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1

Partial molar volume of water in phonolitic glasses and liquids  

Microsoft Academic Search

The volumes and expansivities of four hydrous phonolite glasses and liquids have been measured by dilatometry from 300 K up to the glass transition and over a 50 K interval just above the glass transition. The partial molar volume of water is independent of the water content for the glass and liquid phases, with values of about 11.0ǂ.5 and 17.1ǂ.9

Ali M. Bouhifd; Alan Whittington; Pascal Richet

2001-01-01

2

Densities, excess molar volumes, and partial molar volumes for binary mixtures of water with monoethanolamine, diethanolamine, and triethanolamine from 25 to 80°C  

Microsoft Academic Search

We have measured densities of binary mixtures of water with monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA) over the full range of compositions and over the temperature range from 25 to 80°C. Results of these measurements have been used in calculating excess molar volumes and partial molar volumes. Knowledge of the volumetric properties of these mixtures is useful in connection

Yadollah Maham; Tjoon T. Teng; Loren G. Hepler; Alan E. Mather

1994-01-01

3

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

NASA Astrophysics Data System (ADS)

Densities (?) 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 (? v ) of isoniazid in different media. The ? v data were fitted to Massons relation and partial molar volumes (?{/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.

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

2015-02-01

4

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

5

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

PubMed

The impact of attractive interactions on the partial molar volumes of methane-like solutes in water is characterized using molecular simulations. Attractions account for a significant 20% volume drop between a repulsive Weeks-Chandler-Andersen and full Lennard-Jones description of methane interactions. The response of the volume to interaction perturbations is characterized by linear fits to our simulations and a rigorous statistical thermodynamic expression for the derivative of the volume to increasing attractions. While a weak non-linear response is observed, an average effective slope accurately captures the volume decrease. This response, however, is anticipated to become more non-linear with increasing solute size. PMID:24410241

Williams, Steven M; Ashbaugh, Henry S

2014-01-01

6

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

SciTech Connect

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

Williams, Steven M.; Ashbaugh, Henry S., E-mail: hanka@tulane.edu [Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118 (United States)

2014-01-07

7

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

PubMed

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

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

2015-02-14

8

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

PubMed

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

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

2014-10-01

9

The Partial Molar Volume and Heat Capacity of the Glycyl Group in Aqueous Solution at 25^C  

Microsoft Academic Search

The partial molar volumes, V2\\u000a ^, and the partial molar heat capacities, Cp,2\\u000a ^, at infinite dilution have been determined for three new peptides of sequence seryl(glycyl)xglycine, where x=0 to 2, in aqueous solution at 25^C. Values for V2\\u000a ^ at 25°C have also been determined for two neutral peptide derivatives N-acetylglycylglycinamide and N-acetylglycylglycylglycinamide. These V2\\u000a °; and Cp,2\\u000a °;

Nessha M. Wise; Gavin R. Hedwig

2006-01-01

10

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

E-print Network

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 ap- proximation for the free-energy functional, the so-called homogeneous reference uid approximation, we show that the hydration free-energies computed for a dataset of 500 organic compounds are of similar quality as those obtained from molecular dynamics free-energy perturbation simulations, with a computer cost reduced by two to three orders of magnitude. This requires to introduce the proper partial volume correction to transform the results from the grand canoni- cal 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 justifcation to empirical partial molar volume corrections that have been proposed recently.

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

2014-06-11

11

Determination of the partial molar volume of SiO{sub 2} in silicate liquids at elevated pressures and temperatures: A new experimental approach  

SciTech Connect

This study presents a new approach for determining the partial molar volume and its pressure derivative for a silicate liquid component through an experimental determination of the isothermal pressure dependence of the solubility in the liquid of a crystalline phase having the composition of the component. Because this approach allows the determination of partial molar volumes of liquid components at elevated pressure, it has the potential to detect pressure-induced structural changes associated with particular components in silicate liquid through their influence on partial molar volumes. To illustrate the approach, an experimental determination of the solubility of quartz in a rhyolitic liquid was used to determine the partial molar volume of SiO{sub 2} at pressures up to 35 kbar and a temperature of 1,350 C. The 1 bar partial molar volume for SiO{sub 2} determined in this way, 2.635 {+-} 0.009 J/bar, is slightly smaller than the 2.690 {+-} 0.006 J/bar determined by Lange and Carmichael (1987) (all uncertainties are 1{sigma}). The isothermal pressure dependence of the partial molar volume of SiO{sub 2} at 10 to 35 kbar is approximately one-half of the value determined by Kress and Carmichael (1991) at 1 bar. The high pressure determination can be reconciled with the existing 1 bar volume and compressibility data if the isothermal pressure dependence of the partial molar volume of SiO{sub 2} in silicate liquids decreases rapidly between 1 bar and 10 kbar, then remains approximately constant to at least 35 kbar.

Gaetani, G.A.; Asimow, P.D.; Stolper, E.M. [California Inst. of Tech., Pasadena, CA (United States). Div. of Geological and Planetary Sciences] [California Inst. of Tech., Pasadena, CA (United States). Div. of Geological and Planetary Sciences

1998-07-01

12

Partial Molar Volumes of Some of ?-Amino Acids in Binary Aqueous Solutions of MgSO 4 ·7H 2 O at 298.15 K  

Microsoft Academic Search

The apparent molar volume, V\\u000a o\\u000a ?, 2, of glycine, alanine, ?-amino-n-butyric acid, valine and leucine have been determined in aqueous solutions of 0.25, 0.5 and 1.0 mol?dm?3 magnesium sulfate, and the partial specific volume from density measurements at 298.15 K. These data have been used to calculate the infinite dilution apparent molar volume, V\\u000a o\\u000a 2,m\\u000a , group contribution

Bairagi C. Mallick; Nand Kishore

2006-01-01

13

Standard partial molar volumes of some aqueous alkanolamines and alkoxyamines at temperatures up to 325 degrees C: functional group additivity in polar organic solutes under hydrothermal conditions.  

PubMed

Apparent molar volumes of dilute aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), N,N-dimethylethanolamine (DMEA), ethylethanolamine (EAE), 2-diethylethanolamine (2-DEEA), and 3-methoxypropylamine (3-MPA) and their salts were measured at temperatures from 150 to 325 degrees C and pressures as high as 15 MPa. The results were corrected for the ionization and used to obtain the standard partial molar volumes, Vo2. A three-parameter equation of state was used to describe the temperature and pressure dependence of the standard partial molar volumes. The fitting parameters were successfully divided into functional group contributions at all temperatures to obtain the standard partial molar volume contributions. Including literature results for alcohols, carboxylic acids, and hydroxycarboxylic acids yielded the standard partial molar volume contributions of the functional groups >CH-, >CH2, -CH3, -OH, -COOH, -O-, -->N, >NH, -NH2, -COO-Na+, -NH3+Cl-, >NH2+Cl-, and -->NH+Cl- over the range (150 degrees C partial molar volume of aqueous organic solutes composed of these groups at temperatures up to approximately 310 degrees C and pressures of 10-20 MPa to within a precision of +/-5 cm3 x mol(-1). The model could not be extended to higher temperatures because of uncertainties caused by thermal decomposition. At temperatures above approximately 250 degrees C, the order of the group contributions to Vo2 changes from that observed at 25 degrees C, to become increasingly consistent with the polarity of each functional group. The effect of the dipole moment of each molecule on the contribution to Vo2 from long-range solvent polarization was calculated from the multipole expansion of the Born equation using dipole moments estimated from restricted Hartree-Fock calculations with Gaussian 03 (Gaussian, Inc., Wallingford, CT) and the Onsager reaction-field approximation for solvent effects. Below 325 degrees C, the dipole contribution was found to be less than 2 cm3 x mol(-1) for all the solute molecules studied. At higher temperatures and pressures near steam saturation, the effect is much larger and may explain anomalies in functional group additivity observed in small, very polar solutes. PMID:18412415

Bulemela, E; Tremaine, Peter R

2008-05-01

14

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

...false Molar Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents 1 ...Part 60—Molar Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents Constituent...F and 1 atmosphere. b MHC = molar heat content (higher heating value...

2014-07-01

15

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

...false Molar Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents 1 ...Part 60—Molar Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents Constituent...F and 1 atmosphere. b MHC = molar heat content (higher heating value...

2013-07-01

16

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

17

Molarity  

NSDL National Science Digital Library

What determines the concentration of a solution? Learn about the relationships between moles, liters, and molarity by adjusting the amount of solute and solution volume. Change solutes to compare different chemical compounds in water.

Simulations, Phet I.; Chamberlain, Julia; Malley, Chris; Lancaster, Kelly; Parson, Robert; Perkins, Kathy

2012-02-20

18

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

NASA Astrophysics Data System (ADS)

Density and sound speed measurements were obtained over a wide range of temperature for three model basalt liquids in the An-Di-Hd (CaAl2Si2O8-CaMgSi2O6-CaFeSi2O6) system. High-temperature (1585-1838 K) double-bob density measurements were combined with low-temperature (943-930 K) measurements at the limiting fictive temperature for each sample to provide liquid volume data over a temperature interval of ?900 K. In addition, relaxed sound speeds were obtained with a frequency sweep acoustic interferometer from 1665-1876 K. An ideal mixing model for molar volume, thermal expansivity, and isothermal compressibility recovers the new data from this study and leads to the following fitted values (±2?) at 1723 K for VbarFeO (12.86±0.32 cm/mol), ?VbarFeO/?T((3.69±1.16)×10-3 cm/mol-K) and ?barT,FeO((4.72±0.46)×10-2 GPa). These volumetric properties for the FeO component are estimated to reflect Fe2+ in an average coordination of 5.7 (±0.2), based on the relationship between VbarFeO and Fe2+ coordination derived by a comparison to mineral molar volumes (Guo et al., 2013). Application of these volumetric data to a calculation of the pressure dependence of the Fe-Mg exchange reaction between orthopyroxene and basaltic liquid results in a small decrease in Fe-MgKD with pressure. In contrast, partial melting experiments of peridotite show a small increase in Fe-MgKD(opx-liq) with pressure (e.g., Walter, 1998). This difference in the pressure dependence is proposed to reflect the role of alkalis in reducing the average coordination number of Fe2+ toward five compared to the alkali-free model basalt compositions in this study, thus changing the volume and compressibility of the FeO liquid component. The results from this study may be most appropriately applied to lunar basalts, which are impoverished in alkalis.

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

2014-02-01

19

Fragility and molar volumes of non-stoichiometric chalcogenides  

E-print Network

accurately using the age old Archimedes' principle that was enunciated about 250 BC in Syracuse, Italyreprint #12;Fragility and molar volumes of non-stoichiometric chalcogenides: The crucial role chalcogenides, fragility, glass, modulated differential scanning calorimetry, rigidity, stress * Corresponding

Boolchand, Punit

20

Nuclear relaxation in bcc 3 He for large molar volumes  

Microsoft Academic Search

We report the results of measurements of longitudinal and transverse nuclear relaxation timesT1 andT2 in bcc3He at 300 mK and at a Larmor frequency of 3 MHz for molar volumes 22.6?V?24.9 cm3. It is found, even in this extended range of molar volumes, that the relaxation times increase withV as\\u000a

M. Devoret; A. S. Greenberg; D. Estève; N. S. Sullivan; M. Chapellier

1982-01-01

21

Correlations between elastic moduli and molar volume in metallic glasses  

NASA Astrophysics Data System (ADS)

We report clear correlations between bulk modulus (K) and average molar volume Vm, and between Poisson's ratio ? and Vm for various bulk metallic glasses. The origin for the correlations between elastic moduli and Vm are discussed. The established correlation, associated with Poisson's ratio ?, and since the ? correlates with plasticity of metallic glasses, indicates that the average molar volume is important factor to be considered for plastic metallic glasses searching. The found correlations also suggest a close relation between the mechanical properties and the short-range atomic bonding, and assist in understanding deformation behavior in metallic glasses.

Wang, J. Q.; Wang, W. H.; Yu, H. B.; Bai, H. Y.

2009-03-01

22

Correlations between elastic moduli and molar volume in metallic glasses  

SciTech Connect

We report clear correlations between bulk modulus (K) and average molar volume V{sub m}, and between Poisson's ratio {nu} and V{sub m} for various bulk metallic glasses. The origin for the correlations between elastic moduli and V{sub m} are discussed. The established correlation, associated with Poisson's ratio {nu}, and since the {nu} correlates with plasticity of metallic glasses, indicates that the average molar volume is important factor to be considered for plastic metallic glasses searching. The found correlations also suggest a close relation between the mechanical properties and the short-range atomic bonding, and assist in understanding deformation behavior in metallic glasses.

Wang, J. Q.; Wang, W. H.; Yu, H. B.; Bai, H. Y. [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

2009-03-23

23

Excess molar volumes and excess molar enthalpies of quinoline + aromatic hydrocarbons at 303. 15 K  

SciTech Connect

Excess molar volumes V[sub m][sup E] and excess molar enthalpies H[sub m][sup E][sub m] for quinoline + benzene, toluene, o-xylene, or p-xylene for the whole range of compositions have been measured at 303.15 K. The values of H[sub m][sup E] and V[sub m][sup E] for these mixtures suggest that quinoline is partly self-associated and there is strong interaction (weak hydrogen bonding) between quinoline and aromatic hydrocarbons. The values of V[sub m][sup E] and H[sub m][sup E] have also been computed from the Flory and Abe theory and Sanchez and Lacombe theory as well as from the Graph theory. All the theories correctly predict the sign or magnitude of H[sub m][sup E]. Only the Graph theory is able to predict correctly the sign or magnitude of V[sub m][sup E]; the other theories give a poor estimate of V[sub m][sup E].

Kalra, K.C.; Singh, K.C.; Spah, D.C.; Batra, R.; Maken, S. (Maharshi Dayanand Univ., Rohtak (India). Dept. of Chemistry)

1993-01-01

24

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

PubMed

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

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

2014-01-01

25

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

SciTech Connect

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.

Reynolds, Jacob G. [Washington River Protection Solutions, Richland, WA (United States)

2013-01-11

26

Molar volume dependence of the thermal conductivity in mixed cryocrystals  

NASA Astrophysics Data System (ADS)

The dependence of the thermal conductivity ? of solid solutions of cryocrystals on the molar volume is investigated theoretically in the Callaway approach under the assumption that the heat is transferred by mobile low-frequency phonons and, above the phonon mobility edge, by "localized" modes which migrate randomly from site to site. The phonon mobility edge ?0 is found from the condition that the phonon mean free path, which is governed by umklapp processes and scattering on point defects, cannot become smaller than one-half the phonon wavelength. The Bridgman coefficient g=-(? ln ?/? ln V)T is the weighted mean over these modes, which have strongly different volume dependences. For the example of the solid solution Kr1-c(CH4)c, where c is the mole fraction of the components, it is shown that with increasing methane concentration in krypton the Bridgman coefficient decreases, in good agreement with experiment, from g?9, characteristic for the pure crystals, to g?4.

Konstantinov, V. A.; Orel, E. S.; Revyakin, V. P.

2002-02-01

27

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

SciTech Connect

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)

Reynolds, Jacob G. [Washington River Protection Solutions, LLC, P.O. Box 850, Richland, WA 99352 (United States)] [Washington River Protection Solutions, LLC, P.O. Box 850, Richland, WA 99352 (United States)

2013-07-01

28

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

SciTech Connect

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.

Reynolds, Jacob G. [Washington River Protection Solutions, LLC, Richland, WA (United States)

2013-01-11

29

Evaluation of Molar Volume Effect for Calculation of Diffusion in Binary Systems  

NASA Astrophysics Data System (ADS)

This article relates the theoretical evaluation of the effect of a molar volume change in the diffusion profile of a binary system. This study is based on the regression fit of a diffusion profile using a selected function in an inverse form. For the calculation of concentration-dependent diffusivity according to the Sauer and Freise (and Wagner) treatment of the Boltzmann-Matano relation, this inverse regression function is further modified by the inclusion of molar volume, which is dependent on the molar composition of a diffusing two-component mixture. Following the conversion of the initial relation to the form that enables the direct integration of the used inverse function, which fits the diffusion profile, the formulas for the analytical calculation of diffusivity are obtained. These formulas are derived both for the linear change in molar volume in the diffusion profile corresponding to Vegard's rule and for the case of the positive or negative deviations from the linearity representing the swell or shrink course V m. The analysis results show that the drop and swell shapes of the course of molar volume in a diffusion profile of the binary system increase the resulting diffusivity. Conversely, the increase of V m and its shrink course are factors that lower diffusivity. The regression function that was used in its inverse form was suitable for fitting the diffusion profile of any asymmetrical shape. The derived relations are therefore practically applicable for the direct analytical calculation of concentration-dependent diffusivity in binary systems.

Vach, Marek; Svojtka, Martin

2012-12-01

30

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

NASA Astrophysics Data System (ADS)

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 more buoyant at depth than previously thought, facilitating their extraction and rapid ascent.

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

2010-12-01

31

Partial molar adiabatic compressibilities and viscosities of some amino acids in aqueous glycerol solutions at 298.15 K  

Microsoft Academic Search

, ? and viscosity B-coefficients, and their corresponding transfer functions. The positive partial molar adiabatic compressibilities of transfer at infinite dilution, ?tr o s 2 , ? , have been observed for the studied amino acids (except at lower concentration up to ? 0.6 mB in some cases), and their magnitude increases with increase in concentration of glycerol. B-coefficient of

Gagandeep Singh; T S Banipal

32

Entropy Estimates for Some Silicates at 298{degrees}K from Molar Volumes.  

PubMed

Third law entropies for silicates of Be, Mg, Ca, Zn, Na, and K containing the same anion group, for example, SiO(4) or SiO(3) or AlSi(3)O(8), are found to be linearly related to their molar volumes. The relationship between the molar volume and the entropy of silicates of Fe and Mn, atoms with unfilled d electron subshells, is different from that of other silicates. The linear correlations yield a useful method of estimating the entropies of ortho-, meta-, and framework silicates (feldspars and feld-spathoids). The estimated entropies of pyrope and almandine at 298 degrees K are 47.47 and 68.13 gibbs per mole, respectively. PMID:17837020

Saxena, S K

1976-09-24

33

Partial volume correction in quantitative amyloid imaging.  

PubMed

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

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

2015-02-15

34

Solute partial molal volumes in supercritical fluids  

SciTech Connect

A novel technique is described for the measurement of the partial molal volume at infinite dilution of solutes in supercritical fluids. Results are reported for five systems from 2/sup 0/C above the solvent critical temperature up to 15/sup 0/C above, at pressures from just above the critical pressure to 350 bars. The solute partial molal volumes are small and positive at high pressures, but very large and negative in the highly compressible near-critical region. The results are interpreted in terms of solvent structure and intermolecular forces.

Eckert, C.A.; Ziger, D.H.; Johnston, K.P.; Kim, S.

1986-06-05

35

Molecular dynamics simulation of the molar volumes and solubility parameters of straight alkanes  

NASA Astrophysics Data System (ADS)

The straight chain n-alkanes used as core materials to fabricate nanoencapsulated and microencapsulated phase change of materials (PCM) have received much attention in recent years. The dissipative particle dynamics (DPD) simulation method has been emerged to investigate the encapsulated PCM from the perspective of mesoscopic. To obtain the Flory-Huggins and repulsion parameters, which is essential for the DPD study, the molar volume and solubility parameter of straight alkanes are investigated by using molecular dynamics (MD) simulation. The results showed that a linear relationship of molar volume (V) with carbon atom number (n) and simulation temperature (T) can be obtained as: V = -31.73 + 0.26T + 14.82n. A nonlinear relationship of solubility parameter (?) with carbon atom number and simulation temperature can be described as: ? = 18.45-3.66 ×10-2n + 1.07T - 1.20 ×10-5n2 - 9.60 ×10-2T2 - 2.49 ×10-3nT. The equations can be used as a reference for the further DPD simulation in n-alkanes based PCM system.

Liu, Xinjian; Rao, Zhonghao; Huo, Yutao

2014-12-01

36

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

PubMed Central

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 ?m) 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

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

2014-01-01

37

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

SciTech Connect

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

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

1986-03-01

38

Excess molar volumes and excess molar enthalpies of binary and ternary mixtures of 1-butanol, a tertiary amine (tri- n-butylamine or tri- n-octylamine) and n-hexane: Experimental results and ERAS-model calculations  

Microsoft Academic Search

Experimental data at T=298.15K and ambient pressure of excess molar volumes VmE and excess molar enthalpies HmE are reported for two ternary and the corresponding binary mixtures of {1-butanol, tri-n-butylamine (TBA), or tri-n-octylamine (TOA), and n-hexane}. A vibrating-tube densitometer was used to determine VmE. HmE was measured using a quasi-isothermal flow calorimeter. The experimental results are used to test the

Matthias Kwaterski; Elena N. Rezanova; Rüdiger N. Lichtenthaler

2006-01-01

39

Molecular Polarizability of Organic Compounds and Their Complexes: XLVIII. Molar Volumes of Benzene Derivatives in Solutions at Infinite Dilution, Their Additivity, and Correlation with the Dipole Moments and Kerr Constants  

Microsoft Academic Search

Extrapolation formulas were derived for determination of the molar volume of a solute at infinite dilution. This quantity\\u000a is stable to solvent replacement and additive with respect to increments of substituents in polysubstituted benzenes. The\\u000a molar polarization and molar Kerr constant of a solute can be expressed through the molar volumes of the solute at infinite\\u000a dilution and of the

S. B. Bulgarevich; T. V. Burdastykh; L. G. Tishchenko; I. V. Kosheleva

2005-01-01

40

Fragility and molar volumes of non-stoichiometric chalcogenides: The crucial role of melt/glass homogenization  

NASA Astrophysics Data System (ADS)

Melt-fragility index (m) and glass molar volumes (Vm) of binary Ge-Se melts/glasses are found to change reproducibly as they are homogenized. Variance of Vm decreases as glasses homogenize, and the mean value of Vm increases to saturate at values characteristic of homogeneous glasses. Variance in fragility index of melts also decreases as they are homogenized, and the mean value of m decreases to acquire values characteristic of homogeneous melts. Broad consequences of these observations on physical behavior of chalcogenides melts/glasses are commented upon. The intrinsically slow kinetics of melt homogenization derives from high viscosity of select super-strong melt compositions in the Intermediate Phase that serve to bottleneck atomic diffusion at high temperatures.

Bhageria, R.; Gunasekera, K.; Boolchand, P.; Micoulaut, M.

2014-07-01

41

Partial molar volume fraction of solvent in binary (CO 2–solvent) solution for solid solubility predictions  

Microsoft Academic Search

Prediction of solid solute solubility in an organic solvent with dissolution of dense CO2 as antisolvent is important for the design of antisolvent crystallization processes. A new model is proposed in this work to predict the mole fraction of a pure solid solute in a ternary (CO2–solvent–solid) system at solid–liquid equilibrium. This is based on the hypothesis that CO2 molecules

Mamata Mukhopadhyay; Sameer V. Dalvi

2004-01-01

42

Partial volume effects in dynamic contrast magnetic resonance renal studies.  

PubMed

This is the first study of partial volume effect in quantifying renal function on dynamic contrast enhanced magnetic resonance imaging. Dynamic image data were acquired for a cohort of 10 healthy volunteers. Following respiratory motion correction, each voxel location was assigned a mixing vector representing the 'overspilling' contributions of each tissue due to the convolution action of the imaging system's point spread function. This was used to recover the true intensities associated with each constituent tissue. Thus, non-renal contributions from liver, spleen and other surrounding tissues could be eliminated from the observed time-intensity curves derived from a typical renal cortical region of interest. This analysis produced a change in the early slope of the renal curve, which subsequently resulted in an enhanced glomerular filtration rate estimate. This effect was consistently observed in a Rutland-Patlak analysis of the time-intensity data: the volunteer cohort produced a partial volume effect corrected mean enhancement of 36% in relative glomerular filtration rate with a mean improvement of 7% in r(2) fitting of the Rutland-Patlak model compared to the same analysis undertaken without partial volume effect correction. This analysis strongly supports the notion that dynamic contrast enhanced magnetic resonance imaging of kidneys is substantially affected by the partial volume effect, and that this is a significant obfuscating factor in subsequent glomerular filtration rate estimation. PMID:19501996

Gutierrez, D Rodriguez; Wells, K; Diaz Montesdeoca, O; Moran Santana, A; Mendichovszky, I A; Gordon, I

2010-08-01

43

Partial volume correction using an energy multiresolution analysis  

Microsoft Academic Search

Position Emission Tomography (PET) allows the in-vivo monitoring of functional processes in the body. However its limited spatial resolution induces Partial Volume Effect (PVE), which leads to a loss of signal in tissues of size similar to the Point Spread Function (PSF) of the imaging device and induces activity spillover between adjacent structures with different amounts of activity. The aim

Francisca P. Figueiras; Xavier Jimenez; Deborah Pareto; Juan D. Gispert

2009-01-01

44

Phase boundaries and molar volumes of high-temperature and high-pressure phase V of LiBH4  

NASA Astrophysics Data System (ADS)

Raman measurements up to 14 GPa and 570 K and powder x-ray diffraction measurement from 4 to 28 GPa at 510 K were used to investigate the high-temperature and high-pressure phases of LiBH4. The B-H stretching Raman bands in high-temperature and high-pressure phase V were observed as one broad peak, which would arise from the disordered structure. The rotation of BH4 - ions has also been observed by a quantum MD calculation. The results are consistent with the reported structure of phase V that is known to be an orientationally disordered structure. The Raman measurements indicated that the phase boundary between phases I and V and that between phases III and V have a negative slope against pressure. The negative slope could be explained by the Clausius-Clapeyron equation, assuming that the entropy of phase V is larger than that of phase I or III for the disordered structure of phase V. The molar volume of phase V, despite being a high-temperature phase, is smaller than that of phase III at the same pressure from powder x-ray diffraction measurement; therefore, the thermal expansion would be small compared to the volume change at the phase transition from phase III to V.

Yamawaki, Hiroshi; Fujihisa, Hiroshi; Gotoh, Yoshito; Nakano, Satoshi

2015-01-01

45

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

NASA Astrophysics Data System (ADS)

Extensive molecular dynamics studies of 13 different silica polymorphs are reported in the isothermal-isobaric ensemble with the Parrinello-Rahman variable shape simulation cell. The van Beest-Kramer-van Santen (BKS) potential is shown to predict lattice parameters for most phases within 2%-3% accuracy, as well as the relative stabilities of different polymorphs in agreement with experiment. Enthalpies of high-density polymorphs - CaCl2-type, ?-PbO2-type, and pyrite-type - for which no experimental data are available as yet, are predicted here. Further, the calculated enthalpies exhibit two distinct regimes as a function of molar 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.

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

2014-06-01

46

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

PubMed

Extensive molecular dynamics studies of 13 different silica polymorphs are reported in the isothermal-isobaric ensemble with the Parrinello-Rahman variable shape simulation cell. The van Beest-Kramer-van Santen (BKS) potential is shown to predict lattice parameters for most phases within 2%-3% accuracy, as well as the relative stabilities of different polymorphs in agreement with experiment. Enthalpies of high-density polymorphs - CaCl2-type, ?-PbO2-type, and pyrite-type - for which no experimental data are available as yet, are predicted here. Further, the calculated enthalpies exhibit two distinct regimes as a function of molar 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. PMID:24985659

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

2014-06-28

47

Apparent molar volume, viscosity B-coefficient, and adiabatic compressibility of tetrabutylammonium bromide in aqueous ascorbic acid solutions at T = 298.15, 308.15, and 318.15 K  

NASA Astrophysics Data System (ADS)

Apparent molar volumes ?? and viscosity B-coefficients for tetrabutyl ammonium bromide (TBAB) in (0.00, 0.05, 0.10, and 0.15) mol dm-3 aqueous ascorbic acid solutions have been determined from solution density and viscosity measurements at temperatures over the range 298.15 to 318.15 K as function of concentration of ascorbic acid solutions. In the investigated temperature range, the relation: ?{?/0} = a 0 + a 1 T + a 2 T 2, have been used to describe the partial molar volume ?{?/0}. These results, in conjunction with the results obtained in pure water, have been used to calculate the standard volumes of transfer ??{/? 0} and viscosity B-coefficients of transfer for TBAB from water to aqueous ascorbic acid solutions for rationalizing various interactions in the ternary solutions. The structure making or breaking ability of TBAB has been discussed in terms of the sign of (?2?{?/0}/? T 2) P . An increase in the transfer volume of TBAB with increasing ascorbic acid concentration has been explained by Friedman-Krishnan co-sphere model. The activation parameters of viscous flow for the ternary solutions studied have also been calculated and explained by the application of transition state theory.

Roy, M. N.; Das, R. K.; Bhattacharjee, A.

2010-12-01

48

Molar Uprighting  

MedlinePLUS

... molar uprighting are the same as with any orthodontic procedure. There may be some discomfort. Also, the ... These can happen more often in people with orthodontic appliances, especially if they don't brush and ...

49

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

50

Anisotropic Partial Volume CSF Modeling for EEG Source Localization  

PubMed Central

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

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

2012-01-01

51

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

52

Temperature Dependence of Densities and Excess Molar Volumes of the Ternary Mixture (1-Butanol + Chloroform + Benzene) and its Binary Constituents (1-Butanol + Chloroform and 1-Butanol + Benzene)  

NASA Astrophysics Data System (ADS)

Densities ? of the 1-butanol + chloroform + benzene ternary mixture and the 1-butanol + chloroform and 1-butanol + benzene binaries have been measured at six temperatures (288.15, 293.15, 298.15, 303.15, 308.15, and 313.15) K and atmospheric pressure, using an oscillating U-tube densimeter. From these densities, excess molar volumes ( V E) were calculated and fitted to the Redlich Kister equation for all binary mixtures and to the Nagata and Tamura equation for the ternary system. The Radojkovi? et al. equation has been used to predict excess molar volumes of the ternary mixtures. Also, V E data of the binary systems were correlated by the van der Waals (vdW1) and Twu Coon Bluck Tilton (TCBT) mixing rules coupled with the Peng Robinson Stryjek Vera (PRSV) equation of state. The prediction and correlation of V E data for the ternary system were performed by the same models.

Smiljani?, Jelena D.; Kijev?anin, Mirjana Lj.; Djordjevi?, Bojan D.; Grozdani?, Dušan K.; Šerbanovi?, Slobodan P.

2008-04-01

53

Artificially low cortical bone mineral density in Turner syndrome is due to the partial volume effect.  

PubMed

We aimed to show that the decrease in the cortical bone mineral density (BMD) in the radius in Turner syndrome (TS) is artificially caused by the partial volume effect. We confirmed that the partial volume effect-corrected cortical BMD is not decreased in TS compared to in the healthy controls. Other factors are responsible for the increased fracture rate in TS. PMID:25288443

Soucek, O; Schönau, E; Lebl, J; Sumnik, Z

2014-10-01

54

The variation of viscosity, refractive indices, compressibility, intermolecular free length, and excess molar volume of the acetophenone—ethyl acetate solutions at 303.15-323.15 K  

NASA Astrophysics Data System (ADS)

Densities, viscosities, refractive indices and ultrasonic velocities of the binary mixtures of acetophenone with ethyl acetate were measured over the entire mole fractions at 303.15, 313.15, and 323.15 K. From the experimental results, excess molar volumes V E, viscosity deviation ??, refractive index deviation ? n D , deviations in isentropic compressibility ?? s and excess intermolecular free length ? L f are calculated. The viscosity values were fitted to the models of Krishnan-Laddha and McAllister. The thermophysical properties under study were fit to the Jouyban-Acree model. The excess values were correlated using Redlich-Kister polynomial equation to obtain their coefficients and standard deviations. The data obtained fitted with the values correlated by the corresponding models very well. The results are interpreted in terms of molecular interactions occurring in the solution.

Saravanakumar, K.; Baskaran, R.; Kubendran, T. R.

