiopathogenic theory involving odontogenic cysts in the displacement of third molars to the mandibular condyle seems to be the most relevant. They must be removed if they cause symptoms or are associated with cystic pathology. The surgical route must be planned according to the location and position of the ectopic third molar, and the possible morbidity associated with surgery. Key words:Third molar, ectopic tooth, condyle, mandible. PMID:22926463

  6. Patient anxiety and surgical difficulty in impacted lower third molar extractions: a prospective cohort study.

    PubMed

    Aznar-Arasa, L; Figueiredo, R; Valmaseda-Castelln, E; Gay-Escoda, C

    2014-09-01

    Encountering patients who are fearful and anxious is common in dental practice and these factors can increase the complexity of dental procedures. A prospective cohort study was performed to assess whether patient anxiety influences the difficulty of impacted lower third molar extraction and to identify other predictive factors of surgical difficulty; 102 extractions done under local anaesthesia were assessed. Several preoperative variables were recorded (demographic, anatomical, and surgical) and patient anxiety was assessed through the use of various questionnaires. Extraction difficulty was measured using the operation time (OT) and a 100-mm visual analogue scale (difficulty VAS) completed by the surgeon. Patients with deep impacted third molars that required bone removal and tooth sectioning showed higher levels of preoperative anxiety. Significant correlations were found between questionnaire scores and the surgical difficulty (OT and difficulty VAS). OT was also related to age, depth of impaction, third molar angulations, proximity of the third molar roots to the mandibular canal, hard and soft tissue coverage, and the need to perform an ostectomy and tooth sectioning. Impacted lower third molar extraction is significantly more difficult in anxious patients. Other demographic, radiological, and surgical factors were also found to be significantly related to the surgical difficulty. PMID:24837553

  7. Containing the cost of third-molar extractions: a dilemma for health insurance.

    PubMed Central

    Friedman, J W

    1983-01-01

    No known scientific studies support the extraction of third molars (wisdom teeth) to prevent future disease. Yet, third-molar surgery for this purpose has become so common that in at least one major U.S. health insurance plan, the cumulative cost exceeds that for every other kind of major surgery. Many third molars that are developing normally in adolescents are classified as impacted and removed before they erupt, a practice that results in large expenditures for unnecessary surgery. In addition, the difficulty of the extractions is frequently exaggerated, so that patients and insurance plans are overcharged. Third molar surgery is not without risk of iatrogenic injury. Fracture of the jaw, permanent numbness of the lip (paresthesia), and injury to other teeth may occur. This paper presents a mechanism for containing the cost of third-molar surgery by elimination of payment for nonessential extractions and of the related overcharges. Adoption of this policy by administrators of dental insurance plans would save millions of dollars each year, money that could be better used in providing care for more people with real dental disease. PMID:6611824

  8. Studies of the chronological course of third molars eruption in a northern Chinese population.

    PubMed

    Guo, Yu-cheng; Yan, Chun-xia; Lin, Xing-wei; Zhou, Hong; Pan, Feng; Wei, Lai; Tang, Zheng; Liang, Feng; Chen, Teng

    2014-09-01

    Dental age estimation is of great importance for individual identification in forensic medicine and many other fields of study. Among them, tooth eruption is a parameter developmental morphology that can be determined by clinical examinations or by dental X-rays. The purpose of present research is to study the chronological course of third molars eruption in a Chinese population and compare that with other ethnic population for age estimation. A total of 1135 conventional orthopantomograms from 506 male and 629 female northern Chinese subjects aged between 11 and 26 years were analyzed. The eruption status of the third molars was assessed using the developmental stages described by Olze et al. Results showed that the third molars 18, 28, 38 and 48 in the stage A showed significant younger average age in males than in females. The Olze's stage A could be used as a reference stage to determine whether a male or female northern Chinese is likely to be equal or above age 16, with 99.6-100% and 97.4-98.1% of correct predictions, respectively. The stage D was found to be a useful marker for diagnosing age under 16 years, with 98.9-100% and 100% of correct predictions in males and females, respectively. There were some significant differences of the chronological course of the third molars eruption in different ethnic groups, which indicated that population-specific standards could enhance the accuracy of forensic age estimation based on third molar eruption. PMID:24907520

  9. Gender Determination Using Diagonal Measurements of Maxillary Molar and Canine Teeth in Davangere Population

    PubMed Central

    Tarigoppula, Ratna Kumari V. N.; Kulkarni, Pavan G; BS, Anil

    2014-01-01

    Background: Mesiodistal and buccolingual measurements of the teeth have been the traditional means of determining gender which sometimes are difficult to measure. Aims and Objectives: To assess the degree of sexual dimorphism in upper permanent canines and first molars using diagonal diameters and to evaluate the applicability of diagonal measurements in sex determination. Materials and Methods: Mesiobuccal-distolingual (MBDL) and distobuccal-mesiolingual (DBML) measurements of the crown and cervix of maxillary canine and maxillary molar were taken using digital vernier callipers in 100 upper dental casts obtained from 50 males and 50 females of the age group of 17-25 y. Results: With step wise discriminant function analysis, results were statistically significant with males showing higher diagonal measurement values. The classification accuracy for males was 69% and in females was 73% with overall accuracy of 71%. Results showed that canines exhibited highest accuracy with cervical measurements being more dimorphic. MBDL measurements were found to be more reliable. Most dimorphicmeasurements included right molar cervical MBDL, left molar cervical MBDL followed by right and left molar crown MBDL. Conclusion: In cases of tooth rotations, crowding, certain fillings and attritions where traditional mesio-distal and bucco-lingual measurements are not applicable, diagonal measurements could be of help in predicting gender. PMID:25584308

  10. Structural Morphology of Molars in Large Mammalian Herbivores: Enamel Content Varies between Tooth Positions.

    PubMed

    Winkler, Daniela E; Kaiser, Thomas M

    2015-01-01

    The distribution of dental tissues in mammalian herbivores can be very different from taxon to taxon. While grazers tend to have more elaborated and complexly folded enamel ridges, browsers have less complex enamel ridges which can even be so far reduced that they are completely lost. The gradient in relative enamel content and complexity of structures has so far not been addressed within a single species. However, several studies have noted tooth position specific wear rates in small mammals (rabbits, guinea pigs) which may be related to individual tooth morphology. We investigate whether differentiated enamel content by tooth position is also to be found in large herbivores. We use CT-scanning techniques to quantify relative enamel content in upper and lower molar teeth of 21 large herbivorous mammal species. By using a broad approach and including both perissodactyls and artiodactyls, we address phylogenetic intraspecific differences in relative enamel content. We find that enamel is highly unevenly distributed among molars (upper M1, M2, M3 and lower m1, m2, m3) in most taxa and that relative enamel content is independent of phylogeny. Overall, relative enamel content increases along the molar tooth row and is significantly higher in lower molars compared to upper molars. We relate this differential enamel content to prolonged mineralisation in the posterior tooth positions and suggest a compensatory function of m3 and M3 for functional losses of anterior teeth. PMID:26313359

  11. The incidence of cysts and tumors associated with impacted third molars

    PubMed Central

    Vigneswaran, A. T.; Shilpa, S.

    2015-01-01

    Incidence of cysts and tumors associated with lower impacted third molars are very low prevalence, which might be because of the fact that most pathologies go unnoticed as many practitioners discard the erupted tissue after surgical removal of the impacted teeth rather than sending the tissue for histopathological examination. Our aim was to evaluate the patients who came for third molar surgical removal with due therapeutic prophylacis and an incidental finding. A proper study protocol both inclusion and exclusion criteria was strictly followed for all the cases, which were included in the study. The period of study was 6 years and the total number of cases assessed were 2778 patients out of which 70 cases reported pathology associated with the impacted third molars. Among 70 cases 61.4% were reported as cyst and tumors and 38.6% of the cases had chronic inflammatory reaction, including two cases with normal dental follicle. High incidence rate of pathology associated with third molar occurred between age group of 20 and 30 years older age groups showed very low incidence. Most common site of impaction was found to be left side of mandible and positions were vertical and distoangular impactions. Thus was male predominance in the younger groups. The examination is necessary whether the third molars impacted cases were symptomatic or asymptomatic PMID:26015725

  12. Shear bond strength of partial coverage restorations to dentin

    PubMed Central

    Agustn-Panadero, Rubn; Alonso-Prez-Barquero, Jorge; Fons-Font, Antonio; Sol-Ruz, Mara-Fernanda

    2015-01-01

    Background When partial coverage restorations (veneers, inlays, onlays) must be cemented to dentin, bond strength may not reach the same predictable values as to enamel. The purpose of this study was: 1. To compare, with a shear bond test, the bond strength to dentin of a total-etch and a self-etching bonding agent. 2. To determine whether creating microretention improves the bond strength to dentin. Material and Methods Two bonding agents were assayed, Optibond FL (Kerr), two-bottle adhesive requiring acid etching, and Clearfil SE Bond (Kuraray), two-bottle self-etching adhesive. The vestibular, lingual, distal and mesial surfaces of ten molars (n=10) were ground to remove all enamel and 40 ceramic samples were cemented with Variolink II (Ivoclar Vivadent). Half the molar surfaces were treated to create round microretention (pits) to determine whether these could influence bond strength to dentin. The 40 molar surfaces were divided into four groups (n=10): Optibond FL (O); Clearfil SE (C); Optibond FL + microretention (OM); Clearfil SE + micro retention (CM). A shear bond test was performed and the bond failures provoked examined under an optical microscope. Results O=35.278.02 MPa; C=36.2311.23 MPa; OM=28.616.27 MPa; CM=27.017.57 MPa. No statistically significant differences were found between the adhesives. Optibond FL showed less statistical dispersion than Clearfil SE. The presence of microretentions reduced bond strength values regardless of the adhesive used. Conclusions 1. Clearfil SE self-etching adhesive and Optibond FL acid-etch showed adequate bond strengths and can be recommended for bonding ceramic restorations to dentin. 2. The creation of round microretention pits compromises these adhesives bond strength to dentin. Key words:Adhesion to dentin, bonding agent, Optibond FL, Clearfil SE, microretention, shear bond test. PMID:26330937

