Science.gov

Sample records for partial molar volume

  1. Determination of partial molar volumes from free energy perturbation theory†

    PubMed Central

    Vilseck, Jonah Z.; Tirado-Rives, Julian

    2016-01-01

    Partial molar volume is an important thermodynamic property that gives insights into molecular size and intermolecular interactions in solution. Theoretical frameworks for determining the partial molar volume (V°) of a solvated molecule generally apply Scaled Particle Theory or Kirkwood–Buff theory. With the current abilities to perform long molecular dynamics and Monte Carlo simulations, more direct methods are gaining popularity, such as computing V° directly as the difference in computed volume from two simulations, one with a solute present and another without. Thermodynamically, V° can also be determined as the pressure derivative of the free energy of solvation in the limit of infinite dilution. Both approaches are considered herein with the use of free energy perturbation (FEP) calculations to compute the necessary free energies of solvation at elevated pressures. Absolute and relative partial molar volumes are computed for benzene and benzene derivatives using the OPLS-AA force field. The mean unsigned error for all molecules is 2.8 cm3 mol−1. The present methodology should find use in many contexts such as the development and testing of force fields for use in computer simulations of organic and biomolecular systems, as a complement to related experimental studies, and to develop a deeper understanding of solute–solvent interactions. PMID:25589343

  2. Partial molar volume of L-Valine in water under high pressure

    NASA Astrophysics Data System (ADS)

    Sawamura, Seiji

    2013-06-01

    Partial molar volume of L-valine in water was estimated up to 400 MPa from pressure coefficient of the solubility of the solute and molar volume of solid valine. The former was measured in a previous paper and the latter was measured in this article using a piston-cylinder typed cell. The partial molar volume increased with pressure and a maximum was observed around 250 MPa. It was compared with other amino acids.

  3. Partial molar volumes of hydrogen and deuterium in niobium, vanadium, and tantalum

    SciTech Connect

    Peterson, D.T.; Herro, H.M.

    1983-01-01

    The partial molar volumes of hydrogen and deuterium were measured in vanadium, niobium, and tantalum by a differential pressure technique. One-half of an electrolytically charged sample plat was compressed between hardened steel blocks in a hydraulic press. The activity of hydrogen in the hig pressure region was raised and caused hydrogen to diffuse into the low pressure region. The partia molar volume was calculated from the ratio of the hydrogen concentrations in the high and low pressure regions of the sample. Small isotope effects were found in the partial molar volume. Hydrogen had the larger volume in niobium and tantalum, but the reverse was true in vanadium.

  4. Partial molar volumes of isoniazid solutions in aqueous-ethanol mixtures at 298.15 K

    NASA Astrophysics Data System (ADS)

    Deosarkar, S. D.; Sawale, R. T.; Tawde, P. D.; Kalyankar, T. M.

    2015-02-01

    Densities (ρ) of antitubercular drug isoniazid solutions in water, aqueous-ethanol (20-80 vol % EtOH) and in pure ethanol at 298.15 K with different molar concentrations (0.01-0.16 mol dm-3) were measured. Experimental density data were used to calculate apparent molar volumes (φ v ) of isoniazid in different media. The φ v data were fitted to Massons relation and partial molar volumes (φ{/v 0}) of drug for infinitely dilute solution were determined for each solution. Experimental and derived properties were interpreted in terms of drug-solvent molecular interactions and structural fittings in studied systems.

  5. 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.

  6. Quadrupole terms in the Maxwell equations: Born energy, partial molar volume, and entropy of ions.

    PubMed

    Slavchov, Radomir I; Ivanov, Tzanko I

    2014-02-21

    A new equation of state relating the macroscopic quadrupole moment density Q to the gradient of the field ∇E in an isotropic fluid is derived: Q = αQ(∇E - U∇·E/3), where the quadrupolarizability αQ is proportional to the squared molecular quadrupole moment. Using this equation of state, a generalized expression for the Born energy of an ion dissolved in quadrupolar solvent is obtained. It turns out that the potential and the energy of a point charge in a quadrupolar medium are finite. From the obtained Born energy, the partial molar volume and the partial molar entropy of a dissolved ion follow. Both are compared to experimental data for a large number of simple ions in aqueous solutions. From the comparison the value of the quadrupolar length LQ is determined, LQ = (αQ/3ɛ)(1/2) = 1-4 Å. Data for ion transfer from aqueous to polar oil solution are analyzed, which allowed for the determination of the quadrupolarizability of nitrobenzene. PMID:24559353

  7. 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

  8. 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.

  9. 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.

  10. 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}.

  11. Apparent molar and partial molar volumes of aqueous ceric ammonium nitrate solutions at 20, 25, 30, and 35°C

    NASA Astrophysics Data System (ADS)

    Deosarkar, S. D.; Wanale, S. G.; Shelke, M. P.

    2014-07-01

    Present paper reports the measured densities (ρ) and refractive indices ( n D) of aqueous solutions of ceric ammonium nitrate (CAN) at 20, 25, 30, and 35°C in different concentrations of solution. Apparent molar volumes (φv) have been calculated from the density data at different temperatures and fitted to Massons relation to get limiting partial molar volumes (ϕ{v/0}) of CAN. Refractive index data were fitted to linear dependence over concentration of solutions and values of constant K and n {D/0} for different temperatures were evaluated. Specific refractions ( R D) of solutions were calculated from the refractive index and density data. Concentration and temperature effects on experimental and derived properties have been discussed in terms of structural interactions.

  12. 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.

  13. Solubility and partial molar volumes of naphthalene, phenanthrene, benzoic acid, and 2-methoxynaphthalene in supercritical carbon dioxide

    SciTech Connect

    Goenenc, Z.S.; Akman, U. |; Sunol, A.K.

    1995-07-01

    The effect of temperature, pressure, and supercritical fluid density on the retention and solubility in the mobile phase of solutes in supercritical fluid chromatography was investigated. New retention data for naphthalene, phenanthrene, benzoic acid, and 2-methoxynaphthalene were obtained as a function of pressure at different temperatures. Most of the data were taken near the critical region of the fluid phase where the anomalities such as enhanced solubility/selectivity and retrogate behavior are expected. These data were then used to compare two different approaches for modeling the pressure dependence of solute retention on the column. In these approaches, mobile-phase partial molar volumes of the solutes were determined either from bulk solubility data or from infinite-dilution fugacity coefficients. In both approaches, an integrated expression for the change of retention with pressure was utilized to explicitly reveal the nature of interactions between the stationary phase and the solute. The approach that utilizes the infinite-dilution fugacity coefficient predicts the pressure dependence of solute retention more accurately, especially for solutes that are substantially soluble in the mobile phase near the critical point of the mobile phase. Relationships between the pressure and temperature dependence of the solute solubility in the mobile phase and the retention of solutes on the column were also investigated.

  14. Octanol-Water Partition Coefficient from 3D-RISM-KH Molecular Theory of Solvation with Partial Molar Volume Correction.

    PubMed

    Huang, WenJuan; Blinov, Nikolay; Kovalenko, Andriy

    2015-04-30

    The octanol-water partition coefficient is an important physical-chemical characteristic widely used to describe hydrophobic/hydrophilic properties of chemical compounds. The partition coefficient is related to the transfer free energy of a compound from water to octanol. Here, we introduce a new protocol for prediction of the partition coefficient based on the statistical-mechanical, 3D-RISM-KH molecular theory of solvation. It was shown recently that with the compound-solvent correlation functions obtained from the 3D-RISM-KH molecular theory of solvation, the free energy functional supplemented with the correction linearly related to the partial molar volume obtained from the Kirkwood-Buff/3D-RISM theory, also called the "universal correction" (UC), provides accurate prediction of the hydration free energy of small compounds, compared to explicit solvent molecular dynamics [ Palmer , D. S. ; J. Phys.: Condens. Matter 2010 , 22 , 492101 ]. Here we report that with the UC reparametrized accordingly this theory also provides an excellent agreement with the experimental data for the solvation free energy in nonpolar solvent (1-octanol) and so accurately predicts the octanol-water partition coefficient. The performance of the Kovalenko-Hirata (KH) and Gaussian fluctuation (GF) functionals of the solvation free energy, with and without UC, is tested on a large library of small compounds with diverse functional groups. The best agreement with the experimental data for octanol-water partition coefficients is obtained with the KH-UC solvation free energy functional.

  15. Partial molar volumes of NiO and CoO liquids: implications for the pressure dependence of metal-silicate partitioning

    NASA Astrophysics Data System (ADS)

    Courtial, Philippe; Gottsmann, Joachim; Holzheid, Astrid; Dingwell, Donald B.

    1999-08-01

    Volumetric measurements have been conducted on 7 Ni- and Co-containing sodium disilicate liquids within a compositional range varying from 0 to 9 mol% of NiO and from 0 to 23 mol% of CoO and over a large temperature interval (i.e., above their respective glass transition temperature and up to at least 1473 K). Their molar volumes and thermal expansivities have been determined by combining high-temperature measurements using the Pt-based double-bob Archimedean method and low-temperature measurements using the method described by Webb et al. [S.L. Webb, R. Knoche, D.B. Dingwell, Determination of silicate liquid thermal expansivity using dilatometry and calorimetry, Eur. J. Mineral. 4 (1992) 95-104] based on an assumed equivalence of the relaxation of volume and enthalpy at the glass transition. The molar volume of the present liquids decreases with increasing NiO and CoO contents and the Co-containing liquids exhibit a greater molar volume than the Ni-containing liquids at equivalent molar concentrations. The present results were analysed using a regression equation from which the partial molar volume of NiO and CoO liquids was obtained by the least squares method. This procedure yields partial molar volumes valid over the entire temperature range of 11.506 ± 0.687 and 14.884 ± 0.149 cm 3/mol and temperature derivatives of 2.684 ± 1.6 × 10 -3 and 1.441 ± 0.4 × 10 -3 cm 3/mol K, respectively for NiO and CoO at 800 K. The behavior of M-Fe metal-silicate exchange partition coefficient (M = Ni, Co), based on present molar volume determinations, has been estimated as a function of pressure over a wide temperature range. The metal-silicate exchange partition coefficients of both Ni and Co decrease with increasing pressure within the entire temperature range considered in this study (i.e., 800-3000 K).

  16. Partial Molar Volumes and Viscosity B-Coefficients of Nicotinamide in Aqueous Resorcinol Solutions at T = (298.15, 308.15, and 318.15) K

    NASA Astrophysics Data System (ADS)

    Roy, Mahendra Nath; Banerjee, Ashis; Roy, Pran Kumar

    2009-04-01

    Partial molar volumes {( {φ _v^o} )} and viscosity B-coefficients for nicotinamide in (0.00, 0.05, 0.10, 0.15, and 0.20) mol·dm-3 aqueous resorcinol solutions have been determined from solution density and viscosity measurements at (298.15, 308.15, and 318.15) K as a function of the concentration of nicotinamide (NA). Here the relation {φ v^o =a_0 +a1 T+a2 T2}, has been used to describe the temperature dependence of the partial molar volume {φ _v^o }. These results and the results obtained in pure water were used to calculate the standard volumes of transfer {Δ φ v^o } and viscosity B-coefficients of transfer of nicotinamide from water to aqueous resorcinol solutions to study various interactions in the ternary solutions. The partial molar volume {( {φ v^o})} and experimental slopes obtained from the Masson equation have been interpreted in terms of solute-solvent and solute-solute interactions, respectively. The viscosity data have been analyzed using the Jones-Dole equation, and the derived parameters B and A have also been interpreted in terms of solute-solvent and solute-solute interactions, respectively, in the ternary solutions.The structure making or breaking ability of nicotinamide has been discussed in terms of the sign of {( {δ 2φ _v^o /δ T2})_P}. The activation parameters of viscous flow for the ternary solutions studied were also calculated and explained by the application of transition state theory.

  17. New Measurements of the Densities of Copper- and Nickel-Sulfide Liquids and Preliminary Estimates of the Partial Molar Volumes of Cu, Ni, S and O

    NASA Astrophysics Data System (ADS)

    Kress, V. C.; Ghiorso, M. S.

    2001-12-01

    We present the results of density measurements in Ni- and Cu-sulfide liquids. Density measurements were performed in-situ at 1250° C under controlled-atmosphere conditions using the modified single-bob (MSB) Archimedean method. The MSB consists of a ~2 mm diameter rod with a ~6 mm long ~7 mm diameter cylindrical bob attached ~7 mm from the base of the rod. The bob and crucible were constructed from Yt stabilized zirconia to minimize reaction with the corrosive sulfide liquid. Zirconia density at temperature was calibrated against the known density of molten Cu metal (Drotning 1981, High Temp-High Press 13: 441-458). Density was determined by measuring buoyancy as a function of immersed volume. Buoyancy was measured with a 0.1 mg resolution analytical balance interfaced with a computer. The crucible is mounted on a micrometer "elevator" allowing regulation of immersion with .005 mm resolution. Temperature was measured with an S-type thermocouple in contact with the bottom of the crucible. We explored log(fO2) from -8.2 to -12.6 and log(fS2) from -1.9 to -3.3. Five measurements have been made so far. Cu-sulfide densities range from 6.32 to 6.36 g/cc and were reproducible to +/-0.7%. Measured Ni-sulfide densities were lower, ranging from 5.27 to 5.79 g/cc. Wetting problems in Ni-sulfide compositions made these measurements more difficult. Reproducibility in Ni-sulfide melts was roughly +/-5%. Measured density values were used to regress preliminary partial molar volumes of sulfide liquids in the Cu-Ni-S-O system. A linear least squares fit was derived from the five density measurements along with the densities of pure molten Cu (Drotning 1981, ibid.) and Ni (Nasch 1995, Phys Chem Liq 29: 43-58) at 1250° C. Melt compositions under experimental conditions were estimated using the thermodynamic model of Kress (submitted). The molar volume of the system (V) can be expressed as: V = 8.18 XCu + 7.38 XNi + 30.33 XS where XI is the mole fraction of component i. Oxygen

  18. 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 (ρ) and viscosity (η) 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 (φv) of salts were calculated from density data and fitted to Massons relation and partial molar volumes (φ{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.

  19. Molar volumes and densities of minerals

    USGS Publications Warehouse

    Robie, Richard A.; Bethke, Philip M.

    1962-01-01

    These tables present critically chosen "best values" for the density and molar volume of selected mineral compounds. No attempt was made to be all-inclusive; rather we have tried to present data for chemically and physically well-defined phases for which the molar volume and/or density was knovvn to the order of 0. 2 percent.

  20. Molar volume and thermal expansion of glaucophane

    NASA Astrophysics Data System (ADS)

    Jenkins, David M.; Corona, Juan-Carlos

    2006-08-01

    The molar volume of glaucophane [Na2Mg3Al2Si8O22(OH)2] has been determined in this study by correcting synthetic glaucophane-rich amphiboles made in the system Na2O-MgO-Al2O3-SiO2-H2O for very small deviations from ideal glaucophane composition using recent volume data on key amphibole components. The derived unit-cell volume for end-member glaucophane is 862.7±1.6 Å3, which gives a molar volume of 259.8±0.5 cm3/mol and a calculated density of 3.016±0.006 g/cm3. This value has been corroborated through an essentially independent method by correcting the volumes of natural sodic amphiboles reported in the literature for non-glaucophane components, particularly including calcium-rich components, to yield a value of 861.2±1.9 Å3. The unit-cell volume derived from the synthetic amphiboles, which is considered here to be more reliable, is somewhat smaller than that reported previously in the literature. A thermal expansion (αV) at 298 K of 1.88±0.06×10-5/K was derived from unit-cell volumes measured in the range of 25-500°C for a synthetic glaucophane sample, which is noticeably smaller than previously reported.

  1. [Partial molar pregnancy. A case report and literature review].

    PubMed

    Morales García, Víctor; Bautista Gómez, Esperanza; Vásquez Santiago, Edmundo; Santos Pérez, Ursula

    2011-07-01

    We report the case of a 17 year old patient with partial molar pregnancy and coexistent live fetus of 13 gestational weeks diagnosed by ultrasound, which required the termination of pregnancy for maternal decompensation. PMID:21966838

  2. 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 1550°C, 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 Mössbauer 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 Mössbauer spectra of glasses. Specifically, this study confirms that the 57Fe Mössbauer 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

  3. 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…

  4. Partial Molar Volumes, Viscosity B-Coefficients, and Adiabatic Compressibilities of Sodium Molybdate in Aqueous 1,3-Dioxolane Mixtures from 303.15 to 323.15 K

    NASA Astrophysics Data System (ADS)

    Roy, Mahendra Nath; Dakua, Vikas Kumar; Sinha, Biswajit

    2007-08-01

    Partial molar volumes (V_φ^0) and viscosity B-coefficients of sodium molybdate in 1,3-dioxolane + water mixtures have been determined from solution density and viscosity measurements at 303.15, 313.15, and 323.15 K and at various electrolyte concentrations. Also, the adiabatic compressibility of different solutions has been determined from the measurement of sound speeds at 303.15 K. The experimental density data were evaluated by the Masson equation, and the derived parameters were interpreted in terms of ion-solvent and ion-ion interactions. The viscosity data have been analyzed using the Jones-Dole equation, and the derived parameters, B and A, have also been interpreted in terms of ion-solvent and ion-ion interactions, respectively. The structure- making or breaking capacity of the electrolyte under investigation has been discussed in terms of the sign of (δ 2V_φ^0/δ T2)P . The compressibility data obtained from sound speeds of different solutions indicate the electrostriction of the solvent molecules around the ions.

  5. 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),...

  6. 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),...

  7. Infinitely dilute partial molar properties of proteins from computer simulation.

    PubMed

    Ploetz, Elizabeth A; Smith, Paul E

    2014-11-13

    A detailed understanding of temperature and pressure effects on an infinitely dilute protein's 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 method's 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.

  8. Urban aerosol refractive index prediction by partial molar refraction approach

    SciTech Connect

    Stelson, A.W. )

    1990-11-01

    The ambient aerosol of the polluted troposphere is a complex mixture of water, electrolytes, ionic solids, metal oxides and glasses, and carbonaceous material. Prediction of the refractive indexes of these inhomogeneous mixtures can be a formidable task. Contained within this paper is the necessary parameterization to estimate the mean real aerosol refractive index based on aerosol chemical composition and the partial molar refraction approach. This approach assumes all chemical constituents are homogeneously distributed throughout the aerosol phase. Consistency of the data is discussed, and this approach is verified by prediction of refractive indexes of NaOH-Si-O{sub 2}-H{sub 2}O mixtures. Finally, aerosol chemical composition data from the Los Angeles Basin are used to predict mean real aerosol refractive indexes. These values are compared to urban aerosol refractive indexes calculated via other techniques (light scattering).

  9. Reduced radiation-absorbed dose to tissues with partial panoramic radiography for evaluation of third molars.

    PubMed

    Kircos, L T; Eakle, W S; Smith, R A

    1986-05-01

    The radiation-absorbed doses from panoramic radiography, distal molar radiography, and a partial panoramic radiographic technique that exposes only the third molar region to radiation are compared. Doses of radiation to the submandibular salivary gland were comparable by all three techniques, but doses of radiation to the head and neck were reduced greatly by the partial panoramic radiographic technique. Partial panoramic radiography is a diagnostically satisfactory and a radiologically safer technique for evaluation of third molar pathosis than is panoramic or distal molar radiography. PMID:3458783

  10. Reduced radiation-absorbed dose to tissues with partial panoramic radiography for evaluation of third molars

    SciTech Connect

    Kircos, L.T.; Eakle, W.S.; Smith, R.A.

    1986-05-01

    The radiation-absorbed doses from panoramic radiography, distal molar radiography, and a partial panoramic radiographic technique that exposes only the third molar region to radiation are compared. Doses of radiation to the submandibular salivary gland were comparable by all three techniques, but doses of radiation to the head and neck were reduced greatly by the partial panoramic radiographic technique. Partial panoramic radiography is a diagnostically satisfactory and a radiologically safer technique for evaluation of third molar pathosis than is panoramic or distal molar radiography.

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

    PubMed Central

    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

  12. Densities, Excess Molar Volumes, and Thermal Expansion Coefficients of Aqueous Aminoethylethanolamine Solutions at Temperatures from 283.15 to 343.15 K.

    PubMed

    Stec, Marcin; Tatarczuk, Adam; Spiewak, Dariusz; Wilk, Andrzej

    2014-01-01

    The densities of aqueous mixtures of aminoethylethanolamine (CAS #000111-41-1) were measured over the entire compositional range at temperatures of 283.15-343.15 K. The results of these measurements were used to calculate excess molar volumes and isobaric thermal expansion coefficients, and partial molar and apparent molar volumes and excess isobaric thermal expansion coefficients were subsequently derived. The excess molar volumes were correlated as a function of the mole fraction using the Redlich-Kister equation. Temperature dependences of the Redlich-Kister coefficients are also presented. The partial molar volumes at infinite dilution of AEEA in water were determined using two different methods. In addition, the solution density was correlated using a Joubian-Acree model. Aqueous solutions of AEEA exhibit similar properties to the aqueous solutions of other alkanolamines (like monoethanolamine) used in acid gas sweetening. PMID:24899753

  13. 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.

  14. The partial molar sound speed of TiO2 in sodium silicate melts: Evidence for an exceptionally compressible component

    NASA Astrophysics Data System (ADS)

    Liu, Q.; Ai, Y.; Lange, R. A.

    2005-12-01

    Longitudinal acoustic velocities were measured at one bar by an ultrasonic frequency sweep acoustic interferometer for ten Na2O-TiO2-SiO2 (NTS) liquids for which previous density and thermal expansion measurements were made (Liu and Lange, 2001). This previous study showed that the partial molar volume of the TiO2 component varied systematically with composition and reflected changes in the average coordination of Ti4+ from values of ~4.6 to ~5.4. Sound speed data were collected at frequencies of 4.5, 5, and 6 MHz between 1233 and 1896 K; in all cases, the sound speeds decrease with increasing temperature. Six of the liquids share a similar (~25 mol%) TiO2 concentration, so that the effect of varying Na:Si ratio on the partial molar sound speed of the TiO2 component can be evaluated. The results for these ten NTS liquids were combined with sound speed data on Na2O-SiO2 liquids from the literature to derive the partial molar sound speed of the TiO2 component in these liquids. The results show that, at 1573 K, it is inversely correlated with SiO2 concentration, from values as low as 571±56 m/s to those as high as 1235±54 m/s, a variation of more than 100%. Fitted values for the partial molar sound speeds of the SiO2 and Na2O components at 1573 K are constants at 2538±52 and 2713±52 m/s, respectively. When the sound speed data are combined with density data to calculate melt compressibility, the results show that the TiO2 component is 3-15 more compressible than either the Na2O or SiO2 component. The partial molar compressibility of the TiO2 component is also strongly correlated to its partial molar thermal expansivity. It is shown that the TiO2 component is most compressible and most expansive when the average Ti4+ coordination in these sodium silicate liquids is near five, which strongly suggests that the abundance of five-coordinated Ti4+ enhances topological mechanisms of both compression and thermal expansion.

  15. Thermal diffusion and partial molar enthalpy variations of n-butane in silicalite-1.

    PubMed

    Inzoli, I; Simon, J M; Bedeaux, D; Kjelstrup, S

    2008-11-27

    We report for the first time the heat of transfer and the Soret coefficient for n-butane in silicalite-1. The heat of transfer was typically 10 kJ/mol. The Soret coefficient was typically 0.006 K(-1) at 360 K. Both varied with the temperature and the concentration. The thermal conductivity of the crystal with butane adsorbed was 1.46 +/- 0.07 W/m K. Literature values of the isosteric enthalpy of adsorption, the concentration at saturation, and the diffusion coefficients were reproduced. Nonequilibrium molecular dynamics simulations were used to find these results, and a modified heat-exchange algorithm, Soft-HEX, was developed for the purpose. Enthalpies of butane were also determined. We use these results to give numerical proof for a recently proposed relation, that the heat of transfer plus the partial molar enthalpy of butane is constant at a given temperature. The proof is offered for a regime where the partial molar enthalpy can be approximated by the molar internal energy. This result may add to the understanding of the sign of the Soret coefficient. The technical importance of the heat of transfer is discussed.

  16. 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.

  17. 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)

  18. 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.

  19. Determination of the Molar Volume of Hydrogen from the Metal-Acid Reaction: An Experimental Alternative.

    ERIC Educational Resources Information Center

    de Berg, Kevin; Chapman, Ken

    1996-01-01

    Describes an alternative technique for determining the molar volume of hydrogen from the metal-acid reaction in which the metal sample is encased in a specially prepared cage and a pipette filler is used to fill an inverted burette with water. Eliminates some difficulties encountered with the conventional technique. (JRH)

  20. 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.

  1. Strongly Composition-Dependent Partial Molar Compressibility of Water in Silicate Glasses

    NASA Astrophysics Data System (ADS)

    Whittington, A. G.; Richet, P.; Polian, A.

    2010-12-01

    Water and other volatiles have long been known to play a fundamental role in igneous processes, yet their influence on the physical properties of melts are still not well enough understood. Of particular interest is the density contrast between liquid and solid phases, which facilitates melt extraction and migration. Owing to its low molecular weight, dissolved water must decrease magma density, but the way it does so as a function of pressure remains largely to be determined. Studies on quenched melts (glasses) provide useful information because the glass has the same structure as the melt. We measured compressional and shear wave velocities of seven series of hydrous aluminosilicate glasses by Brillouin scattering at room temperature and pressure. The glasses were quenched from high temperature and 2 or 3 kbar pressure. The dry end-members range from highly polymerized albitic and granitic compositions, to depolymerized synthetic analogues of mantle-derived melts. For each set of glasses, the adiabatic shear and bulk moduli have been calculated from the measured sound velocities and densities. These moduli are linear functions of water content up to 5 wt % H2O, the highest concentration investigated, indicating that both are independent of water speciation in all series. For water-free glasses, the bulk modulus decreases from about 65 to 35 GPa with increasing degree of polymerization. Sympathetically, the partial molar bulk modulus of the water component decreases from 114 to 8 GPa, such that dissolved water amplifies the differences in rigidity between the anhydrous glasses. This strong variation indicates that the solubility mechanisms of water depend strongly on silicate composition. Depolymerized liquids are also much less compressible than their polymerized counterparts, suggesting that the partial molar compressibility of dissolved water approaches zero in depolymerized liquids. If this is correct, hydrous mantle melts formed beneath volcanic arcs would be

  2. Partial volume correction using cortical surfaces

    NASA Astrophysics Data System (ADS)

    Blaasvær, 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.

  3. Changes in molar volume and heat capacity of actin upon polymerization.

    PubMed Central

    Quirion, F; Gicquaud, C

    1993-01-01

    We have used densimetry and microcalorimetry to measure the changes in molar volume and heat capacity of the actin molecule during Mg(2+)-induced polymerization. Molar volume is decreased by 720 ml/mol. This result is in contradiction with previous measurements by Ikkai and Ooi [(1966) Science 152, 1756-1757], and by Swezey and Somero [(1985) Biochemistry 24, 852-860]: both of these groups reported increases in actin volume during polymerization, of 391 ml/mol and 63 ml/mol respectively. We also observed a decrease in heat capacity of about 69.5 kJ.K-1.mol-1 during polymerization. This is in agreement with the concept of conformational fluctuation of proteins proposed by Lumry and Gregory [(1989) J.Mol. Liq. 42, 113-144]whereby either ligand binding by a protein or monomer-monomer interaction decreases the protein's conformational flexibility. PMID:8240275

  4. Partial volume estimation using continuous representations

    NASA Astrophysics Data System (ADS)

    Siadat, Mohammad-Reza; Soltanian-Zadeh, Hamid

    2001-07-01

    This paper presents a new method for partial volume estimation using standard eigenimage method and B-splines. The proposed method is applied on the multi-parameter volumetric images such as MRI. The proposed approach uses the B-spline bases (kernels) to interpolate a continuous 2D surface or 3D density function for a sampled image dataset. It uses the Fourier domain to calculate the interpolation coefficients for each data point. Then, the above interpolation is incorporated into the standard eigenimage method. This incorporation provides a particular mask depending on the B-spline basis used. To estimate the partial volumes, this mask is convolved with the interpolation coefficients and then the eigenimage transformation is applied on the convolution result. To evaluate the method, images scanned from a 3D simulation model are used. The simulation provides images similar to CSF, white matter, and gray matter of the human brain in T1-, T2-, and PD-weighted MRI. The performance of the new method is also compared to that of the polynomial estimators.1 The results show that the new estimators have standard deviations less than that of the eigenimage method (up to 25%) and larger than those of the polynomial estimators (up to 45%). The new estimators have superior capabilities compared to that of the polynomial ones in that they provide an arbitrary degree of continuity at the boundaries of pixels/voxels. As a result, employing the new method, a continuous, smooth, and very accurate contour/surface of the desired object can be generated. The new B-spline estimators are faster than the polynomial estimators but they are slower than the standard eigenimage method.

  5. 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.

  6. Partial specific volume of poly(1-butene)

    NASA Astrophysics Data System (ADS)

    Wohlfarth, Ch.

    This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

  7. Nonlinear dependence of the solubility of water in hydrocarbons on the molar volume of the hydrocarbon

    SciTech Connect

    Ruelle, P.; Kesselring, U.W.

    1996-07-01

    The solubility of water in fifty hydrocarbon solvents at 20{degrees}C is estimated by means of the solubility equation derived from the thermodynamics of mobile order in H-bonded liquids. Neglecting the change in nonspecific cohesion forces, and assuming that water is primarily monomeric in solution, the prediction accounts for two main effects; the breaking of the H-bond network linking the water solute molecules together, and the entropy of exchange between water and solvent molecules in solution. The formation of a weak O-H ... {pi} hydrogen bond interaction is moreover taken into account according to whether the hydrocarbon is saturated or not. The overall predictive equation foresees a non-linear dependence of the water solubility on the molar volume of the hydrocarbon. Several rules are presented regarding the water solubility-hydrocarbon structure relationship.

  8. 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

  9. 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.

  10. 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.

  11. 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).

  12. Heat capacities and densities of electrolyte mixtures in aqueous solution — Application to the determination of apparent molar heat capacities and volumes for potassium triiodide and dioxoneptunium(V) perchlorate

    NASA Astrophysics Data System (ADS)

    Lemire, R. J.; Campbell, A. B.; Saluja, P. P. S.; LeBlanc, J. C.

    Apparent molar heat capacities for KI 3(aq) were determined from flow-microcalorimetric measurements of KI(aq) solutions containing dissolved iodine. From these, the conventional partial molar heat capacity C∞p,2 ( I-3, maq, 298.15 K) = 156±40 JK-1mol-1 is estimated. Also, densities and heat capacities for NpO2ClO4( aq) + HClO4( aq) mixtures were measured. Preliminary values are reported for apparent molar heat capacities (at 298.15 K) and volumes (at 296.02 K) for NpO 2ClO 4(aq). From these, values for the ionic apparent molar volume and heat capacity of NpO +2(aq) are calculated. Analysis of the data is done assuming deviations from Young's rule are small for the apparent molar heat capacities of simple electrolytes. This is shown to be true for aqueous solutions of NaCl( aq) + KBr( aq) (298.15 K and 348.15 K) and NaCl( aq) + MgCl2( aq) (348.15 K).

  13. Correction for partial volume effects in brain perfusion ECT imaging

    NASA Astrophysics Data System (ADS)

    Koole, Michel; Staelens, Steven; Van de Walle, Rik; Lemahieu, Ignace L.

    2003-05-01

    The accurate quantification of brain perfusion for emission computed tomography data (PET-SPECT) is limited by partial volume effects (PVE). This study presents a new approach to estimate accurately the true tissue tracer activity within the grey matter tissue compartment. The methodology is based on the availability of additional anatomical side information and on the assumption that activity concentration within the white matter tissue compartment is constant. Starting from an initial estimate for the white matter grey matter activity, the true tracer activity within the grey matter tissue compartment is estimated by an alternating ML-EM-algorithm. During the updating step the constant activity concentration within the white matter compartment is modelled in the forward projection in order to reconstruct the true activity distribution within the grey matter tissue compartment, hence reducing partial volume averaging. Consequently the estimate for the constant activity in the white matter tissue compartment is updated based on the new estimated activity distribution in the grey matter tissue compartment. We have tested this methodology by means of computer simulations. A T1-weighted MR brainscan of a patient was segmented into white matter, grey matter and cerebrospinal fluid, using the segmentation package of the SPM-software (Statistical Parametric Mapping). The segmented grey and white matter were used to simulate a SPECT acquisition, modelling the noise and the distance dependant detector response. Scatter and attenuation were ignored. Following the above described strategy, simulations have shown it is possible to reconstruct the true activity distribution for the grey matter tissue compartment (activity/tissue volume), assuming constant activity in the white matter tissue compartment.

  14. 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.

  15. 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 (ν̄) values are required for sedimentation velocity and sedimentation equilibrium analyses. For nucleic acids, the estimation of these values is complicated by the fact that ν̄ 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 φ′ 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 φ′, 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 φ′ with [salt] suggest that large changes in counterion association or hydration are unlikely to take place over these concentration ranges. PMID:19238377

  16. Partial volume correction in SPECT reconstruction with OSEM

    NASA Astrophysics Data System (ADS)

    Erlandsson, Kjell; Thomas, Ben; Dickson, John; Hutton, Brian F.

    2011-08-01

    SPECT images suffer from poor spatial resolution, which leads to partial volume effects due to cross-talk between different anatomical regions. By utilising high-resolution structural images (CT or MRI) it is possible to compensate for these effects. Traditional partial volume correction (PVC) methods suffer from various limitations, such as correcting a single region only, returning only regional mean values, or assuming a stationary point spread function (PSF). We recently presented a novel method in which PVC was combined with the reconstruction process in order to take into account the distance dependent PSF in SPECT, which was based on filtered backprojection (FBP) reconstruction. We now present a new method based on the iterative OSEM algorithm, which has advantageous noise properties compared to FBP. We have applied this method to a series of 10 brain SPECT studies performed on healthy volunteers using the DATSCAN tracer. T1-weighted MRI images were co-registered to the SPECT data and segmented into 33 anatomical regions. The SPECT data were reconstructed using OSEM, and PVC was applied in the projection domain at each iteration. The correction factors were calculated by forward projection of a piece-wise constant image, generated from the segmented MRI. Images were also reconstructed using FBP and standard OSEM with and without resolution recovery (RR) for comparison. The images were evaluated in terms of striatal contrast and regional variability (CoV). The mean striatal contrast obtained with OSEM, OSEM-RR and OSEM-PVC relative to FBP were 1.04, 1.42 and 1.53, respectively, and the mean striatal CoV values are 1.05, 1.53, 1.07. Both OSEM-RR and OSEM-PVC results in images with significantly higher contrast as compared to FBP or OSEM, but OSEM-PVC avoids the increased regional variability of OSEM-RR due to improved structural definition.

  17. 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 Köhler Theory Analysis (KTA) method. The molar mass of the hydrophilic and hydrophobic aerosol components is estimated to be 87±26 g mol-1 and 780±231 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.

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

    NASA Astrophysics Data System (ADS)

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

    2007-03-01

    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. For our analysis, average thermodynamic properties (i.e., molar volume) are determined for samples using our newly developed Köhler Theory Analysis (KTA) method. We have found that, the molar mass of the hydrophilic and hydrophobic aerosol components is estimated to be 87±26 g mol-1 and 780±231 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.

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

    PubMed

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

    2014-06-28

    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, α-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 volume-for 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.

  20. 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.

  1. Regional deconvolution method for partial volume correction in brain PET

    NASA Astrophysics Data System (ADS)

    Rusinek, Henry; Tsui, Wai-Hon; de Leon, Mony J.

    2001-05-01

    Correction of PET images for partial volume effects (PVE) is of particular utility in studies of metabolism in brain aging and brain disorders. PVE is commonly corrected using voxel-by- voxel factors obtained from a high resolution brain mask (obtained from the coregistered MR scan), after convolution with the point spread function (PSF) of the imaging system. In a recently proposed regional deconvolution (RD) method, the observed regional activity is expressed as linear combinations of the true metabolic activity. The weights are obtained by integrating the PSF over the geometric extent of the brain regions. We have analyzed the accuracy of RD and two other PVE correction algorithms under a variety of conditions using simulated PET scans. Each of the brain regions was assigned a distribution of metabolic activity, with gray matter/white matter contrast representative of subjects in several age categories. Simulations were performed over a wide range of PET resolutions. The influence of PET/MR misregistration and heterogeneity of brain metabolism were also evaluated. Our results demonstrate the importance of correcting PET metabolic images for PVE. Without such correction, the regional brain activity values are contaminated with 30 - 40% errors. Under most conditions studied, the accuracy of RD and of the three- compartmental method were superior to the accuracy of the two- compartmental method. Our study provides the first demonstration of the feasibility of RD algorithm to provide accurate correction for a large number (n equals 109) of brain compartments. PVE correction methods appear to be promising tools in studies of metabolism in normal brain, brain aging, and brain disorders.

  2. Effects of concentration and temperature on molar volumes of L-serine, L-isoleucine, and L-glutamine in aqueous NaCl and NaNO3 solutions

    NASA Astrophysics Data System (ADS)

    Riyazuddeen; Kumar, Dheeraj; Afrin, Sadaf

    2014-01-01

    Densities of L-serine, L-isoleucine, L-glutamine in 1.5 mol kg-1 aqueous NaCl, and NaNO3 solutions have been measured for several molal concentrations of amino acids at temperatures from 298.15 to 323.15 K. The partial molar volumes (ϕ{/v 0}) of L-serine, L-isoleucine, and L-glutamine in 1.5 mol kg-1 aqueous NaCl/NaNO3 solutions have been computed using density data. The transfer partial molar volumes (Δtrϕ{/v 0}) of L-serine, L-isoleucine, and L-glutamine from water to 1.5 mol kg-1 aqueous NaCl/1.5 mol kg-1 aqueous NaNO3 solutions have been determined at 298.15 K. The trends of variation of ϕ{/v 0} and Δtrϕ{/v 0} with change in temperature have been discussed in terms of ion-ion, ion-hydrophilic, and ion-hydrophobic interactions operative in solutions.

  3. Influence of pressure and temperature on molar volume and retention properties of peptides in ultra-high pressure liquid chromatography.

    PubMed

    Fekete, Szabolcs; Horváth, Krisztián; Guillarme, Davy

    2013-10-11

    In this study, pressure induced changes in retention were measured for model peptides possessing molecular weights between ∼1 and ∼4kDa. The goal of the present work was to evaluate if such changes were only attributed to the variation of molar volume and if they could be estimated prior to the experiments, using theoretical models. Restrictor tubing was employed to generate pressures up to 1000bar and experiments were conducted for mobile phase temperatures comprised between 30 and 80°C. As expected, the retention increases significantly with pressure, up to 200% for glucagon at around 1000bar compared to ∼100bar. The obtained data were fitted with a theoretical model and the determination coefficients were excellent (r(2)>0.9992) for the peptides at various temperatures. On the other hand, the pressure induced change in retention was found to be temperature dependent and was more pronounced at 30°C vs. 60 or 80°C. Finally, using the proposed model, it was possible to easily estimate the pressure induced increase in retention for any peptide and mobile phase temperature. This allows to easily estimating the expected change in retention, when increasing the column length under UHPLC conditions.

  4. 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, α-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 volume—for 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.

  5. 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

  6. 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.

  7. Partial US oil, gas resource volumes termed astonishing'

    SciTech Connect

    Petzet, G.A.

    1995-03-06

    Land and state waters of the US contain technically recoverable volumes of 112.6 billion bbl of oil and 1,073.8 tcf of conventional and unconventional gas, the US Geological Survey estimated. The oil figure is 44% higher than the USGS assessed in its last study, released in 1989. The assessed 715 tcf of technically recoverable conventional gas reserves, expected reserve growth, and undiscovered accumulations is nearly 42% higher than the 1989 assessment. Moreover, the USGS for the first time assessed a further 300 tcf of technically recoverable gas in continuous-type largely unconventional deposits in sandstones, shales, and chalks, and almost another 50 tcf in coal beds. USGS estimated that 60 billion bbl will be added to the oil reserves and 322 tcf to the oil reserves and 322 tcf to the gas reserves of existing fields by way of revisions, extensions, and new pool discoveries during the 80 years following 1991. The estimates assume use of existing technology, and ignore barriers to leasing of onshore federal lands. The paper describes the results more fully.

  8. Live-born diploid fetus complicated with partial molar pregnancy presenting with pre-eclampsia, maternal anemia, and seemingly huge placenta: A rare case of confined placental mosaicism and literature review.

    PubMed

    Kawasaki, Kaoru; Kondoh, Eiji; Minamiguchi, Sachiko; Matsuda, Fumihiko; Higasa, Koichiro; Fujita, Kohei; Mogami, Haruta; Chigusa, Yoshitsugu; Konishi, Ikuo

    2016-08-01

    A partial molar pregnancy almost always ends in miscarriage due to a triploid fetus. We describe a rare case of a singleton, partial molar pregnancy with a seemingly huge placenta, which continued to delivery of a live-born diploid baby. A 27-year-old primigravida suffered from severe pre-eclampsia and progressive anemia. The uterus was enormously enlarged for the gestational age. A cesarean section was performed because of deterioration of maternal status at 25 weeks' gestation, when more than 3000 mL blood spouted concurrently with the delivery of the placenta. The histological examination showed congestion in the decidua, which indicated disturbance of maternal venous return from the intervillous space. The chromosome complement of the placenta and the neonate were 69,XXX and 46,XX, respectively. We also reviewed all published cases of a singleton, partial molar pregnancy. A literature search yielded 18 cases of a singleton, diploid fetus with partial molar pregnancy. The mean gestational age at delivery was 24.5 ± 6.2 weeks, and fetuses survived outside the uterus in only four cases (22.2%). Intriguingly, previous reports numbered 10 cases with diploid placenta as well as five cases with no karyotyping of the placenta, indicating that they may have included a complete mole in a twin pregnancy or placental mesenchymal dysplasia. In conclusion, this was the first case of placentomegaly that presented manifestations of excessive abdominal distension and maternal severe anemia, and the second case of a singleton, partial molar pregnancy confirmed by chromosome analysis resulting in a diploid living baby.

  9. Live-born diploid fetus complicated with partial molar pregnancy presenting with pre-eclampsia, maternal anemia, and seemingly huge placenta: A rare case of confined placental mosaicism and literature review.

    PubMed

    Kawasaki, Kaoru; Kondoh, Eiji; Minamiguchi, Sachiko; Matsuda, Fumihiko; Higasa, Koichiro; Fujita, Kohei; Mogami, Haruta; Chigusa, Yoshitsugu; Konishi, Ikuo

    2016-08-01

    A partial molar pregnancy almost always ends in miscarriage due to a triploid fetus. We describe a rare case of a singleton, partial molar pregnancy with a seemingly huge placenta, which continued to delivery of a live-born diploid baby. A 27-year-old primigravida suffered from severe pre-eclampsia and progressive anemia. The uterus was enormously enlarged for the gestational age. A cesarean section was performed because of deterioration of maternal status at 25 weeks' gestation, when more than 3000 mL blood spouted concurrently with the delivery of the placenta. The histological examination showed congestion in the decidua, which indicated disturbance of maternal venous return from the intervillous space. The chromosome complement of the placenta and the neonate were 69,XXX and 46,XX, respectively. We also reviewed all published cases of a singleton, partial molar pregnancy. A literature search yielded 18 cases of a singleton, diploid fetus with partial molar pregnancy. The mean gestational age at delivery was 24.5 ± 6.2 weeks, and fetuses survived outside the uterus in only four cases (22.2%). Intriguingly, previous reports numbered 10 cases with diploid placenta as well as five cases with no karyotyping of the placenta, indicating that they may have included a complete mole in a twin pregnancy or placental mesenchymal dysplasia. In conclusion, this was the first case of placentomegaly that presented manifestations of excessive abdominal distension and maternal severe anemia, and the second case of a singleton, partial molar pregnancy confirmed by chromosome analysis resulting in a diploid living baby. PMID:27225660

  10. Partially erupted third molars as a potential source of infection in patients receiving peripheral stem cell transplantation for malignant diseases: a retrospective study.