2012-12-01

55

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

SciTech Connect

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.

Hansen, A.R.; Kaminski, M.A. (Dept. of Chemical Engineering, Univ. of Illinois, Urbana, IL (US)); Eckert, C.A. (School of Chemical Engineering, Georgia Inst. of Technology, Atlanta, GA (US))

1990-04-01

56

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

PubMed

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

Tohka, Jussi

2014-11-28

57

Partial specific volume of cellulose N-phenyl carbamate  

NASA Astrophysics Data System (ADS)

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'.

Wohlfarth, Ch.

58

Partial breast irradiation: targeting volume or breast molecular subtypes?  

PubMed

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

Orecchia, Roberto; Leonardi, Maria Cristina

2013-08-01

59

The mesioangular third molar--to extract or not to extract? Analysis of 776 consecutive third molars.  

PubMed

Introduction Distal caries in lower second molars has been associated with mesioangular third molars. Caries detection and restoration can be difficult. If caries progresses, root canal treatment or extraction of the second molar can be necessary.Aims To identify the prevalence of caries in lower third molars and the distal aspect of corresponding lower second molars in patients referred for lower third molar assessment.Methods Analysis of OPG X-rays for 420 consecutive patients (776 third molars) referred to three maxillofacial centres over a five month period.Results Thirty-four percent of third molars were mesioangular. There was radiographic evidence of distal second molar caries in 42% of these. When unerupted mesioangular third molars were excluded this increased to 54%. There was no difference in age or dental health of these patients compared to the whole group. There was no angulation of the mesioangular third molar for which distal caries in the second molar was more likely.Conclusion Distal caries in lower second molars related to a mesioangular third molar is a common finding in oral and maxillofacial patients in secondary care, especially if the third molar is fully or partially erupted. If such a third molar is left in situ, close monitoring and regular bitewing radiographs are recommended. PMID:19498427

Allen, R T; Witherow, H; Collyer, J; Roper-Hall, R; Nazir, M A; Mathew, G

2009-06-13

60

Excess molar volumes, viscosities, and refractive indices for binary and ternary mixtures of {cyclohexanone (1) + N,N-dimethylacetamide (2) + N,N-diethylethanolamine (3)} at (298.15, 308.15, and 318.15) K  

Microsoft Academic Search

Densities ?, viscosities ?, and refractive indices nD, of the binary and ternary mixtures formed by cyclohexanone + N,N-dimethylacetamide + N,N-diethylethanolamine were measured at (298.15, 308.15, and 318.15)K for the liquid region and at ambient pressure for the whole composition ranges. The excess molar volumes VmE, viscosity deviations ??, and refractive index deviations ?nD, were calculated from experimental densities and

H. Iloukhani; M. Rakhshi

2009-01-01

61

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

Microsoft Academic Search

Molar heat capacities at constant volume (C{sub v}) of 1,1-difluoroethane (R152a) and 1,1,1-trifluoroethane (R143a) have been measured with an adiabatic calorimeter. Temperatures ranged from their triple points to 345 K, and pressures up to 35 MPa. Measurements were conducted on the liquid in equilibrium with its vapor and on compressed liquid samples. The samples were of high purity, verified by

Magee

1998-01-01

62

Molar Heat Capacity at Constant Volume of 1,1-Difluoroethane (R152a) and 1,1,1-Trifluoroethane (R143a) from the Triple-Point Temperature to 345 K at Pressures to 35 MPa  

Microsoft Academic Search

Molar heat capacities at constant volume (Cv) of 1,1-difluoroethane (R152a) and 1,1,1-trifluoroethane (R143a) have been measured with an adiabatic calorimeter. Temperatures ranged from their triple points to 345 K, and pressures up to 35 MPa. Measurements were conducted on the liquid in equilibrium with its vapor and on compressed liquid samples. The samples were of high purity, verified by chemical

J. W. Magee

1998-01-01

63

JOURNAL OF PETROLOGY VOLUME 39 NUMBER 6 PAGES 10911115 1998 Calculation of Peridotite Partial Melting from  

E-print Network

JOURNAL OF PETROLOGY VOLUME 39 NUMBER 6 PAGES 1091­1115 1998 Calculation of Peridotite Partial of peridotite using of the results of calculations of peridotite melting using MELTS, there are a number the suitability of this peridotite have more MgO and less SiO2 than equivalent ex- perimentally derived liquids

Asimow, Paul D.

64

Measurement of Radiotracer Concentration in Brain Gray Matter Using Positron Emission Tomography: MRI-Based Correction for Partial Volume Effects  

Microsoft Academic Search

Summary: Accuracy in in vivo quantitation of brain function with positron emission tomography (PET) has often been limited by partial volume effects. This limitation becomes prominent in studies of aging and degenerative brain diseases where partial volume effects vary with different degrees of atrophy. The present study describes how the actual gray matter (GM) tracer concentration can be estimated using

Hans W. Muller-Gartner; Jonathan M. Links; Jerry L. Prince; R. Nick Bryan; Elliot McVeigh; Jeffrey P. Leal; Christos Davatzikos; J. James Frost

1992-01-01

65

Excess molar heat capacities and excess molar volumes of (an n -alkylalkanoate + 2,2,4-trimethylpentane, or 2,2,4,4,6,8,8-heptamethylnonane) at T = 298.15 K  

Microsoft Academic Search

Excess molar heat capacities Cp, mEat constant pressure have been measured, as a function of mole fraction x at the temperature T= 298.15 K and atmospheric pressure, for eight liquid mixtures consisting of an n -alkylalkanoate and a highly-branched alkane {i.e. 2,2,4-trimethylpentane (isooctane) and 2,2,4,4,6,8,8-heptamethyl- nonane}: [xHCOO(CH2)3CH3+ (1 ?x){(CH3)3CCH2CH(CH3)2, or (CH3)3CCH2C(CH3)2CH2CH(CH3)CH2C(CH3)3} ], {xCH3COOCH2CH3+(1 ?x)(CH3)3CCH2CH(CH3)2}, {xCH3COO(CH2)3CH3+ (1 ?x)(CH3)3CCH2CH(CH3)2}, {xCH3CH2COOCH3+ (1 ?x)(CH3)3CCH2CH(CH3)2},

Emmerich Wilhelm

1999-01-01

66

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

NASA Astrophysics Data System (ADS)

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

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

2008-03-01

67

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

PubMed

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. PMID:23659770

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

2013-09-01

68

Interface profile studies in immiscible and partially miscible binary polymer blends from free volume measurement  

NASA Astrophysics Data System (ADS)

The diffused interface widths in an immiscible and a partially miscible polymer blend namely Polyvinyl chloride/Ethylene vinyl acetate (PVC/EVA) and Polystyrene/Polymethylmethacrylate (PS/PMMA) are experimentally measured and reported here. A new empirical relation found between hydrodynamic interaction parameter ? derived from free volume data and the Flory-Huggins interaction parameter ? is used to construct density profile across the interface to derive the interface width in above two binary blends.

Ramya, P.; Meghala, D.; Pasang, T.; Raj, J. M.; Ranganathaiah, C.; Williams, J. F.

2013-06-01

69

Investigation of partial volume correction methods for brain FDG PET studies  

SciTech Connect

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.

Yang, J.; Huang, S.C.; Mega, M.; Toga, A.W.; Small, G.W.; Phelps, M.E. [Univ. of California, Los Angeles, CA (United States)] [Univ. of California, Los Angeles, CA (United States); Lin, K.P. [Chung Yuan Christian Univ., Chung-Li (China). Dept. of Electrical Engineering] [Chung Yuan Christian Univ., Chung-Li (China). Dept. of Electrical Engineering

1996-12-01

70

Excess molar volumes and excess viscosities of the 2,2,4-trimethylpentane (1) + 3-methyl-1-butanol (2) and propan-2-ol (3) ternary system at 298.15 K  

Microsoft Academic Search

This paper reports experimental densities and viscosities of the ternary system 2-2-4-trimethylpentane+3-methyl-1-butanol+propan-2-ol and the binary systems 2-2-4-trimethylpentane (isooctane)+3-methyl-1-butanol (isoamyl alcohol), 2-2-4-trimethylpentane (isooctane)+propan-2-ol (isopropyl alcohol), and 3-methyl-1-butanol+propan-2-ol, over the entire range of composition at 298.15 K. Excess molar volume, excess viscosity and the excess energy of activation for viscous flow were evaluated from the experimental data obtained. These derived properties for

J. A. Salas; G. C. Pedrosa; I. L. Acevedo; E. L. Arancibia

2006-01-01

71

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

NASA Astrophysics Data System (ADS)

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.

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

2009-02-01

72

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

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. PMID:17192025

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

2005-06-01

73

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

SciTech Connect

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

Magee, J.W. [National Inst. of Standards and Technology, Boulder, CO (United States)] [National Inst. of Standards and Technology, Boulder, CO (United States)

1998-09-01

74

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

PubMed Central

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

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

2013-01-01

75

Acute and Short-Term Effects of Partial Left Ventriculectomy in Dilated Cardiomyopathy Assessment by Pressure-Volume Loops  

Microsoft Academic Search

OBJECTIVES The aim of this study was to evaluate the short-term effects of partial left ventriculectomy (PLV) on left ventricular (LV) pressure-volume (P-V) loops, wall stress, and the synchrony of LV segmental volume motions in patients with dilated cardiomyopathy. BACKGROUND Surgical LV volume reduction is under investigation as an alternative for, or bridge to, heart transplantation for patients with end-stage

Jan J. Schreuder; Paul Steendijk; Frederik H. van der Veen; Ottavio Alfieri; Theo van der Nagel; Roberto Lorusso; Jan-Melle van Dantzig; Kees B. Prenger; Jan Baan; Hein J. J. Wellens; Randas J. V. Batista

76

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

PubMed Central

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 [18F]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 [18F]DOPA utilization rates (kicer). Validation was first performed by measuring repeatability on test–retest scans. The precision of the methodologies instead was quantified using simulated [18F]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 kicer 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 kicer 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. PMID:23486292

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

2013-01-01

77

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

PubMed

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

Ahlgren, André; Wirestam, Ronnie; Petersen, Esben Thade; Ståhlberg, Freddy; Knutsson, Linda

2014-09-01

78

5-HT1A Receptors Are Reduced in Temporal Lobe Epilepsy After Partial-Volume Correction  

PubMed Central

Preclinical studies suggest that serotonin 1A receptors (5-HT1A) play a role in temporal lobe epilepsy (TLE). Previous PET studies reported decreased 5-HT1A binding ipsilateral to epileptic foci but did not correct for the partial-volume effect (PVE) due to structural atrophy. Methods: We used PET with 18F-trans-4-fluoro-N-2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl-N-(2-pyridyl)cyclohexanecarboxamide (18F-FCWAY), a 5-HT1A receptor antagonist, to study 22 patients with TLE and 10 control subjects. In patients, 18F-FDG scans also were performed. An automated MR-based partial-volume correction (PVC) algorithm was applied. Psychiatric symptoms were assessed with the Beck Depression Inventory Scale.Results: Before PVC, significant (uncorrected P<0.05) reductions of 18F-FCWAY binding potential (BP) were detected in both mesial and lateral temporal structures, mainly ipsilateral to the seizure focus, in the insula, and in the raphe. Group differences were maximal in ipsilateral mesial temporal regions (corrected P<0.05). After PVC, differences in mesial, but not lateral, temporal structures and in the insula remained highly significant (corrected P<0.05). Signifi-cant (uncorrected P<0.05) BP reductions were also detected in TLE patients with normal MR images (n = 6), in mesial temporal structures. After PVC, asymmetries in BP remained significantly greater than for glucose metabolism in hippocampus and parahippocampus. There was a significant inverse relation between the Beck Depression score and the ipsilateral hippocampal BP, both before and after PVC. Conclusion: Our study shows that in TLE patients, reductions of 5-HT1A receptor binding in mesial temporal structures and insula are still significant after PVC. In contrast, partial-volume effects may be an important contributor to 5-HT1A receptor-binding reductions in lateral temporal lobe. Reduction of 5-HT1A receptors in the ipsilateral hippocampus may contribute to depressive symptoms in TLE patients. PMID:16000281

Giovacchini, Giampiero; Toczek, Maria T.; Bonwetsch, Robert; Bagic, Anto; Lang, Lixin; Fraser, Charles; Reeves-Tyer, Pat; Herscovitch, Peter; Eckelman, William C.; Carson, Richard E.

2005-01-01

79

Diagnostic Value of Lectins in Differentiation of Molar Placentas  

PubMed Central

Objective(s) Distinction of hydatidiform moles from non-molar specimens and subclassification of hydatidiform moles as complete and partial are important for clinical practice, but diagnosis based solely on histomorphology suffers from poor interobserver reproducibility. Nowadays, pathologists rely on molecular techniques, however these methods are technically difficult, relatively expensive, and time consuming, and cannot be applied in all laboratories. Therefore, a relatively easy, time- and cost-effective ancillary tool, would be helpful. This study aimed to assess the role of lectins in differential diagnosis of molar placentas. Materials and Methods Lectin histochemistry with a panel of HRP-conjugated lectins comprising SBA, DBA, MPA, PNA, VVA, UEA-1, LTA, GS-? (B4), and WGA were performed in 20 non-molar (hydropic and non-hydropic spontaneous abortions) and 20 molar (partial and complete moles), formalin-fixed paraffin-embedded tissue samples. On the basis of staining intensity, sections were graded and Kruskal-Wallis non-parametric statistical test was used to compare differences between samples. Results There was a significant difference between the reactivities of LTA and UEA-? with syncytiotrophoblasts of molar and non-molar specimens (P<0.001). These lectins generally showed a moderate reactivity with syncytiotrophoblasts of molar group but did not react with this cell population in non-molar group. Furthermore, WGA showed relatively increased reaction with syncytiotrophoblasts of molar tissues compared with abortions, however, this did not reach to statistical significance (P=0.07). No major differences were seen in other lectins reactivities between the studied groups. Conclusion The present study showed that UEA-1 and LTA lectins may be used as cytochemical probes in differentiating molar from non-molar placentas, but did not differentiate partial moles from complete moles. PMID:23653842

Atabaki Pasdar, Fatemeh; Khooei, Alireza; Fazel, Alireza; Mahmoudi, Mahmoud; Nikravesh, Mohammad Reza; Khaje Delui, Mohammad

2012-01-01

80

Liquid Densities and Excess Molar Volumes for Binary Systems (Ionic Liquids?+?Methanol or Water) at 298.15, 303.15 and 313.15 K, and at Atmospheric Pressure  

Microsoft Academic Search

Binary excess molar volumes, V\\u000a \\u000a m\\u000a E, have been evaluated from density measurements, using a vibrating tube densimeter over the entire composition range for binary\\u000a liquid mixtures of ionic liquids 1-ethyl-3-methyl-imidazolium diethyleneglycol monomethylethersulphate [EMIM]+[CH3(OCH2CH2)2OSO3]? or 1-butyl-3-methyl-imidazolium diethyleneglycol monomethylethersulphate [BMIM]+[CH3(OCH2CH2)2OSO3]? or 1-methyl-3-octyl-imidazolium diethyleneglycol monomethylethersulphate [MOIM]+[CH3(OCH2CH2)2OSO3]?+methanol and [EMIM]+[CH3(OCH2CH2)2OSO3]?+water at 298.15, 303.15 and 313.15 K. The V\\u000a \\u000a m\\u000a E values were found to be negative

Pravena Bhujrajh; Nirmala Deenadayalu

2007-01-01

81

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

PubMed

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

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

2015-02-01

82

MRI-guided brain PET image filtering and partial volume correction  

NASA Astrophysics Data System (ADS)

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.

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

2015-02-01

83

Influence of mismatched CT anatomy on the accuracy of partial volume compensation in cardiac SPECT perfusion imaging  

Microsoft Academic Search

Necessary conditions for successful partial volume effect (PVE) compensation are: 1) a co-registered high-spatial resolution CT Map, 2) compensation for respiratory motion present in the emission data, and 3) Compton scatter compensation. The aim of this study was to determine what affect a mismatched CT Map will have on the accuracy of PVE compensated cardiac SPECT perfusion images. The MCAT

P. Hendrik Pretorius; Michael A King; P. P. Bruvant

2004-01-01

84

Comparative assessment of statistical brain MR image segmentation algorithms and their impact on partial volume correction in PET  

Microsoft Academic Search

Magnetic resonance imaging (MRI)-guided partial volume effect correction (PVC) in brain positron emission tomography (PET) is now a well-established approach to compensate the large bias in the estimate of regional radioactivity concentration, especially for small structures. The accuracy of the algorithms developed so far is, however, largely dependent on the performance of segmentation methods partitioning MRI brain data into its

Habib Zaidi; Torsten Ruest; Frederic Schoenahl; Marie-Louise Montandon

2006-01-01

85

Pseudo-rigid Body Modeling of IPMC for a Partially Compliant Four-bar Mechanism for Work Volume Generation  

Microsoft Academic Search

Conventional four-bar crank rocker mechanisms made of rigid links can generate only one path, at the rocker tip, for one revolution of the crank. However, if the rocker length can be actively changed then its tip can generate a work volume. This study describes an application of ionic polymer metal composite (IPMC) as a partially compliant rocker in a four-bar

Dibakar Bandopadhya; Bishakh Bhattacharya; Ashish Dutta

2009-01-01

86

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

SciTech Connect

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

Shaitelman, Simona F.; Vicini, Frank A.; Grills, Inga S.; Martinez, Alvaro A.; Yan Di [Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, MI (United States); Kim, Leonard H., E-mail: lkim@beaumonthospitals.com [Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, MI (United States)

2012-01-01

87

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

PubMed

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

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

2013-09-01

88

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

PubMed

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. PMID:24734018

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

2014-01-01

89

Evaluation of partial volume effect correction methods for brain positron emission tomography: Quantification and reproducibility  

PubMed Central

Quantitative accuracy of positron emission tomography (PET) is decreased by the partial volume effect (PVE). The PVE correction (PVC) methods proposed by Alfano et al., Rousset et al., Müller-Gärtner et al. and Meltzer et al. were evaluated in the present study to obtain guidelines for selecting among them. For accuracy evaluation, the Hoffman brain phantom was scanned with three PETs of differing spatial resolution in order to measure the effect of PVC on radioactivity distribution. Test-retest data consisting of duplicate dynamic emission recordings of the dopamine D2-receptor ligand [11C] raclopride obtained in eight healthy control subjects were used to test the correction effect in different regions of interest. The PVC method proposed by Alfano et al. gave the best quantification accuracy in the brain gray matter region. When the effect of PVC on reliability was tested with human data, the method of Meltzer et al. proved to be the most reliable. The method by Alfano et al. may be better for group comparison studies and the method by Meltzer et al. for intra-subject drug-effect studies. PMID:21157530

Harri, Merisaari; Mika, Teras; Jussi, Hirvonen; Nevalainen, Olli S.; Jarmo, Hietala

2007-01-01

90

A Theoretical Solution to MAP-EM Partial Volume Segmentation of Medical Images  

PubMed Central

Voxels near tissue borders in medical images contain useful clinical information, but are subject to severe partial volume (PV) effect, which is a major cause of imprecision in quantitative volumetric and texture analysis. When modeling each tissue type as a conditionally independent Gaussian distribution, the tissue mixture fractions in each voxel via the modeled unobservable random processes of the underlying tissue types can be estimated by maximum a posteriori expectation-maximization (MAP-EM) algorithm in an iterative manner. This paper presents, based on the assumption that PV effect could be fully described by a tissue mixture model, a theoretical solution to the MAP-EM segmentation algorithm, as opposed to our previous approximation which simplified the posteriori cost function as a quadratic term. It was found out that the theoretically-derived solution existed in a set of high-order non-linear equations. Despite of the induced computational complexity when seeking for optimum numerical solutions to non-linear equations, potential gains in robustness, consistency and quantitative precision were noticed. Results from both synthetic digital phantoms and real patient bladder magnetic resonance images were presented, demonstrating the accuracy and efficiency of the presented theoretical MAP-EM solution. PMID:19768123

Wang, Su; Lu, Hongyu; Liang, Zhengrong

2009-01-01

91

Bi-exponential magnetic resonance signal model for partial volume computation  

PubMed Central

Accurate quantification of small structures in magnetic resonance (MR) images is often limited by partial volume (PV) effects which arise when more than one tissue type is present in a voxel. PV may be critical when dealing with changes in brain anatomy as the considered structures such as gray matter (GM) are of the similar size as the MR spatial resolution. To overcome the limitations imposed by PV effects and achieve subvoxel accuracy different methods have been proposed. Here, we describe a method to compute PV by modeling the MR signal with a biexponential linear combination representing the contribution of at most two tissues in each voxel. In a first step, we estimated the parameters (T1, T2 and Proton Density) per tissue. Then, based on the bi-exponential formulation one can retrieve fractional contents by solving a linear system of two equations with two unknowns, namely tissue magnetizations. Preliminary tests were conducted on images acquired on a specially designed physical phantom for the study of PV effects. Further, the model was tested on BrainWeb simulated brain images to estimate GM and white matter (WM) PV effects. Root Mean Squared Error was computed between the BrainWeb ground truth and the obtained GM and WM PV maps. The proposed method outperformed traditionally used methods by 33% and 34% in GM and WM, respectively. PMID:23285556

Duché, Quentin; Acosta, Oscar; Gambarota, Giulio; Merlet, Isabelle; Salvado, Olivier; Saint-Jalmes, Hervé

2012-01-01

92

Partial-Volume Effect Correction in Positron Emission Tomography Brain Scan Image Using Superresolution Image Reconstruction.  

PubMed

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 (FWHM) spatial resolution of the imaging system. Objective: In the current study, the ability of superresolution (SR) image reconstruction to compensate for PVE in PET was characterized. Methods: The ability of the 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, the Hoffman brain phantom and in 4 human brain subjects (3 normal subjects and 1 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

Meechai, Tipvimol; Tepmongkol, Supatporn; Pluempitiwiriyawej, Charnchai

2014-12-10

93

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

SciTech Connect

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

Meltzer, C.C.; Zubieta, J.K.; Links, J.M. [Johns Hopkins Medical Institutions, Baltimore, MD (United States)] [and others

1994-05-01

94

Integrated Software for the Analysis of Brain PET\\/SPECT Studies with Partial-Volume-Effect Correction  

Microsoft Academic Search

We present software for integrated analysis of brain PET studies and coregistered segmented MRI that couples a module for automated placement of regions of interest (ROI) with 4 alter- native methods for partial-volume-effect correction (PVEc). The accuracy and precision of these methods have been measured using 4 simulated 18F-FDG PET studies with increasing degrees of atrophy. Methods: The software allows

Mario Quarantelli; Karim Berkouk; Anna Prinster; Brigitte Landeau; Claus Svarer; Laszlo Balkay; Bruno Alfano; Arturo Brunetti; Jean-Claude Baron; Marco Salvatore

2004-01-01

95

Surveillance without chemotherapy in a woman with recurrent molar pregnancy  

PubMed Central

A 27-year-old fouth gravida patient with previous two partial molar pregnancies and one missed abortion underwent a suction evacuation for partial molar pregnancy at 9?weeks of gestation. She was followed up with serum HCG values. Though the HCG level reduced from a pre-evacuation value of 1?40?223–31?157?mIU/ml 1?week post procedure, the levels continued to be positive in low titres 6?months after suction evacuation. The management options were discussed with the patient and a decision was taken to continue surveillance with serial HCG titres. HCG levels normalised after 11?months without the need for chemotherapy. PMID:23429019

Bagga, Rashmi; Siwatch, Sujata; Srinivasan, Radhika; Dhaliwal, Lakhbir Kaur

2013-01-01

96

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

PubMed Central

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 dramatic visual reduction in the impact of extracardiac activity, improved the uniformity of the normally perfused heart wall, and enhanced defect visibility without undue noise amplification. No significant artifacts were seen with PVE correction in the presence of mild (one voxel) misregistration. A statistically significant improvement in the accuracy of the count levels within the normal heart wall was also noted. However, residual spillover of counts from within the myocardium creates a bias in regions of decreased wall counts (perfusion defects?abnormal wall motion) when the anatomical imaging modality does not allow definition of templates for defects present in the heart during emission imaging. PMID:19235379

Pretorius, P. Hendrik; King, Michael A.

2009-01-01

97

Partial volume correction of PET-imaged tumor heterogeneity using expectation maximization with a spatially varying point spread function  

PubMed Central

Tumor heterogeneities observed in positron emission tomography (PET) imaging are frequently compromised of partial volume effects which may affect treatment prognosis, assessment, or future implementations such as biologically optimized treatment planning (dose painting). This paper presents a method for partial volume correction of PET-imaged heterogeneous tumors. A point source was scanned on a GE Discover LS at positions of increasing radii from the scanner’s center to obtain the spatially varying point spread function (PSF). PSF images were fit in three dimensions to Gaussian distributions using least squares optimization. Continuous expressions were devised for each Gaussian width as a function of radial distance, allowing for generation of the system PSF at any position in space. A spatially varying partial volume correction (SV-PVC) technique was developed using expectation maximization (EM) and a stopping criterion based on the method’s correction matrix generated for each iteration. The SV-PVC was validated using a standard tumor phantom and a tumor heterogeneity phantom, and was applied to a heterogeneous patient tumor. SV-PVC results were compared to results obtained from spatially invariant partial volume correction (SINV-PVC), which used directionally uniform three dimensional kernels. SV-PVC of the standard tumor phantom increased the maximum observed sphere activity by 55 and 40% for 10 and 13 mm diameter spheres, respectively. Tumor heterogeneity phantom results demonstrated that as net changes in the EM correction matrix decreased below 35%, further iterations improved overall quantitative accuracy by less than 1%. SV-PVC of clinically observed tumors frequently exhibited changes of ±30% in regions of heterogeneity. The SV-PVC method implemented spatially varying kernel widths and automatically determined the number of iterations for optimal restoration, parameters which are arbitrarily chosen in SINV-PVC. Comparing SV-PVC to SINV-PVC demonstrated that similar results could be reached using both methods, but large differences result for the arbitrary selection of SINV-PVC parameters. The presented SV-PVC method was performed without user intervention, requiring only a tumor mask as input. Research involving PET-imaged tumor heterogeneity should include correcting for partial volume effects to improve the quantitative accuracy of results. PMID:20009194

Barbee, David L; Flynn, Ryan T; Holden, James E; Nickles, Robert J; Jeraj, Robert

2010-01-01

98

A novel neutron computed tomography partial volume voxel water quantification technique  

NASA Astrophysics Data System (ADS)

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

Heller, Arthur Kevin

99

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

PubMed

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

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

2015-01-01

100

Molarization of Mandibular Second Premolar  

PubMed Central

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

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

2014-01-01

101

Solutions : WtPercentToMolarity (4 Variations)  

NSDL National Science Digital Library

A common concentration unit used commercially is percent weight per volume (%W/V) which is the number of grams of solute in 100 mL of solution. A bottle of vinegar contains 5 %W/V acetic acid (CH 3 COOH). What is the molar concentration of acetic acid in the vinegar?

102

Influence of partial volume correction in staging of head and neck squamous cell carcinoma using PET/CT.  

PubMed

Aim: PET/CT is widely used for the detection of lymph node involvement in head and neck squamous cell carcinoma (HNSCC). However, PET qualitative and quantitative capabilities are hindered by partial volume effects (PVE). Therefore, a retrospective study on 32 patients (57 lymph nodes) was carried out to evaluate the potential improvement of PVE correction (PVEC) in FDG PET/CT imaging for the diagnosis of HNSCC. Histopathological analysis of lymph nodes following neck dissection was used as the gold standard. Methods: A previously proposed deconvolution based PVEC approach was used to derive improved quantitative accuracy PET images, while the anatomical lymph node volumes were determined on the CT images. Different parameters including SUVmax and SUVmean were derived from both original and PVEC PET images for each patient. Results: Histopathology confirmed that SUVmax and SUVmean after PVEC allows a statistically significant differentiation of malignant and benign lymph nodes (p<0.05). The sensitivity of SUVmax and SUVmean was 64% and 57% respectively with or without PVEC. PVEC increased specificity from 71% to 76% for SUVmax and 57% to 66% for SUVmean. Corresponding accuracy increased from 66% to 71% for SUVmax and from 59% to 66% for SUVmean. However, the most accurate differentiation between benign and malignant nodes was obtained while using the magnitude of SUVmax increase after PVEC with a corresponding sensitivity, specificity and accuracy of 77%, 82% and 80% respectively. Conclusion: Our work shows that the use of partial volume effects correction allows a more accurate nodal staging using FDG PET imaging in HNSCC. PMID:24309537

Fayad, H; Le Pogam, A; Lamare, F; Fernandez, P; Pradier, O; Valette, G; Visvikis, D; Cheze Le Rest, C

2013-12-01

103

How Neanderthal molar teeth grew  

Microsoft Academic Search

Growth and development are both fundamental components of demographic structure and life history strategy. Together with information about developmental timing they ultimately contribute to a better understanding of Neanderthal extinction. Primate molar tooth development tracks the pace of life history evolution most closely, and tooth histology reveals a record of birth as well as the timing of crown and root

Roberto Macchiarelli; Luca Bondioli; André Debénath; Arnaud Mazurier; Jean-François Tournepiche; Wendy Birch; M. Christopher Dean

2006-01-01

104

Quantification of human high-energy phosphate metabolite concentrations at 3 T with partial volume and sensitivity corrections.  