  13. Continuously growing rodent molars result from a predictable quantitative evolutionary change over 50 million years.

    PubMed

    Tapaltsyan, Vagan; Eronen, Jussi T; Lawing, A Michelle; Sharir, Amnon; Janis, Christine; Jernvall, Jukka; Klein, Ophir D

    2015-05-01

    The fossil record is widely informative about evolution, but fossils are not systematically used to study the evolution of stem-cell-driven renewal. Here, we examined evolution of the continuous growth (hypselodonty) of rodent molar teeth, which is fuelled by the presence of dental stem cells. We studied occurrences of 3,500 North American rodent fossils, ranging from 50 million years ago (mya) to 2 mya. We examined changes in molar height to determine whether evolution of hypselodonty shows distinct patterns in the fossil record, and we found that hypselodont taxa emerged through intermediate forms of increasing crown height. Next, we designed a Markov simulation model, which replicated molar height increases throughout the Cenozoic and, moreover, evolution of hypselodonty. Thus, by extension, the retention of the adult stem cell niche appears to be a predictable quantitative rather than a stochastic qualitative process. Our analyses predict that hypselodonty will eventually become the dominant phenotype. PMID:25921530

  14. Maxillary first molar with an O-shaped root morphology: report of a case

    PubMed Central

    Shin, Yooseok; Kim, Yemi; Roh, Byoung-Duck

    2013-01-01

    This case report is to present a maxillary first molar with one O-shaped root, which is an extended C-shaped canal system. Patient with chronic apical periodontitis in maxillary left first molar underwent replantation because of difficulty in negotiating all canals. Periapical radiographs and cone-beam computed tomography (CBCT) were taken. All roots were connected and fused to one root, and all canals seemed to be connected to form an O-shape. The apical 3mm of the root were resected and retrograde filled with resin-modified glass ionomer. Intentional replantation as an alternative treatment could be considered in a maxillary first molar having an unusual O-shaped root. PMID:24008268

  15. Preformed metal crowns for primary and permanent molar teeth: review of the literature.

    PubMed

    Randall, Ros C

    2002-01-01

    The aim of this study was to carry out a review of the use and efficiency of preformed metal crowns (PMCs) for primary and permanent molar teeth. A literature search of English language journals was carried out using MEDLINE. Papers that addressed areas related to the use of PMCs regarding indications for use, placement techniques, risks, longevity, cost effectiveness and utilization were included in the review. Eighty-three papers were traced which fulfilled the above criteria, the majority addressing PMCs in primary molar teeth. Over half the papers were concerned with placement techniques and indications for use, with fewer papers reporting on clinical studies. The clinical data on PMCs spanned a considerable number of years and involved heterogeneous populations of patients, different makes and designs of crown, and differences among the operators and evaluators who were involved in the studies. The results, however, were in agreement that PMCs are superior to amalgam restorations for multisurface cavities in primary molar teeth. PMID:12412964

  16. An Evaluation of Pathologic Changes in the Follicle of Impacted Mandibular Third Molars

    PubMed Central

    Tambuwala, Aruna Azhar; Oswal, Rakesh Gulabchand; Desale, Rushikesh Suresh; Oswal, Nitin Prakash; Mall, Prashant Edwin; Sayed, Aatif Riyaz; Pujari, Aniket Tarachand

    2015-01-01

    Background: The purpose of this study was to evaluate the early pathologic changes in the follicular tissue of completely impacted mandibular third molar. Materials and Methods: 52 patients, between 18 and 52 years of age of which 25 were males and 27 were females, were selected. They had impacted mandibular third molars, which were indicated for extraction. After extraction, the follicle was sent for a histopathological evaluation to two different oral pathologists. Results: The results showed that 80.8% of the specimen had normal follicles. 11.5% specimen suggested cystic changes while 7.7% suggested infected follicle. Conclusion: It is desirable to consider prophylactic removal of impacted mandibular third molar presenting at a younger age, whereas their removal remains an enigma for the older age group and should only be considered appropriate in those cases where frank causes for its removal are established. PMID:25954073

  17. Accessory Central Cusp in the Maxillary Second Primary Molars: A Rare Entity among the Rare

    PubMed Central

    Das, Monalisa

    2014-01-01

    ABSTRACT% Central accessory cusp in primary molars is an extremely rare condition which is due to abnormal proliferation and folding of inner enamel epithelium during morphodifferentiation stage of tooth development. The extension of the pulp in the cuspal area is often the reason for early involvement of pulp by the caries process. Therefore, early diagnosis and treatment planning is necessary to maintain the integrity of primary dental arch. This article reports such a case of central accessory cusps involving maxillary second primary molars. How to cite this article: Chandra B, Das M. Accessory Central Cusp in the Maxillary Second Primary Molars: A Rare Entity among the Rare. Int J Clin Pediatr Dent 2014;7(3):202-205. PMID:25709302

  18. Lingual nerve injury after third molar removal: Unilateral atrophy of fungiform papillae

    PubMed Central

    de-Pablo-Garcia-Cuenca, Alba; Bescs-Atn, Maria S.

    2014-01-01

    Background: Pain and sensory changes due to lingual nerve injury are one of the most common alterations that follow surgical removal of third molar. They are usually transient but other less common complications, such as the atrophy of fungiform papillae, have an uncertain prognosis. Case Description: We report a case of a 34-year-old woman who presented a unilateral lingual atrophy of fungiform papillae after third molar extraction accompanied by severe dysesthesia that altered her daily life significantly during the following months and how this complication evolved over time. We conducted a literature review on the different factors that can lead to a lingual nerve injury. Clinical Implications: The clinical evolution of temporary and permanent somatosensitve injuries is an important fact to take into consideration during the postoperative management because it will indicate the lesion prognosis. Key words:Lingual nerve, third molar removal, somatosensitive alteration, papillae atrophy, permanent injury, temporary injury. PMID:24790723

  19. An evaluation of intraoral molar distalization with nickel-titanium coil springs.

    PubMed

    Oztrk, Yildiz; Firatli, Sonmez; Alma, Levent

    2005-10-01

    The purpose of this study was to determine dental and skeletal effects of compressed nickel-titanium coil springs used for distal movement of the maxillary molars. Initial and follow-up cephalometric radiographs were taken of 8 patients (2 males and 6 females) in the late mixed or permanent dentition stage with Class II malocclusion. Nickel-titanium coil springs exerting a near constant force of approximately 250 g were compressed against the maxillary molar tubes by Gurin locks. The mean treatment time was 6.95 +/- 0.2 months. Dental and skeletal changes were determined as follows: The mean maxillary first molar distalization was 5.44 mm (right) and 3.75 mm (left), with a mesial tipping of 11.56 degrees (right) and 11.34 degrees (left). Anchorage loss occurred as defined by mesial movement of the first premolars and proclination of the central incisors. Vertical dental and skeletal dimensions were not affected. PMID:16163876

  20. Analysis of masseter and temporal muscles during surgical extraction of impacted third molars.

    PubMed

    Moraes, Michelle B; Naclerio-Homem, Maria G; Nascimento, Rodrigo D; Oliveira Amorim, Jose Benedito; Raldi, Fernando V

    2015-01-01

    With the aim of contributing to the discussion on stomatognathic system dysfunction after surgical procedures, this study compared the electromyographic activity of the superficial masseter and temporal masticatory muscles before, during, and after impacted mandibular third molar extractions. Muscular activity was recorded presurgery, transsurgery, immediately postoperatively, and on postoperative days 7, 15, and 30. Twenty patients requiring extraction of impacted mandibular third molars were selected and evaluated. In 20 patients who underwent mandibular third molar extractions, electromyography showed no alterations in muscle tone, and no statistically significant differences were observed in the left and right temporal and masseter muscles at any of the experimental periods at either mandibular rest or isometric contraction position. However, the degree of mouth opening increased 11.76% from pretreatment to 30 days after surgery. These results may reflect the shorter, careful extraction procedure performed by the surgeon. PMID:26325653

  1. Radix Entomolaris in Mandibular First Molars in Indian Population: A Review and Case Reports

    PubMed Central

    Attam, Kanika; Nawal, Ruchika Roongta; Utneja, Shivani; Talwar, Sangeeta

    2012-01-01

    Purpose. The aim of this paper is to present cases of mandibular first molars with an additional distolingual root and their management using appropriate instruments and techniques. Basic Procedures and Main Findings. Mandibular molars can sometimes present a variation called radix entomolaris, wherein the tooth has an extra root attached to its lingual aspect. This additional root may complicate the endodontic management of the tooth if it is misdiagnosed or maltreated. This paper reviews the prevalence of such cases in Indian population and reports the management of 6 such teeth. Principal Conclusions. (1) It is crucial to be familiar with variations in tooth/canal anatomy and characteristic features since such knowledge can aid location and negotiation of canals, as well as their subsequent management. (2) Accurate diagnosis and careful application of clinical endodontic skill can favorably alter the prognosis of mandibular molars with this root morphology. PMID:23125938

  2. Asymmetry in mesial root number and morphology in mandibular second molars: a case report

    PubMed Central

    Shetty, Shashit; Shekhar, Rhitu

    2014-01-01

    Ambiguity in the root morphology of the mandibular second molars is quite common. The most common root canal configuration is 2 roots and 3 canals, nonetheless other possibilities may still exist. The presence of accessory roots is an interesting example of anatomic root variation. While the presence of radix entomolaris or radix paramolaris is regarded as a typical clinical finding of a three-rooted mandibular second permanent molar, the occurrence of an additional mesial root is rather uncommon and represents a possibility of deviation from the regular norms. This case report describes successful endodontic management of a three-rooted mandibular second molar presenting with an unusual accessory mesial root, which was identified with the aid of multiangled radiographs and cone-beam computed tomography imaging. This article also discusses the prevalence, etiology, morphological variations, clinical approach to diagnosis, and significance of supernumerary roots in contemporary clinical dentistry. PMID:24516829