    PubMed

    Ohman, David; Björk, Yvonne; Bratel, John; Kristiansson, Camilla; Johansson, Peter; Johansson, Jan-Erik; Brune, Mats; Hasséus, Bengt

    2010-02-01

    Forty-four patients with malignant diseases for which they received peripheral stem cell transplant therapy (PSCT) were retrospectively studied regarding local and systemic infection originating from around partially erupted third molars (PEMs). Twenty-two patients had one or more PEMs, while 22 patients had none. Data were retrieved from medical and dental records. Systemic and local signs of infection and treatment were assessed. We recorded the number of transplanted CD34(+) blood stem cells, days with white blood cell counts < 0.5 x 10(9) l(-1), days until engraftment, maximum level of C-reactive protein (CRP), days with fever, positive blood cultures, days taking antibiotics, days drinking < 0.5 l, days of total parenteral nutrition, days receiving intravenously administered analgesics, and number of admission days. No statistically significant difference was detected between patients with PEMs and those without PEMs regarding any of the studied parameters. Of patients with PEMs, 36% (8 of 22) developed local infections around PEMs during the PSCT period. The study indicates that PEMs pose no significant risk of causing systemic infection in patients receiving PSCT for malignant diseases but increase the risk of developing a local infection, justifying close supervision and early treatment in cases of local infection during PSCT treatment. PMID:20156265

  11. 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.

  12. Fitting parametric models of diffusion MRI in regions of partial volume

    NASA Astrophysics Data System (ADS)

    Eaton-Rosen, Zach; Cardoso, M. J.; Melbourne, Andrew; Orasanu, Eliza; Bainbridge, Alan; Kendall, Giles S.; Robertson, Nicola J.; Marlow, Neil; Ourselin, Sebastien

    2016-03-01

    Regional analysis is normally done by fitting models per voxel and then averaging over a region, accounting for partial volume (PV) only to some degree. In thin, folded regions such as the cerebral cortex, such methods do not work well, as the partial volume confounds parameter estimation. Instead, we propose to fit the models per region directly with explicit PV modeling. In this work we robustly estimate region-wise parameters whilst explicitly accounting for partial volume effects. We use a high-resolution segmentation from a T1 scan to assign each voxel in the diffusion image a probabilistic membership to each of k tissue classes. We rotate the DW signal at each voxel so that it aligns with the z-axis, then model the signal at each voxel as a linear superposition of a representative signal from each of the k tissue types. Fitting involves optimising these representative signals to best match the data, given the known probabilities of belonging to each tissue type that we obtained from the segmentation. We demonstrate this method improves parameter estimation in digital phantoms for the diffusion tensor (DT) and `Neurite Orientation Dispersion and Density Imaging' (NODDI) models. The method provides accurate parameter estimates even in regions where the normal approach fails completely, for example where partial volume is present in every voxel. Finally, we apply this model to brain data from preterm infants, where the thin, convoluted, maturing cortex necessitates such an approach.

  13. 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)

  14. 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

  15. Quantitative Magnetic Resonance Imaging Detects Changes in Meniscal Volume in Vivo After Partial Meniscectomy

    PubMed Central

    Bowers, Megan E.; Tung, Glenn A.; Oksendahl, Heidi L.; Hulstyn, Michael J.; Fadale, Paul D.; Machan, Jason T.; Fleming, Braden C.

    2010-01-01

    Background Quantifying changes in meniscal volume in vivo before and after partial meniscectomy (PM) could help elucidate the mechanisms involved in osteoarthritis development after meniscal injury and its surgical treatment. Purpose/Hypothesis To determine whether quantitative MRI (qMRI) could detect the immediate reduction in meniscal volume created by PM, while ruling out changes in unresected structures. We hypothesized that qMRI would be reliable for determining meniscal volume within the repeated images of unresected menisci. Additionally, we expected no significant difference in volume between the uninjured menisci of the injured knees and the same menisci of the uninjured knees. Study Design Controlled laboratory study. Methods Ten subjects with meniscal tears were evaluated with 3T MRI before and after arthroscopic PM. Manual segmentation was used to create models of the menisci and to determine the pre- and post-operative meniscal volumes for each subject. The responsiveness and reliability of qMRI for determining meniscal volume in vivo were evaluated using these measurements. We expected a decrease in volume of the resected menisci, but not in the uninjured menisci, after surgery. Results The mean pre-operative volume of the injured menisci was significantly greater than the mean post-operative volume (2896±277mm3 vs. 2480±277mm3; p=0.000). There was no significant difference between the mean pre- and post-operative volumes of the uninjured menisci (2687±256mm3 vs. 2694±256mm3; p=1.000). Conclusions Manual segmentation demonstrated a significant reduction in the volume of the surgically resected menisci after PM, but no significant change in the volume of unresected meniscal tissue, indicating that the manual segmentation method is responsive. Clinical Relevance This approach offers a novel, reliable method to study the relationship between the volume of meniscal tissue removed during PM and subsequent patient outcomes during long-term clinical

  16. Three-dimensional bone microstructures of the mandibular angle using micro-CT and finite element analysis: relationship between partially impacted mandibular third molars and angle fractures.

    PubMed

    Takada, Hideki; Abe, Shinichi; Tamatsu, Yuichi; Mitarashi, Satoshi; Saka, Hideki; Ide, Yoshinobu

    2006-02-01

    The mandibular angle is one of the areas of the mandible that are prone to bone fractures, and the presence of an impacted third molar has been found to be associated with increased risk of angle fractures. The factors involved in bone fractures are the amount and direction of load, and the biomechanical and anatomical properties of bone. In the present study, micro-focused X-ray computed tomography was performed to observe and analyze the three-dimensional (3D) bone microstructure of the mandibular angle, and finite element analysis was conducted to examine the relationship between angle fractures and the presence or absence of mandibular third molars. 3D bone microstructure showed no marked difference between mandibles with and without third molars. Finite element analysis showed that, in the mandible with a third molar, stress was concentrated around the root apex of the third molar, and was transmitted in a direction matching the clinical findings of angle fractures. The results obtained in this study suggest that the presence of an impacted third molar changes the concentration and transmission of stress in the mandible, thus increasing the risk of an angle fracture.

  17. Composition et volume molaire apparent des gels Ca_Si, une approche expérimentaleComposition and apparent molar volume of Ca_Si gels, an experimental approach

    NASA Astrophysics Data System (ADS)

    Perruchot, Alain; Massard, Pierre; Lombardi, Jérôme

    2003-11-01

    Synthetic CaSi gels of various compositions were prepared from sodium metasilicate and calcium chloride solutions. These synthetic CaSi gels are good analogues of fresh natural gels found within concrete affected by Alkalis-Silica Reaction (ASR). Results show that these synthetic gels in equilibrium with their formation solutions present an optimum of composition for a molar ratio CaO/SiO 2=(C/S) g≅0.48. Correspondingly, this characteristic value of (C/S) g denotes a rearrangement in the structure of gels accounted for the variation with (C/S) g of the apparent molar volume Vg. To cite this article: A. Perruchot et al., C. R. Geoscience 335 (2003).

  18. Reduction of thioredoxin significantly decreases its partial specific volume and adiabatic compressibility.

    PubMed Central

    Kaminsky, S. M.; Richards, F. M.

    1992-01-01

    The partial specific volume and adiabatic compressibility were determined at several temperatures for oxidized and reduced Escherichia coli thioredoxin. Oxidized thioredoxin had a partial specific volume of 0.785-0.809 mL/g at the observed upper limit for all proteins whereas the partial specific volume of reduced thioredoxin was 0.745-0.755 mL/g, a value in the range found for a majority of proteins. The adiabatic compressibility of oxidized thioredoxin was also much larger (9.8-18 x 10(-12) cm2 dyne-1) than that of the reduced protein (3.8-7.3 x 10(-12)). Apart from the region immediately around the small disulfide loop, the structures of the oxidized (X-ray, crystal) and reduced protein (nuclear magnetic resonance, solution) are reported to be very similar. It would appear that alterations in the solvent layer in contact with the protein surface must play a major role in producing these large changes in the apparent specific volumes and compressibilities in this system. Some activities of thioredoxin require the reduced structure but are not electron transfer reactions. The large changes in physical parameters reported here suggest the possibility of a reversible metabolic control function for the SS bond. PMID:1304879

  19. Partial volume segmentation in 3D of lesions and tissues in magnetic resonance images

    NASA Astrophysics Data System (ADS)

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

    1994-05-01

    An important first step in diagnosis and treatment planning using tomographic imaging is differentiating and quantifying diseased as well as healthy tissue. One of the difficulties encountered in solving this problem to date has been distinguishing the partial volume constituents of each voxel in the image volume. Most proposed solutions to this problem involve analysis of planar images, in sequence, in two dimensions only. We have extended a model-based method of image segmentation which applies the technique of iterated conditional modes in three dimensions. A minimum of user intervention is required to train the algorithm. Partial volume estimates for each voxel in the image are obtained yielding fractional compositions of multiple tissue types for individual voxels. A multispectral approach is applied, where spatially registered data sets are available. The algorithm is simple and has been parallelized using a dataflow programming environment to reduce the computational burden. The algorithm has been used to segment dual echo MRI data sets of multiple sclerosis patients using lesions, gray matter, white matter, and cerebrospinal fluid as the partial volume constituents. The results of the application of the algorithm to these datasets is presented and compared to the manual lesion segmentation of the same data.

  20. Computerized MRS voxel registration and partial volume effects in single voxel 1H-MRS.

    PubMed

    Lee, Hedok; Caparelli, Elisabeth; Li, Haifang; Mandal, Amit; Smith, S David; Zhang, Shaonan; Bilfinger, Thomas V; Benveniste, Helene

    2013-09-01

    Partial volume effects in proton magnetic resonance spectroscopy in the brain have been studied previously in terms of proper water concentration calculations, but there is a lack of disclosure in terms of voxel placement techniques that would affect the calculations. The purpose of this study is to facilitate a fully automated MRS voxel registration method which is time efficient, accurate, and can be extended to all imaging modalities. A total of thirteen healthy adults underwent single voxel 1H-MRS scans in 3.0T MRI scanners. Transposition of a MRS voxel onto an anatomical scan is derived along with a full calculation of water concentration with a correction term to account for the partial volume effects. Five metabolites (tNAA, Glx, tCr, mI, and tCho) known to yield high reliability are studied. Pearson's correlation analyses between tissue volume fractions and metabolite concentrations were statistically significant in parietal (tCr, Glx, and tNAA) lobe and occipital lobe (tNAA). MRS voxel overlaps quantified by dice metric over repeated visits yielded 60%~70% and coefficients of variance in metabolites concentration were 4%~10%. These findings reiterate an importance of considering the partial volume effects when tissue water is used as an internal concentration reference so as to avoid misinterpreting a morphometric difference as a metabolic difference.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Apparent molar volumes and apparent molar heat capacities of Pr(NO3)3(aq), Gd(NO3)3(aq), Ho(NO3)3(aq), and Y(NO3)3(aq) at T = (288.15, 298.15, 313.15 and 328.15) K and p = 0.1 MPa

    SciTech Connect

    Rard, J; Lui, J; Erickson, K; Munoz, J; Hakin, A H

    2004-07-13

    Relative densities and relative massic heat capacities have been measured for acidified solutions (prepared at University of Lethbridge) of Y(NO{sub 3}){sub 3}(aq), Pr(NO{sub 3}){sub 3}(aq), and Gd(NO{sub 3}){sub 3}(aq) at T = (288.15, 298.15, 313.15, and 328.15) K and p = 0.1 MPa. In addition, relative densities and massic heat capacities have been measured at the same temperatures and pressure for Y(NO{sub 3}){sub 3}(aq) and Ho(NO{sub 3}){sub 3}(aq) solutions which were supplied from the Lawrence Livermore National Laboratory (LLNL) (n.b. measurements at T = 328.15 K for Ho(NO{sub 3}){sub 3}(aq) were not performed due to the limited volume of solution available). Apparent molar volumes and apparent molar heat capacities for the aqueous salt solutions have been calculated from the experimental apparent molar properties of the acidified salt solutions using Young's Rule whereas the apparent molar properties of the LLNL solutions were calculated directly from the measured densities and massic heat capacities. The two sets of data for the Y(NO{sub 3}){sub 3}(aq) systems provide a check of the internal consistency of the Young's Rule approach we have utilized. The concentration dependences of the apparent molar volumes and heat capacities of the aqueous salt solutions have been modeled at each investigated temperature using the Pitzer ion interaction equations to yield apparent molar properties at infinite dilution. Complex formation within the aqueous rare earth nitrate systems is discussed and is qualitatively explored by probing the concentration dependence of apparent molar volumes and heat capacities. It is also shown that in spite of the complex formation within the aqueous rare earth nitrate systems there remains a high degree of self-consistency between the apparent molar volumes and heat capacities at infinite dilution reported in this manuscript and those previously reported for aqueous rare earth perchlorate salt systems.

  7. Hitchhiker’s Guide to Voxel Segmentation for Partial Volume Correction of In Vivo Magnetic Resonance Spectroscopy

    PubMed Central

    Quadrelli, Scott; Mountford, Carolyn; Ramadan, Saadallah

    2016-01-01

    Partial volume effects have the potential to cause inaccuracies when quantifying metabolites using proton magnetic resonance spectroscopy (MRS). In order to correct for cerebrospinal fluid content, a spectroscopic voxel needs to be segmented according to different tissue contents. This article aims to detail how automated partial volume segmentation can be undertaken and provides a software framework for researchers to develop their own tools. While many studies have detailed the impact of partial volume correction on proton magnetic resonance spectroscopy quantification, there is a paucity of literature explaining how voxel segmentation can be achieved using freely available neuroimaging packages. PMID:27147822

  8. Alzheimer's disease detection using 11C-PiB with improved partial volume effect correction

    NASA Astrophysics Data System (ADS)

    Raniga, Parnesh; Bourgeat, Pierrick; Fripp, Jurgen; Acosta, Oscar; Ourselin, Sebastien; Rowe, Christopher; Villemagne, Victor L.; Salvado, Olivier

    2009-02-01

    Despite the increasing use of 11C-PiB in research into Alzheimer's disease (AD), there are few standardized analysis procedures that have been reported or published. This is especially true with regards to partial volume effects (PVE) and partial volume correction. Due to the nature of PET physics and acquisition, PET images exhibit relatively low spatial resolution compared to other modalities, resulting in bias of quantitative results. Although previous studies have applied PVE correction techniques on 11C-PiB data, the results have not been quantitatively evaluated and compared against uncorrected data. The aim of this study is threefold. Firstly, a realistic synthetic phantom was created to quantify PVE. Secondly, MRI partial volume estimate segmentations were used to improve voxel-based PVE correction instead of using hard segmentations. Thirdly, quantification of PVE correction was evaluated on 34 subjects (AD=10, Normal Controls (NC)=24), including 12 PiB positive NC. Regional analysis was performed using the Anatomical Automatic Labeling (AAL) template, which was registered to each patient. Regions of interest were restricted to the gray matter (GM) defined by the MR segmentation. Average normalized intensity of the neocortex and selected regions were used to evaluate the discrimination power between AD and NC both with and without PVE correction. Receiver Operating Characteristic (ROC) curves were computed for the binary discrimination task. The phantom study revealed signal losses due to PVE between 10 to 40 % which were mostly recovered to within 5% after correction. Better classification was achieved after PVE correction, resulting in higher areas under ROC curves.

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

    PubMed

    Lévy, 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

  10. 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

  11. A unifying framework for partial volume segmentation of brain MR images.

    PubMed

    Van Leemput, Koen; Maes, Frederik; Vandermeulen, Dirk; Suetens, Paul

    2003-01-01

    Accurate brain tissue segmentation by intensity-based voxel classification of magnetic resonance (MR) images is complicated by partial volume (PV) voxels that contain a mixture of two or more tissue types. In this paper, we present a statistical framework for PV segmentation that encompasses and extends existing techniques. We start from a commonly used parametric statistical image model in which each voxel belongs to one single tissue type, and introduce an additional downsampling step that causes partial voluming along the borders between tissues. An expectation-maximization approach is used to simultaneously estimate the parameters of the resulting model and perform a PV classification. We present results on well-chosen simulated images and on real MR images of the brain, and demonstrate that the use of appropriate spatial prior knowledge not only improves the classifications, but is often indispensable for robust parameter estimation as well. We conclude that general robust PV segmentation of MR brain images requires statistical models that describe the spatial distribution of brain tissues more accurately than currently available models.

  12. Partial volume correction using structural-functional synergistic resolution recovery: comparison with geometric transfer matrix method.

    PubMed

    Kim, Euitae; Shidahara, Miho; Tsoumpas, Charalampos; McGinnity, Colm J; Kwon, Jun Soo; Howes, Oliver D; Turkheimer, Federico E

    2013-06-01

    We validated the use of a novel image-based method for partial volume correction (PVC), structural-functional synergistic resolution recovery (SFS-RR) for the accurate quantification of dopamine synthesis capacity measured using [(18)F]DOPA positron emission tomography. The bias and reliability of SFS-RR were compared with the geometric transfer matrix (GTM) method. Both methodologies were applied to the parametric maps of [(18)F]DOPA utilization rates (ki(cer)). Validation was first performed by measuring repeatability on test-retest scans. The precision of the methodologies instead was quantified using simulated [(18)F]DOPA images. The sensitivity to the misspecification of the full-width-half-maximum (FWHM) of the scanner point-spread-function on both approaches was also assessed. In the in-vivo data, the ki(cer) was significantly increased by application of both PVC procedures while the reliability remained high (intraclass correlation coefficients >0.85). The variability was not significantly affected by either PVC approach (<10% variability in both cases). The corrected ki(cer) was significantly influenced by the FWHM applied in both the acquired and simulated data. This study shows that SFS-RR can effectively correct for partial volume effects to a comparable degree to GTM but with the added advantage that it enables voxelwise analyses, and that the FWHM used can affect the PVC result indicating the importance of accurately calibrating the FWHM used in the recovery model.

  13. 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

  14. Comparison of Partial Volume Effects in Arterial and Venous Contrast Curves in CT Brain Perfusion Imaging

    PubMed Central

    Riordan, Alan J.; Bennink, Edwin; Dankbaar, Jan Willem; Viergever, Max A.; Velthuis, Birgitta K.; Smit, Ewoud J.; de Jong, Hugo W. A. M.

    2014-01-01

    Purpose In brain CT perfusion (CTP), the arterial contrast bolus is scaled to have the same area under the curve (AUC) as the venous outflow to correct for partial volume effects (PVE). This scaling is based on the assumption that large veins are unaffected by PVE. Measurement of the internal carotid artery (ICA), usually unaffected by PVE due to its large diameter, may avoid the need for partial volume correction. The aims of this work are to examine i) the assumptions behind PVE correction and ii) the potential of selecting the ICA obviating correction for PVE. Methods The AUC of the ICA and sagittal sinus were measured in CTP datasets from 52 patients. The AUCs were determined by i) using commercial CTP software based on a Gaussian curve-fitting to the time attenuation curve, and ii) by simple integration of the time attenuation curve over a time interval. In addition, frames acquired up to 3 minutes after first bolus passage were used to examine the ratio of arterial and venous enhancement. The impact of selecting the ICA without PVE correction was illustrated by reporting cerebral blood volume (CBV) measurements. Results In 49 of 52 patients, the AUC of the ICA was significantly larger than that of the sagittal sinus (p = 0.017). Measured after the first pass bolus, contrast enhancement remained 50% higher in the ICA just after the first pass bolus, and 30% higher 3 minutes later. CBV measurements were significantly lowered when the ICA was used without PVE correction. Conclusions Contradicting the assumptions underlying PVE correction, contrast in the ICA was significantly higher than in the sagittal sinus, even 3 minutes after the first pass of the contrast bolus. PVE correction might lead to overestimation of CBV if the CBV is calculated using the AUC of the time attenuation curves. PMID:24858308

  15. Object strength--an accurate measure for small objects that is insensitive to partial volume effects.

    PubMed

    Tofts, P S; Silver, N C; Barker, G J; Gass, A

    2005-07-01

    There are currently four problems in characterising small nonuniform lesions or other objects in Magnetic Resonance images where partial volume effects are significant. Object size is over- or under-estimated; boundaries are often not reproducible; mean object value cannot be measured; and fuzzy borders cannot be accommodated. A new measure, Object Strength, is proposed. This is the sum of all abnormal intensities, above a uniform background value. For a uniform object, this is simply the product of the increase in intensity and the size of the object. Biologically, this could be at least as relevant as existing measures of size or mean intensity. We hypothesise that Object Strength will perform better than traditional area measurements in characterising small objects. In a pilot study, the reproducibility of object strength measurements was investigated using MR images of small multiple sclerosis (MS) lesions. In addition, accuracy was investigated using artificial lesions of known volume (0.3-6.2 ml) and realistic appearance. Reproducibility approached that of area measurements (in 33/90 lesion reports the difference between repeats was less than for area measurements). Total lesion volume was accurate to 0.2%. In conclusion, Object Strength has potential for improved characterisation of small lesions and objects in imaging and possibly spectroscopy.

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

    PubMed

    Ahlgren, André; Wirestam, Ronnie; Petersen, Esben Thade; Ståhlberg, 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

  17. Partial volume effect of cingulum tract in diffusion-tensor MRI

    NASA Astrophysics Data System (ADS)

    Cao, Ning; Gold, Brian T.; Zhang, Jun

    2008-03-01

    Diffusion tensor imaging (DTI) represents a promising tool for the early diagnosis of certain brain diseases. Many DTI studies have compared differences in local diffusivity in specific region-of- interest (ROI) between patient and control groups to find possible disease markers. However, local diffusivity results may be influenced by partial volume effects (PVE), particularly in small white matter tracts that border grey matter tissue. Here, we investigated the influence of PVE on local diffusivity measurements in a small but critical white matter tract, the cingulum. Results demonstrated significant variability in PVE that contribute to local diffusivity in the cingulum. Our results highlight the need for careful consideration of PVE when computing diffusivity of small tissues.

  18. A modified probabilistic neural network for partial volume segmentation in brain MR image.

    PubMed

    Song, Tao; Jamshidi, Mo M; Lee, Roland R; Huang, Mingxiong

    2007-09-01

    A modified probabilistic neural network (PNN) for brain tissue segmentation with magnetic resonance imaging (MRI) is proposed. In this approach, covariance matrices are used to replace the singular smoothing factor in the PNN's kernel function, and weighting factors are added in the pattern of summation layer. This weighted probabilistic neural network (WPNN) classifier can account for partial volume effects, which exist commonly in MRI, not only in the final result stage, but also in the modeling process. It adopts the self-organizing map (SOM) neural network to overly segment the input MR image, and yield reference vectors necessary for probabilistic density function (pdf) estimation. A supervised "soft" labeling mechanism based on Bayesian rule is developed, so that weighting factors can be generated along with corresponding SOM reference vectors. Tissue classification results from various algorithms are compared, and the effectiveness and robustness of the proposed approach are demonstrated. PMID:18220190

  19. 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.

  20. 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}.

  1. 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

  2. Anatomical-based Partial Volume Correction for Low-dose Dedicated Cardiac SPECT/CT

    PubMed Central

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

    2016-01-01

    Due to the limited spatial resolution, partial volume effect (PVE) 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 (FOV) 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

  3. 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

  4. 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

  5. Multicomponent T2 Analysis of Articular Cartilage With Synovial Fluid Partial Volume Correction

    PubMed Central

    Liu, Fang; Chaudhary, Rajeev; Block, Walter F.; Samsonov, Alexey; Kijowski, Richard

    2016-01-01

    Purpose To investigate the use of a three-pool model to account for the confounding effects of synovial fluid on multicomponent T2 analysis of articular cartilage using Multicomponent Driven Equilibrium Single Shot Observation of T1 and T2 (mcDESPOT). Materials and Methods mcDESPOT was performed on the knee of eight asymptomatic volunteers and eight patients with osteoarthritis at 3.0T with multicomponent T2 maps created using the two-pool model and a three-pool model containing a nonexchanging synovial fluid water pool. The fraction of the fast-relaxing water component (FF) and the T2 relaxation times for the fast-relaxing (T2F) and slow-relaxing (T2S) water components were measured in the superficial and deep layers of patellar cartilage using the two-pool and three-pool models in asymptomatic volunteers and patients with osteoarthritis and were compared using Wilcoxon signed rank tests. Results Within the superficial layer of patellar cartilage, FF was 22.5% and 25.6% for asymptomatic volunteers and 21.3% and 22.8% for patients with osteoarthritis when using the two-pool and three-pool models, respectively, while T2S was 73.9 msec and 62.0 msec for asymptomatic volunteers and 72.0 msec and 63.1 msec for patients with osteoarthritis when using the two-pool and three-pool models, respectively. For both asymptomatic volunteers and patients with osteoarthritis, the two-pool model provided significantly (P < 0.05) lower FF and higher T2S than the three-pool model, likely due to the effects of synovial fluid partial volume averaging. Conclusion The effects of partial volume averaging between superficial cartilage and synovial fluid may result in biased multicomponent T2 measurements that can be corrected using an mcDESPOT three-pool model containing a nonexchanging synovial fluid water pool. PMID:26435385

  6. 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 β-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 β-human chorionic gonadotropin level has remained consistently below detectable levels.

  7. The system H 2O-NaCl. Part II: Correlations for molar volume, enthalpy, and isobaric heat capacity from 0 to 1000 °C, 1 to 5000 bar, and 0 to 1 XNaCl

    NASA Astrophysics Data System (ADS)

    Driesner, Thomas

    2007-10-01

    A set of correlations for the volumetric properties and enthalpies of phases in the system H 2O-NaCl as a function of temperature, pressure, and composition has been developed that yields accurate values from 0 to 1000 °C, 1 to 5000 bar, and 0 to 1 XNaCl. The volumetric properties of all fluid phases from low-density vapor to hydrous salt melts and single-phase binary fluids at high pressures and temperatures, can be described by a simple equation V(T,P,X)=VO(n1+n2T,P) i.e., for a given pressure and composition, the molar volume of the solution is related to the molar volume of pure water at the same pressure by a linear scaling of temperature. The parameters n1 and n2 are simple functions of pressure and composition. This linear relation could be demonstrated for all ( P, XNaCl) pairs where accurate volumetric data are available over a sufficiently large temperature interval. Extrapolations over as much as 300 °C predict high temperature data within their experimental uncertainty of 1-2%. With a simple fit of parameters n1 and n2, the vast majority of several thousand experimental data points from the literature can be reproduced within experimental error, including dilute solutions in the compressible region. Although a strict theoretical foundation is lacking, this behavior can phenomenologically be rationalized as reflecting the relation between the linear to near-linear isochores of binary fluids to those of pure water. Accordingly, small deviations from linearity that amount to 0.1-0.2% error in molar volume occur only at low temperatures where the pure water isochores behave non-linearly. This effect is accounted for by introducing a deviation function. Given its high accuracy, the formulation for the molar volumes could be integrated along isotherms-isobars to generate data for the specific enthalpy of binary solutions. In order to allow direct computation rather than numerical integration, a correlation scheme was developed that is mathematically similar

  8. Isotropic non-white matter partial volume effects in constrained spherical deconvolution.

    PubMed

    Roine, Timo; Jeurissen, Ben; Perrone, Daniele; Aelterman, Jan; Leemans, Alexander; Philips, Wilfried; Sijbers, Jan

    2014-01-01

    Diffusion-weighted (DW) magnetic resonance imaging (MRI) is a non-invasive imaging method, which can be used to investigate neural tracts in the white matter (WM) of the brain. Significant partial volume effects (PVEs) are present in the DW signal due to relatively large voxel sizes. These PVEs can be caused by both non-WM tissue, such as gray matter (GM) and cerebrospinal fluid (CSF), and by multiple non-parallel WM fiber populations. High angular resolution diffusion imaging (HARDI) methods have been developed to correctly characterize complex WM fiber configurations, but to date, many of the HARDI methods do not account for non-WM PVEs. In this work, we investigated the isotropic PVEs caused by non-WM tissue in WM voxels on fiber orientations extracted with constrained spherical deconvolution (CSD). Experiments were performed on simulated and real DW-MRI data. In particular, simulations were performed to demonstrate the effects of varying the diffusion weightings, signal-to-noise ratios (SNRs), fiber configurations, and tissue fractions. Our results show that the presence of non-WM tissue signal causes a decrease in the precision of the detected fiber orientations and an increase in the detection of false peaks in CSD. We estimated 35-50% of WM voxels to be affected by non-WM PVEs. For HARDI sequences, which typically have a relatively high degree of diffusion weighting, these adverse effects are most pronounced in voxels with GM PVEs. The non-WM PVEs become severe with 50% GM volume for maximum spherical harmonics orders of 8 and below, and already with 25% GM volume for higher orders. In addition, a low diffusion weighting or SNR increases the effects. The non-WM PVEs may cause problems in connectomics, where reliable fiber tracking at the WM-GM interface is especially important. We suggest acquiring data with high diffusion-weighting 2500-3000 s/mm(2), reasonable SNR (~30) and using lower SH orders in GM contaminated regions to minimize the non-WM PVEs in CSD

  9. 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.

  10. Two methods to generate templates for template-based partial volume effect correction: SPECT phantom experiments.

    PubMed

    Shcherbinin, S; Grimes, J; Celler, A

    2013-02-21

    In this paper, we explore the applicability of template-based compensation for the partial volume effect (PVE) for situations where (i) the image has multiple uptake sites (tumors and organs) but only one of them is treated as a region of interest (ROI) with the boundaries available from a high-resolution modality and (ii) no information regarding activities inside or outside this ROI is a priori available. We modeled this situation by performing SPECT acquisitions of phantoms containing 21 containers, which had different shapes and sizes and were filled with different levels of activity. In our analysis, each of these containers was treated as an individual ROI. We compared the performance of two methods of template construction. In method 1, the ROI template value was obtained from a conventionally reconstructed (without PVEC) image. In method 2, the ROI template value was directly (bypassing the PVE-affected conventional image) calculated from projections using region-based reconstruction. Our processing shows that method 1 resulted in consistent (activities for all 21 ROIs were improved) but relatively weak PVE compensation (errors of recovered total activities were equal to or lower than 10% for 5 ROIs only). Application of method 2 resulted in a selective (activities for 19 ROIs were improved) but considerably better compensation when compared to method 1 (errors of recovered total activities were equal to or lower than 10% for 10 ROIs).

  11. 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

  12. Effects of concentration, temperature and solvent composition on density and apparent molar volume of the binary mixtures of cationic-anionic surfactants in methanol-water mixed solvent media.

    PubMed

    Bhattarai, Ajaya; Chatterjee, Sujeet Kumar; Niraula, Tulasi Prasad

    2013-01-01

    The accurate measurements on density of the binary mixtures of cetyltrimethylammonium bromide and sodium dodecyl sulphate in pure water and in methanol(1) + water (2) mixed solvent media containing (0.10, 0.20, and 0.30) volume fractions of methanol at 308.15, 318.15, and 323.15 K are reported. The concentrations are varied from (0.03 to 0.12) mol.l(-1) of sodium dodecyl sulphate in presence of ~ 5.0×10(-4) mol.l(-1) cetyltrimethylammonium bromide. The results showed almost increase in the densities with increasing surfactant mixture concentration, also the densities are found to decrease with increasing temperature over the entire concentration range, investigated in a given mixed solvent medium and these values are found to decrease with increasing methanol content in the solvent composition. The concentration dependence of the apparent molar volumes appear to be negligible over the entire concentration range, investigated in a given mixed solvent medium and the apparent molar volumes increase with increasing temperature and are found to decrease with increasing methanol content in the solvent composition.

  13. An interpretative model for the anomalous behavior of some excess properties in mixed liquid systems: A relationship between excess molar volumes and excess compressibilities in strongly self-aggregated fluids

    NASA Astrophysics Data System (ADS)

    Raudino, Antonio; Palombo, Francesca; Cataliotti, Rosario Sergio

    2008-07-01

    A simple theoretical model based on the hole theory of the liquid state has been developed in order to find a relationship between the excess molar volume and the excess compressibility of a two-component fluid. The model has been extended to investigate strongly associating fluids dissolved in an apolar solvent. Such a model nicely explains our recent results obtained from a Brillouin scattering study of the nonideal mixture between tert-butyl alcohol and 2-2' dimethyl butane. Its validity, however, seems to be rather general and it could be usefully applied to rationalize the excess properties of several nonideal binary fluid mixtures.

  14. 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, Irène

    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 0.7±9.7% without PVC and was -8.5±14.5% with PVC, suggesting that the simulated data reproduced the real data well enough. For the simulated patients, BP was underestimated by 66.6±9.3% on average without PVC and overestimated by 11.3±9.5% 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

  15. Diminishing the impact of the partial volume effect in cardiac SPECT perfusion imaging.

    PubMed

    Pretorius, P Hendrik; King, Michael A

    2009-01-01

    The partial volume effect (PVE) significantly restricts the absolute quantification of regional myocardial uptake and thereby limits the accuracy of absolute measurement of blood flow and coronary flow reserve by SPECT. The template-projection-reconstruction method has been previously developed for PVE compensation. This method assumes the availability of coregistered high-spatial resolution anatomical information as is now becoming available with commercial dual-modality imaging systems such as SPECT/CTs. The objective of this investigation was to determine the extent to which the impact of the PVE on cardiac perfusion SPECT imaging can be diminished if coregistered high-spatial resolution anatomical information is available. For this investigation the authors introduced an additional parameter into the template-projection-reconstruction compensation equation called the voxel filling fraction (F). This parameter specifies the extent to which structure edge voxels in the emission reconstruction are filled by the structure in question as determined by the higher spatial-resolution imaging modality and the fractional presence of the structure at different states of physiological motion as in combining phases of cardiac motion. During correction the removal of spillover to the cardiac region from the surrounding structures is performed first by using reconstructed templates of neighboring structures (liver, blood pool, lungs) to calculate spillover fractions. This is followed by determining recovery coefficients for all voxels within the heart wall from the reconstruction of the template projections of the left and right ventricles (LV and RV). The emission data are subsequently divided by these recovery coefficients taking into account the filling fraction F. The mathematical cardiac torso phantom was used for investigation correction of PVE for a normal LV distribution, a defect in the inferior wall, and a defect in the anterior wall. PVE correction resulted in a

  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

  17. The studies of density, apparent molar volume, and viscosity of bovine serum albumin, egg albumin, and lysozyme in aqueous and RbI, CsI, and DTAB aqueous solutions at 303.15 K.

    PubMed

    Singh, Man; Chand, Hema; Gupta, K C

    2005-06-01

    Density (rho), apparent molar volume (V(phi)), and viscosity (eta) of 0.0010 to 0.0018% (w/v) of bovine serum albumin (BSA), egg albumin, and lysozyme in 0.0002, 0.0004, and 0.0008 M aqueous RbI and CsI, and (dodecyl)(trimethyl)ammonium bromide (DTAB) solutions were obtained. The experimental data were regressed against composition, and constants are used to elucidate the conformational changes in protein molecules. With salt concentration, the density of proteins is found to decrease, and the order of the effect of additives on density is observed as CsI > RbI > DTAB. The trend of apparent molar volume of proteins is found as BSA > egg-albumin > lysozyme for three additives. In general, eta values of BSA remain higher for all compositions of RbI than that of egg-albumin for CsI and DTAB. These orders of the data indicate the strength of intermolecular forces between proteins and salts, and are helpful for understanding the denaturation of proteins.

  18. Blood volume responses in partially dehydrated subjects working in the cold.

    PubMed

    Tappan, D V; Jacey, M J; Heyder, E; Gray, P H

    1984-04-01

    The effects of high-salt diets, cold, and heavy exercise have been examined in 33 Marine Corps volunteers living and working in a cold chamber. Temperatures varied from -29 degrees C during working hours to -4 degrees C, simulating partly warmed shelters, at night. Dehydrated operational rations were eaten and fluid intakes were controlled. When quantities of water were consumed at or above the amounts determined in previous studies in this series to prevent symptoms of cold-induced dehydration with these diets, ie., 2.5-3.0 L/d with diets containing 24 g of NaCl/d or about 2.0 L/d with 8 g NaCl/d, blood volumes increased 5-10%, primarily as a result of plasma volume expansion. This finding apparently confirms the results of earlier workers who have noted plasma volume increases in subjects undergoing vigorous exercise training. In subjects receiving 0.5 L/d or more below recommended quantities of water, intravascular volume increases developed slowly and quite erratically during 5 d of exercise. Intravascular volume increases responded within 1-2 d when fluid levels became appropriate for either high- or low-salt intakes. Besides confirming recommendations concerning water needed with dehydrated diets under conditions of the experiment, the observation of intravascular fluid volume increases during exercise training--despite limiting fluid intakes--raises the question of whether there are any physiological advantages from this adaptive mechanism.

  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. Transfer Partial Molar Isentropic Compressibilities of ( l-Alanine/ l-Glutamine/Glycylglycine) from Water to 0.512 {mol} \\cdot {kg}^{-1} Aqueous {KNO}3/0.512 {mol} \\cdot {kg}^{-1} Aqueous {K}2{SO}4 Solutions Between 298.15 K and 323.15 K

    NASA Astrophysics Data System (ADS)

    Riyazuddeen; Gazal, Umaima

    2013-03-01

    Speeds of sound of ( l-alanine/ l-glutamine/glycylglycine + 0.512 {mol}\\cdot {kg}^{-1} aqueous {KNO}3/0.512 {mol}\\cdot {kg}^{-1} aqueous {K}2{SO}4) systems have been measured for several molal concentrations of amino acid/peptide at different temperatures: T = (298.15 to 323.15) K. Using the speed-of-sound and density data, the parameters, partial molar isentropic compressibilities φ _{kappa }0 and transfer partial molar isentropic compressibilities Δ _{tr} φ _{kappa }0, have been computed. The trends of variation of φ _{kappa }0 and Δ _{tr} φ _{kappa }0 with changes in molal concentration of the solute and temperature have been discussed in terms of zwitterion-ion, zwitterion-water dipole, ion-water dipole, and ion-ion interactions operative in the systems.

  1. Molar mass distribution and solubility modeling of asphaltenes

    SciTech Connect

    Yarranton, H.W.; Masliyah, J.H.

    1996-12-01

    Attempts to model asphaltene solubility with Scatchard-Hildebrand theory were hampered by uncertainty in molar volume and solubility parameter distribution within the asphaltenes. By considering asphaltenes as a series of polyaromatic hydrocarbons with randomly distributed associated functional groups, molar volume and solubility parameter distributions are calculated from experimental measurements of molar mass and density. The molar mass distribution of Athabasca asphaltenes is determined from interfacial tension and vapor pressure osmometry measurements together with plasma desorption mass spectrometry determinations from the literature. Asphaltene densities are calculated indirectly from mixtures of known concentration of asphaltene in toluene. Asphaltene density, molar volume, and solubility parameter are correlated with molar mass. Solid-liquid equilibrium calculations based on solubility theory and the asphaltene property correlations successfully predict experimental data for both the precipitation point and the amount of precipitated asphaltenes in toluene-hexane solvent mixtures.

  2. [Suggestion of new slice thickness mensuration using partial volume effect in magnetic resonance imaging].

    PubMed

    Kimura, Tetsuya; Higashida, Mitsuji; Takatsu, Yasuo; Ogura, Akio

    2011-01-01

    The wedge and the slab methods are standard procedures as slice thickness mensuration of the MRI needs an expensive and exclusive phantom, and they are poor in versatility. We suggest a new method, that we call "differential edge response function method". This is a modified version of the partial method which Higashida and others proposed. In this method, we use an original phantom which has an acrylic disk on the bottom, and take an image of it while moving a slice position so it includes the disk part. We established the region of interest on an image set up and got the edge response function (ERF) from the mean signal intensity and relations of the Z position of the image. In this method, the effective slice thickness is the half width of the slice profile, which is differentiated ERF. This method can be measured even if the linearity of the signal intensity is poor compared to the partial method. It is possible to correct the alignment. In this method the measurement accuracy was approximately equal to the wedge method. This method is minimally influenced by signal-to-noise ratio in comparison with the wedge method. Furthermore, versatility is high, because it is simple and relatively easy to use.

  3. Super-resolution reconstruction in frequency, image, and wavelet domains to reduce through-plane partial voluming in MRI

    SciTech Connect

    Gholipour, Ali Afacan, Onur; Scherrer, Benoit; Prabhu, Sanjay P.; Warfield, Simon K.; Aganj, Iman; Sahin, Mustafa

    2015-12-15

    Purpose: To compare and evaluate the use of super-resolution reconstruction (SRR), in frequency, image, and wavelet domains, to reduce through-plane partial voluming effects in magnetic resonance imaging. Methods: The reconstruction of an isotropic high-resolution image from multiple thick-slice scans has been investigated through techniques in frequency, image, and wavelet domains. Experiments were carried out with thick-slice T2-weighted fast spin echo sequence on the Academic College of Radiology MRI phantom, where the reconstructed images were compared to a reference high-resolution scan using peak signal-to-noise ratio (PSNR), structural similarity image metric (SSIM), mutual information (MI), and the mean absolute error (MAE) of image intensity profiles. The application of super-resolution reconstruction was then examined in retrospective processing of clinical neuroimages of ten pediatric patients with tuberous sclerosis complex (TSC) to reduce through-plane partial voluming for improved 3D delineation and visualization of thin radial bands of white matter abnormalities. Results: Quantitative evaluation results show improvements in all evaluation metrics through super-resolution reconstruction in the frequency, image, and wavelet domains, with the highest values obtained from SRR in the image domain. The metric values for image-domain SRR versus the original axial, coronal, and sagittal images were PSNR = 32.26 vs 32.22, 32.16, 30.65; SSIM = 0.931 vs 0.922, 0.924, 0.918; MI = 0.871 vs 0.842, 0.844, 0.831; and MAE = 5.38 vs 7.34, 7.06, 6.19. All similarity metrics showed high correlations with expert ranking of image resolution with MI showing the highest correlation at 0.943. Qualitative assessment of the neuroimages of ten TSC patients through in-plane and out-of-plane visualization of structures showed the extent of partial voluming effect in a real clinical scenario and its reduction using SRR. Blinded expert evaluation of image resolution in

  4. Effects of partial middle turbinectomy with varying resection volume and location on nasal functions and airflow characteristics by CFD.