PubMed

Practical noninvasive methods for the measurement of absolute metabolite concentrations are key to the assessment of the depletion of myocardial metabolite pools which occurs with several cardiac diseases, including infarction and heart failure. Localized MRS offers unique noninvasive access to many metabolites, but is often confounded by nonuniform sensitivity and partial volume effects in the large, poorly defined voxels commonly used for the detection of low-concentration metabolites with surface coils. These problems are exacerbated at higher magnetic field strengths by greater radiofrequency (RF) field inhomogeneity and differences in RF penetration with heteronuclear concentration referencing. An example is the (31)P measurement of cardiac adenosine triphosphate (ATP) and phosphocreatine (PCr) concentrations, which, although central to cardiac energetics, have not been measured at field strengths above 1.5 T. Here, practical acquisition and analysis protocols are presented for the quantification of [PCr] and [ATP] with one-dimensionally resolved surface coil spectra and concentration referencing at 3 T. The effects of nonuniform sensitivity and partial tissue volumes are addressed at 3 T by the application of MRI-based three-dimensional sensitivity weighting and tissue segmentation. The method is validated in phantoms of different sizes and concentrations, and used to measure [PCr] and [ATP] in healthy subjects. In calf muscle (n = 8), [PCr] = 24.7 ± 3.4 and [ATP] = 5.7 ± 1.3 µmol/g wet weight, whereas, in heart (n = 18), [PCr] = 10.4 ± 1.5 and [ATP] = 6.0 ± 1.1 µmol/g wet weight (all mean ± SD), consistent with previous reports at lower fields. The method enables, for the first time, the efficient, semi-automated quantification of high-energy phosphate metabolites in humans at 3 T with nonuniform excitation and detection. PMID:23729378

El-Sharkawy, Abdel-Monem M; Gabr, Refaat E; Schär, Michael; Weiss, Robert G; Bottomley, Paul A

2013-11-01

105

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

PubMed

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

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

2013-10-01

106

Comparing a volume based template approach and ultrasound guided freehand approach in multicatheter interstitial accelerated partial breast irradiation  

PubMed Central

Purpose Currently, there are two described methods of catheter insertion for women undergoing multicatheter interstitial accelerated partial breast irradiation (APBI). These are a volume based template approach (template) and a non-template ultrasound guidance freehand approach (non-template). We aim to compare dosimetric endpoints between the template and non-template approach. Material and methods Twenty patients, who received adjuvant multicatheter interstitial APBI between August 2008 to March 2010 formed the study cohort. Dosimetric planning was based on the RTOG 04-13 protocol. For standardization, the planning target volume evaluation (PTV-Eval) and organs at risk were contoured with the assistance of the attending surgeon. Dosimetric endpoints include D90 of the PTV-Eval, Dose Homogeneity Index (DHI), V200, maximum skin dose (MSD), and maximum chest wall dose (MCD). A median of 18 catheters was used per patient. The dose prescribed was 34 Gy in 10 fractions BID over 5 days. Results The average breast volume was 846 cm3 (526-1384) for the entire cohort and there was no difference between the two groups (p = 0.6). Insertion time was significantly longer for the non-template approach (mean 150 minutes) compared to the template approach (mean: 90 minutes) (p = 0.02). The planning time was also significantly longer for the non-template approach (mean: 240 minutes) compared to the template approach (mean: 150 minutes) (p < 0.01). The template approach yielded a higher D90 (mean: 95%) compared to the non-template approach (mean: 92%) (p < 0.01). There were no differences in DHI (p = 0.14), V200 (p = 0.21), MSD (p = 0.7), and MCD (p = 0.8). Conclusions Compared to the non-template approach, the template approach offered significant shorter insertion and planning times with significantly improved dosimetric PTV-Eval coverage without significantly compromising organs at risk dosimetrically. PMID:25097558

Koh, Vicky Y.; Buhari, Shaik A.; Tan, Poh Wee; Tan, Yun Inn; Leong, Yuh Fun; Earnest, Arul

2014-01-01

107

Improved Regional Activity Quantitation in Nuclear Medicine using a New Approach to Correct for Tissue Partial Volume and Spillover Effects  

PubMed Central

We have developed a new method of compensating for effects of partial volume and spillover in dual-modality imaging. The approach requires segmentation of just a few tissue types within a small VOI surrounding a lesion; the algorithm estimates simultaneously, from projection data, the activity concentration within each segmented tissue inside the VOI. Measured emission projections were fitted to the sum of resolution-blurred projections of each such tissue, scaled by its unknown activity concentration, plus a global background contribution obtained by reprojection through the reconstructed image volume outside the VOI. The method was evaluated using multiple-pinhole ?SPECT data simulated for the MOBY mouse phantom containing two spherical lung tumors and one liver tumor, as well as using multiple-bead phantom data acquired on ?SPECT and ?CT scanners. Each VOI in the simulation study was 4.8 mm (12 voxels) cubed and, depending on location, contained up to four tissues (tumor, liver, heart, lung) with different values of relative 99mTc concentration. All tumor activity estimates achieved <3% bias after ~15 OSEM iterations (× 10 subsets), with better than 8% precision (?25% greater than the Cramer-Rao lower bound). The projection-based fitting approach also outperformed three SUV-like metrics, one of which was corrected for count spillover. In the bead phantom experiment, the mean ± standard deviation of the bias of VOI estimates of bead concentration were 0.9 ± 9.5%, comparable to those of a perturbation geometric transfer matrix (pGTM) approach (-5.4 ± 8.6%); however, VOI estimates were more stable with increasing iteration number than pGTM estimates, even in the presence of substantial axial misalignment between ?CT and ?SPECT image volumes. PMID:21965196

Moore, Stephen C.; Southekal, Sudeepti; Park, Mi-Ae; McQuaid, Sarah J.; Kijewski, Marie Foley; Müller, Stefan P.

2013-01-01

108

Mesial force from unerupted third molars  

Microsoft Academic Search

TOP Erupting mandibular third molars are implicated as a cause of anterior crowding of mandibular teeth. The goal of this two-part investigation was to measure the mesial force exerted by unerupted mandibular third molars. We hypothesized that such a force increases the tightness of all proximal posterior tooth contacts mesial to the mandibular second molar, and that surgical removal of

Thomas E. Southard; Karin A. Southard; Larry W. Weeda

1991-01-01

109

Volume 277, number 1,2, 127-130 F'EBS09249 December 1990 Partial reversion of the electrogenic reaction in the ubiquinol  

E-print Network

Volume 277, number 1,2, 127-130 F'EBS09249 December 1990 Partial reversion of the electrogenic to the primary donor P. The other electron moves via the low-potential heme br and the high-potential heme bh

Steinhoff, Heinz-Jürgen

110

Partial volume effect correction in PET using regularized iterative deconvolution with variance control based on local topology  

NASA Astrophysics Data System (ADS)

Correcting positron emission tomography (PET) images for the partial volume effect (PVE) due to the limited resolution of PET has been a long-standing challenge. Various approaches including incorporation of the system response function in the reconstruction have been previously tested. We present a post-reconstruction PVE correction based on iterative deconvolution using a 3D maximum likelihood expectation-maximization (MLEM) algorithm. To achieve convergence we used a one step late (OSL) regularization procedure based on the assumption of local monotonic behavior of the PET signal following Alenius et al. This technique was further modified to selectively control variance depending on the local topology of the PET image. No prior 'anatomic' information is needed in this approach. An estimate of the noise properties of the image is used instead. The procedure was tested for symmetric and isotropic deconvolution functions with Gaussian shape and full width at half-maximum (FWHM) ranging from 6.31 mm to infinity. The method was applied to simulated and experimental scans of the NEMA NU 2 image quality phantom with the GE Discovery LS PET/CT scanner. The phantom contained uniform activity spheres with diameters ranging from 1 cm to 3.7 cm within uniform background. The optimal sphere activity to variance ratio was obtained when the deconvolution function was replaced by a step function few voxels wide. In this case, the deconvolution method converged in ~3-5 iterations for most points on both the simulated and experimental images. For the 1 cm diameter sphere, the contrast recovery improved from 12% to 36% in the simulated and from 21% to 55% in the experimental data. Recovery coefficients between 80% and 120% were obtained for all larger spheres, except for the 13 mm diameter sphere in the simulated scan (68%). No increase in variance was observed except for a few voxels neighboring strong activity gradients and inside the largest spheres. Testing the method for patient images increased the visibility of small lesions in non-uniform background and preserved the overall image quality. Regularized iterative deconvolution with variance control based on the local properties of the PET image and on estimated image noise is a promising approach for partial volume effect corrections in PET.

Kirov, A. S.; Piao, J. Z.; Schmidtlein, C. R.

2008-05-01

111

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

NASA Astrophysics Data System (ADS)

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

Mille, Matthew M.

112

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

PubMed

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

Clegg, S L; Wexler, A S

2011-04-21

113

[Hyperthyroidism induced by molar pregnancy].  

PubMed

A case is reported of a Senegalese patient admitted for hydatiform mole. The serum human chorionic gonadotrophin concentration (hCG) was 900,000 UI.l-1. The patient was recognized to be clinically hyperthyroid with raised T4 and T3 values, but a very low TSH concentration. After two days of beta adrenergic blockade and carbimazole, a suction curettage was performed under general anaesthesia. Propranolol was again administered 6 hours after the surgery. Thyroid function returned to normal level two weeks after removal of the mole, suggesting that hCG was responsible for the thyrotoxicosis. Serum hCG concentrations closely paralleled those of free thyroxine, but the correlation was difficult to assess because of carbimazole. Clinical thyrotoxicosis is rare in molar pregnancy. The diagnosis being made in semi-urgent conditions, this raises the question of how to obtain rapid stabilization of the disease before surgery. PMID:8273931

Laurent, V; Besson, L; Doussin, J F; Rondelet, B; Banssillon, V

1993-01-01

114

Results of intentional replantation of molars  

Microsoft Academic Search

Purpose: This study evaluated the treatment outcome of intentional replantation of molars.Patients and Methods: Twenty-nine patients were treated with intentional replantation because conventional apicoectomy was not possible. The success rate was judged by clinical and radiographic parameters.Results: One molar (3%) had to be removed because of pain and mobility 4 weeks postsurgery, and three molars (11%) had to be removed

Gerry M Raghoebar; Arjan Vissink

1999-01-01

115

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

PubMed

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

Sivakumar, Indumathi; Sivakumar, Arunachalam

2014-07-01

116

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

PubMed Central

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

Sivakumar, Indumathi; Sivakumar, Arunachalam

2014-01-01

117

Molar Malocclusions in Pine Voles (Microtus pinetorum)  

PubMed Central

Here we describe 5 cases of molar malocclusions in adult pine voles (Microtus pinetorum) used for behavioral endocrinology studies. This species belongs to the subfamily Microtinae, which possess aradicular hypsodont molars. The abnormal molars identified caused apparent difficulty in mastication, resulting in poor body condition necessitating euthanasia. Postmortem examination of the oral cavity revealed grossly elongated mandibular and maxillary molars with abnormal wear at occlusal surfaces. This colony health problem was addressed successfully by adding autoclaved hardwood sticks to each cage as an enrichment tool. PMID:19653952

Harvey, Stephen B; Alworth, Leanne C; Blas-Machado, Uriel

2009-01-01

118

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

NASA Astrophysics Data System (ADS)

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.

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

2012-07-01

119

Evaluation of a 3D local multiresolution algorithm for the correction of partial volume effects in positron emission tomography  

PubMed Central

Purpose Partial volume effects (PVE) are consequences of the limited spatial resolution in emission tomography leading to under-estimation of uptake in tissues of size similar to the point spread function (PSF) of the scanner as well as activity spillover between adjacent structures. Among PVE correction methodologies, a voxel-wise mutual multi-resolution analysis (MMA) was recently introduced. MMA is based on the extraction and transformation of high resolution details from an anatomical image (MR/CT) and their subsequent incorporation into a low resolution PET image using wavelet decompositions. Although this method allows creating PVE corrected images, it is based on a 2D global correlation model which may introduce artefacts in regions where no significant correlation exists between anatomical and functional details. Methods A new model was designed to overcome these two issues (2D only and global correlation) using a 3D wavelet decomposition process combined with a local analysis. The algorithm was evaluated on synthetic, simulated and patient images, and its performance was compared to the original approach as well as the geometric transfer matrix (GTM) method. Results Quantitative performance was similar to the 2D global model and GTM in correlated cases. In cases where mismatches between anatomical and functional information were present the new model outperformed the 2D global approach, avoiding artefacts and significantly improving quality of the corrected images and their quantitative accuracy. Conclusions A new 3D local model was proposed for a voxel-wise PVE correction based on the original mutual multi-resolution analysis approach. Its evaluation demonstrated an improved and more robust qualitative and quantitative accuracy compared to the original MMA methodology, particularly in the absence of full correlation between anatomical and functional information. PMID:21978037

Le Pogam, Adrien; Hatt, Mathieu; Descourt, Patrice; Boussion, Nicolas; Tsoumpas, Charalampos; Turkheimer, Federico E.; Prunier-Aesch, Caroline; Baulieu, Jean-Louis; Guilloteau, Denis; Visvikis, Dimitris

2011-01-01

120

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

EPA Science Inventory

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

121

Antibiotics in third molar surgery.  

PubMed

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

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

2014-01-01

122

Role of third molars in orthodontics  

PubMed Central

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

Almpani, Konstantinia; Kolokitha, Olga-Elpis

2015-01-01

123

Role of third molars in orthodontics.  

PubMed

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

Almpani, Konstantinia; Kolokitha, Olga-Elpis

2015-02-16

124

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

PubMed Central

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

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

2011-01-01

125

Third molars: a threat to periodontal health??  

PubMed

The third molars have received the fair amount of interest in literature. It has been blamed for problems such as-lower incisor crowding, atypical facial pain, caries etc. They are considered as 'waste bins' in dental practices as they are regarded as functionally non-essential. While making the clinical decision, they are given less importance and often extraction is considered to be the treatment option. Despite periodontal problems that can arise with extracted third molars, retention of third molars can also lead to periodontal problems with the adjacent teeth in addition to teeth farther to third molars. Of late, it is very important to consider the periodontal problems while making the clinical decision. This review paper has been discussed keeping this as prime objective. PMID:23730073

Kaveri, G S; Prakash, Shobha

2012-06-01

126

Lingual exposure during mandibular third molar surgery.  

PubMed

The necessity for surgical exposure of the lingual aspect of mandibular third molars will vary according to the severity of the impaction and the surgical technique adopted. A retractor is described for use in those cases when major lingual retraction is required. The retractor provides optimum access to the mandibular third molar area with adequate protection for the lingual nerve, tongue retraction and enhanced illumination by light reflection. It can be used under both local and general anaesthesia. PMID:415017

Stacy, G C

1977-12-01

127

Efficiency of a pendulum appliance for molar distalization related to second and third molar eruption stage  

Microsoft Academic Search

A modified pendulum appliance, including a distal screw and special preactivated pendulum springs (built-in straightening activation and toe-in bending), was used for bilateral maxillary molar distalization in 36 adolescent patients in various stages of the molar dentition. The patients were divided into 3 groups (PG 1-3) according to the stage of eruption of their second and third molars. In PG

Gero S. M Kinzinger; Ulrike B Fritz; Franz-Günter Sander; Peter R Diedrich

2004-01-01

128

Volume  

NSDL National Science Digital Library

This interactive applet demonstrates volume as the number of unit cubes needed to fill a rectangular solid. The learner sees an animation and answers questions about the capacity of a box. The student can then ask for other problems where just the 3D dimensions are given and the volume is requested.

2011-01-01

129

Uncertainty assessment of Si molar mass measurements  

NASA Astrophysics Data System (ADS)

The uncertainty of the Si molar mass measurement is theoretically investigated by means of a two-isotope model, with particular emphasis to the role of this measurement in the determination of the Avogadro constant. This model allows an explicit calibration formula to be given and propagation of error analysis to be made. It also shows that calibration cannot correct for non-linearity.

Mana, G.; Massa, E.; Valkiers, S.; Willenberg, G.-D.

2010-01-01

130

Molar and molecular views of choice  

Microsoft Academic Search

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

William M Baum

2004-01-01

131

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

SciTech Connect

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

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

2011-03-01

132

Partial Eval Partial Eval  

E-print Network

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Sumii, Eijiro

133

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

SciTech Connect

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

Leonard, Kara Lynne, E-mail: karalynne.kerr@gmail.com [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States); Hepel, Jaroslaw T. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States) [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States); Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island (United States); Hiatt, Jessica R. [Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island (United States)] [Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island (United States); Dipetrillo, Thomas A. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States) [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States); Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island (United States); Price, Lori Lyn [Department of Biostatistics Research Center, Institute of Clinical Research and Health Policy Studies, Tufts Medical Center, Boston, Massachusetts (United States)] [Department of Biostatistics Research Center, Institute of Clinical Research and Health Policy Studies, Tufts Medical Center, Boston, Massachusetts (United States); Wazer, David E. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States) [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States); Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island (United States)

2013-03-01

134

Design and Implementation of an Automated Partial Volume Correction in PET: Application to Dopamine Receptor Quantification in the Normal Human Striatum  

PubMed Central

The considerable effort and potential lack of reproducibility of human-driven PET quantification and partial volume correction (PVC) can be alleviated by use of atlas-based automatic analysis. The present study examined the application of a new algorithm designed to automatically define 3-dimensional regions of interest (ROIs) and their effect on dopamine receptor quantification in the normal human brain striatum, both without and with PVC. Methods A total of 90 healthy volunteers (age range, 18–46 y) received a single injection of 11C-raclopride, and automatic segmentation of concomitant structural MR images was performed using a maximum-probability atlas in combination with a trained neural network. For each identified tissue segment considered homogeneous for the tracer (or volumes of interest [VOIs]), an a priori criterion based on minimum axial recovery coefficient (RCzmin = 50%, 75%, and 90%) was used to constrain the extent of each ROI. Results With ROIs essentially overlapping the entire VOI volume (obtained with RCzmin = 50%), the binding potential (BPND) of 11C-raclopride was found to be around 2.2 for caudate and 2.9 for putamen, an underestimation by 35% and 28%, respectively, according to PVC values. At increased RCzmin, BPND estimates of 11C-raclopride were increased by 12% and 21% for caudate and 8% and 15% for putamen when the associated ROIs decreased to around 65% and 43% of total tissue volume (VOI) for caudate and 67% and 31% for putamen. After PVC, we observed relative increases in BPND variance of 12% for caudate and 20% for putamen, whereas estimated BPND values all increased to 3.4 for caudate and 4.0 for putamen, regardless of ROI size. Dopamine receptor concentrations appeared less heterogeneous in the normal human striatum after PVC than they did without PVC: the 25%–30% difference in BPND estimates observed between caudate and putamen remained significant after PVC but was reduced to slightly less than 20%. Furthermore, the results were comparable with those obtained with a manual method currently in use in our laboratory. Conclusion The new algorithm allows for traditional PET data extraction and PVC in an entirely automatic fashion, thus avoiding labor-intensive analyses and potential intra- or interobserver variability. This study also offers the first, to our knowledge, large-scale application of PVC to dopamine D2/D3 receptor imaging with 11C-raclopride in humans. PMID:18552147

Rousset, Olivier G.; Collins, D. Louis; Rahmim, Arman; Wong, Dean F.

2011-01-01

135

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

SciTech Connect

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.

Nguyen, Brandon T., E-mail: Brandon.Nguyen@act.gov.au [Department of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Canberra Hospital, Radiation Oncology Department, Garran, ACT (Australia); Deb, Siddhartha [Department of Anatomical Pathology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia) [Department of Anatomical Pathology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Victorian Cancer Biobank, Cancer Council of Victoria, Carlton, Victoria (Australia); Fox, Stephen [Department of Anatomical Pathology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia)] [Department of Anatomical Pathology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Hill, Prudence [Department of Anatomical Pathology, St. Vincent's Hospital Melbourne, Fitzroy, Victoria (Australia)] [Department of Anatomical Pathology, St. Vincent's Hospital Melbourne, Fitzroy, Victoria (Australia); Collins, Marnie [Centre for Biostatistics and Clinical Trials, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia)] [Centre for Biostatistics and Clinical Trials, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Chua, Boon H. [Department of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia) [Department of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); University of Melbourne, Parkville, Victoria (Australia)

2012-12-01

136

Positional changes of the third molar in orthodontically treated patients  

PubMed Central

Objective and Rationale. Over the years, the effects of the third molars eruption on the dental arches have been studied extensively. Still, literature provides less data regarding the effects of the orthodontic treatment on the third molars position. The aim of our study was to assess the positional changes of the third molars relative to the occlusal plane and to the second molar long axis, changes occurred during orthodontic treatment performed with or without premolar extractions. Method. This study included 20 orthodontic treated patients: 10 of them with premolar extractions and 10 without premolar extractions. The pretreatment and post treatment panoramic radiographs were analyzed, and the angles between the third molar long axis and the occlusal plane and between the long axis of the third molar and the long axis of the second molar were measured. Results. Changes in third molar position, from pretreatment to post treatment, for the two groups of patients were evaluated by using the Student’s t-test. The results of the statistical analysis revealed an improvement in third molars position, the best results were seen in the lower third molars, in the group of patients treated with premolar extractions. PMID:23904878

Mihai, AM; Lulache, IR; Grigore, R; Sanabil, AS; Boiangiu, S; Ionescu, E

2013-01-01

137

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

PubMed

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

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

2015-03-01

138

Quantification of opioid receptor availability following spontaneous epileptic seizures: correction of [11C]diprenorphine PET data for the partial-volume effect.  

PubMed

Previous positron emission tomography (PET) studies in refractory temporal lobe epilepsy (TLE) using the non-selective opioid receptor antagonist [(11)C]diprenorphine (DPN) did not detect any changes in mesial temporal structures, despite known involvement of the hippocampus in seizure generation. Normal binding in smaller hippocampi is suggestive of increased receptor concentration in the remaining grey matter. Correction for partial-volume effect (PVE) has not been used in previous DPN PET studies. Here, we present PVE-corrected DPN-PET data quantifying post-ictal and interictal opioid receptor availability in humans with mTLE. Eight paired datasets of post-ictal and interictal DPN PET scans and eleven test/retest control datasets were available from a previously published study on opioid receptor changes in TLE following seizures (Hammers et al., 2007a). Five of the eight participants with TLE had documented hippocampal sclerosis. Data were re-analyzed using regions of interest and a novel PVE correction method (structural functional synergistic-resolution recovery (SFS-RR); (Shidahara et al., 2012)). Data were denoised, followed by application of SFS-RR, with anatomical information derived via precise anatomical segmentation of the participants' MRI (MAPER; (Heckemann et al., 2010)). [(11)C]diprenorphine volume-of-distribution (VT) was quantified in six regions of interest. Post-ictal increases were observed in the ipsilateral fusiform gyri and lateral temporal pole. A novel finding was a post-ictal increase in [(11)C]DPN VT relative to the interictal state in the ipsilateral parahippocampal gyrus, not observed in uncorrected datasets. As for voxel-based (SPM) analyses, correction for global VT values was essential in order to demonstrate focal post-ictal increases in [(11)C]DPN VT. This study provides further direct human in vivo evidence for changes in opioid receptor availability in TLE following seizures, including changes that were not evident without PVE correction. Denoising, resolution recovery and precise anatomical segmentation can extract valuable information from PET studies that would be missed with conventional post-processing procedures. PMID:23597934

McGinnity, Colm J; Shidahara, Miho; Feldmann, Maria; Keihaninejad, Shiva; Riaño Barros, Daniela A; Gousias, Ioannis S; Duncan, John S; Brooks, David J; Heckemann, Rolf A; Turkheimer, Federico E; Hammers, Alexander; Koepp, Matthias J

2013-10-01

139

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

PubMed

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

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

2012-07-13

140

Can a partial volume edge effect reduction algorithm improve the repeatability of subject-specific finite element models of femurs obtained from CT data?  

PubMed

The reliability of patient-specific finite element (FE) modelling is dependent on the ability to provide repeatable analyses. Differences of inter-operator generated grids can produce variability in strain and stress readings at a desired location, which are magnified at the surface of the model as a result of the partial volume edge effects (PVEEs). In this study, a new approach is introduced based on an in-house developed algorithm which adjusts the location of the model's surface nodes to a consistent predefined threshold Hounsfield unit value. Three cadaveric human femora specimens were CT scanned, and surface models were created after a semi-automatic segmentation by three different experienced operators. A FE analysis was conducted for each model, with and without applying the surface-adjustment algorithm (a total of 18 models), implementing identical boundary conditions. Maximum principal strain and stress and spatial coordinates were probed at six equivalent surface nodes from the six generated models for each of the three specimens at locations commonly utilised for experimental strain guage measurement validation. A Wilcoxon signed-ranks test was conducted to determine inter-operator variability and the impact of the PVEE-adjustment algorithm. The average inter-operator difference in stress values was significantly reduced after applying the adjustment algorithm (before: 3.32 ± 4.35 MPa, after: 1.47 ± 1.77 MPa, p = 0.025). Strain values were found to be less sensitive to inter-operative variability (p = 0.286). In summary, the new approach as presented in this study may provide a means to improve the repeatability of subject-specific FE models of bone obtained from CT data. PMID:22452517

Peleg, Eran; Herblum, Ryan; Beek, Maarten; Joskowicz, Leo; Liebergall, Meir; Mosheiff, Rami; Whyne, Cari

2014-01-01

141

Effect of partial volume correction on estimates of the influx and cerebral metabolism of 6-[(18)F]fluoro-L-dopa studied with PET in normal control and Parkinson's disease subjects.  

PubMed

The poor spatial resolution of positron emission tomography (PET) is a limiting factor in the accurate assay of physiological processes investigated by compartmental modeling of tracer uptake and metabolism in living human brain. The radioactivity concentration in a region-of-interest is consequently altered by loss of signal from that structure and contamination from adjacent brain regions, phenomena known as partial volume effects. We now apply an MRI-based algorithm to compensate for partial volume effects in the special case of compartmental modeling of the cerebral uptake of 6-[(18)F]fluoro-L-dopa (FDOPA), an exogenous substrate of dopa decarboxylase. High-resolution MRI scans were obtained from normal volunteers (n = 4) and patients with Parkinson's disease (n = 4) in order to segment specific brain regions and calculate the partial volume correction factors. Dynamic 2D PET scans were acquired during 90 min following intravenous infusion of FDOPA. After partial volume correction, the apparent net blood-brain clearance of FDOPA (K(i)) was greatly increased in caudate and putamen of normal subjects and in caudate of Parkinson's disease patients. The equilibrium distribution volume of FDOPA (V(D)(e)) in cerebral cortex increased by 35% in all subjects. Using a two-compartment model, the relative activity of dopa decarboxylase with respect to FDOPA (k(D)(3)) in the basal ganglia was increased 2-3 times in normal subjects, to the range obtained previously in brain of living rat. The partial volume correction also increased the magnitude of k(D)(3) in caudate of Parkinson's disease patients, but did not alter k(D)(3) in putamen. A three-compartment model correcting for elimination of decarboxylated metabolites also yielded higher estimates of k(D)(3), but with a penalty in precision of the estimates. Together, these observations suggest that the limited spatial resolution of PET results in substantial underestimation of the true rate of FDOPA uptake and metabolism in vivo, and may also tend to obscure regional heterogeneity in the neurochemical pathology of Parkinson's disease. PMID:10881028

Rousset, O G; Deep, P; Kuwabara, H; Evans, A C; Gjedde, A H; Cumming, P

2000-08-01

142

Complications after apicoectomy in maxillary premolar and molar teeth  

Microsoft Academic Search

This study was designed to enumerate the number of perforations to the maxillary sinus while performing apicoectomy on maxillary premolar and molar teeth and to evaluate possible complications as a result of these perforations. A total of 472 apicoectomies were performed in 440 patients; perforations occurred in 10.4% of teeth, 23% in molars, 13% in second premolars and 2% in

Alan Freedman; Isack Horowitz

1999-01-01

143

RESEARCH Open Access Half-molar sodium lactate infusion improves  

E-print Network

RESEARCH Open Access Half-molar sodium lactate infusion improves cardiac performance in acute heart for the myocardium at rest and during stress. We tested the effects of half-molar sodium lactate infusion on cardiac by 1 ml/kg/h continuous infusion for 24 hours. The control group received only a 3 ml/kg bolus

Paris-Sud XI, Université de

144

Finite element analysis of mandibular molar protraction mechanics using miniscrews.  

PubMed

Summary BACKGROUND/OBJECTIVES: The aim of this study was to determine the most desirable force system to achieve molar protraction from an interdental miniscrew minimizing side-effects. Several iterations of force delivery were simulated through variations in the height of a miniscrew, length of a molar extension arm, and incorporation of a lingual force. PMID:25005109

Nihara, Jun; Gielo-Perczak, Krystyna; Cardinal, Lucas; Saito, Isao; Nanda, Ravindra; Uribe, Flavio

2014-07-01

145

Impaction of Permanent Mandibular Second Molars in Ethnic Chinese Schoolchildren  

Microsoft Academic Search

Objective: ?To investigate the prevalence of impaction of permanent mandibular second molars and associated dental and radiographic characteristics of Chinese children in Hong Kong. MaterialsandMethods: ?Dental and radiographic records of a group of Chinese school- children were studied retrospectively. Cases of impaction of 1 or both permanent man- dibular second molars were selected. Demographic data and dental and radiographic findings

Shiu-yin Cho; Yung Ki; Vanessa Chu; Joseph Chan

146

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)

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

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

2013-10-01

147

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

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 most cases compared to the other PVC methods. The results indicate that the PVC implementation and choice of PSF modelling in the reconstruction can significantly impact model parameters. PMID:24052021

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

2013-10-21

148

Presence of third molars in orthodontic patients from northern Greece  

PubMed Central

Objective The purpose of the present study was to investigate the frequency of presence of third molar teeth and their distribution in each jaw and each side, according to sex, in a group of orthodontic patients with permanent dentition from northern Greece. Methods The sample included panoramic radiographs from 220 patients with permanent dentition (mean age 13.62 ± 1.81). The ?2 test was used to assess the relationships between the variables, and the Fisher’s exact test was used in cases where the expected frequencies in each cell were <5. Results The frequency of third molar presence was 79.1%, and 20.9% was the frequency of third molar agenesis. Intersexual differences in the number of third molars was not statistically significant. There was a correlation between the distribution of third molars on the right and the left side (Fisher’s exact test = 100.788; P = 0). The two sides showed the same tendency toward the presence or absence of third molars. A correlation was also found between the distribution of maxillary and mandibular third molars (Fisher’s exact test = 24.372; P = 0). In each jaw, the presence or absence of third molars was highly related to the number of third molars found in the other jaw. Conclusion The present results showed that in this orthodontic group of northern Greek patients, presence accounted for 79.1% and agenesis for 20.9%. No significant difference was found between the frequencies of third molar presence on the left and right sides in either the maxilla or mandible. PMID:22701086

Barka, Georgia; Tretiakov, Georgios; Theodosiou, Theodosios; Ioannidou-Marathiotou, Ioulia

2012-01-01

149

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

PubMed Central

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 ?m. 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

2014-01-01

150

High-rate partial nitritation using porous poly(vinyl alcohol) sponge.  

PubMed

Poly(vinyl alcohol) (PVA) has been utilized as a support material for the immobilization of nitrifying bacteria without the comprehensive survey of partial nitritation. In the present study, the activities of nitrifiers and the maximum nitrogen conversion rate of partial nitritation with PVA sponge-cubes were specified according to different conditions. The selective enrichment of ammonia-oxidizing bacteria (AOB) on PVA sponge-cubes was achieved by the competition between AOB and nitrite-oxidizing bacteria for dissolved oxygen. The efficiency of ammonia oxidation was proportional to the concentration of HCO3 (-) with the molar ratio of HCO3 (-)-C/NH4 (+)-N = 1.91 and a half of the ratio was applied to the further experiments to ensure stable partial nitritation. The maximum nitrogen conversion rate of partial nitritation was dependent on the volume, not the size of sponge-cubes. The partial nitritation showed the superior rate performance of 3.09 kg N/m(3) day with the packing ratio of 32 % of 5 × 5 × 5 mm(3) PVA sponge-cubes. PMID:24297159

Bae, Hyokwan; Yang, Heejeong; Chung, Yun-Chul; Yoo, Young Je; Lee, Seockheon

2014-06-01

151

Molar heat capacity and entropy of calcium metal  

USGS Publications Warehouse

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.

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

1997-01-01

152

Revascularization/Regeneration performed in immature molars: case reports.  

PubMed

These 3 case reports the outcome of revascularization treatment in necrotic immature molars. During treatment, a tri antibiotic mix was used to disinfect the pulp for 2 weeks. Then a blood clot was created in the canal, over which mineral trioxide aggregate was placed. After 24 months, the immature molars showed continuation of root development. The patients were asymptomatic, no sinus tracts were evident and apical periodontitis was resolved Results from these cases show that revascularization/regeneration using 3Mix-MP method could be effective for managing immature permanent molar teeth with pulpal necrosis. PMID:23855165

Sönmez, I S; Akbay Oba, A; Erkmen Almaz, M

2013-01-01

153

Orthodontic space closure after first molar extraction without skeletal anchorage  

Microsoft Academic Search

Objective  The aim of the study was an analysis of effects and side-effects during mesialization of second molars after extraction of\\u000a the first permanent molars using the anterior dentition\\/premolars (PM) as an anchorage unit.\\u000a \\u000a \\u000a \\u000a \\u000a Patients and methods  A total of 35 patients were examined retrospectively who had undergone unilateral or bilateral first permanent molar extraction\\u000a in the upper or lower arch due

Collin Jacobs; Claudia Jacobs-Müller; Carolin Luley; Christina Erbe; Heiner Wehrbein

2011-01-01

154

Functional Patterns of Molar Occlusion in Platyrrhine Primates  

E-print Network

mechanics . Dentition Molars . Occlusion Tooth wear Platyrrhine. ABSTRACT Mechanico-functional features the particular kinds of insects fed upon by the different genera and the de- tailed characters of the dentition

Rosenberger, Alfred H.

155

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

PubMed Central

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 in the mesiobuccal root among the three roots of the investigated first molar teeth. PMID:23585866

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

2013-01-01

156

Finite Element Reconstruction of a Mandibular First Molar  

PubMed Central

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

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

2013-01-01

157

Bonded molar tubes: a retrospective evaluation of clinical performance.  