  3. Holocellulose Nanofibers of High Molar Mass and Small Diameter for High-Strength Nanopaper.

    PubMed

    Galland, Sylvain; Berthold, Fredrik; Prakobna, Kasinee; Berglund, Lars A

    2015-08-10

    Wood cellulose nanofibers (CNFs) based on bleached pulp are different from the cellulose microfibrils in the plant cell wall in terms of larger diameter, lower cellulose molar mass, and modified cellulose topochemistry. Also, CNF isolation often requires high-energy mechanical disintegration. Here, a new type of CNFs is reported based on a mild peracetic acid delignification process for spruce and aspen fibers, followed by low-energy mechanical disintegration. Resulting CNFs are characterized with respect to geometry (AFM, TEM), molar mass (SEC), and polysaccharide composition. Cellulose nanopaper films are prepared by filtration and characterized by UV-vis spectrometry for optical transparency and uniaxial tensile tests. These CNFs are unique in terms of high molar mass and cellulose-hemicellulose core-shell structure. Furthermore, the corresponding nanopaper structures exhibit exceptionally high optical transparency and the highest mechanical properties reported for comparable CNF nanopaper structures. PMID:26151837

  4. Peri-operative concerns in a patient with thyroid storm secondary to molar pregnancy

    PubMed Central

    Samra, Tanvir; Kaur, Ranvinder; Sharma, Neha; Chaudhary, Lalita

    2015-01-01

    Awareness of the presence of thyroid function abnormalities in patients with molar pregnancy is important for its prompt diagnosis and management. We report the development of thyroid storm in the immediate post-operative period in a 25-year-old female who underwent evacuation of her molar pregnancy under saddle spinal block after being controlled for her thyrotoxicosis with a combination of antithyroid drugs, iodine, steroids and adrenergic blocking agents. We advocate the use of esmolol infusions up to a maximum dose of 200 ?g/kg/min for immediate haemodynamic management of the patient. Optimum time needed for stabilisation of the hyper metabolic state after initiation of antithyroid drugs is still not known and evacuation of molar pregnancy remains the only definitive management of the thyrotoxic state. PMID:26755840

  5. Peri-operative concerns in a patient with thyroid storm secondary to molar pregnancy.

    PubMed

    Samra, Tanvir; Kaur, Ranvinder; Sharma, Neha; Chaudhary, Lalita

    2015-11-01

    Awareness of the presence of thyroid function abnormalities in patients with molar pregnancy is important for its prompt diagnosis and management. We report the development of thyroid storm in the immediate post-operative period in a 25-year-old female who underwent evacuation of her molar pregnancy under saddle spinal block after being controlled for her thyrotoxicosis with a combination of antithyroid drugs, iodine, steroids and adrenergic blocking agents. We advocate the use of esmolol infusions up to a maximum dose of 200 ?g/kg/min for immediate haemodynamic management of the patient. Optimum time needed for stabilisation of the hyper metabolic state after initiation of antithyroid drugs is still not known and evacuation of molar pregnancy remains the only definitive management of the thyrotoxic state. PMID:26755840

  6. Autotransplantation of Immature Third Molars and Orthodontic Treatment After En Bloc Resection of Conventional Ameloblastoma.

    PubMed

    Osterne, Rafael Lima Verde; Moreira Neto, Jos Jeov Siebra; de Arajo Lima, Augusto Darwin Moreira; Nogueira, Renato Luiz Maia

    2015-09-01

    Ameloblastoma treatment can lead to significant bone defects; consequently, oral rehabilitation can be challenging. We present the case of a 14-year-old girl diagnosed with a conventional ameloblastoma in the mandible who was treated using en bloc resection and rehabilitated with autotransplantation of the immature third molars and orthodontic treatment. The lesion was in the region of the lower left canine and premolars, and en bloc resection resulted in a significant alveolar bone defect. Autotransplantation of the lower third molars to the site of the lower left premolars was performed. After 2 years, the upper left third molar was transplanted to the site of the lower left canine. During the orthodontic treatment period, considerable alveolar bone formation was observed in the region of the transplanted teeth, and roots developed. To the best of our knowledge, this is the first reported case of alveolar bone formation induction caused by tooth transplantation after ameloblastoma treatment. PMID:26044604

  7. Formation of polyelectrolyte complexes with diethylaminoethyl dextran: charge ratio and molar mass effect.

    PubMed

    Le Cerf, Didier; Pepin, Anne Sophie; Niang, Pape Momar; Cristea, Mariana; Karakasyan-Dia, Carole; Picton, Luc

    2014-11-26

    The formation of polyelectrolyte complexes (PECs) between carboxymethyl pullulan and DEAE Dextran, was investigated, in dilute solution, with emphasis on the effect of charge density (molar ratio or pH) and molar masses. Electrophoretic mobility measurements have evidenced that insoluble PECs (neutral electrophoretic mobility) occurs for charge ratio between 0.6 (excess of polycation) and 1 (stoichiometry usual value) according to the pH. This atypical result is explained by the inaccessibility of some permanent cationic charge when screened by pH dependant cationic ones (due to the Hoffman alkylation). Isothermal titration calorimetry (ITC) indicates an endothermic formation of PEC with a binding constant around 10(5) L mol(-1). Finally asymmetrical flow field flow fractionation coupled on line with static multi angle light scattering (AF4/MALS) evidences soluble PECs with very large average molar masses and size around 100 nm, in agreement with scrambled eggs multi-association between various polyelectrolyte chains. PMID:25256478

  8. Aperiodic Volume Optics

    NASA Astrophysics Data System (ADS)

    Gerke, Tim D.

    Presented in this thesis is an investigation into aperiodic volume optical devices. The three main topics of research and discussion are the aperiodic volume optical devices that we call computer-generated volume holograms (CGVH), defects within periodic 3D photonic crystals, and non-periodic, but ordered 3D quasicrystals. The first of these devices, CGVHs, are designed and investigated numerically and experimentally. We study the performance of multi-layered amplitude computer-generated volume holograms in terms of efficiency and angular/frequency selectivity. Simulation results show that such aperiodic devices can increase diffraction efficiency relative to periodic amplitude volume holograms while maintaining angular and wavelength selectivity. CGVHs are also designed as voxelated volumes using a new projection optimization algorithm. They are investigated using a volumetric diffraction simulation and a standard 3D beam propagation technique as well as experimentally. Both simulation and experiment verify that the structures function according to their design. These represent the first diffractive structures that have the capacity for generating arbitrary transmission and reflection wave fronts and that provide the ability for multiplexing arbitrary functionality given different illumination conditions. Also investigated and discussed in this thesis are 3D photonic crystals and quasicrystals. We demonstrate that these devices can be fabricated using a femtosecond laser direct writing system that is particularly appropriate for fabrication of such arbitrary 3D structures. We also show that these devices can provide 3D partial bandgaps which could become complete bandgaps if fabricated using high index materials or by coating lower index materials with high index metals. Our fabrication method is particularly suited to the fabrication of engineered defects within the periodic or quasi-periodic systems. We demonstrate the potential for fabricating defects within periodic and quasi-periodic systems for the manipulation of light in the IR regime. The general thesis of this document is that aperiodic three-dimensional structures provide additional degrees of freedom that can be utilized to improve on the performance of periodic volume devices. The results we will discuss suggest that, under certain circumstances, a departure from the Bragg paradigm provides enhanced volume diffraction properties.

  9. [Realization of algorithm on finishing optimization-tool-path generation for high-speed machining molar crown].

    PubMed

    Sun, Quanping; Chen, Xiaogang; Chen, Qianliang; Dai, Ning; Liao, Wenhe; He, Ning

    2009-10-01

    Molar crown is very small and has not only thin-wall, but also complex profile, especially, the occlusal surface of each molar crown has many cusps, ridges and fossae being differently distributed. When conventional processing method is used, it is impossible to machine molar prosthesis rapidly and exactly. To enhance machining velocity and improve the surface precision of molar crown, an algorithm of entity rapid offset-based STL format is put forward. By the application of Zigzag toolpath planning and micro-machining cutter, the finishing toolpaths for high speed milling molar prosthesis are generated. In terms of Mikron UCP800 high-speed machine center, the molar all-crown made of alloy aluminum material is successfully machined. The test results show that the algorithm of tool-path generation works fast, the number of toolpaths is small, and the cutter feeds smoothly. PMID:19947500

  10. Efficacy of the technique of piezoelectric corticotomy for orthodontic traction of impacted mandibular third molars.

    PubMed

    Ma, Zhigui; Xu, Guangzhou; Yang, Chi; Xie, Qianyang; Shen, Yuqing; Zhang, Shanyong

    2015-04-01

    Our aim was to assess the efficacy of piezoelectric corticotomy for orthodontic traction of mandibular third molars close to the inferior alveolar nerve. Thirty patients with impacted third molars close to the nerve were included in the study, 15 of whom were treated with conventional orthodontic traction and 15 with piezoelectric corticotomy. We recorded duration of treatment including exposure and orthodontic traction, and time to the final extraction. Postoperative complications including trismus, swelling, and pain were also noted. Alveolar bone levels mesial and distal to the second molars were evaluated on cone-beam computed tomographic (CT) images. Student's t test was used to assess the significance of differences between the groups. After orthodontic treatments all impacted third molars were successfully removed from the inferior alveolar nerve without neurological damage. The mean (SD) duration of surgical exposure in the piezoelectric corticotomy group was significantly longer than that in the conventional group (p=0.01). The mean (SD) duration of traction was 4 (2.3) months after piezoelectric corticotomy, much shorter than the 7.5 (1.3) months in the conventional group (p=0.03). There were no significant differences in postoperative complications between the groups. There was a significant increase in the distal alveolar height of second molars after treatment in both groups (p<0.01). We conclude that the use of piezoelectric corticotomy allows more efficient and faster traction of third molars with a close relation between the root and the inferior alveolar nerve, although it took longer than the traditional technique. PMID:25638568