    PubMed

    Lee, Kyun Bum; Jeon, Young Sun; Chung, Seung-Kyu; Kim, Sung Kyun

    2016-10-01

    The surgical term "turbinectomy" encompasses many variations in the location and extent of removal. As a systemic approach to consider the negative impact of middle turbinectomy(MT), such as the excessive removal of turbinate, airflows inside a pre-surgery model and a series of virtual surgery models were numerically analyzed and compared. These models simulate three variations of partial MT(three bilateral and three unilateral) with varying resection volume and location. Each middle turbinectomy results in alterations of flow and thermal parameters, such as nasal resistance (NR), velocity, temperature, wall shear stress(WSS) and wall heat transfer(WHT). WSS distributions were also considered in connection with mucosal secretion. The tendency of changes in nasal functions and airflow characteristics was identified with respect to resection volume and location. A counter-rotating vortical structure was seen in the region of widened middle airway for the case of total resection of middle turbinate. Maximum velocity and WSS near sphenopalatine ganglion, which was a possible explanation for headache after total resection of middle turbinate, was increased. Changes in NR and WHT for bi-lateral resection cases were greater than those for unilateral resection cases. While the physiological changes in four partial MT models were insignificant, changes in near total resection model was prominent. Although our surgical simulation was done for a single case, we postulate that the removal of the anterior inferior part of middle turbinate while preserving posterior margin will not alter airflow characteristics extensively. These findings will help designing surgical plans for partial MT.

  5. Effects of partial middle turbinectomy with varying resection volume and location on nasal functions and airflow characteristics by CFD.

    PubMed

    Lee, Kyun Bum; Jeon, Young Sun; Chung, Seung-Kyu; Kim, Sung Kyun

    2016-10-01

    The surgical term "turbinectomy" encompasses many variations in the location and extent of removal. As a systemic approach to consider the negative impact of middle turbinectomy(MT), such as the excessive removal of turbinate, airflows inside a pre-surgery model and a series of virtual surgery models were numerically analyzed and compared. These models simulate three variations of partial MT(three bilateral and three unilateral) with varying resection volume and location. Each middle turbinectomy results in alterations of flow and thermal parameters, such as nasal resistance (NR), velocity, temperature, wall shear stress(WSS) and wall heat transfer(WHT). WSS distributions were also considered in connection with mucosal secretion. The tendency of changes in nasal functions and airflow characteristics was identified with respect to resection volume and location. A counter-rotating vortical structure was seen in the region of widened middle airway for the case of total resection of middle turbinate. Maximum velocity and WSS near sphenopalatine ganglion, which was a possible explanation for headache after total resection of middle turbinate, was increased. Changes in NR and WHT for bi-lateral resection cases were greater than those for unilateral resection cases. While the physiological changes in four partial MT models were insignificant, changes in near total resection model was prominent. Although our surgical simulation was done for a single case, we postulate that the removal of the anterior inferior part of middle turbinate while preserving posterior margin will not alter airflow characteristics extensively. These findings will help designing surgical plans for partial MT. PMID:27598464

  6. Size dependence of cavity volume: a molecular dynamics study.

    PubMed

    Patel, Nisha; Dubins, David N; Pomès, Régis; Chalikian, Tigran V

    2012-02-01

    Partial molar volume, V°, has been used as a tool to sample solute hydration for decades. The efficacy of volumetric investigations of hydration depends on our ability to reliably discriminate between the cavity, V(C), and interaction, V(I), contributions to the partial molar volume. The cavity volume, V(C), consists of the intrinsic volume, V(M), of a solute molecule and the thermal volume, V(T), with the latter representing the volume of the effective void created around the solute. In this work, we use molecular dynamics simulations in conjunction with the Kirkwood-Buff theory to compute the partial molar volumes for organic solutes of varying sizes in water. We perform our computations using the Lennard-Jones and Coulombic pair potentials as well as truncated potentials which contain only the Lennard-Jones but not the Coulombic contribution. The partial molar volume computed with the Lennard-Jones potentials in the absence of the Coulombic term nearly coincides with the cavity volume, V(C). We determine the thermal volume, V(T), for each compound by subtracting its van der Waals volume, V(W), from V(C). Finally, we apply the spherical approximation of solute geometry to evaluate the thickness of the thermal volume, δ. Our results reveal an increase in the thickness of thermal volume, δ, with an increase in the size of the solute. This finding may be related to dewetting of large nonpolar solutes and the concomitant increase in the compressibility of water of hydration. PMID:22133917

  7. 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 β human chorionic gonadotrophin (βhCG) 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 βhCG estimation as well as histological examination of the surgical specimen for all patients coming with features suggestive of ectopic pregnancy. PMID:23238205

  8. High-volume FES-cycling partially reverses bone loss in people with chronic spinal cord injury.

    PubMed

    Frotzler, Angela; Coupaud, Sylvie; Perret, Claudio; Kakebeeke, Tanja H; Hunt, Kenneth J; Donaldson, Nick de N; Eser, Prisca

    2008-07-01

    Spinal cord injury (SCI) leads to severe bone loss in the paralysed limbs and to a resulting increased fracture risk thereof. Since long bone fractures can lead to comorbidities and a reduction in quality of life, it is important to improve bone strength in people with chronic SCI. In this prospective longitudinal cohort study, we investigated whether functional electrical stimulation (FES) induced high-volume cycle training can partially reverse the loss of bone substance in the legs after chronic complete SCI. Eleven participants with motor-sensory complete SCI (mean age 41.9+/-7.5 years; 11.0+/-7.1 years post injury) were recruited. After an initial phase of 14+/-7 weeks of FES muscle conditioning, participants performed on average 3.7+/-0.6 FES-cycling sessions per week, of 58+/-5 min each, over 12 months at each individual's highest power output. Bone and muscle parameters were investigated in the legs by means of peripheral quantitative computed tomography before the muscle conditioning (t1), and after six (t2) and 12 months (t3) of high-volume FES-cycle training. After 12 months of FES-cycling, trabecular and total bone mineral density (BMD) as well as total cross-sectional area in the distal femoral epiphysis increased significantly by 14.4+/-21.1%, 7.0+/-10.8% and 1.2+/-1.5%, respectively. Bone parameters in the femoral shaft showed small but significant decreases, with a reduction of 0.4+/-0.4% in cortical BMD, 1.8+/-3.0% in bone mineral content, and 1.5+/-2.1% in cortical thickness. These decreases mainly occurred between t1 and t2. No significant changes were found in any of the measured bone parameters in the tibia. Muscle CSA at the thigh increased significantly by 35.5+/-18.3%, while fat CSA at the shank decreased by 16.7+/-12.3%. Our results indicate that high-volume FES-cycle training leads to site-specific skeletal changes in the paralysed limbs, with an increase in bone parameters at the actively loaded distal femur but not the passively loaded

  9. Topology-corrected segmentation and local intensity estimates for improved partial volume classification of brain cortex in MRI.

    PubMed

    Rueda, Andrea; Acosta, Oscar; Couprie, Michel; Bourgeat, Pierrick; Fripp, Jurgen; Dowson, Nicholas; Romero, Eduardo; Salvado, Olivier

    2010-05-15

    In magnetic resonance imaging (MRI), accuracy and precision with which brain structures may be quantified are frequently affected by the partial volume (PV) effect. PV is due to the limited spatial resolution of MRI compared to the size of anatomical structures. Accurate classification of mixed voxels and correct estimation of the proportion of each pure tissue (fractional content) may help to increase the precision of cortical thickness estimation in regions where this measure is particularly difficult, such as deep sulci. The contribution of this work is twofold: on the one hand, we propose a new method to label voxels and compute tissue fractional content, integrating a mechanism for detecting sulci with topology preserving operators. On the other hand, we improve the computation of the fractional content of mixed voxels using local estimation of pure tissue intensity means. Accuracy and precision were assessed using simulated and real MR data and comparison with other existing approaches demonstrated the benefits of our method. Significant improvements in gray matter (GM) classification and cortical thickness estimation were brought by the topology correction. The fractional content root mean squared error diminished by 6.3% (p<0.01) on simulated data. The reproducibility error decreased by 8.8% (p<0.001) and the Jaccard similarity measure increased by 3.5% on real data. Furthermore, compared with manually guided expert segmentations, the similarity measure was improved by 12.0% (p<0.001). Thickness estimation with the proposed method showed a higher reproducibility compared with the measure performed after partial volume classification using other methods.

  10. Different partial volume correction methods lead to different conclusions: An (18)F-FDG-PET study of aging.

    PubMed

    Greve, Douglas N; Salat, David H; Bowen, Spencer L; Izquierdo-Garcia, David; Schultz, Aaron P; Catana, Ciprian; Becker, J Alex; Svarer, Claus; Knudsen, Gitte M; Sperling, Reisa A; Johnson, Keith A

    2016-05-15

    A cross-sectional group study of the effects of aging on brain metabolism as measured with (18)F-FDG-PET was performed using several different partial volume correction (PVC) methods: no correction (NoPVC), Meltzer (MZ), Müller-Gärtner (MG), and the symmetric geometric transfer matrix (SGTM) using 99 subjects aged 65-87years from the Harvard Aging Brain study. Sensitivity to parameter selection was tested for MZ and MG. The various methods and parameter settings resulted in an extremely wide range of conclusions as to the effects of age on metabolism, from almost no changes to virtually all of cortical regions showing a decrease with age. Simulations showed that NoPVC had significant bias that made the age effect on metabolism appear to be much larger and more significant than it is. MZ was found to be the same as NoPVC for liberal brain masks; for conservative brain masks, MZ showed few areas correlated with age. MG and SGTM were found to be similar; however, MG was sensitive to a thresholding parameter that can result in data loss. CSF uptake was surprisingly high at about 15% of that in gray matter. The exclusion of CSF from SGTM and MG models, which is almost universally done, caused a substantial loss in the power to detect age-related changes. This diversity of results reflects the literature on the metabolism of aging and suggests that extreme care should be taken when applying PVC or interpreting results that have been corrected for partial volume effects. Using the SGTM, significant age-related changes of about 7% per decade were found in frontal and cingulate cortices as well as primary visual and insular cortices. PMID:26915497

  11. Third molar infections.

    PubMed

    Gutiérrez-Pérez, José Luis

    2004-01-01

    Pericoronitis is an infectious disease often associated with the eruption of a third molar. It can be either acute (serous and suppurative) or chronic. Pain is usually the predominant symptom in acute stages, whereas chronic forms of the disease may display very few symptoms. Both present exudate. The infection is multimicrobial, predominantly caused strictly by betalactamase-producing anaerobeic microorganisms. Treatment measures are symptomatic, antimicrobial and surgical. Antimicrobial treatment is indicated for preoperative prophylaxis when there is a high risk of postoperative infection and, during the acute stages of suppurative pericoronitis when surgery must be postponed. First-line treatment in this case consists of amoxicillin with associated clavulanic acid. Although surgical treatment of pericoronitis presenting at the third molar is indicated as a Grade C recommendation for extraction, it is the most common indication for extraction of a retained third molar, owing to the improved quality of life it can offer the patient.

  12. Apparent molar volume, viscosity, and adiabatic compressibility of some mineral sulfates in aqueous binary mixtures of formamide at 298.15, 308.15, and 318.15 K

    NASA Astrophysics Data System (ADS)

    Roy, M. N.; Chanda, R.; Sarkar, B. K.

    2009-10-01

    The densities and viscosities of several sulfates, viz., ammonium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, zinc sulfate and cadmium sulfate in aqueous binary mixtures of formamide (FA) have been determined at 298.15, 308.15, and 318.15 K and at atmospheric pressure. The ultrasonic speeds of the electrolytic solutions have also been measured at 298.15 K. Apparent molar volumes (ϕ V ), viscosity B-coefficients and adiabatic compressibilities ( K S) of these electrolytic solutions were calculated from the experimental densitiy, viscosity and acoustic data. The density and viscosity data were evaluated by using Masson’s and Jones-Dole equation respectively; the derived parameters have been analyzed in terms of ion-ion and ion-solvent interactions. The structure making/breaking capacities of the electrolytes have been inferred from the sign of (∂2ϕ{/V 0}/ ∂T 2) P . The results showed that all the electrolytes act as structure-makers in these media. Also the compressibility data indicated electrostriction of the solvent molecules around the cations. The activation parameters of viscous flow were also determined and discussed by the application of transition state theory.

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

    NASA Astrophysics Data System (ADS)

    Gallego, J.; Niñerola-Baizán, A.; Cot, A.; Aguiar, P.; Crespo, C.; Falcón, C.; Lomeña, F.; Sempau, J.; Pavía, 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 ({χ2}  ≥ 11.79 for caudate and  ≤7.36 for putamen), standardization based on a simple linear model was also suitable ({χ2}  ≥ 12.44 for caudate and  ≤12.57 for putamen).

  14. Effect of partial volume correction on muscarinic cholinergic receptor imaging with single-photon emission tomography in patients with temporal lobe epilepsy.

    PubMed

    Weckesser, M; Hufnagel, A; Ziemons, K; Griessmeier, M; Sonnenberg, F; Hackländer, T; Langen, K J; Holschbach, M; Elger, C E; Müller-Gärtner, H

    1997-09-01

    Animal experiments and preliminary results in humans have indicated alterations of hippocampal muscarinic acetylcholine receptors (mAChR) in temporal lobe epilepsy. Patients with temporal lobe epilepsy often present with a reduction in hippocampal volume. The aim of this study was to investigate the influence of hippocampal atrophy on the quantification of mAChR with single photon emission tomography (SPET) in patients with temporal lobe epilepsy. Cerebral uptake of the muscarinic cholinergic antagonist [123I]4-iododexetimide (IDex) was investigated by SPET in patients suffering from temporal lobe epilepsy of unilateral (n=6) or predominantly unilateral (n=1) onset. Regions of interest were drawn on co-registered magnetic resonance images. Hippocampal volume was determined in these regions and was used to correct the SPET results for partial volume effects. A ratio of hippocampal IDex binding on the affected side to that on the unaffected side was used to detect changes in muscarinic cholinergic receptor density. Before partial volume correction a decrease in hippocampal IDex binding on the focus side was found in each patient. After partial volume no convincing differences remained. Our results indicate that the reduction in hippocampal IDex binding in patients with epilepsy is due to a decrease in hippocampal volume rather than to a decrease in receptor concentration. PMID:9283110

  15. A new partial volume segmentation approach to extract bladder wall for computer-aided detection in virtual cystoscopy

    NASA Astrophysics Data System (ADS)

    Li, Lihong; Wang, Zigang; Li, Xiang; Wei, Xinzhou; Adler, Howard L.; Huang, Wei; Rizvi, Syed A.; Meng, Hong; Harrington, Donald P.; Liang, Zhengrong

    2004-04-01

    We propose a new partial volume (PV) segmentation scheme to extract bladder wall for computer aided detection (CAD) of bladder lesions using multispectral MR images. Compared with CT images, MR images provide not only a better tissue contrast between bladder wall and bladder lumen, but also the multispectral information. As multispectral images are spatially registered over three-dimensional space, information extracted from them is more valuable than that extracted from each image individually. Furthermore, the intrinsic T1 and T2 contrast of the urine against the bladder wall eliminates the invasive air insufflation procedure. Because the earliest stages of bladder lesion growth tend to develop gradually and migrate slowly from the mucosa into the bladder wall, our proposed PV algorithm quantifies images as percentages of tissues inside each voxel. It preserves both morphology and texture information and provides tissue growth tendency in addition to the anatomical structure. Our CAD system utilizes a multi-scan protocol on dual (full and empty of urine) states of the bladder to extract both geometrical and texture information. Moreover, multi-scan of transverse and coronal MR images eliminates motion artifacts. Experimental results indicate that the presented scheme is feasible towards mass screening and lesion detection for virtual cystoscopy (VC).

  16. Partial-volume effect correction in positron emission tomography brain scan image using super-resolution image reconstruction

    PubMed Central

    Meechai, T; Tepmongkol, S

    2015-01-01

    Objective: The partial-volume effect (PVE) is a consequence of limited (i.e. finite) spatial resolution. PVE can lead to quantitative underestimation of activity concentrations in reconstructed images, which may result in misinterpretation of positron emission tomography (PET) scan images, especially in the brain. The PVE becomes significant when the dimensions of a source region are less than two to three times the full width at half maximum spatial resolution of the imaging system. In the present study, the ability of super-resolution (SR) image reconstruction to compensate for PVE in PET was characterized. Methods: The ability of SR image reconstruction technique to recover activity concentrations in small structures was evaluated by comparing images before and after image reconstruction in the NEMA/IEC phantom (Washington, DC), in the Hoffman brain phantom and in four human brain subjects (three normal subjects and one atrophic brain subject) in terms of apparent recovery coefficient (ARC) and percentage yield. Results: Both the ARC and percentage yield are improved after SR implementation in NEMA/IEC phantom and Hoffman brain phantom. When tested in normal subjects, SR implementation can improve the intensity and justify SR efficiency to correct PVE. Conclusion: SR algorithm can be used to effectively correct PVE in PET images. Advances in knowledge: The current research focused on brain PET scanning exclusively; future work will extend to whole-body imaging. PMID:25492553

  17. 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

  18. 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

  19. 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.

  20. Molar incisor hypomineralization.

    PubMed

    Takahashi, Karine; Correia, Adriana de Sales Cunha; Cunha, Robson Frederico

    2009-01-01

    Enamel defects are common alterations that can occur in both the primary or permanent dentition. A range of etiological factors related to this pathology can be found in the literature. Molar Incisor Hypomineralization (MIH) is a kind of enamel defect alteration that requires complex treatment solutions, and for this reason, it is of great clinical interest for dental practice. This article describes the management of a clinical case of MIH in a 7-year-old child. The different treatment options depending on the extension of the defect, the degree of tooth eruption and the hygiene and diet habits of the patient are also discussed.

  1. 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...

  2. Ectopic molar pregnancy: a case report

    PubMed Central

    Bousfiha, Najoua; Erarhay, Sanaa; Louba, Adnane; Saadi, Hanan; Bouchikhi, Chahrazad; Banani, Abdelaziz; Fatemi, Hind El; Sekkal, Med; Laamarti, Afaf

    2012-01-01

    The incidence of hydatidiform moles is 1 per 1,000 pregnancies. Ectopic pregnancy occurs in 20 per 1,000 pregnancies. Thus, the incidence of the ectopic molar gestation is very rare. We report a case of tubal molar pregnancy diagnosed at the systematic histology exam of an ectopic pregnancy. We report the case of 32 years old nulliparus women who presented a vaginal bleeding, lower abdominal pain and 6 weeks amenorrhea corresponding to the last menstrual period. At the clinical examination, the arterial pressure was 100/60 mmHG. The gynecological examination was difficult because of lower abdominal pain. Serum gonadotropin activity was 3454 ui/l. Pelvic ultrasound revealed an irregular echogenic mass in the left adnexa. Diagnostic laparoscopy revealed a left-sided unruptured ampullary ectopic pregnancy. A left laparoscopic salpingectomy was performed. The systematic histologic test identified an ectopic partial molar pregnancy, which was confirmed by DNA ploidy image analysis. The patient was followed with weekly quantitative B-hCG titers until three successive B-hCG levels were negative. It is pertinent that clinicians take routine histological examination of tubal specimens in ectopic pregnancy very seriously in order to diagnose cases of ectopic molar gestations early and mount appropriate post treatment surveillance. PMID:22655097

  3. Ectopic molar pregnancy: a case report.

    PubMed

    Bousfiha, Najoua; Erarhay, Sanaa; Louba, Adnane; Saadi, Hanan; Bouchikhi, Chahrazad; Banani, Abdelaziz; El Fatemi, Hind; Sekkal, Med; Laamarti, Afaf

    2012-01-01

    The incidence of hydatidiform moles is 1 per 1,000 pregnancies. Ectopic pregnancy occurs in 20 per 1,000 pregnancies. Thus, the incidence of the ectopic molar gestation is very rare. We report a case of tubal molar pregnancy diagnosed at the systematic histology exam of an ectopic pregnancy. We report the case of 32 years old nulliparus women who presented a vaginal bleeding, lower abdominal pain and 6 weeks amenorrhea corresponding to the last menstrual period. At the clinical examination, the arterial pressure was 100/60 mmHG. The gynecological examination was difficult because of lower abdominal pain. Serum gonadotropin activity was 3454 ui/l. Pelvic ultrasound revealed an irregular echogenic mass in the left adnexa. Diagnostic laparoscopy revealed a left-sided unruptured ampullary ectopic pregnancy. A left laparoscopic salpingectomy was performed. The systematic histologic test identified an ectopic partial molar pregnancy, which was confirmed by DNA ploidy image analysis. The patient was followed with weekly quantitative B-hCG titers until three successive B-hCG levels were negative. It is pertinent that clinicians take routine histological examination of tubal specimens in ectopic pregnancy very seriously in order to diagnose cases of ectopic molar gestations early and mount appropriate post treatment surveillance. PMID:22655097

  4. Volumes of aqueous alcohols, ethers, and ketones to T = 523 K and p = 28 MPa.

    PubMed

    Schulte, M D; Shock, E L; Obsil, M; Majer, V

    1999-09-01

    Densities of dilute aqueous solutions of isopropanol, 1,5-pentanediol, cyclohexanol, benzyl alcohol, diethyl ether, 1,2-dimethoxyethane, acetone, and 2,5-hexanedione were measured by means of a vibrating-tube flow densimeter at temperatures near T = (302, 373, 423, 473, and 521) K at a pressure of p = 28 MPa. At the lowest and highest temperatures, measurements were also made close to the saturation vapour pressure of water to investigate the effect of pressure on the volumes of solutes. Apparent molar volumes were calculated for each solute and extrapolated to give partial molar volumes at infinite dilution. The variation of the volume with temperature, pressure, and structure of solute is discussed qualitatively, and group contributions are determined at the temperatures of measurements and p = 28 MPa. Several equations proposed in the literature for correlating the partial molar volumes at infinite dilution as a function of state parameters are tested. Parameters of one selected equation are tabulated allowing calculation of the partial molar volumes at infinite dilution at temperatures and pressures up to T = 573 K and p = 40 MPa. respectively.

  5. The Influence of Treatment Position (Prone vs. Supine) on Clip Displacement, Seroma, Tumor Bed and Partial Breast Target Volumes: Comparative Study.

    PubMed

    Lakosi, Ferenc; Gulyban, Akos; Simoni, Selma Ben-Mustapha; Nguyen, Paul Viet; Cucchiaro, Séverine; Seidel, Laurence; Janvary, Levente; Nicolas, Sophie; Vavassis, Peter; Coucke, Philippe

    2016-07-01

    To analyse the displacement of surgical clips in prone (Pr) position and assess the consequences on target volumes and integral dose of partial breast irradiation (PBI). 30 post-lumpectomy breast cancer patients underwent CT imaging in supine (Su) and Pr. Clip displacements were measured by the distances from the clips to a common fix bony reference point. On each dataset, the tumour bed (TB = clips ± seroma), clinical target volume (CTV = TB + 1.5 cm) and planning target volumes (PTV = CTV + 1 cm) for PBI were determined and the volume pairs were compared. Furthermore estimation of integral dose ratio (IDR) within the breast from tangential treatment was performed as the ratio of the irradiated breast volume and the volume encompassing all clips. Clips close to the chest wall (CW) in Su showed significantly less displacement in Pr. The mean volumes of seroma, CTV and PTV were significantly higher in Pr than in Su. The PTV volume difference (Pr-Su) was significantly higher in patients with presence of seroma, deep clips and TB location in the superior-internal-quadrant (SIQ) and at the junction of superior quadrants (jSQ). In a multivariate analysis two factors remained significant: seroma and TB localization in SIQ-jSQ. The IDR was significantly larger in Su than in Pr (7.6 vs. 4.1 p < 0.01). Clip displacements varied considerably with respect to their relative position to the CW. In selected patients Pr position potentially leads to a significant increase in target volumes of PBI. Tangential beam arrangement for PBI should be avoided, not only in Su but in Pr as well in case of clip-based target volume definition.

  6. When structure affects function--the need for partial volume effect correction in functional and resting state magnetic resonance imaging studies.

    PubMed

    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.

  7. Molar Incisor Hypomineralization.

    PubMed

    Rao, Murali H; Aluru, Srikanth C; Jayam, Cheranjeevi; Bandlapalli, Anila; Patel, Nikunj

    2016-01-01

    Molar incisor hypomineralization (MIH) is a developmental defect affecting teeth. High prevalence rates of MIH and its clinical implications are significant for both the patients and clinicians. A wide variation in defect prevalence (2.4-40.2%) is reported. It seems to differ with regions and various birth cohorts. Some of the recent prevalence studies are tabulated. Patient implications include hypersensitive teeth, rapid progression of caries, mastication impairment due to rapid attrition, and esthetic repercussions. Implications for clinicians include complexity in treatment planning and treatment implementation, poor prognosis of the restorations, difficulty in achieving pain control during treatment, and behavior management problems. Intention of this paper is to review the etio-pathogenesis, prevalence, clinical features, diagnostic features, and eventually present a sequential treatment approach, i.e., in accordance with current clinical practice guidelines. PMID:27595731

  8. Distal caries of the second molar in the presence of a mandibular third molar - a prevention protocol.

    PubMed

    Toedtling, V; Coulthard, P; Thackray, G

    2016-09-23

    Objectives The objectives of the prospective study were to establish the prevalence of distal caries (DC) in the mandibular second molar and to assess the outcomes of these diseased teeth in our population. Further aims were to identify associated risk factors and to design a protocol for prevention.Methods Clinical and radiographic data from 210 consecutive patients were ascertained over a three-month period. The sample population included all patients who had been referred to a hospital oral surgery department for a lower wisdom tooth assessment.Results A total of 224 mandibular third molars were included and assessed. The prevalence of caries affecting the distal aspect of the second molar was 38% (n = 85) in this population. In 18% of patients there was evidence of early enamel caries. Fifty-eight percent of caries was managed with restorative treatment but 11% of patients required second molar extraction and 13% of patients required the removal of the second and third molars. The prevalence of distal caries was significantly higher in patients with partially erupted wisdom teeth positioned below the amelocemental junction (P <0.05) of the adjacent second molar and in patients who presented with mesioangular impactions (P <0.001). However there was no difference in dental health when comparing this group to the remaining study population (P = 0.354). The Pearson chi-square test and Pearson correlation coefficient were used to verify the association between the tested variables.Conclusion This study demonstrates that the eruption status, type of angulation and the nature of tooth contact between both molars are useful disease predictors which can be used to indicate the likelihood of a caries process occurring on the distal aspect of the second mandibular molar. If patients' third molar teeth are not removed then consideration needs to be given to prevention and regular monitoring. PMID:27659630

  9. Digestive cells from Mytilus galloprovincialis show a partial regulatory volume decrease following acute hypotonic stress through mechanisms involving inorganic ions.

    PubMed

    Torre, Agata; Trischitta, Francesca; Corsaro, Carmelo; Mallamace, Domenico; Faggio, Caterina

    2013-08-01

    The response of isolated digestive cells of the digestive gland of Mytilus galloprovincialis to hypotonic shock was studied using videometric methods. The isolated cells exposed to a rapid change (from 1100 to 800 mosmol kg(-1) ) of the bathing solution osmolality swelled but thereafter underwent a regulatory volume decrease (RVD), tending to recover the original size. When the hypotonic stress was applied in the presence of quinine and glibenclamide, known inhibitors of swelling activated ion channels, the cells did not exhibit an RVD response; in addition, they showed a larger increase in size in respect to control cells. These observations suggest that the digestive cells of the digestive gland have the machinery to cope with the hyposmotic shock allowing them to exhibit a small but significant RVD preventing an excessive increase in cell size. The pharmacological treatment of digestive cells during the RVD experiments suggests that cell volume is regulated by K(+) and Cl(-) efflux followed by an obliged water efflux from the cell. The involvement of organic osmolytes such as taurine and betaine seems to be excluded by NMR measurement on digestive cells.

  10. Hypomineralized Second Primary Molars as Predictor of Molar Incisor Hypomineralization.

    PubMed

    Negre-Barber, A; Montiel-Company, J M; Boronat-Catalá, M; Catalá-Pizarro, M; Almerich-Silla, J M

    2016-01-01

    Molar incisor hypomineralization (MIH) is a developmental defect of dental enamel that shares features with hypomineralized second primary molars (HSPM). Prior to permanent tooth eruption, second primary molars could have predictive value for permanent molar and incisor hypomineralization. To assess this possible relationship, a cross-sectional study was conducted in a sample of 414 children aged 8 and 9 years from the INMA cohort in Valencia (Spain). A calibrated examiner (linear-weighted Kappa 0.83) performed the intraoral examinations at the University of Valencia between November 2013 and 2014, applying the diagnostic criteria for MIH and HSPM adopted by the European Academy of Paediatric Dentistry. 100 children (24.2%) presented MIH and 60 (14.5%) presented HSPM. Co-occurrence of the two defects was observed in 11.1% of the children examined. The positive predictive value was 76.7% (63.9-86.6) and the negative predictive value 84.7% (80.6-88.3). The positive likelihood ratio (S/1-E) was 10.3 (5.9-17.9) and the negative likelihood ratio (1-S/E) 0.57 (0.47-0.68). The odds ratio was 18.2 (9.39-35.48). It was concluded that while the presence of HSPM can be considered a predictor of MIH, indicating the need for monitoring and control, the absence of this defect in primary dentition does not rule out the appearance of MIH. PMID:27558479

  11. Hypomineralized Second Primary Molars as Predictor of Molar Incisor Hypomineralization.

    PubMed

    Negre-Barber, A; Montiel-Company, J M; Boronat-Catalá, M; Catalá-Pizarro, M; Almerich-Silla, J M

    2016-08-25

    Molar incisor hypomineralization (MIH) is a developmental defect of dental enamel that shares features with hypomineralized second primary molars (HSPM). Prior to permanent tooth eruption, second primary molars could have predictive value for permanent molar and incisor hypomineralization. To assess this possible relationship, a cross-sectional study was conducted in a sample of 414 children aged 8 and 9 years from the INMA cohort in Valencia (Spain). A calibrated examiner (linear-weighted Kappa 0.83) performed the intraoral examinations at the University of Valencia between November 2013 and 2014, applying the diagnostic criteria for MIH and HSPM adopted by the European Academy of Paediatric Dentistry. 100 children (24.2%) presented MIH and 60 (14.5%) presented HSPM. Co-occurrence of the two defects was observed in 11.1% of the children examined. The positive predictive value was 76.7% (63.9-86.6) and the negative predictive value 84.7% (80.6-88.3). The positive likelihood ratio (S/1-E) was 10.3 (5.9-17.9) and the negative likelihood ratio (1-S/E) 0.57 (0.47-0.68). The odds ratio was 18.2 (9.39-35.48). It was concluded that while the presence of HSPM can be considered a predictor of MIH, indicating the need for monitoring and control, the absence of this defect in primary dentition does not rule out the appearance of MIH.

  12. Molarization of mandibular second premolar.

    PubMed

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

    2014-05-01

    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

  13. Correlation of acute pericoronitis and the position of the mandibular third molar.

    PubMed

    Leone, S A; Edenfield, M J; Cohen, M E

    1986-09-01

    Acute pericoronitis is a painful, debilitating infection that is most commonly found among young adults with erupting mandibular third molars. Prophylactic removal of third molars to prevent this disease has been advocated, but this procedure requires an accurate description of the third molar at highest risk for this infection. Clinical and radiographic measurements were compared in 25 diseased subjects and 109 normal subjects. Of 10 variables significantly related to the presence of acute pericoronitis, stepwise discriminant analysis selected 4 variables that produced a canonical correlation coefficient of 0.71. In clinical terms, these variables described the tooth at highest risk for acute pericoronitis as a fully erupted, vertical mandibular third molar that is in contact with the adjacent second molar, at or above the occlusal plane, and partially encapsulated by soft or hard tissues. Prophylactic treatment of these third molars is highly recommended.

  14. 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.; Hiatt, Jessica R.; Dipetrillo, Thomas A.; Price, Lori Lyn; Wazer, David E.

    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

  15. Hypomineralized Second Primary Molars as Predictor of Molar Incisor Hypomineralization

    PubMed Central

    Negre-Barber, A.; Montiel-Company, J. M.; Boronat-Catalá, M.; Catalá-Pizarro, M.; Almerich-Silla, J. M.

    2016-01-01

    Molar incisor hypomineralization (MIH) is a developmental defect of dental enamel that shares features with hypomineralized second primary molars (HSPM). Prior to permanent tooth eruption, second primary molars could have predictive value for permanent molar and incisor hypomineralization. To assess this possible relationship, a cross-sectional study was conducted in a sample of 414 children aged 8 and 9 years from the INMA cohort in Valencia (Spain). A calibrated examiner (linear-weighted Kappa 0.83) performed the intraoral examinations at the University of Valencia between November 2013 and 2014, applying the diagnostic criteria for MIH and HSPM adopted by the European Academy of Paediatric Dentistry. 100 children (24.2%) presented MIH and 60 (14.5%) presented HSPM. Co-occurrence of the two defects was observed in 11.1% of the children examined. The positive predictive value was 76.7% (63.9–86.6) and the negative predictive value 84.7% (80.6–88.3). The positive likelihood ratio (S/1-E) was 10.3 (5.9–17.9) and the negative likelihood ratio (1-S/E) 0.57 (0.47–0.68). The odds ratio was 18.2 (9.39–35.48). It was concluded that while the presence of HSPM can be considered a predictor of MIH, indicating the need for monitoring and control, the absence of this defect in primary dentition does not rule out the appearance of MIH. PMID:27558479

  16. Supernumerary molars. A review of 53 cases.

    PubMed

    Menardía-Pejuan, V; Berini-Aytés, L; Gay-Escoda, C

    2000-01-01

    Supernumerary molars are not uncommon and may be found nearly anywhere in the dental alveolar arches. A series of 36 patients that presented with 53 supernumerary molars are reviewed. They occurred more frequently in the maxilla (86.8%), had little or no clinical significance, tended to be impacted, and were not associated with the impactation of the third molar. Four cases of maxillary fifth molars are described. PMID:11799727

  17. 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; Fox, Stephen; Hill, Prudence; Collins, Marnie; Chua, Boon H.

    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.

  18. 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.

  19. Molar versus as a paradigm clash.

    PubMed Central

    Baum, W M

    2001-01-01

    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

  20. [Distalization of the upper second molar: biomechanics].

    PubMed

    Castaldo, A

    1991-01-01

    The Author shows a system to dystalize the second upper molars and, if necessary, the third upper molars. This system, easy to be adapted, is made up by a palatal bar inserted between the first upper molars, by a sectional and a 100 grams precalibrated open Sentalloy coil spring used as an active force. PMID:1784296

  1. Effect of varying alveolar oxygen partial pressure on diffusing capacity for nitric oxide and carbon monoxide, membrane diffusing capacity and lung capillary blood volume.

    PubMed

    Borland, C D; Cox, Y

    1991-12-01

    1. To examine the effect of varying oxygen partial pressure (PAO2) on nitric oxide (DLNO) and carbon monoxide (DLCO) diffusing capacity (transfer factor), 10 subjects performed combined DLCO/DLNO measurements with the inspired mixture made up with three different oxygen concentrations (25%, 18% and 15%) to give PAO2 values of 12-20 kPa. 2. A novel method is described for calculating membrane diffusing capacity (DM) and pulmonary capillary volume (Qc) from DLNO and DLCO. 3. The mean DMCO was 52.89 mmol min-1 kPa-1 and Qc was 0.056 litre. Reducing PAO2 from 20 to 12 kPa resulted in an increase in DLCO = -0.124 (O2%) + 11.67 (P less than 0.001) and a fall in DLNO = 0.538 (O2%) + 32.01 (P less than 0.001) and a fall in DLNO/DLCO = 0.107 (O2%) + 2.52 (P less than 0.001). DM (P = 0.59) and Qc (P = 0.64) also tended to fall with falling PAO2. 4. It appears more likely that the minor reduction in DLNO that we have observed with falling PAO2 is due to diffusion rather than reaction limitation.

  2. Assessment of the severity of partial volume effects and the performance of two template-based correction methods in a SPECT/CT phantom experiment.

    PubMed

    Shcherbinin, S; Celler, A

    2011-08-21

    We investigated the severity of partial volume effects (PVE), which may occur in SPECT/CT studies, and the performance of two template-based correction techniques. A hybrid SPECT/CT system was used to scan a thorax phantom that included lungs, a heart insert and six cylindrical containers of different sizes and activity concentrations. This phantom configuration allowed us to have non-uniform background activity and a combination of spill-in and spill-out effects for several compartments. The reconstruction with corrections for attenuation, scatter and resolution loss but not PVE correction accurately recovered absolute activities in large organs. However, the activities inside segmented 17-120 mL containers were underestimated by 20%-40%. After applying our PVE correction to the data pertaining to six small containers, the accuracy of the recovered total activity improved with errors ranging between 3% and 22% (non-iterative method) and between 5% and 15% (method with an iteratively updated background activity). While the non-iterative template-based algorithm demonstrated slightly better accuracy for cases with less severe PVE than the iterative algorithm, it underperformed in situations with considerable spill out and/or mixture of spill-in and spill-out effects.

  3. 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.

  4. Intrusion of an overerupted molar using orthodontic miniscrew implant: A preprosthodontic therapy

    PubMed Central

    Sivakumar, Indumathi; Sivakumar, Arunachalam

    2014-01-01

    The purpose of this case report is to demonstrate the use of orthodontic miniscrew implant in the intrusion of overerupted molar as a preprosthodontic therapy. A 37-year-old woman with an overerupted maxillary right first molar encroaching on the opposing mandibular edentulous space was successfully intruded using a single miniscrew implant and partial fixed orthodontic appliance. The prosthodontic clinician may adopt this conservative and cost-effective strategy in their routine practice and avoid clinical crown reduction. PMID:25191088

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

    PubMed

    Brendel, Matthias; Högenauer, 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

  6. [Molar pregnancy (primary or recurrent?)].

    PubMed

    Ayala, A; Aizpuru, E; Tovar, J M

    1989-08-01

    A peculiar case of gestational trophoblastic disease is described. A 24 year old female with former history of three molar pregnancies, spontaneous abortion and anembryoic pregnancy was admitted because of a newly diagnosed hydatiform mole (ex novo). After uterine curettage followed by a low oral dose of methotrexate (0.5 mg/kg/day) for five days. The HCG levels determined in plasma by beta-HCG- radioinmmunoassay, became negative until four months of follow3 up. An intrauterine device was installed. She resumed HCG positivity a year later and a histerectomy was performed. A post-surgical diagnosis of invasive mole was made. Since the possibility of intercurrent pregnancy was lowered by the presence of a intrauterine device, we assumed that trophoblastic transformation into an invasive mole adopted a sort of dormant period before its resurge (resurrection) independently either from curettage of chemotherapy.

  7. 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.

  8. 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

  9. 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: 0.91–0.97) than SWE (DSCs: 0.68–0.79) 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

  10. 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

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

    PubMed

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

    2013-10-21

    Kinetic parameters estimated from dynamic (18)F-fluorodeoxyglucose ((18)F-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 (18)F-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

  12. 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

  13. Histological evaluation of mandibular third molar roots retrieved after coronectomy.

    PubMed

    Patel, Vinod; Sproat, Chris; Kwok, Jerry; Beneng, Kiran; Thavaraj, Selvam; McGurk, Mark

    2014-05-01

    There is a resurgence of interest in coronectomy for the management of mandibular third molars because it has a low risk of injury to the inferior dental nerve. However, there is concern that the root that is left in place will eventually become a source of infection. We describe the histological evaluation of 26 consecutive symptomatic coronectomy roots in 21 patients. All roots had vital tissue in the pulp chamber and there was no evidence of periradicular inflammation. Persistent postoperative symptoms related predominantly to inflammation of the soft tissue, which was caused by partially erupted roots or failure of the socket to heal. PMID:24684971

  14. Expressly Fabricated Molar Tube Bases: Enhanced Adhesion

    PubMed Central

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

    2014-01-01

    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

  15. 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

  16. Maxillary second molar impaction in the adjacent ectopic third molar: Report of five rare cases

    PubMed Central

    Souki, Bernardo Q.; Cheib, Paula L.; de Brito, Gabriela M.; Pinto, Larissa S. M. C.

    2015-01-01

    Maxillary second molar impaction in the adjacent ectopic third molar is a rare condition that practitioners might face in the field of pediatric dentistry and orthodontics. The early diagnosis and extraction of the adjacent ectopic third molar have been advocated, and prior research has reported a high rate of spontaneous eruption following third molar removal. However, some challenges in the daily practice are that the early diagnosis of this type of tooth impaction is difficult with conventional radiographic examination, and sometimes the early surgical removal of the maxillary third molar must be postponed because of the risks of damaging the second molar. The objective of this study is to report a case series of five young patients with maxillary second molar impaction and to discuss the difficulty of early diagnosis with the conventional radiographic examination, and unpredictability of self-correction. PMID:26321848

  17. Sextant of Sapphires for Molar Distalization

    PubMed Central

    Palla, Yudistar Venkata; Ganugapanta, Vivek Reddy

    2016-01-01

    Introduction Space analysis quantifies the amount of crowding within the arches estimating the severity of space discrepancy. The space gaining procedures include extraction and non-extraction procedures like expansion, proximal stripping and molar distalization. Aim To identify features seen in molar distalization cases. Materials and Methods The sample size comprised 20 patients in whom molar distalization was decided as the treatment plan. The study models and lateral cephalograms of all the patients were taken. Occlusograms were obtained. Model analysis and cephalometric analysis were performed. Descriptive statistical analysis like mean, standard deviation, standard error and mode were done. Results The parameters in Question gave following results. The Bolton analysis showed anterior mandibular excess with mean value of 1.56mm±1.07. The first order discrepancy between maxillary central and lateral incisors was 5±1.95. The premolar rotation showed mean value of 16.58±5.12. The molar rotation showed the value of 7.66±2.26. The nasolabial angle showed the mean of 101.25±8.7 IMPA of 101.4±5.74. Conclusion The six features studied in molar distalization cases [First order discrepancy between upper central and lateral incisors; Rotation of premolars and molars; Bolton’s discrepancy in anterior dentition; Average to horizontal growth pattern; Proclined lower incisors and Obtuse nasolabial angle] can be taken as patterns seen in molar distalization cases and considered as a valid treatment plan. PMID:27656572

  18. Intracoronal radiolucency in an incompletely erupted permanent molar with a diagnosis of pericoronitis: importance of radiographic examination.

    PubMed

    Segura, J J; Jiménez-Rubio, A; Cabrera, R

    1998-04-01

    Because of clinical signs and symptoms, a diagnosis of pericoronitis in a partially erupted, partially impacted first molar was made. A more thorough diagnosis was made with the help of a periapical radiograph that showed caries and thus revealed an irreversible pulpitis. Appropriate treatment was the result.

  19. Maxillary second molar extractions in orthodontic treatment.

    PubMed

    Lee, Wilson; Wong, Ricky Wing-Kit; Ikegami, Tomio; Hägg, 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.