PubMed

This study investigated time to first failure of stainless steel orthodontic first permanent molar tubes (Ormco Corp) bonded with a light-cured resin adhesive (Transbond) and assessed whether this was related to patient gender, age of the patient at the start of treatment, the presenting malocclusion, or the operator. All first molar tubes were bonded to intact buccal enamel, free of any restoration. Survival analysis was carried out on data from 483 patients with 1190 bonded first molar tubes. For each case, a single molar tube, either that which was first to fail or had the shortest follow-up time, was chosen for analysis. The median time until first bonded tube failure was 699 days with an overall failure rate of 21% recorded. There was no significant difference in time to first failure of molar tubes with respect to patient gender or presenting malocclusion but significant differences were recorded with respect to the patients' age at the start of treatment and the operator. Age at the start of treatment and operator were identified as independently useful predictors of bonded molar tube survival. PMID:10358250

Millett, D T; Hallgren, A; Fornell, A C; Robertson, M

1999-06-01

158

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)

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.

Head, D. A.

2006-10-01

159

Genetic integration of molar cusp size variation in baboons  

PubMed Central

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

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

2010-01-01

160

Mandibular first molar with six root canals: a rare entity.  

PubMed

Recently, there has been an ongoing trend of case reports that highlight the presence of more than four root canals in mandibular first molars. This tendency warns clinicians to be more prudent when dealing with mandibular first molars requiring endodontic treatment. Moreover, radiographic examination should be taken as a clue providing tool rather than as an absolute guide to anatomy and its associated aberrances. This case reports the successful non-surgical endodontic management of a mandibular first molar with six root canal systems with three canals in the mesial root and three in the distal root. The classification of root canal systems found in this case was Sert and Bayirli type XV in both the roots. After non-surgical endodontic treatment, the tooth was restored definitively with a resin composite core followed by porcelain fused to the metal crown. This case adds to the library of previously reported cases of mandibular first molars with six root canals and further emphasises on the importance of rare morphological deviations that may occur in the mandibular first molars. PMID:25082869

Hasan, Muhammad; Rahman, Munawar; Saad, Najeeb

2014-01-01

161

Western Saudi adolescent age estimation utilising third molar development  

PubMed Central

Objective: The aim of this study was to establish reference data on third molar morphology/development for age estimation in Western Saudi adolescents, between ages 14 and 23 years of old. Materials and Methods: The orthopantomograms of 130 individuals (males and females), were examined, and the stage of third molar development were evaluated. Results: Mean ages, standard deviations, and percentile distributions are presented for each stage of development. The mean estimated age for all participants (n = 130) was 219.7 months, and this differed significantly (P < 0.05) from the mean chronological age (226.5 months). Deviations of predicted age from real age showed 28.5% of all participants had their age estimated within 1 year (±12 months) of their chronological age. Most (43%) had their age underestimated by more than 12 months and the remaining 28.5% had their age overestimated by more than 12 months of their chronological age. Differences in left-right symmetry information of third molars were detected and were higher in the maxilla (92%) than in the mandible (82%). For all molars reaching stage “H” most individuals (males and females) were over the age 18 years of old. Males reach the developmental stages earlier than females. Conclusion: Third molar tooth development can be reliably used to generate mean age and the estimated age range for an individual of unknown chronological age. Further studies with large populations are needed for better statistical results. PMID:25202206

Alshihri, Amin M.; Kruger, Estie; Tennant, Marc

2014-01-01

162

A 3-dimensional analysis of molar movement during headgear treatment.  

PubMed

Superimposition of serial cephalograms provides a limited description of tooth movement that could be complemented by data obtained from serial dental casts. The aim of this study was to develop a mathematical method for superimposing 3-dimensional data obtained from selected landmarks on longitudinally collected dental casts to describe maxillary first molar movement during headgear treatment. The material consisted of dental casts taken bimonthly from 36 children whose Class II Division 1 malocclusion was treated with straight-pull headgear during a 24-month period. Control data were collected from initial and final models of 38 subjects with a similar malocclusion who were not treated during a 24-month observation period. Spatial data from each subject's initial model were oriented similarly in an anatomically derived coordinate system, and a best-fit superimposition of palatal rugae landmarks from subsequent models allowed the measurement of molar movement. On average, headgear treatment resulted in distal movement of the molars, and the fitted net difference between treated and control subjects was 3.00 mm (SE, 0.37 mm; P < .001). Also, the headgear caused significantly more molar extrusion (0.56 mm; SE, 0.20 mm; P < .006) and buccal expansion (0.58 mm; SE, 0.17 mm; P < .001) on average than in the control group. Poor reliability of the method for measuring molar rotations indicated that they could not be determined accurately. Longitudinal description of molar movement for each subject revealed great individual variability in the amount and pattern of tooth movement. Several reasons could account for the wide range of individual variation and warrant exploration. PMID:11786867

Ashmore, Jennifer L; Kurland, Brenda F; King, Gregory J; Wheeler, Timothy T; Ghafari, Joseph; Ramsay, Douglas S

2002-01-01

163

Endodontic Management of a Maxillary Molar with Three Mesiobuccal Canals  

PubMed Central

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

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

2014-01-01

164

Treatment of Ectopic Mandibular Second Permanent Molar with Elastic Separators  

PubMed Central

Ectopic eruption is a developmental disturbance in which the tooth fails to follow its normal eruption pathway. Ectopic eruption of the second molar is relatively rare. This paper presents the case of thirteen-year-old male with an ectopic mandibular second permanent molar. The condition was corrected with surgical exposure and placement of elastic separators. This case report lays emphasis on the practice of basic methods to obtain acceptable results rather than extensive surgical or orthodontic corrections. It is advised that ectopic teeth should not be neglected especially when it concerns developing caries and malocclusion. PMID:25050182

Rajesh, R.; Naveen, V.; Amit, S.; Baroudi, Kusai; Sampath Reddy, C.; Namineni, Srinivas

2014-01-01

165

Procedures to recover DNA from pre-molar and molar teeth of decomposed cadavers with different post-mortem intervals.  

PubMed

A task-force to resolve 26 pending forensic caseworks was carried out. We tested four different protocols to extract DNA from molar and pre-molar teeth from 26 cadavers with post-mortem intervals from 2 months to 12 years. We compared the amount of DNA and DNA profiles with the time elapsed between death and laboratory procedures. Molar or pre-molar teeth were removed from the corpses, cleaned, and DNA was extracted using 2 or 12h of incubation on lysis buffer and filtered using concentration column or precipitated with isopropanol. DNA profiles were obtained using PowerPlex16™ System PCR Amplification Kit, AmpFlSTR(®) Yfiler™ and/or mtDNA sequencing. Complete DNA profiles comparison and statistical evaluation allowed unambiguous identification of the 26 victims. No significant differences were observed in the amount of DNA obtained with the distinct incubation times. The use of concentration column resulted in an increased amount of DNA when compared to isopropanol. However, the lower concentration of DNA obtained with isopropanol seemed to have been compensated by the higher purity. No significant differences in the number of amplified loci were found. A non-significant tendency was found between the amount of total DNA recovered and the time elapsed between death and laboratory procedures. The increase of post-mortem time did not interfere in the analysed autosomal loci. In conclusion, molar and pre-molar teeth were shown to be good candidates to obtain satisfactory DNA profiles, suggesting the high potential of tooth samples as source for DNA typing independently of the decomposed corpse's time or laboratory procedures. PMID:23040740

Raimann, Paulo E; Picanço, Juliane B; Silva, Deborah S B S; Albuquerque, Trícia C K; Paludo, Francis Jackson O; Alho, Clarice S

2012-11-01

166

Management of Six Root Canals in Mandibular First Molar  

PubMed Central

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.

Gomes, Fabio de Almeida; Sousa, Bruno Carvalho

2015-01-01

167

DNA Templated Synthesis (DTS) -Nature's effective molarity based approach-  

E-print Network

Translation DNA RNA Protein Replication mRNA tRNA Nucleic acid templated synthesis plays a important roleDNA Templated Synthesis (DTS) -Nature's effective molarity based approach- Organic Seminar 27th May of many reactants in one solution macromolecule- templated synthesis selective product formation one

Katsumoto, Shingo

168

Variations in the mechanical properties of Alouatta palliata molar enamel.  

PubMed

Teeth have provided insights into many topics including primate diet, paleobiology, and evolution, due to the fact that they are largely composed of inorganic materials and may remain intact long after an animal is deceased. Previous studies have reported that the mechanical properties, chemistry, and microstructure of human enamel vary with location. This study uses nanoindentation to map out the mechanical properties of Alouatta palliata molar enamel on an axial cross-section of an unworn permanent third molar, a worn permanent first molar, and a worn deciduous first molar. Variations were then correlated with changes in microstructure and chemistry using scanning electron microscopy and electron microprobe techniques. The hardness and Young's modulus varied with location throughout the cross-sections from the occlusal surface to the dentin-enamel junction (DEJ), from the buccal to lingual sides, and also from one tooth to another. These changes in mechanical properties correlated with changes in the organic content of the tooth, which was shown to increase from approximately 6% near the occlusal surface to approximately 20% just before the DEJ. Compared to human enamel, the Alouatta enamel showed similar microstructures, chemical constituents, and magnitudes of mechanical properties, but showed less variation in hardness and Young's modulus, despite the very different diet of this species. PMID:19672851

Darnell, Laura A; Teaford, Mark F; Livi, Kenneth J T; Weihs, Timothy P

2010-01-01

169

Experience versus complication rate in third molar surgery  

Microsoft Academic Search

OBJECTIVES: The records of 1087 patients who underwent surgical removal of third molar teeth were prospectively examined to analyse the possible relationship between postoperative complications and the surgeon's experience parameter. METHOD AND MATERIALS: Seven surgeons (three specialists in surgical dentistry [specialists SD] and four oral and maxillofacial Senior House Officers [OMFS residents]) carried out the surgical procedures. For each patient,

Waseem Jerjes; Mohammed El-Maaytah; Brian Swinson; Bilquis Banu; Tahwinder Upile; Sapna D'Sa; Mohammed Al-Khawalde; Boussad Chaib; Colin Hopper

2006-01-01

170

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

PubMed

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. PMID:23618306

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

2013-06-01

171

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

NASA Astrophysics Data System (ADS)

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.

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

2010-06-01

172

A influência do terceiro molar no apinhamento ântero-inferior The influence of the third molar on lower anterior crowding  

Microsoft Academic Search

The aim of the present study was to assess the influence of the third molar on lower anterior crowding, as well as to recommend the best clinical management for dental practitioners to solve this problem. The eruption, impaction, agenesis and prophylactic removal of lower crowding were evaluated by means of a review of the literature. It was possible to observe

Simone Freitas Sotero; Alexandre de Albuquerque Franco; Paulo Germano de Carvalho; Bezerra Falcão

173

Influence of third molar space on angulation and dental arch crowding.  

PubMed

The influence of the third molars on mandibular incisor crowding has been extensively studied but remains controversial. The purpose of this study was to ascertain whether, in Mongolian subjects, the lower third molar can affect anterior crowding and/or the inclination of teeth in the lower lateral segments. Panoramic radiographs, 45° oblique cephalograms, and dental casts were taken from Mongolian subjects (age range 18.3-24.1 years, mean 21.0 years) exhibiting impaction of all four third molars and an Angle Class I molar relationship. The Ganss ratio was calculated using panoramic radiographs, whereas the gonial angle and angulation of lower canines, premolars and molars were measured using 45° oblique cephalograms. Little's index of irregularity was calculated using dental casts. Significant relationships between the angulation of the third and second molars and between the first molars and second premolars were found. Conversely, there was no significant correlation between the angulation of third molars, first premolars and canines. The Ganss ratio calculations showed that the lower first and second molars and the second premolars inclined mesially if there was insufficient space for the lower third molars. However, there was no significant correlation between Little's index of irregularity and third molar angulation. Furthermore, although the third molar influences the lateral segments, no obvious relationship between the third molar and anterior crowding was observed. Therefore, the angulation of the third molar appears not to cause anterior crowding. PMID:22527908

Hasegawa, Yuh; Terada, Kazuto; Kageyama, Ikuo; Tsuchimochi, Takashi; Ishikawa, Fujiro; Nakahara, Sen

2013-01-01

174

A new mammal skull from the Lower Cretaceous of China with implications for the evolution of obtuse-angled molars and ‘amphilestid’ eutriconodonts  

PubMed Central

We report the discovery of Juchilestes liaoningensis, a new genus and species of eutriconodont mammal from the Lujiatun Site of the Lower Cretaceous Yixian Formation (123.2 ± 1.0 Ma; Lower Aptian). The holotype preserves a partial skull and full dentition. Among eutriconodonts, its lower dentition is similar to taxa formerly assigned to the paraphyletic group of ‘amphilestids’. Some have considered ‘amphilestid’ molars to represent the structural intermediate between the lower molars of the ‘triconodont’ pattern of cusps in alignment and the fully triangulate and more derived therian molars. However, ‘amphilestid’ taxa were previously represented only by the lower dentition. Our study reveals, for the first time, the upper dentition and skull structure of an ‘amphilestid’, and shows that at least some eutriconodonts have an obtuse-angled cusp pattern on molars in middle positions of the long molar series. Its petrosal is similar to those of other eutriconodonts and spalacotheroid ‘symmetrodonts’. Our phylogenetic analyses suggest that (i) Juchilestes is most closely related to the Early Cretaceous Hakusanodon from Japan, in the same Eastern Asiatic geographic region; (ii) ‘amphilestids’ are not monophyletic; and (iii) eutriconodonts might not be a monophyletic group, although this hypothesis must be further tested. PMID:19726475

Gao, Chun-Ling; Wilson, Gregory P.; Luo, Zhe-Xi; Maga, A. Murat; Meng, Qingjin; Wang, Xuri

2010-01-01

175

Use of kilovoltage X-ray volume imaging in patient dose calculation for head-and-neck and partial brain radiation therapy  

PubMed Central

Background To evaluate the accuracy of using kilovoltage x-ray cone-beam computed tomography (kV-CBCT) imaging for in vivo dose calculations. Methods A Region-of-Interest (ROI) CT number mapping method was developed to generate the cone-beam CT number vs. relative electron density calibration curve for 3D dose calculations. The stability of the results was validated for three consecutive months. The method was evaluated on three brain tumors and three head-and-neck tumor cases. For each patient, kV-CBCT images were acquired on the first treatment day and two-week intervals on the Elekta XVI system. The delivered dose distributions were calculated by applying the patients' treatment plans to the kV-CBCT images. The resulting dose distributions and dose volume histograms (DVHs) of the tumor and critical structures were compared to the original treatment plan. Results The kV-CBCT electron density calibration was stable within 1.5% over a three-month period. The DVH and dose distribution comparison based on the planning CT and the initial kV-CBCT showed good agreements for majority of cases. The doses calculated from the planning CT and kV-CBCT were compared on planes perpendicular to the beam axes and passing through the isocenter. Using ? analysis with a criterion of 2 mm/2% and a threshold of 10%, more than 99.5% of the points on the iso-planes exhibited ? <1. For one patient, kV-CBCT images detected 5.8% dose variation in the right parotid due to tumor shrinkage and patient weight loss. Conclusions ROI mapping method is an effective method for the creation of kV-CBCT electron density calibration curves for head-and-neck and brain tumor patients. Dose variations as monitored using kV-CBCT imaging suggest that some patients can benefit from adaptive treatment plan re-optimization. PMID:20403191

2010-01-01

176

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

PubMed

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

Medio, Marie; de la Dure Molla, Muriel

2014-09-01

177

Vapor-phase molar Kerr constant values from solution measurements  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

178

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)

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 95.2% in water phantoms without RBE enhancement (planned BED). About 10% increase in the source output is required to raise BED PTV V100 to 95%. As a conclusion, the composite effect of dose reduction in the target due to heterogeneities and RBE enhancement results in a net effect of 5.3% target BED coverage loss for electronic brachytherapy. Therefore, it is suggested that about 10% increase in the source output may be necessary to achieve sufficient target coverage higher than 95%.

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

2010-09-01

179

Endodontic and post-endodontic management of a fused molar.  

PubMed

Treatment of fused teeth needs special care and attention to the bizarre anatomy. This paper describes root canal treatment of a fused carious tooth presenting with apical periodontitis. It is a rare case of fusion of the mandibular second molar with a paramolar. There is no literature regarding placement of crown over endodontically treated fused teeth. In this case, the fused teeth were endodontically treated and restored by a porcelain fused to metal crown. PMID:23965462

Gupta, Ruchi; Prakash, Vijay; Sharma, Mohit

2013-01-01

180

Evaluation of lidocaine and mepivacaine for inferior third molar surgery  

Microsoft Academic Search

Objective: The aim of this study was to compare 2% lidocaine and 2% mepivacaine with 1:100,000 epinephrine for postoperative pain control. Study design: A group of 35 patients, both genders were recruited, whose had ages ranged from 13 to 27 years-old and had two inferior third molars in similar positions to be extracted. The cartridges were distributed to the patients

Gabriela Granja Porto; Cavalcanti Do; Egito Vasconcelos; Ana Cláudia; Amorim Gomes; Daniela Albert

181

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

PubMed Central

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

Baum, William M

2002-01-01

182

Efficacy of Postoperative Prophylactic Antibiotic Therapy in Third Molar Surgery  

PubMed Central

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

Reddy B, Praveen

2014-01-01

183

Quality of life following third molar removal under conscious sedation  

PubMed Central

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

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

2012-01-01

184

Primate molar crown formation times and life history evolution revisited.  

PubMed

Comparative studies have convincingly demonstrated that the pattern and timing of tooth emergence are highly correlated with life-history variables and brain size. Conversely, a firm relationship between molar formation time and life-history variables has not yet been established. It seems counterintuitive that one aspect of dental development should be correlated with life-history variables, whereas the other should not. In order to shed light on this apparent discrepancy this study analyzed all data on primate molar crown formations available in the published literature in relation to life-history variables, brain size, and female body mass. Crown formation times were found to be particularly highly correlated with both female body mass and brain size. Species that depart from the overall brain/body allometry by being relatively large-bodied, e.g., Gorilla gorilla and later Theropithecus oswaldi, also have shorter molar crown formation times than expected. The reverse is not found for species that depart from the overall brain/body allometry due to their larger brains, i.e., Homo sapiens. This finding is interpreted within an evolutionary and ecological framework. Specifically, by focusing on ecological commonalities, a scenario is proposed which may allow predictions to be made about the evolutionary history of other extinct primates also. If confirmed in future studies, crown formation time may again become a powerful tool in evolutionary enquiry. PMID:11748692

Macho, G A

2001-12-01

185

Extra-Oral Approach for Removal of Ectopic Impacted Lower Third Molar: A Case Report  

PubMed Central

Extra oral approach for removal of the lower third molar is uncommon. This case report illustrates an example of removal of lower third molar by extra-oral approach preserving the inferior dental nerve. PMID:25584338

Vishnu, Priya; Kannadasan, Kamal; Kengagsubbiah, Srivatsa; Kumar, Senthil

2014-01-01

186

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

NASA Astrophysics Data System (ADS)

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.

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

2008-08-01

187

Three-dimensional evaluation of the mandibular third molars’ development in unilateral crossbite patients: A cone beam computed tomography study  

PubMed Central

Objectives: The aim was to investigate mandibular third molar (3M)'s maturation in the crossbite and normal sides by two- and three-dimensional analyses using cone beam computed tomography (CBCT). Materials and Methods: A retrospective study was performed using CBCT of 25 patients (16 females and 9 males; mean age: 16.8 ± 2.9 years) with unilateral posterior crossbite. The formation stages and the volume of the mandibular 3Ms were evaluated by means of CBCT data of the patients without knowing the crossbite side of the patients. Results: Statistically no significant differences were found in the development of the 3Ms between the crossbite and the control sides, whereas the volume of 3M was found to be less in the crossbite side than in the normal side (P = 0.021). Conclusions: A volume of 3M was found to be less in the crossbite side than in the normal side. PMID:25202221

Halicioglu, Koray; Celikoglu, Mevlut; Buyuk, Suleyman Kutalmis; Sekerci, Ahmet Ercan; Ucar, Faruk Izzet; Yavuz, Ibrahim

2014-01-01

188

[Partial algodystrophy].  

PubMed

Two patients are described with parcellar algodystrophy, a special form of algodystrophy. Bone biopsy in one patient revealed increased bone resorption and irregular new bone formation. Parcellar algodystrophy is characterized by the very localized pathological changes in the region of a joint. Only a small area of demineralization may be visible on X-ray. Skeletal scintigraphy shows hyperfixation of technetium-99m already in an early stage. Although the inflammatory signs are clinically impressive, the ESR may be normal. History may reveal previous involved joints. Parcellar algodystrophy normally runs a benign course. The difficulty of correct diagnosis is discussed. The changes are compared to those of partial algodystrophy and algodystrophy with no radiological abnormality throughout the course of the disease. PMID:2432654

Diethelm, U; Schlumpf, U; Musy, J P

1986-11-29

189

Surgical extraction of mandibular third molar in pterygomandibular space: a case report.  

PubMed

Impacted mandibular third molars are located between the second mandibular molar and mandibular ramus. However, ectopic mandibular third molars with heterotopic positions are reported in the subcondylar or pterygomandibular space. The usual cause of malposition is a cyst or tumor, and malposition without a pathology is rare. This case report described an impacted mandibular third molar in the pterygomandibular space without any associated pathology. PMID:24471052

Lee, Young-Kyu; Park, Sung-Soo; Myoung, Hoon

2013-10-01

190

Molar uprighting by a nickel-titanium spring based on a setup model.  

PubMed

Molar uprighting is an important adjunctive treatment in orthodontics: repositioning the tilted molar eliminates the potentially pathologic condition and simplifies the ultimate restorative procedure. Although various methods for molar uprighting have been applied successfully, they still have some limitations and disadvantages in tooth movement. This article reports on a new clinical technique for molar uprighting with nickel-titanium springs based on a setup model. Two patients treated with this system are shown. PMID:24975006

Kim, MoonHee; Kim, Minji; Chun, Youn-Sic

2014-07-01

191

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

192

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

PubMed Central

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

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

2012-01-01

193

Restoration of Endodontically Treated Molars Using All Ceramic Endocrowns  

PubMed Central

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

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

2013-01-01

194

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

PubMed Central

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

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

2013-01-01

195

An Odor Interaction Model of Binary Odorant Mixtures by a Partial Differential Equation Method  

PubMed Central

A novel odor interaction model was proposed for binary mixtures of benzene and substituted benzenes by a partial differential equation (PDE) method. Based on the measurement method (tangent-intercept method) of partial molar volume, original parameters of corresponding formulas were reasonably displaced by perceptual measures. By these substitutions, it was possible to relate a mixture's odor intensity to the individual odorant's relative odor activity value (OAV). Several binary mixtures of benzene and substituted benzenes were respectively tested to establish the PDE models. The obtained results showed that the PDE model provided an easily interpretable method relating individual components to their joint odor intensity. Besides, both predictive performance and feasibility of the PDE model were proved well through a series of odor intensity matching tests. If combining the PDE model with portable gas detectors or on-line monitoring systems, olfactory evaluation of odor intensity will be achieved by instruments instead of odor assessors. Many disadvantages (e.g., expense on a fixed number of odor assessors) also will be successfully avoided. Thus, the PDE model is predicted to be helpful to the monitoring and management of odor pollutions. PMID:25010698

Yan, Luchun; Liu, Jiemin; Wang, Guihua; Wu, Chuandong

2014-01-01

196

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

197

Lattice potential energy and standard molar enthalpy in the formation of 1—dodecylamine hydrobromide (1-C12H25NH3·Br)(s)  

NASA Astrophysics Data System (ADS)

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 ?cUmo(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 ?cHmo(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 ?fHmo(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.

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

2011-02-01

198

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

PubMed Central

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

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

2014-01-01

199

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

ERIC Educational Resources Information Center

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)

Pauling, Linus; Herman, Zelek S.

1985-01-01

200

[The pendulis appliance: a palatal miniscrew supported molar distalization device].  

PubMed

The maxillary molar distalization is a valuable therapeutic option in some clinical cases. Its biomechanics is challenging and difficult to obtain. Historically, various devices have been described offering successful solutions to this problem such as the Hilgers Pendulum Appliance (1992) and variants linked to mini screws which recently have shown interesting clinical potential. This article presents a new Pendulum variant using a miniscrew, the "pendulis". It follows the original concept (titanium-molybdenum alloy distalization springs and polymethyl-methacrylate pellet) but dental support is replaced by a single palatal miniscrew (median adults, para-median in children) to which the device is fixed by means of a metal welded cap easily positioned and removable by the practitioner. This allows for better control of the oral hygiene and completely controlled extraoral activation. Fabrication steps are described and instruction of use is illustrated with clinical documentation. PMID:25158749

Nappée-Miévilly, Magali; Nappée, François-Joseph; Kerbrat, Jean-Baptiste; Goudot, Patrick

2014-09-01

201

Molar extinction coefficients of solutions of some organic compounds  

NASA Astrophysics Data System (ADS)

Molar extinction coefficients of aqueous solutions of some organic compounds, viz. formamide (CH_{3}NO), N-methylformamide (C_{2}H_{5}NO), NN-dimethylformamide (C_{3}H_{7}NO), NN-dimethylacetamide (C_{4}H_{9}NO), 1,4-dioxane (C_{4}H_{8}O_{2}), succinimide (C_{4}H_{5}NO_{2}) and solutions of acetamide (C_{2}H_{5}NO) and benzoic acid (C_{7}H_{6}O_{2}) in 1,4-dioxane (C_{4}H_{8}O_{2}) have been determined by narrow beam gamma-ray transmission method at 81, 356, 511, 662, 1173 and 1332 keV. The experimental values of mass attenuation coefficients of these compounds have been used to calculate effective atomic numbers and electron densities. The additivity rule earlier used for aqueous solution has been extended to non-aqueous (1,4-dioxane) solutions.

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

2004-05-01

202

Mandibular molar rehabilitation using orthodontic extrusion associated with odontoplasty.  

PubMed

The aim of this clinical report is to describe the successful treatment of a mandibular first molar presenting an extensive fracture at the buccal aspect in a young patient. The extension of the fracture was a negative prognostic factor for tooth maintenance. An alternative clinical treatment was proposed since the patient was young and presented with good oral hygiene and periodontal health. The treatment was based on orthodontic forced eruption associated with odontoplasty. A 3-year follow-up after the surgical procedure demonstrated the maintenance of periodontal health and good plaque control. It can be concluded that orthodontic forced eruption associated with odontoplasty promoted favorable conditions for prosthetic rehabilitation and is a feasible procedure in the treatment of tooth fracture extended below the cementoenamel junction. PMID:22672712

Cesar-Neto, João Batista; Martos, Josué; Artifon, Luciano; Silveira, Luiz Fernando Machado; Michelon, Douver; Masotti, Alexandre Severo; Silva, José Carlos Maciel

2012-12-01

203

Four impacted fourth molars in a young patient: a case report  

PubMed Central

Summary The occurrence of supernumerary teeth is a relatively uncommon dental anomaly and it’s rare for patients to have impacted fourth molars in all quadrant. Aim of this work is to describe the presence of bilateral fourth molars in the maxilla and the mandible in a young male patient aged 22 years came to our hospital with acute pericoronal infection around unerupted third inferior molars. Routine radiographic examination revealed impacted inferior third molars but also unerupted bilateral upper and inferior fourth molars. The acute infection was treated by local measures and the patient was subsequently admitted for removal of third and fourth impacted upper and lower molars under general anesthesia. PMID:23741604

CLEMENTINI, M.; OTTRIA, L.; PANDOLFI, C.; AGRESTINI, C.; BARLATTANI, A.

2013-01-01

204

Micro-computed tomography analysis of changes in the periodontal ligament and alveolar bone proper induced by occlusal hypofunction of rat molars  

PubMed Central

Objective To three-dimensionally elucidate the effects of occlusal hypofunction on the periodontal ligament and alveolar bone proper of rat molars by micro-computed tomography (micro-CT). Methods Occlusal function in the molar area was restricted by attaching an anterior bite plate on the maxillary incisors and a metal cap on the mandibular incisors of 5-week-old male Wistar rats for 1 week. The periodontal ligament space and alveolar bone proper around roots of the mandibular first molar were assessed by histology and micro-CT. Results The periodontal ligament space was narrower and the alveolar bone proper was sparser and less continuous in the hypofunction group than in the control group. Further, both the volume of the periodontal ligament and the volumetric ratio of the alveolar bone proper to the total tissue in the region of interest were significantly lower in the hypofunction group (p < 0.05). Conclusions Occlusal hypofunction induces atrophic changes in the periodontal ligament and alveolar bone proper of rat molars. PMID:25309866

Hosomichi, Jun; Nakamura, Saeko; Ono, Takashi

2014-01-01

205

Management of mandibular first molar with four canals in mesial root  

PubMed Central

Successful root canal treatment depends on adequate cleaning, shaping, and filling of the root canal system. The presence of middle mesial (MM) root canal of mandibular molars has been reported by various authors. But incidence of four canals in mesial root of mandibular molar is very rare. The aim of this case report is to present and describe the identification and management of a mandibular first molar with four canals in the mesial root and single canal in the distal root. PMID:24082581

Subbiya, Arunajatesan; Kumar, Krishnamurthy Sathish; Vivekanandhan, Paramasivam; Prakash, Venkatachalam

2013-01-01

206

A Maxillary Second Molar with Two Separate Palatal Roots: A Case Report  

PubMed Central

Variations of dental root canals were reported by different authors. One of the rare variations is the presence of two separate palatal roots of maxillary molars, especially second maxillary molars. This case study reported a maxillary second molar with two separate palatal roots and a palatal bifurcation which was found during the periodontal flap surgery. Although these variations are rare, awareness of their presence would help in successful periodontal and endodontic treatment. PMID:24724127

Fakhari, E; Shokraneh, A

2013-01-01

207

UPPER VS. LOWER MOLARS FOR CEMENTUM ANNULI AGE DETERMINATION OF DEER  

Microsoft Academic Search

Ages were determined for 23 black-tailed deer (Odocoileus hemionus columbianus) and 14 white-tailed deer (0. virginianus) by examination of cementum annuli of both upper and lower 1st molars. Although estimated ages were virtually the same for both upper and lower molars, the clarity of annuli was significantly greater in upper molars for both species. Abstract: Ages were determined for 23

DALE R. McCULLOUGH; PAUL BEIER

208

Representations of partial derivatives in thermodynamics  

NSDL National Science Digital Library

One of the mathematical objects that students become familiar with in thermodynamics, often for the first time, is the partial derivative of a multivariable function. The symbolic representation of a partial derivative and related quantities present difficulties for students in both mathematical and physical contexts, most notably what it means to keep one or more variables fixed while taking the derivative with respect to a different variable. Material properties are themselves written as partial derivatives of various state functions (e.g., compressibility is a partial derivative of volume with respect to pressure). Research in courses at the University of Maine and Oregon State University yields findings related to the many ways that partial derivatives can be represented and interpreted in thermodynamics. Research has informed curricular development that elicits many of the difficulties using different representations (e.g., geometric) and different contexts (e.g., connecting partial derivatives to specific experiments).

Thompson, John R.; Manogue, Corinne A.; Roundy, David J.; Mountcastle, Donald B.

2012-05-15

209

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

NASA Technical Reports Server (NTRS)

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.

Fedors, R. F.

1974-01-01

210

[Stress analysis of distal free-end removable partial denture].  