  11. Classification of impacted mandibular third molars on cone-beam CT images

    PubMed Central

    Maglione, Michele; Bazzocchi, Gabriele

    2015-01-01

    Background Neurological involvement is a serious complication associated to the surgical removal of impacted mandibular third molars and the radiological investigation is the first mandatory step to assess the risk of a possible post-operative injury to the inferior alveolar nerve (IAN). The aim of this study was to introduce a new radiological classification that could be normally used in clinical practice to assess the relationship between an impacted third molar and mandibular canal on cone beam CT (CBCT) images. Material and Methods CBCT images of 80 patients (133 mandibular third molars) were independently studied by three members of the surgical team to draw a classification that could describe all the possible relationships between third molar and IAN on the cross-sectional images. Subsequently, the study population was subdivided according to this classification. The SPSS software, version 15.0 (SPSS Inc., Chicago, Illinois, USA) was used for the statistical analysis. Results Eight different classes were proposed (classes 0-7) and six of them (classes 1-6) were subdivided in two subtypes (subtypes A-B). The distribution of classes showed a prevalence of buccal or apical course of the mandibular canal followed by lingual position and inter-radicular one. No differences have resulted in terms of anatomic relationship between males and females apart from a higher risk of real contact without corticalization of the canal when the IAN had a lingual course for female group. Younger patients showed an increased rate of direct contact with a reduced calibre of the canal and/or without corticalization. Conclusions The use of this classification could be a valid support in clinical practice to obtain a common language among operators in order to define the possible relationships between an impacted third molar and the mandibular canal on CBCT images. Key words:CBCT, classification, inferior alveolar nerve, third molars. PMID:26155337

  12. Ultrastructure of the surface of dental enamel with molar incisor hypomineralization (MIH) with and without acid etching.

    PubMed

    Bozal, Carola B; Kaplan, Andrea; Ortolani, Andrea; Cortese, Silvina G; Biondi, Ana M

    2015-08-01

    The aim of the present work was to analyze the ultrastructure and mineral composition of the surface of the enamel on a molar with MIH, with and without acid etching. A permanent tooth without clinical MIH lesions (control) and a tooth with clinical diagnosis of mild and moderate MIH, with indication for extraction, were processed with and without acid etching (H3PO4 37%, 20") for observation with scanning electron microscope (SEM) ZEISS (Supra 40) and mineral composition analysis with an EDS detector (Oxford Instruments). The control enamel showed normal prismatic surface and etching pattern. The clinically healthy enamel on the tooth with MIH revealed partial loss of prismatic pattern. The mild lesion was porous with occasional cracks. The moderate lesion was more porous, with larger cracks and many scales. The mineral composition of the affected surfaces had lower Ca and P content and higher O and C. On the tooth with MIH, even on normal looking enamel, the demineralization does not correspond to an etching pattern, and exhibits exposure of crystals with rods with rounded ends and less demineralization in the inter-prismatic spaces. Acid etching increased the presence of cracks and deep pores in the adamantine structure of the enamel with lesion. In moderate lesions, the mineral composition had higher content of Ca, P and Cl. Enamel with MIH, even on clinically intact adamantine surfaces, shows severe alterations in the ultrastructure and changes in ionic composition, which affect the acid etching pattern and may interfere with adhesion. PMID:26355892

  13. The magnitude of a human bite measured exactly at the molar Intercuspidation using FBG

    NASA Astrophysics Data System (ADS)

    Marin, Gabriela Costa; Milczewski, Maura S.; Abe, Ilda; Lopes, Stephani C. P. S.; Camargo, Elisa S.; Kalinowski, Hypolito J.

    2014-05-01

    The aim of the study is to develop a new punctual method to determine the human bite force, between uppers and lowers first molars, at the moment of occlusion in maximum intercuspation. Fibre optic Bragg gratings are encapsulated in an acetate splint made by casting of a volunteer lower dentition. Splint sensor was positioned into the mouth to be pressured with minimal occlusal interference. The transversal pressure on the FBG was acquired at the moment of before occlusion (free), occlusion and biting. The measured forces were 12N during occlusion and 28N bite force, between right uppers and lowers first molars.

  14. Upper molar distalization on palatal miniscrews: an easy to manage palatal appliance.

    PubMed

    Huanca Ghislanzoni, Luis Tomas; Piepoli, Claudio

    2012-05-01

    Upper molar distalization supported by miniscrews has become increasingly popular in the last years. A detailed clinical and lab procedure for the realization of a distalization appliance (fast back or distal jet) connected to miniscrews inserted in the anterior region of the palate is presented. A case report illustrates the use of a fast back appliance supported by miniscrews to correct the mesial shift of the molars and of the premolars as a consequence of an early loss of the maxillary deciduous canines. PMID:22583590

  15. Negative urine pregnancy test in a molar pregnancy: is it possible?

    PubMed

    Nigam, Aruna; Kumari, Archana; Gupta, Nidhi

    2014-01-01

    A urine pregnancy test is commonly used to detect pregnancy and is based on finding intact ?-human chorionic gonadotrophin (hCG) molecules in the urine by an immunoassay system. However, the significantly large amount of ?-hCG in molar pregnancy may paradoxically lead to a false-negative result due to a phenomenon known as the 'high dose hook effect'. A case of molar pregnancy with negative urine pregnancy test but very high serum ?-hCG is reported. Every obstetrician should be aware of this limitation in the presence of a high index of suspicion of gestational trophoblastic disease but negative urine pregnancy test. PMID:25378114

  16. [Radiographic and histological study of a case of apexification in a human molar].

    PubMed

    Sahli, C C

    1989-01-01

    A case of apexification in a lower right second molar is described. Radiographs demonstrate apical closure with a different morphological pattern from that of the lower left second molar. Following extraction, after 15 months, serial histologic sections show calcified tissue obturating the apical foramen, well adapted to the initial dentin and cementum walls. Inside some small areas containing connective tissue with capillaries can be observed. The histologic and radiographic observations indicate that apical closure occurs as a result of differentiation of periodontal apical cells. PMID:2640033

  17. Modified lingual split technique for extraction of impacted mandibular third molars.

    PubMed

    Lewis, J E

    1980-08-01

    Critical evaluation of existing chisel and bur techniques for removal of impacted mandibular third molars reveals a high incidence of complications. Both approaches require creation of a buccal defect immediately distal to the second molar for the insertion of an elevator, which may cause pocketing to occur postoperatively. The method described here minimizes periosteal reflection, almost completely avoids loss of bone, and effectively reduces the use of rotary instrumentation. The planning of the soft tissue flaps and bony cuts assists in primary wound closure, obliteration of dead space, and reduction of postoperative morbidity. PMID:6930459

  18. Primary Mandibular First Molar with Single Root and Single Canal: A Case Report of a Rare Morphology

    PubMed Central

    Bahrololoomi, Zahra; Ghafourifard, Roya; Soleimani, Ali Asghar

    2014-01-01

    Single rooted primary mandibular first molar is a rare developmental anomaly. Literatures reveal that failure of invagination of Hertwigs epithelial root sheath leads to this unusual root form. Thorough knowledge of root canal morphology and anatomical variations of primary teeth can help a pediatric dentist in successful root canal treatment. Hereby, we describe two cases of primary mandibular first molars with an unusual morphology as a single root called pyramidal molar. PMID:25628671

  19. Radiographic assessment of third molars development and it's relation to dental and chronological age in an Iranian population

    PubMed Central

    Monirifard, Mohamad; Yaraghi, Navid; Vali, Ava; Vali, Asana; Vali, Amrita

    2015-01-01

    Background: The aim of the present study was to estimate chronological age based on third molar development and to determine the association between dental age and third molar calcification stages. Materials and Methods: In this cross-sectional study, 505 digital panoramic radiographs of 223 males (44.2%) and 282 females (55.8%) between the age of 6 and 17 were selected from patients who were treated in Departments of Pediatrics and Orthodontics of Isfahan University of Medical Sciences between the years of 2009 and 2013. Correlation between chronological age and third molar development was analyzed with SPSS 21 using Spearman's Rank correlation coefficient, Chi-square test and multiple regression statistical tests (P < 0.05). Results: All third molars demonstrated a highly significant correlation with dental age (P < 0.001). The teeth showing the highest relationship with dental age were mandibular left third molar in males and mandibular right third molar in females (rs = 0.072). When multiple regression was used to predict dental age based on molar calcification stage, the only significant correlation was between maxillary left third molar in males (P < 0.05). There was no statistically significant correlation for any of third molars in females. Relationship between chronological age and molars development stage was significant in all age subgroups and in both gender (P < 0.001). Conclusion: Strong correlation was observed between left third molars and dental age in males. Results showed that third molar calcification stage can be used as an age predictor and in general mandibular teeth seems to be more reliable for this purpose in both genders and in all ages. PMID:25709677

  20. Partial hepatectomy in mice.

    PubMed

    Nevzorova, Y A; Tolba, R; Trautwein, C; Liedtke, C

    2015-04-01

    The surgical procedure of two-thirds partial hepatectomy (PH) in rodents was first described more than 80 years ago by Higgins and Anderson. Nevertheless, this technique is still a state-of-the-art method for the community of liver researchers as it allows the in-depth analysis of signalling pathways involved in liver regeneration and hepatocarcinogenesis. The importance of PH as a key method in experimental hepatology has even increased in the last decade due to the increasing availability of genetically-modified mouse strains. Here, we propose a standard operating procedure (SOP) for the implementation of PH in mice, which is based on our experience of more than 10 years. In particular, the SOP offers all relevant background information on the PH model and provides comprehensive guidelines for planning and performing PH experiments. We provide established recommendations regarding optimal age and gender of animals, use of appropriate anaesthesia and biometric calculation of the experiments. We finally present an easy-to-follow step-by-step description of the complete surgical procedure including required materials, critical steps and postoperative management. This SOP especially takes into account the latest changes in animal welfare rules in the European Union but is still in agreement with current international regulations. In summary, this article provides comprehensive information for the legal application, design and implementation of PH experiments. PMID:25835741

  1. Partial covariate adjusted regression.

    PubMed

    Sentrk, Damla; Nguyen, Danh V

    2009-02-01

    Covariate adjusted regression (CAR) is a recently proposed adjustment method for regression analysis where both the response and predictors are not directly observed (?entrk and Mller, 2005). The available data has been distorted by unknown functions of an observable confounding covariate. CAR provides consistent estimators for the coefficients of the regression between the variables of interest, adjusted for the confounder. We develop a broader class of partial covariate adjusted regression (PCAR) models to accommodate both distorted and undistorted (adjusted/unadjusted) predictors. The PCAR model allows for unadjusted predictors, such as age, gender and demographic variables, which are common in the analysis of biomedical and epidemiological data. The available estimation and inference procedures for CAR are shown to be invalid for the proposed PCAR model. We propose new estimators and develop new inference tools for the more general PCAR setting. In particular, we establish the asymptotic normality of the proposed estimators and propose consistent estimators of their asymptotic variances. Finite sample properties of the proposed estimators are investigated using simulation studies and the method is also illustrated with a Pima Indians diabetes data set. PMID:20126296

  2. Trigonometric Integrals via Partial Fractions

    ERIC Educational Resources Information Center

    Chen, H.; Fulford, M.