  20. Maxillary first molar with five canals

    PubMed Central

    Umer, Fahad

    2014-01-01

    Root canal treatment is a technically demanding procedure especially in the case of maxillary first molar where the anatomy is extremely variable. Failure to recognise and treat these variations may lead to unpredictable outcomes. This case report describes non-surgical endodontic treatment of a maxillary first molar with two palatal and two mesiobuccal canals. It also highlights the need for good anatomical knowledge of root canal morphology and its variations in order to achieve consistently successful results. PMID:25239993

  1. Maxillary molar distalization with first class appliance

    PubMed Central

    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

  2. Molar shape variability in platyrrhine primates.

    PubMed

    Nova Delgado, Mónica; Galbany, Jordi; Pérez-Pérez, Alejandro

    2016-10-01

    Recent phylogenetic analyses suggest that platyrrhines constitute a monophyletic group represented by three families: Cebidae, Atelidae, and Pitheciidae. Morphological variability between and within these three families, however, is widely discussed and debated. The aim of this study was to assess molar shape variability in platyrrhines, to explore patterns of interspecific variation among extant species, and to evaluate how molar shape can be used as a taxonomic indicator. The analyses were conducted using standard multivariate analyses of geometric morphometric data from 802 platyrrhine lower molars. The results indicated that the interspecific variation exhibited a highly homoplastic pattern related to functional adaptation of some taxa. However, phylogeny was also an important factor in shaping molar morphological traits, given that some phenotypic similarities were consistent with current phylogenetic positions. Our results show that the phylogenetic and functional signals of lower molar shape vary depending on the taxa and the tooth considered. Based on molar shape, Aotus showed closer similarities to Callicebus, as well as to some Cebidae and Ateles-Lagothrix, due to convergent evolutionary trends caused by similar dietary habits, or due to fast-evolving branches in the Aotus lineage, somewhat similar to the shape of Callicebus and Cebidae.

  3. Molar shape variability in platyrrhine primates.

    PubMed

    Nova Delgado, Mónica; Galbany, Jordi; Pérez-Pérez, Alejandro

    2016-10-01

    Recent phylogenetic analyses suggest that platyrrhines constitute a monophyletic group represented by three families: Cebidae, Atelidae, and Pitheciidae. Morphological variability between and within these three families, however, is widely discussed and debated. The aim of this study was to assess molar shape variability in platyrrhines, to explore patterns of interspecific variation among extant species, and to evaluate how molar shape can be used as a taxonomic indicator. The analyses were conducted using standard multivariate analyses of geometric morphometric data from 802 platyrrhine lower molars. The results indicated that the interspecific variation exhibited a highly homoplastic pattern related to functional adaptation of some taxa. However, phylogeny was also an important factor in shaping molar morphological traits, given that some phenotypic similarities were consistent with current phylogenetic positions. Our results show that the phylogenetic and functional signals of lower molar shape vary depending on the taxa and the tooth considered. Based on molar shape, Aotus showed closer similarities to Callicebus, as well as to some Cebidae and Ateles-Lagothrix, due to convergent evolutionary trends caused by similar dietary habits, or due to fast-evolving branches in the Aotus lineage, somewhat similar to the shape of Callicebus and Cebidae. PMID:27650581

  4. 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.

  5. 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

  6. Brodie bite with an extracted mandibular first molar in a young adult: a case report.

    PubMed

    Chugh, Vinay K; Sharma, Vijay P; Tandon, Pradeep; Singh, Gyan P

    2010-05-01

    Total buccal crossbites are rare, but, when they occur, they can be extremely difficult to correct, even with surgery and orthodontics. In most patients with in-locking crossbites, the maxillary teeth erupt past their mandibular antagonists, creating severe occlusal difficulties. This article presents an adult patient with scissors-bite or partial telescoping bite bilaterally in the posterior region and an extracted mandibular first molar on the right side. She was treated with expansion of the mandibular arch, and the subsequent open bite was closed with the help of masticatory muscle exercises and high-pull headgear. The second and third molars were uprighted and moved mesially to close the extraction spaces.

  7. Diagnosis of molar pregnancy and persistent trophoblastic disease by flow cytometry.

    PubMed Central

    Hemming, J D; Quirke, P; Womack, C; Wells, M; Elston, C W; Bird, C C

    1987-01-01

    Histopathological assessment and flow cytometric analyses were carried out on 32 placentas (representative of each trimester) and 88 molar pregnancies. Three first trimester placentas were triploid, and the remaining 29 placentas were diploid. Of the 88 cases originally diagnosed as molar pregnancies, 26 were triploid (two complete moles, 20 partial moles, and four hydropic abortions); 59 were diploid (46 complete moles, 10 partial moles, three hydropic abortions); one was tetraploid (partial mole); and two were DNA aneuploid (one partial mole, one complete mole). A significantly increased hyperdiploid fraction (a measure of cell proliferation) was detected in diploid complete moles (p less than 0.0001) and cases of persistent trophoblastic disease (p less than 0.001) when compared with diploid placentas and diploid partial moles. All seven cases of established persistent trophoblastic disease, for which follow up was available, were diploid and showed high hyperdiploid fractions within the range for diploid complete moles. These findings suggest that flow cytometric DNA measurements may be an important aid in the diagnosis of molar pregnancy. The high degree of cell proliferation found in this study may explain the premalignant potential of complete hydatidiform moles. PMID:3611391

  8. Orthodontic extrusion of horizontally impacted mandibular molars

    PubMed Central

    Ma, Zhigui; Yang, Chi; Zhang, Shanyong; Xie, Qianyang; Shen, Yuqing; Shen, Pei

    2014-01-01

    Objective: To introduce and evaluate a novel approach in treating horizontally impacted mandibular second and third molars. Materials and methods: An orthodontic technique was applied for treatment of horizontally impacted mandibular second and third molars, which included a push-type spring for rotation first, and then a cantilever for extrusion. There were 8 mandibular third molars (M3s) and 2 second molars (M2s) in this study. Tooth mobility, extraction time, the inclination and parallelism of the impacted tooth, alveolar bone height of the adjacent tooth, and the relationship of impacted M3 and the inferior alveolar nerve (IAN) were evaluated. Results: Two horizontally impacted M2s could be upright in the arch and good occlusal relationships were obtained after treatment. All impacted M3s were successfully separated from the IAN, without any neurologic consequences. The average extraction time was 5 minutes. There was a significant change in the inclination and parallelism of the impacted tooth after treatment. A new bone apposition with the average height of 3.2 mm was noted distal to the adjacent tooth. Conclusions: This two-step orthodontic technique as presented here may be a safe and feasible alternative in management of severely horizontally impacted mandibular molars, which achieves a successful separation of M3s from the IAN and an excellent position for M2s. PMID:25419364

  9. 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.

  10. Lower third molar eruption following orthodontic treatment.

    PubMed

    Salehi, P; Danaie, S Momene

    2008-01-01

    This study assessed the effect of extraction and preservation of the 1st premolar on lower 3rd molar eruption. Orthodontic clinic records from 1993 to 1995 were evaluated before and after treatment and 8-9 years after treatment for 3 groups of patients: 32 with extraction of 1st premolars in both jaws, 32 with no extraction but orthodontic treatment and 48 controls with no extraction but orthodontic treatment in the upper jaws only. Successful eruption of 3rd molars was evaluated. There was a significant difference in the rates of successful eruptions in the extraction (42%), non-extraction (12%) and control (20%) groups. The findings indicate that 1st premolar extraction may increase the chance of 3rd molar eruption, leading to a lower incidence of health and economic complications.

  11. Lower third molar eruption following orthodontic treatment.

    PubMed

    Salehi, P; Danaie, S Momene

    2008-01-01

    This study assessed the effect of extraction and preservation of the 1st premolar on lower 3rd molar eruption. Orthodontic clinic records from 1993 to 1995 were evaluated before and after treatment and 8-9 years after treatment for 3 groups of patients: 32 with extraction of 1st premolars in both jaws, 32 with no extraction but orthodontic treatment and 48 controls with no extraction but orthodontic treatment in the upper jaws only. Successful eruption of 3rd molars was evaluated. There was a significant difference in the rates of successful eruptions in the extraction (42%), non-extraction (12%) and control (20%) groups. The findings indicate that 1st premolar extraction may increase the chance of 3rd molar eruption, leading to a lower incidence of health and economic complications. PMID:19161121

  12. Fabrication and Evaluation of a Noncompliant Molar Distalizing Appliance: Bonded Molar Distalizer

    PubMed Central

    Sodagar, A.; Ahmad Akhoundi, M. S.; Rafighii, A.; Arab, S.

    2011-01-01

    Objective Attempts to treat class II malocclusions without extraction in non-compliant patients have led to utilization of intraoral molar distalizing appliances. The purpose of this study was to investigate dental and skeletal effects of Bonded Molar Distalizer (BMD) which is a simple molar distalizing appliance. Materials and Methods Sixteen patients (12 girls, four boys) with bilateral half-cusp class II molar relationship, erupted permanent second molars and normal or vertical growth pattern were selected for bilateral distalization of maxillary molars via BMD. The screws were activated every other day, alternately. Lateral cephalograms and study models were obtained before treatment and after 11 weeks activation of the appliance. Results Significant amounts of molar distalization, molar distal tipping and anchorage loss were observed. The mean maxillary first molar distal movement was 1.22±0.936 mm with a distal tipping of 2.97±3.74 degrees in 11 weeks. The rate of distal movement was 0.48 mm per month. Reciprocal mesial movement of the first premolars was 2.26±1.12 mm with a mesial tipping of 4.25±3.12 degrees. Maxillary incisors moved 3.55±1.46 mm and tipped 9.87±5.03 degrees mesially. Lower anterior face height (LAFH) decreased 1.28±1.36 mm. Conclusion BMD is appropriate for distalizing maxillary molars, especially in patients with critical LAFH, although significant amounts of anchorage loss occur using this appliance. PMID:22457837

  13. Molar and molecular views of choice.

    PubMed

    Baum, William M

    2004-06-30

    The molar and molecular views of behavior are not different theories or levels of analysis; they are different paradigms. The molecular paradigm views behavior as composed of discrete units (responses) occurring at moments in time and strung together in chains to make up complex performances. The discrete pieces are held together as a result of association by contiguity. The molecular view has a long history both in early thought about reflexes and in associationism, and, although it was helpful to getting a science of behavior started, it has outlived its usefulness. The molar view stems from a conviction that behavior is continuous, as argued by John Dewey, Gestalt psychologists, Karl Lashley, and others. The molar paradigm views behavior as inherently extended in time and composed of activities that have integrated parts. In the molar paradigm, activities vary in their scale of organization--i.e., as to whether they are local or extended--and behavior may be controlled sometimes by short-term relations and sometimes by long-term relations. Applied to choice, the molar paradigm rests on two simple principles: (a) all behavior constitutes choice; and (b) all activities take time. Equivalence between choice and behavior occurs because every situation contains more than one alternative activity. The principle that behavior takes time refers not simply to any notion of response duration, but to the necessity that identifying one action or another requires a sample extended in time. The molecular paradigm's momentary responses are inferred from extended samples in retrospect. In this sense, momentary responses constitute abstractions, whereas extended activities constitute concrete particulars. Explanations conceived within the molecular paradigm invariably involve hypothetical constructs, because they require causes to be contiguous with responses. Explanations conceived within the molar paradigm retain direct contact with observable variables.

  14. Pathological (late) fractures of the mandibular angle after lower third molar removal: a case series

    PubMed Central

    2013-01-01

    Introduction Pathological (late) fracture of the mandibular angle after third molar surgery is very rare (0.005% of third molar removals). There are 94 cases reported in the literature; cases associated with osseous pathologies such as osteomyelitis or any local and systemic diseases that may compromise mandibular bone strength have not been included. We describe three new cases of pathological (late) fracture of the mandibular angle after third molar surgery. Case presentations The first patient was a 27-year-old Caucasian man who had undergone surgical removal of a 3.8, mesioangular variety, class II-C third molar 20 days before admission to our clinic. The fracture of his left mandibular angle, complete and composed, occurred during chewing. The second patient was a 32-year-old Caucasian man. He had undergone surgical removal of a 3.8, mesioangular variety, class II-B third molar 22 days before his admission. The fracture, which occurred during mastication, was studied by computed tomography that showed reparative tissue in the fracture site. The third patient was a 36-year-old Caucasian man who had undergone surgical removal of a 3.8, vertical variety, class II-C third molar 25 days before the observation. In this case the fracture of his mandibular angle was oblique (unfavorable), complete and composed. The fracture had occurred during chewing. We studied the fracture by optical projection tomography and computed tomography. All of the surgical removals of the 3.8 third molars, performed by the patients’ dentists who had more than 10 years of experience, were difficult. We treated the fractures with open surgical reduction, internal fixation by titanium miniplates and intermaxillary elastic fixation removed after 6 weeks. Conclusions The literature indicates that the risk of pathological (late) fracture of the mandibular angle after third molar surgery for total inclusions (class II-III, type C) is twice that of partial inclusions due to the necessity of

  15. Hydrated nonpolar solute volumes: Interplay between size, Attractiveness, and molecular structure.

    PubMed

    Ashbaugh, Henry S; Barnett, J Wesley; da Silva Moura, Natalia; Houser, Hayden E

    2016-06-01

    A solute's partial molar volume determines its response to pressure, which can result in changes in molecular conformation or assembly state. Computing speed advances have made accurate partial molar volume evaluation in water routine, allowing for the dissection of the molecular factors underlying this significant thermodynamic variable. A recent simulation analysis of the volumes of nonpolar molecular solutes in water reported that the apparent solvent-free border thickness enshrouding these solutes grows with increasing solute size, based on the assumption the solute can be treated as an individual sphere [Biophys. Chem. 161 (2012) 46]. This suggests the solvent dewets these solutes as they grow in size. Via simulations of dewetted repulsive spherical solutes, we show that the border thicknesses of the largest non-polar molecular solutes tend towards that of a repulsive sphere. When attractive interactions are accounted for, however, the spherical solute border thicknesses fall below that of the largest molecular solutes. We demonstrate that if the molecular solutes are treated with atomic detail rather than approximated as an individual sphere, the border thickness variation is minimal. A geometric model is put forward that reproduces the inferred border thickening, indicating the implied dewetting results from a breakdown in the spherical volume approximation. PMID:27058292

  16. Mass versus molar doses, similarities and differences.

    PubMed

    Chmielewska, A; Lamparczyk, H

    2008-11-01

    Generally, they are two systems expressing the amounts of active substance in a given drug product, i.e. mass and molar dose. Currently, the dose system based on the mass is widely used in which doses are expressed in grams or milligrams. On the other hand, the molar dose system is in direct relation to the number of molecules. Hence, the objective of this work was to compare both systems in order to find their advantages and disadvantages. Active substances belonging to the groups of antibiotics, nootropic agents, beta-blockers, vitamins, GABA-analog, COX-2 inhibitors, calcium channel antagonists, benzodiazepine receptor agonists, lipid-modifying agents (fibrates), non-steroidal anti-inflammatory drugs (profens), estrogens, neuroleptics, analgesics and benzodiazepines were considered. Moreover, products containing two active substances were also taken into account. These are mixtures of hydrochlorothiazide with active substances influencing the renin-angiotensin system and combined oral contraceptives. For each active substance, belonging to the groups mentioned above molar doses were calculated from mass doses and molar mass. Hence, groups of drugs with a single active substance, drugs with similar pharmacological activities, pharmaceutical alternatives, and drugs with a single active ingredient manufactured in different doses were compared in order to find which dose system describes more adequately differences between and within the groups mentioned above. Comparisons were supported by a number of equations, which theoretically justify the data, and relationships derived from calculations. PMID:19069248

  17. Raman Line Imaging of Poly(ε-caprolactone)/Carbon Dioxide Solutions at High Pressures: A Combined Experimental and Computational Study for Interpreting Intermolecular Interactions and Free-Volume Effects.

    PubMed

    Pastore Carbone, Maria Giovanna; Musto, Pellegrino; Pannico, Marianna; Braeuer, Andreas; Scherillo, Giuseppe; Mensitieri, Giuseppe; Di Maio, Ernesto

    2016-09-01

    In the present study, a Raman line-imaging setup was employed to monitor in situ the CO2 sorption at elevated pressures (from 0.62 to 7.10 MPa) in molten PCL. The method allowed the quantitative measurement of gas concentration in both the time-resolved and the space-resolved modes. The combined experimental and theoretical approach allowed a molecular level characterization of the system. The dissolved CO2 was found to occupy a volume essentially coincident with its van der Waals volume and the estimated partial molar volume of the probe did not change with pressure. Lewis acid-Lewis base interactions with the PCL carbonyls was confirmed to be the main interaction mechanism. The geometry of the supramolecular complex and the preferential interaction site were controlled more by steric than electronic effects. On the basis of the indications emerging from Raman spectroscopy, an equation of state thermodynamic model for the PCL-CO2 system, based upon a compressible lattice fluid theory endowed with specific interactions, has been tailored to account for the interaction types detected spectroscopically. The predictions of the thermodynamic model in terms of molar volume of solution have been compared with available volumetric measurements while predictions for CO2 partial molar volume have been compared with the values estimated on the basis of Raman spectroscopy. PMID:27454947

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

    PubMed

    Rajasuo, Ari; Peltola, Jaakko; Ventä, 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.

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

    PubMed

    Rajasuo, Ari; Peltola, Jaakko; Ventä, 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

  20. 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

  1. Till Surgery do us Part: Unexpected Bilateral Kissing Molars

    PubMed Central

    Anish, Narayanankutty; Vivek, Velayudhannair; Thomas, Sunila; Daniel, Vineet Alex; Thomas, Jincy; Ranimol, Prasanna

    2015-01-01

    The occurrence impacted teeth, single or multiple is very common. But, phenomenon of kissing molars is an extremely rare phenomenon. Mandibular third molars are the most common impacted teeth. Mandibular first or second molars does not share the same frequency of occurrence. But, there are rare cases in which the occlusal surfaces of impacted molars are united by the same follicular space and the roots point in the opposite direction, and are termed as kissing molars. Sometimes, these teeth will be associated with pathologies. This article reports a rare case of mandibular bilateral kissing molars. PMID:25918627

  2. 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

  3. 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 23 years, 25 gender-specific radiographs were collected within each age category of 1 year. Third molar development was classified and registered according the 10-point staging and scoring technique proposed by Gleiser and Hunt (1955), modified by Köhler (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 % R² increase and a 0.10-year decrease of RMSE. Forensic dental age estimations on panoramic radiographic data in the subadult group (15-23 year) should only be based on third molar development.

  4. Applications of tissue heterogeneity corrections and biologically effective dose volume histograms in assessing the doses for accelerated partial breast irradiation using an electronic brachytherapy source

    NASA Astrophysics Data System (ADS)

    Shi, Chengyu; Guo, Bingqi; Cheng, Chih-Yao; Eng, Tony; Papanikolaou, Nikos

    2010-09-01

    A low-energy electronic brachytherapy source (EBS), the model S700 Axxent™ x-ray device developed by Xoft Inc., has been used in high dose rate (HDR) intracavitary accelerated partial breast irradiation (APBI) as an alternative to an Ir-192 source. The prescription dose and delivery schema of the electronic brachytherapy APBI plan are the same as the Ir-192 plan. However, due to its lower mean energy than the Ir-192 source, an EBS plan has dosimetric and biological features different from an Ir-192 source plan. Current brachytherapy treatment planning methods may have large errors in treatment outcome prediction for an EBS plan. Two main factors contribute to the errors: the dosimetric influence of tissue heterogeneities and the enhancement of relative biological effectiveness (RBE) of electronic brachytherapy. This study quantified the effects of these two factors and revisited the plan quality of electronic brachytherapy APBI. The influence of tissue heterogeneities is studied by a Monte Carlo method and heterogeneous 'virtual patient' phantoms created from CT images and structure contours; the effect of RBE enhancement in the treatment outcome was estimated by biologically effective dose (BED) distribution. Ten electronic brachytherapy APBI cases were studied. The results showed that, for electronic brachytherapy cases, tissue heterogeneities and patient boundary effect decreased dose to the target and skin but increased dose to the bones. On average, the target dose coverage PTV V100 reduced from 95.0% in water phantoms (planned) to only 66.7% in virtual patient phantoms (actual). The actual maximum dose to the ribs is 3.3 times higher than the planned dose; the actual mean dose to the ipsilateral breast and maximum dose to the skin were reduced by 22% and 17%, respectively. Combining the effect of tissue heterogeneities and RBE enhancement, BED coverage of the target was 89.9% in virtual patient phantoms with RBE enhancement (actual BED) as compared to 95

  5. 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.

  6. Removal of Deeply Impacted Mandibular Molars by Sagittal Split Osteotomy.

    PubMed

    Cansiz, Erol; Isler, Sabri Cemil; Gultekin, B Alper

    2016-01-01

    Mandibular third molars are the most common impacted teeth. Mandibular first and second molars do not share the same frequency of occurrence. In rare cases the occlusal surfaces of impacted molars are united by the same follicular space and the roots pointing in opposite direction; these are called kissing molars. In some cases, a supernumerary fourth molar can be seen as unerupted and, in this case, such a supernumerary, deeply impacted fourth molar is seen neighboring kissing molars. The extraction of deeply impacted wisdom molars from the mandible may necessitate excessive bone removal and it causes complications such as damage to the inferior alveolar nerve and iatrogenic fractures of the mandible. This case report describes the use of the sagittal split osteotomy technique to avoid extensive bone removal and protect the inferior alveolar nerve during surgical extruction of multiple impacted teeth.

  7. Removal of Deeply Impacted Mandibular Molars by Sagittal Split Osteotomy

    PubMed Central

    Isler, Sabri Cemil

    2016-01-01

    Mandibular third molars are the most common impacted teeth. Mandibular first and second molars do not share the same frequency of occurrence. In rare cases the occlusal surfaces of impacted molars are united by the same follicular space and the roots pointing in opposite direction; these are called kissing molars. In some cases, a supernumerary fourth molar can be seen as unerupted and, in this case, such a supernumerary, deeply impacted fourth molar is seen neighboring kissing molars. The extraction of deeply impacted wisdom molars from the mandible may necessitate excessive bone removal and it causes complications such as damage to the inferior alveolar nerve and iatrogenic fractures of the mandible. This case report describes the use of the sagittal split osteotomy technique to avoid extensive bone removal and protect the inferior alveolar nerve during surgical extruction of multiple impacted teeth. PMID:27429810

  8. Enzyme Molar Fractions: A Powerful Tool for Understanding Enzyme Kinetics.

    ERIC Educational Resources Information Center

    Serra, Juan L.; And Others

    1986-01-01

    Deduces the relationship between reduced velocity and molar fractions for productive enzyme complexes; obtains the mathematical expression of molar fractions for an enzyme with two specific binding sites per molecule; and proposes a useful plot to follow the dependence of enzyme molar fractions with the concentration of one of its ligands. (JN)

  9. The effect of buffer molarity on axonal exposure and axoaxonal apposition in the rat molar pulp.

    PubMed

    Holland, G R

    1981-11-01

    Axons in the rat molar pulp have been examined morphometrically to determine axonal size and the degree of axonal exposure and axoaxonal apposition in tissue fixed by perfusion using 2% glutaraldehyde in cacodylate buffers ranging in molarity form 0.025 M to 0.4 M. Between 31.2% and 45.0% of the axons were incompletely ensheathed. This proportion of axons exposed was linearly related to the buffer molarity (P less than 0.05) and was approximately double that found in more central axons. Between 32.3% and 45.0% of the axons were in contact with other axons. This proportion was not linearly related to buffer molarity but was least ten times higher than that observed in more centrally positioned nerve fibers in the inferior alveolar nerves. Increasing buffer molarity reduced the size of the axons, a relationship not found in the more central axons. It is suggested that axonal exposure and axoaxonal apposition are constant, significant features of pulpal nerve fibers that may be related to the onset and spread of nociceptive activity. The permeability properties of pulpal axons may differ from those of more centrally placed axons.

  10. 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

  11. Complications of third molar surgery and their management.

    PubMed

    Marciani, Robert D

    2012-09-01

    The frequency and severity of untoward events associated with surgical procedures are influenced by multiple factors that may be related to the procedure, patient, and/or surgeon. Not every third molar needs to be removed. Full bony impacted lower third molars well below the cervical margin of the second molar crowns should be considered for retention. Certain deviations from normal healing should be considered to be complications. Risk factors associated with third molar removal should be carefully established and explained to the patient. Third molar surgery has a predictable postsoperative course for the average patient.

  12. Complications of third molar surgery and their management.

    PubMed

    Marciani, Robert D

    2012-09-01

    The frequency and severity of untoward events associated with surgical procedures are influenced by multiple factors that may be related to the procedure, patient, and/or surgeon. Not every third molar needs to be removed. Full bony impacted lower third molars well below the cervical margin of the second molar crowns should be considered for retention. Certain deviations from normal healing should be considered to be complications. Risk factors associated with third molar removal should be carefully established and explained to the patient. Third molar surgery has a predictable postsoperative course for the average patient. PMID:23021398

  13. 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

  14. Third molar development: measurements versus scores as age predictor.

    PubMed

    Thevissen, P W; Fieuws, S; Willems, G

    2011-10-01

    Human third molar development is widely used to predict chronological age of sub adult individuals with unknown or doubted age. For these predictions, classically, the radiologically observed third molar growth and maturation is registered using a staging and related scoring technique. Measures of lengths and widths of the developing wisdom tooth and its adjacent second molar can be considered as an alternative registration. The aim of this study was to verify relations between mandibular third molar developmental stages or measurements of mandibular second molar and third molars and age. Age related performance of stages and measurements were compared to assess if measurements added information to age predictions from third molar formation stage. The sample was 340 orthopantomograms (170 females, 170 males) of individuals homogenously distributed in age between 7 and 24 years. Mandibular lower right, third and second molars, were staged following Gleiser and Hunt, length and width measurements were registered, and various ratios of these measurements were calculated. Univariable regression models with age as response and third molar stage, measurements and ratios of second and third molars as predictors, were considered. Multivariable regression models assessed if measurements or ratios added information to age prediction from third molar stage. Coefficients of determination (R(2)) and root mean squared errors (RMSE) obtained from all regression models were compared. The univariable regression model using stages as predictor yielded most accurate age predictions (males: R(2) 0.85, RMSE between 0.85 and 1.22 year; females: R(2) 0.77, RMSE between 1.19 and 2.11 year) compared to all models including measurements and ratios. The multivariable regression models indicated that measurements and ratios added no clinical relevant information to the age prediction from third molar stage. Ratios and measurements of second and third molars are less accurate age predictors

  15. Evaluating controlling factors to Al(i)/(Ca + Mg) molar ratio in acidic soil water, southern and southwestern China: multivariate approach.

    PubMed

    Guo, Jing-Heng; Zhang, Xiao-Shan; Vogt, Rolf D; Xiao, Jin-Song; Zhao, Da-Wei; Xiang, Ren-Jun; Luo, Jia-Hai

    2007-06-01

    Al(i)/(Ca + Mg) molar ratio in soil water has been used as an indicator to the effects of acid deposition on terrestrial ecosystems. However, the main factors controlling this ratio have not been well documented in southern and southwestern China. In this study, we presented the variation in inorganic aluminum (Al(i)) and Al(i)/(Ca + Mg) molar ratio in different sites and soil horizons based on two to three years monitoring data, and evaluated the main factors controlling Al(i)/(Ca + Mg) molar ratio using principle component analysis (PCA) and partial least square (PLS) regression. Monitoring data showed although Al(i)/(Ca + Mg) molar ratios in most soil water were lower than assumed critical 1.0, higher molar ratios were found in some soil water at TSP and LXH site. Besides acid loading, both soil properties and soil water chemistry affected the value of Al(i)/(Ca + Mg) molar ratio in soil water. Partial least square (PLS) indicated that they had different relative importance in different soil horizons. In A-horizon, soil aluminum saturation (AlS) had higher influence on Al(i)/(Ca + Mg) molar ratio than soil water chemistry did; higher soil aluminum saturation (AlS) led to higher Al(i)/(Ca + Mg) molar ratio in soil water. In the deeper horizons (i.e., B(1)-, B(2)- and BC-horizon), inorganic aluminum (Al(i)) in soil water had more and more important role in regulating Al(i)/(Ca + Mg) molar ratio. On regional scale, soil aluminum saturation (AlS) as well as cation exchange capacity (CEC) was the dominant factor controlling Al(i)/(Ca + Mg) molar ratio. This should be paid enough attention on when making regional acid rain control policy in China.

  16. Evaluating controlling factors to Al(i)/(Ca + Mg) molar ratio in acidic soil water, southern and southwestern China: multivariate approach.

    PubMed

    Guo, Jing-Heng; Zhang, Xiao-Shan; Vogt, Rolf D; Xiao, Jin-Song; Zhao, Da-Wei; Xiang, Ren-Jun; Luo, Jia-Hai

    2007-06-01

    Al(i)/(Ca + Mg) molar ratio in soil water has been used as an indicator to the effects of acid deposition on terrestrial ecosystems. However, the main factors controlling this ratio have not been well documented in southern and southwestern China. In this study, we presented the variation in inorganic aluminum (Al(i)) and Al(i)/(Ca + Mg) molar ratio in different sites and soil horizons based on two to three years monitoring data, and evaluated the main factors controlling Al(i)/(Ca + Mg) molar ratio using principle component analysis (PCA) and partial least square (PLS) regression. Monitoring data showed although Al(i)/(Ca + Mg) molar ratios in most soil water were lower than assumed critical 1.0, higher molar ratios were found in some soil water at TSP and LXH site. Besides acid loading, both soil properties and soil water chemistry affected the value of Al(i)/(Ca + Mg) molar ratio in soil water. Partial least square (PLS) indicated that they had different relative importance in different soil horizons. In A-horizon, soil aluminum saturation (AlS) had higher influence on Al(i)/(Ca + Mg) molar ratio than soil water chemistry did; higher soil aluminum saturation (AlS) led to higher Al(i)/(Ca + Mg) molar ratio in soil water. In the deeper horizons (i.e., B(1)-, B(2)- and BC-horizon), inorganic aluminum (Al(i)) in soil water had more and more important role in regulating Al(i)/(Ca + Mg) molar ratio. On regional scale, soil aluminum saturation (AlS) as well as cation exchange capacity (CEC) was the dominant factor controlling Al(i)/(Ca + Mg) molar ratio. This should be paid enough attention on when making regional acid rain control policy in China. PMID:17057971

  17. 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.

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

    PubMed Central

    Bersh, P J

    2001-01-01

    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

  19. Clinical significance of computed tomography assessment for third molar surgery.

    PubMed

    Nakamori, Kenji; Tomihara, Kei; Noguchi, Makoto

    2014-07-28

    Surgical extraction of the third molar is the most commonly performed surgical procedure in the clinical practice of oral surgery. Third molar surgery is warranted when there is inadequate space for eruption, malpositioning, or risk for cyst or odontogenic tumor formation. Preoperative assessment should include a detailed morphologic analysis of the third molar and its relationship to adjacent structures and surrounding tissues. Due to developments in medical engineering technology, computed tomography (CT) now plays a critical role in providing the clear images required for adequate assessment prior to third molar surgery. Removal of the maxillary third molar is associated with a risk for maxillary sinus perforation, whereas removal of the mandibular third molar can put patients at risk for a neurosensory deficit from damage to the lingual nerve or inferior alveolar nerve. Multiple factors, including demographic, anatomic, and treatment-related factors, influence the incidence of nerve injury during or following removal of the third molar. CT assessment of the third molar prior to surgery can identify some of these risk factors, such as the absence of cortication between the mandibular third molar and the inferior alveolar canal, prior to surgery to reduce the risk for nerve damage. This topic highlight presents an overview of the clinical significance of CT assessment in third molar surgery. PMID:25071882

  20. Clinical significance of computed tomography assessment for third molar surgery

    PubMed Central

    Nakamori, Kenji; Tomihara, Kei; Noguchi, Makoto

    2014-01-01

    Surgical extraction of the third molar is the most commonly performed surgical procedure in the clinical practice of oral surgery. Third molar surgery is warranted when there is inadequate space for eruption, malpositioning, or risk for cyst or odontogenic tumor formation. Preoperative assessment should include a detailed morphologic analysis of the third molar and its relationship to adjacent structures and surrounding tissues. Due to developments in medical engineering technology, computed tomography (CT) now plays a critical role in providing the clear images required for adequate assessment prior to third molar surgery. Removal of the maxillary third molar is associated with a risk for maxillary sinus perforation, whereas removal of the mandibular third molar can put patients at risk for a neurosensory deficit from damage to the lingual nerve or inferior alveolar nerve. Multiple factors, including demographic, anatomic, and treatment-related factors, influence the incidence of nerve injury during or following removal of the third molar. CT assessment of the third molar prior to surgery can identify some of these risk factors, such as the absence of cortication between the mandibular third molar and the inferior alveolar canal, prior to surgery to reduce the risk for nerve damage. This topic highlight presents an overview of the clinical significance of CT assessment in third molar surgery. PMID:25071882

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

    PubMed Central

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

    2012-01-01

    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

  2. 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

  3. The predictivity of mandibular third molar position as a risk indicator for pericoronitis.

    PubMed

    Yamalik, Kemal; Bozkaya, Süleyman

    2008-03-01

    The aim of this study was to describe the characteristics of the mandibular third molar at highest risk for acute pericoronitis using clinical and radiographic analysis. A total of 102 volunteers, including 40 (39%) male and 62 (60%) female patients presenting with acute pericoronitis, participated in the study. The mean age of the participants was 23.4 years (range 17-30 years). The variables tested included the percentage of soft tissue coverage, availability of impinging maxillary dentition, and the angulation and eruption level of the mandibular third molar. While vertical impaction was the most frequent angulation (51%), horizontal impaction was quite rare (3%). Mesioangular impaction (25%) was slightly higher than distoangular impaction (21%). Difference between type of angulation was statistically significant for all groups (p < 0.05). The frequency of partial soft tissue coverage, particularly 75% coverage, was far more observed than the full soft tissue coverage (47%). The difference for the amount of soft tissue coverage was statistically significant (p < 0.05). In 57% of the cases, pericoronitis was associated with the third molars that erupted at the same level of the adjacent tooth occlusal plane. The difference among the three levels of eruption was significant (p < 0.000). Impinging maxillary dentition did not have a significant impact on development of pericoronitis (41%). Evidence of impinging maxillary dentition did not have a statistically significant impact on presence of pericoronitis (p = 0.075). Mandibular third molars at or near to the same level of the occlusal plane of the arch and exhibiting vertical inclination were considered at highest risk for developing pericoronitis. Such third molars can be given high priority for prophylactic care due to the possibility of severe consequences of acute pericoronitis.

  4. 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

  5. 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.

  6. Characterization of branched ultrahigh molar mass polymers by asymmetrical flow field-flow fractionation and size exclusion chromatography.

    PubMed

    Otte, T; Pasch, H; Macko, T; Brüll, R; Stadler, F J; Kaschta, J; Becker, F; Buback, M

    2011-07-01

    The molar mass distribution (MMD) of synthetic polymers is frequently analyzed by size exclusion chromatography (SEC) coupled to multi angle light scattering (MALS) detection. For ultrahigh molar mass (UHM) or branched polymers this method is not sufficient, because shear degradation and abnormal elution effects falsify the calculated molar mass distribution and information on branching. High temperatures above 130 °C have to be applied for dissolution and separation of semi-crystalline materials like polyolefins which requires special hardware setups. Asymmetrical flow field-flow fractionation (AF4) offers the possibility to overcome some of the main problems of SEC due to the absence of an obstructing porous stationary phase. The SEC-separation mainly depends on the pore size distribution of the used column set. The analyte molecules can enter the pores of the stationary phase in dependence on their hydrodynamic volume. The archived separation is a result of the retention time of the analyte species inside SEC-column which depends on the accessibility of the pores, the residence time inside the pores and the diffusion ability of the analyte molecules. The elution order in SEC is typically from low to high hydrodynamic volume. On the contrary AF4 separates according to the diffusion coefficient of the analyte molecules as long as the chosen conditions support the normal FFF-separation mechanism. The separation takes place in an empty channel and is caused by a cross-flow field perpendicular to the solvent flow. The analyte molecules will arrange in different channel heights depending on the diffusion coefficients. The parabolic-shaped flow profile inside the channel leads to different elution velocities. The species with low hydrodynamic volume will elute first while the species with high hydrodynamic volume elute later. The AF4 can be performed at ambient or high temperature (AT-/HT-AF4). We have analyzed one low molar mass polyethylene sample and a number of

  7. Autotransplantation of a Buccally Erupted Matured Mandibular Third Molar to Replace a Grossly Decayed Second Molar

    PubMed Central

    Bodh, Ranjeet; Kaushik, Aishvarya; Talwar, Sangeeta

    2016-01-01

    Autotransplantation can be a treatment option for tooth loss as an alternative to fixed or implant-supported prostheses. It has predictable results comparable to implants, with reported success rates often greater than 90%. In present case, buccally erupted matured third molar was autotransplanted in extraction socket of grossly carious mandibular second molar. The tooth was splinted for 1 week followed by root canal treatment. After 12 months follow up, tooth was in perfect state of function and aesthetic with healthy periapical and periodontal architecture. High success rate was found in immature tooth transplantation in previous case reports. This case report describes that even matured tooth can also be used as donor if atraumatic extraction is possible and endodontic treatment is well performed. PMID:27042593

  8. [Distalization of the upper second molar: clinical case].

    PubMed

    Castaldo, A; Blasi, S; Vettese, P

    1991-01-01

    The Authors showed a clinical case in which has been put on a distalizing system together with a palatal bar between the first upper molars, a sectional placed between the first and the second molar and a 100 g precalibrated Sentalloy coil. PMID:1784297

  9. Early prediction of mandibular third molar eruption/impaction using linear and angular measurements on digital panoramic radiography: A radiographic study

    PubMed Central

    Kaur, Rachninder; Kumar, Anand C.; Garg, Ranjana; Sharma, Sugandha; Rastogi, Trisha; Gupta, Vivek Vijay

    2016-01-01

    Background: The impaction rate is higher for the third molars than for any other tooth in modern human population. This study was conducted with the aim to evaluate the validity of linear and angular measurements on the digital panoramic radiograph as a reference for early prediction of mandibular third molar eruption/impaction. Materials and Methods: Digital panoramic radiographs of 200 subjects were selected based on their status of eruption of mandibular third molars; fully erupted (Group A), partially erupted (Group B), fully developed but not erupted (Group C) and partially developed groups (Group D). Each group comprised 50 subjects with 25 males and 25 females. Nine variables (linear measurements, angles, and ratios) were determined and measured bilaterally by two observers and values were compared between the study groups and genders. Results: The data thus obtained were analyzed for comparison among all the study groups. It was found that the difference in the mean values of lower eruption space (LES) measurements, α-angle (angle between long axis of the third molar and gonial-symphyseal plane) and β-angle (angle between long axis of mandibular second and third molars) were significant (P < 0.05). The mean values of mesiodistal width, LES-ramus, LES-Xi point and β-angle were found more in males than in females. No significant difference was observed between the sides. Conclusion: α- and β-angle together with LES measurements give the accurate information on early prediction of lower third molar eruption or impaction. PMID:27433048

  10. 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

  11. Hydatidiform molar pregnancy in Malaysian women: a histopathological study from the University Hospital, Kuala Lumpur.

    PubMed

    Cheah, P L; Looi, L M; Sivanesaratnam, V

    1993-06-01

    A review of gestational trophoblastic disease diagnosed at the Department of Pathology, University Hospital, Kuala Lumpur from January 1989 to December 1990 using established histological criteria showed 25 complete hydatidiform moles (CHM), 11 partial hydatidiform moles (PHM), 1 invasive mole and 2 choriocarcinoma. The ages of the patients with CHM ranged from 21 to 43 years (mean = 28.5 years) and PHM 20 to 33 years (mean = 27.5 years). The invasive mole occurred in a 42-year-old Malay woman. The two patients with choriocarcinoma were both Chinese and 41 and 46-years old respectively. During the same period, 1,062 non-molar abortions and 13,115 births, inclusive of livebirths and stillbirths were recorded at the University Hospital. The incidence rate of hydatidiform moles was thus estimated to be 1:384 pregnancies. PHM constituted 30% of all molar pregnancies. Hydatidiform moles occurred among the Malays, Chinese and Indians at the rate of 2.43, 2.66 and 3.29 per 1,000 pregnancies respectively. It appears that hydatidiform molar pregnancy has the highest prevalence among the Indians, a finding similar to an earlier Singapore study.

  12. Molecular Volumes and the Stokes-Einstein Equation

    ERIC Educational Resources Information Center

    Edward, John T.

    1970-01-01

    Examines the limitations of the Stokes-Einstein equation as it applies to small solute molecules. Discusses molecular volume determinations by atomic increments, molecular models, molar volumes of solids and liquids, and molal volumes. Presents an empirical correction factor for the equation which applies to molecular radii as small as 2 angstrom…

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

    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 25°C is determined via isothermal saturation. The kinematic viscosity of a mixture of methanol-octane-naphthalene is measured at 25°C. 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.

  14. Occlusal molar surfaces in females with Turner's syndrome.

    PubMed

    Maćesić, Mihajlo; Kaić, Zvonimir; Dumancić, Jelena; Poje, Zvonko; Dumić, Miroslav

    2003-12-01

    The aim of this study was to identify the molar occlusal features in 73 subjects with the Turner's syndrome (TS) and compared to a control group (CG) of 322 healthy females. The occlusal features were scored on dental plaster casts using the Scoring Procedures for Key Morphological Traits of the Permanent Dentition: The Arizona State University Dental Anthropology System (ASU). The results were analyzed through frequency, percentage and chi 2-test. TS subjects have more frequent reduction of cusp number, distolingual cusp on the upper molars and distal cusp on the lower molar, with the consequent reduction of the occlusal surface. Reduced size of occlusal surface and number cusps on upper molars resulted in the transformation of rhomboid occlusal shape into triangular, with the consequent loss of H-shaped groove system (in the upper right first molars H-shaped groove system was significantly less frequently found in TS (p < 0.05); in the upper left second molars H-shaped groove system was significantly less frequently found in TS (p < 0.01). The X-chromosome aneuploidy can cause a decrease in developmental homeostasis, which results in the alteration of apposition of the enamel and in consequently substantial changes of the molar occlusal morphological features.

  15. Human third molars development: Comparison of 9 country specific populations.

    PubMed

    Thevissen, P W; Fieuws, S; Willems, G

    2010-09-10

    The majority of age estimation models based on third molar development are constructed on samples from populations with described and outlined origin. Due to unlike research protocols these studies can rarely be compared for the evaluation of possible geographical or ethnical influences on third molar development. The aim of this study is to evaluate country specific third molar development on standardized collected and analyzed data. On panoramic radiographs selected from subjects out of 9 country specific populations (Belgium, China, Japan, Korea, Poland, Thailand, Turkey, Saudi-Arabia and South-India) the four third molar scores were registered, according to a modified Gleiser and Hunt methodology. To obtain for each subject a (factor) score which represents the degree of third molar development, a generalized linear mixed model for multivariate ordinal data was fitted on the repeated third molar scores. Differences between countries are analyzed using gender-specific regression models for these factor scores with age and country as predictors. Comparisons between countries revealed differences in speed and onset of development. However, although reaching statistical significance, differences in actual value were small and not constant over the considered age range. In all countries, at all ages, males were ahead in third molar development compared to females.

  16. 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

  17. 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 12 h and 1, 2, 3, 5 and 7 days 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 6-12 h after irradiation, the odontoblastic layer was disorganized and some of odontoblasts lost the immunoreactivity to HSP-25 and nestin. At 1-2 days, 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 3-7 days. BrdU-positive cells showed a significant increase at 2 days (P < 0.05 vs. immediate previous time point; one-way analysis of variance and Scheffé post hoc test), peaked at 3 days 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.