PubMed

The study of the force distribution in distal free-end removable partial denture is complicated by the great difference of biomechanical property between the supporting tissue of the distal free-end removable partial denture, abutment tooth and alveolar mucosa under the denture base. Finite element method (FEM) was used in this study to estimate the effect on the abutment tooth and alveolar mucosa under various load conditions. The model is composed of the second premolar, the first molar and the second molar in acrylic resin teeth with the first premolar serving as the abutment. The stress on the abutment tooth was found reduced by 15% on comparing the load condition 3 (222 newton vertical force on each denture acrylic tooth) with the load condition 2 (222 newton vertical force on the second premolar and the first molar), and it can be further reduced by 22% in comparison to load condition 4 (222 newton vertical force on each denture tooth but shared equally to two occlusal contact points per denture tooth). The maximum displacement of the alveolar mucosa was found adjacent to the load area, and the maximum vertical displacement of the alveolar mucosa at load condition 4 is only 0.015 mm greater than load condition 3. It is concluded that when the number of occlusal contacts in distal free-end removable partial denture is increased and evenly distributed, the load on the abutment tooth will be decreased, with only minor effect on the alveolar mucosa. PMID:2282568

Liau, Y S; Chen, P S

1990-12-01

211

Molar crown inner structural organization in Javanese Homo erectus.  

PubMed

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. Am J Phys Anthropol 156:148-157, 2015 © 2014 Wiley Periodicals, Inc. PMID:25209431

Zanolli, Clément

2015-01-01

212

The third molar controversy: Framing the controversy as a public health policy issue  

Microsoft Academic Search

Purpose: This article summarizes the current research available concerning the removal of impacted third molars, and provides a background from which practitioners, public health policy advocates, and third-party payers can more objectively assess the the issues of appropriateness of care and overutilization of third molar surgery.Materials and Methods: A literature review was undertaken, with emphasis on noninterventional outcome studies and

William G Flick

1999-01-01

213

The transfer of occlusal forces through the maxillary molars: A finite element study  

Microsoft Academic Search

The morphology of the skeleton is known to reflect functional demand. A change in the intramaxillary position of molars can be expected to influence the transfer of occlusal forces to the facial skeleton. A finite element analysis allows us to simulate the displacement of a molar in relation to the well-defined morphology of the maxilla. Three 3-dimensional unilateral models of

Paolo M. Cattaneo; Michel Dalstra; Birte Melsen

2003-01-01

214

Radiographic Survey of Third Molar Development in Relation to Chronological Age Among Japanese Juveniles  

Microsoft Academic Search

The aim of the present study was to establish Japanese reference material on the third molar development of Japanese juveniles for forensic application. Observations were performed on the orthopantomograms of 1282 Japanese patients between the ages of 14.0 and 24.0 years. Demirjian formation stages of the maxillary and mandibular third molars were recorded for chronological evaluation of wisdom teeth and

Akita Hondo

215

Brief communication: correcting overestimation when determining two-dimensional occlusal area in human molars.  

PubMed

The robustness index (RI) is determined by multiplying dental mesiodistal and buccolingual diameters, and is used to estimate occlusal area. However, because teeth are not rectangular its calculation consistently causes overestimations. Moreover, teeth, in particular molars, are not identically shaped so overestimations vary. The current study seeks to determine the extent to which overestimations are affected by tooth shape and to improve RI's efficacy. Initially, 120 molars were sorted into six shape groups, which were determined by hypocone/hypoconulid expression. Three maxillary and three mandibular shape groups were set using the Arizona State University Dental Anthropology System. ANOVA results determined that RI overestimations, which averaged around 20%, were not the same for each shape category. Maxillary molars with large hypocones and mandibular molars with no hypoconulids were overestimated significantly less than the other molar groups. Regression-based correction formulae were generated and applied to the original sample. These formulae far more precisely estimated tooth area than RI and there were no differences in estimation based upon tooth shape. A subsequent validation study of 24 additional molars was undertaken to test the formulae on teeth not from the original sample. Overestimation/underestimation averaged 0.5% and was about the same for each of the tooth shape groups. Finally, six new correction formulae were generated using all 144 molars. The correction formulae provide, what is termed here, an adjusted robustness index (ARI), and it is recommended that ARI is used in future studies of molar occlusal area. PMID:21469080

Schmidt, Christopher; Ousley, Stephen; Schmidt, Molly

2011-06-01

216

Tooth anomalies associated with failure of eruption of first and second permanent molars  

Microsoft Academic Search

The occurrence of tooth anomalies in association with failure of the first and second molars to erupt was assessed in a sample of 1520 nonsyndromic subjects with uncrowded dental arches (mean age, 14 years 4 months) and compared with the prevalence rate calculated in a matched control group of 1000 subjects. The tooth anomalies examined included infraocclusion of deciduous molars,

T. Baccetti

2000-01-01

217

VERIFICAÇÃO DOS SINAIS RADIOGRÁFICOS MAIS FREQÜENTES DA RELAÇÃO DO TERCEIRO MOLAR INFERIOR COM O CANAL  

Microsoft Academic Search

The purpose of this study was to evaluate the type and frequency of the radiographic signs of an intimate relationship between the lower third molar and the mandibular canal through the use of panoramic radiography. The sample comprised 31 lower third molars that radiologically presented an intimate relationship with the mandibular canal. For evaluation purposes panoramic radiographs and the classifications

Ana Cláudia; Amorim GOMES; Belmiro Cavalcanti; Egito VASCONCELOS; Emanuel DIAS de Oliveira; Daniela Guimarães de Melo

218

Anatomical and histological features of C-shaped canals in mandibular second molars.  

PubMed

The mandibular second molar has many root canal variations. This investigation used two evaluation methods to examine the canal morphology of mandibular second molars having C-shaped canals. Fifteen extracted mandibular second molars with a conical root and C-shaped canal orifice were separated into two groups. A polyester cast resin technique allowed three-dimensional visualization of the root canal system in eight teeth; the remaining seven molars were prepared for histological examination in cross-section in the coronal, middle, and apical thirds for study under the light microscope. The results illustrated that C-shaped canals in mandibular second molars can vary in number and shape along the length of the root with the result that debridement, obturation, and restoration in this group may be unusually difficult. PMID:1809802

Melton, D C; Krell, K V; Fuller, M W

1991-08-01

219

A fine-structural analysis of mouse molar odontoblast maturation.  

PubMed

The first mandibular molars of the Swiss albino mice, 1 through 4 days of age, were fixed in glutaraldehyde or Karnovsky's fixative. The tissues were postfixed in OSO4, dehydrated and embedded in Epon. The prepolarizing, polarizing and secretory odontoblasts were described. The prepolarizing cells, located in the vicinity of the cervical loop, were mesenchymal-like in morphology. The cells of the polarizing stage possessed organelles indicative of protein synthesis. The nucleus was located proximally. Aperiodic fibers were evident in the wide basement membrane. The secretory odontoblasts were long, slender, polarized cells closely adjoining one another. Each odontoblast possessed six morphologically discernible regions: (1) an infranuclear region, limited in size and containing few cellular organelles; (2) a nuclear region, housing the oval nucleus and a few associated lamellae of rough endoplasmic reticulum as well as a limited number of mitochondria; (3) a supranuclear rough endoplasmic reticulum region, possessing an abundance of these organelles as well as some mitochondria and secretory vesicles; (4) a Golgi region, occupying the middle third of the cell, housing the elements of an extensive Golgi apparatus which was surrounded by peripherally located profiles of rough endoplasmic reticulum; additionally, this region contained smooth endoplasmic reticulum, mitochondria, numerous secretory granules and vesicles and occasional intracellular collagen fibers; (5) an apical rough endoplasmic reticulum region, containing a rough endoplasmic reticulum component that was less extensive than its supranuclear counterpart; in addition, this region was the one richest in mitochondria and contained a plethora of secretory vesicles and granules; (6) the odontoblastic process, a region mostly void of organelles, containing various secretory products, some of which appeared to be in the process of being released extracellularly into the surrounding dentin matrix. PMID:425821

Gartner, L P; Seibel, W; Hiatt, J L; Provenza, D V

1979-01-01

220

Analysis of quantitative trait locus effects on the size and shape of mandibular molars in mice.  

PubMed Central

While >50 genes have been found to influence the development of teeth in mice, we still know very little about the genetic basis for the adaptive characteristics of teeth, such as size and shape. We applied interval mapping procedures to Procrustes size and shape data obtained from 10 morphological landmarks on the mandibular molar row of the F(2) progeny from a cross between the LG/J and SM/J strains of mice. This revealed many more QTL for molar shape (18) than for molar centroid size (3), although levels of dominance effects were comparable among QTL for size and shape. Comparisons of patterns of Procrustes additive and dominance shape effects and ordination of QTL effects by principal components analysis suggested that the effects of the shape QTL were dispersed among the three molars and thus that none of these molars represents a genetically distinct developmental structure. The results of an analysis of co-occurrence of QTL for molar shape, mandible shape, and cranial dimensions in these mice suggested that many of the QTL for molar shape may be the same as those affecting these other sets of characters, although in some cases this could be due to effects of closely linked genes. PMID:11973311

Workman, Michael Scott; Leamy, Larry J; Routman, Eric J; Cheverud, James M

2002-01-01

221

Partial tooth gear bearings  

NASA Technical Reports Server (NTRS)

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.

Vranish, John M. (Inventor)

2010-01-01

222

Name: Seetin Question: In patients with mixed dentition, who have lost a single primary 2nd molar and require space  

E-print Network

Name: Seetin Question: In patients with mixed dentition, who have lost a single primary 2nd molar, comparison, outcome) P: Mixed dentition, lost single primary 2nd molar I: Unilateral space maintainer

Goldman, Steven A.

223

Hypohyperdontia: Agenesis of three third molars and mandibular centrals associated with midline supernumerary tooth in mandible.  

PubMed

Agenesis of teeth in a patient who also presents with a supernumerary tooth is one of the rare numerical anomalies in human dentition. Agenesis of third molars was shown to be associated with other missing permanent teeth. A review of literature on hypodontia including third molar agenesis, hyperdontia and a concomitant presence of these two conditions which is termed as hypohyperdontia is presented along with a case showing agenesis of three third molars, both mandibular central incisors and a midline supernumerary tooth. PMID:22114403

Nuvvula, Sivakumar; Kiranmayi, M; Shilpa, G; Nirmala, S V S G

2010-07-01

224

Molar development in common chimpanzees (Pan troglodytes) T.M. Smith a,*, D.J. Reid b  

E-print Network

Molar development in common chimpanzees (Pan troglodytes) T.M. Smith a,*, D.J. Reid b , M.C. Dean c and cuspal enamel thickness both vary within a cusp type, among cusps, and among molars, resulting in marked, and outer enamel) within and among cusp types and among molar types. Significantly increasing trends

Smith, Tanya M.

225

40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.  

...you use multiple venturis and you calibrated each venturi independently to determine a separate discharge coefficient, C d (or calibration coefficient, K v ), for each venturi, calculate the individual molar flow rates through...

2014-07-01

226

Endodontic management of a maxillary molar with formation supradentalis: A case report  

PubMed Central

Anatomic variations may be observed in the crown or in the roots of maxillary molars. In rare instances, crown and root morphology, both show variations. Occurrence of paramolar cusp on the occlusal surface as central cusp or on the buccal surface as parastyle has been frequently reported in maxillary molars. However, presence of paramolar cusp on the palatal surface has not been reported. ‘Formation supradentalis’ is a condition in which supernumerary cusp is associated with a supernumerary root in a molar. The occurrence of such concomitant corono-radicular morphology is multifactorial, that is primary polygenic with secondary environmental influences. This case reports the diagnosis and endodontic management of Formation-supradentalis that had six cusps and four roots in the maxillary first molar. The tooth exhibited a prominent paramolar palatal cusp and cusp of Carabelli along with a supernumerary palatal root. To the best of author's knowledge, this is the first documentation of endodontic management of Formation supradentalis. PMID:25298653

Shah, Dipali Y.; Jadhav, Ganesh R.

2014-01-01

227

Effects of ozone therapy on pain, swelling, and trismus following third molar surgery.  

PubMed

The aim of this study was to evaluate the efficacy of therapeutic ozone application in the management of pain, swelling, and trismus associated with the surgical removal of impacted mandibular third molars. Sixty consecutive patients with asymptomatic bilateral impacted mandibular third molars were recruited into the study. Randomly, by use of envelops, the molar on one side was extracted and ozone therapy was given (study side); the molar on the other side was extracted 2 weeks later and sham ozone therapy was given (negative control side). The mean age of the 60 patients was 22.6±2.3 years (range 18-25 years). No differences were found between the two sides for mouth opening or swelling. The degree of pain and the number of analgesic tablets taken was significantly lower for the study side. This study showed ozone therapy to have a positive effect on OHIP-14 questionnaire results. PMID:24332588

Kazancioglu, H O; Kurklu, E; Ezirganli, S

2014-05-01

228

Root Canal Morphology of Mandibular First Permanent Molars in an Indian Population  

PubMed Central

An in vitro study was performed to determine the number of roots, root canals per tooth, root canal configurations, and frequency of isthmi and apical deltas in mandibular first permanent molars in an Indian population. Hundred and fifty mandibular first permanent molars were collected and subjected to clearing technique. The cleared teeth were examined in a stereomicroscope under 7.5x magnifications. The canal configurations were categorized using Vertucci's classification. Overall 94.6% of the mandibular first molars had two roots, and 5.3% had extradistal roots (distolingual root). In addition, 64% of the specimens had three root canals, and 36% had four root canals. The most common canal configurations of mesial and distal roots were Vertucci type IV (54%) and type I (65.3%), respectively. Clinician should be aware of the complex root canal morphology of mandibular first molars among the Indian population before and during the root canal treatment. PMID:22287965

Chourasia, Hemant Ramesh; Meshram, Ganesh K.; Warhadpande, Manjusha; Dakshindas, Darshan

2012-01-01

229

Indications for removal of impacted mandibular third molars: a single institutional experience in Libya  

Microsoft Academic Search

Aims  To investigate the various indications for the removal of impacted lower third molars in a dental school in Libya.\\u000a \\u000a \\u000a \\u000a Methods  The records of all patients who underwent a surgical removal of a lower third molar over a 3 year period were reviewed retrospectively.\\u000a The indications for removal were classified into 10 groups. Radiographs were also studied to determine angular position as

B. Krishnan; Mohammad Hossni El Sheikh; El-Gehani Rafa; H. Orafi

2009-01-01

230

Unusual maxillary first molar with 2 palatal canals within a single root: a case report.  

PubMed

A case report is presented regarding a maxillary first molar with 5 canals. The morphology is atypical because it is characterized by a single palatal root with 2 canals with separate orifices joining in the apical third. A literature review pertaining to the morphology of maxillary first molars is discussed. Modifications to the normal access opening and examination of the pulpal floor for additional canals are stressed. PMID:11370279

Johal, S

2001-04-01

231

Evaluation of radius of gyration and intrinsic viscosity molar mass dependence and stiffness of hyaluronan.  

PubMed

Nine hyaluronan (HA) samples were fractionated by size-exclusion chromatography, and molar mass (M), radius of gyration (Rg), and intrinsic viscosity ([eta]) were measured in 0.15 M NaCl at 37 degrees C by on-line multiangle light scattering and viscometer detectors. Using such method, we investigated the Rg and [eta] molar mass dependence for HA over a very wide range of molar masses: M ranging from 4 x 10(4) to 5.5 x 10(6) g/mol. The Rg and the [eta] molar mass dependence found for HA showed a meaningful difference. The Rg = f(M) power law was substantially linear in the whole range of molar masses explored with a constant slope of 0.6. In contrast, the [eta] = f(M) power law (Mark-Houwink-Sakurada plot) showed a marked curve shape, and a linear regression over the whole range of molar masses does not make sense. Also the persistence length (stiffness) for HA was estimated. The persistence length derived by using both the Odijk's model (7.5 nm from Rg vs M data) and the Bohdanecky's plot (6.8 nm from [eta] vs M data) were quite similar. These persistence length values are congruent with a semistiff conformation of HA macromolecules. PMID:14606912

Mendichi, Raniero; Soltés, Ladislav; Giacometti Schieroni, Alberto

2003-01-01

232

An in vitro assessment of type, position and incidence of isthmus in human permanent molars  

PubMed Central

Root canal anatomical complexities, such as isthmus, may limit the action of the endodontic instruments, irrigant solutions and intracanal medications, leading to endodontic treatment failure. Objectives This in vitro study assessed the type, position and incidence of isthmus in human permanent molars. Material and Methods One hundred and twenty eight upper and lower first and second permanent molars were analyzed. The roots were embedded in transparent resin, and then split at different distances from the apex (1.0-2.5-4.0-5.5-7.0 mm). Following the sample examination in stereomicroscope, the data were submitted to chi-square statistical test at a 5% significance level. Results The highest isthmus incidence was at 7.0 mm from the root apex in all samples, except the distal root of lower molars (at 5.5 mm). In upper and lower molars, type V (complete isthmus with a continuous opening between the two main root canals) was the most common classification of isthmus (28.8%). In the mesial root of first and second mandibular molars, type IV had the highest incidence (36% and 23.9%, respectively). Conclusion It was concluded that isthmus was widely found in flat roots, with a low percentage in areas close to the apex. In upper and lower molars, these structures were most frequently found at 7 mm from the apex. PMID:25141198

de LIMA, Fernando José Camello; MONTAGNER, Francisco; JACINTO, Rogério Castilho; AMBROSANO, Glaucia Maria Bovi; GOMES, Brenda Paula Figueiredo de Almeida

2014-01-01

233

Yeast Genomic Library Genomic DNA Sau3AI partial digestion  

E-print Network

Yeast Genomic Library Concept: Genomic DNA ­ Sau3AI partial digestion Vector DNA ­ BamHI full digestion partial Ligate and transform above products Vector Information: · use centromeric plasmid to avoid of the mcs Preparing Vector: 1) digest 3-4ug of library vector with BamHI for 2-4hrs in a total volume of 20

Odorizzi, Greg

234

Determination of intracellular osmotic volume and sodium concentration in dunaliella.  

PubMed

A new method to measure intracellular volume in Dunaliella was developed, where lithium ions are used as monitors of the extracellular volume. Li(+) is shown to be impenetrable to the intracellular volume, insignificantly absorbed to the algae, and is rapidly and evenly distributed within the extracellular volume. The method is suggested to be free of several limitations and consistent errors present in several previously employed techniques.Using the new technique it is shown that both Dunaliella salina and Dunaliella bardawil adjust to a constant cellular volume when grown in a medium containing salt concentrations ranging from 0.5 molar to 4 molar NaCl. That volume is 90 femtoliter per cell for D. salina and 600 femtoliter per cell for D. bardawil. Nonosmotic volume accounts for about 10% of the total cell volume.The intracellular sodium concentration, as determined with the new technique, was under all experimental conditions tested below 100 millimolar. This was true both for cells grown on 0.5 to 4 molar NaCl, and during the osmoregulatory process. It is thus concluded that intracellular NaCl is a minor contributor to the overall intracellular osmotic pressure in Dunaliella. PMID:16664332

Katz, A; Avron, M

1985-08-01

235

Analysis and evaluation of relative positions of mandibular third molar and mandibular canal impacts  

PubMed Central

Objectives This study used cone-beam computed tomography (CBCT) images to categorize the relationships between the mandibular canal and the roots and investigated the prevalence of nerve damage. Materials and Methods Through CBCT images, contact and three-dimensional positional relationships between the roots of the mandibular third molar and the mandibular canal were investigated. With this data, prevalence of nerve damage according to the presence of contact and three-dimensional positional relationships was studied. Other factors that affected the prevalence of nerve damage were also investigated. Results When the mandibular third molar and the mandibular canal were shown to have direct contact in CBCT images, the prevalence of nerve damage was higher than in other cases. Also, in cases where the mandibular canal was horizontally lingual to the mandibular third molar and the mandibular canal was vertically at the cervical level of the mandibular third molar, the prevalence of nerve damage was higher than in opposite cases. The percentage of mandibular canal contact with the roots of the mandibular third molar was higher when the mandibular canal was horizontally lingual to the mandibular third molar. Finally, the prevalence of nerve damage was higher when the diameter of the mandibular canal lumen suddenly decreased at the contact area between the mandibular canal and the roots, as shown in CBCT images. Conclusion The three-dimensional relationship of the mandibular third molar and the mandibular canal can help predict nerve damage and can guide patient expectations of the possibility and extent of nerve damage. PMID:25551092

Kim, Hang-Gul

2014-01-01

236

Caries management strategies for primary molars: 1-yr randomized control trial results.  

PubMed

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

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

2014-11-01

237

Partial Derivative Visualization Gallery  

NSDL National Science Digital Library

This resource is a small gallery of demos for illustrating partial derivatives geometrically. These animations can be used by instructors in a classroom setting or by students to aid in acquiring a visualization background for partial derivatives. Two file formats, gif and QuickTime files are used for the animations which can be downloaded.

Roberts, Lila F.

2004-11-11

238

World-volume action for fractional branes ? ? Work partially supported by the EC RTN programme HPRN-CT-2000-00131 in which G.S. is associated with Frascati-LNF  

Microsoft Academic Search

We study the world-volume action of fractional Dp-branes of type IIA string theory compactified on the orbifold T4\\/Z2. The geometric relation between these branes and wrapped branes is investigated using conformal techniques. In particular we examine in detail various scattering amplitudes and find that the leading low-energy interactions are consistent with the boundary action derived geometrically.

Paolo Merlatti; Gianluca Sabella

2001-01-01

239

Gender Determination Using Diagonal Measurements of Maxillary Molar and Canine Teeth in Davangere Population  

PubMed Central

Background: Mesiodistal and buccolingual measurements of the teeth have been the traditional means of determining gender which sometimes are difficult to measure. Aims and Objectives: To assess the degree of sexual dimorphism in upper permanent canines and first molars using diagonal diameters and to evaluate the applicability of diagonal measurements in sex determination. Materials and Methods: Mesiobuccal-distolingual (MBDL) and distobuccal-mesiolingual (DBML) measurements of the crown and cervix of maxillary canine and maxillary molar were taken using digital vernier callipers in 100 upper dental casts obtained from 50 males and 50 females of the age group of 17-25 y. Results: With step wise discriminant function analysis, results were statistically significant with males showing higher diagonal measurement values. The classification accuracy for males was 69% and in females was 73% with overall accuracy of 71%. Results showed that canines exhibited highest accuracy with cervical measurements being more dimorphic. MBDL measurements were found to be more reliable. Most dimorphicmeasurements included right molar cervical MBDL, left molar cervical MBDL followed by right and left molar crown MBDL. Conclusion: In cases of tooth rotations, crowding, certain fillings and attritions where traditional mesio-distal and bucco-lingual measurements are not applicable, diagonal measurements could be of help in predicting gender.

Tarigoppula, Ratna Kumari V. N.; Kulkarni, Pavan G; BS, Anil

2014-01-01

240

Mandibular cephalometric characteristics of a Saudi sample of patients having impacted third molars  

PubMed Central

Objective To evaluate the cephalometric characteristics of mandibles of Saudi patients having impacted third molars and to compare them to those of patients having normally erupted third molars. Material and methods One hundred and twenty-one Saudi adult subjects (59 females and 62 males; age: 20–40 years) were divided into two groups based on the status of the mandibular third molars: (1) impaction group and (2) normal group. Means and standard deviations of 21 cephalometric measurements related to mandibular geometry were measured and compared between the two groups using the unpaired t-test. Males and females in the impaction group were also compared with their equivalent subgroups in the normal group using the unpaired t-test. Results Anteroposteriorly, space distal to second molar, ramal width and mandibular body length were significantly less in the impaction group than in the control group. In addition, posterior teeth were more upright in the impaction group. Vertically, posterior alveolar height was significantly less in the impaction group. The Y-axis was significantly increased in the impaction group. The significance of these measurements was variable between males and females. Conclusions Third-molar impactions in the Saudis living in the Western region of Saudi Arabia were more likely to occur when inadequate retromolar space is present. This can be attributed to certain mandibular skeletal and dental features, among which the increased width of mandibular ramus and backward inclination of posterior teeth seem to be the most influencing factors in both sexes. PMID:23960502

Hassan, Ali H.

2010-01-01

241

Root and Canal Morphology of Mandibular Third Molars in an Iranian Population  

PubMed Central

Background and aims A through knowledge of the root canal morphology is required for successful endodontic ther-apy. The aim of this study was to investigate the root and canal morphology of mandibular third molars in Kerman, a prov-ince in southeast of Iran. Materials and methods One-hundred-fifty extracted mandibular third molars were collected randomly from different dental clinics in Kerman. The root canal anatomy and morphology of each tooth was carefully studied using a clearing tech-nique. Root number and morphology, number of canals per root, root canal configuration according to Vertucci classifica-tion, and incidence of dilacerated roots and C-shaped canals in mandibular third molars were evaluated under stereomicro-scope with ×2 to ×3 magnifications. Results From the total of 150 mandibular third molars studied, 21% had one root. The majority of teeth (73%) had two roots. 5.5% of the teeth had three roots. The incidence of C-shaped canal was 3.5% in this study and 8% of the teeth had at least one dilacerated root. Conclusion Although root canal anatomy and morphology of mandibular third molars is very variable having two roots seems to be the normal anatomy for these teeth. PMID:22991643

Kuzekanani, Maryam; Haghani, Jahangir; Nosrati, Hossein

2012-01-01

242

Anatomical study of C-shaped canals in mandibular second molars by analysis of computed tomography.  

PubMed

The aim of this study was to investigate the prevalence and configuration of the C-shaped canal using serial axial computed tomography images of the mandibular second molars that had not been restored severely or treated endodontically, and to compare the thickness of the remaining tooth structure from the center of the canal to the outer surface of the deepest groove area in C-shaped mandibular second molar to that of "danger zone of perforation" in normal mandibular second molar. This distance was measured at the cervical, middle, and apical third level each. From 220 teeth, C-shaped canals were found in 98 teeth (44.5%). Almost all the grooves were directed lingual (99%). The continuous C-shaped canal was the most frequently found (49%) and the separated canal was the least (17.4%). The thinnest remaining tooth structure in the groove area of the C-shaped mandibular second molar was not different from that of the danger zone of normal mandibular second molar at the three levels (p > 0.05). PMID:16410060

Jin, Guang-Chun; Lee, Seong-Jong; Roh, Byoung-Duck

2006-01-01

243

Cross-sectional study of correlation between mandibular incisor crowding and third molars in young Brazilians  

PubMed Central

Objectives: The aim of this study was to evaluate transversally the clinical correlation between lower incisor crowding and mandible third molar. Study Design: Three hundred healthy volunteers (134 male and 166 female), aged 20.4 (±2.4) years-old were submitted to a complete clinical examination and filled up a questionnaire about gender, age, total teeth number and presence or absence of superior and inferior third molar. After a recent panoramic radiography were evaluated. The multiple logistic regression showed that none of the studied factors influenced the mandibular incisor crowding. Results: The proportion of both molars present or both absent was higher than the other conditions (Chi-square, p<.0001). The multiple logistic regression showed that any of the studied factors, influenced (p>.05) the mandibular incisor crowding. Despite the statistical significance, wear orthodontics appliances showed a little correlation (odds ratios < 1.0) in the mandibular incisor crowding. Conclusion: Presence of maxillary and/or mandibular third molars has no relation with the lower incisor crowding. Key words:Malocclusion, third molars, lower incisor crowding, mandible. PMID:23385508

Karasawa, Lilian H.; Groppo, Francisco C.; Prado, Felippe B.; Caria, Paulo H F.

2013-01-01

244

Brief communication: possible third molar impactions in the hominid fossil record.  

PubMed

Impacted third molars affect 15%-20% of modern Americans and Western Europeans. In contrast, third molar impactions have not been reported in the early hominid fossil record. It is uncertain whether the lack of reports reflects an absence of impactions or a failure to recognize them. This communication is intended to raise awareness of the possibility of impactions by describing the appearance of impacted teeth and by noting two possible instances of impaction in early hominids. Specifically, the mandibular third molars of the Sterkfontein specimen, STS52b (Australopithecus africanus), and the left maxillary third molar of the Lake Turkana specimen, KNM-WT 17400 (Australopithecus boisei), are positioned in a manner which suggests that they would not have erupted normally. Both specimens also exhibit strong crowding of the anterior dentition, providing further support for the view that these individuals lacked sufficient space for normal eruption of the third molars. Other published reports of dental crowding in the hominid fossil record are noted, and it is suggested that more attention be paid to dental impaction and dental crowding in hominid evolution. PMID:8372939

Gibson, K R; Calcagno, J M

1993-08-01

245

Evc regulates a symmetrical response to Shh signaling in molar development.  

PubMed

Tooth morphogenesis involves patterning through the activity of epithelial signaling centers that, among other molecules, secrete Sonic hedgehog (Shh). While it is known that Shh responding cells need intact primary cilia for signal transduction, the roles of individual cilia components for tooth morphogenesis are poorly understood. The clinical features of individuals with Ellis-van Creveld syndrome include various dental anomalies, and we show here that absence of the cilial protein Evc in mice causes various hypo- and hyperplasia defects during molar development. During first molar development, the response to Shh signaling is progressively lost in Evc-deficient embryos and, unexpectedly, the response consistently disappears in a buccal to lingual direction. The important role of Evc for establishing the buccal-lingual axis of the developing first molar is also supported by a displaced activity of the Wnt pathway in Evc mutants. The observed growth abnormalities eventually manifest in first molar microdontia, disruption of molar segmentation and symmetry, root fusions, and delayed differentiation. Analysis of our data indicates that both spatially and temporally disrupted activities of the Shh pathway are the primary cause for the variable dental anomalies seen in patients with Ellis-van Creveld syndrome or Weyers acrodental dysostosis. PMID:23315474

Nakatomi, M; Hovorakova, M; Gritli-Linde, A; Blair, H J; MacArthur, K; Peterka, M; Lesot, H; Peterkova, R; Ruiz-Perez, V L; Goodship, J A; Peters, H

2013-03-01

246

Partially coherent lensfree tomographic microscopy?  

PubMed Central

Optical sectioning of biological specimens provides detailed volumetric information regarding their internal structure. To provide a complementary approach to existing three-dimensional (3D) microscopy modalities, we have recently demonstrated lensfree optical tomography that offers high-throughput imaging within a compact and simple platform. In this approach, in-line holograms of objects at different angles of partially coherent illumination are recorded using a digital sensor-array, which enables computing pixel super-resolved tomographic images of the specimen. This imaging modality, which forms the focus of this review, offers micrometer-scale 3D resolution over large imaging volumes of, for example, 10–15 mm3, and can be assembled in light weight and compact architectures. Therefore, lensfree optical tomography might be particularly useful for lab-on-a-chip applications as well as for microscopy needs in resource-limited settings. PMID:22193016

Isikman, Serhan O.; Bishara, Waheb; Ozcan, Aydogan

2012-01-01

247

Stress distribution produced by correction of the maxillary second molar in buccal crossbite.  

PubMed

The purpose of this study was to evaluate the stress distribution produced in the dentoalveolar system by a maxillary posterior crossbite appliance used for the correction of maxillary second molars in buccal crossbite. A photoelastic model was fabricated using a photoelastic material (PL-3) to simulate alveolar bone and ivory-colored resin teeth. The model was anteriorly and posteriorly observed with a circular polariscope and photographically recorded before and after activation of the maxillary posterior crossbite appliance. An uncontrolled palatal tipping and a rotating force were generated when the traction force was applied on the palatal surface of the maxillary second molar. A controlled tipping and an intrusive force were generated when the traction force was applied on the buccal surface of the maxillary second molar. PMID:12401047

Yoon, Young-Jooh; Jang, Sung-Ho; Hwang, Gab-Woon; Kim, Kwang-Won

2002-10-01

248

Maxillary first molar with an O-shaped root morphology: report of a case.  