    2005-01-01

    Parametric differentiation is used to derive the partial fractions decompositions of certain rational functions. Those decompositions enable us to integrate some new combinations of trigonometric functions.

  3. Low partial discharge vacuum feedthrough

    NASA Technical Reports Server (NTRS)

    Benham, J. W.; Peck, S. R.

    1979-01-01

    Relatively discharge free vacuum feedthrough uses silver-plated copper conductor jacketed by carbon filled silicon semiconductor to reduce concentrated electric fields and minimize occurrence of partial discharge.

  4. Experts' understanding of partial derivatives using the partial derivative machine

    NASA Astrophysics Data System (ADS)

    Roundy, David; Weber, Eric; Dray, Tevian; Bajracharya, Rabindra R.; Dorko, Allison; Smith, Emily M.; Manogue, Corinne A.

    2015-12-01

    [This paper is part of the Focused Collection on Upper Division Physics Courses.] Partial derivatives are used in a variety of different ways within physics. Thermodynamics, in particular, uses partial derivatives in ways that students often find especially confusing. We are at the beginning of a study of the teaching of partial derivatives, with a goal of better aligning the teaching of multivariable calculus with the needs of students in STEM disciplines. In this paper, we report on an initial study of expert understanding of partial derivatives across three disciplines: physics, engineering, and mathematics. We report on the central research question of how disciplinary experts understand partial derivatives, and how their concept images of partial derivatives differ, with a focus on experimentally measured quantities. Using the partial derivative machine (PDM), we probed expert understanding of partial derivatives in an experimental context without a known functional form. In particular, we investigated which representations were cued by the experts' interactions with the PDM. Whereas the physicists and engineers were quick to use measurements to find a numeric approximation for a derivative, the mathematicians repeatedly returned to speculation as to the functional form; although they were comfortable drawing qualitative conclusions about the system from measurements, they were reluctant to approximate the derivative through measurement. On a theoretical front, we found ways in which existing frameworks for the concept of derivative could be expanded to include numerical approximation.

  5. Secular trend of earlier onset and decelerated development of third molars: evidence from Croatia.

    PubMed

    Sasso, Anja; Legovic, Mario; Mady Maricic, Barbara; Pavlic, Andrej; Spalj, Stjepan

    2015-04-01

    The purpose of this study was to evaluate the influence of the secular trend on development of third molars in 30 years period in Littoral region of Croatia. A total of 1103 panoramic radiographs of subjects aged from 6 to 18 years were analysed. First group comprised 531 panoramic radiographs (258 girls) taken from year period 1977 till 1979 and second group 572 radiographs (325 girls) taken from year period 2007 till 2009. Demirjian's method was used to determine the developmental stage of third molars. A secular trend in 30 years period was observed as earlier onset of third molars development in boys (6 months on average maxillary and 11 months mandibular) and girls (6 months for maxillary and 4 months for mandibular). Now-a-days, an increase in mineralisation for one Demirjian stage occurs at a slower pace of 5.2 months in boys and 3.4 in girls in maxilla and 2.3 or 2 months in mandible for boys and girls, respectively. The study showed a secular trend present as earlier onset but decelerated development of third molars in both genders and both jaws. PMID:25710780

  6. Evaluation of third molar development in the estimation of chronological age.

    PubMed

    Soares, Caio Belm Rodrigues Barros; Figueiroa, Jos Natal; Dantas, Renata Moura Xavier; Kurita, Lcio Mitsuo; Pontual, Andra dos Anjos; Ramos-Perez, Flvia Maria de Moraes; Perez, Danyel Elias da Cruz; Pontual, Maria Luiza dos Anjos

    2015-09-01

    The purpose of this study was to evaluate the correlation between chronological age and the degree of third molar mineralization by Demirjian's developmental stages (Demirjian et al., 1973) using panoramic radiography. From a total of 11.396 digital panoramic radiographs of patients from three oral radiology private clinics from the northeast region of Brazil, obtained from January to June 2009, 2097 radiographic images from patients aged between 6 and 22 years were selected. The images were analyzed individually by two obsevers using a 21-inch computer screen and Windows Picture and Fax Viewer. Reliability was achieved by intra- and interobserver evaluation, using the Kappa test. Chronological age, calcification stage, gender and third molar were interrelated using a multiple linear regression model, considering age as a response variable. There was reliability with Demirjian et al.'s developmental stage assesment, displaying a significant relationship between mineralization stages and patients' age (P<0.05). There was no significant difference between the average age and the calcification stage taking gender and localization of the third molar into consideration. It is possible to estimate chronological age based on Demirjian's stage of a third molar, regardless of gender and location. PMID:26164359

  7. Selenium:mercury molar ratios in bullfrog and leopard frog tadpoles from the northeastern United States.

    PubMed

    Burger, Joanna; Feinberg, Jeremy; Jeitner, Christian; Gochfeld, Michael; Donio, Mark; Pittfield, Taryn

    2014-06-01

    Vertebrates experience adverse effects from methylmercury, largely obtained through their food. Selenium has the potential to reduce the toxic effects of methylmercury (and vice versa). In this paper, we examine the selenium:mercury molar ratios in tadpoles (Lithobates sphenocephalus, Lithobates catesbeianus (formerly Rana), and a newly documented leopard frog species currently referred to as R. sp. nov.) and fully formed leopard frog metamorphs. There were no significant differences in metal levels between the two leopard frog species, and data were therefore combined. Selenium:mercury molar ratios varied from 19 to 38 for bullfrog tadpoles, from 16 to 330 for leopard frog tadpoles, and from 7 to 17 for leopard frog metamorphs. Leopard frog tadpoles with less than 45days exposure to field conditions had significantly higher molar ratios than other tadpoles and leopard frog metamorphs. There were significant locational differences for the molar ratios of bullfrogs, and leopard frog tadpoles with more than 45days of field exposure. At the sites where we were able to sample both leopard frog tadpoles and leopard frog metamorphs, there were significant differences between the two distinct life stages. Most of the variation in the ratio was accounted for by selenium levels, field sites, and exposure period. PMID:24585386

  8. STABILITY OF INGESTED METHYCELLULOSE IN THE RAT DETERMINED BY POLYMER MOLAR MASS MEASUREMENTS BY LIGHT SCATTERING

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methylcellulose (MC) is ingested by humans in food and pharmaceutical formulations. The functional properties of MC like those of other linear polymers depends primarily on polymer length or molar mass for largely linear polymers. Although many studies in animals and humans have shown complete exc...

  9. Genetic and Environmental Molarity and Modularity of Cognitive Functioning in 2-Year-Old Twins.

    ERIC Educational Resources Information Center

    Petrill, Stephen A.; Saudino, Kimberly S.; Wilkerson, Bessie; Plomin, Robert

    2001-01-01

    Investigated genetic and environmental influences on the similarity and differences among five tests of cognitive abilities in 1,958 pairs of same-sex twins born in 1994 in the United Kingdom. Results suggest a developmental trend from modularity to molarity when considered in relation to multivariate genetic results later in life that show that

  10. Sensibility and taste alterations after impacted lower third molar extractions. A prospective cohort study

    PubMed Central

    Ridaura-Ruiz, Lourdes; Valmaseda-Castelln, Eduard; Berini-Ayts, Leonardo; Gay-Escoda, Cosme

    2012-01-01

    Objectives: To determine the incidence, severity and duration of lingual tactile and gustatory function impairments after lower third molar removal. Study Design: Prospective cohort study with intra-subject measures of 16 patients undergoing lower third molar extractions. Sensibility and gustatory functions were evaluated in each subject preoperatively, one week and one month after the extraction, using Semmes-Weinstein monofilaments and 5 different concentrations of NaCl, respectively. Additionally, all patients filled a questionnaire to assess subjective perceptions. Results: Although patients did not perceive any sensibility impairments, a statistically significant decrease was detected when Semmes-Weinstein monofilaments. This alteration was present at one week after the surgical procedure and fully recovered one month after the extraction. There were no variations regarding the gustatory function. Conclusions: Lower third molar removal under local anesthesia may cause light lingual sensibility impairment. Most of these alterations remain undetected to patients. These lingual nerve injuries are present one week after the extraction and recover one month after surgery. The taste seems to remain unaffected after these procedures. Key words:Lingual nerve, third molar, nerve injury, paresthesia, surgical extraction PMID:22322520