  18. Adapting molar data (without density) for molal models

    NASA Astrophysics Data System (ADS)

    Marion, Giles M.

    2007-06-01

    Theoretical geochemical models for electrolyte solutions based on classical thermodynamic principles rely largely upon molal concentrations as input because molality (wt/wt) is independent of temperature and pressure. On the other hand, there are countless studies in the literature where concentrations are expressed as molarity (wt/vol) because these units are more easily measured. To convert from molarity to molality requires an estimate of solution density. Unfortunately, in many, if not most, cases where molarity is the concentration of choice, solution densities are not measured. For concentrated brines such as seawater or even more dense brines, the difference between molarity and molality is significant. Without knowledge of density, these brinish, molar-based studies are closed to theoretical electrolyte solution models. The objective of this paper is to present an algorithm that can accurately calculate the density of molar-based solutions, and, as a consequence, molality. The algorithm consist of molar inputs into a molal-based model that can calculate density (FREZCHEM). The algorithm uses an iterative process for calculating absolute salinity (SA), density (ρ), and the conversion factor (CF) for molarity to molality. Three cases were examined ranging in density from 1.023 to 1.203 kg(soln.)/l. In all three cases, the SA, ρ, and CF values converged to within 1ppm by nine iterations. In all three cases, the calculated densities agreed with experimental measurements to within ±0.1%. This algorithm opens a large literature based on molar concentrations to exploration with theoretical models based on molal concentrations and classical thermodynamic principles.

  19. Partial oxidation catalyst

    DOEpatents

    Krumpelt, Michael; Ahmed, Shabbir; Kumar, Romesh; Doshi, Rajiv

    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.

  20. Modification of uprighting spring for derotation of second molars.

    PubMed

    Mallikarjun, Vankre; Rachala, Madhukar Reddy; Aileni, Kaladhar Reddy; Jaipal, Pyata Reddy

    2013-01-01

    One of the most efficient ways for the correction of rotated upper molars is derotation with a transpalatal arch, but this appliance is usually favourable when the need for correction is same on both sides of the dental arch. Derotation of unilateral upper second molar is a difficult task, especially when there is no accessible tooth/ any attachment is available distal to it for the application of couple forces. We have designed a modification of uprighting spring which is far more convenient than using the conventional method of TPA for derotation of unilateral upper second molar. PMID:24640073

  1. 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

  2. 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.

  3. Volumetric Measurement of Root Resorption following Molar Mini-Screw Implant Intrusion Using Cone Beam Computed Tomography

    PubMed Central

    Li, Wen; Chen, Fei; Zhang, Feng; Ding, Wanghui; Ye, Qingsong; Shi, Jiejun; Fu, Baiping

    2013-01-01

    Objective Molar intrusion by mini-screw implantation can cause different degrees of root resorption. However, most methods (2-D and 3-D) used for evaluating root resorption have focused on the root length without considering 3-D resorption. The purpose of this study was to volumetrically evaluate root resorption using cone beam computed tomography(CBCT) after mini-screw implant intrusion. Materials and Methods 1. The volumes of 32 teeth were measured using CBCT and laser scanning to verify the accuracy of CBCT. 2. Twelve overerupted molars from adult patients were investigated in this study. After mini-screw implants were inserted into the buccal and palatal alveolar bones, 150 g of force was applied to the mini-screw implants on each side to intrude the molars. CBCT images of all patients were taken immediately prior to intrusion and after intrusion. The volumes of the roots were calculated using the Mimics software program. The differences between the pre-intrusion and post-intrusion root volumes were statistically evaluated with a paired-samples t-test. In addition, the losses of the roots were statistically compared with each other using one-way analysis of variance at the P<0.05 level. Results No statistically significant volume differences were observed between the physical (laser scanning) and CBCT measurements (P>0.05). The overerupted molars were significantly intruded (P<0.05), and the average intrusion was 3.30±1.60 mm. The differences between the pre-intrusion and post-intrusion root volumes were statistically significant for all of the roots investigated (P<0.05). The roots were sorted by volume loss in descending order as follows: mesiobuccal, palatal, and distobuccal. Statistical significance was achieved among the three roots. The average total resorption for each tooth was 58.39±1.54 mm3. Conclusion Volume measurement using CBCT was able to effectively evaluate root resorption caused by mini-screw intrusion. The highest volume loss was observed

  4. Exploring volume, compressibility and hydration changes of folded proteins upon compression.

    PubMed

    Voloshin, Vladimir P; Medvedev, Nikolai N; Smolin, Nikolai; Geiger, Alfons; Winter, Roland

    2015-04-01

    Understanding the physical basis of the structure, stability and function of proteins in solution, including extreme environmental conditions, requires knowledge of their temperature and pressure dependent volumetric properties. One physical-chemical property of proteins that is still little understood is their partial molar volume and its dependence on temperature and pressure. We used molecular dynamics simulations of aqueous solutions of a typical monomeric folded protein, staphylococcal nuclease (SNase), to study and analyze the pressure dependence of the apparent volume, Vapp, and its components by the Voronoi-Delaunay method. We show that the strong decrease of Vapp with pressure (βT = 0.95 × 10(-5) bar(-1), in very good agreement with the experimental value) is essentially due to the compression of the molecular volume, VM, ultimately, of its internal voids, V. Changes of the intrinsic volume (defined as the Voronoi volume of the molecule), the contribution of the solvent to the apparent volume, and of the contribution of the boundary voids between the protein and the solvent have also been studied and quantified in detail. The pressure dependences of the volumetric characteristics obtained are compared with the temperature dependent behavior of these quantities and with corresponding results for a natively unfolded polypeptide. PMID:25685984

  5. A three-dimensional finite element analysis of molar distalization with a palatal plate, pendulum, and headgear according to molar eruption stage

    PubMed Central

    Kang, Ju-Man; Park, Jae Hyun; Bayome, Mohamed; Oh, Moonbee; Park, Chong Ook; Mo, Sung-Seo

    2016-01-01

    Objective This study aimed to (1) evaluate the effects of maxillary second and third molar eruption status on the distalization of first molars with a modified palatal anchorage plate (MPAP), and (2) compare the results to the outcomes of the use of a pendulum and that of a headgear using three-dimensional finite element analysis. Methods Three eruption stages were established: an erupting second molar at the cervical one-third of the first molar root (Stage 1), a fully erupted second molar (Stage 2), and an erupting third molar at the cervical one-third of the second molar root (Stage 3). Retraction forces were applied via three anchorage appliance models: an MPAP with bracket and archwire, a bone-anchored pendulum appliance, and cervical-pull headgear. Results An MPAP showed greater root movement of the first molar than crown movement, and this was more noticeable in Stages 2 and 3. With the other devices, the first molar showed distal tipping. Transversely, the first molar had mesial-out rotation with headgear and mesial-in rotation with the other devices. Vertically, the first molar was intruded with an MPAP, and extruded with the other appliances. Conclusions The second molar eruption stage had an effect on molar distalization, but the third molar follicle had no effect. The application of an MPAP may be an effective treatment option for maxillary molar distalization. PMID:27668192

  6. A three-dimensional finite element analysis of molar distalization with a palatal plate, pendulum, and headgear according to molar eruption stage

    PubMed Central

    Kang, Ju-Man; Park, Jae Hyun; Bayome, Mohamed; Oh, Moonbee; Park, Chong Ook; Mo, Sung-Seo

    2016-01-01

    Objective This study aimed to (1) evaluate the effects of maxillary second and third molar eruption status on the distalization of first molars with a modified palatal anchorage plate (MPAP), and (2) compare the results to the outcomes of the use of a pendulum and that of a headgear using three-dimensional finite element analysis. Methods Three eruption stages were established: an erupting second molar at the cervical one-third of the first molar root (Stage 1), a fully erupted second molar (Stage 2), and an erupting third molar at the cervical one-third of the second molar root (Stage 3). Retraction forces were applied via three anchorage appliance models: an MPAP with bracket and archwire, a bone-anchored pendulum appliance, and cervical-pull headgear. Results An MPAP showed greater root movement of the first molar than crown movement, and this was more noticeable in Stages 2 and 3. With the other devices, the first molar showed distal tipping. Transversely, the first molar had mesial-out rotation with headgear and mesial-in rotation with the other devices. Vertically, the first molar was intruded with an MPAP, and extruded with the other appliances. Conclusions The second molar eruption stage had an effect on molar distalization, but the third molar follicle had no effect. The application of an MPAP may be an effective treatment option for maxillary molar distalization.

  7. 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

  8. Cementoblastoma Relating to Right Mandibular Second Primary Molar

    PubMed Central

    Manepalli, Swapna; Mohapatra, Abinash

    2016-01-01

    Cementoblastoma is a benign lesion of the odontogenic ectomesenchymal origin. It rarely occurs in primary dentition. This report describes a case of a cementoblastoma relating to the right mandibular second primary molar in a 7-year-old girl. Her panoramic radiograph revealed a well-defined radiopaque lesion with a radiolucent border extending from the distal surface of the mandibular right first primary molar to the distal surface of mandibular second primary molar. The tumor was attached to the mesial root of primary second molar and was excised along with the teeth involved and sent for histopathological evaluation, which showed irregular trabeculae of mineralized tissue interspersed with fibrovascular connective tissue, trabeculae of mineralized tissue with prominent reversal lines, and peripheral rimming of the mineralized tissue with blast cells. On a six-month follow-up, there has been no recurrence of the lesion. PMID:27738532

  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. The Tucker technique: conservative molar inlays preserving the transverse ridge.

    PubMed

    Hess, T A; Wadhwani, C P K

    2012-01-01

    Conservation of healthy tooth structure should be the aim of any restorative procedure. Two inlays may be an ideal choice for the treatment of maxillary molars to preserve the transverse ridge and maintain structural integrity.

  11. 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.

  12. 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

  13. Fusion or gemination? An unusual mandibular second molar

    PubMed Central

    Camargo, Angela Jordão; Arita, Emiko Saito; Watanabe, Plauto Christopher Aranha

    2015-01-01

    Fusion and gemination is not an uncommon finding and affected most primary dentition and the permanent maxillary incisors. These changes can develop a series of complication. A 11-year-old male presented radiography finding: an unusual mandibular second molar. A well-documented case brings a challenge for radiologists classify between fusion and gemination. In conclusion, this alteration although common in other regions, there are no case in the literature involving “second and third” molar. PMID:26945485

  14. Potential of human serum albumin as chiral selector of basic drugs in affinity electrokinetic chromatography-partial filling technique.

    PubMed

    Martínez-Gómez, Maria A; Villanueva-Camañas, R M; Sagrado, Salvador; Medina-Hernández, Maria J

    2006-11-01

    The enantiomeric resolution of compounds using HSA by means of affinity EKC (AEKC)-partial filling technique is the result of a delicate balance between different experimental variables such as protein concentration, running pH (background electrophoretic buffer (BGE), protein, and compound solutions), and plug length. In this paper, the possibility of using HSA as chiral selector for enantioseparation of 28 basic drugs using this methodology is studied. The effect of the physicochemical parameters, the structural properties of compounds, and compound-HSA protein binding percentages over their chiral resolution with HSA is outlined. Based on the results obtained, a decision tree is proposed for the "a priori" prediction of the capability of HSA for enantioseparation of basic drugs in AEKC. The results obtained indicated that enantioresolution of basic compounds with HSA depends on the hydrophobicity, polarity, and molar volume of compounds.

  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. Finite Element Reconstruction of a Mandibular First Molar

    PubMed Central

    Ehsani, Sara; Mirhashemi, Fatemeh Sadat; Asgary, Saeed

    2013-01-01

    Introduction Mandibular first molar is the most important tooth with complicated morphology. In finite element (FE) studies, investigators usually prefer to model anterior teeth with a simple and single straight root; it makes the results deviate from the actual case. The most complicated and time-consuming step in FE studies is modeling of the desired tooth, thus this study was performed to establish a finite element method (FEM) of reconstructing a mandibular first molar with the greatest precision. Materials and Methods An extracted mandibular first molar was digitized, and then radiographed from different aspects to achieve its outer and inner morphology. The solid model of tooth and root canals were constructed according to this data as well as the anatomy of mandibular first molar described in the literature. Result A three-dimensional model of mandibular first molar was created, giving special consideration to shape and root canal system dimensions. Conclusion This model may constitute a basis for investigating the effect of different clinical situations on mandibular first molars in vitro, especially on its root canal system. The method described here seems feasible and reasonably precise foundation for investigations. PMID:23717327

  17. 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

  18. Impacted third molars and risk of angle fracture.

    PubMed

    Meisami, T; Sojat, A; Sàndor, G K B; Lawrence, H P; Clokie, C M L

    2002-04-01

    The purpose of this study was to assess the influence of the presence, position, and severity of impaction of the mandibular third molars, on the incidence of mandibular angle fractures. A retrospective cohort study was designed for patients presenting to the Division of Oral and Maxillofacial Surgery, Toronto General Hospital (Toronto, Canada), for treatment of mandibular fractures from January 1995 to June 2000. The independent variables in this study were the presence, position and severity of impaction of third molars. The outcome variable was the incidence of mandibular angle fractures. Hospital charts and panoramic radiographs were used to determine and classify these variables. The demographic data included age, sex, mechanism of injury and number of mandibular fractures. The study sample comprised 413 mandibular fractures in 214 patients. The incidence of angle fractures was found to be significantly higher in the male population and was most commonly seen in the third decade of life. Assault remained the most significant aetiological factor. Patients with third molars had thrice the increased risk of angle fractures when compared to patients without (P<0.001). Impaction of third molars significantly increased the incidence of angle fractures (P<0.001). The severity and angulation of third molar impactions were not significantly associated with angle fractures. This study provides evidence that patients with retained impacted third molars are significantly more susceptible to angle fracture than those without. The risk for angle fracture, however, does not seem to be influenced by the severity of impaction.

  19. 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

  20. Main occluding area in partially edentulous patients: changes before and after implant treatment.

    PubMed

    Goto, T; Nishinaka, H; Kashiwabara, T; Nagao, K; Ichikawa, T

    2012-09-01

    The 'main occluding area', the location where food crushing occurs during the first stroke of mastication, is reported to be an important concept; however, it is currently limited to findings in individuals with normal dentition. The purpose of this study was to assess the changes in the location, area and bite force of the main occluding area before and after implant treatments. We enrolled 50 partially edentulous and 22 normally dentate subjects. To identify the location of the main occluding area, each subject was instructed to freely bite once on a dental stopping using the partially edentulous side or the normally dentate area. The location, occluding contact area and bite force of the main occluding area before and after the implant treatments were analysed. The main occluding area was located at a reproducible location in the partially edentulous and normally dentate subjects. This location was principally the first molar region, and for the partially edentulous patients with missing teeth in the molar regions, it moved from the premolar region to the first molar region after treatment. The occluding contact area and bite force for the main occluding area increased (P < 0·05) after the implant treatment in the partially edentulous patients with missing teeth in the molar regions. These results suggest that the main occluding area can be restored to the first molar region after implant treatment and may be an important factor in the assessment of prosthodontic treatment. PMID:22672204

  1. Radiographic evaluation of bone regeneration after the application of plasma rich in growth factors in a lower third molar socket: a case report

    PubMed Central

    2009-01-01

    A 42-year-old Mediterranean male presented complaining of inability to sustain good oral care at the posterior aspect of the lower right jaw. The main problems were food impaction in the area and the subsequent malodor. The patient reported remarkable medical history. Clinical examination revealed local erytherma with noticeable bone defect distal to the second molar with obvious defect in the mesial wall of the third molar; the penetration depth was found to be up to 6 mm. Radiological evaluation confirmed the defect and it was attributed to the mesioangularly partially impacted lower third molar. It was decided that third molar should be extracted and concentrate of the patient's growth factors (PRGF) to be applied into the bony defect to stimulate bone regeneration and promote healing. The third molar tooth was, then, removed surgically and the PRGF, which was prepared preoperatively, was implanted in the socket. At the first postoperative day, moderate pain was the main complaint and was controlled by NSAIDs. One week postoperatively, the sutures were removed and there was good tissue healing on examination. On the fiftieth postoperative day, radiographic evaluation took place and showed noticeable enhancement of density and radio-opacity in the third molar socket area, in comparison with the baseline image. Further, clinical examination showed significant reduction of periodontal pocketing and evidence of new bone formation. In conclusion, PRGF was very successful in stimulating bone regeneration and promote healing following dental extraction. PMID:20062651

  2. Radiographic evaluation of bone regeneration after the application of plasma rich in growth factors in a lower third molar socket: a case report.

    PubMed

    Nazaroglou, Ioannis; Stavrianos, Christos; Kafas, Panagiotis; Matoulas, Euthimios; Upile, Tahwinder; Barlas, Irodis; Jerjes, Waseem

    2009-12-03

    A 42-year-old Mediterranean male presented complaining of inability to sustain good oral care at the posterior aspect of the lower right jaw. The main problems were food impaction in the area and the subsequent malodor. The patient reported remarkable medical history. Clinical examination revealed local erytherma with noticeable bone defect distal to the second molar with obvious defect in the mesial wall of the third molar; the penetration depth was found to be up to 6 mm.Radiological evaluation confirmed the defect and it was attributed to the mesioangularly partially impacted lower third molar. It was decided that third molar should be extracted and concentrate of the patient's growth factors (PRGF) to be applied into the bony defect to stimulate bone regeneration and promote healing.The third molar tooth was, then, removed surgically and the PRGF, which was prepared preoperatively, was implanted in the socket. At the first postoperative day, moderate pain was the main complaint and was controlled by NSAIDs. One week postoperatively, the sutures were removed and there was good tissue healing on examination.On the fiftieth postoperative day, radiographic evaluation took place and showed noticeable enhancement of density and radio-opacity in the third molar socket area, in comparison with the baseline image. Further, clinical examination showed significant reduction of periodontal pocketing and evidence of new bone formation.In conclusion, PRGF was very successful in stimulating bone regeneration and promote healing following dental extraction.

  3. Efficacy and Safety of 2% and 4% Articaine for Lower Third Molar Surgery.

    PubMed

    Senes, A M; Calvo, A M; Colombini-Ishikiriama, B L; Gonçalves, P Z; Dionísio, T J; Sant'ana, E; Brozoski, D T; Lauris, J R P; Faria, F A C; Santos, C F

    2015-09-01

    This double-blind crossover randomized clinical trial compared the efficacy of 2 concentrations of articaine, 2% (A2) and 4% (A4), with 1:200,000 epinephrine, for lower third molar removal. During 2 separate appointments with either A2 or A4, both similarly positioned lower third molars in 46 volunteers were extracted. The following were evaluated: onset and duration of anesthetic action on soft tissues, intraoperative bleeding, hemodynamic parameters, postoperative analgesia, and mouth opening and wound healing during the 7th postoperative day, along with the incidence, type, and severity of adverse reactions. Nearly identical volumes of both anesthetic solutions were used for each appointment: 3.4 ± 0.9 mL ≈ 68 mg of articaine (A2) and 3.3 ± 0.8 mL ≈ 132 mg of articaine (A4). Statistical analysis indicated no differences in onset or duration of anesthetic action on soft tissues or duration of postoperative analgesia evoked by A2 and A4 anesthetic solutions (P > 0.05). The surgeon's rating of intraoperative bleeding was considered minimal throughout all surgery with both anesthetic solutions. While transient changes in blood pressure, heart rate, and oxygen saturation were observed, these factors were clinically insignificant and were uninfluenced by articaine concentration (P > 0.05). No systemic or local adverse reactions were observed in the preoperative and postoperative periods due to A2 or A4, but 1 case of bilateral paresthesia was observed. There were no significant differences between preoperative and postoperative (7th day) values of mouth opening and wound healing whether volunteers received A2 or A4 (P > 0.05). In conclusion, both A2 and A4, administered in equal volumes, were effective and safe during lower third molar surgery, and no significant differences were found between their efficacy and safety (ClinicalTrials.gov NCT02457325). PMID:26202994

  4. Variation in Cuspal Morphology in Maxillary First Permanent Molar with Report of 3 Cusp Molar- A Prevalence Study

    PubMed Central

    2016-01-01

    Introduction Human teeth has always been known for morphological variations in both the crown and root structures. The corono-morphological variations can be in the form of extra cusp or missing cusp. Permanent maxillary first molars are the biggest teeth in maxillary arch and have a high anchorage value and are known for their four cusp and five cusp patterns, if present with cusp of Carebelli. Aim The aim of this study was to determine the prevalence of cuspal variations and quantification of cusps of permanent maxillary first molar in Malwa population. Materials and Methods A total of 1249 individuals were studied at Government College of Dentistry, Indore, Madhya Pradesh, India, to evaluate the number of cusps in permanent maxillary first molars. Results Of the studied 1249 individuals, permanent maxillary first molars had five cusps in 407 (32.6%) cases while 838 (67.08%) cases had four cusp and four (0.32%) cases had three cusps. The four cases having three cusp permanent maxillary first molars were present unilaterally and only in females. Conclusion This article emphasizes the presence of permanent maxillary first molar with only three cusps in the Malwa population of India. It also reviews the literature in respect to this rare anomaly and calls for continuous and close monitoring to report such cases in the future. PMID:27790576

  5. Erupted complex odontoma delayed eruption of permanent molar.

    PubMed

    Ohtawa, Yumi; Ichinohe, Saori; Kimura, Eri; Hashimoto, Sadamitsu

    2013-01-01

    Odontomas, benign tumors that develop in the jaw, rarely erupt into the oral cavity. We report an erupted odontoma which delayed eruption of the first molar. The patient was a 10-year-old Japanese girl who came to our hospital due to delayed eruption of the right maxillary first molar. All the deciduous teeth had been shed. The second premolar on the right side had erupted, but not the first molar. Slight inflammation of the alveolar mucosa around the first molar had exposed a tooth-like, hard tissue. Panoramic radiography revealed a radiopaque mass indicating a lesion approximately 1 cm in diameter. The border of the image was clear, and part of the mass was situated close to the occlusal surface of the first molar. The root of the maxillary right first molar was only half-developed. A clinical diagnosis of odontoma was made. The odontoma was subsequently extracted, allowing the crown of the first molar to erupt almost 5 months later. The dental germ of the permanent tooth had been displaced by the odontoma. However, after the odontoma had been extracted, the permanent tooth was still able to erupt spontaneously, as eruptive force still remained. When the eruption of a tooth is significantly delayed, we believe that it is necessary to examine the area radiographically. If there is any radiographic evidence of a physical obstruction that might delay eruption, that obstruction should be removed before any problems can arise. Regular dental checkups at schools might improve our ability to detect evidence of delayed eruption earlier.

  6. First molar health status in different craniofacial relationships

    PubMed Central

    Linjawi, Amal I

    2016-01-01

    Objective To investigate the association between the health status of permanent first molars and different craniofacial relationships among adolescents. Study design This is a retrospective study on patients’ records aged 11–15 years. Sex, skeletal relationship, vertical growth pattern, malocclusion, overjet, and overbite were assessed. The health status of permanent first molars was recorded from the orthopantomograms and intraoral photographs as “sound” and “not sound”. Chi-square, Mann–Whitney U and Kruskal–Wallis tests, and Pearson’s correlation coefficient were used to analyze and correlate the assessed variables. Significance level was set at P<0.05. Results A total of 210 records were evaluated; 81 were male, 68 had Class I and 91 had Class II skeletal relationships. More than half of the subjects had normal (n=67) to moderate deep bite (n=72); normal (n=91), moderately increased (n=54), to severely increased (n=50) overjet; and Class I (n=106) and Class II division 1 (n=75) malocclusion. Significant differences were found in the health status of the permanent first molars with respect to sex (P=0.034), vertical growth pattern (P=0.01), and overbite (P=0.047). Strong correlations were only found between the health status of the permanent first molars and the following variables: sex (P=0.036) and vertical growth pattern (P=0.004). Significant correlation was further found between the upper left first molar health status and sex (P=0.019) and the lower right first molar health status and the vertical growth pattern (P=0.001). No significant association was found with the anteroposterior craniofacial relationships (P>0.05). Conclusion Sex difference and vertical growth patterns were found to be potential predictors of the health status of the permanent first molars. No significant association was found with the anteroposterior craniofacial relationships. PMID:27462176

  7. 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

  8. Erupted complex odontoma delayed eruption of permanent molar.

    PubMed

    Ohtawa, Yumi; Ichinohe, Saori; Kimura, Eri; Hashimoto, Sadamitsu

    2013-01-01

    Odontomas, benign tumors that develop in the jaw, rarely erupt into the oral cavity. We report an erupted odontoma which delayed eruption of the first molar. The patient was a 10-year-old Japanese girl who came to our hospital due to delayed eruption of the right maxillary first molar. All the deciduous teeth had been shed. The second premolar on the right side had erupted, but not the first molar. Slight inflammation of the alveolar mucosa around the first molar had exposed a tooth-like, hard tissue. Panoramic radiography revealed a radiopaque mass indicating a lesion approximately 1 cm in diameter. The border of the image was clear, and part of the mass was situated close to the occlusal surface of the first molar. The root of the maxillary right first molar was only half-developed. A clinical diagnosis of odontoma was made. The odontoma was subsequently extracted, allowing the crown of the first molar to erupt almost 5 months later. The dental germ of the permanent tooth had been displaced by the odontoma. However, after the odontoma had been extracted, the permanent tooth was still able to erupt spontaneously, as eruptive force still remained. When the eruption of a tooth is significantly delayed, we believe that it is necessary to examine the area radiographically. If there is any radiographic evidence of a physical obstruction that might delay eruption, that obstruction should be removed before any problems can arise. Regular dental checkups at schools might improve our ability to detect evidence of delayed eruption earlier. PMID:24521551

  9. 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.

  10. Parenteral monofluorophosphate (MFP) is a more potent inducer of enamel fluorotic defects in neonatal hamster molars than sodium fluoride.

    PubMed

    Lyaruu, Donacian M; Schoonderwoerd, Mark; Tio, Dane; Tse, Chukan; Bervoets, Theodore J; DenBesten, Pamela; Bronckers, Antonius L J J

    2014-07-01

    Supra-optimal intake of sodium fluoride (NaF) during early childhood results in formation of irreversible enamel defects. Monofluorophosphate (MFP) was considered as less toxic than NaF but equally cariostatic. We compared the potency of MFP and NaF to induce pre-eruptive sub-ameloblastic cysts and post-eruptive white spots and pits in developing hamster enamel. Hamster pups were injected subcutaneously with either NaF or MFP in equimolar doses of either 9 mg or 18 mg F/kg body weight. At 9 mg F/kg, MFP induced more but smaller sub-ameloblastic cysts with a collective cyst volume twice as large as that induced by NaF. Eight days after F injection, all F-injected groups had formed 4-6 white spots per molar, with an additional 2 pits per molar in the low MFP group. Twenty-eight days after injection, most white spots had turned into pits (5-6 per molar) and only the high MFP group still contained 2 white spots per molar. We conclude that parenterally applied MFP is more potent in inducing enamel defects than NaF. Most white spots formed turn into pits by functional use of the dentition. The higher potency of parenteral MFP may be associated with sustained elevated F levels in the enamel organ by enzymatic hydrolysis of MFP by alkaline phosphatase activity.

  11. Tenoxicam for pain relief following third molar surgery.

    PubMed

    Cheung, L K; Rodrigo, C

    1992-01-01

    Tenoxicam is a long-acting nonsteroidal anti-inflammatory agent that appears to have the ability to control pain of musculoskeletal origin. A double-blind randomized crossover study was designed to determine the efficacy of tenoxicam for pain relief following third molar surgery by comparing it with paracetamol. Immediately before surgery, 30 Chinese patients with bilateral symmetrically impacted mandibular third molars were given 40 mg of tenoxicam for surgery on one side and 1,000 mg of paracetamol for surgery on the other. Both paracetamol and tenoxicam were efficient as pain relievers after third molar surgery. Tenoxicam had comparable efficacy to paracetamol, but did not provide any advantage in terms of duration of action. The discrepancy between the clinical observation and pharmacokinetic prediction may be related to the strong serum binding property of tenoxicam. PMID:1298491

  12. Transcervical removal of an impacted third molar: an uncommon indication.

    PubMed

    Singh, Yash K; Adamo, Arthur K; Parikh, Niral; Buchbinder, Daniel

    2014-03-01

    This article presents a case of and reviews the literature involving the extraoral approach for surgical removal of an ectopic mandibular third molar tooth. Case reports describing extraction of the mandibular third molar using the extraoral approach are very limited. This article describes an unusual case of an impacted, infected, ectopic right mandibular third molar that was positioned at the inferior border and had caused an extraoral draining sinus. Furthermore, the roots were intimately involved with the inferior alveolar nerve (IAN) and had perforated the buccal cortex of the mandible. Surgical removal using a transcervical submandibular approach was deemed necessary to try to preserve the IAN and avoid fracture of the mandible in this 74-year-old patient.

  13. Pendulum Therapy of Molar Distalization in Mixed Dentition

    PubMed Central

    Prakash, Amit; Agarwal, Anshu

    2016-01-01

    ABSTRACT Early and timely pedo-orthodontic treatment is aimed at eliminating the disturbances of skeletal or dentoalveolar development, to harmonize the stomatognathic system before the full eruption of all permanent teeth. The advantages of pendulum appliance are its minimal dependence on patient’s compliance (child cooperation), ease of fabrication, onetime activation and adjustment of the springs if necessary to correct minor transverse and vertical molar positions. This article reports a successful treatment method of class II malocclusion with pendulum appliance in mixed dentition phase. Distalization of maxillary molar was done, followed by guidance of canine impaction orthodontically and other dental correction using 0.022 MBT appliances. Posttreatment results were stable and remarkable. How to cite this article: Patil RU, Prakash A, Agarwal A. Pendulum Therapy of Molar Distalization in Mixed Dentition. Int J Clin Pediatr Dent 2016;9(1):67-73. PMID:27274159

  14. First permanent molar root development arrest associated with compound odontoma.

    PubMed

    Gunda, Sachin A; Patil, Anil; Varekar, Aniruddha

    2013-07-04

    Trauma or infection to the primary tooth may have deleterious effects on the underlying developing tooth buds. Anatomically the root apices of primary teeth are in close proximity to the developing permanent tooth buds; hence spread of infection originating from pulp necrosis of primary tooth may not only affect the underlying tooth bud but may also affect the adjacent tooth buds. The extent of malformation depends on the developmental stage of tooth or the age of patient. Presented here is a rare case of complete arrest of maxillary first permanent molar root growth due to spread of periapical infection originating from second primary molar leading to failure of its eruption and finally extraction. Histopathlogical analysis revealed compound odontoma associated with maxillary first permanent molar.

  15. Pendulum Therapy of Molar Distalization in Mixed Dentition.

    PubMed

    Patil, Raju Umaji; Prakash, Amit; Agarwal, Anshu

    2016-01-01

    Early and timely pedo-orthodontic treatment is aimed at eliminating the disturbances of skeletal or dentoalveolar development, to harmonize the stomatognathic system before the full eruption of all permanent teeth. The advantages of pendulum appliance are its minimal dependence on patient's compliance (child cooperation), ease of fabrication, onetime activation and adjustment of the springs if necessary to correct minor transverse and vertical molar positions. This article reports a successful treatment method of class II malocclusion with pendulum appliance in mixed dentition phase. Distalization of maxillary molar was done, followed by guidance of canine impaction orthodontically and other dental correction using 0.022 MBT appliances. Posttreatment results were stable and remarkable. How to cite this article: Patil RU, Prakash A, Agarwal A. Pendulum Therapy of Molar Distalization in Mixed Dentition. Int J Clin Pediatr Dent 2016;9(1):67-73. PMID:27274159

  16. Microbiology of the pericoronal pouch in mandibular third molar pericoronitis.

    PubMed

    Leung, W K; Theilade, E; Comfort, M B; Lim, P L

    1993-10-01

    The microorganisms associated with mandibular third molar pericoronitis were investigated using direct microscopy and anaerobic culture method. The pericoronal pouch was sampled with paper points in A) 8 patients without mandibular third molar pericoronitis and B) 6 patients with mandibular third molar pericoronitis. Under the microscope, the microflora was found to be a complex mixture comprising gram-positive and gram-negative cocci, rods and filaments (including fusiform and curved rods), motile rods and spirochetes. Significantly higher proportions of motile, gram-negative rods were found in group B than in group A. The predominant cultivable microflora of 9 samples: A (4) and B (5) comprised several species of facultative and obligate anaerobic bacteria, namely Peptostreptococcus, Streptococcus, Actinomyces, Eubacterium, Propionibacterium, Veillonella, Porphyromonas, Prevotella, Bacteriodes, Fusobacterium, Campylobacter, Staphylococcus, Stomatococcus, Lactobacillus, Neisseria, Capnocytophaga, Haemophilus, Selenomonas and Centipeda species. The microflora in pericoronitis appeared similar to that of diseased periodontal pockets.

  17. Pendulum Therapy of Molar Distalization in Mixed Dentition.

    PubMed

    Patil, Raju Umaji; Prakash, Amit; Agarwal, Anshu

    2016-01-01

    Early and timely pedo-orthodontic treatment is aimed at eliminating the disturbances of skeletal or dentoalveolar development, to harmonize the stomatognathic system before the full eruption of all permanent teeth. The advantages of pendulum appliance are its minimal dependence on patient's compliance (child cooperation), ease of fabrication, onetime activation and adjustment of the springs if necessary to correct minor transverse and vertical molar positions. This article reports a successful treatment method of class II malocclusion with pendulum appliance in mixed dentition phase. Distalization of maxillary molar was done, followed by guidance of canine impaction orthodontically and other dental correction using 0.022 MBT appliances. Posttreatment results were stable and remarkable. How to cite this article: Patil RU, Prakash A, Agarwal A. Pendulum Therapy of Molar Distalization in Mixed Dentition. Int J Clin Pediatr Dent 2016;9(1):67-73.

  18. The effective molarity (EM)--a computational approach.

    PubMed

    Karaman, Rafik

    2010-08-01

    The effective molarity (EM) for 12 intramolecular S(N)2 processes involving the formation of substituted aziridines and substituted epoxides were computed using ab initio and DFT calculation methods. Strong correlation was found between the calculated effective molarity and the experimentally determined values. This result could open a door for obtaining EM values for intramolecular processes that are difficult to be experimentally provided. Furthermore, the calculation results reveal that the driving forces for ring-closing reactions in the two different systems are proximity orientation of the nucleophile to the electrophile and the ground strain energies of the products and the reactants.

  19. Clinical analysis of molar fissures by Cone-beam tomography.

    PubMed

    Cruvinel, V R N; Azevedo, B C; Gravina, D B L; Toledo, O A; Bezerra, A C B

    2007-01-01

    This study aimed to validate clinical analysis of 20 pediatric dentists on occlusal groove-fossa-system of molar depth comparing to Cone-beam tomography. The 48 sound third molars were visually classified from the shallowest to the deepest. Images were taken from the Accuitomo 3DX. There was a fair correlation between clinical analysis and the tomographic scorings (rs = 0.238; P = 0.103). It was concluded that pediatric dentists were not able to classify the fissures depth by visual analysis correctly. PMID:19161057

  20. 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

  1. Low-temperature heat capacities and standard molar enthalpy of formation of pyridine-2,6-dicarboxylic acid

    NASA Astrophysics Data System (ADS)

    Yang, Wei-Wei; Di, You-Ying; Kong, Yu-Xia; Tan, Zhi-Cheng

    2010-06-01

    This paper reports that the low-temperature heat capacities of pyridine-2,6-dicarboxylic acid were measured by a precision automatic calorimeter over a temperature range from 78 K to 380 K. A polynomial equation of heat capacities as a function of temperature was fitted by the least-squares method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at intervals of 5 K. The constant-volume energy of combustion of the compound was determined by means of a precision rotating-bomb combustion calorimeter. The standard molar enthalpy of combustion of the compound was derived from the constant-volume energy of combustion. The standard molar enthalpy of formation of the compound was calculated from a combination of the datum of the standard molar enthalpy of combustion of the compound with other auxiliary thermodynamic quantities through a Hess thermochemical cycle.

  2. Molar mass characterization of sodium carboxymethyl cellulose by SEC-MALLS.

    PubMed

    Shakun, Maryia; Maier, Helena; Heinze, Thomas; Kilz, Peter; Radke, Wolfgang

    2013-06-01

    Two series of sodium carboxymethyl celluloses (NaCMCs) derived from microcrystalline cellulose (Avicel samples) and cotton linters (BWL samples) with average degrees of substitution (DS) ranging from DS=0.45 to DS=1.55 were characterized by size exclusion chromatography with multi-angle laser light scattering detection (SEC-MALLS) in 100 mmol/L aqueous ammonium acetate (NH4OAc) as vaporizable eluent system. The application of vaporizable NH4OAc allows future use of the eluent system in two-dimensional separations employing evaporative light scattering detection (ELSD). The losses of samples during filtration and during the chromatographic experiment were determined. The scaling exponent as of the relation [Formula: see text] was approx. 0.61, showing that NaCMCs exhibit an expanded coil conformation in solution. No systematic dependencies of as on DS were observed. The dependences of molar mass on SEC-elution volume for samples of different DS can be well described by a common calibration curve, which is of advantage, as it allows the determination of molar masses of unknown samples by using the same calibration curve, irrespective of the DS of the NaCMC sample. Since no commercial NaCMC standards are available, correction factors were determined allowing converting a pullulan based calibration curve into a NaCMC calibration using the broad calibration approach. The weight average molar masses derived using the so established calibration curve closely agree with the ones determined by light scattering, proving the accuracy of the correction factors determined.

  3. 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

  4. 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 ... Practice . 7th ed. Philadelphia, PA: Elsevier; 2016:chap 101. ...

  5. 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.

  6. The chronology of third molar mineralization by digital orthopantomography.

    PubMed

    Maled, Venkatesh; Vishwanath, S B

    2016-10-01

    The present study was designed to determine the chronology of third molar mineralization to establish Indian reference data and to observe the advantages of digital orthopantomography. Therefore, a cross-sectional study was undertaken by evaluating 167 digital orthopantomographs in order to assess the mineralization status of the mandibular third molar of Caucasian individuals (85 males and 82 females) between the age of 14 and 24. The evaluation was carried out using the 8-stage developmental scheme of Demirjian et al (1973). The range, mean age, standard deviation and Student t-test are presented for each stage of mineralization in all four quadrants. Statistically significant differences between males and females were not found for all four third molars. All the individuals in this study with mature third molar were at least 18 years of age. For medicolegal purposes, the likelihood of whether an Indian is older than 18 years or not was determined. The advantage of digital orthopantomography in the interpretation of the tooth mineralization over the traditional method was acknowledged.

  7. Lower molar and incisor displacement associated with mandibular remodeling.

    PubMed

    Baumrind, S; Bravo, L A; Ben-Bassat, Y; Curry, S; Korn, E L

    1997-01-01

    The purpose of this study was to quantify the amount of alveolar modeling at the apices of the mandibular incisor and first molar specifically associated with appositional and resorptive changes on the lower border of the mandible during growth and treatment. Cephalometric data from superimpositions on anterior cranial base, mandibular implants of the Björk type, and anatomical "best fit" of mandibular border structures were integrated using a recently developed strategy, which is described. Data were available at annual intervals between 8.5 and 15.5 years for a previously described sample of approximately 30 children with implants. The average magnitudes of the changes at the root apices of the mandibular first molar and central incisor associated with modeling/remodeling of the mandibular border and symphysis were unexpectedly small. At the molar apex, mean values approximated zero in both anteroposterior and vertical directions. At the incisor apex, mean values approximated zero in the anteroposterior direction and averaged less than 0.15 mm/year in the vertical direction. Standard deviations were roughly equal for the molar and the incisor in both the anteroposterior and vertical directions. Dental displacement associated with surface modeling plays a smaller role in final tooth position in the mandible than in the maxilla. It may also be reasonably inferred that anatomical best-fit superimpositions made in the absence of implants give a more complete picture of hard tissue turnover in the mandible than they do in the maxilla.

  8. A Time for Heresy: A Molar Reading Model.

    ERIC Educational Resources Information Center

    Williamson, Leon E.

    A survey of the literature concerning the mental processes used in reading reveals a proliferation of molecular theories which explain only a small (and frequently neurological) component of the reading act. Enough information exists, however, to sketch an integrated, molar model of the reading process, which stresses the interrelationships…

  9. A cervical ectopic masquerading as a molar pregnancy.

    PubMed

    Masir, N; Tamby, M R; Jamil, M A

    2000-03-01

    We report a case of cervical pregnancy complicated by life threatening hemorrhage. An initial diagnosis of molar pregnancy was made preoperatively. During uterine evacuation she developed profuse hemorrhage which required an emergency hysterectomy for uncontrolled bleeding. Histopathological examination confirmed a cervical pregnancy. The clinical and pathological criteria for the diagnosis and the etiology of cervical pregnancy are discussed. PMID:11072500

  10. Management of Six Root Canals in Mandibular First Molar

    PubMed Central

    Gomes, Fabio de Almeida; Sousa, Bruno Carvalho

    2015-01-01

    Success in root canal treatment is achieved after thorough cleaning, shaping, and obturation of the root canal system. This clinical case describes conventional root canal treatment of an unusual mandibular first molar with six root canals. The prognosis for endodontic treatment in teeth with abnormal morphology is unfavorable if the clinician fails to recognize extra root canals. PMID:25685156

  11. The chronology of third molar mineralization by digital orthopantomography.

    PubMed

    Maled, Venkatesh; Vishwanath, S B

    2016-10-01

    The present study was designed to determine the chronology of third molar mineralization to establish Indian reference data and to observe the advantages of digital orthopantomography. Therefore, a cross-sectional study was undertaken by evaluating 167 digital orthopantomographs in order to assess the mineralization status of the mandibular third molar of Caucasian individuals (85 males and 82 females) between the age of 14 and 24. The evaluation was carried out using the 8-stage developmental scheme of Demirjian et al (1973). The range, mean age, standard deviation and Student t-test are presented for each stage of mineralization in all four quadrants. Statistically significant differences between males and females were not found for all four third molars. All the individuals in this study with mature third molar were at least 18 years of age. For medicolegal purposes, the likelihood of whether an Indian is older than 18 years or not was determined. The advantage of digital orthopantomography in the interpretation of the tooth mineralization over the traditional method was acknowledged. PMID:27485643

  12. [Half-molar sodium-lactate: The osmotic agent we are looking for?].

    PubMed

    Aramendi, I; Manzanares, W; Biestro, A

    2016-03-01

    Intracranial hypertension (ICH) is the most important modifiable factor with predictive negative value in brain injury patients. Osmotherapy is the most important first level specific measure in the treatment of ICH. Mannitol 20%, and 3, 7.5, 10, and 23% hypertonic sodium chloride are the most commonly used osmotic agents in the neurocritical care setting. Currently, controversy about the best osmotic agent remains elusive. Therefore, over the past few years, half-molar sodium lactate has been introduced as a new osmotic agent to be administered in the critically ill. Lactate is able to prevent hyperchloremia, as well as its adverse effects such as hyperchloremic acidosis, systemic inflammation, and acute kidney injury. Furthermore, lactate may also be used by glia as energy substrate in brain injury patients. Half-molar sodium lactate would also have a more potent and long-lasting effect decreasing intracellular osmolarity and by inhibiting neuronal volume control mechanisms. Pioneering researches in patients with traumatic brain injury have shown a more significant effect than mannitol on the control of ICH. In addition, in this group of patients this solution appears to be beneficial in preventing episodes of ICH. However, future research is necessary to corroborate or not these promising results.