PubMed

This case report is to present a maxillary first molar with one O-shaped root, which is an extended C-shaped canal system. Patient with chronic apical periodontitis in maxillary left first molar underwent replantation because of difficulty in negotiating all canals. Periapical radiographs and cone-beam computed tomography (CBCT) were taken. All roots were connected and fused to one root, and all canals seemed to be connected to form an O-shape. The apical 3 mm of the root were resected and retrograde filled with resin-modified glass ionomer. Intentional replantation as an alternative treatment could be considered in a maxillary first molar having an unusual O-shaped root. PMID:24008268

Shin, Yooseok; Kim, Yemi; Roh, Byoung-Duck

2013-12-01

249

Maxillary first molar with an O-shaped root morphology: report of a case  

PubMed Central

This case report is to present a maxillary first molar with one O-shaped root, which is an extended C-shaped canal system. Patient with chronic apical periodontitis in maxillary left first molar underwent replantation because of difficulty in negotiating all canals. Periapical radiographs and cone-beam computed tomography (CBCT) were taken. All roots were connected and fused to one root, and all canals seemed to be connected to form an O-shape. The apical 3 mm of the root were resected and retrograde filled with resin-modified glass ionomer. Intentional replantation as an alternative treatment could be considered in a maxillary first molar having an unusual O-shaped root. PMID:24008268

Shin, Yooseok; Kim, Yemi; Roh, Byoung-Duck

2013-01-01

250

Tuning of magnetic properties in cobalt ferrite by varying Fe+2 and Co+2 molar ratios  

NASA Astrophysics Data System (ADS)

Different grades of magnetic cobalt ferrite (CoFe2O4) nanoparticles were synthesized with various molar ratios of Fe+2 to Co+2 ions in the initial salt solutions by the co-precipitation method. The crystal structure and morphology of the nanoparticles are obtained from X-ray diffraction and transmission electron microscopy studies. Fourier transform infrared spectroscopy analysis exhibited the Fe-O stretching vibration ~540 cm-1, confirming the formation of metal oxide. The magnetic studies demonstrate that all of the nanoparticles are superparamagnetic at 300 K. The saturation magnetization and coercivity of the CoFe2O4 nanoparticles are affected by the molar ratios of Fe+2 to Co+2 ions. Among all the synthesized nanoparticles, the system with 75:25 molar ratio of Fe+2 to Co+2 ions with a particle size of 13 nm showed a high magnetization of 90 emu/g.

Biswal, Dipti; Peeples, Brianna N.; Peeples, Caryn; Pradhan, Aswini K.

2013-11-01

251

Asymmetry in mesial root number and morphology in mandibular second molars: a case report  

PubMed Central

Ambiguity in the root morphology of the mandibular second molars is quite common. The most common root canal configuration is 2 roots and 3 canals, nonetheless other possibilities may still exist. The presence of accessory roots is an interesting example of anatomic root variation. While the presence of radix entomolaris or radix paramolaris is regarded as a typical clinical finding of a three-rooted mandibular second permanent molar, the occurrence of an additional mesial root is rather uncommon and represents a possibility of deviation from the regular norms. This case report describes successful endodontic management of a three-rooted mandibular second molar presenting with an unusual accessory mesial root, which was identified with the aid of multiangled radiographs and cone-beam computed tomography imaging. This article also discusses the prevalence, etiology, morphological variations, clinical approach to diagnosis, and significance of supernumerary roots in contemporary clinical dentistry. PMID:24516829

Shetty, Shashit; Shekhar, Rhitu

2014-01-01

252

Formation of polyelectrolyte complexes with diethylaminoethyl dextran: charge ratio and molar mass effect.  

PubMed

The formation of polyelectrolyte complexes (PECs) between carboxymethyl pullulan and DEAE Dextran, was investigated, in dilute solution, with emphasis on the effect of charge density (molar ratio or pH) and molar masses. Electrophoretic mobility measurements have evidenced that insoluble PECs (neutral electrophoretic mobility) occurs for charge ratio between 0.6 (excess of polycation) and 1 (stoichiometry usual value) according to the pH. This atypical result is explained by the inaccessibility of some permanent cationic charge when screened by pH dependant cationic ones (due to the Hoffman alkylation). Isothermal titration calorimetry (ITC) indicates an endothermic formation of PEC with a binding constant around 10(5) L mol(-1). Finally asymmetrical flow field flow fractionation coupled on line with static multi angle light scattering (AF4/MALS) evidences soluble PECs with very large average molar masses and size around 100 nm, in agreement with scrambled eggs multi-association between various polyelectrolyte chains. PMID:25256478

Le Cerf, Didier; Pepin, Anne Sophie; Niang, Pape Momar; Cristea, Mariana; Karakasyan-Dia, Carole; Picton, Luc

2014-11-26

253

Survival and success rate of one-piece implant inserted in molar sites  

PubMed Central

Background: Recently, the use of one-piece implants (OPI) has become more popular. Since no reports specifically focus on OPIs inserted in molar areas, a retrospective study has been performed. Materials and Methods: A series of 36 OPIs (Diamond; BIOIMPLANT, Milan, Italy) were inserted into the molar area of patients admitted at the Dental Clinic, University of Chieti, Italy, for oral rehabilitation between January and December 2010. Results: In our series survival rate (SVR) and success rate (SCR) were 91.7% and 97%, respectively. Statistical analysis demonstrated that no studied variable has an impact on survival (i.e., lost implants) as well as on clinical success (i.e., crestal bone resorption). Conclusion: OPIs are reliable devices for oral rehabilitation in the molar areas. PMID:23814575

Carinci, Francesco

2012-01-01

254

Endodontic Management of Maxillary Second Molar with Two Palatal Roots: A Report of Two Cases  

PubMed Central

Endodontic treatment may sometimes fail because morphological features of the tooth adversely affect the treatment protocol. Maxillary second molars are recognized as usually having a single palatal root with a single palatal canal. The incidence of second palatal root in the maxillary second molar is very rare. Two cases are presented in this paper describing the endodontic management of a four-rooted maxillary second molar with two distinct palatal roots and canals and two distinct buccal roots and canals. Clinical examination and radiographs showed the presence of two palatal roots during the root canal procedure. The canals were biomechanically prepared with crown-down technique and obturated using lateral condensation technique with AH-Plus sealer. PMID:23304565

2012-01-01

255

Prevention of Localized Osteitis in Mandibular Third-Molar Sites Using Platelet-Rich Fibrin  

PubMed Central

Purpose. To review our experience utilizing platelet rich fibrin (PRF), which is reported to aid in wound healing of extraction sites, for the prevention of localized osteitis following lower third-molar removal. Materials and Methods. PRF was placed in the mandibular third-molar extraction sites, 200 sites total, on 100 consecutive patients treated in our practice, by the authors. The patients were managed with standard surgical techniques, intraoperative IV antibiotic/steroid coverage, and routine postoperative narcotic analgesics/short-term steroid coverage. All patients were reevaluated for localized osteitis within 7–10 days of the surgery. A comparison group consisted of 100 consecutive patients who underwent bilateral removal of indicated mandibular wisdom teeth and did not receive PRF placement within the lower third molar surgical sites. Results. The incidence of localized osteitis (LO) following removal of 200 lower third molars with simultaneous PRF placement within the extraction site was 1% (2 sites out of 200). The group of patients whose mandibular 3rd molar sockets were not treated with PRF demonstrated a 9.5% (19 sites out of 200) incidence of localized osteitis. The latter group also required 6.5 hours of additional clinical time to manage LO than the study group who received PRF. Conclusions. This retrospective review demonstrated that preventative treatment of localized osteitis can be accomplished using a low cost, autogenous, soluble, biologic material, PRF, that PRF enhanced third-molar socket healing/clot retention and greatly decreased the clinical time required for postoperative management of LO. PMID:23653648

Hoaglin, Donald R.; Lines, Gary K.

2013-01-01

256

The Partial Derivative Machine  

NSDL National Science Digital Library

Research has shown that students struggle to understand the use of partial derivatives in thermodynamics. We have designed an apparatus, which we have called a Partial Derivative Machine, that serves as a mechanical analogue of a thermodynamic system. Using this device, students have a tangible way to wrestle with issues related to partial derivatives and thermodynamics, such as which variables are held fixed, how many variables are independent, and how energy can be added to a system. In this paper, we present a description of the apparatus, an introduction to the associated activities, and an overview of how this apparatus can be connected to thermodynamic systems.

Sherer, Grant; Kustusch, Mary B.; Manogue, Corinne A.; Roundy, David J.

2014-01-31

257

Loss of molars early in life develops behavioral lateralization and impairs hippocampus-dependent recognition memory  

PubMed Central

Background Using senescence-accelerated mouse prone 8 (SAMP8), we examined whether reduced mastication from a young age affects hippocampal-dependent cognitive function. We anesthetized male SAMP8 mice at 8 weeks of age and extracted all maxillary molar teeth of half the animals. The other animals were treated similarly, except that molar teeth were not extracted. At 12 and 24 weeks of age, their general behavior and their ability to recognize novel objects were tested using the open-field test (OFT) and the object-recognition test (ORT), respectively. Results The body weight of molarless mice was reduced significantly compared to that of molar-intact mice after the extraction and did not recover to the weight of age-matched molar-intact mice throughout the experimental period. At 12 weeks of age, molarless mice showed significantly greater locomotor activity in the OFT than molar-intact mice. However, the ability of molarless mice to discriminate a novel object in the ORT was impaired compared to that of molar-intact mice. The ability of both molarless and molar-intact SAMP8 mice to recognize objects was impaired at 24 weeks of age. These results suggest that molarless SAMP8 mice develop a deficit of cognitive function earlier than molar-intact SAMP8 mice. Interestingly, both at 12 and 24 weeks of age, molarless mice showed a lateralized preference of object location in the encoding session of the ORT, in which two identical objects were presented. Their lateralized preference of object location was positively correlated with the rightward turning-direction preference, which reached statistical significance at 24 weeks of age. Conclusions Loss of masticatory function in early life causes malnutrition and chronic stress and impairs the ability to recognize novel objects. Hyperactivation and lateralized rotational behavior are commonly observed with dysfunction of the dopaminergic system, therefore, reduced masticatory function may deplete the mesolimbic and mesocorticolimbic dopaminergic systems to impair the cognitive functions of selective attention and recognition memory in the prefrontal cortex and the hippocampus. PMID:24387332

2014-01-01

258

Polarization volume holograms in layers of polymethylmethacrylate with phenanthrenequinone  

NASA Astrophysics Data System (ADS)

Polarization volume holograms are recorded in the polymethylmethacrylate layers that contain phenanthrenequinone at a molar content of 2.5-3%. The effect of the polarization of recording beams on the kinetics of diffraction efficiency and properties of holograms is analyzed. Polarization hologram recording in the polymethylmethacrylate layers with phenanthrenequinone and a relatively high optical stability of the holograms are demonstrated.

Marmysh, D. N.; Mahilny, U. V.

2013-11-01

259

Primary Mandibular First Molar with Single Root and Single Canal: A Case Report of a Rare Morphology  

PubMed Central

Single rooted primary mandibular first molar is a rare developmental anomaly. Literatures reveal that failure of invagination of Hertwig’s epithelial root sheath leads to this unusual root form. Thorough knowledge of root canal morphology and anatomical variations of primary teeth can help a pediatric dentist in successful root canal treatment. Hereby, we describe two cases of primary mandibular first molars with an unusual morphology as a single root called pyramidal molar.

Bahrololoomi, Zahra; Ghafourifard, Roya; Soleimani, Ali Asghar

2014-01-01

260

Cone beam computed tomography findings of ectopic mandibular third molar in the mandibular condyle: report of a case  

PubMed Central

Impaction of third molar is a common developmental abnormality. However, ectopic impaction of the mandibular third molar in condylar region is an extremely rare condition. This report describes a case of impacted tooth in the mandibular condyle without any associated pathologic condition. Also, this report presents the spatial relationship of the impacted mandibular third molar to the surrounding anatomic structures using cone beam computed tomography. PMID:22010071

2011-01-01

261

A clinical and microbiological comparative study of deep carious lesion treatment in deciduous and young permanent molars  

Microsoft Academic Search

The aim of this study was to compare one-visit indirect pulp treatment (IPT), two-visit IPT, and direct complete excavation\\u000a (DCE) of deciduous and young permanent molars with deep carious lesions from clinical and microbiological points of view.\\u000a One hundred thirty-five teeth (83 deciduous molars and 52 young permanent molars) were included in the study. The teeth were\\u000a randomly selected and

Ayse I. Orhan; Firdevs T. Oz; Berrin Ozcelik; Kaan Orhan

2008-01-01

262

Partial Testing Design  

Cancer.gov

Statistical Software Partial Testing Design (Written by Stuart G. Baker) New Approach (with ROC curves): See Baker SG, Pinsky P. A proposed design and analysis for comparing digital and analog mammography: special ROC methods for cancer screening. JASA.

263

Partial Derivatives: Geometric Visualization  

NSDL National Science Digital Library

This write-pair-share activity presents Calculus III students with a worksheet containing several exercises that require them to find partial derivatives of functions of two variables. Afterwards, a series of Web-based animations are used to illustrate the surface of each function, the path of the indicated partial derivative for a specified value of the variable and the value of the derivative at each point along the path.

Rutledge, James

264

Laparoscopic Partial Nephrectomy  

Microsoft Academic Search

\\u000a Laparoscopic partial nephrectomy is an excellent management option for small, superficial renal masses. With experience, larger\\u000a and deeper tumors can be addressed as well. Intermediate-term follow-up (3- and 5-year) suggests cancer control similar to\\u000a that of open surgery. The benefit of laparoscopy over open surgery is a briefer and less intense convalescence. The disadvantage\\u000a of laparoscopic partial nephrectomy, at least

265

PARTIAL TORUS INSTABILITY  

SciTech Connect

Flux ropes are now generally accepted to be the magnetic configuration of coronal mass ejections (CMEs), which may be formed prior to or during solar eruptions. In this study, we model the flux rope as a current-carrying partial torus loop with its two footpoints anchored in the photosphere, and investigate its stability in the context of the torus instability (TI). Previous studies on TI have focused on the configuration of a circular torus and revealed the existence of a critical decay index of the overlying constraining magnetic field. Our study reveals that the critical index is a function of the fractional number of the partial torus, defined by the ratio between the arc length of the partial torus above the photosphere and the circumference of a circular torus of equal radius. We refer to this finding as the partial torus instability (PTI). It is found that a partial torus with a smaller fractional number has a smaller critical index, thus requiring a more gradually decreasing magnetic field to stabilize the flux rope. On the other hand, a partial torus with a larger fractional number has a larger critical index. In the limit of a circular torus when the fractional number approaches 1, the critical index goes to a maximum value. We demonstrate that the PTI helps us to understand the confinement, growth, and eventual eruption of a flux-rope CME.

Olmedo, Oscar; Zhang Jie, E-mail: oolmedo@gmu.ed [Department of Computational and Data Sciences, George Mason University, 4400 University Drive, Fairfax, VA 22030 (United States)

2010-07-20

266

Study of O2 (1Delta) production in a glow discharge at large molar flow rates  

Microsoft Academic Search

O2 (1-Delta) production in an electric discharge is presently studied under the 5-10 mmol\\/sec molar flow rate and 10 Torr pressure required by an iodine laser. The production of large flow rates of singlet molecular oxygen and of atomic oxygen is demonstrated, and the possibility of initiating an iodine laser with discharged oxygen is ruled out.

L. Torchin; R. Jegou; H. Brunet

1983-01-01

267

Unerupted lower third molars and their influence on fractures of the mandibular angle and condyle.  

PubMed

Our aim was to assess the influence of the presence and state of impaction of mandibular third molars on the incidence of fractures of the mandibular angle and condyle. We designed a retrospective study of patients who presented for the treatment of mandibular fractures from January 2006 to April 2011. The independent variables were the presence and degree of impaction of lower third molars, and the outcome variables were the incidence of fractures of the mandibular angle and condyle. The information was acquired from hospital records and panoramic radiographs. Personal data included age, sex, mechanism of injuries, and number of fractures of the mandibular angle and condyle. We studied 110 fractures of the mandibular condyle and 80 of the angle. The incidence of fractures of the mandibular angle was higher in the group with incompletely erupted third molars (37/80, p<0.001) and that of condylar fractures was higher in the group without (67/110, p<0.001). An incompletely erupted third molar reduces the risk of condylar fractures and increases the risk of fractures of the mandibular angle. PMID:21764189

Patil, Pavan M

2012-07-01

268

Surgical Removal of Fractured Endodontic Instrument in the Periapex of Mandibular First Molar  

PubMed Central

The purpose of this article is to present the surgical removal of a broken endodontic file from the periapical region of the distal root of a mandibular first molar. The methods of diagnosis and measurement of the distance of the instrument to the adjacent vital structures in the periapical region was done with simple means and in an economical manner. PMID:25214740

Gandevivala, Adil; Parekh, Bandish; Poplai, Gaurav; Sayed, Aliya

2014-01-01

269

Caveats when Analyzing Ultra-high Molar Mass Polymers by SEC  

Technology Transfer Automated Retrieval System (TEKTRAN)

The analysis of ultra-high molar mass (M > 1 million g/mol) polymers via size-exclusion chromatography (SEC) presents a number of non-trivial challenges. Dissolution and full solvation may take days, as is the case for cellulose dissolution in non-complexing non degrading solvents; very low concent...

270

Stress distribution produced by the correction of the mandibular second molar in lingual crossbite.  

PubMed

The purpose of this study was to evaluate the stress distribution produced in the dentoalveolar system by a mandibular posterior crossbite appliance used for the correction of mandibular second molars in lingual version. A photoelastic model was fabricated using a photoelastic material (PL-3) to simulate alvelolar bone and ivory-colored resin teeth. The model was observed anteriorly and posteriorly with a circular polariscope and photographically recorded before and after activation of mandibular posterior crossbite appliances. An uncontrolled tipping and an extrusive force were generated when the traction force was applied on the buccal surface of the mandibular second molar. A controlled tipping and an intrusive force were generated when the traction force was applied on the lingual surface of the mandibular second molar. We concluded that to escape the extrusion and uncontrolled tipping that creates occlusal interferences associated with the correction of mandibular second molars in lingual version, the lingual traction force is more useful than the buccal traction force. PMID:12518954

Yoon, Young-Jooh; Jeong, Won-Jung; Jang, Sung-Ho; Hwang, Gab-Woon; Kim, Kwang-Won

2002-12-01

271

Is Overweight a Risk Factor for Adverse Events during Removal of Impacted Lower Third Molars?  

PubMed Central

Being overweight is recognised as a significant risk factor for several morbidities; however, the experience of the dentistry faculties focusing on this population is still low. The aim of the present study was to determine the occurrence of adverse events during removal of impacted lower third molars in overweight patients. A prospective cohort study was carried out involving overweight patients subjected to surgical removal of impacted lower third molar as part of a line of research on third molar surgery. Predictor variables indicative of the occurrence of adverse events during surgery were classified by their demographic, clinical, radiographic, and surgical aspects. Descriptive and bivariate statistics were computed. In total, 140 patients fulfilled the eligibility criteria, and 280 surgeries were performed. Patients' mean age was 25.1 ± 2.2 years, and the proportion of women to men was 3?:?1. Eight different adverse events during surgery were recorded. These events occurred in approximately 29.3% of cases and were significantly associated with predictor variables (P < 0.05). Excess weight is recognised as a risk factor for the high rate of adverse events in impacted third molar surgery. The study suggests that overweight patients are highly likely to experience morbidities. PMID:25548786

de Carvalho, Ricardo Wathson Feitosa; do Egito Vasconcelos, Belmiro Cavalcanti

2014-01-01

272

Estimation of legal age using calcification stages of third molars in living individuals.  

PubMed

The increased number of adolescents and young adults with unknown or inaccurately given date of birth is a current issue in justice and legal medicine. The objective of this study was to determine the extent to which third molar calcification stages assessed on panoramic X-rays could be useful as additional criteria for forensic age estimation in living individuals, focusing on the legally important ages 17 and 18. In a retrospective multi-center study, the developmental stage of each individual's third molar was analyzed using Demirjian's scale in 2360 cases. Additionally, sex, age and ancestry were assessed. Individuals with the lowest calcification stage of all present molars in stage H were ?18years with a likelihood of ?99.05% in the female (n=388), and ?99.24% in the male (n=482) population. The lowest calcification stage of all present third molars proved to be useful as an additional reliable criterion for the determination of an age ?18years. PMID:25498932

Streckbein, Philipp; Reichert, Isabelle; Verhoff, Marcel A; Bödeker, Rolf-Hasso; Kähling, Christopher; Wilbrand, Jan-Falco; Schaaf, Heidrun; Howaldt, Hans-Peter; May, Andreas

2014-12-01

273

A COMPARISON OF LIME AND ORANGE PECTIN BY HPSGC WITH MOLAR MASS AND VISCOSITY DETECTION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Pectin was acid extracted from lime albedo by microwave heating under pressure. Extraction times ranged from 1 to 10 minutes. Solubilized pectin was characterized for molar mass (M), rms radius of gyration (Rg) and intrinsic viscosity (IV) by HPSEC with online light scattering and viscosity detect...

274

Evaluation of the accuracy of different molar teeth measurements in assessing sex.  

PubMed

Teeth are considered to be a very useful tissue for sex determination and molars are among the most dimorphic teeth. Even though mesiodistal (MD) and buccolingual (BL) crown diameters are usually employed for sex assessment, alternative measurements like MD and BL cervical diameters as well as crown and cervical diagonal diameters have been developed. This study explores the utility of crown and cervical MD, BL and diagonal measurements of molars in sex assessment when used separately. A total of 254 permanent molars (excluded third molars) from 101 individuals (51 males, 50 females) from the Athens Collection were examined. Stepwise discriminant analysis was used to evaluate the accuracy of each diameter group in assessing sex. It was found that the accuracy ranges from 65.5 to 88.4 %. Cervical diagonal diameters are the most accurate followed by crown diagonal diameters, and crown and cervical MD and BL diameters. Therefore the high classification accuracy of diagonal diameters show that these measurements are more reliable for sex determination than the traditional MD and BL and can be considered a promising method for sex assessment from human teeth. PMID:22926774

Zorba, Eleni; Spiliopoulou, Chara; Moraitis, Konstantinos

2013-03-01

275

A familial case of recurrent hydatidiform molar pregnancies with biparental genomic contribution  

Microsoft Academic Search

Hydatidiform mole is a benign trophoblastic neoplasia characterized by an abnormal development of the embryo and proliferation of placental villi. Using microsatellite markers amplified by the polymerase chain reaction, we have performed a genetic study on eight independent molar tissues occurring in two sisters. Karyotype and genotype data demonstrate a diploid and biparental constitution in seven of the analyzed moles

Mazen N. Helwani; Muhieddine Seoud; Laila Zahed; Ghazi Zaatari; Ali Khalil; Rima Slim

1999-01-01

276

Molar Mass Profiling of Synthetic Polymers by Free-Solution Capillary Electrophoresis of  

E-print Network

Molar Mass Profiling of Synthetic Polymers by Free-Solution Capillary Electrophoresis of DNA of the DNA-polymer conju- gates as a function of the size of the uncharged PEG tail. This provides a profile) (PEG)), based upon single-monomer resolution of DNA-polymer conjugates by free-solution capillary

Barron, Annelise E.

277

How to measure and predict the molar absorption coefficient of a protein  

Microsoft Academic Search

The molar absorption coefficient, E, of a protein is usually based on concentrations measured by dry weight, ni- trogen, or amino acid analysis. The studies reported here suggest that the Edelhoch method is the best method for measuring E for a protein. (This method is described by Gill and von Hippel (1989, Anal Biochem 182:319- 3261 and is based on

C. Nick Pace; Felix Vajdos; Lanette Fee; Gerald Grimsley; Theronica Gray

1995-01-01

278

Solution properties of high-molar-mass hyaluronans: the biopolymer degradation by ascorbate  

Microsoft Academic Search

An accurate molecular characterization, molar mass and size distributions, of 10 hyaluronan (HA) samples was performed by using a multi-angle light scattering detector connected on-line to a size exclusion chromatographic system. The dynamic viscosity ? of the HA solutions was investigated using a rotational viscometer. On monitoring the sample dynamic viscosity for up to 5h, a small however constant increase

Ladislav Šoltés; Katarína Valachová; Raniero Mendichi; Grigorij Kogan; Juergen Arnhold; Peter Gemeiner

2007-01-01

279

Age at first molar emergence in Lufengpithecus lufengensis and its implications for life-history evolution.  

PubMed

The late Miocene hominoid Lufengpithecus from Yunnan Province, China, is crucial for understanding hominoid evolution in Asia. Given that age at first permanent molar emergence is a key life-history trait in primates, the present study determined the age at death of the Lufengpithecus lufengensis juvenile PA868, which was in the process of erupting its first molar. Using a perikymata periodicity of 7-11 days, along with estimation of cusp formation time and the postnatal delay of crown mineralization, perikymata counts obtained from the permanent central incisor and canine germs indicate that the age at death of PA868 was 2.4-4.5 years based on the central incisor germ, and 2.5-4.7 years based on the canine germ. The age at the first molar emergence was actually slightly younger (by about 0.3 years), as demonstrated by tiny wear facets on this tooth, which indicate that gingival emergence had occurred sometime before death. The average age at first molar emergence of Lufengpithecus lufengensis PA868 is estimated to be 3.2-3.3 years, with a range of 2.1-4.4 years. In comparison to extant primates and other fossil hominoids, the life history of Lufengpithecus lufengensis is similar to that of extant great apes and the Miocene hominoids Afropithecus turkanensis and Sivapithecus parvada, as well as Plio-Pleistocene Australopithecus, and different from monkeys, gibbons, and modern humans. PMID:18037472

Zhao, Lingxia; Lu, Qingwu; Zhang, Wending

2008-02-01

280

Comparative trial between the use of amoxicillin and amoxicillin clavulanate in the removal of third molars  

PubMed Central

Objectives: The purpose of this study was to compare the use of amoxicillin (1g) vs amoxicillin and clavulanate (875/125mg) after extraction of retained third molars for prevention of infectious complications. Study Design: The study involved 546 patients attending for removal a retained third molar and divided in to two groups: Group 1 - amoxicillin and clavunate (875/125mg) group (n=257) and Group 2 - amoxicillin (1g) group (n=289). All patients were recalled for investigating the possibility of infection, presence of diarrhea and further analgesic intake. Results: From a total of 546 patients, the frequency of infection was 1.4%, without no statistically differences between the two groups. Group 1 showed statistically higher presence of patients with gastrointestinal complications (p>0.05). In 546 patients, 2.7% of patients reported severe pain that would not relieve with medication. Conclusions: The results of our study show that the use of amoxicillin (1g) and amoxicillin and clavunate (875/125mg) is similar efficacious in preventing infection after retained third molar extraction but amoxicillin and clavunate (875/125mg) produces more gastrointestinal discomfort. Key words:Amoxicillin, clavulanate, third molars, complications. PMID:24880449

Iglesias-Martín, Fernando; García-Perla-García, Alberto; Yañez-Vico, Rosa; Rosa, Elena; Arjona-Gerveno, Esther; González-Padilla, Juan D.; Gutierrez-Pérez, Jose L.

2014-01-01

281

Vienna-Chicago: the cultural transformation of the model system of the un-opposed molar.  

PubMed

The discussion over the roles of genes and environment on the phenotypical specification of organisms has held a central role in science philosophy since the late 19(th) century and has re-emerged in today's debate over genetic determinism and developmental plasticity. In fin-de-siecle Vienna, this debate coincided with a philosophical debate over empiricism/materialism versus idealism/vitalism. Turn-of-the-century Vienna's highly interdisciplinary environment was also the birthplace for the model system of the un-opposed molar. The un-opposed molar system features new tissue formation at the roots of teeth and tooth drift once opposing teeth are lost. The un-opposed molar model system was revived by a group of Viennese scientists who left Vienna during the Nazi period to address Vienna's questions about evolution and heredity and about genes and environment in Chicago's post-WWII scientific exile community. Here we are using the colorful history of the un-opposed molar to investigate the role of culture and method in the scientific evolution of a model system. PMID:17621674

Luan, Xianghong; Diekwisch, Thomas G H

2007-08-01

282

Anatomical Study of C-Shaped Canals in Mandibular Second Molars by Analysis of Computed Tomography  

Microsoft Academic Search

The aim of this study was to investigate the prevalence and configuration of the C-shaped canal using serial axial computed tomography images of the mandibular second molars that had not been restored severely or treated endodontically, and to compare the thickness of the remaining tooth structure from the center of the canal to the outer surface of the deepest groove

Guang-Chun Jin; Seong-Jong Lee; Byoung-Duck Roh

2006-01-01

283

Sensibility and taste alterations after impacted lower third molar extractions. A prospective cohort study  

PubMed Central

Objectives: To determine the incidence, severity and duration of lingual tactile and gustatory function impairments after lower third molar removal. Study Design: Prospective cohort study with intra-subject measures of 16 patients undergoing lower third molar extractions. Sensibility and gustatory functions were evaluated in each subject preoperatively, one week and one month after the extraction, using Semmes-Weinstein monofilaments and 5 different concentrations of NaCl, respectively. Additionally, all patients filled a questionnaire to assess subjective perceptions. Results: Although patients did not perceive any sensibility impairments, a statistically significant decrease was detected when Semmes-Weinstein monofilaments. This alteration was present at one week after the surgical procedure and fully recovered one month after the extraction. There were no variations regarding the gustatory function. Conclusions: Lower third molar removal under local anesthesia may cause light lingual sensibility impairment. Most of these alterations remain undetected to patients. These lingual nerve injuries are present one week after the extraction and recover one month after surgery. The taste seems to remain unaffected after these procedures. Key words:Lingual nerve, third molar, nerve injury, paresthesia, surgical extraction PMID:22322520

Ridaura-Ruiz, Lourdes; Valmaseda-Castellón, Eduard; Berini-Aytés, Leonardo; Gay-Escoda, Cosme

2012-01-01

284

Developmental connections between cranial components and the emergence of the first permanent molar  

Microsoft Academic Search

The age of emergence of the first molar (M1) is a developmental event correlated with many variables of primate life history, such as adult brain size. The evolution of human life history is characterized by the inclusion of child- hood, which takes place between weaning and M1 emergence. Children still depend on adults for nutrition due to their small digestive

Marina L. Sardi; Fernando Ramírez Rozzi

2007-01-01

285

Characterization of Alternan, a high molar mass polysaccharide from Leuconostoc mesenteroides, by FFF-MALS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Native alternan is a high molar mass homopolymer of D-glucose produced by some strains of the bacterium Lueconostoc mesenteroides. It consists of glucose units that alternate their linkages between alpha-(1-6) and alpha-(1-3) between glucosyl units. The glucose units contained in the polysaccharid...

286

Combined CO 2 reforming and partial oxidation of n-heptane on noble metal zirconia catalysts  

Microsoft Academic Search

The combined CO2 reforming and partial oxidation (POX) of n-heptane was studied on various noble metal zirconia catalysts between 700 and 900°C. The activity order of the metals was Rh>Pd>Ir>Pt. Selectivity to syngas increased with the activity of the catalysts but the H2 to CO molar ratio decreased. The activity and selectivity of the 0.25wt% Rh\\/ZrO2 catalyst were close to

K. J. Puolakka; S. Juutilainen; A. O. I. Krause

2006-01-01

287

Modifications in Canal Anatomy of Curved Canals of Mandibular First Molars by two Glide Path Instruments using CBCT  

PubMed Central

Background: The creation of glide path reduces the risk of instrument breakage. Glide path is created before using NiTi rotary instrumentation Aim: This study compared the changes in the root canal anatomy after creation of glide path using Path Files (PF) and V Glide Path 2 (VGP2) using Cone Beam Computed Tomography (CBCT). Materials and Methods: Hundred extracted mandibular first molars with curved mesial roots, curvature angles ranging within 20-30 degrees were assigned into two groups (n = 50 each). Glide path was prepared using PF (Group I) and VGP2 (Group II). CBCT images were obtained before and after instrumentation. The technical outcomes were compared at 0, 1, 2, 3, 5 and 7mm intervals. The data was analyzed using t-test and Chi-square test. Result: There was a statistical difference between the root canal curvatures and working time between the two groups (p < 0.05). Canals transported towards the distal side in Group II but there was a slight mesial transportation in Group I at 0mm. Group I exhibited a better centric ability except at 1mm interval (p > 0.05). The changes in the volume were statistically significant only at 2mm interval (p < 0.05). The difference in the cross sectional area was not statistically significant at any interval (p > 0.05). Conclusion: Within the limits of this study the rotary Nickel Titanium Path Files appeared to be suitable instruments for safe and easy creation of glide path.