  11. Is Overweight a Risk Factor for Adverse Events during Removal of Impacted Lower Third Molars?

    PubMed Central

    de Carvalho, Ricardo Wathson Feitosa; do Egito Vasconcelos, Belmiro Cavalcanti

    2014-01-01

    Being overweight is recognised as a significant risk factor for several morbidities; however, the experience of the dentistry faculties focusing on this population is still low. The aim of the present study was to determine the occurrence of adverse events during removal of impacted lower third molars in overweight patients. A prospective cohort study was carried out involving overweight patients subjected to surgical removal of impacted lower third molar as part of a line of research on third molar surgery. Predictor variables indicative of the occurrence of adverse events during surgery were classified by their demographic, clinical, radiographic, and surgical aspects. Descriptive and bivariate statistics were computed. In total, 140 patients fulfilled the eligibility criteria, and 280 surgeries were performed. Patients' mean age was 25.1 2.2 years, and the proportion of women to men was 3?:?1. Eight different adverse events during surgery were recorded. These events occurred in approximately 29.3% of cases and were significantly associated with predictor variables (P < 0.05). Excess weight is recognised as a risk factor for the high rate of adverse events in impacted third molar surgery. The study suggests that overweight patients are highly likely to experience morbidities. PMID:25548786

  12. Evaluation of root canal morphology of maxillary molars using cone beam computed tomography

    PubMed Central

    Alrahabi, Mothanna; Sohail Zafar, Muhammad

    2015-01-01

    Objectives: The success of endodontic treatment is based on cleaning and shaping of the root canals. The root canals have complex morphology and wide individual variations. The objective of this study was to analyze root canals morphology and existence of extra canals in maxillary molars in Saudi subpopulation. Methods: Freshly extracted maxillary first molars (n=100) were included in this study. All teeth were examined for morphology of roots, root canals and apical foramen by Cone Beam Computed Tomography (CBCT). The root canals configuration was classified using Vertuccis classification. Results: The majority of maxillary first molars (94%) were having three distinctly separated roots and 6% had four roots. Palatal and distobuccal roots were observed to contain one root canal (100%) and Vertuccis type I configuration. The mesiobuccal root had one (29.4%; type I) or two canals (70.6%; type II, III or IV). Conclusions: The occurrence of second canal in the mesiobuccal root of upper first molar is very much likely (>70%). The mesiobuccal roots are more likely to have Vertuccis type I or II configuration (>76%). The palatal and distobuccal roots always have a Vertuccis type I canal configuration. PMID:26101504

  13. Biodiesel from Canola Oil using a 1:1 Molar Mixture of Methanol and Ethanol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Canola oil was transesterified using an equimolar mixture of ethanol and methanol with potassium hydroxide (KOH) catalyst. Effect of catalyst concentration (0.5 to 1.5% wt/wt), molar ratio of equimolar mixture of ethanol and methanol (EMEM) to canola oil (3:1 to 12:1) and reaction temperature (25 t...

  14. Characterization of Alternan, a high molar mass polysaccharide from Leuconostoc mesenteroides, by FFF-MALS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Native alternan is a high molar mass homopolymer of D-glucose produced by some strains of the bacterium Lueconostoc mesenteroides. It consists of glucose units that alternate their linkages between alpha-(1-6) and alpha-(1-3) between glucosyl units. The glucose units contained in the polysaccharid...

  15. Complication rates in patients using absorbable collagen sponges in third molar extraction sockets: a retrospective study

    PubMed Central

    Cho, Hoon; Jung, Hwi-Dong; Kim, Bok-Joo; Kim, Chul-Hoon

    2015-01-01

    Objectives The purpose of this study is to retrospectively evaluate the postoperative complication rates for absorbable type-I collagen sponge (Ateloplug; Bioland) use in third molar extraction. Materials and Methods From January to August 2013, 2,697 total patients undergoing third molar extraction and type-I collagen sponge application in the Department of Oral and Maxillofacial Surgery at Yonsei University Dental Hospital (1,163 patients) and Dong-A University Hospital (1,534 patients) were evaluated in a retrospective study using their operation and medical records. Results A total of 3,869 third molars in 2,697 patients were extracted and the extraction sockets packed with type-I collagen sponges to prevent postoperative complications. As a result, the overall complication rate was 4.52%, with 3.00% experiencing surgical site infection (SSI), 1.14% showing alveolar osteitis, and 0.39% experiencing hematoma. Of the total number of complications, SSI accounted for more than a half at 66.29%. Conclusion Compared to previous studies, this study showed a relatively low incidence of complications. The use of type-I collagen sponges is recommended for the prevention of complications after third molar extraction. PMID:25741465

  16. Estimation of legal age using calcification stages of third molars in living individuals.

    PubMed

    Streckbein, Philipp; Reichert, Isabelle; Verhoff, Marcel A; Bödeker, Rolf-Hasso; Kähling, Christopher; Wilbrand, Jan-Falco; Schaaf, Heidrun; Howaldt, Hans-Peter; May, Andreas

    2014-12-01

    The increased number of adolescents and young adults with unknown or inaccurately given date of birth is a current issue in justice and legal medicine. The objective of this study was to determine the extent to which third molar calcification stages assessed on panoramic X-rays could be useful as additional criteria for forensic age estimation in living individuals, focusing on the legally important ages 17 and 18. In a retrospective multi-center study, the developmental stage of each individual's third molar was analyzed using Demirjian's scale in 2360 cases. Additionally, sex, age and ancestry were assessed. Individuals with the lowest calcification stage of all present molars in stage H were ≥18 years with a likelihood of ≥99.05% in the female (n=388), and ≥99.24% in the male (n=482) population. The lowest calcification stage of all present third molars proved to be useful as an additional reliable criterion for the determination of an age ≥18 years. PMID:25498932

  17. Caveats when Analyzing Ultra-high Molar Mass Polymers by SEC

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The analysis of ultra-high molar mass (M > 1 million g/mol) polymers via size-exclusion chromatography (SEC) presents a number of non-trivial challenges. Dissolution and full solvation may take days, as is the case for cellulose dissolution in non-complexing non degrading solvents; very low concent...

  18. Vienna-Chicago: the cultural transformation of the model system of the un-opposed molar.

    PubMed

    Luan, Xianghong; Diekwisch, Thomas G H

    2007-08-01

    The discussion over the roles of genes and environment on the phenotypical specification of organisms has held a central role in science philosophy since the late 19(th) century and has re-emerged in today's debate over genetic determinism and developmental plasticity. In fin-de-siecle Vienna, this debate coincided with a philosophical debate over empiricism/materialism versus idealism/vitalism. Turn-of-the-century Vienna's highly interdisciplinary environment was also the birthplace for the model system of the un-opposed molar. The un-opposed molar system features new tissue formation at the roots of teeth and tooth drift once opposing teeth are lost. The un-opposed molar model system was revived by a group of Viennese scientists who left Vienna during the Nazi period to address Vienna's questions about evolution and heredity and about genes and environment in Chicago's post-WWII scientific exile community. Here we are using the colorful history of the un-opposed molar to investigate the role of culture and method in the scientific evolution of a model system. PMID:17621674

  19. 40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 34 2013-07-01 2013-07-01 false SSV, CFV, and PDP molar flow rate calculations. 1065.642 Section 1065.642 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.642...

  20. 40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 33 2011-07-01 2011-07-01 false SSV, CFV, and PDP molar flow rate calculations. 1065.642 Section 1065.642 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.642...

  1. 40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 34 2012-07-01 2012-07-01 false SSV, CFV, and PDP molar flow rate calculations. 1065.642 Section 1065.642 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.642...

  2. 40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false SSV, CFV, and PDP molar flow rate calculations. 1065.642 Section 1065.642 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.642...

  3. Evaluation of chronological age based on third molar development in the Spanish population.

    PubMed

    Prieto, José L; Barbería, Elena; Ortega, Ricardo; Magaña, Concepción

    2005-11-01

    A cross-sectional study was carried out to assess chronological age estimation based on the stages of third lower molar development, following the eight stages (A-H) method of Demirjian et al. The final sample consisted of 1,054 orthopantomograms from Spanish individuals of known chronological age (range 14-21 years) and gender (462 males and 592 females). Results showed a stronger correlation for males (r(2)=0.54) than for females (r(2)=0.45). Root formation occurred earlier in males than females, in stages 5, 6 and 7. The mean difference between chronological and estimated age was -0.10 years (+/-1.23 SD) for left third molar, and -0.07 years (+/-1.22 SD) for right third molar, with slight variations regarding sex. Comparative tables are provided regarding medicolegal questions concerning age 18 prediction in the Spanish population, showing that legal age is reached in stage 7 (G) by women and in stage 8 (H) by men. No differences have been observed between sides (p<0.0001). Differences were observed between Spaniards and other previously studied populations. Third molar maturity takes place earlier in the Spanish than French-Canadian, Scandinavian, American, German, Japanese and South African populations and is more similar to US Hispanics in root development. PMID:15717200

  4. Endodontic management of a mandibular second molar with radix entomolaris: a case report

    PubMed Central

    Kandaswamy, Deivanayagam; Jayaprakash, Nachimuthu

    2014-01-01

    The presence of radix entomolaris (RE) in a mandibular first molar is a common occurrence in certain ethnic groups, but the presence of RE in a mandibular second molar is a rare occurrence. In the present case, RE was identified from preoperative radiographs and confirmed using cone-beam computed tomography (CBCT). The access cavity was modified to locate the RE. Cleaning and shaping were performed with nickel-titanium rotary instruments. Obturation was completed with gutta-percha cones using AH Plus (Dentsply Detrey GmbH) as sealer. From the CBCT axial images, the RE was determined to have a Type III curvature by the De Moor classification, Type B separate RE by the Carlsen and Alexandersen classification, and radiographically, a Type i image by the Wang classification. The presence of RE in the mandibular second molar makes it essential to anticipate and treat the distolingual root canal. This case report highlights the usefulness of CBCT for assessing RE in the mandibular second molar, which can help the clinician in making a confirmatory diagnosis and assessing the morphology of the root canal. PMID:24790927

  5. A COMPARISON OF LIME AND ORANGE PECTIN BY HPSGC WITH MOLAR MASS AND VISCOSITY DETECTION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pectin was acid extracted from lime albedo by microwave heating under pressure. Extraction times ranged from 1 to 10 minutes. Solubilized pectin was characterized for molar mass (M), rms radius of gyration (Rg) and intrinsic viscosity (IV) by HPSEC with online light scattering and viscosity detect...