  13. 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

  14. 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 2.75–5.52, P < 0.0001). Patients receiving the piezoelectric technique had less swelling at postoperative days 1, 3, 5, and 7 (all Ps ≤0.023). Additionally, there was a trend of less postoperative pain and trismus in the piezosurgery groups. The number of included randomized controlled

  15. 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.

  16. Exploring metameric variation in human molars: a morphological study using morphometric mapping.

    PubMed

    Morita, Wataru; Morimoto, Naoki; Ohshima, Hayato

    2016-09-01

    Human molars exhibit a type of metameric variation, which is the difference in serially repeated morphology within an organism. Various theories have been proposed to explain how this variation is brought about in the molars. Actualistic data that support the theories, however, are still relatively scarce because of methodological limitations. Here we propose new methods to analyse detailed tooth crown morphologies. We applied morphometric mapping to the enamel-dentine junction of human maxillary molars and examined whether odontogenetic models were adaptable to human maxillary molars. Our results showed that the upper first molar is phenotypically distinct among the maxillary molars. The average shape of the upper first molar is characterized by four well-defined cusps and precipitous surface relief of the occlusal table. On the other hand, upper third molar is characterized by smooth surface relief of the occlusal table and shows greater shape variation and distinct distribution patterns in morphospace. The upper second molar represents an intermediate state between first and third molar. Size-related shape variation was investigated by the allometric vector analysis, and it appeared that human maxillary molars tend to converge toward the shape of the upper first molar as the size increases. Differences between the upper first molar and the upper second and third molar can thus be largely explained as an effect of allometry. Collectively, these results indicate that the observed pattern of metameric variation in human molars is consistent with odontogenetic models of molar row structure (inhibitory cascade model) and molar crown morphology (patterning cascade model). This study shows that morphometric mapping is a useful tool to visualize and quantify the morphological features of teeth, which can provide the basis for a better understanding of tooth evolution linking morphology and development. PMID:27098351

  17. [The relation of pericoronitis to the position of the mandibular third molar].

    PubMed

    Lee, D K; Kim, B J

    1989-02-01

    Pericoronitis is the most commonly encountered pathologic condition involving the mandibular third molar. Because of the dangers associated with mandibular third molar pericoronitis, prophylactic extraction of third molar at high risk has been recommended. We studied 411 patients with mandibular third molar pericoronitis by clinical symptoms and radiographic measurement of mandibular third molar height, wideth and angulation. The results were as follows: 1. Mandibular third molar pericoronitis is frequently seen in third decade and there are no sexual difference significantely. 2. In inflammatory type of mandibular third molar pericoronitis, chronic pericoronitis occured more frequently than acute type. 3. In relation to angulation and height, mandibular third molar most likely to be afflicted with pericoronitis is vertical eruption at occlusal plane of the second molar. 4. In relation to angulation and width, it appears that the position of the mandibular third molar most likely to be afflicted with pericoronitis is in a vertically erupted tooth of which the space between the ramus and the distal side of the second molar is less than the mesiodistal diameter of crown. (Class II). 5. In relation to height and width, it appears that the position of the mandibular third molar most likely to be afflicted with pericoronitis is class II width (described above)at occlusal plane of the second molar.

  18. 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.

  19. Conservation Development in the Partially Sighted Child.

    ERIC Educational Resources Information Center

    Swanson, Lee; And Others

    1979-01-01

    A comparative study of conservation development in partially sighted, sighted, and sighted blindfolded children at four age levels was assessed. Conservation on tasks of mass, weight, and volume were evaluated using Piaget and Inhelder's prediction, judgment, and explanation questions. The significant differences were found between groups, task,…

  20. Thermodynamic properties of binary mixtures containing cycloalkanones; Excess volumes of cycloalkanones + cyclohexane, + benzene, and + tetrachloromethane

    SciTech Connect

    Dernini, S.; Polcaro, A.M.; Ricci, P.F. ); Marongiu, B. )

    1989-04-01

    Molar excess volumes have been determined by means of a vibrating-tube densimeter for binary liquid mixtures of cycloalkanones (cyclopentanone and cyclohexanone) + cyclohexane, + benzene, and + tetrachloromethane. The V/sup E/ data are reported over the complete mole fraction range at 288.15, 298.15, and 308.15{Kappa}. The obtained excess volumes are positive for mixtures of cyclopentanone with cyclohexane and are negative for mixtures of the cycloalkanones with benzene and tetrachloromethane; for the system cyclohexanone-cyclohexane the V/sup E/ values are positive for a wide range of mole fraction, but at very low cyclohexane mole fraction an inversion of the sign of V/sup E/ is observed. The data show that in the considered range of temperature the values of the temperature coefficient ({partial derivative}V/sup E//{partial derivative}T) are negative for mixtures of the cycloalkanones with benzene and are almost zero for mixtures with cyclohexane and with tetrachloromethane.

  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.

  2. 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

  3. 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.

  4. 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

  5. Periodontal pathogens in erupting third molars of periodontally healthy subjects.

    PubMed

    Rajasuo, A; Sihvonen, O J; Peltola, M; Meurman, J H

    2007-09-01

    The presence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia and Tannerella forsythensis in bacteriologic samples of 5-7-mm deep mandibular third-molar pericoronal pockets was analysed by polymerase chain reaction, to test the hypothesis that these sites would harbour the bacteria. The patients were periodontally healthy 20-year-old Finnish male conscripts. Sixteen had acute pericoronitis, 28 chronic pericoronitis, and 15 were symptom-free controls. A. actinomycetemcomitans was detected in only 7% of the samples from chronic pericoronitis cases, whereas P. gingivalis was positive in 20% of the symptom-free versus 69% (P = 0.018) of the acute and 57% (P = 0.044) of the chronic cases. The percentages for P. intermedia were 93, 94 and 93%, and for T. forsythensis 47, 63 and 57%, respectively. These results confirm that, apart from A. actinomycetemcomitans, periodontopathogens are common in third-molar sites in periodontally healthy individuals.

  6. 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

  7. Effective molarity in a nucleic acid-controlled reaction.

    PubMed

    Catalano, Michael J; Price, Nathan E; Gates, Kent S

    2016-06-01

    Positioning of reactive functional groups within a DNA duplex can enable chemical reactions that otherwise would not occur to an appreciable extent. However, few studies have quantitatively defined the extent to which the enforced proximity of reaction partners in duplex DNA can favor chemical processes. Here, we measured substantial effective molarities (as high as 25M) afforded by duplex DNA to a reaction involving interstrand cross-link formation between 2'-deoxyadenosine and a 2-deoxyribose abasic (Ap) site.

  8. 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.

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

    PubMed Central

    Hineline, P N

    2001-01-01

    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

  10. 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

  11. Fate of the molar dental lamina in the monophyodont mouse.

    PubMed

    Dosedělová, Hana; Dumková, Jana; Lesot, Hervé; Glocová, Kristýna; Kunová, Michaela; Tucker, Abigail S; Veselá, Iva; Krejčí, Pavel; Tichý, František; Hampl, Aleš; Buchtová, 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

  12. High School Students' Ability to Solve Molarity Problems and Their Analog Counterparts.

    ERIC Educational Resources Information Center

    Gabel, Dorothy L.; Samuel, K. V.

    1986-01-01

    Investigated use of analog tasks for determining difficulties that high school chemistry students (N=619) might encounter in solving molarity problems. One finding is that analog task used is a predictor of success on a molarity test. (Author/JN)

  13. The third molar as an age marker in adolescents: new approach to age evaluation.

    PubMed

    Rozkovcova, Eva; Dostalova, Tatjana; Markova, Marie; Broukal, Zdenek

    2012-09-01

    Adolescence is a relatively short period between childhood and adulthood. It is very difficult to determine adulthood based on biological indicators. The third molar may be considered a potential age marker for the period between the ages of 16-21. Our study evaluated a set of 1700 panoramic radiographs of individuals aged between 5 and 21 years. Results confirmed the statistically significant difference in the course of third molars development. The mean deviation for individuals with one third molar agenesis is -0.98 years, for individuals with two third molars agenesis -1.89 years, and with three molars agenesis -3.28 years. Thus, the extent of the deviation is directly proportional to the number of unformed third molars. The calculation of age according to the mean of stages of all third molars could lead to the underestimation of age. No intergender differences were found. Age determination using third molars could be used for forensic purposes.

  14. Spontaneous emergence of overgrown molar teeth in a colony of Prairie voles (Microtus ochrogaster).

    PubMed

    Jheon, Andrew H; Prochazkova, Michaela; Sherman, Michael; Manoli, Devanand S; Shah, Nirao M; Carbone, Lawrence; Klein, Ophir

    2015-03-01

    Continuously growing incisors are common to all rodents, which include the Microtus genus of voles. However, unlike many rodents, voles also possess continuously growing molars. Here, we report spontaneous molar defects in a population of Prairie voles (Microtus ochrogaster). We identified bilateral protuberances on the ventral surface of the mandible in several voles in our colony. In some cases, the protuberances broke through the cortical bone. The mandibular molars became exposed and infected, and the maxillary molars entered the cranial vault. Visualisation upon soft tissue removal and microcomputed tomography (microCT) analyses confirmed that the protuberances were caused by the overgrowth of the apical ends of the molar teeth. We speculate that the unrestricted growth of the molars was due to the misregulation of the molar dental stem cell niche. Further study of this molar phenotype may yield additional insight into stem cell regulation and the evolution and development of continuously growing teeth. PMID:25634121

  15. Spontaneous emergence of overgrown molar teeth in a colony of Prairie voles (Microtus ochrogaster).

    PubMed

    Jheon, Andrew H; Prochazkova, Michaela; Sherman, Michael; Manoli, Devanand S; Shah, Nirao M; Carbone, Lawrence; Klein, Ophir

    2015-03-23

    Continuously growing incisors are common to all rodents, which include the Microtus genus of voles. However, unlike many rodents, voles also possess continuously growing molars. Here, we report spontaneous molar defects in a population of Prairie voles (Microtus ochrogaster). We identified bilateral protuberances on the ventral surface of the mandible in several voles in our colony. In some cases, the protuberances broke through the cortical bone. The mandibular molars became exposed and infected, and the maxillary molars entered the cranial vault. Visualisation upon soft tissue removal and microcomputed tomography (microCT) analyses confirmed that the protuberances were caused by the overgrowth of the apical ends of the molar teeth. We speculate that the unrestricted growth of the molars was due to the misregulation of the molar dental stem cell niche. Further study of this molar phenotype may yield additional insight into stem cell regulation and the evolution and development of continuously growing teeth.

  16. Spontaneous emergence of overgrown molar teeth in a colony of Prairie voles (Microtus ochrogaster)

    PubMed Central

    Jheon, Andrew H; Prochazkova, Michaela; Sherman, Michael; Manoli, Devanand S; Shah, Nirao M; Carbone, Lawrence; Klein, Ophir

    2015-01-01

    Continuously growing incisors are common to all rodents, which include the Microtus genus of voles. However, unlike many rodents, voles also possess continuously growing molars. Here, we report spontaneous molar defects in a population of Prairie voles (Microtus ochrogaster). We identified bilateral protuberances on the ventral surface of the mandible in several voles in our colony. In some cases, the protuberances broke through the cortical bone. The mandibular molars became exposed and infected, and the maxillary molars entered the cranial vault. Visualisation upon soft tissue removal and microcomputed tomography (microCT) analyses confirmed that the protuberances were caused by the overgrowth of the apical ends of the molar teeth. We speculate that the unrestricted growth of the molars was due to the misregulation of the molar dental stem cell niche. Further study of this molar phenotype may yield additional insight into stem cell regulation and the evolution and development of continuously growing teeth. PMID:25634121

  17. Quality of life following third molar removal under conscious sedation

    PubMed Central

    Sancho-Puchades, Manuel; Berini-Aytés, Leonardo; Gay-Escoda, Cosme

    2012-01-01

    Aim: The aim of this study was to assess quality of life (QoL) and degree of satisfaction among outpatients subjected to surgical extraction of all four third molars under conscious sedation. A second objective was to describe the evolution of self-reported pain measured in a visual analogue scale (VAS) in the 7 days after extraction. Study design: Fifty patients received a questionnaire assessing social isolation, working isolation, eating and speaking ability, diet modifications, sleep impairment, changes in physical appearance, discomfort at suture removal and overall satisfaction at days 4 and 7 after surgery. Pain was recorded by patients on a 100-mm pain visual analogue scale (VAS) every day after extraction until day 7. Results: Thirty-nine patients fulfilled correctly the questionnaire. Postoperative pain values suffered small fluctuations until day 5 (range: 23 to 33 mm in a 100-mm VAS), when dicreased significantly. A positive association was observed between difficult ranked surgeries and higher postoperative pain levels. The average number of days for which the patient stopped working was 4.9. Conclusion: The removal of all third molars in a single appointment causes an important deterioration of the patient’s QoL during the first postoperative week, especially due to local pain and eating discomfort. Key words:Third molar removal, quality of life, sedation. PMID:22926461

  18. Lower molar shape and size in prosimian and platyrrhine primates.

    PubMed

    St Clair, Elizabeth M; Boyer, Doug M

    2016-10-01

    The goal of this research is to evaluate the relative strength of the influences of diet, size, and phylogenetic signal on dental geometric shape. Accurate comprehension of these factors and their interaction is important for reconstructing diet and deriving characters for a cladistic analysis in fossil primates. Geometric morphometric analysis is used to identify axes of shape variation in the lower second molars of (a) prosimian primates and (b) platyrrhines. Landmarks were placed on µCT-generated surface renderings. Landmark configurations were aligned using generalized Procrustes analysis. Principal components analysis and phylogenetic principal components analysis (pPCA) were performed on species average landmark co-ordinates. pPCs were examined with phylogenetic generalized least squares analysis for association with size and with diet. PCs from both phylogenetic and non-phylogenetic analyses were sufficient to separate species by broad dietary categories, including insectivores and folivores. In neither analysis was pPC1 correlated with tooth size, but some other pPCs were significantly correlated with size. The pattern of association between pPCs and size altered when centroid size and dietary variables were combined in the model; effects of diet factors typically exceeded effects of size. These results indicate a dominant phylogenetic and dietary signal in molar shape but also show some shape change correlated with size in the absence of obvious dietary associations. Geometric morphometric analysis appears to be useful for tracking functional traits in molars, particularly in tracking differences between folivorous and insectivorous species.

  19. 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

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

    PubMed

    Dąbrowski, P; Nowaczewska, W; Stringer, C B; Compton, T; Kruszyński, 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.

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

    PubMed

    Dąbrowski, P; Nowaczewska, W; Stringer, C B; Compton, T; Kruszyński, 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

  2. 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

  3. Lower molar shape and size in prosimian and platyrrhine primates.

    PubMed

    St Clair, Elizabeth M; Boyer, Doug M

    2016-10-01

    The goal of this research is to evaluate the relative strength of the influences of diet, size, and phylogenetic signal on dental geometric shape. Accurate comprehension of these factors and their interaction is important for reconstructing diet and deriving characters for a cladistic analysis in fossil primates. Geometric morphometric analysis is used to identify axes of shape variation in the lower second molars of (a) prosimian primates and (b) platyrrhines. Landmarks were placed on µCT-generated surface renderings. Landmark configurations were aligned using generalized Procrustes analysis. Principal components analysis and phylogenetic principal components analysis (pPCA) were performed on species average landmark co-ordinates. pPCs were examined with phylogenetic generalized least squares analysis for association with size and with diet. PCs from both phylogenetic and non-phylogenetic analyses were sufficient to separate species by broad dietary categories, including insectivores and folivores. In neither analysis was pPC1 correlated with tooth size, but some other pPCs were significantly correlated with size. The pattern of association between pPCs and size altered when centroid size and dietary variables were combined in the model; effects of diet factors typically exceeded effects of size. These results indicate a dominant phylogenetic and dietary signal in molar shape but also show some shape change correlated with size in the absence of obvious dietary associations. Geometric morphometric analysis appears to be useful for tracking functional traits in molars, particularly in tracking differences between folivorous and insectivorous species. PMID:27312120

  4. 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.

  5. 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

  6. 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

  7. 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.

  8. Variable permanent mandibular first molar: Review of literature

    PubMed Central

    Ballullaya, Srinidhi V; Vemuri, Sayesh; Kumar, Pabbati Ravi

    2013-01-01

    Introduction: The success of root canal therapy depends on the locations of all the canals, thourough debridement and proper sealing. At times the clinicians are challenged with variations in morphology of root canal. This review article attempts to list out all the variations of permanent mandibular first molar published so for in the literature. Materials and Methods: An exhaustive search was undertaken using PUBMED database to identify published literature from 1900 to 2010 relating to the root canal morphology of permanent first molar by using key words. The selected artcles were obtained and reviewed. Results: Total ninty seven articles were selected out of which 50 were original article and forty seven were case reports. The incidence of third canal in mesial root was 0.95% to 15%. The incidence of three rooted mandibular first molar was 3% to 33%. Only ninety cases reported with c-shape canal configuration. Incidence of Taurodintism without congenital disorder was very rare. Conclusion: The root canal treatment requires proper knowlegde of variations in root canal morphology in order to recognise, disinfect and seal all portal of exit. This can be accomplished with proper diagnosis using newer modes, modification in access preparation, use of operating microscope, enhanced methods of disinfecting and sealing of all canals. PMID:23716959

  9. 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

  10. The Use of Narrow Diameter Implants in the Molar Area

    PubMed Central

    Saad, M.; Assaf, A.; Gerges, E.

    2016-01-01

    Implant rehabilitations in the posterior jaw are influenced by many factors such as the condition of the remaining teeth, the force factors related to the patient, the quality of the bone, the maintenance of the hygiene, the limited bone height, the type and extent of edentulism, and the nature of the opposing arch. The gold standard is to place a regular diameter implant (>3.7 mm) or a wide one to replace every missing molar. Unfortunately, due to horizontal bone resorption, this option is not possible without lateral bone augmentation. In this situation, narrow diameter implant (NDI < 3.5 mm) could be the alternative to lateral bone augmentation procedures. This paper presents a clinical study where NDIs were used for the replacement of missing molars. They were followed up to 11 years. Special considerations were observed and many parameters were evaluated. NDI could be used to replace missing molar in case of moderate horizontal bone resorption if strict guidelines are respected. Yet, future controlled prospective clinical trials are required to admit their use as scientific evidence. PMID:27293436

  11. 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

  12. 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,…

  13. Characteristics of hydrogen produced by partial oxidation and auto-thermal reforming in a small methanol reformer

    NASA Astrophysics Data System (ADS)

    Horng, Rong-Fang; Chou, Huann-Ming; Lee, Chiou-Hwang; Tsai, Hsien-Te

    This paper investigates experimentally, the transient characteristics of a small methanol reformer using partial oxidation (POX) and auto-thermal reforming (ATR) for fuel cell applications. The parameters varied were heating temperature, methanol supply rate, steady mode shifting temperature, O 2/C (O 2/CH 3OH) and S/C (H 2O/CH 3OH) molar ratios with the main aim of promoting a rapid response and a high flow rate of hydrogen. The experiments showed that a high steady mode shifting temperature resulted in a faster temperature rise at the catalyst outlet and vice versa and that a low steady mode shifting temperature resulted in a lower final hydrogen concentration. However, when the mode shifting temperature was too high, the hydrogen production response was not necessarily improved. It was subsequently shown that the optimum steady mode shifting temperature for this experimental set-up was approximately 75 °C. Further, the hydrogen concentration produced by the auto-thermal process was as high as 49.12% and the volume flow rate up to 23.0 L min -1 compared to 40.0% and 20.5 L min -1 produced by partial oxidation.

  14. Mandibular third molar development after mantle radiation in long-term survivors of childhood Hodgkin's disease

    SciTech Connect

    McGinnis, J.P. Jr.; Hopkins, K.P.; Thompson, E.I.; Hustu, H.O.

    1987-05-01

    Sequential panoramic radiographs were assessed for mandibular third molar development in 47 long-term survivors of childhood Hodgkin's disease after treatment with 37 Gy mantle field radiation. To make a comparison, panoramic radiographs of 149 healthy, nonirradiated children were reviewed for the presence of mandibular third molars. In children between the ages of 7 and 12 years, bilateral agenesis of mandibular third molars was more frequent in patients who had been treated with mantle radiation than in nonirradiated patients. Unilateral agenesis, crown hypoplasia, and root growth impairment of mandibular third molars were also found. Similar, apparent, radiation-induced developmental anomalies were noted in maxillary third molars of the irradiated patients.

  15. Volume crossover in deeply supercooled water adiabatically freezing under isobaric conditions.

    PubMed

    Aliotta, Francesco; Giaquinta, Paolo V; Pochylski, Mikolaj; Ponterio, Rosina C; Prestipino, Santi; Saija, Franz; Vasi, Cirino

    2013-05-14

    The irreversible return of a supercooled liquid to stable thermodynamic equilibrium often begins as a fast process which adiabatically drives the system to solid-liquid coexistence. Only at a later stage will solidification proceed with the expected exchange of thermal energy with the external bath. In this paper we discuss some aspects of the adiabatic freezing of metastable water at constant pressure. In particular, we investigated the thermal behavior of the isobaric gap between the molar volume of supercooled water and that of the warmer ice-water mixture which eventually forms at equilibrium. The available experimental data at ambient pressure, extrapolated into the metastable region within the scheme provided by the reference IAPWS-95 formulation, show that water ordinarily expands upon (partially) freezing under isenthalpic conditions. However, the same scheme also suggests that, for increasing undercoolings, the volume gap is gradually reduced and eventually vanishes at a temperature close to the currently estimated homogeneous ice nucleation temperature. This behavior is contrasted with that of substances which do not display a volumetric anomaly. The effect of increasing pressures on the alleged volume crossover from an expanded to a contracted ice-water mixture is also discussed.

  16. Chiral and continuum extrapolation of partially quenched lattice results

    SciTech Connect

    C.R. Allton; W. Armour; D.B. Leinweber; A.W. Thomas; R.D. Young

    2005-04-01

    The vector meson mass is extracted from a large sample of partially quenched, two-flavor lattice QCD simulations. For the first time, discretization, finite-volume and partial quenching artifacts are treated in a unified chiral effective field theory analysis of the lattice simulation results.

  17. 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.

  18. Compensation trends of the angulation of first molars: retrospective study of 1 403 malocclusion cases

    PubMed Central

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

    2014-01-01

    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 1 403 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

  19. Effect of bite force on orthodontic mini-implants in the molar region: Finite element analysis

    PubMed Central

    Lee, Hyeon-Jung; Lee, Kyung-Sook; Kim, Min-Ji

    2013-01-01

    Objective To examine the effect of bite force on the displacement and stress distribution of orthodontic mini-implants (OMIs) in the molar region according to placement site, insertion angle, and loading direction. Methods Five finite element models were created using micro-computed tomography (microCT) images of the maxilla and mandible. OMIs were placed at one maxillary and two mandibular positions: between the maxillary second premolar and first molar, between the mandibular second premolar and first molar, and between the mandibular first and second molars. The OMIs were inserted at angles of 45° and 90° to the buccal surface of the cortical bone. A bite force of 25 kg was applied to the 10 occlusal contact points of the second premolar, first molar, and second molar. The loading directions were 0°, 5°, and 10° to the long axis of the tooth. Results With regard to placement site, the displacement and stress were greatest for the OMI placed between the mandibular first molar and second molar, and smallest for the OMI placed between the maxillary second premolar and first molar. In the mandibular molar region, the angled OMI showed slightly less displacement than the OMI placed at 90°. The maximum Von Mises stress increased with the inclination of the loading direction. Conclusions These results suggest that placement of OMIs between the second premolar and first molar at 45° to the cortical bone reduces the effect of bite force on OMIs. PMID:24228236

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

    PubMed Central

    Gómez-Santos, Laila; Sánchez-Torres, Alba; Herráez-Vilas, José-María

    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

  1. Modified distal shoe appliance for the loss of a primary second molar: a case report.

    PubMed

    Dhull, Kanika Singh; Bhojraj, Nandlal; Yadav, Shweta; Prabhakaran, Sheeja Devi

    2011-01-01

    Preservation of primary teeth until their normal exfoliation plays a crucial role in preventive and interceptive dentistry. Premature loss of the primary second molar prior to the eruption of the permanent first molar in the absence of the primary second molar can lead to mesial movement and migration of the permanent molar before and during its eruption. In such cases, an intra-alveolar type of space maintainer to guide the eruption of the permanent first molar is indicated. In certain cases, however, the conventional design is not practical. This paper describes a new design for distal shoe appliances in cases of primary second molar loss prior to the eruption of the permanent mandibular first molar.

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

    PubMed

    Galić, Ivan; Lauc, Tomislav; Brkić, Hrvoje; Vodanović, Marin; Galić, 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.

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

    PubMed

    Galić, Ivan; Lauc, Tomislav; Brkić, Hrvoje; Vodanović, Marin; Galić, 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

  4. [Molar incisor hypomineralization (MIH)--a literature review].

    PubMed

    Gotler, M; Ratson, T

    2010-04-01

    MIH was defined by Weerheijm (2001) as "hypomineralisation of systemic origin of 1-4 permanent first molars, frequently associated with affected incisors". The prevalence of MIH varies between 2.8% and 25%, dependent upon the study. At their sixth congress in 2003, The European Association of pediatric dentistry defined criteria for diagnosis of the phenomena. It included the presence of demarcated opacity, posteruptive enamel breakdown, atypical restoration, extracted molar due to MIH and unerupted teeth. According to the teeth involved and to the time of the crown formation, researches focused on environmental and systemic conditions as possible reasons for MIH.The etiologies were divided into five groups: Exposure to environmental contaminants, pre/peri and neonatal problems, exposure to fluoride, common childhood illnesses and medically compromised children. The clinical implications include highly sensitive teeth, difficulty to achieve adequate anesthesia, behavioral problems and anxiety, rapid progression of caries and the esthetic implications. A six step approach to management was described suggested: risk identification, early diagnosis, remineralization and desensitization, prevention of caries and posteruption breakdown, restorations and extractions and finally maintenance. Restoring an affected molar can vary from adhesive intra coronal restorations (resin composite is the material of choice) to extra coronal restorations (e.g. preformed metal crown). Esthetic solutions to affected incisors may include microabrasion (that shows little improvement) and resin composite or porcelain veneer. The key for a successful treatment is early diagnosis, intense follow up and usage of remineralizating agents as soon as the teeth erupt. There is still need for further research to clarify the etiological factors and improve the durability of restoration in affected teeth.

  5. 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

  6. The effective molarity (EM) puzzle in proton transfer reactions.

    PubMed

    Karaman, Rafik

    2009-08-01

    The DFT and HF calculation results for the proton transfer reactions of three different systems reveal that the reaction mechanism (transfer of a proton to a nucleophile) is largely determined by the distance between the two reactive centers (r). Systems with relatively large r values tend to abstract a proton from a molecule of water, whereas, these with a relatively small r values prefer to be engaged intramolecularly and their interaction with water is only via hydrogen bonding. Further, the results indicate that the effective molarity (logEM) for an intramolecular process is strongly correlated with the distance between the two reacting centers (r) in accordance with Menger's "spatiotemporal hypothesis".

  7. 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

  8. 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.

  9. 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

  10. Pericoronitis, deep fascial space infections, and the impacted third molar.

    PubMed

    Litonjua, L S

    1996-01-01

    Patients consulting the Philippine General Hospital Dentistry Department for management of impacted mandibular third molars were studied for the presence of pericoronits and deep fascial space infections. 18% of total cases presented an infection, while 13% presented with pericoronitis. 11% presented with deep fascial infection of which 72% were secondary to pericoronitis. A radiographic evaluation showed the vertical angulation (68%) with the highest portion at or above the occlusal level (70%) associated the most with pericoronits. The potential of pericoronitis developing to a deep space infection should always be considered.

  11. Human age estimation combining third molar and skeletal development.

    PubMed

    Thevissen, P W; Kaur, J; Willems, G

    2012-03-01

    The wide prediction intervals obtained with age estimation methods based on third molar development could be reduced by combining these dental observations with age-related skeletal information. Therefore, on cephalometric radiographs, the most accurate age-estimating skeletal variable and related registration method were searched and added to a regression model, with age as response and third molar stages as explanatory variable. In a pilot set up on a dataset of 496 (283 M; 213 F) cephalometric radiographs, the techniques of Baccetti et al. (2005) (BA), Seedat et al. (2005) (SE), Caldas et al. (2007) and Rai et al. (2008) (RA) were verified. In the main study, data from 460 (208 F, 224 M) individuals in an age range between 3 and 26 years, for which at the same day an orthopantogram and a cephalogram were taken, were collected. On the orthopantomograms, the left third molar development was registered using the scoring system described by Gleiser and Hunt (1955) and modified by Köhler (1994) (GH). On the cephalograms, cervical vertebrae development was registered according to the BA and SE techniques. A regression model, with age as response and the GH scores as explanatory variable, was fitted to the data. Next, information of BA, SE and BA + SE was, respectively, added to this model. From all obtained models, the determination coefficients and the root mean squared errors were calculated. Inclusion of information from cephalograms based on the BA, as well as the SE, technique improved the amount of explained variance in age acquired from panoramic radiographs using the GH technique with 48%. Inclusion of cephalometric BA + SE information marginally improved the previous result (+1%). The RMSE decreased with 1.93, 1.85 and 2.03 years by adding, respectively, BA, SE and BA + SE information to the GH model. The SE technique allows clinically the fastest and easiest registration of the degree of development of the cervical vertebrae. Therefore, the choice of

  12. 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.

  13. 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

    Peñarrocha-Diago, María A.; Peñarrocha-Oltra, David; Peñarrocha-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 case’s 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

  14. Twisted partially pure spinors

    NASA Astrophysics Data System (ADS)

    Herrera, Rafael; Tellez, Ivan

    2016-08-01

    Motivated by the relationship between orthogonal complex structures and pure spinors, we define twisted partially pure spinors in order to characterize spinorially subspaces of Euclidean space endowed with a complex structure.

  15. Lattice potential energy and standard molar enthalpy in the formation of 1—dodecylamine hydrobromide (1-C12H25NH3·Br)(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-C12H25NH3·Br)(s) has been synthesized using the liquid phase reaction method. The lattice potential energy of the compound 1-C12H25NH3·Br 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-C12H25NH3·Br(s) is measured to be ΔcUmo(1-C12H25NH3·Br, s) = -(7369.03±3.28) kJ·mol-1 by means of an RBC-II precision rotating-bomb combustion calorimeter at T = (298.15±0.001) K. The standard molar enthalpy of combustion of the compound is derived to be ΔcHmo(1-C12H25NH3·Br, s) = -(7384.52±3.28) kJ·mol-1 from the constant-volume energy of combustion. The standard molar enthalpy of formation of the compound is calculated to be ΔfHmo(1-C12H25NH3·Br, s)=-(1317.86±3.67) kJ·mol-1 from the standard molar enthalpy of combustion of the title compound and other auxiliary thermodynamic quantities through a thermochemical cycle.

  16. Intra- and interspecific variation in macaque molar enamel thickness.

    PubMed

    Kato, Akiko; Tang, Nancy; Borries, Carola; Papakyrikos, Amanda M; Hinde, Katie; Miller, Ellen; Kunimatsu, Yutaka; Hirasaki, Eishi; Shimizu, Daisuke; Smith, Tanya M

    2014-11-01

    Enamel thickness has played an important role in studies of primate taxonomy, phylogeny, and functional morphology, although its variation among hominins is poorly understood. Macaques parallel hominins in their widespread geographic distribution, relative range of body sizes, and radiation during the last five million years. To explore enamel thickness variation, we quantified average and relative enamel thickness (AET and RET) in Macaca arctoides, Macaca fascicularis, Macaca fuscata, Macaca mulatta, Macaca nemestrina, and Macaca sylvanus. Enamel area, dentine area, and enamel-dentine junction length were measured from mesial sections of 386 molars scanned with micro-computed tomography, yielding AET and RET indices. Intraspecific sex differences were not found in AET or RET. Macaca fuscata had the highest AET and RET, M. fascicularis showed the lowest AET, and M. arctoides had the lowest RET. The latitudinal distribution of macaque species was associated with AET for these six species. Temperate macaques had thicker molar enamel than did tropical macaques, suggesting that thick enamel may be adaptive in seasonal environments. Additional research is needed to determine if thick enamel in temperate macaques is a response to intensified hard-object feeding, increased abrasion, and/or a broader diet with a greater range of food material properties. The extreme ecological flexibility of macaques may prohibit identification of consistent trends between specific diets and enamel thickness conditions. Such complications of interpretation of ecological variability, dietary diversity, and enamel thickness may similarly apply for fossil Homo species.

  17. 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.

  18. Enamel thickness trends in Plio-Pleistocene hominin mandibular molars.

    PubMed

    Skinner, Matthew M; Alemseged, Zeresenay; Gaunitz, Charleen; Hublin, Jean-Jacques

    2015-08-01

    Enamel thickness continues to be an important morphological character in hominin systematics and is frequently invoked in dietary reconstructions of Plio-Pleistocene hominin taxa. However, to date, the majority of published data on molar enamel thickness of Pliocene and early Pleistocene hominins derive from naturally fractured random surfaces of a small number of specimens. In this study we systematically analyze enamel thickness in a large sample of Plio-Pleistocene fossil hominins (n = 99), extant hominoids (n = 57), and modern humans (n = 30). Based on analysis of 2D mesial planes of section derived from microtomography, we examine both average and relative enamel thickness, and the distribution of enamel across buccal, occlusal, and lingual components of mandibular molars. Our results confirm the trend of increasing enamel thickness during the Pliocene that culminates in the thick enamel of the robust Australopithecus species, and then decreases from early Homo to recent modern humans. All hominin taxa share a regional average enamel thickness pattern of thick occlusal enamel and greater buccal than lingual enamel thickness. Pan is unique in exhibiting the thinnest average enamel thickness in the occlusal basin. Statistical analysis indicates that among Pliocene hominins enamel thickness is a weak taxonomic discriminator. The data underlying these results are included in a table in the Supplementary Online Material. PMID:26024565

  19. Size and shape variability in human molars during odontogenesis.

    PubMed

    Morita, W; Yano, W; Nagaoka, T; Abe, M; Nakatsukasa, M

    2014-03-01

    Under the patterning cascade model (PCM) of cusp development inspired by developmental genetic studies, it is predicted that the location and the size of later-forming cusps are more variable than those of earlier-forming ones. Here we assessed whether differences in the variability among cusps in total and each particular crown component (enamel-dentin junction [EDJ], outer enamel surface [OES], and cement-enamel junction [CEJ]) could be explained by the PCM, using human maxillary permanent first molars (UM1) and second deciduous molars (um2). Specimens were µCT-scanned, and 3D models of EDJ and OES were reconstructed. Based on these models, landmark-based 3D geometric morphometric analyses were conducted. Size variability in both tooth types was generally consistent with the above prediction, and the differences in size variation among cusps were smaller for the crown components completed in later stages of odontogenesis. With a few exceptions, however, the prediction was unsupported regarding shape variability, and UM1 and um2 showed different patterns. Our findings suggested that the pattern of size variability would be caused by temporal factors such as the order of cusp initiation and the duration from the beginning of mineralization to the completion of crown formation, whereas shape variability may be affected by both topographic and temporal factors.

  20. 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.

  1. An in vitro morphological investigation of the endodontic spaces of third molars.

    PubMed

    Cosić, Jozo; Galić, Nada; Vodanović, Marin; Njemirovskij, Vera; Segović, Sanja; Pavelić, Bozidar; Anić, Ivica

    2013-06-01

    Aim of this paper was to investigate the particular anatomic features of the endodontic space of third molars in the general population of Croatia. A total of 106 fully developed third molars (56 maxillar and 50 mandibular) has been analyzed. The respective number of roots and of root canals, the structure of the roots, and the curvature and absolute length of the root-canals were analyzed. In most cases, upper third molars had three roots (83.9%), while most of the lower molars were single rooted (56.0%). Upper third molars had mostly three root canals (75.1%), lower third molars two (90.0%). In both jaws, most third molars had curved canals (60.7% in the upper and 84.0% in the lower jaw). 12.5% of upper third molars had lateral and accessory canals, whereas only 4.0% of the lower third molars were found to have them. The Student t-test showed statistically significant differences (p < 0.05) in the length of the root-canals, mesiobuccal and distobuccal canals being significantly shorter than palatinal canals. The same test showed that in the lower third molars the mesial root canals were significantly longer that the distal ones, although slightly. The results obtained are in compliance with similar results by other authors; however, they tend to show some specific population-related features. PMID:23940986

  2. An Evidenced Based Scoring System To Determine The Periodontal Prognosis On Molars

    PubMed Central

    Miller, Preston D.; McEntire, Mark L.; Marlow, Nicole M.; Gellin, Robert G.

    2014-01-01

    Background This retrospective study evaluated and assigned scores to six prognostic factors and derived a quantitative scoring system used to determine the periodontal prognosis on molar teeth. Methods Data were gathered on 816 molars in 102 patients with moderate to severe periodontitis. The six factors evaluated, age, probing depth, mobility, furcation involvement, smoking, and molar type, were assigned a numerical score based on statistical analysis. The sum of the scores for all factors was used to determine the prognosis score for each molar. Only patients with all first and second molars at the initial examination qualified for the study. All patients were a minimum of 15 years post treatment. Results The post treatment time ranged from 15 to 40 years and averaged 24 years. When the study was completed, 639 molars survived (78%), and of those surviving molars, 566 survived in health (89%). In molars with lower scores (1,2,and 3) the 15-year survival rates ranged from 99% to 96%. For scores 4, 5, 6 the 15 year survival rates ranged was 95% to 90% and for molars with scores of 7, 8, 9, and 10 the survival rates ranged from 86% to 67%. Conclusions Our results indicate that the periodontal prognosis on molars diagnosed with moderate to severe periodontitis can be calculated using an evidence-based scoring system. PMID:23725028

  3. Variance Components: Partialled vs. Common.

    ERIC Educational Resources Information Center

    Curtis, Ervin W.

    1985-01-01

    A new approach to partialling components is used. Like conventional partialling, this approach orthogonalizes variables by partitioning the scores or observations. Unlike conventional partialling, it yields a common component and two unique components. (Author/GDC)

  4. [The morphological study of experimental caries produced in rat molars].

    PubMed

    Tanaka, R

    1989-01-01

    Since there is some disagreement over the validity of using the rat for various experiments of relevance to dental caries in the human. The process of carious formation in the lower first and second molars of the rat was observed histologically. 120 new born Wistar rats were divided into two groups, one on a carious diet and the other on a standard diet. Both control and experimental animals were killed at preselected intervals namely 1 week, 4 weeks and 7 weeks after weaning. The maxillary and mandibular tooth bearing segments were removed and fixed in glutaraldehyde and osmium. After clinical examination and assessment of the caries status made with the aid of a binocular microscope, the material was sectioned without decalcification and prepared for light, electron, or microradiogram. From the results it was concluded that, 1. The caries process in the rat is extremely rapid much faster than in the human for example complete breakdown of the crown occurs within 28 days of weaning. 2. Frequently destruction of the dentin occurs before mineral loss is detectable in the enamel. 3. Rarely are any of the characteristic features of the early human caries lesion, such as the surface zone, body of the lesion, the dark zone and the translucent zone, to be found. 4. When a surface zone is visible, the dentine is usually in an advanced state of destruction. 5. The histopathology of rat caries does not therefore follow the same pattern as in the human. It is deduced that the reasons for these differences with the human lesion are due to. a) Rat molar enamel is extremely thin being only 100 microns in the thickest part of the fissure enamel whereas it is 2.5mm in the human. b) Rat molar enamel has a lower mineral density than the outer two thirds of human enamel, and is even lower (2.74) than the average value for the inner layer deciduous human enamel. (2.85-2.92) (Weidmann, et al., 1967) c) Rat enamel is extremely porous allowing easy diffusion of fluid and dyes. d) This

  5. [Fiber-reinforced adhesive partial dentures].

    PubMed

    Kreulen, C M

    2003-06-01

    Dental applications of fiber-reinforced polymers include adhesive partial dentures. Dental resin composite materials can be reinforced by several types of fibres. Fiber orientation, proper wetting of the fibers by the resin and fiber volume are important. An application of fiber reinforced composites is the composite inlay bridge. This paper deals with some aspects of this type of adhesive partial denture. Advantages include the satisfactory esthetics and the minimally invasive character. Not clear yet is the long-term survival. The adhesive properties of fiber-reinforced adhesive partial dentures require an adaptation of the current dental philosophy, in which direct and indirect restorative techniques can be combined. An increase in knowledge and experience is needed to determine the dental applications. PMID:12852063

  6. 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.

  7. Methanol partial oxidation reformer

    DOEpatents

    Ahmed, Shabbir; Kumar, Romesh; Krumpelt, Michael

    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.

  8. Methanol partial oxidation reformer

    DOEpatents

    Ahmed, Shabbir; Kumar, Romesh; Krumpelt, Michael

    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.

  9. 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.

  10. 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.

  11. Oxygen partial pressure sensor

    DOEpatents

    Dees, Dennis W.

    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.

  12. 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.

  13. Molarity (Aromic Density) of the Elements as Pure Crystals.

    ERIC Educational Resources Information Center

    Pauling, Linus; Herman, Zelek S.

    1985-01-01

    Provides background information for teachers on the atomic density of the elements as pure crystals. Atomic density is defined as the reciprocal of the atomic volume. Includes atomic-density diagrams which were prepared using the atomic-volume values given by Singman, supplemented by additional values for some allotropes. (JN)

  14. Efficiency of two protocols for maxillary molar intrusion with mini-implants

    PubMed Central

    Paccini, Juliana Volpato Curi; Cotrim-Ferreira, Flávio Augusto; Ferreira, Flávio Vellini; de Freitas, Karina Maria Salvatore; Cançado, Rodrigo Hermont; Valarelli, Fabrício Pinelli

    2016-01-01

    ABSTRACT Objective: The aim of this study was to compare the efficiency of two protocols for maxillary molar intrusion with two or three mini-implants. Methods: Twenty five maxillary first molars extruded for loss of their antagonists in adult subjects were selected. The sample was divided into two groups, according to the intrusion protocol with two or three mini-implants. Group 1 consisted of 15 molars that were intruded by two mini-implants. Group 2 consisted of 10 molars intruded by three mini-implants. Changes with treatment were analyzed in lateral cephalograms at the beginning and at the end of intrusion of maxillary molars. Results: Results showed that there was no difference in efficiency for the two intrusion protocols. It was concluded that extruded maxillary molars can be intruded with two or three mini-implants with similar efficiency. PMID:27409654

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

    PubMed Central

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

    2015-01-01

    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

  16. Dynamics of partial control.

    PubMed

    Sabuco, Juan; Sanjuán, Miguel A F; Yorke, James A

    2012-12-01

    Safe sets are a basic ingredient in the strategy of partial control of chaotic systems. Recently we have found an algorithm, the sculpting algorithm, which allows us to construct them, when they exist. Here we define another type of set, an asymptotic safe set, to which trajectories are attracted asymptotically when the partial control strategy is applied. We apply all these ideas to a specific example of a Duffing oscillator showing the geometry of these sets in phase space. The software for creating all the figures appearing in this paper is available as supplementary material. PMID:23278093

  17. Third molar consent forms: how comprehensive should they be?

    PubMed

    Britton, Danielle; Burns, Andrew; Hudyba, Stephen; Nugent, Michael

    2016-09-01

    To establish a gold standard for the information given to patients about the risks associated with third molar extractions, we surveyed 79 oral and maxillofacial surgeons (OMFS) to find out what information they gave to patients during the consent process. We also surveyed 62 medicolegal solicitors to find out what information they thought patients should be given before the procedure, and in what form. A total of 20/76 OMFS (26%) used a two-stage process to obtain consent; 13 (17%) included paraesthesia on the consent form and also gave out an information leaflet. All the lawyers agreed that patients should give their consent in writing and thought that the risk of paraesthesia should be included on the form. Three-quarters thought that they should also be given an information leaflet that includes paraesthesia. We encourage surgeons to do this as part of the two-stage consent process. PMID:27256800

  18. Single implant in the mandibular molar region of edentulous patient.

    PubMed

    Zhai, Jun-Jiang; Wen, Cai; Teng, Ming-Hua; Liang, Xing

    2013-09-01

    Implant-retained overdentures are a valid treatment option for edentulous patients, especially for patients with severe alveolar ridge atrophy. A central single implant is considered adequate to retain an overdenture in the edentulous mandible. However, for some patients, there is no sufficient bone height, or width in the interforaminal region of the mandible for insertion of the implant. This case report illustrates that the insertion of a single implant in the mandibular molar region might stabilize the prosthesis, and might improve the oral health-related quality of life and chewing function. A Locator attachment was used in this case to retain the overdenture. The one-year clinical results are promising. However, long-term clinical results and randomized clinical trials are needed before this method can be widely used in clinical application.