Manchanda, Nayasha

2014-01-01

288

Student (Mis)application of Partial Differentiation to Material Properties  

NSDL National Science Digital Library

Students in upper-level undergraduate thermodynamics courses were asked about the relationship between the complementary partial derivatives of the isothermal compressibility and the thermal expansivity of a substance. Both these material properties can be expressed with first partial derivatives of the system volume. Several of the responses implied difficulty with the notion of variables held fixed in a partial derivative. Specifically, when asked to find the partial derivative of one of these quantities with respect to a variable that was initially held fixed, a common response was that this (mixed second) partial derivative must be zero. We have previously reported other related difficulties in the context of the Maxwell relations, indicating persistent confusion applying partial differentiation to state functions. We present results from student homework and examination questions and briefly discuss an instructional strategy to address these issues.

Bucy, Brandon; Thompson, John R.; Mountcastle, Donald B.

2007-11-25

289

Methanol partial oxidation reformer  

DOEpatents

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.

Ahmed, S.; Kumar, R.; Krumpelt, M.

1999-08-24

290

[Partial breast irradiation].  

PubMed

Owing to breast cancer screening, breast cancer is more and more diagnosed at early stage. For those breast cancer women, breast conserving treatment (breast conserving surgery followed by whole breast irradiation) is commonly used since many years. New radiation modalities have been recently developed in early breast cancers particularly accelerated partial breast irradiation (APBI). Among all techniques of radiotherapy, 3D-conformal APBI and intraoperative radiotherapy (IORT) are the main modalities of radiotherapy used. The present review states on indications, treatment modalities and updated results of local control and side effects of partial breast irradiation. PMID:24445657

Bourgier, Céline; Lemanski, Claire; Fenoglietto, Pascal; Riou, Olivier; Dubois, Jean Bernard; Azria, David

2014-01-01

291

GENERAL: Low-temperature heat capacities and standard molar enthalpy of formation of 4-(2-aminoethyl)-phenol (C8H11NO)  

NASA Astrophysics Data System (ADS)

This paper reports that low-temperature heat capacities of 4-(2-aminoethyl)-phenol (C8H11NO) are measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 400 K. A polynomial equation of heat capacities as a function of the temperature was fitted by the least square 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 the interval of 5 K. The energy equivalent, ?calor, of the oxygen-bomb combustion calorimeter has been determined from 0.68 g of NIST 39i benzoic acid to be ?calor = (14674.69±17.49)J.K-1. The constant-volume energy of combustion of the compound at T = 298.15 K was measured by a precision oxygen-bomb combustion calorimeter to be ?cU = -(32374.25±12.93)J.g-1. The standard molar enthalpy of combustion for the compound was calculated to be ?cHmominus = -(4445.47 ± 1.77) k. J · mol-1 according to the definition of enthalpy of combustion and other thermodynamic principles. Finally, the standard molar enthalpy of formation of the compound was derived to be ?fHmominus(C8H11NO, s) = -(274.68 ± 2.06) kJ · mol-1, in accordance with Hess law.

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

2008-09-01

292

Low Temperature Heat Capacities and Standard Molar Enthalpy of Formation of 2-Pyrazinecarboxylic Acid (C5H4N2O2)(s).  

PubMed

Low-temperature heat capacities of 2-pyrazinecarboxylic acid (C5H4N2O2)(s) were measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 400 K. A polynomial equation of heat capacities as a function of temperature was fitted by 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 10 K intervals. The constant-volume energy of combustion of the compound at T = 298.15 K was measured by a precision rotating-bomb combustion calorimeter to be ?cU = -(17839.40 ± 7.40) J g-1. The standard molar enthalpy of combustion of the compound was determined to be ?cH0m = -(2211.39 ± 0.92) KJ mol-1, according to the definition of combustion enthalpy. Finally, the standard molar enthalpy of formation of the compound was calculated to be ?fH0m = -(327.82 ± 1.13) kJ mol-1 in accordance with Hess law. PMID:24061733

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

2010-06-01

293

A histological and micro-CT investigation in to the effect of NGF and EGF on the periodontal, alveolar bone, root and pulpal healing of replanted molars in a rat model - a pilot study  

PubMed Central

Background This study aims to investigate, utilising micro-computed tomography (micro-CT) and histology, whether the topical application of nerve growth factor (NGF) and/or epidermal growth factor (EGF) can enhance periodontal, alveolar bone, root and pulpal tissue regeneration while minimising the risk of pulpal necrosis, root resorption and ankylosis of replanted molars in a rat model. Methods Twelve four-week-old male Sprague-Dawley rats were divided into four groups: sham, collagen, EGF and NGF. The maxillary right first molar was elevated and replanted with or without a collagen membrane impregnated with either the growth factors EGF or NGF, or a saline solution. Four weeks after replantation, the animals were sacrificed and the posterior maxilla was assessed using histological and micro-CT analysis. The maxillary left first molar served as the control for the corresponding right first molar. Results Micro-CT analysis revealed a tendency for all replanted molars to have reduced root length, root volume, alveolar bone height and inter-radicular alveolar bone volume. It appears that the use of the collagen membrane had a negative effect while no positive effect was noted with the incorporation of EGF or NGF. Histologically, the incorporation of the collagen membrane was found to negatively affect pulpal, root, periodontal and alveolar bone healing with pulpal inflammation and hard tissue formation, extensive root resorption and alveolar bone fragmentation. The incorporation of EGF and NGF did not improve root, periodontal or alveolar bone healing. However, EGF was found to improve pulp vascularisation while NGF-improved pulpal architecture and cell organisation, although not to the level of the control group. Conclusions Results indicate a possible benefit on pulpal vascularisation and pulpal cell organisation following the incorporation of EGF and NGF, respectively, into the alveolar socket of replanted molars in the rat model. No potential benefit of EGF and NGF was detected in periodontal or root healing, while the use of a collagen membrane carrier was found to have a negative effect on the healing response. PMID:24393534

2014-01-01

294

Partial trisomy 3q  

Microsoft Academic Search

A new case of partial trisomy 3q is reported in a 5-year-old female with severe congenital malformations and psychomotor retardation. A review of the literature, with a total of 11 patients, allows us to conclude that the clinical picture reminiscent of the Cornelia de Lange syndrome is caused by the trisomic state.

E. Yunis; L. Quintero; A. Castefieda; E. Ramirez; M. Leibovici

1979-01-01

295

Partial Constraint Satisfaction  

Microsoft Academic Search

A constraint satisfaction problem involves finding values for variables subject to constraints on which combinations of values are allowed. In some cases it may be impossible or impractical to solve these problems completely. We may seek to partially solve the problem, in particular by satisfying a maximal number of constraints. Standard backtracking and local consistency techniques for solving constraint satisfaction

Eugene C. Freuder; Richard J. Wallace

1995-01-01

296

Implementing partial least squares  

Microsoft Academic Search

Partial least squares (PLS) regression has been proposed as an alternative regression technique to more traditional approaches such as principal components regression and ridge regression. A number of algorithms have appeared in the literature which have been shown to be equivalent. Someone wishing to implement PLS regression in a programming language or within a statistical package must choose which algorithm

M. C. Denham

1995-01-01

297

Familial partial 14 trisomy.  

PubMed Central

Four children in the same family have 47, +der (14), t(9;14) (p24;q21). Their mothers are sisters with 46,XX,t(9;14) (p24;q21). Clinical features of the children are similar to those of others reported to have partial 14 trisomy. Images PMID:469889

Miller, J Q; Willson, K; Wyandt, H; Jaramillo, M A; McConnell, T S

1979-01-01

298

SUPERCRITICAL WATER PARTIAL OXIDATION  

Microsoft Academic Search

In 2000, General Atomics was selected by DOE's Hydrogen Program to perform cooperatively- funded research on supercritical water partial oxidation (SWPO) of biomass, municipal solid waste (MSW), and high-sulfur coal to generate hydrogen. Phase I of this research is being performed in GA's privately-funded supercritical water (SCW) pilot plant at its San Diego, CA facilities. This pilot plant is a

N. W. Johanson; M. H. Spritzer; G. T. Hong; W. S. Rickman

299

Volume graphics  

Microsoft Academic Search

Volume graphics, which employs a volume buffer of voxels for 3D scene representation, is discussed. Volume graphics offers advantages over surface graphics: it is viewpoint independent, insensitive to scene and object complexity, and suitable for the representation of sampled and simulated data sets. Moreover, geometric objects can be mixed with these data sets. Volume graphics supports the visualization of internal

Arie E. Kaufman; Daniel Cohen-Or; Roni Yagel

1993-01-01

300

Improving the developability profile of pyrrolidine progesterone receptor partial agonists  

SciTech Connect

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.

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. (GSKPA)

2010-09-17

301

Artefacts in Cone Beam CT Mimicking an Extrapalatal Canal of Root-Filled Maxillary Molar  

PubMed Central

Despite the advantages of cone-beam computed tomography (CBCT), the images provided by this diagnostic tool can produce artifacts and compromise accurate diagnostic assessment. This paper describes an endodontic treatment of a maxillary molar where CBCT images suggested the presence of a nonexistent third root canal in the palatal root. An endodontic treatment was performed in a first maxillary molar with palatal canals, and the tooth was restored with a cast metal crown. The patient returned four years later presenting with a discomfort in chewing, which was reduced after occlusal adjustment. CBCT was prescribed to verify additional diagnostic information. Axial scans on coronal, middle, and apical palatal root sections showed images similar to a third root canal. However, sagittal scans demonstrated that these images were artifacts caused by root canal fillings. A careful interpretation of CBCT images in root-filled teeth must be done to avoid mistakes in treatment. PMID:23606995

Camilo, Carla Cristina; Brito-Júnior, Manoel; Faria-e-Silva, André Luis; Quintino, Alex Carvalho; de Paula, Adrianne Freire; Cruz-Filho, Antônio Miranda; Sousa-Neto, Manoel Damião

2013-01-01

302

Mini-implant-borne Pendulum B appliance for maxillary molar distalisation: design and clinical procedure.  

PubMed

A treatment objective of upper molar distalisation may often be required during the correction of a malocclusion. Distalisation is not only indicated for the management of Class II patients, but also for Class III surgery patients who require decompensation in the upper arch if upper incisor retrusion is needed. Unfortunately, most conventional intra-oral devices for non-compliance maxillary molar distalisation experience anchorage loss. A Pendulum type of appliance and a mini-implant-borne distalisation mechanism have been designed which can be inserted at chair-side, without a prior laboratory procedure and immediately after mini-implant placement. For re-activation purposes, a distal screw may be added to the Pendulum B appliance. PMID:25549527

Wilmes, Benedict; Katyal, Vandana; Drescher, Dieter

2014-11-01

303

Sharp Curvature of Premolar Resulting in External Apical Root Resorption of the Neighbouring Molar  

PubMed Central

This case report describes an external apical root resorption resulted from the unusual root morphology of the neighbouring tooth. A 28-year-old female was referred to the department of endodontics with a complaint of intense pain in her maxillary second premolar tooth. The clinical and radiographical evaluation revealed an external apical resorption in the mesial root of the maxillary first molar, which shows close proximity to the severely curved root of the premolar. A successful root canal treatment of the premolar was performed using anticurvature filing method. However, molar tooth received no curative treatment. One-year followup of the apical external resorption did not show any progression. External apical root resorption affecting single permanent tooth may be induced from the pressure exerted during the eruption of the adjacent tooth with unusual root morphology. The preferred approach for the management of such apical resorption cases includes long-term observation and no curative treatment. PMID:22567442

Ulusoy, Özgür ?lke Atasoy

2011-01-01

304

Endodontic treatment of a mandibular first molar with 8 canals: a case report  

PubMed Central

Presented here is a case where 8 canals were located in a mandibular first molar. A patient with continuing pain in mandibular left first molar even after completion of biomechanical preparation was referred by a dentist. Following basic laws of the pulp chamber floor anatomy, 8 canals were located in three steps with 4 canals in each root. In both of the roots, 4 separate canals commenced which joined into two canals and exited as two separate foramina. At 6 mon follow-up visit, the tooth was found to be asymptomatic and revealed normal radiographic periapical area. The case stresses on the fact that understanding the laws of pulp chamber anatomy and complying with them while attempting to locate additional canals can prevent missing canals.

Acharya, Shashi Rashmi; Sharma, Padmaja

2015-01-01

305

Degradation of high-molar-mass hyaluronan and characterization of fragments.  

PubMed

A sample of high-molar mass hyaluronan was oxidized by seven oxidative systems involving hydrogen peroxide, cupric chloride, ascorbic acid, and sodium hypochlorite in different concentrations and combinations. The process of the oxidative degradation of hyaluronan was monitored by rotational viscometry, while the fragments produced were investigated by size-exclusion chromatography, matrix-assisted laser desorption ionization-time-of-flight mass spectrometry, and non-isothermal chemiluminometry. The results obtained imply that the degradation of hyaluronan by these oxidative systems, some of which resemble the chemical combinations present in vivo in the inflamed joint, proceeds predominantly via hydroxyl radicals. The hyaluronan fragmentation occurred randomly and produced species with rather narrow and unimodal distribution of molar mass. Oxidative degradation not only reduces the molecular size of hyaluronan but also modifies its component monosaccharides, generating polymer fragments that may have properties substantially different from those of the original macromolecule. PMID:17691842

Soltés, L; Kogan, G; Stankovska, M; Mendichi, R; Rychlý, J; Schiller, J; Gemeiner, P

2007-09-01

306

Morphologic analysis of third-molar maturity by digital orthopantomographic assessment.  

PubMed

Accurate timing of the eruption of first and permanent teeth is an important parameter in forensic odontology to establish the age of dead or live individuals. Determination of adulthood may determine, for example, whether an individual convicted of a crime is sentenced as an adult and incarcerated in a state penal institution or as a juvenile and sent to a juvenile camp. At present, there is a large immigrant population in Italy, and young foreign criminals sometimes have false passports bearing a later birth date, with the aim of evading punishment. In such circumstances, age determination is becoming a significant forensic issue.Late in adolescence, after formation of the premolars and canines, only the third molars continue to develop. According to several studies, although the third molars are the most variable teeth in the dentition, they remain the most reliable biologic indicator available for estimation of age during the middle teens and early twenties.In this study, the authors test the possibilities offered by orthopantomography executed by means of digital technology, with the aim of exploiting the advantages of the computerized digital technique compared with the conventional technique, to determine adult age on the basis of root development of the third molar.Digital radiography is simple to use, quick, and effective, allowing superimposition and enlargement; the images can be electronically stored and transported. In comparison with traditional orthopantomography, the digital technique features greater diagnostic accuracy of some anatomic structures: upper and lower front teeth, root apexes, floor of the nasal fossa and maxillary sinus, nasal septum, mandibular condylus. Moreover, digital orthopantomography suffers less from artifacts.The digital orthopantomographies of 83 Caucasian subjects (43 females and 40 males) aged between 16 and 22 years were analyzed in standard conditions, assessing the degree of maturation of the upper and lower third molars. A standardized computer procedure was used to acquire the x-ray images, recording 3 per plate: the overall orthopantomography and 2 enlargements of optical type of the left and right sides, to reveal the third molars while maintaining unaltered the image resolution.For the analysis, the authors adopted Demirjian's staging system that classifies development of the third molar in 8 stages (A, B, C, D, E, F, G, H) on the basis of morphologic criteria. This has been statistically proved to feature notable precision and high predictive ability.To assess any sex-related variations in mineralization speed, the series was subdivided by gender. The study demonstrated that such differences are more evident under the age of 18 years.Overall, the observation of 245 third molars showed faster development of the upper than the lower third molars, a prevalence of stages D to G in the age range between 16 and 18 years, and a clear predominance of stage H in individuals over 18 years of age. Finally, an intermediate stage between G and H was demonstrated in subjects aged between 17 and 21 years. PMID:19749618

Introna, Francesco; Santoro, Valeria; De Donno, Antonio; Belviso, Maura

2008-03-01

307

Endodontic Retreatment of a Mandibular Second Molar with four Separate Roots: A Case Report  

PubMed Central

Aberrations in the root canal anatomy are a commonly occurring phenomenon. Although the mandibular second molar is commonly a bi-rooted tooth with an uncomplicated endodontic anatomy, variations have to be considered every time endodontic therapy is performed. This case report describes the non-surgical endodontic retreatment performed on a mandibular second molar with four seperate roots and canals. ProTaper Universal rotary nickel-titanium instruments (Dentsply Maillefer, Ballaigues, Switzerland) for treatment and retreatment were used to remove the old gutta percha and to clean and shape all root canals, followed by the complete obturation of root canal system. Post-operative CBCT scan was taken to confirm the quality of the performed treatment. PMID:24783160

Idris, Mohamed; Sakkir, Nasil; KJ, Nandakishore; Kini, Annapurna

2014-01-01

308

Implication of Sphingomyelin/Ceramide Molar Ratio on the Biological Activity of Sphingomyelinase  

PubMed Central

Abstract Sphingolipid signaling plays an important, yet not fully understood, role in diverse aspects of cellular life. Sphingomyelinase is a major enzyme in these signaling pathways, catalyzing hydrolysis of sphingomyelin to ceramide and phosphocholine. To address the related membrane dynamical structural changes and their feedback to enzyme activity, we have studied the effect of enzymatically generated ceramide in situ on the properties of a well-defined lipid model system. We found a gel-phase formation that was about four times faster than ceramide generation due to ceramide-sphingomyelin pairing. The gel-phase formation slowed down when the ceramide molar ratios exceeded those of sphingomyelin and stopped just at the solubility limit of ceramide, due to unfavorable pairwise interactions of ceramide with itself and with monounsaturated phosphatidylcholine. A remarkable correlation to in vitro experiments suggests a regulation of sphingomyelinase activity based on the sphingomyelin/ceramide molar ratio. PMID:20643068

Boulgaropoulos, Beate; Amenitsch, Heinz; Laggner, Peter; Pabst, Georg

2010-01-01

309

Iatrogenic molar borings in 18th and early 19th century Native American dentitions.  

PubMed

Six iatrogenic dental borings were identified in four individuals of a Native American skeletal collection from an 18th and early 19th century Middle Columbia River burial site. The borings, all in maxillary first molars with severe dental attrition and secondary dentin, demonstrate striated walls and associated periapical alveolar lesions. An ethnographic review of the subsistence pattern during the burial period indicates a diet that is consistent in dental attrition with other riverine fisher-hunter-gathers. Histological changes of dental pulp tissue during the process of attrition may result in dental necrosis. Access into the pulp chamber is a technique used to drain necrotic fluid. A common Euro-American therapeutic dental practice of the 18th and 19th centuries for diseases of the pulp was dental extraction. Multiple dental borings indicate that the practice of molar drilling into the pulp chamber was an effective and independent technique used by the Wishram and Wasco people. PMID:15486962

Seidel, John C; Colten, Roger H; Thibodeau, Edward A; Aghajanian, John G

2005-05-01

310

Four-Rooted Mandibular First Molar with an Unusual Developmental Root Fusion Line: A Case Report  

PubMed Central

The paper describes the anatomical variation of four roots in a mandibular permanent first molar diagnosed using multiple angulated preoperative radiographs and its successful nonsurgical endodontic management. Careful observation and exploration of the pulpal floor using a dental operating microscope revealed a peculiar developmental root fusion line on the pulp chamber floor. Based on the above observation, a correlation between this unusual line and the existence of additional roots has been proposed and discussed. PMID:22792498

Kottoor, Jojo; Albuquerque, Denzil Valerian; Velmurugan, Natanasabapathy; Sumitha, Mylswamy

2012-01-01

311

Immunodetection of Osteopontin at Sites of Resorption in the Pulp of Rat Molars  

Microsoft Academic Search

SUMMARY Osteopontin (OPN) has been proposed to act as a substrate for osteoclast ad- hesion during bone resorption. The aim of the present study was to examine the presence and distribution of OPN at sites of resorption in traumatized radicular pulp. The upper first molars of 6-week-old male Sprague-Dawley rats were luxated and then repositioned in the original sockets. The

Yoshihito Shimazu; Antonio Nanci; Takaaki Aoba

312

Excess molar enthalpies for mixtures of supercritical carbon dioxide and water + ethanol solutions  

Microsoft Academic Search

Excess molar enthalpies (H E m) for mixtures of supercritical CO2 and ethanol aqueous solutions were measured at 323.15 K and 7.64 and 15.00 MPa using an isothermal high-pressure flow calorimeter. H E m values obtained at the lower pressure are very exothermic while those obtained at the higher pressure are moderately endothermic. H E m for CO2 +H 2O

Eduardo P; Yolanda S ´ anchez-Vicente; Albertina Caba; Juan A. R. Renuncio

2005-01-01

313

Administration of bisphosphonate (ibandronate) impedes molar tooth movement in rabbits: A radiographic assessment  

PubMed Central

Introduction: Bisphosphonate (Bp)-ibandronate is a pharmacological agent, exhibits antiosteoclastic or antiresorptive activity and used to treat osteolytic or osteopenic disorders. BP-ibandronate may also interfere during orthodontic tooth movement. The aim of this study was to examine the influence of locally administered Bp-ibandronate on experimental tooth movement in rabbits. Materials and Methods: Twenty rabbits were divided into two groups- “10” served as Group-1 (control) and other “10” as Group-2 (experimental). Both groups received nickel-titanium closed coil springs with 100 g force between mandibular molar and incisors. Group-1 animals received 1 ml normal saline and Group-2 animals received ibandronate solution (0.3 mg/kg body weight) locally, mesial to the mandibular molar on the 1st, 7th, and 14th day of the experiment. A total of “40” lateral cephalograms were taken from both groups on the 1st and 21st day using a digital X-ray unit (Siemens X-ray systems, 300 mA Pleomophos analog, 2008, Germany). Individually, each animal's radiograph was traced manually and superimposed. The molar tooth movement was measured with the help of a standard metric scale. Results: The Student's t-test has been done to compare the mean values of Group-1 (4.650 ± 0.363) and Group-2 (2.030 ± 0.291) and the difference was statistically significant (P < 0.001). Conclusion: The retarded molar tooth movement was noticed in local drug administered rabbits, which could be beneficial in orthodontics to control the undesired tooth movement. PMID:25210364

Venkataramana, V.; Kumar, S. Sathesh; Reddy, B. Vishnuvardhan; Cherukuri, A. Sreekanth; Sigamani, K. Raja; Chandrasekhar, G.

2014-01-01

314

Effects of localmelatonin application on post-extraction sockets after third molar surgery. A pilot study  

PubMed Central

Objectives: The purpose of this study was to assess the anti-inflammatory, analgesic and osteogenic early effects of melatonin on post-extraction sockets ofpatients requiring third molars extraction. Study Design: A randomized, triple-blind clinical trial was made using a split-mouth design. Both lower third molars of 10 patients were extracted and 3 mg of local melatonin or placebo were applied. Concentrations of interleukin-6 and nitrotyrosine were determined on samples of the clot from the socket by independent ELISA tests. Radiographic bone density was evaluated by measuring Hounsfield Units in panoramic and cross sections obtained by digital scanner. Statistycal analysis by Kolmogorov-Smirnov test was performed for ELISA data. Bone density was analyzed by Shapiro-Wilk test. Subsequently t test was applied. P<0.05 was considered to be significant. Results: The concentration of interleukin-6 increased with the application of melatonin without statistically significance (361.32 ± 235.22 pg/ml vs 262.58 ± 233.92 pg/ml). Nitrotyrosine concentrations showed values below to the detectability pattern (<0.001 nM) in Optic Density curve. Bone density in panoramic sections at socket after melatonin application showed no significant difference (561.98 ± 105.92 HU vs 598.82 ± 209.03 HU). In cross sections, bone density in the alveolar region showed no significant difference(377.42 ± 125.67 HU vs 347.56 ± 97.02 HU). Conclusions: Within the limitations of this pilot study, no differences with the application of melatonin were found in terms of the concentration of interleukin-6 and bone density in post-extraction socket of retained mandibular third molars. Key words:Melatonin, inflammation, pain, bone density, third molar surgery. PMID:25350595

Fernández-Tresguerres, Isabel; Ortega-Aranegui, Ricardo; López-Quiles, Juan

2014-01-01

315

An Innovative Approach for Management of Vertical Coronal Fracture in Molar: Case Report  

PubMed Central

Unlike anterior teeth, acute exogenous trauma is an infrequent cause of posterior coronal vertical tooth fractures. Endodontic and restorative management of such fractures is a great challenge for the clinician. Newer advancements in adhesive techniques can provide successful intracoronal splinting of such teeth to reinforce the remaining tooth structure. This paper describes the diagnosis and management of a case of complicated vertical coronal fracture in mandibular first molar induced by a traffic accident. PMID:22567453

Kathuria, Ambica; Kavitha, M.; Ravishankar, P.

2012-01-01

316

Prevalence and Bilateral Occurrence of First Permanent Molar Caries in 12-Year-Old Students  

PubMed Central

Background and aims Dental caries is one of the most prevalent chronic diseases in children and DMFT index is the most important quantitative factor for measuring tooth health. The purpose of the present study was to determine prevalence and bilateral occurrence of first permanent molar caries in 12-year-old Iranian students. Materials and methods This cross-sectional study was carried out on 563 twelve-year-old stu-dents (307 boys and 256 girls), randomly selected from private and public schools of Rafsanjan, Iran, in 2006. All students were examined clinically for dental caries using the World Health Organization (WHO) criteria by a specialist on a dental chair in Rafsanjan Dental School. Data was analyzed using chi-square and t-test. Results The mean DMFT score of first permanent molars was 1.9 ± 1.6 (1.83 boys, 1.98 girls) and 31.4% (32.9% boys, 29.7% girls) of the students were caries free. There were no significant differences between boys and girls. Decayed (D) component yielded to be 40.9%, missing (M) 0.35% and filled (F) 6.22%. Maxillary and mandibular first permanent molars had 80.8% and 84% bilateral caries occurrence, respectively. There were no significant differences between the caries prevalence of right and left sides. Conclusion Caries prevalence among 12-year-old students in Rafsanjan, Iran is less than the global standards of WHO and FDI for 2000, but close to the gold standard for 2010. Bilateral caries occurrence in the first permanent molars was concluded to be high in the study population. PMID:23277840

Sadeghi, Mostafa

2007-01-01

317

Electrical Conductance of Fissure Enamel in Recently Erupted Molar Teeth as Related to Caries Status  

Microsoft Academic Search

Pit-and-fissure caries lesions contribute greatly to the caries incidence in permanent molar teeth in children. To date, the diagnosis of occlusal caries is still performed mainly by visual inspection, periodically aided by bite-wing radiography. However, in detecting small occlusal carious lesions, these methods perform inadequately, especially in low caries prevalence populations or individuals. The use of electrical conductance measurements (ECMs)

Y. L. Ie; E. H. A. M. Verdonschot; M. J. M. Schaeken; M. A. van’t Hof

1995-01-01

318

Evaluation of chronological age based on third molar development in the Spanish population  

Microsoft Academic Search

A cross-sectional study was carried out to assess chronological age estimation based on the stages of third lower molar development, following the eight stages (A–H) method of Demirjian et al. The final sample consisted of 1,054 orthopantomograms from Spanish individuals of known chronological age (range 14–21 years) and gender (462 males and 592 females). Results showed a stronger correlation for

José L. Prieto; Elena Barbería; Ricardo Ortega; Concepción Magaña

2005-01-01

319

Measurement and correlation of excess molar enthalpy at various temperatures acetonitrile + diethylamine or s -butylamine mixtures  

Microsoft Academic Search

Summary As a continuation of our studies on excess functions of binary systems containing acetonitrile-amines mixtures, in this work excess molar enthalpy (HmE) of acetonitrile+diethylamine or s-butylamine mixtures have been determined as a function of composition at 288.15, 293.15, 298.15 and 303.15 K at atmospheric pressure using a modified 1455 Parr adiabatic calorimeter. The excess enthalpy data are positive for

R. F. Checoni; A. Z. Francesconi

2005-01-01

320

Bone sialoprotein-induced reparative dentinogenesis in the pulp of rat’s molar  

Microsoft Academic Search

Bone sialoprotein (BSP), an osteogenic protein (OP), mixed with a carrier, was implanted in the pulp of rat first upper molars\\u000a (OP group). Cavities were prepared with dental burs and pulp perforation was carried out by pressure with the tip of a steel\\u000a probe. After 8, 14, and 30 days, the rats were killed and the pulps of the OP

F. Decup; B. Palmier; D. Buch; J. J. Lasfargues; E Salih; M. Goldberg

2000-01-01

321

Mean-square optical anisotropies and molar Kerr constants of cyclic and linear dimethyl siloxanes  

Microsoft Academic Search

Mean-square optical anisotropies, ??2?0, and mean molar Kerr constants, ?mK?0, have been calculated for cyclic dimethyl siloxane oligomers having from n=8 to n=20 skeletal bonds. Stringent criteria were used to select ‘‘cyclic’’ conformations of the equivalent open chains based on the relative orientations and rotational states of the terminal bonds. The values obtained for the cyclic oligomers are compared with

Stephen J. Mumby; Martin S. Beevers

1985-01-01

322

Indications and Risk Factors for Complications of Lower Third Molar Surgery in a Nigerian Teaching Hospital  

PubMed Central

Background: The surgical extraction of impacted third molars is a common oral surgical procedure, and it is often associated with complications such as sensory nerve damage, dry socket, pain, swelling, trismus, infection and hemorrhage. Aim: The aim of this study was to determine the surgical indications and risk factors for complications of third molar surgery at a Nigerian teaching hospital. Materials and Methods: Medical records of patients referred to the Oral Surgery Clinic of our institution for surgical extraction of their impacted mandibular third molars from January 2008 to December 2010 were retrospectively examined. Information on patients’ demography, types of impaction, operative parameters and complications were obtained and analyzed using Statistical Package for Social Sciences (SPSS Version 13), Chicago, IL, USA. A P < 0.0.5 was considered significant. Results: A total of 330 impacted teeth were extracted from 250 patients. Male comprises (104/250 [41.6%]) and female (146/250 [58.4%]). The mesioangular (176/330 [53.4%]) and distoangular (73/330 [22.1%]) impactions were the commonest types. Recurrent pericoronitis (154/330 [46.7%]) was the most common indication for extraction. The complications were delayed healing (19/330 [5.8%]), alveolar, osteitis (9/330 [2.7%]) and injury to alveolar nerve (2/330 [0.6%]). Cigarette smoking (P < 0.001), Oral contraceptives use (P = 0.01), age of the patient (P = 0.03) and the surgeon's experience (P = 0.04) were found to be significantly associated with the development of alveolar osteitis; nerves injuries were significantly associated with the raising of a lingual flap (P < 0.001) and the technique of surgery (P ? 0.001). Conclusion: The age of the patient, cigarette smoking and oral contraceptive use at the time of surgery are some of the factors affecting outcome in third molar surgery. PMID:25506490

Osunde, OD; Saheeb, BD; Bassey, GO

2014-01-01

323

Near-UV molar absorptivities of alachlor, mecroprop-p, pendimethalin, propanil and trifluralin in methanol  

Microsoft Academic Search

An experimental set-up consisting of two parallel absorption cells coupled to a CCD detector was used to determine absolute values of molar absorptivity coefficients ? of five herbicides (alachlor, mecoprop-p, pendimethalin, propanil and trifluralin) in methanol. The absorption spectra were measured using a deuterium lamp at room temperature (298±2K) over the wavelength range 240–340nm, except for pendimethalin and trifluralin where

Eneida Reyes Perez; Stéphane Le Calvé; Philippe Mirabel

2008-01-01

324

Classifying stages of third molar development: crown length as a predictor for the mature root length.  