  6. Molar Functional Relations and Clinical Behavior Analysis: Implications for Assessment and Treatment

    ERIC Educational Resources Information Center

    Waltz, Thomas J.; Follette, William C.

    2009-01-01

    The experimental analysis of behavior has identified several molar functional relations that are highly relevant to clinical behavior analysis. These include matching, discounting, momentum, and variability. Matching provides a broader analysis of how multiple sources of reinforcement influence how individuals choose to allocate their time and

  7. Rotation of the upper first molar in Class I, II, and III patients

    PubMed Central

    de Oliveira Viganó, Cristiane; da Rocha, Viviane Ekerman; Junior, Laerte Ribeiro Menezes; Paranhos, Luiz Renato; Ramos, Adilson Luiz

    2016-01-01

    Objective: The aim of this study was to evaluate the mean rotation of the upper first molar (U1st M) in cast models from nontreated patients presenting: Class I, skeletal Class II, dental Class II, and skeletal Class III, comparing with Class I orthodontically treated patients. Materials and Methods: One hundred cast models were evaluated with five groups, composed of nontreated Class I (n = 20), dental Class II (n = 20), skeletal Class II (n = 20), skeletal Class III (n = 20), and treated Class I (n = 20). Measurements were taken from photocopies of the upper arches. The angle formed between a line crossing the mesiopalatal and the distal-buccalcusps of the U1st M and a line traced on mid palatal junction were measured in all samples. Results: One-way variance analysis showed that dental Class II group presented great mean rotation of the 1st molar (x = 78.95°, SD = 6.19) (P < 0.05), and in 85% of the patients from this group this angle was higher than 73°. Conclusions: The skeletal Class II and skeletal Class III groups showed similar mean position of the 1st molar, presenting rotation in approximately 50% of the patients. It can be concluded that upper molar rotation occurs mainly in dental Class II patients and shows higher mesial rotation angle. PMID:27011741

  8. Efficacy of ultrasonic activation of NaOCl and orange oil in removing filling material from mesial canals of mandibular molars with and without isthmus

    PubMed Central

    Barreto, Mirela Sangoi; da Rosa, Ricardo Abreu; Santini, Manuela Favarin; Cavenago, Bruno Cavalini; Duarte, Marco Antônio Húngaro; Bier, Carlos Alexandre Souza; Só, Marcos Vinícius Reis

    2016-01-01

    ABSTRACT Objectives The aim of this study was to evaluate the volume of remaining filling material after passive ultrasonic irrigation (PUI) of sodium hypochlorite (NaOCl) and orange oil in mesial canals of mandibular molars, with and without isthmus. Material and Methods Thirty mesial roots of mandibular molars were divided according to the presence or absence of isthmus. Canals were prepared and filled (Micro-CT #1). Filling was removed using rotary instruments, and specimens were sub-divided into three groups according to the irrigation procedures: Conventional – conventional irrigation with NaOCl, PUI/NaOCl – PUI of NaOCl (three activations, 20 seconds each), and PUI/orange oil – PUI of orange oil (Micro-CT#2). Specimens were enlarged using the X2 and X3 ProTaper Next instruments and submitted to the same irrigation protocols (Micro-CT #3). Results No differences were found between the experimental groups in each stage of assessment (P>0.05). The volume of residual filling material was similar to those in Micro-CT #2 and Micro-CT #3, but lower than those observed in Micro-CT #1 (P<0.05). When groups were pooled according to the presence or absence of an isthmus, volume of residual filling material was higher in specimens presenting isthmus (P<0.05). Conclusions PUI of NaOCl or orange oil did not improve filling removal. Isthmus consists in an anatomical obstacle that impairs the removal of filling material. PMID:26200525

  9. A Cone-Beam Computed Tomographic Study on Mandibular First Molars in a Chinese Subpopulation

    PubMed Central

    Ma, Yue; Han, Ting; Chen, Xinyu; Wan, Fang; Lu, Yating; Yan, Songhe; Wang, Yan

    2015-01-01

    The purpose of this study was to conduct a cone-beam computed tomographic (CBCT) investigation on the root and canal configuration of the mandibular first molars, especially the morphology of the disto-lingual (DL) root, in a Chinese subpopulation. A total of 910 CBCT images of the mandibular first molars were collected from 455 patients who underwent CBCT examinations as a preoperative assessment for implants or orthodontic treatment. The following information was analyzed and evaluated: tooth position, gender, root and root canal number per tooth, root canal type of the mesial root(s) and distal root(s), angle of the DL root canal curvature, distance between two distal canal orifices in the teeth with DL root, and angle of disto-buccal canal orifice–disto-lingual canal orifice–mesio-lingual canal orifice (DB-DL-ML). Most of the mandibular first molars (64.9%, n = 591) had two roots with three root canals, and most of the mesial root canals (87.7%, n = 798) were type VI. The prevalence of the DL root was 22.1% (n = 201). The right side had a higher prevalence of DL root than the left side (p<0.05). Additionally, the curvature of the DL root canal were greater in the bucco-lingual (BL) orientation (30.10°±14.02°) than in the mesio-distal (MD) orientation (14.03°± 8.56°) (p<0.05). Overall there was a high prevalence of DL root in the mandibular first molars, and most of the DL roots were curved in different degrees. This study provided detailed information about the root canal morphology of the mandibular first molars in a Chinese subpopulation. PMID:26241480

  10. Third molar development by measurements of open apices in an Italian sample of living subjects.

    PubMed

    De Luca, Stefano; Pacifici, Andrea; Pacifici, Luciano; Polimeni, Antonella; Fischetto, Sara Giulia; Velandia Palacio, Luz Andrea; Vanin, Stefano; Cameriere, Roberto

    2016-02-01

    The aim of this study is to analyse the age-predicting performance of third molar index (I3M) in dental age estimation. A multiple regression analysis was developed with chronological age as the independent variable. In order to investigate the relationship between the I3M and chronological age, the standard deviation and relative error were examined. Digitalized orthopantomographs (OPTs) of 975 Italian healthy subjects (531 female and 444 male), aged between 9 and 22 years, were studied. Third molar development was determined according to Cameriere et al. (2008). Analysis of covariance (ANCOVA) was applied to study the interaction between I3M and the gender. The difference between age and third molar index (I3M) was tested with Pearson's correlation coefficient. The I3M, the age and the gender of the subjects were used as predictive variable for age estimation. The small F-value for the gender (F = 0.042, p = 0.837) reveals that this factor does not affect the growth of the third molar. Adjusted R(2) (AdjR(2)) was used as parameter to define the best fitting function. All the regression models (linear, exponential, and polynomial) showed a similar AdjR(2). The polynomial (2nd order) fitting explains about the 78% of the total variance and do not add any relevant clinical information to the age estimation process from the third molar. The standard deviation and relative error increase with the age. The I3M has its minimum in the younger group of studied individuals and its maximum in the oldest ones, indicating that its precision and reliability decrease with the age. PMID:26706411

  11. Negotiability of Second Mesiobuccal Canals in Maxillary Molars Using a Reciprocating System.

    PubMed

    Zuolo, Mario Luis; Carvalho, Maria Cristina; De-Deus, Gustavo

    2015-11-01

    The aim of this prospective case series report was to assess the frequency in which the Reciproc R25 instrument (VDW, Munich, Germany) is able to scout and reach the full working length (WL) in second mesiobuccal (MB2) canals from maxillary molars. Conventional hand file negotiation was used as the reference technique for comparison. Maxillary molars (270 first molars and 71 second molars) were included in this study. After local anesthesia, the tooth was isolated with a rubber dam, and traditional straight-line access was made. After locating both first mesiobuccal and MB2 canals, patients were randomly assigned to one of the experimental groups (conventional hand filing preparation or R25 Reciproc preparation). All cases in which the hand files (G1) and R25 instrument (G2) were able to reach the fully electronically determined WL were classified as "reaching full WL" (RFWL). All cases in which the hand files (G1) and R25 instrument (G2) were unable to negotiate the full-length canal were classified as "not reaching full WL" (NRFWL). The number of root canals classified as RFWL and NRFWL from both groups were recorded and tabulated on an Excel data sheet (Microsoft, Redmond, WA). The frequency distributions (%) of root canals classified as RFWL and NRFWL were compared with overall-treated canals and for each treatment approach (hand file and R25 instrument) using a Pearson chi-square test. In group 1, the hand file approach reached the full WL in 57.48% of cases, whereas in group 2 the R25 instrument reached the full WL in 85.63% of cases. Three file separations occurred in each group while negotiating the MB2 canal. According to this study, the R25 instrument was 32% more effective when compared with hand files in scouting and negotiating MB2 canals in maxillary first and second molars. There was no difference with regard to file separation when comparing both preparation techniques. PMID:26443438

  12. Sex assessment efficacy of permanent maxillary first molar cusp dimensions in Indians

    PubMed Central

    Yadav, Achla Bharti; Angadi, Punnya V.; Yadav, Sumit Kumar

    2015-01-01

    Background: The human first maxillary molar provides clues about evolution and is functionally important. It has four main cusps, and each cusp has an independent growth pattern and different evolutionary background. Though less explored, the analysis based on measurement of each cusp appears to be more meaningful biologically than conventional measurements of the whole crown. Aim: This study aimed to demonstrate the extent of sexual dimorphism in permanent maxillary first molar cusp diameters and their potential utility in sex prediction among Indians using logistic regression analysis (LRA). Materials and Methods: The mesiodistal and buccolingual (BL) crown diameters along with cusp dimensions and cusp indices of right maxillary first molar were measured in an Indian sample (149 males, 151 females; age range of 18–30 years). The possible sex dimorphism in these parameters was evaluated, and LRA was performed to ascertain their usefulness in sex prediction. Results: BL crown dimension and the hypocone (distolingual) cusp showed the highest sexual dimorphism. The combination of metacone and hypocone, i.e., distal cusp diameters among cusp parameters showed the highest accuracy (61.3%). While, on combining all the crown and cusp diameters together the overall accuracy was raised (64.3%). Conclusion: This study supports the ontogeny hypothesis suggesting that early-forming mesial cusps demonstrate less sexual variation as compared to subsequently formed distal cusps in the maxillary molar. Though the sex identification accuracy for cusp diameters of the permanent maxillary first molar in Indians is relatively moderate (≈61%), it can be used as an adjunct for sexing of adult Indians in forensic contexts. PMID:26681853