  19. Molar extinction coefficients of some carbohydrates in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Singh, K.; Sandhu, G. K.; Lark, B. S.; Sud, S. P.

    2002-03-01

    Molar extinction coefficients of some carbohydrates viz. L-arabinose (C5H10O5), D-glucose (C6H12O6), D-mannose (C6H12O6), D-galactose (C6H12O6), D(-) fructose (C6H12O6) and maltose (C12H24O12) in aqueous solutions have been determined at 81, 356, 511, 662, 1173 and 1332 keV by gamma ray transmission method in a narrow beam good geometry set-up. These coefficients have been found to depend upon the photon energy following a 4-parameter polynomial. These extinction coefficients for different sugars having the same molecular formula have same values varying within experimental uncertainty. Within concentration ranges studied, Beer--Lambert law is obeyed very well.

  20. Accurate and reproducible determination of lignin molar mass by acetobromination.

    PubMed

    Asikkala, Janne; Tamminen, Tarja; Argyropoulos, Dimitris S

    2012-09-12

    The accurate and reproducible determination of lignin molar mass by using size exclusion chromatography (SEC) is challenging. The lignin association effects, known to dominate underivatized lignins, have been thoroughly addressed by reaction with acetyl bromide in an excess of glacial acetic acid. The combination of a concerted acetylation with the introduction of bromine within the lignin alkyl side chains is thought to be responsible for the observed excellent solubilization characteristics acetobromination imparts to a variety of lignin samples. The proposed methodology was compared and contrasted to traditional lignin derivatization methods. In addition, side reactions that could possibly be induced under the acetobromination conditions were explored with native softwood (milled wood lignin, MWL) and technical (kraft) lignin. These efforts lend support toward the use of room temperature acetobromination being a facile, effective, and universal lignin derivatization medium proposed to be employed prior to SEC measurements. PMID:22870925

  1. Appositional enamel growth in molars of South African fossil hominids.

    PubMed

    Lacruz, Rodrigo S; Bromage, Timothy G

    2006-07-01

    Enamel is formed incrementally by the secretory activity of ameloblast cells. Variable stages of secretion result in the formation of structures known as cross striations along enamel prisms, for which experimental data demonstrate a correspondence with daily periods of secretion. Patterns of variation in this daily growth are important to understanding mechanisms of tooth formation and the development of enamel thickness. Transmitted light microscopy (TLM) of histological ground sections and scanning electron microscopy (SEM) of bulk specimens or their surface replicas are the usual methods for investigating cross striations. However, these methods pose some constraints on the study of these features in Plio-Pleistocene hominid enamel, the specimens of which may only rarely be sectioned for TLM or examined on only their most superficial surfaces for SEM. The recent development of portable confocal scanning optical microscopy (PCSOM) resolves some of the restrictions on fractured enamel surfaces, allowing the visualization of cross striations by direct examination. This technology has been applied here to the study of Australopithecus africanus and Paranthropus robustus hominid molars from the Plio-Pleistocene of South Africa. We hypothesize that these taxa have increased enamel appositional rates compared with modern humans, because despite having thicker enamelled molars (particularly P. robustus), the enamel crowns of these fossil taxa take an equivalent or reduced amount of time to form. Cross striations were measured in cuspal, lateral and cervical regions of the enamel crowns, and, within each region, the inner, middle and outer zones. Values obtained for A. africanus outer zones of the enamel crown are, in general, lower than those for P. robustus, indicating faster forming enamel in the latter, while both taxa show higher rates of enamel growth than modern humans and the African great apes. This demonstrates a relatively high degree of variability in the

  2. 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

  3. 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.

  4. 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.

  5. Saving the 2nd Molar from the 3rd Is it Really the Guilt of the Tilt?

    PubMed Central

    Yadav, Pankaj; Nawal, Ruchika Roongta; Talwar, Sangeeta; Verma, Mahesh

    2016-01-01

    Introduction Clinicians often relate the distal caries in second molars to angulated third molars, which if left undetected can lead to gross decay that may further require removal of the tooth. Due to this fact, many third molars are advised for prophylactic removal to prevent decay in the second molar. But this approach would only be justified when the incidence of decay/loss of second molar due to third molar are reasonably high. We sought to determine incidence of caries experience and also sequel extraction in second molars associated with the third molars. Aim The study was conducted to answer the basic question that whether the incidence of caries and subsequent extraction of second molar due to angulated third molars is high enough to justify the prophylactic removal of third molar or not. Materials and Methods This study was conducted on radiographic records of 1187 patients. The effect of tilted third molar on the second molar was measured in relation with three parameters namely level & position of third molar with respect to second molar and the distribution among arches. Results The results indicated that out of total number of teeth examined only 5.4% of maxillary and 9.6% of mandibular second molars were affected by tilted third molars. Further, only 2.2% of mandibular and 2.9% of maxillary second molars were indicated for extraction. The data was statistically insignificant. Conclusion It was concluded that distal caries in second molars is not very common. It may be present in some cases of third molar impactions and prophylactic removal of these impacted teeth may not be considered appropriate. PMID:27437353

  6. A Prospective Study of Clinical Outcomes Related to Third Molar Removal or Retention

    PubMed Central

    Cunha-Cruz, Joana; Rothen, Marilynn; Spiekerman, Charles; Drangsholt, Mark; Anderson, Loren; Roset, Gayle A.

    2014-01-01

    Objectives. We investigated outcomes of third molar removal or retention in adolescents and young adults. Methods. We recruited patients aged 16 to 22 years from a dental practice–based research network in the Pacific Northwest from May 2009 through September 2010 who had at least 1 third molar present and had never undergone third molar removal. Data were acquired via questionnaire and clinical examination at baseline, periodic online questionnaires, and clinical examination at 24 months. Results. A total of 801 patients participated. Among patients undergoing third molar removal, rates of paresthesia and jaw joint symptoms lasting more than 1 month were 6.3 and 34.3 per 100 person-years, respectively. Among patients not undergoing removal, corresponding rates were 0.7 and 8.8. Periodontal attachment loss at distal sites of second molars did not significantly differ by third molar removal status. Incident caries at the distal surfaces of second molars occurred in fewer than 1% of all sites. Conclusions. Rates of paresthesia and temporomandibular joint disorder were higher after third molar removal. Periodontal attachment loss and incident caries at the distal sites of second molars were not affected by extraction status. PMID:24524521

  7. Periodontal considerations in the use of bonds or bands on molars in adolescents and adults.

    PubMed

    Boyd, R L; Baumrind, S

    1992-01-01

    This longitudinal study compared the periodontal status of bonded and banded molars in 20 adult and 40 adolescent patients before, during and after treatment with fixed orthodontic appliances. Plaque accumulation (measured by the Plaque Index), gingival inflammation (measured by the Gingival Index and the bleeding tendency), and pocket depth were assessed by one examiner at sites along the mesio-buccal line angle of the maxillary right first molar and the mandibular left first molar. Assessments were made immediately prior to the placement of fixed appliances (pretreatment), at 1, 3, 6, 9, 12 and 18 months after appliances were placed; and 3 months after appliances were removed (posttreatment). Loss of attachment between the pretreatment and posttreatment visits also was determined. At pretreatment, no significant differences were found in gingival inflammation between maxillary and mandibular banded and bonded molars. During treatment, both maxillary and mandibular banded molars showed significantly (p less than 0.05) greater gingival inflammation and plaque accumulation than did bonded molars. Three months after appliance removal, the maxillary molars that had been banded continued to show significantly more gingival inflammation and loss of attachment than did the maxillary molars that had been bonded. When all banded and bonded teeth were grouped by patient age, mean values for plaque accumulation and gingival inflammation in the maxillary molar regions were significantly greater for adolescents than for adults.

  8. 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

  9. Partial knee replacement

    MedlinePlus

    ... You will need to understand what surgery and recovery will be like. Partial knee arthroplasty may be a good choice if you have arthritis in only one side or part of the knee and: You are older, thin, and not very active. You do not ...

  10. Influence of magnesia-to-phosphate molar ratio on microstructures, mechanical properties and thermal conductivity of magnesium potassium phosphate cement paste with large water-to-solid ratio

    SciTech Connect

    Xu, Biwan; Ma, Hongyan; Li, Zongjin

    2015-02-15

    This paper describes the influence of the magnesia-to-phosphate (M/P) molar ratios ranging from 4 to 12, on the properties and microstructures of magnesium potassium phosphate cement (MKPC) pastes with a large water-to-solid ratio (w/s) of 0.50. The setting behavior, compressive strength, tensile bonding strength and thermal conductivity of the MKPC pastes, were investigated. The results show that an increase in the M/P ratio can slow down the setting reaction, and clearly degrade the mechanical strengths, but clearly improve the thermal conductivity of MKPC pastes. Furthermore, micro-characterizations including X-ray diffraction, scanning electron microscopy and thermogravimetric analysis, on the MKPC pastes reveal that a lower M/P ratio can facilitate better crystallization of the resultant magnesium potassium phosphate hexahydrate (MKP) and a denser microstructure. Moreover, strong linear correlations are found between the mechanical strengths and the MKP-to-space ratio, and between thermal conductivity and the volume ratio of the unreacted magnesia to the MKP. - Highlights: • Increase of M/P molar ratio causes clear mechanical degradations on MKPC pastes. • Thermal conductivity of MKPC pastes is improved with increase of M/P molar ratio. • Lower M/P ratio leads to better MKP crystallization and denser microstructure. • Strengths of MKPC pastes are linearly correlated to the MKP-to-space ratios. • Thermal conductivity is affected by the volume ratio of unreacted magnesia to MKP.

  11. Implant-connected versus tooth-connected implant-supported partial dentures: 2-year clinical and radiographic comparative evaluation.

    PubMed

    Mostafa, Tamer Mohamed; El-Sheikh, Mohamed M; Abd El-Fattah, Fadel

    2015-01-01

    The purpose of this study was to clinically and radiographically compare implant-connected and tooth-connected implant-supported fixed-detachable mandibular partial dentures. Twenty partially edentulous patients (age range: 25 to 50 years) with mandibular Kennedy Class II configurations were equally divided into two groups receiving a three-unit, fixed-detachable, screw-retained partial denture. Group 1 comprised patients with unilateral missing mandibular molars and premolars. Two implants were placed at the mandibular first premolar and first molar areas. Group 2 comprised patients with missing mandibular molars and second premolars. An implant was placed at the mandibular first molar area, the first premolar was prepared, and a coping was cemented to the tooth with permanent cement. Each case was evaluated clinically and radiographically at baseline (partial denture insertion) and after 6, 12, and 24 months. Data were collected and statistically analyzed using repeated-measures one-way and two-way analysis of variance tests. There was no statistically significant difference between the two groups (P > .05). The implant-tooth-supported prosthesis provided an equally predictable treatment option compared to the totally implant-supported prosthesis in terms of implant survival and loss of marginal bone. PMID:25909533

  12. Conservative, non-surgical management of patients presenting with impacted lower third molars: a 5-year study.

    PubMed

    Hill, C M; Walker, R V

    2006-10-01

    Our aim was to find out what happened over a period of 5 years to fully or partially impacted mandibular third molars that were left alone. The change in emphasis towards non-intervention in patients with asymptomatic impacted wisdom teeth over the past few years was accompanied by considerable debate as to the eventual outcome of such teeth. Examination of a number of factors including smoking, extent of eruption, depth of periodontal pocket, and history of pericoronitis failed to show any predictive factors that would indicate which teeth would subsequently require removal. However, about one-third of the teeth in this series had to be removed within the 5-year period. Although this does not allow a 'lifetime extrapolation', it blurs the edges of our current thinking about asymptomatic wisdom teeth and certainly suggests that further (possibly longer term) studies need to be completed. It does, however, provide little support for the reintroduction of prophylactic removal of wisdom teeth.

  13. Cholesterol-induced variations in the volume and enthalpy fluctuations of lipid bilayers.

    PubMed

    Halstenberg, S; Heimburg, T; Hianik, T; Kaatze, U; Krivanek, R

    1998-07-01

    The sound velocity and density of suspensions of large unilamellar liposomes from dimyristoylphosphatidylcholine with admixed cholesterol have been measured as a function of temperature around the chain melting temperature of the phospholipid. The cholesterol-to-phospholipid molar ratio xc has been varied over a wide range (0 partial volume of the phospholipid, and of the apparent specific adiabatic compressibility have been derived from the measured data. These data are particularly discussed with respect to the volume fluctuations within the samples. A theoretical relation between the compressibility and the excess heat capacity of the bilayer system has been derived. Comparison of the compressibilities (and sound velocity numbers) with heat capacity traces display the close correlation between these quantities for bilayer systems. This correlation appears to be very useful as it allows some of the mechanical properties of membrane systems to be calculated from the specific heat capacity data and vice versa. PMID:9649386

  14. Appearance of dentin gamma-carboxyglutamic acid-containing proteins in developing rat molars in vitro

    SciTech Connect

    Finkelman, R.D.; Butler, W.T.

    1985-07-01

    An in vitro model of mineralization was devised in order to study the developmental appearance of dentin gamma-carboxyglutamic acid-containing proteins (DGPs) in relation to the onset of mineralization. Maxillary third molars from 11-day-old rats were cultured with or without fetal calf serum (FCS) as modified from Navia et al. Molars were incubated without radiolabel, or with either /sup 45/CaCl/sub 2/ (5 microCi/ml) for 24 hr at various stages of a ten-day culture period or (/sup 3/H)-leucine (10 microCi/ml) for 24 hr at the eighth day of culture. Molars were lyophilized and extracted with 10% formic acid overnight at 4 degrees C. DGPs in extracts were detected by immunologic and chromatographic techniques; DGPs in molar sections were detected by immunolocalization using indirect immunofluorescence. Molar development was evaluated histologically using the Von Kossa staining technique. Molars cultured with FCS showed histologic evidence for mineralized dentin and enamel and a significant increase in /sup 45/Ca uptake after the sixth day in vitro. Eleven-day-old molars in vivo and molars cultured without FCS showed no evidence of the presence of mineralized tissues. (/sup 3/H)-Leucine-labeled DGPs were isolated and identified by affinity and reversed-phase high-performance liquid chromatography and by gel electrophoresis from both mineralized and unmineralized molars. DGP antigens were localized immunohistochemically using rabbit anti-rat antibodies raised against a highly purified DGP preparation. In the unmineralized molar, antigenicity was seen in odontoblasts but not in predentin matrix, preodontoblasts, or in any other cell type. Antigens in the mineralized molar were localized to odontoblasts and dentin.

  15. Sex determination in modern Greeks using diagonal measurements of molar teeth.

    PubMed

    Zorba, Eleni; Moraitis, Konstantinos; Eliopoulos, Constantine; Spiliopoulou, Chara

    2012-04-10

    Sex determination is a necessary step in the investigation of unidentified human remains from a forensic context. Teeth, as one of the strongest tissues in the human body, can be used for this purpose. Most studies of sexual dimorphism in teeth are based on the traditional mesiodistal and buccolingual crown measurements. The purpose of this study is to examine the degree of sexual dimorphism in permanent molars of modern Greeks using crown and cervical diagonal diameters, and to evaluate their applicability in sex determination. A total of 344 permanent molars in 107 individuals (53 male and 54 female) from the Athens Collection were examined. Crown and cervical diagonal diameters of both maxillary and mandibular molars were measured. It was found that males have larger molars than females and in 19 out of 24 dimensions measured male molars exceeded female molars significantly (P<0.05). The most dimorphic molars are the maxillary second molar, and the mandibular second and first molars. Although other molars were also sexually dimorphic they did not have a statistically significant difference in all dimensions. Cervical diagonal diameters have found to be more sexually diamorphic than crown diagonal diameters. In discriminant function analysis the variables entered more frequently were the cervical diagonal diameters mainly of mandibular molars. Classification accuracy was found to be 93% for the total sample, 77.4% for upper jaw, and 88.4% for the lower jaw. Accuracy rates were higher for cervical than crown diagonal diameters. The data generated from the present study suggest that this metric method can be useful and reliable for sex determination, especially when the traditional dental measurements are not applicable.

  16. Accuracy of Panoramic Radiograph in Assessment of the Relationship Between Mandibular Canal and Impacted Third Molars

    PubMed Central

    Tantanapornkul, Weeraya; Mavin, Darika; Prapaiphittayakun, Jaruthai; Phipatboonyarat, Natnicha; Julphantong, Wanchanok

    2016-01-01

    Background: The relationship between impacted mandibular third molar and mandibular canal is important for removal of this tooth. Panoramic radiography is one of the commonly used diagnostic tools for evaluating the relationship of these two structures. Objectives: To evaluate the accuracy of panoramic radiographic findings in predicting direct contact between mandibular canal and impacted third molars on 3D digital images, and to define panoramic criterion in predicting direct contact between the two structures. Methods: Two observers examined panoramic radiographs of 178 patients (256 impacted mandibular third molars). Panoramic findings of interruption of mandibular canal wall, isolated or with darkening of third molar root, diversion of mandibular canal and narrowing of third molar root were evaluated for 3D digital radiography. Direct contact between mandibular canal and impacted third molars on 3D digital images was then correlated with panoramic findings. Panoramic criterion was also defined in predicting direct contact between the two structures. Results: Panoramic findings of interruption of mandibular canal wall, isolated or with darkening of third molar root were statistically significantly correlated with direct contact between mandibular canal and impacted third molars on 3D digital images (p < 0.005), and were defined as panoramic criteria in predicting direct contact between the two structures. Conclusion: Interruption of mandibular canal wall, isolated or with darkening of third molar root observed on panoramic radiographs were effective in predicting direct contact between mandibular canal and impacted third molars on 3D digital images. Panoramic radiography is one of the efficient diagnostic tools for pre-operative assessment of impacted mandibular third molars. PMID:27398105

  17. Partially integrated exhaust manifold

    SciTech Connect

    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.

  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. Laparoscopic partial splenic resection.

    PubMed

    Uranüs, S; Pfeifer, J; Schauer, C; Kronberger, L; Rabl, H; Ranftl, G; Hauser, H; Bahadori, K

    1995-04-01

    Twenty domestic pigs with an average weight of 30 kg were subjected to laparoscopic partial splenic resection with the aim of determining the feasibility, reliability, and safety of this procedure. Unlike the human spleen, the pig spleen is perpendicular to the body's long axis, and it is long and slender. The parenchyma was severed through the middle third, where the organ is thickest. An 18-mm trocar with a 60-mm Endopath linear cutter was used for the resection. The tissue was removed with a 33-mm trocar. The operation was successfully concluded in all animals. No capsule tears occurred as a result of applying the stapler. Optimal hemostasis was achieved on the resected edges in all animals. Although these findings cannot be extended to human surgery without reservations, we suggest that diagnostic partial resection and minor cyst resections are ideal initial indications for this minimally invasive approach.

  20. 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.

  1. 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

  2. Uniquely derived upper molar morphology of Eocene Amphipithecidae (Primates: Anthropoidea): homology and phylogeny.

    PubMed

    Coster, Pauline; Beard, K Christopher; Soe, Aung Naing; Sein, Chit; Chaimanee, Yaowalak; Lazzari, Vincent; Valentin, Xavier; Jaeger, Jean-Jacques

    2013-08-01

    The extinct Southeast Asian primate family Amphipithecidae is regularly cited in discussions of anthropoid origins, but its phylogenetic position remains controversial. In part, the lack of consensus regarding amphipithecid relationships can be attributed to uncertainty regarding the homology of upper molar structures in this group. Here, we describe a virtually pristine upper molar of Pondaungia cotteri from the late middle Eocene Pondaung Formation of Myanmar, which is the first example of a relatively unworn and well-preserved amphipithecid upper molar ever recovered. The distolingual upper molar cusp in this new specimen of Pondaungia appears to be a lingually displaced and enlarged metaconule, rather than a hypocone or pseudohypocone as previous workers have thought. Reassessment of the upper molar morphology of other amphipithecids and putative amphipithecids reveals a very similar pattern in Siamopithecus, Myanmarpithecus and Ganlea, all of which are interpreted as having upper molars showing many of the same derived features apparent in Pondaungia. In contrast, the upper molar morphology of Bugtipithecus diverges radically from that of undoubted amphipithecids, and the latter taxon is excluded from Amphipithecidae on this basis. Phylogenetic analyses of several character-taxon matrices culled from the recent literature and updated to reflect the new information on amphipithecid upper molar morphology yield similar results. Consensus tree topologies derived from these analyses support amphipithecid monophyly and stable relationships within Amphipithecidae. Amphipithecids appear to be stem members of the anthropoid clade.

  3. 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.

  4. Stainless steel crown bridge replacing permanent molar in the adolescent patient: a case report.

    PubMed

    Dimri, M; Jain, A

    2001-06-01

    The loss of a permanent molar in young adolescent patient creates a need for early space maintenance and restoration of function. To establish function and esthetics short-term treatments include interim restorative approaches. This paper describes a functional, cost-effective stainless steel crown bridge as an interim restoration after the loss of permanent first molar in an early adolescent dentition.

  5. Impacted third molars: a contributing factor in mandibular fractures in contact sports.

    PubMed

    Schwimmer, A; Stern, R; Kritchman, D

    1983-01-01

    Studies have shown that the presence of impacted third molars places the mandible at increased risk for fracture. Individuals participating in high contact sports are subject to maxillofacial trauma; therefore, participants with impacted third molars are at increased risk for fractured mandibles. Three cases are reviewed to illustrate this problem.

  6. Modified distal shoe appliance for premature loss of multiple deciduous molars: a case report.

    PubMed

    Bhat, Prasanna Kumar; K, Navin H; Idris, Mohammed; Christopher, Pradeep; Rai, Niharika

    2014-08-01

    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.

  7. Radiological age estimation: based on third molar mineralization and eruption in Turkish children and young adults.

    PubMed

    Karadayi, Beytullah; Kaya, Ahsen; Kolusayın, Melek Ozlem; Karadayi, Sükriye; Afsin, Hüseyin; Ozaslan, Abdi

    2012-11-01

    Radiographic evaluation of mineralization and eruption stages of third molars using dental panoramic radiographies can be an efficient tool for chronological age estimation in both forensic sciences and legal medicine. The third molar tooth is utilized for dental age estimation about the age span of 15-23 years because it represents the only tooth still in development. The aim of this study is to obtain and analyze data regarding third molar development and eruption in Turkish population for dental age estimation. A total of 744 dental panoramic radiographies of 394 female and 350 male subjects aged between 8 and 22 years were examined. Third molar development was determined according to the Nolla classification system, and eruption was assessed relative to the alveolar bone level. Mandibular and maxillary third molars were generally found at similar stages of development on both sides. Nolla stage 6 (completed crown calcification) was reached at around the age of 15 in both maxillary and mandibular third molars in both sexes. Alveolar emergence was at around the age of 16 in males and around age of 17 in females. Although third molars' eruption shows greater variability than development of third molars, data which were obtained from this study about eruption of these teeth can be supportive to development data for age estimation.

  8. Interactions of glycine betaine with proteins: insights from volume and compressibility measurements.

    PubMed

    Shek, Yuen Lai; Chalikian, Tigran V

    2013-01-29

    We report the first application of volume and compressibility measurements to characterization of interactions between cosolvents (osmolytes) and globular proteins. Specifically, we measure the partial molar volumes and adiabatic compressibilities of cytochrome c, ribonuclease A, lysozyme, and ovalbumin in aqueous solutions of the stabilizing osmolyte glycine betaine (GB) at concentrations between 0 and 4 M. The fact that globular proteins do not undergo any conformational transitions in the presence of GB provides an opportunity to study the interactions of GB with proteins in their native states within the entire range of experimentally accessible GB concentrations. We analyze our resulting volumetric data within the framework of a statistical thermodynamic model in which each instance of GB interaction with a protein is viewed as a binding reaction that is accompanied by release of four water molecules. From this analysis, we calculate the association constants, k, as well as changes in volume, ΔV(0), and adiabatic compressibility, ΔK(S0), accompanying each GB-protein association event in an ideal solution. By comparing these parameters with similar characteristics determined for low-molecular weight analogues of proteins, we conclude that there are no significant cooperative effects involved in interactions of GB with any of the proteins studied in this work. We also evaluate the free energies of direct GB-protein interactions. The energetic properties of GB-protein association appear to scale with the size of the protein. For all proteins, the highly favorable change in free energy associated with direct protein-cosolvent interactions is nearly compensated by an unfavorable free energy of cavity formation (excluded volume effect), yielding a modestly unfavorable free energy for the transfer of a protein from water to a GB/water mixture. PMID:23293944

  9. An evaluation of combination second molar extraction and functional appliance therapy.

    PubMed

    Whitney, E F; Sinclair, P M

    1987-03-01

    The purpose of this study was to examine the results of a treatment regimen involving the extraction of four second molars followed by a combination of sagittal, Bionator, and fixed appliance therapy. The pretreatment and posttreatment cephalometric and dental cast records of 30 consecutively treated Class II, Division 1 cases were evaluated. Results showed that the Class II skeletal correction was achieved by a "headgear" effect inhibiting maxillary growth in conjunction with normal forward mandibular growth. No significant distal bodily movement or tipping of either maxillary or mandibular first molars was found. Significant increases were seen in maxillary arch length, maxillary intercanine and intermolar width, and mandibular intermolar width as a result of treatment. Maxillary third molar position tended to improve following second molar extraction; mandibular third molar changes were more variable.

  10. 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

  11. Early mixed dentition treatment of bilateral impaction of permanent mandibular first molars.

    PubMed

    Wilson Machado, Adre; McComb, Ryan; Wu, Kimberley; Moon, Won

    2013-01-01

    Available scientific literature is scarce in covering cases involving impaction of permanent mandibular first molars treated in mixed dentition patients. The purpose of this report was to present the case of a 7-year-old patient with bilateral impaction of permanent mandibular first molars treated early using a simple and effective removable appliance. The proposed intervention involved the construction of a removable acrylic appliance with bilateral titanium-molybdenum alloy distalizing springs to disimpact and allow complete eruption of the molars. A button was bonded to the occlusal surface of each molar to be used as a leverage point for the distalizing springs. Following seven months of treatment, both the permanent mandibular right and left first molars were upright and in physiologic position. This case demonstrates that, when this problem is identified and treated early, pediatric dentists have the opportunity to minimize the complexity of future orthodontic treatment and limit the extent of malocclusion in the permanent dentition.

  12. First molar eruption in cattle and its use in age determination.

    PubMed

    Andrews, A H

    1980-11-01

    Two studies were undertaken into the intraoral eruption of the first molar in live cattle. The first was a longitudinal survey using monthly observations of Welsh Black bulls and the second involved 300 animals of both sexes and varying breeds, reared under different management systems, using the cross-sectional technique. There were significant differences between the ages at most successive molar codes in both studies. However, a comparison between the two studies showed the mean age at each stage of molar development was higher in the longitudinal study and at three stages this was significant. The age range for each molar code, obtained from the two studies combined, varied between 2.0 and 4.7 months but indicated that the eruption of the first molar tooth was of use in age assessment.

  13. Biodentine Pulpotomy in Mature Permanent Molar: A Case Report

    PubMed Central

    2016-01-01

    Irreversible pulpitis is the most common reason for endodontic treatment in primary and permanent teeth. Root canal therapy and extraction are the two viable and most documented treatment options for the same. Studies with regards to management of mature permanent teeth with carious exposure and treatment with vital pulp therapies such as adult permanent tooth pulpotomy are scarce. However, permanent tooth pulpotomy with the new calcium-silicate based cements (Mineral Trioxide Aggregate and Biodentine) can help preserve the tooth pulp vitality and promote healing and repair foregoing the more invasive root canal therapy procedure. A 12-year old male patient with irreversible pulpitis in right mandibular first permanent molar was treated with complete coronal pulpotomy with placement of Biodentine in the pulp chamber and a full coronal coverage using stainless steel crown. Clinical and radiographic examinations were performed at three, six, twelve and eighteen months. At the end of 18 months, the patient was completely asymptomatic and the tooth was free of any clinical and radiographic signs of inflammation and infection. PMID:27630966

  14. Biodentine Pulpotomy in Mature Permanent Molar: A Case Report

    PubMed Central

    2016-01-01

    Irreversible pulpitis is the most common reason for endodontic treatment in primary and permanent teeth. Root canal therapy and extraction are the two viable and most documented treatment options for the same. Studies with regards to management of mature permanent teeth with carious exposure and treatment with vital pulp therapies such as adult permanent tooth pulpotomy are scarce. However, permanent tooth pulpotomy with the new calcium-silicate based cements (Mineral Trioxide Aggregate and Biodentine) can help preserve the tooth pulp vitality and promote healing and repair foregoing the more invasive root canal therapy procedure. A 12-year old male patient with irreversible pulpitis in right mandibular first permanent molar was treated with complete coronal pulpotomy with placement of Biodentine in the pulp chamber and a full coronal coverage using stainless steel crown. Clinical and radiographic examinations were performed at three, six, twelve and eighteen months. At the end of 18 months, the patient was completely asymptomatic and the tooth was free of any clinical and radiographic signs of inflammation and infection.

  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. Microleakage reduction from newer esthetic restorative materials in permanent molars.

    PubMed

    Ferdianakis, K

    1998-01-01

    Through use of new technologies, such as air-abrasive devices, caries detector dyes, modern technology can increase the speed, comfort and success of dental restorations. However the issue of marginal adaptation has been an ongoing technical problem. Today with the more frequent use of posterior composite resins, poor marginal adaptation of resin is still the major cause of failure of the restoration. Material contraction from polymerization and possibly inappropriate preparation design are key factors in the longevity of the restorations. This study attempts to determine the more effective material and technique for reducing microleakage in composite restorations. An in vitro study using three hybrid composite resins was done to evaluate marginal microleakage. Extracted molars were chosen and evaluated for caries through the use of caries detector dye. Using air-abrasion, caries were removed and minimal preparations were done. The samples were divided into two groups. First group was restored with Herculite XRV and Heliomolar paste composites resins. The second group was restored with Revolution flowable composite resin. Also Opti-bond and Fortify were used as a bonding agent and surface penetrating sealant respectively. The teeth were properly finished, thermocycled and evaluated for leakage using 2% basic fuschin detector dye. All data were subjected to the nonparametric Mann-Whitney Rank Sum Test. The results revealed that Herculite XRV and Heliomolar paste composites had significantly higher microleakage formation (P < 0.03), and also they presented higher void formation (P < 0.0001) than Revolution flowable composite resin.

  17. Biodentine Pulpotomy in Mature Permanent Molar: A Case Report.

    PubMed

    Soni, Harleen Kaur

    2016-07-01

    Irreversible pulpitis is the most common reason for endodontic treatment in primary and permanent teeth. Root canal therapy and extraction are the two viable and most documented treatment options for the same. Studies with regards to management of mature permanent teeth with carious exposure and treatment with vital pulp therapies such as adult permanent tooth pulpotomy are scarce. However, permanent tooth pulpotomy with the new calcium-silicate based cements (Mineral Trioxide Aggregate and Biodentine) can help preserve the tooth pulp vitality and promote healing and repair foregoing the more invasive root canal therapy procedure. A 12-year old male patient with irreversible pulpitis in right mandibular first permanent molar was treated with complete coronal pulpotomy with placement of Biodentine in the pulp chamber and a full coronal coverage using stainless steel crown. Clinical and radiographic examinations were performed at three, six, twelve and eighteen months. At the end of 18 months, the patient was completely asymptomatic and the tooth was free of any clinical and radiographic signs of inflammation and infection. PMID:27630966

  18. 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

  19. Use of opioid pain relievers following extraction of third molars.

    PubMed

    Weiland, Breanna M; Wach, Anthony G; Kanar, Brent P; Castele, Matthew T; Sosovicka, Mark F; Cooke, Matthew R; Moore, Paul A

    2015-02-01

    Following extraction of third molars, it is common practice for oral and maxillofacial surgeons to provide a prescription for an opioid-containing analgesic such as hydrocodone with acetaminophen. Because the instructions for use most often indicate that these analgesics are to be taken "as needed for pain," it is unknown how many of the prescribed postoperative analgesic tablets are needed and actually taken. Therefore, an assessment of patient pain experiences and actual opioid analgesic usage was carried out using structured telephone interviews of patients performed 1 and 7 days following their thirdmolar extraction surgery. Forty-eight adolescents and young adults, ages 15 to 30 years, participated in this assessment. A review of the surgeon's notes indicated that the median number of prescribed opioid-containing analgesics (ie, Vicodin®, Norco®, Lorcet®, Percocet®) was 20 tablets (range 10 to 40). The median consumption during the first 24 hours was reported to be three tablets (range 0 to 10), and the total consumption for all 7 days was eight tablets (range 0 to 34). Four patients reported nausea or vomiting in the first 24 hours, and six patients reported nausea or vomiting during the following 6 days of recovery. The initial prescriptions provided adequate relief for 45 of the 48 patients. Higher consumption of opioid pain relievers (OPRs) was associated with a longer duration of surgery and the occurrence of postoperative infections. PMID:25822637

  20. Conformal Visualization for Partially-Immersive Platforms

    PubMed Central

    Petkov, Kaloian; Papadopoulos, Charilaos; Zhang, Min; Kaufman, Arie E.; Gu, Xianfeng

    2010-01-01

    Current immersive VR systems such as the CAVE provide an effective platform for the immersive exploration of large 3D data. A major limitation is that in most cases at least one display surface is missing due to space, access or cost constraints. This partially-immersive visualization results in a substantial loss of visual information that may be acceptable for some applications, however it becomes a major obstacle for critical tasks, such as the analysis of medical data. We propose a conformal deformation rendering pipeline for the visualization of datasets on partially-immersive platforms. The angle-preserving conformal mapping approach is used to map the 360°3D view volume to arbitrary display configurations. It has the desirable property of preserving shapes under distortion, which is important for identifying features, especially in medical data. The conformal mapping is used for rasterization, realtime raytracing and volume rendering of the datasets. Since the technique is applied during the rendering, we can construct stereoscopic images from the data, which is usually not true for image-based distortion approaches. We demonstrate the stereo conformal mapping rendering pipeline in the partially-immersive 5-wall Immersive Cabin (IC) for virtual colonoscopy and architectural review. PMID:26279083

  1. Dietary Inference from Upper and Lower Molar Morphology in Platyrrhine Primates

    PubMed Central

    Allen, Kari L.; Cooke, Siobhán 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

  2. The extent of axonal exposure and axo-axonal apposition in the non-myelinated nerve fibres of peripheral nerve trunks and their dependence on buffer molarity.

    PubMed

    Holland, G R

    1982-03-01

    Nineteen rats were perfused intracardially with a 2% glutaraldehyde solution in cacodylate buffers adjusted in molarity from 0 to 0 . 4 m. Ultrathin sections of the inferior alveolar nerve were photographed in the electron microscopy. From prints of unmyelinated nerve fibres, the following measurements were made: axon circumference, the proportion of axons which were incompletely covered by the Schwann cell and the extent of this 'exposure', the proportion of axons which were apparently in contact with each other and the extent of this contact and the axon-Schwann cell gap. Axonal size and the spacing between the axon and Schwann cell were not related to buffer molarity. Very few (0-3 . 4%) of the axons were in contact and the degree of contact was unrelated to buffer concentration. Of the axons, 10-34% were partially unsheathed, the proportion being linearly related to the molarity of the buffer vehicle. It is concluded that axo-axonal apposition is an insignificant feature in this nerve trunk, but that axonal exposure is a constant finding although its extent is dependent on the conditions of fixation.

  3. 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.

  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.

  5. Esthetic removable partial dentures.

    PubMed

    Ancowitz, Stephen

    2004-01-01

    This article provides information regarding the many ways that removable partial dentures (RPDs) may be used to solve restorative problems in the esthetic zone without displaying metal components or conspicuous acrylic resin flanges. The esthetic zone is defined and described, as are methods for recording it. Six dental categories are presented that assist the dentist in choosing a variety of RPD design concepts that may be used to avoid metal display while still satisfying basic principles of RPDs. New materials that may be utilized for optimal esthetics are presented and techniques for contouring acrylic resin bases and tinting denture bases are described.

  6. Experts' Understanding of Partial Derivatives Using the Partial Derivative Machine

    ERIC Educational Resources Information Center

    Roundy, David; Weber, Eric; Dray, Tevian; Bajracharya, Rabindra R.; Dorko, Allison; Smith, Emily M.; Manogue, Corinne A.

    2015-01-01

    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…

  7. 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

  8. 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.

  9. Partial Triceps Disruption

    PubMed Central

    Foulk, David M.; Galloway, Marc T.

    2011-01-01

    Partial triceps tendon disruptions are a rare injury that can lead to debilitating outcomes if misdiagnosed or managed inappropriately. The clinician should have a high index of suspicion when the mechanism involves a fall onto an outstretched arm and there is resultant elbow extension weakness along with pain and swelling. The most common location of rupture is at the tendon-osseous junction. This case report illustrates a partial triceps tendon disruption with involvement of, primarily, the medial head and the superficial expansion. Physical examination displayed weakness with resisted elbow extension in a flexed position over 90°. Radiographs revealed a tiny fleck of bone proximal to the olecranon, but this drastically underestimated the extent of injury upon surgical exploration. Magnetic resonance imaging is essential to ascertain the percentage involvement of the tendon; it can be used for patient education and subsequently to determine treatment recommendations. Although excellent at finding associated pathology, it may misjudge the size of the tear. As such, physicians must consider associated comorbidities and patient characteristics when formulating treatment plans. PMID:23016005

  10. Determination of molar IR absorptivities and their errors

    NASA Astrophysics Data System (ADS)

    Staat, H.; Korte, E. H.

    1984-03-01

    Molar absorptivities of band maxima of acetonitrile, n-heptane, benzene, and toluene were determined from difference spectra. The statistical and most important systematic errors are given. Recently, we studied statistical and systematic errors occuring in the determination of IR absorptivities ɛ of liquids (ref. 1). Considerable systematic errors are caused by reflection losses at the outer and inner surfaces of the cell windows. It was shown that these are compensated for if the ratio of two transmittance spectra (T 1, T 2) due to different sample thicknesses (d 1, d 2) is used: In such a case Bouguer—Lambert-Beer's laws leads to ? where c denotes the concentration. The reliability of the absorptivities derived in this way, is mainly affected by the statistical error comprising the standard deviations of the transmittance measurements as well as by the systematic errors from multiple beam interference within the cell (the fringes do not compensate for each other because of their different periods) and from the finite slit width. Experimental conditions can be chosen so that errors from beam convergence, polarization, temperature variations, and thermal emission are negligible. The influences on the transmittance measurement by drift, unwanted radiation, reliability of wavenumber reading, and non-linearity of the detector system are not considered. The molar absorptivities of band maxima of acetonitrile, n-heptane, benzene, and toluene have been determined using equation (1) and are listed in the Table. The values ofΔd employed were in the order of 10 μm to 40 μm, therefore, the strongest bands could not be evaluated. The statistical error was calculated from ? and the systematic error due to finite spectral slit width (s) from ? with the band half-width 2γ. The deviation of the cell from planoparallel shape has been taken into account quantitatively, this is different to the method used previously (ref. 1). If the cell is wedge shaped so that its thickness

  11. 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}

  12. Quantum volume

    NASA Astrophysics Data System (ADS)

    Ryabov, V. A.

    2015-08-01

    Quantum systems in a mechanical embedding, the breathing mode of a small particles, optomechanical system, etc. are far not the full list of examples in which the volume exhibits quantum behavior. Traditional consideration suggests strain in small systems as a result of a collective movement of particles, rather than the dynamics of the volume as an independent variable. The aim of this work is to show that some problem here might be essentially simplified by introducing periodic boundary conditions. At this case, the volume is considered as the independent dynamical variable driven by the internal pressure. For this purpose, the concept of quantum volume based on Schrödinger’s equation in 𝕋3 manifold is proposed. It is used to explore several 1D model systems: An ensemble of free particles under external pressure, quantum manometer and a quantum breathing mode. In particular, the influence of the pressure of free particle on quantum oscillator is determined. It is shown also that correction to the spectrum of the breathing mode due to internal degrees of freedom is determined by the off-diagonal matrix elements of the quantum stress. The new treatment not using the “force” theorem is proposed for the quantum stress tensor. In the general case of flexible quantum 3D dynamics, quantum deformations of different type might be introduced similarly to monopole mode.

  13. Root canal anatomy of mandibular second molars. Part I.

    PubMed

    Manning, S A

    1990-01-01

    The root canal anatomy of 149 mandibular second molars was studied using a technique in which the pulp was removed, the canal space filled with black ink and the roots demineralized and made transparent. Of the 149 teeth, 22 per cent had single roots, 76 per cent had two roots and 2 per cent had three roots. In the single-rooted teeth, three canals were most common, while in the mesial root of the two-rooted teeth, two canals that joined near the apex and one canal in the distal root were most frequent. Round canals were most common in two-rooted teeth and C-shaped canals in single-rooted teeth. Transverse anastomoses were found in 33 per cent of roots, most commonly in the middle third of the root. Lateral canals were found in 72 per cent of roots, most commonly in the apical third of the root. The apical foramen was positioned at the apex in only 33 per cent of roots, and apical deltas were found in 35 per cent. The patient's age and race affected canal shape, with more round canals present in patients over 35 years of age, and more C-shaped canals in Asians. The sex of the patient and the side of the mouth affected the presence of apical deltas, with more being found in males and on the left side. Single-rooted teeth had more complex root canal systems than two-rooted teeth, with more lateral canals, transverse anastomoses, apical deltas and C-shaped canals.