  13. Coronectomy of Deeply Impacted Lower Third Molar: Incidence of Outcomes and Complications after One Year Follow-Up

    PubMed Central

    Heijsters, Guido; Salem, Ahmed Sobhy; Van Slycke, Sarah; Schepers, Serge; Politis, Constantinus; Vrielinck, Luc

    2015-01-01

    ABSTRACT Objectives The purpose of present study was to assess the surgical management of impacted third molar with proximity to the inferior alveolar nerve and complications associated with coronectomy in a series of patients undergoing third molar surgery. Material and Methods The position of the mandibular canal in relation to the mandibular third molar region and mandibular foramen in the front part of the mandible (i.e., third molar in close proximity to the inferior alveolar nerve [IAN] or not) was identified on panoramic radiographs of patients scheduled for third molar extraction. Results Close proximity to the IAN was observed in 64 patients (35 females, 29 males) with an impacted mandibular third molar. Coronectomy was performed in these patients. The most common complication was tooth migration away from the mandibular canal (n = 14), followed by root exposure (n = 5). Re-operation to remove the root was performed in cases with periapical infection and root exposure. Conclusions The results indicate that coronectomy can be considered a reasonable and safe treatment alternative for patients who demonstrate elevated risk for injury to the inferior alveolar nerve with removal of the third molars. Coronectomy did not increase the incidence of damage to the inferior alveolar nerve and would be safer than complete extraction in situations in which the root of the mandibular third molar overlaps or is in close proximity to the mandibular canal. PMID:26229580

  14. Impacted Mandibular Third Molars: Review of Literature and a Proposal of a Combined Clinical and Radiological Classification

    PubMed Central

    Santosh, P

    2015-01-01

    Tooth impaction is a pathological situation where a tooth fails to attain its normal functional position. Impacted third molars are commonly encountered in routine dental practice. The impaction rate is higher for third molars when compared with other teeth. The mandibular third molar impaction is said to be due to the inadequate space between the distal of the second mandibular molar and the anterior border of the ascending ramus of the mandible. Impacted teeth may remain asymptomatic or may be associated with various pathologies such as caries, pericoronitis, cysts, tumors, and also root resorption of the adjacent tooth. Even though various classifications exist in the literature, none of those address the combined clinical and radiologic assessment of the impacted third molar. Literature search using the advanced features of various databases such as PubMed, Scopus, Embase, Google Scholar, Directory of Open Access Journals and Cochrane electronic databases was carried out. Keywords like impaction, mandibular third molar, impacted mandibular third molar, complications, anatomy, inferior alveolar nerve injury, lingual nerve injury were used to search the databases. A total of 826 articles were screened, and 50 articles were included in the review which was obtained from 1980 to February 2015. In the present paper, the authors have proposed a classification based on clinical and radiological assessment of the impacted mandibular third molar. PMID:26229709

  15. Prediction of Setschenow constants of N-heteroaromatics in NaCl solutions based on the partial charge on the heterocyclic nitrogen atom.

    PubMed

    Yang, Bin; Li, Zhongjian; Lei, Lecheng; Sun, Feifei; Zhu, Jingke

    2016-02-01

    The solubilities of 19 different kinds of N-heteroaromatic compounds in aqueous solutions with different concentrations of NaCl were determined at 298.15 K with a UV-vis spectrophotometry and titration method, respectively. Setschenow constants, K s, were employed to describe the solubility behavior, and it is found that the higher ring numbers of N-heteroaromatics gave rise to the lower values of K s. Moreover, K s showed a good linear relationship with the partial charge on the nitrogen atom (Q N) for either Q N > 0 or Q N < 0 N-heteroaromatics. It further revealed that Q N was well-matched in the prediction of salting-out effect for N-heteroaromatics compared to the conventional descriptors such as molar volume (V H) and the octanol-water partition coefficient (K ow). The heterocyclic N in N-heteroaromatics may interact with Na(+) ions in NaCl solution for Q N < 0 and with Cl(-) for Q N > 0. PMID:26490915

  16. Partial Pressures of Te2 and Thermodynamic Properties of Ga-Te System

    NASA Technical Reports Server (NTRS)

    Su, Ching-Hua; Curreri, Peter A. (Technical Monitor)

    2001-01-01

    The partial pressures of Te2 in equilibrium with Ga(1-x)Te(x) samples were measured by optical absorption technique from 450 to 1100 C for compositions, x, between 0.333 and 0.612. To establish the relationship between the partial pressure of Te, and the measured optical absorbance, the calibration runs of a pure Te sample were also conducted to determine the Beer's Law constants. The partial pressures of Te2 in equilibrium with the GaTe(s) and Ga2Te3(s)compounds, or the so-called three-phase curves, were established. These partial pressure data imply the existence of the Ga3Te4(s) compound. From the partial pressures of Te2 over the Ga-Te melts, partial molar enthalpy and entropy of mixing for Te were derived and they agree reasonable well with the published data. The activities of Te in the Ga-Te melts were also derived from the measured partial pressures of Te2. These data agree well with most of the previous results. The possible reason for the high activity of Te measured for x less than 0.60 is discussed.

  17. Restoration of a vertical alveolar bone defect by orthodontic relocation of a mesially impacted mandibular first molar.

    PubMed

    Kim, Sung-Jin; Kim, Jin-Wook; Choi, Tae-Hyun; Lee, Kee-Joon

    2015-04-01

    An impacted mandibular first molar tends to cause serious bone defects of the adjacent teeth. When choosing between the 2 typical treatment options-extraction or orthodontic relocation of the impacted tooth-the decision should be based on assessment of the prognosis. A 22-year-old man with severe mesioangulation and impaction of the mandibular first molar and a related vertical bone defect on the distal side of the second premolar was treated with extraction of the second molar and orthodontic relocation of the first molar with a retromolar miniscrew. Comprehensive orthodontic treatment involving premolar extraction was conducted. Strategic extraction of the molar and adequate orthodontic movement helped to restore the bone structure on the affected side. This case report suggests the effectiveness of restoration of bone defects by using viable periodontal tissues around the impacted tooth for the longevity of the periodontium. PMID:25836343

  18. Intrusion of supraerupted maxillary molar using a high interim restoration on the defective opposing tooth: a clinical report.

    PubMed

    Tao, Ye; Luo, Xiao Ping; Bartlett, David W

    2015-04-01

    Wear, extraction, or fracture of all or part of a mandibular first molar can lead to the supraeruption of the opposing maxillary molar, resulting in occlusal interference and lack of restoration space. This report describes a method to gain sufficient vertical space for permanent restoration. A direct composite resin restoration was placed on the occlusal surface of a lower molar, intentionally making the interim restoration high and intruding the maxillary molar. After 6 weeks, the extruded tooth returned to the desired position, and functional occlusion was restored, enabling a ceramic restoration on the mandibular molar. No marked adverse sensory reaction was reported in this therapeutic process, and no deleterious signs were detected in the teeth, periodontium, or temporomandibular joints. The simple treatment type was effective, noninvasive, and time saving, while also preserving maximum tooth structures. PMID:24975824

  19. Analysis of midpalatal miniscrew-assisted maxillary molar distalization patterns with simultaneous use of fixed appliances: A preliminary study.

    PubMed

    Mah, Su-Jung; Kim, Ji-Eun; Ahn, Eun Jin; Nam, Jong-Hyun; Kim, Ji-Young; Kang, Yoon-Goo

    2016-01-01

    Skeletal anchorage-assisted upper molar distalization has become one of the standard treatment modalities for the correction of Class II malocclusion. The purpose of this study was to analyze maxillary molar movement patterns according to appliance design, with the simultaneous use of buccal fixed orthodontic appliances. The authors devised two distinct types of midpalatal miniscrew-assisted maxillary molar distalizers, a lingual arch type and a pendulum type. Fourteen patients treated with one of the two types of distalizers were enrolled in the study, and the patterns of tooth movement associated with each type were compared. Pre- and post-treatment lateral cephalograms were analyzed. The lingual arch type was associated with relatively bodily upper molar distalization, while the pendulum type was associated with distal tipping with intrusion of the upper molar. Clinicians should be aware of the expected tooth movement associated with each appliance design. Further well designed studies with larger sample sizes are required. PMID:26877983

  20. Analysis of midpalatal miniscrew-assisted maxillary molar distalization patterns with simultaneous use of fixed appliances: A preliminary study

    PubMed Central

    Mah, Su-Jung; Kim, Ji-Eun; Ahn, Eun Jin; Nam, Jong-Hyun; Kim, Ji-Young

    2016-01-01

    Skeletal anchorage-assisted upper molar distalization has become one of the standard treatment modalities for the correction of Class II malocclusion. The purpose of this study was to analyze maxillary molar movement patterns according to appliance design, with the simultaneous use of buccal fixed orthodontic appliances. The authors devised two distinct types of midpalatal miniscrew-assisted maxillary molar distalizers, a lingual arch type and a pendulum type. Fourteen patients treated with one of the two types of distalizers were enrolled in the study, and the patterns of tooth movement associated with each type were compared. Pre- and post-treatment lateral cephalograms were analyzed. The lingual arch type was associated with relatively bodily upper molar distalization, while the pendulum type was associated with distal tipping with intrusion of the upper molar. Clinicians should be aware of the expected tooth movement associated with each appliance design. Further well designed studies with larger sample sizes are required. PMID:26877983