  14. Pulpal responses to cavity preparation in aged rat molars.

    PubMed

    Kawagishi, Eriko; Nakakura-Ohshima, Kuniko; Nomura, Shuichi; Ohshima, Hayato

    2006-10-01

    The dentin-pulp complex is capable of repair after tooth injuries including dental procedures. However, few data are available concerning aged changes in pulpal reactions to such injuries. The present study aimed to clarify the capability of defense in aged pulp by investigating the responses of odontoblasts and cells positive for class II major histocompatibility complex (MHC) to cavity preparation in aged rat molars (300-360 days) and by comparing the results with those in young adult rats (100 days). In untreated control teeth, immunoreactivity for intense heat-shock protein (HSP)-25 and nestin was found in odontoblasts, whereas class-II-MHC-positive cells were densely distributed in the periphery of the pulp. Cavity preparation caused two types of pulpal reactions based on the different extent of damage in the aged rats. In the case of severe damage, destruction of the odontoblast layer was conspicuous at the affected site. By 12 h after cavity preparation, numerous class-II-MHC-positive cells appeared along the pulp-dentin border but subsequently disappeared together with HSP-25-immunopositive cells, and finally newly differentiated odontoblast-like cells took the place of the degenerated odontoblasts and acquired immunoreactivity for HSP-25 and nestin by postoperative day 3. In the case of mild damage, no remarkable changes occurred in odontoblasts after operation, and some survived through the experimental stages. These findings indicate that aged pulp tissue still possesses a defense capacity, and that a variety of reactions can occur depending on the difference in the status of dentinal tubules and/or odontoblast processes in individuals.

  15. Mass or molar? Recommendations for reporting concentrations of therapeutic drugs.

    PubMed

    Jones, Graham R D; Bryant, Stewart; Fullinfaw, Robert; Ilett, Ken; Miners, John O; Morris, Raymond G; Doogue, Matthew P

    2013-04-15

    A working party (WP) from the Australasian Association of Clinical Biochemists, Australasian Society of Clinical and Experimental Pharmacologists and Toxicologists, Royal College of Pathologists of Australasia and Royal Australasian College of Physicians recommends the following: *mass units should be used for reporting therapeutic drug concentrations in Australia and New Zealand; and the litre (L) should be used as the denominator when expressing concentration. Examples of these units are mg/L and μg/L Exceptions to these principles include: *drugs for which there is current uniformity of reporting and supporting information using molar units, notably lithium (mmol/L) and methotrexate (μmol/L); *drugs that are also present as endogenous substances, where the units used routinely should continue to be used. This applies to many substances, including minerals (eg, iron; μmol/L), vitamins (eg, vitamin D; nmol/L) and hormones (eg, thyroxine; pmol/L). *drugs for which the denominator is not a 198 of fluid and there is international uniformity of reporting (eg, thiopurine metabolites; per 109 red blood cells). These recommendations relate to drugs that are used therapeutically, whether measured for therapeutic drug monitoring purposes or for assessment of overdose. Other substances, such as drugs of misuse, heavy metals or environmental toxins, were not considered by the WP and are thus not covered by this document. These recommendations should also be applied to other supporting documentation such as published guidelines, journal articles and websites. The implementation of these recommendations in New Zealand is subject to local confirmation. PMID:23581955

  16. Morphometric variation of extant platyrrhine molars: taxonomic implications for fossil platyrrhines

    PubMed Central

    Nova Delgado, Mónica; Galbany, Jordi

    2016-01-01

    The phylogenetic position of many fossil platyrrhines with respect to extant ones is not yet clear. Two main hypotheses have been proposed: the layered or successive radiations hypothesis suggests that Patagonian fossils are Middle Miocene stem platyrrhines lacking modern descendants, whereas the long lineage hypothesis argues for an evolutionary continuity of all fossil platyrrhines with the extant ones. Our geometric morphometric analysis of a 15 landmark-based configuration of platyrrhines’ first and second lower molars suggest that morphological stasis may explain the reduced molar shape variation observed. Platyrrhine lower molar shape might be a primitive retention of the ancestral state affected by strong ecological constraints throughout the radiation of the main platyrrhine families. The Patagonian fossil specimens showed two distinct morphological patterns of lower molars, Callicebus—like and Saguinus—like, which might be the precursors of the extant forms, whereas the Middle Miocene specimens, though showing morphological resemblances with the Patagonian fossils, also displayed new, derived molar patterns, Alouatta—like and Pitheciinae—like, thereby suggesting that despite the overall morphological stasis of molars, phenotypic diversification of molar shape was already settled during the Middle Miocene. PMID:27190704

  17. The effects of sandblasting on the bond strength of molar attachments--an in vitro study.

    PubMed

    Johnston, C D; McSherry, P F

    1999-06-01

    This study evaluated the effect of sandblasting foil mesh molar tube bases on the shear bond strength obtained when bonding to first molar teeth. Fifty-two recently extracted first molar teeth were etched with 35 per cent phosphoric acid gel for 30 seconds. Twenty-six sandblasted 'A' Company molar tube attachments and 26 non-sandblasted attachments were then bonded to the teeth using Phase II orthodontic bonding resin. After storage in water for 24 hours at 37 degrees C, the specimens were debonded in a direction parallel to the buccal surface. Survival analysis using the Weibull function revealed that for a 90 per cent probability of survival, the predicted bond strengths for sandblasted and non-sandblasted bases were 1.76 and 1.66 MPa, respectively. For larger shear stresses, the probabilities of bond survival with sandblasted molar tubes were greater than with non-sandblasted molar tubes although the differences were small, which may be explained by the large proportion of bond failures which occurred at the resin to enamel interface in both groups. It was concluded that sandblasting foil mesh bases is likely to provide only a minimal improvement in clinical performance when bonding to molar teeth. PMID:10407540

  18. 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

  19. Ectopic Molar Pregnancy: Diagnostic Efficacy of Magnetic Resonance Imaging and Review of the Literature

    PubMed Central

    Yamada, Yasushi; Yamazaki, Teruyuki; Shiozawa, Tanri

    2016-01-01

    Ectopic molar pregnancy is extremely rare, and preoperative diagnosis is difficult. Our literature search found only one report of molar pregnancy diagnosed preoperatively. Moreover, there is no English literature depicting magnetic resonance image (MRI) findings of ectopic molar pregnancy. We report a case of ectopic molar pregnancy preoperatively diagnosed using MRI. A literature review of 31 cases of ectopic molar pregnancy demonstrated that lesions have been found in the fallopian tube (19 cases, 61%), ovary (5 cases, 16%), cornu (3 cases, 10%), peritoneum (2 cases, 6%), uterine cervix (1 case, 3%), and cesarean scar (1 case, 3%). Abdominal pain and abnormal vaginal bleeding were reported in 70% and 61% of the patients, respectively. Twenty-one cases (67%) presented with rupture and hemoperitoneum. All patients underwent surgical resection or dilatation and curettage. Methotrexate therapy was performed in one case because residual trophoblastic tissue was suspected. A second operation was performed in one case of ovarian molar pregnancy because serum hCG levels increased again after primary focal ovarian resection. No patients developed metastatic disease or relapsed. These findings suggest the prognosis of ectopic molar pregnancy to be favorable. PMID:27648323

  20. Ectopic Molar Pregnancy: Diagnostic Efficacy of Magnetic Resonance Imaging and Review of the Literature.

    PubMed

    Yamada, Yasushi; Ohira, Satoshi; Yamazaki, Teruyuki; Shiozawa, Tanri

    2016-01-01

    Ectopic molar pregnancy is extremely rare, and preoperative diagnosis is difficult. Our literature search found only one report of molar pregnancy diagnosed preoperatively. Moreover, there is no English literature depicting magnetic resonance image (MRI) findings of ectopic molar pregnancy. We report a case of ectopic molar pregnancy preoperatively diagnosed using MRI. A literature review of 31 cases of ectopic molar pregnancy demonstrated that lesions have been found in the fallopian tube (19 cases, 61%), ovary (5 cases, 16%), cornu (3 cases, 10%), peritoneum (2 cases, 6%), uterine cervix (1 case, 3%), and cesarean scar (1 case, 3%). Abdominal pain and abnormal vaginal bleeding were reported in 70% and 61% of the patients, respectively. Twenty-one cases (67%) presented with rupture and hemoperitoneum. All patients underwent surgical resection or dilatation and curettage. Methotrexate therapy was performed in one case because residual trophoblastic tissue was suspected. A second operation was performed in one case of ovarian molar pregnancy because serum hCG levels increased again after primary focal ovarian resection. No patients developed metastatic disease or relapsed. These findings suggest the prognosis of ectopic molar pregnancy to be favorable. PMID:27648323

  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. Organ culture study of effect of vitamin-A-deficiency on rat third molar development.

    PubMed

    Navia, J M; Snider, C; Punyasingh, J; Harris, S S

    1984-01-01

    A culture procedure for rat third molars suitable for nutritional-developmental studies is described. Unerupted third molars from 12-day-old rats were cultured in BGJb media containing 20 per cent rat serum and supplemented with 25 mM HEPES buffer, 25 mg ascorbic acid, 20 mg L-glutamine, 12 mg penicillin G and 10 mg streptomycin sulphate per 100 ml of media. Molars were cultured at the liquid-gas interphase using a 50 per cent O2, 45 per cent N2, 5 per cent CO2 gas mixture at 10 lb-psig (pounds per square inch guage). Molar cultures were maintained successfully for 9-14 days without evidence of necrosis, although they developed at a slower rate than in vivo. Molars cultured in 50 per cent O2 compared to those cultured in 21 per cent O2 for periods of 2, 4, 6 and 8 days had higher values for protein, alkaline phosphatase (AP), Ca, P and Ca/P. Vitamin-A-deficiency gave lower values for AP, Ca, P, Ca/P, 45Ca, 35S and [14C]-proline uptake. Histologically, A - molars had atrophic ameloblasts, some foci of squamous metaplasia and abnormal keratin formation. Thus, deficiency of vitamin A imposed during in-vitro development of rat third molars retarded dentinogenesis and interfered with early mineralization of enamel and dentine.

  3. Ectopic Molar Pregnancy: Diagnostic Efficacy of Magnetic Resonance Imaging and Review of the Literature

    PubMed Central

    Yamada, Yasushi; Yamazaki, Teruyuki; Shiozawa, Tanri

    2016-01-01

    Ectopic molar pregnancy is extremely rare, and preoperative diagnosis is difficult. Our literature search found only one report of molar pregnancy diagnosed preoperatively. Moreover, there is no English literature depicting magnetic resonance image (MRI) findings of ectopic molar pregnancy. We report a case of ectopic molar pregnancy preoperatively diagnosed using MRI. A literature review of 31 cases of ectopic molar pregnancy demonstrated that lesions have been found in the fallopian tube (19 cases, 61%), ovary (5 cases, 16%), cornu (3 cases, 10%), peritoneum (2 cases, 6%), uterine cervix (1 case, 3%), and cesarean scar (1 case, 3%). Abdominal pain and abnormal vaginal bleeding were reported in 70% and 61% of the patients, respectively. Twenty-one cases (67%) presented with rupture and hemoperitoneum. All patients underwent surgical resection or dilatation and curettage. Methotrexate therapy was performed in one case because residual trophoblastic tissue was suspected. A second operation was performed in one case of ovarian molar pregnancy because serum hCG levels increased again after primary focal ovarian resection. No patients developed metastatic disease or relapsed. These findings suggest the prognosis of ectopic molar pregnancy to be favorable.

  4. 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.

  5. Laparoscopic partial nephrectomy in a horseshoe kidney.

    PubMed

    Molina, Wilson R; Gill, Inderbir S

    2003-12-01

    A 68-year-old man with an incidentally found 2-cm complex enhancing cystic right renal mass in the right moiety of a horseshoe kidney was treated with a three-port retroperitoneal laparoscopic approach. The tumor was completely excised with cold Endoshears, and Surgicel bolsters were tightly buttressed into the resection bed with 0 Vicryl sutures. The warm ischemia time was 31 minutes. To our knowledge, this is the initial case of retroperitoneal laparoscopic partial nephrectomy in a horseshoe kidney. Three-dimensional CT with volume rendering in a video format provides the necessary information about the number, location, and extrarenal anatomy of the renal artery and vein.

  6. Comprehensive Microstructure and Molar Mass Analysis of Polybutadiene by Multidimensional Liquid Chromatography.

    PubMed

    Maiko, Khumo; Pasch, Harald

    2015-12-01

    For the first time, polybutadiene is separated according to microstructure using solvent gradient interaction chromatography (SGIC). Superior separation of polybutadienes having different microstructures is obtained on a silica-based reversed stationary phase and a mobile phase of acetone-hexane. This SGIC system enables the baseline separation of 1,2-polybutadienes and 1,4-polybutadienes even in cases where the samples have similar molar masses. 2D liquid chromatography is performed with the SGIC method separating according to microstructure in the first dimension coupled to size exclusion chromatography separating according to molar mass in the second dimension, thus providing comprehensive information on both microstructure and molar mass.

  7. 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

  8. Comprehensive Microstructure and Molar Mass Analysis of Polybutadiene by Multidimensional Liquid Chromatography.

    PubMed

    Maiko, Khumo; Pasch, Harald

    2015-12-01

    For the first time, polybutadiene is separated according to microstructure using solvent gradient interaction chromatography (SGIC). Superior separation of polybutadienes having different microstructures is obtained on a silica-based reversed stationary phase and a mobile phase of acetone-hexane. This SGIC system enables the baseline separation of 1,2-polybutadienes and 1,4-polybutadienes even in cases where the samples have similar molar masses. 2D liquid chromatography is performed with the SGIC method separating according to microstructure in the first dimension coupled to size exclusion chromatography separating according to molar mass in the second dimension, thus providing comprehensive information on both microstructure and molar mass. PMID:26461063

  9. 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

  10. A New Orthodontic Appliance with a Mini Screw for Upper Molar Distalization

    PubMed Central

    2016-01-01

    The aim of this study is to present a new upper molar distalization appliance called Cise distalizer designed as intraoral device supported with orthodontic mini screw for upper permanent molar distalization. The new appliance consists of eight main components. In order to understand the optimum force level, the appliance under static loading is tested by using strain gage measurement techniques. Results show that one of the open coils produces approximately 300 gr distalization force. Cise distalizer can provide totally 600 gr distalization force. This range of force level is enough for distalization of upper first and second molar teeth. PMID:27528796

  11. 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

  12. Initial tooth movement under extraoral force and considerations for controlled molar movement.

    PubMed

    Yoshida, N; Jost-Brinkmann, P G; Yamada, Y

    1995-01-01

    Initial movement of the maxillary first molars under the application of straight-pull, cervical-pull, and high-pull headgear was measured in human subjects. Facebow deflection can influence molar movement as the relationship of the force vector to the molar's center of resistance changes with an increase of force. The present study proposes using headgear with a combination of variable-pull headcap and short outer bow. A variable-pull headcap allows a great range in force direction. The direction of the headgear force system can be accurately determined using a short outer bow.

  13. Endodontic therapy of a mandibular third molar with 5 canals: a case report.

    PubMed

    Silberman, Adrian; Heilborn, Carlos; Cohenca, Nestor

    2009-06-01

    Endodontic treatment of third molars often becomes part of comprehensive treatment plans, as it represents a more conservative and less invasive approach than its therapeutic alternatives. The frequency of anatomic variations in mandibular molars, particularly root canal configuration, requires 2 periapical radiographs from different angles. Upon reading and interpretation of the radiographs, the clinician should consider the anatomy and level of difficulty of the endodontic procedure and refer the patient to an endodontist, if deemed necessary. The present article discusses the successful treatment and preservation of a mandibular third molar with 5 root canals, as well as methods for its clinical management.

  14. Morphological and anthropological aspects of human triangular deciduous lower first molar teeth.

    PubMed

    Kitagawa, Y; Manabe, Y; Oyamada, J; Rokutanda, A

    1996-04-01

    The crown and root morphology, and bilateral occurrence of human deciduous lower first molars that exhibited a triangular occlusal outline, taken from excavated samples of Japanese, Jomonese and Iraqi origin, were investigated. The crowns of triangular teeth had smaller mesiodistal and larger buccolingual diameters than normally shaped deciduous lower first molars. An elongated buccolingual diameter was derived from the buccal projection of the distobuccal cusp and lingual projection of the portion between the metaconid and distolingual cusp. In this analysis, all triangular deciduous lower first molars in which root morphology could be observed were accompanied by additional distolingual roots. Correlation between the right- and left-hand sides of this trait was high.

  15. Molar pregnancy--associated ectopic decidua: report of a case and review of the literature.

    PubMed

    Kularbkaew, C; Yutanawiboonchai, W; Pairojkul, C

    1998-11-01

    Ectopic or extrauterine decidual transformation is regularly associated with pregnancy. This phenomenon has been observed most often in the ovary and cervix. Sporadic reports have documented decidua formation of peritoneal surfaces, lymph nodes and other organs in pelvic and abdominal cavity. Molar pregnancy-associated ectopic decidua has never been documented. We report the case of ectopic decidua at posterior surface of uterus, near the cul de sac, in a 45-year-old woman with molar pregnancy. The article review reveals that it is the first report of molar pregnancy-associated ectopic decidua. PMID:9803093

  16. Vital Pulp Therapy with Three Different Pulpotomy Agents in Immature Molars: A Case Report

    PubMed Central

    Harandi, Azadeh; Forghani, Maryam; Ghoddusi, Jamileh

    2013-01-01

    Introduction This case report describes apexogenesis treatment of three molar teeth of an 8-year-old boy using three different pulpotomy agents. Methods Pulpotomy was performed on decayed immature molar teeth with established irreversible pulpitis and the remaining pulp was capped with either zinc oxide eugenol, ProRoot mineral trioxide aggregate or calcium-enriched mixture (CEM) cement. Teeth were restored with stainless steel crowns. Results Eighteen months clinical and radiographic follow-up revealed successful preservation of pulpal vitality with continued root development in all treated teeth. Conclusion Based on this case report, CEM cement may be an alternative option for pulpotomy treatment of immature permanent molars. PMID:23922578

  17. 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.

  18. Partially segmented deformable mirror

    DOEpatents

    Bliss, Erlan S.; Smith, James R.; Salmon, J. Thaddeus; Monjes, Julio A.

    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.

  19. Robot-assisted partial nephrectomy: Superiority over laparoscopic partial nephrectomy.

    PubMed

    Shiroki, Ryoichi; Fukami, Naohiko; Fukaya, Kosuke; Kusaka, Mamoru; Natsume, Takahiro; Ichihara, Takashi; Toyama, Hiroshi

    2016-02-01

    Nephron-sparing surgery has been proven to positively impact the postoperative quality of life for the treatment of small renal tumors, possibly leading to functional improvements. Laparoscopic partial nephrectomy is still one of the most demanding procedures in urological surgery. Laparoscopic partial nephrectomy sometimes results in extended warm ischemic time and severe complications, such as open conversion, postoperative hemorrhage and urine leakage. Robot-assisted partial nephrectomy exploits the advantages offered by the da Vinci Surgical System to laparoscopic partial nephrectomy, equipped with 3-D vision and a better degree in the freedom of surgical instruments. The introduction of the da Vinci Surgical System made nephron-sparing surgery, specifically robot-assisted partial nephrectomy, safe with promising results, leading to the shortening of warm ischemic time and a reduction in perioperative complications. Even for complex and challenging tumors, robotic assistance is expected to provide the benefit of minimally-invasive surgery with safe and satisfactory renal function. Warm ischemic time is the modifiable factor during robot-assisted partial nephrectomy to affect postoperative kidney function. We analyzed the predictive factors for extended warm ischemic time from our robot-assisted partial nephrectomy series. The surface area of the tumor attached to the kidney parenchyma was shown to significantly affect the extended warm ischemic time during robot-assisted partial nephrectomy. In cases with tumor-attached surface area more than 15 cm(2) , we should consider switching robot-assisted partial nephrectomy to open partial nephrectomy under cold ischemia if it is imperative. In Japan, a nationwide prospective study has been carried out to show the superiority of robot-assisted partial nephrectomy to laparoscopic partial nephrectomy in improving warm ischemic time and complications. By facilitating robotic technology, robot-assisted partial nephrectomy

  20. 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

  1. A rare presentation of dens in dente in the mandibular third molar with extra oral sinus

    PubMed Central

    Bansal, Monika; Singh, NN; Singh, Anand Pratap

    2010-01-01

    The unusual case of dense in dente in mandibular molar area with extra oral sinus in a 30-year-old female is presented. The chief complaint of the patient was wound formation and pus discharge from the right side of lower jaw for many years. Clinical examination revealed extra oral sinus and mild swelling in vestibular region opposite the right mandibular molars. On radiographical examination, right mandibular third molar had bulbous root associated with periapical radiolucency. It appeared that there was a tooth within a tooth and the invagination extended nearly to the root apex. A clinical diagnosis of dense in dente Type III was confirmed by stereomicroscopy of ground section of the tooth. Extra oral sinus healed after extraction of the mandibular third molar within a month. PMID:21731269

  2. Modification of sagittal split ramus osteotomy to avoid unfavorable fracture around impacted third molars.

    PubMed

    Marquez, I M; Stella, J P

    1998-01-01

    The dental literature recognizes that performing sagittal ramus osteotomy when impacted third molars are present significantly increases the risk of unfavorable fractures of both the proximal and distal segments. Many articles have described how to repair unfavorable fractures of sagittal split segments, but few to date specifically address how to modify the osteotomy design to reduce the potential for unfavorable fractures. Moreover, techniques for removal of impacted third molars after the completion of a sagittal split ramus osteotomy have received little attention in the literature, yet it is obviously a common occurrence. This paper describes a modification of the sagittal split ramus osteotomy when a fully formed impacted third molar is present at the time of the sagittal ramus osteotomy. A technique is also described for removing the impacted third molar after the sagittal split is completed. Clinical experience has demonstrated these techniques to have several advantages.

  3. Management of Chronic Hyperplastic Pulpitis in Mandibular Molars of Middle Aged Adults- A Multidisciplinary Approach.

    PubMed

    Anilkumar, Kanakamedala; 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

  4. 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

  5. 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)

  6. How Many Digits Should We Use in Formula or Molar Mass Calculations?

    ERIC Educational Resources Information Center

    Svensson, Christer

    2004-01-01

    The calculations of uncertainties in the formula or molar masses of compounds are streamlined. Three rules of increasing complexity are proposed, which overestimate the uncertainty so there is little if any risk that the true values are missed.

  7. 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

  8. Third molar development: evaluation of nine tooth development registration techniques for age estimations.

    PubMed

    Thevissen, Patrick W; Fieuws, Steffen; Willems, Guy

    2013-03-01

    Multiple third molar development registration techniques exist. Therefore the aim of this study was to detect which third molar development registration technique was most promising to use as a tool for subadult age estimation. On a collection of 1199 panoramic radiographs the development of all present third molars was registered following nine different registration techniques [Gleiser, Hunt (GH); Haavikko (HV); Demirjian (DM); Raungpaka (RA); Gustafson, Koch (GK); Harris, Nortje (HN); Kullman (KU); Moorrees (MO); Cameriere (CA)]. Regression models with age as response and the third molar registration as predictor were developed for each registration technique separately. The MO technique disclosed highest R(2) (F 51%, M 45%) and lowest root mean squared error (F 3.42 years; M 3.67 years) values, but differences with other techniques were small in magnitude. The amount of stages utilized in the explored staging techniques slightly influenced the age predictions.

  9. The effect of cellulose molar mass on the properties of palmitate esters.

    PubMed

    Willberg-Keyriläinen, Pia; Talja, Riku; Asikainen, Sari; Harlin, Ali; Ropponen, Jarmo

    2016-10-20

    Nowadays one of the growing trends is to replace oil-based products with cellulose-based materials. Currently most cellulose esters require a huge excess of chemicals and have therefore, not been broadly used in the industry. Here, we show that decreasing the molar mass of cellulose by ozone hydrolysis provides cellulose functionalization with less chemical consumption. To reveal the differences in reactivity and chemical consumption, we showed esterification of both native cellulose and ozone treated hydrolyzed cellulose. Based on the results, the molar mass of the starting cellulose has a significant effect on the end product's degree of substitution and properties. Furthermore, molar mass controlled palmitate esters form mechanically strong, flexible and optically transparent films with excellent water barrier properties. We anticipate that molar mass controlled cellulose will provide a starting point for the greater use of cellulose based materials, in various application, such as films and composites. PMID:27474646

  10. 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

  11. Periodontal healing after impacted lower third molar surgery in adolescents and adults. A prospective study.

    PubMed

    Kugelberg, C F; Ahlström, U; Ericson, S; Hugoson, A; Kvint, S

    1991-02-01

    The effects of impacted lower 3rd molar surgery on periodontal tissues in the adjacent 2nd molar area have been investigated in a prospective study comprising 176 cases from 2 age groups: less than or equal to 20 years (n = 93) and greater than or equal to 30 years (n = 83), respectively. The preoperative and 1-year postoperative examinations included both clinical and radiographic variables. All patients were subjected to a standardized surgical procedure and optimal plaque control pre-, intra- and postoperatively. Early removal of impacted lower 3rd molars with large angulation and close positional relationship to the adjacent 2nd molar proved to have a beneficial effect on periodontal health. PMID:2019777

  12. 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.

  13. Partially supervised speaker clustering.

    PubMed

    Tang, Hao; Chu, Stephen Mingyu; Hasegawa-Johnson, Mark; Huang, Thomas S

    2012-05-01

    Content-based multimedia indexing, retrieval, and processing as well as multimedia databases demand the structuring of the media content (image, audio, video, text, etc.), one significant goal being to associate the identity of the content to the individual segments of the signals. In this paper, we specifically address the problem of speaker clustering, the task of assigning every speech utterance in an audio stream to its speaker. We offer a complete treatment to the idea of partially supervised speaker clustering, which refers to the use of our prior knowledge of speakers in general to assist the unsupervised speaker clustering process. By means of an independent training data set, we encode the prior knowledge at the various stages of the speaker clustering pipeline via 1) learning a speaker-discriminative acoustic feature transformation, 2) learning a universal speaker prior model, and 3) learning a discriminative speaker subspace, or equivalently, a speaker-discriminative distance metric. We study the directional scattering property of the Gaussian mixture model (GMM) mean supervector representation of utterances in the high-dimensional space, and advocate exploiting this property by using the cosine distance metric instead of the euclidean distance metric for speaker clustering in the GMM mean supervector space. We propose to perform discriminant analysis based on the cosine distance metric, which leads to a novel distance metric learning algorithm—linear spherical discriminant analysis (LSDA). We show that the proposed LSDA formulation can be systematically solved within the elegant graph embedding general dimensionality reduction framework. Our speaker clustering experiments on the GALE database clearly indicate that 1) our speaker clustering methods based on the GMM mean supervector representation and vector-based distance metrics outperform traditional speaker clustering methods based on the “bag of acoustic features” representation and statistical

  14. Phylogenetic and environmental components of morphological variation: skull, mandible, and molar shape in marmots (Marmota, Rodentia).

    PubMed

    Caumul, Radhekshmi; Polly, P David

    2005-11-01

    The phenotype is a product of its phylogenetic history and its recent adaptation to local environments, but the relative importance of the two factors is controversial. We assessed the effects of diet, habitat, elevation, temperature, precipitation, body size, and mtDNA genetic divergence on shape variation in skulls, mandibles, and molars, structures that differ in their genetic and functional control. We asked whether these structures have adapted to environment to the same extent and whether they retain the same amount of phylogenetic signal. We studied these traits in intra- and interspecific populations of Eurasian marmots whose last common ancestor lived 2-5 million years ago. Path Analysis revealed that body size explained 10% of variation in skulls, 7% in mandibles, and 15% in molars. Local vegetation explained 7% of variation in skulls, 11% in mandibles, and 12% in molars. Dietary category explained 25% of variation in skulls, 11% in mandibles, and 9% in molars. Cyt b mtDNA divergence (phylogeny) explained 15% of variation in skulls, 7% in mandibles, and 5% in molars. Despite the percentages of phylogenetic variance, maximum-likelihood trees based on molar and skull shape recovered most phylogenetic groupings correctly, but mandible shape did not. The good performance of molars and skulls was probably due to different factors. Skulls are genetically and functionally more complicated than teeth, and they had more mathematically independent components of variation (5-6-in skulls compared to 3-in molars). The high proportion of diet-related variance was not enough to mask the phylogenetic signal. Molars had fewer independent components, but they also have less ecophenotypic variation and evolve more slowly, giving each component a proportionally stronger phylogenetic signal. Molars require larger samples for each operational taxonomic unit than the other structures because the proportion of within-taxon to between-taxon variation was higher. Good phylogenetic

  15. Shear bond strength of partial coverage restorations to dentin

    PubMed Central

    Agustín-Panadero, Rubén; Alonso-Pérez-Barquero, Jorge; Fons-Font, Antonio; Solá-Ruíz, María-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=35.27±8.02 MPa; C=36.23±11.23 MPa; OM=28.61±6.27 MPa; CM=27.01±7.57 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

  16. Calculating excess volumes of binary solutions with allowance for structural differences between mixed components

    NASA Astrophysics Data System (ADS)

    Balankina, E. S.

    2016-06-01

    Analytical dependences of a volume's properties on the differences between the geometric structures of initial monosystems are obtained for binary systems simulated by a grain medium. The effect of microstructural parameter k (the ratio of volumes of molecules of mixed components) on the concentration behavior of the relative excess molar volume of different types of real binary solutions is analyzed. It is established that the contribution due to differences between the volumes of molecules and coefficients of the packing density of mixed components is ~80-100% for mutual solutions of n-alkanes and ~55-80% of the experimental value of the relative excess molar volume for water solutions of n-alcohols.

  17. Third molars in the establishment of adult status--a case report.

    PubMed

    Nambiar, P; Yaacob, H; Menon, R

    1996-12-01

    Teeth are the most durable structures in the human body. The timing and sequence of their development, as contained in dental development charts, have been used as valid criteria for age determination. The third molars however are the last teeth to erupt and are regarded as the most variable in the dentition. Age estimation in a legal context, using developing third molars must be carefully applied otherwise justice may miscarry. A case of wrongful use of the technique is presented here.

  18. Root Canal Therapy of a Mandibular First Molar with Five Root Canals: A Case Report

    PubMed Central

    Reyhani, Mohammad Frough; Rahimi, Saeed; Shahi, Shahriar

    2007-01-01

    A mandibular first molar requiring root canal therapy was found with five canals, three mesial canals, and two distal canals. Initially, four canals (mesiobuccal, mesiolingual, distobuccal, and distolingual) were identified. The mesiobuccal and mesiolingual canals were found in their normal locations, and a fifth canal was noted between these two. This case demonstrates a rare anatomical configuration and supplements previous reports of the existence of such configurations in mandibular first molars. PMID:24298291

  19. 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

  20. 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

  1. Unilateral Maxillary First Molar Extraction in Class II Subdivision: An Unconventional Treatment Alternative

    PubMed Central

    Booij, J. W.; Livas, Christos

    2016-01-01

    The asymmetrical intra-arch relationship in Class II subdivision malocclusion poses challenges in the treatment planning and mechanotherapy of such cases. This case report demonstrates a treatment technique engaging unilateral extraction of a maxillary first molar and Begg fixed appliances. The outcome stability and the enhancing effect on the eruption of the third molar in the extraction segment were confirmed by a 4-year follow-up examination. PMID:27200194

  2. 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.

  3. Maxillary first Molar with three canal orifices in MesioBuccal root.

    PubMed

    Ayranci, Leyla B; Arslan, Hakan; Topcuoglu, H Sinan

    2011-10-01

    The present case describes root canal treatment in a maxillary first molar with unusual anatomy. A male patient was referred for the treatment of maxillary left first molar tooth. Clinical examination of the pulpal floor revealed 3 orifices in the mesio buccal root. The tooth was treated successfully. Anatomic variations must be taken into consideration in clinical and radiographic evaluation during endodontic treatment. PMID:22144820

  4. Maxillary first Molar with three canal orifices in MesioBuccal root

    PubMed Central

    Ayranci, Leyla B.; Arslan, Hakan; Topcuoglu, H Sinan

    2011-01-01

    The present case describes root canal treatment in a maxillary first molar with unusual anatomy. A male patient was referred for the treatment of maxillary left first molar tooth. Clinical examination of the pulpal floor revealed 3 orifices in the mesio buccal root. The tooth was treated successfully. Anatomic variations must be taken into consideration in clinical and radiographic evaluation during endodontic treatment PMID:22144820

  5. Alternative approach to management of early loss of second primary molar: a clinical case report.

    PubMed

    Agarwal, Ravi; Chaudhry, Kalpna; Yeluri, Ramakrishna; Singh, Chanchal; Munshi, Autar K

    2014-05-01

    Preservation of space after premature loss of the second primary molar is essential to prevent mesial drifting of the permanent first molar. Various modifications of distal shoe space maintainers, which have been documented, are all nonfunctional in nature. This paper describes an innovative design of a functional distal shoe space maintainer that is intended to overcome the disadvantages of conventional non-functional space maintainers and that does not hamper the periodontal status of the abutment tooth.

  6. 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

  7. 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

  8. 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

  9. 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

  10. Combined treatment with headgear and the Frog appliance for maxillary molar distalization: a randomized controlled trial

    PubMed Central

    2013-01-01

    Objective To evaluate the efficiency of the Frog appliance (FA) alone or in combination with headgear for distalizing the maxillary molars. Methods Fifty patients (25 males and 25 females) aged 12.6 - 16.7 years who received treatment for Class II malocclusion at the Orthodontic Clinic of Al-Baath University were selected for this study and randomly divided into 2 equal groups. Maxillary molar distalization was achieved using the FA alone (group 1) or a combination of the FA with high-pull headgear worn at night (group 2). Lateral cephalograms were obtained before and after treatment. Results The maxillary molars moved distally by 5.51 and 5.93 mm in groups 1 and 2, respectively. Distal movements were associated with axial tipping by 4.96° and 1.25°, and with loss of anchorage by mesial movement of the second maxillary premolars by 2.70 and 0.90 mm in groups 1 and 2, respectively. The combined use of the FA and nighttime high-pull headgear decreased the distalization time and improved the ratio of maxillary molar distalization movement relative to the overall opening space between the first maxillary molars and second premolars. Conclusions The FA can effectively distalize the maxillary molars, this distalization associates with some unfavorable changes. Nighttime use of high-pull headgear combined with the FA can reduce these unfavorable changes and improve treatment outcomes. PMID:23671835

  11. Prevalence of Third Molar Agenesis: Associated Dental Anomalies in Non-Syndromic 5923 Patients

    PubMed Central

    Sujon, Mamun Khan; Alam, Mohammad Khursheed; Rahman, Shaifulizan Abdul

    2016-01-01

    The aim of this study was to investigate the prevalence of third molar agenesis and other associated dental anomalies in Bangladeshi population and to investigate the relationship of other dental anomalies with the third molar presence/agenesis. A retrospective study was performed using panoramic radiographs of 5923 patients, who ranged in age from 10 to 50 years. All radiographs were analyzed by Planmeca Romexis® 3.0 software (Planmeca Oy, Helsinki, Finland). Pearson chi-square and one way ANOVA (Post Hoc) test were conducted. The prevalence of third molar agenesis was 38.4%. The frequency of third molar agenesis was significantly higher in females than males (p <0.025). Third molar agenesis was significantly more prevalent in maxilla as compared to mandible (p <0.007). The prevalence of other dental anomalies was 6.5%, among them hypodontia was 3.1%. Prevalence of third molar agenesis varies in different geographic region. Among the other dental anomalies hypodontia was more prevalent. PMID:27580050

  12. Space changes after premature loss of the mandibular primary first molar: a longitudinal study.

    PubMed

    Lin, Y T; Chang, L C

    1998-01-01

    The purpose of this study was to evaluate the space changes after premature loss of the primary mandibular first molar. Twenty-one children (12 boys and 9 girls), with premature loss of the primary mandibular first molar, were selected from the children's dental clinic for this study. The age ranged from 5.1 to 7.2 years with an average of 6 years and 11 months. Mandibular study casts were made from alginate impression for each initial examination and a follow-up examination eight months later. Four measurements including D+E (first and second primary molars) space, arch width, arch length and arch perimeter were tested for comparisons between the initial examination and the follow-up examination eight months later. The D+E space of intact primary molars served as a control. The results showed that the D+E space on the extraction side after the follow-up examination eight months later was significantly shorter than the control side (p = 0.025) and less than the initial D+E space (p < 0.001). However, there were no significant differences on arch width, arch length, and arch perimeter between the initial examination and the follow-up examination eight months later (p > 0.05). It is concluded that the space change after the eruption of the first permanent molar in the mandible is mostly distal movement of the primary cuspid during the early stage of premature loss of the primary first molar.

  13. Occlusal migration of the maxillary first primary molars subsequent to the loss of antagonists.

    PubMed

    Yonezu, T; Machida, Y

    1997-08-01

    The purpose of this study was to observe the vertical changes in unopposed maxillary first primary molars longitudinally. The subjects of this study were 17 children whose lower first primary molars had to be extracted. Space closure were prevented by crown-loop space maintainers for all these children. Plaster casts were made every 4 months for 16 to 24 months after the extraction. These series of casts were standardized, and vertical changes of the maxillary first primary molars against the occlusal plane were measured using a micro-reader. The mean changes indicated that maxillary first primary molars without intercuspidation tend to drift toward the extraction space. On the control side with antagonists, the maxillary first molars seemed to move reversed to apical throughout the observation period. Accordingly, the results of this study showed new trends after the premature loss of primary molars. The vertical changes toward extraction space varied from -0.40 mm to 1.43 mm at the 16 months after extraction. Mean changes were small, but there were some individual differences in reaction, giving negative values. However, we should always be concerned about loss of arch length and also occlusal drift of unopposed teeth, because the vertical changes were greater than 1 mm at 16 months after extraction in some cases.

  14. Dental age estimation from the developmental stage of the third molars in western Chinese population.

    PubMed

    Li, Guo; Ren, Jiayin; Zhao, Shuping; Liu, Yuanyuan; Li, Na; Wu, Wanhong; Yuan, Shanshan; Wang, Hu

    2012-06-10

    The purpose of this study is to provide reference data about estimating dental age from third molars of the western Chinese population for comparing with other populations and being applied to the age estimation of western Chinese juveniles and adolescents. A total of 2078 digital panoramic radiographs of 989 male and 1089 female Chinese subjects aged between 5 and 23 years were examined. The mineralization status of the third molars was assessed using the formation stages described by Demirjian et al. with two modifications. The results showed that the development of third molars in the western Chinese population was likely to begin at age 5 in both males and females. The third molars 28 and 48 showed significantly higher frequency in females than in males. The third molars 18 in the stage 1, 38 in the stages 1, A and G, and 48 in the stage H showed significantly older average age in females than in males. The Demirjian's stages C and D could be used as a reference stage to determine dichotomously whether a western Chinese is more likely to be under or above age 14 or 16, respectively. This study provided reference data for the age estimation of western Chinese juveniles and adolescents by the mineralization stages of the third molar. Apart from forensic age determination in living subjects, the presented reference data can also be used for age estimations of unidentified corpses and skeletons.

  15. 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

  16. Prevalence of Third Molar Agenesis: Associated Dental Anomalies in Non-Syndromic 5923 Patients.

    PubMed

    Sujon, Mamun Khan; Alam, Mohammad Khursheed; Rahman, Shaifulizan Abdul

    2016-01-01

    The aim of this study was to investigate the prevalence of third molar agenesis and other associated dental anomalies in Bangladeshi population and to investigate the relationship of other dental anomalies with the third molar presence/agenesis. A retrospective study was performed using panoramic radiographs of 5923 patients, who ranged in age from 10 to 50 years. All radiographs were analyzed by Planmeca Romexis® 3.0 software (Planmeca Oy, Helsinki, Finland). Pearson chi-square and one way ANOVA (Post Hoc) test were conducted. The prevalence of third molar agenesis was 38.4%. The frequency of third molar agenesis was significantly higher in females than males (p <0.025). Third molar agenesis was significantly more prevalent in maxilla as compared to mandible (p <0.007). The prevalence of other dental anomalies was 6.5%, among them hypodontia was 3.1%. Prevalence of third molar agenesis varies in different geographic region. Among the other dental anomalies hypodontia was more prevalent. PMID:27580050

  17. 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.

  18. 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.

  19. Comparison of K-loop Molar Distalization with that of Pendulum Appliance - A Prospective Comparative Study

    PubMed Central

    Shashidhar, Nagam Reddy; Reddy, S.Rama Koteswara

    2016-01-01

    Introduction Molar distalization is the non extraction method of managing Class II malocclusions. Aim The purpose of this study was to evaluate the skeletal and dentoalveolar effects of maxillary molar distalization with K-loop appliance, and to compare these effects with that of pendulum group. Materials and Methods Class I and dental Class II malocclusions were divided into two groups of 15 each: In Group 1 (nine females and six males; mean age, 16.0±2.6 years) patients were treated with K-Loop molar distalization supported palatally by Nance button, while in Group 2 (seven females and eight males; mean age, 15.4±4.7 years), the patients were treated with conventional pendulum appliance. Standardized lateral cephalograms were taken at the beginning of treatment (T0) and at the end of molar distalization (T1) and the changes were statistically analyzed with paired t-test. Results The results showed no statistically significant difference in the amount of molar distalization in either of the appliance groups: the mean amount of molar distal movement of 5.1±0.8 mm and 4.93±1.68 mm was observed in the Group 1 and 2 respectively. The incisors moved mesially by 1.3±0.63 mm in Group 1 and 1.57±0.58 mm in Group 2. Conclusion K-Loop molar distalizing appliance has similar skeletal and dentoalveolar effects as that of pendulum appliance, with the advantages of simple yet efficient to control the moment-force ratio to produce all types of tooth movements and also requires minimal patient co-operation. PMID:27504403

  20. Morphologic criteria for root canal treatment of primary molars undergoing resorption.

    PubMed

    Rimondini, L; Baroni, C

    1995-06-01

    The endodontic anatomy of primary molars is difficult to predict because of the balance of resorption and hard tissue deposition. In particular, the resorption causes perforating lacunae across the wall of the root, even at the furcation level, and modifies shape, dimension and position of endodontic apex. The phenomenon can be so deep as to compromise endodontic therapy. The first aim of the study was to verify if reliable criteria can be found for treatability in primary molars undergoing resorption, i.e. if it is possible to predict if perforating lacunae are present or not. The second aim of the study was to verify if other informations needed for endodontic treatment, as shape, dimension and location of the apex, and curvature of the root canal can be predicted. For the study, 80 extracted primary molars, 75 of which pulpally involved by caries, were selected. The treatability was evaluated in term of root length, root shape, dimension and shape of endodontic apex, age of the patient and X-ray index of resorption. The association between variables was performed by multiple correspondence analysis. The results suggested that root length was the most reliable criterion of the integrity of the root. The borderline of treatability was at the length of 4 mm. The position of endodontic apex related to anatomical apex, and the lingual related to the buccal root length were analyzed by linear regression analysis. The canal length was often similar to the root length (i.e. the endo and anatomical apices were very close) in lower and upper molars. However, in lower molars, if two or more canals were present in the same root, a discrepancy was observed between buccal and lingual root length. This finding was constant in first lower molars. In addition regression analysis provided a linear function between the lengths of the buccal and lingual side of the same root in lower molars. Its coefficient b was 0.73. PMID:7641630