PubMed

Multiple tooth development staging techniques were reported based on arbitrarily set borderlines between succeeding stages. Anatomic tooth features or predictions of future tooth part dimensions were described to identify the thresholds between the established stages. The need to predict mature tooth dimensions, while the tooth considered is still in development, is a drawback to use this staging technique for dental age estimations. Using the fully mature crown length as a predictor for the future root length could provide a tool for undisputable staging. The aim of this study was first to measure the crown and root length of fully mature third molars and second to investigate whether the crown length could be used as a predictor of the root length, in order to classify the observed root length as a proportion of the future mature root. The crown and root lengths of all present third molars were digitally measured on dental panoramic radiographs of 1,000 subjects. The included subjects were equally distributed in gender, and their age ranged between 22 and 40 years. Two occlusal borders, the cement enamel junction and the root apices, were defined as landmarks for standardized measurements. Regression models with root length as response and crown length as predictor were established and revealed low R (2) and high RMSE values. Due to the small explained variance by the prediction models and the high variation in prediction errors, the observed crown length cannot be used to predict the final root length of a developing third molar. PMID:24801360

Altalie, Salem; Thevissen, Patrick; Willems, Guy

2015-01-01

325

Effects of early unilateral mandibular first molar extraction on condylar and ramal vertical asymmetry  

PubMed Central

Objective: The objective of the following study is to investigate the mandibular vertical asymmetry in a group of patients with early unilateral mandibular first molar extractions. Materials and Methods: Mandibular asymmetry index measurements (condylar, ramal and condylar-plus-ramal) were performed on the panoramic radiographs of a study group including 51 patients (mean age: 18.60 ± 1.11 years) and a control group of 51 patients (mean age: 18.53 ± 1.29 years). Group I included patients with a unilateral mandibular first molar extracted before the age of 12 years. Group II included patients with no extractions and had excellent Class I relationships, no missing teeth and slight or moderate anterior crowding. A paired t-test was used to determine possible statistically significant differences between the sides for the measurements. Student's t-test was used for the comparison of asymmetry index values between the groups and genders. Results: No group showed statistically significant sex-or side-specific differences for posterior vertical height measurements. Condylar asymmetry index and ramal asymmetry index measurements were not statistically different between the groups, while condylar-plus-ramal asymmetry index (CRAI) measurements were statistically different between the groups (P = 0.019). Conclusions: A slight difference for CRAI value was found in patients with early unilateral mandibular first molar extractions. PMID:24966767

Halicioglu, Koray; Celikoglu, Mevlut; Buyuk, Suleyman K.; Sekerci, Ahmet E.; Candirli, Celal

2014-01-01

326

Gross enamel hypoplasia in molars from subadults in a 16th-18th century London graveyard.  

PubMed

Dental Enamel Hypoplasia has long been used as a common nonspecific stress indicator in teeth from archaeological samples. Most researchers report relatively minor linear and pitted hypoplastic defects on tooth crown surfaces. In this work we report a high prevalence and early age of onset of extensive enamel defects in deciduous and permanent molars in the subadults from the post-medieval cemetery of Broadgate, east central London. Analysis of the dentition of all 45 subadults from the cemetery, using both macroscopic and microscopic methods, reveals disturbed cusp patterns and pitted, abnormal and arrested enamel formation. Forty-one individuals from this group (93.2%) showed some evidence of enamel hypoplasia, 28 of them showing moderate or extensive lesions of molars, deciduous or permanent (63.6% of the sample). Scanning Electron Microscope images reveal many molars with grossly deformed cuspal architecture, multiple extra cusps and large areas of exposed Tomes' process pits, where the ameloblasts have abruptly ceased matrix production, well before normal completion. This indented, rough and poorly mineralized surface facilitates both bacterial adhesion and tooth wear, and when such teeth erupt fully into the mouth they are likely to wear and decay rapidly. We suggest that this complex combination of pitted and plane-form lesions, combined with disruption of cusp pattern and the formation of multiple small cusps, should henceforth be identified as "Cuspal Enamel Hypoplasia." PMID:17492667

Ogden, A R; Pinhasi, R; White, W J

2007-07-01

327

Molar mass of silicon highly enriched in 28Si determined by IDMS  

NASA Astrophysics Data System (ADS)

The molar mass of a new silicon crystal material highly enriched in 28Si ('Si28', x(28Si) >99.99%) has been measured for the first time using a combination of a modified isotope dilution mass spectrometry (IDMS) technique and a high resolution multicollector-ICP-mass spectrometer. This work is related to the redetermination of the Avogadro constant NA with an intended relative measurement uncertainty urel(NA) <= 2 × 10-8. The corresponding experimental investigations of the International Avogadro Coordination (IAC) were performed using this novel 'Si28' material. One prerequisite of the redetermination of NA is the determination of the isotopic composition and thus molar mass of 'Si28' with urel(M('Si28')) <= 1 × 10-8. At PTB, a molar mass M('Si28') = 27.976 970 27(23) g mol-1 has been determined with an associated relative uncertainty urel(M('Si28')) = 8.2 × 10-9, opening the opportunity to reach the target uncertainty of NA.

Pramann, Axel; Rienitz, Olaf; Schiel, Detlef; Schlote, Jan; Güttler, Bernd; Valkiers, Staf

2011-04-01

328

Inferior Alveolar Nerve Injury after Mandibular Third Molar Extraction: a Literature Review  

PubMed Central

ABSTRACT Objectives The purpose of this study was to systematically review the comprehensive overview of literature data about injury to the inferior alveolar nerve after lower third molar extraction to discover the prevalence of injury, the risk factors, recovery rates, and alternative methods of treatment. Material and Methods Literature was selected through a search of PubMed electronic databases. Articles from January 2009 to June 2014 were searched. English language articles with a minimum of 6 months patient follow-up and injury analysis by patient’s reporting, radiographic, and neurosensory testing were selected. Results In total, 84 literature sources were reviewed, and 14 of the most relevant articles that are suitable to the criteria were selected. Articles were analyzed on men and women. The influence of lower third molar extraction (especially impacted) on the inferior alveolar nerve was clearly seen. Conclusions The incidence of injury to the inferior alveolar nerve after lower third molar extraction was about 0.35 - 8.4%. The injury of the inferior alveolar nerve can be predicted by various radiological signs. There are few risk factors that may increase the risk of injury to the nerve such as patients over the age of 24 years old, with horizontal impactions, and extraction by trainee surgeons. Recovery is preferable and permanent injury is very rare. PMID:25635208

Juodzbalys, Gintaras

2014-01-01

329

Accuracy of the Dentaport ZX apex locator for working length determination when retreating molar root canals.  

PubMed

The aim of this study was to evaluate the accuracy of the Dentaport ZX apex locator for working length determination during root canal retreatment of mandibular molars. Fifteen extracted mandibular first molars with separate mesial canals and apical foraminae and one distal canal were selected. The mesiobuccal and distal canals were investigated; the length with the file tip at the major diameter was defined as the tooth length (TL). The canals were prepared with ProTaper files to 1 mm short of this and filled with gutta-percha and AH Plus sealer. One week later, the root fillings were removed using ProTaper retreatment files. Tooth length was remeasured and recorded as the retreatment tooth length (RTL). Then electronic measurements were taken at the major (electronic apex locator (EAL) major) and minor (EAL minor) foraminae as suggested by the instrument display. These lengths were compared with RTL and measurements 0.5 and 1 mm short of this distance. For both canals, no significant difference was found between RTL and EAL major, and 0.5 mm short of RTL and EAL minor (P > 0.05). There were significant differences found between all other readings. The Dentaport ZX could not detect the minor foramen accurately but was able to indicate the major foramen in molars undergoing a root canal retreatment procedure. PMID:24697957

Cimilli, Hale; Aydemir, Seda; Arican, Burcin; Mumcu, Gonca; Chandler, Nicholas; Kartal, Nevin

2014-04-01

330

Root and Canal Morphology of Mandibular Second Molar in an Iranian Population by Clearing Method  

PubMed Central

Statement of Problem: The knowledge of the pulp anatomy plays an important role in the success of endodontic treatments. Purpose: The aim of this study was to determine the root and canal morphology of the mandibular second molar teeth in an Iranian population. Material and Methods: One hundred intact human mandibular second molars were collected. The teeth were examined visually and the number of their roots were recorded. The teeth were covered using of lacquer. Access cavities were prepared and the pulp tissue was dissolved by sodium hypochlorite. The apices were covered with the glue and the root canals were injected with the methylene blue and were decalcified with 10% nitric acid, dehydrated with ascending concentrations of alcohol and rendered clear by immersion in methyl salicylate. The following remarks were evaluated: (i) number of root canals per tooth; (ii) number of canals per root; (iii) canal configuration in each root. Results: Of 100 examined teeth; 6% had one root, 89% had two roots, 2% had three roots and 3% had C-shaped roots. The teeth were classified based on the number of canals: 3 % had single canal, 6 % two canals, 54% three canals, 34% four canals, whilst 3 % had C-shaped roots. Based on the Vertucci classification, the most prevalent canal configuration in the mesial root was type II and in the distal root was type I. Conclusion : Iranian mandibular second molar teeth exhibit features which are similar to the average Jordanian, Caucasian and Burmese root and canal morphology. PMID:24724124

Zare Jahromi, M; Jafari Golestan, F; Mashhadi Esmaeil, M; MoouaviZahed, SH; Sarami, M

2013-01-01

331

Impacted lower third molars: Can preoperative salivary pH influence postoperative pain?  

PubMed Central

Aim The literature focuses little attention on factors that influence third molar post extraction pain (PEP). One factor that may play a role in PEP is saliva. We undertook a study in patients subjected to third molar extraction with the aim of assessing the influence of salivary pH on PEP. Materials and Methods: Thirty-one healthy patients with one impacted inferior lower third molar with mean age of 21.02 ± 2.05 years, underwent surgery for similar impactions. The process of pH measuring was carried out without delay after saliva collection, with a combination electrode connected to a PHM 62 pH meter. Pain assessment was done at 4, 8, 12, 18 and 24 hours on the first day. The scale ranged from 0 to 10 in which 0 and 10 denoted ‘no pain’ and ‘maximum pain,’ respectively. Results: The multivariate analysis suggests that the factors that influence pain are patients’ sex (B = - 0.466) and the saliva pH (B = - 1.093). According to the findings of our study, PEP intensity is assumed to have a reverse correlation with salivary pH and is also assumed to be greater in females. Conclusion: Due to the fact that no previous study has indicated such findings so far, further studies are needed to assess the importance of preoperative pH value and its clinical significance on the level of PEP. PMID:22442582

Jafari, Seyed Mehdi; Motamedi, Mohammad Hosein Kalantar; Jafari, Mehrdad; Tabeshfar, Shervin; Jafari, Mehryar; Naghizadeh, Mohammad Mehdi

2010-01-01

332

Laparoscopic partial splenic resection.  

PubMed

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. PMID:7773460

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

1995-04-01

333

Partially-Filled Valley  

NASA Technical Reports Server (NTRS)

30 March 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a valley which has become partially-filled with material. It is located west of Hellas Planitia. The valley, entering the scene from the east (right), turns toward the southwest (lower left) and splits to form a 'V'. Partially-filled depressions are common throughout the scene, including the circular feature near the top of the image. In each such case, the filling material is probably the remains of a material that once covered the entire scene.

Location near: 48.4oS, 318.1oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

2006-01-01

334

Applications of partially quenched chiral perturbation theory  

SciTech Connect

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}

Golterman, M.F.; Leung, K.C. [Department of Physics, Washington University, St. Louis, Missouri63130 (United States)] [Department of Physics, Washington University, St. Louis, Missouri63130 (United States)

1998-05-01

335

Does the Relationship between Retained Mandibular Third Molar and Mandibular Angle Fracture Exist? An Assessment of Three Possible Causes  

PubMed Central

The objective of this study is to discuss problems associated with dental retention through three clinical cases of mandible fractures related to the presence of retained lower third molars, emphasizing the possibility of mandible fractures resulting from this or from the extraction procedure. The three evaluated patients had a fracture in the mandible angle. The third molars were present in all the cases, as was the relationship of the fracture with the teeth. After evaluating the three cases and reviewing literature, it is believed that the presence of the retained lower third molars and the surgical procedures for their extraction increase the risk of mandible angle fractures. PMID:23997857

Duarte, Bruno G.; Assis, Diogo; Ribeiro-Júnior, Paulo; Gonçales, Eduardo Sanches

2012-01-01

336

Diagnostic CBCT in Dentigerous Cyst with Ectopic Third Molar in the Maxillary Sinus-A Case Report.  

PubMed

Dentigerous cyst is the second most common odontogenic cyst after radicular cyst. This report describes a case of a dentigerous cyst associated with an impacted maxillary third molar. Patient presented with foul smelling discharge through nose and oral cavity. Cone beam computed tomography revealed maxillary third molar displaced to lateral wall of the nose and a unilocular radiolucency obliterating the entire maxillary sinus. A provisional diagnosis of infected dentigerous cyst was made. The cyst was enucleated along with removal of third molar. Histopathological examination confirmed the diagnosis of dentigerous cyst. The patient recovery was uneventful. PMID:25121067

N S, Mamatha; Krishnamoorthy, Bhuvana; J K, Savitha; Bhai, Pankaja

2014-06-01

337

A Prescription for Partial Synchrony  

E-print Network

Algorithms in message-passing distributed systems often require partial synchrony to tolerate crash failures. Informally, partial synchrony refers to systems where timing bounds on communication and computation may exist, but the knowledge...

Sastry, Srikanth

2012-07-16

338

Laparoscopic partial splenectomy  

Microsoft Academic Search

Background  The immunologic function of the spleen and its important role in immune defense has led to splenic-preserving surgery. This\\u000a study aimed to evaluate whether laparoscopic partial splenectomy is safe.\\u000a \\u000a \\u000a \\u000a Methods  Data on consecutive patients presenting with localized benign or malignant disease of the spleen were included in a prospective\\u000a database. The surgical technique consisted of six steps: patient positioning and trocar

S. Uranues; D. Grossman; L. Ludwig; R. Bergamaschi

2007-01-01

339

[Arthroscopic partial meniscectomy].  

PubMed

Partial closed meniscectomy under arthroscopic control is feasible in bucket handle tears and in some cases of L-shaped or longitudinal meniscal lesions. The operation is performed in general anesthesia but without hospitalization of the patient. Postoperative morbidity in 18 patients was surprisingly low, 16 patients being without disturbances two weeks after surgery. Mean duration of working inability was 6.5 days. For the experienced arthroscopist, low costs and decreased morbidity compared to arthrotomy recommend this procedure in selected cases of meniscal lesions. PMID:7440187

Glinz, W

1980-06-01

340

Comparative Evaluation of Vital Parameters During Third Molar Surgery Under Local Anaesthesia with and without Sedative Agents  

PubMed Central

Aims: To compare vital parameters; operator’s comfort; and patient’s satisfaction during impacted third molar removal under local anaesthesia, with or without sedative agents. Materials and Methods: Ninety patients undergoing elective third molar surgery were randomly divided into three groups of 30 each: Group A received propofol along with local anaesthesia; Group B received midazolam along with local anaesthesia and Group C received local anaesthesia alone. After the local anaesthesia, with or without sedative agents, the impacted third molars were removed in Operation Theater. Results: Group A clearly showed advantages over Group B & C on all the parameters that we have selected. Conclusion: Even though the cost of propofol is high, suitable operating conditions, faster onset of sedation, rapid recovery, and minimal side effects support the use of this drug for conscious sedation for third molar surgery.

Kshisagar, Rajesh A; Dhuvad, Mukesh M

2014-01-01

341

Solubility and Excess Molar Properties of 1,3-Dimethylimidazolium Methylsulfate, or 1Butyl3-Methylimidazolium Methylsulfate, or 1Butyl3-Methylimidazolium Octylsulfate Ionic Liquids with n Alkanes and Alcohols: Analysis in Terms of the PFP and FBT Models 1  

Microsoft Academic Search

The solubility of 1-butyl-3-methylimidazolium octylsulfate, [BMIM][OcSO4], has been determined in hydrocarbon (n-hexane, n-heptane, n-octane or n-decane) solutions and alcohol (methanol, 1-butanol, 1-hexanol, 1-octanol or 1-decanol) solutions. Densities and excess molar\\u000a volumes, V\\u000a E\\u000a m, have been determined for 1-methyl-3-methylimidazolium methylsulfate, [MMIM][CH3SO4], solutions with an alcohol (methanol, ethanol or 1-butanol) and with water; for 1-butyl-3-methylimidazolium methylsulfate,\\u000a [BMIM][CH3SO4], with an alcohol (methanol,

U. Doma?ska; A. Pobudkowska; A. Wi?niewska

2006-01-01

342

Considerations of mandibular angle fractures during and after surgery for removal of third molars: a review of the literature  

Microsoft Academic Search

Background  Angle fractures are quite common considering that the angle of the mandible forms an area of lower resistance which contains\\u000a a thicker upper border, a thin basilar bone, and the presence of an impacted mandibular third molar. Common complications\\u000a of mandibular third molar surgery include alveolar osteitis (dry socket), secondary infection, nerve dysfunction, and hemorrhage.\\u000a Reports of mandibular fracture during

Bruno Ramos Chrcanovic; Antônio Luís Neto Custódio

2010-01-01

343

Interglobular dentine in first and third molars: Relation to hours of sunshine during growth in two archeological populations from England  

Microsoft Academic Search

Summary  Thin ground sections of first molars (M1), third molars (M3), and second premolars (P2) were scanned by light microscopy for\\u000a relative amounts of interglobular dentine (IGD) in the top half of the crown. Two well-dated cemetery series of English provenance\\u000a were sampled: the Saint Bride's Church collection (SB) from eighteenth century London, for which the sex, age, and calendar\\u000a year

Francis Ivanhoe

1982-01-01

344

Compositional dependence of molar absorptivities of near-infrared OH and H 2O bands in rhyolitic to basaltic glasses  

Microsoft Academic Search

Molar absorption coefficients (molar absorptivities) of the near infrared combination bands at 4500 and 5200 cm?1 assigned to OH groups and H2O molecules, respectively, were determined for glasses of dacitic, andesitic and basaltic compositions. Total water contents (range 1.5–6.3 wt.%) of the samples used in the calibration were determined by pyrolysis and subsequent Karl–Fischer Titration. Different combinations of baseline types

Susanne Ohlhorst; Harald Behrens; François Holtz

2001-01-01

345

Changing the root morphology in a case of periodontal impairment at a maxillary molar used as a sustaining tooth.  

PubMed

Research evolution regarding dental research determines the increase of patient's desire to preserve their dentition for a long time. The loss of a molar tooth as the last teeth present on the dental arch, raises issues regarding how the prosthesis should be placed, still patients are usually reluctant to use as last resort the prosthetic solution. This article describes the technique of root amputation to save a maxillary molar used as bridge abutments. PMID:25329127

D?guci, Constantin; D?guci, Lumini?a; B?t?iosu, Marilena; Popescu, Mihai Raul; Bunget, Adina; M?rg?rit, Ruxandra; Andrei, Oana Cella; Dumitrache, Adina; Vasile, Nicolae; Sfeatcu, Ruxandra

2014-01-01

346

Unique inhibitory cascade pattern of molars in canids contributing to their potential to evolutionary plasticity of diet  

PubMed Central

Developmental origins that guide the evolution of dental morphology and dental formulae are fundamental subjects in mammalian evolution. In a previous study, a developmental model termed the inhibitory cascade model was established. This model could explain variations in relative molar sizes and loss of the lower third molars, which sometimes reflect diet, in murine rodents and other mammals. Here, I investigated the pattern of relative molar sizes (inhibitory cascade pattern) in canids, a taxon exhibiting a wide range of dietary habits. I found that interspecific variation in canid molars suggests a unique inhibitory cascade pattern that differs from that in murine rodents and other previously reported mammals, and that this variation reflects dietary habits. This unique variability in molars was also observed in individual variation in canid species. According to these observations, canid species have greater variability in the relative sizes of first molars (carnassials), which are functionally important for dietary adaptation in the Carnivora. In conclusion, an inhibitory cascade that differs from that in murine rodents and other mammals may have contributed to diverse dietary patterns and to their parallel evolution in canids. PMID:23467478

Asahara, Masakazu

2013-01-01

347

Comparative studies between mice molars and incisors are required to draw an overview of enamel structural complexity  

PubMed Central

In the field of dentistry, the murine incisor has long been considered as an outstanding model to study amelogenesis. However, it clearly appears that enamel from wild type mouse incisors and molars presents several structural differences. In incisor, exclusively radial enamel is observed. In molars, enamel displays a high level of complexity since the inner part is lamellar whereas the outer enamel shows radial and tangential structures. Recently, the serotonin 2B receptor (5-HT2BR) was shown to be involved in ameloblast function and enamel mineralization. The incisors from 5HT2BR knockout (KO) mice exhibit mineralization defects mostly in the outer maturation zone and porous matrix network in the inner zone. In the molars, the mutation affects both secretory and maturation stages of amelogenesis since pronounced alterations concern overall enamel structures. Molars from 5HT2BR KO mice display reduction in enamel thickness, alterations of inner enamel architecture including defects in Hunter-Schreger Bands arrangements, and altered maturation of the outer radial enamel. Differences of enamel structure were also observed between incisor and molar from other KO mice depleted for genes encoding enamel extracellular matrix proteins. Thus, upon mutation, enamel analysis based exclusively on incisor defects would be biased. In view of the functional relationship between enamel structure and tooth morphogenesis, identification of molecular actors involved in amelogenesis requires comparative studies between mice molars and incisors. PMID:25285079

Goldberg, Michel; Kellermann, O.; Dimitrova-Nakov, S.; Harichane, Y.; Baudry, A.

2014-01-01

348

Studies on the phase diagram of Pb-Fe-O system and standard molar Gibbs energy of formation of 'PbFe5O8.5' and Pb2Fe2O5  

NASA Astrophysics Data System (ADS)

Partial phase diagram of Pb-Fe-O system has been established by phase equilibration studies over a wide temperature range coupled with high temperature solid electrolyte based emf cells. Ternary oxides are found to coexist with liquid lead only at temperatures above 900 K. At temperatures below 900 K, iron oxides coexist with liquid lead. Standard molar Gibbs energy of formation of ternary oxides 'PbFe5O8.5' and Pb2Fe2O5 were determined by measuring equilibrium oxygen partial pressures over relevant phase fields using emf cells and are given by the following expressions: ?fGmo 'PbFeO'±1.0(kJ mol)=-2208.1+0.6677(T/K) (917?T/K?1117) ?fGmo PbFeO±0.8(kJ mol)=-1178.4+0.3724(T/K) (1050?T/K?1131) .

Sahu, Sulata Kumari; Ganesan, Rajesh; Gnanasekaran, T.

2012-07-01

349

Construction of a cDNA library for miniature pig mandibular deciduous molars  

PubMed Central

Background The miniature pig provides an excellent experimental model for tooth morphogenesis because its diphyodont and heterodont dentition resembles that of humans. However, little information is available on the process of tooth development or the exact molecular mechanisms controlling tooth development in miniature pigs or humans. Thus, the analysis of gene expression related to each stage of tooth development is very important. Results In our study, after serial sections were made, the development of the crown of the miniature pigs’ mandibular deciduous molar could be divided into five main phases: dental lamina stage (E33-E35), bud stage (E35-E40), cap stage (E40-E50), early bell stage (E50-E60), and late bell stage (E60-E65). Total RNA was isolated from the tooth germ of miniature pig embryos at E35, E45, E50, and E60, and a cDNA library was constructed. Then, we identified cDNA sequences on a large scale screen for cDNA profiles in the developing mandibular deciduous molars (E35, E45, E50, and E60) of miniature pigs using Illumina Solexa deep sequencing. Microarray assay was used to detect the expression of genes. Lastly, through Unigene sequence analysis and cDNA expression pattern analysis at E45 and E60, we found that 12 up-regulated and 15 down-regulated genes during the four periods are highly conserved genes homologous with known Homo sapiens genes. Furthermore, there were 6 down-regulated and 2 up-regulated genes in the miniature pig that were highly homologous to Homo sapiens genes compared with those in the mouse. Conclusion Our results not only identify the specific transcriptome and cDNA profile in developing mandibular deciduous molars of the miniature pig, but also provide useful information for investigating the molecular mechanism of tooth development in the miniature pig. PMID:24750690

2014-01-01

350

Treatment outcome and efficacy of an aligner technique – regarding incisor torque, premolar derotation and molar distalization  

PubMed Central

Background The aim of this study was to investigate the efficacy of orthodontic treatment using the Invisalign® system. Particularly, we analyzed the influence of auxiliaries (Attachment/Power Ridge) as well as the staging (movement per aligner) on treatment efficacy. Methods We reviewed the tooth movements of 30 consecutive patients who required orthodontic treatment with Invisalign®. In all patients, one of the following tooth movements was performed: (1) Incisor Torque >10°, (2) Premolar derotation >10° (3) Molar distalization >1.5 mm. The groups (1)-(3) were subdivided: in the first subgroup (a) the movements were supported with the use of an attachment, while in the subgroup (b) no auxiliaries were used (except incisor torque, in which Power Ridges were used). All tooth movements were performed in a split-mouth design. To analyze the clinical efficacy, pre-treatment and final plaster cast models were laser-scanned and the achieved tooth movement was determined by way of a surface/surface matching algorithm. The results were compared with the amount of tooth movement predicted by ClinCheck®. Results The overall mean efficacy was 59% (SD?=?0.2). The mean accuracy for upper incisor torque was 42% (SD?=?0.2). Premolar derotation showed the lowest accuracy with approximately 40% (SD?=?0.3). Distalization of an upper molar was the most effective movement, with efficacy approximately 87% (SD?=?0.2). Conclusion Incisor torque, premolar derotation and molar distalization can be performed using Invisalign® aligners. The staging (movement/aligner) and the total amount of planned movement have an significant impact on treatment efficacy. PMID:24923279

2014-01-01

351

Function of pretribosphenic and tribosphenic mammalian molars inferred from 3D animation.  

PubMed

Appearance of the tribosphenic molar in the Late Jurassic (160 Ma) is a crucial innovation for food processing in mammalian evolution. This molar type is characterized by a protocone, a talonid basin and a two-phased chewing cycle, all of which are apomorphic. In this functional study on the teeth of Late Jurassic Dryolestes leiriensis and the living marsupial Monodelphis domestica, we demonstrate that pretribosphenic and tribosphenic molars show fundamental differences of food reduction strategies, representing a shift in dental function during the transition of tribosphenic mammals. By using the Occlusal Fingerprint Analyser (OFA), we simulated the chewing motions of the pretribosphenic Dryolestes that represents an evolutionary precursor condition to such tribosphenic mammals as Monodelphis. Animation of chewing path and detection of collisional contacts between virtual models of teeth suggests that Dryolestes differs from the classical two-phased chewing movement of tribosphenidans, due to the narrowing of the interdental space in cervical (crown-root transition) direction, the inclination angle of the hypoflexid groove, and the unicuspid talonid. The pretribosphenic chewing cycle is equivalent to phase I of the tribosphenic chewing cycle, but the former lacks phase II of the tribosphenic chewing. The new approach can analyze the chewing cycle of the jaw by using polygonal 3D models of tooth surfaces, in a way that is complementary to the electromyography and strain gauge studies of muscle function of living animals. The technique allows alignment and scaling of isolated fossil teeth and utilizes the wear facet orientation and striation of the teeth to reconstruct the chewing path of extinct mammals. PMID:25091547

Schultz, Julia A; Martin, Thomas

2014-10-01

352

Absolute silicon molar mass measurements, the Avogadro constant and the redefinition of the kilogram  

NASA Astrophysics Data System (ADS)

The results of an absolute silicon molar mass determination of two independent sets of samples from the highly 28Si-enriched crystal (AVO28) produced by the International Avogadro Coordination are presented and compared with results published by the Physikalisch-Technische Bundesanstalt (PTB, Germany), the National Research Council (NRC, Canada) and the National Metrology Institute of Japan (NMIJ, Japan). This study developed and describes significant changes to the published protocols for producing absolute silicon isotope ratios. The measurements were made at very high resolution on a multi-collector inductively coupled plasma mass spectrometer using tetramethylammonium hydroxide (TMAH) to dissolve and dilute all samples. The various changes in the measurement protocol and the use of TMAH resulted in significant improvements to the silicon isotope ratio precision over previously reported measurements and in particular, the robustness of the 29Si/30Si ratio of the AVO28 material. These new results suggest that a limited isotopic variability is present in the AVO28 material. The presence of this variability is at present singular and therefore its significance is not well understood. Fortunately, its magnitude is small enough so as to have an insignificant effect on the overall uncertainty of an Avogadro constant derived from the average molar mass of all four AVO28 silicon samples measured in this study. The NIST results confirm the AVO28 molar mass values reported by PTB and NMIJ and confirm that the virtual element-isotope dilution mass spectrometry approach to calibrated absolute isotope ratio measurements developed by PTB is capable of very high precision as well as accuracy. The Avogadro constant NA and derived Planck constant h based on these measurements, together with their associated standard uncertainties, are 6.02214076(19) × 1023 mol-1 and 6.62607017(21) × 10-34 Js, respectively.

Vocke, R. D., Jr.; Rabb, S. A.; Turk, G. C.

2014-10-01

353

Microcomputed Tomography Analysis of Mesiobuccal Orifices and Major Apical Foramen in First Maxillary Molars  

PubMed Central

Objective: Aim of the study was to determined by microcomputed tomography (µCT) the horizontal distance between the main (MB1) and the second mesiobuccal canal (MB2) orifices, the vertical distance between the MB1 and MB2 orifices planes, and the distance between the anatomic apex and major apical foramen (AF). Furthermore, we characterized the entire internal and external anatomy of the MB, distalbuccal (DB) and palatal (P) maxillary first molars roots. Materials and Methods: Twenty-two intact extracted first maxillary molars were scanned by X-ray computed transaxial µCT and then 2D and 3D images were processed and analyzed. Results: The results showed that 77.27% of the mesiobuccal (MB) roots presented a second MB canal, and 29.41% of the MB2 were independent from the MB1 canals. In 15 teeth, there were three root canal orifices on the chamber floor, and 10 of these teeth presented MB2 canals. The mean vertical distance between the MB1 and MB2 planes was 1.68 ± 0.83 mm. Seven teeth had four orifices. The mean horizontal interorificial distance between the MB1 and MB2 orifices was 1.21 ± 0.5 mm. Accessory canals were observed in 33.33% of the roots, loops in 6.06%, while isthmuses were found in 15 of the 22 MB roots. Of the total roots, 74.24% presented one foramen, while all of the roots showed a major apical foramen that was not coincident with the anatomic apex. Conclusions: Our µCT analysis provided interesting features on the horizontal and vertical distance between the MB1 and MB2 orifices and on the distance of AF and anatomic apex. Clinical Relevance: These results have an important clinical value because might support the endodontist in the recruitment, negotiation and obturation of maxillary first molar canal system. PMID:22905069

Spagnuolo, Gianrico; Ametrano, Gianluca; D’Antò, Vincenzo; Formisano, Anna; Simeone, Michele; Riccitiello, Francesco; Amato, Massimo; Rengo, Sandro

2012-01-01

354

Enamel thickness variation of deciduous first and second upper molars in modern humans and Neanderthals.  

PubMed

Enamel thickness and dental tissue proportions have been recognized as effective taxonomic discriminators between Neanderthal and modern humans teeth. However, most of the research on this topic focused on permanent teeth, and little information is available for the deciduous dentition. Moreover, although worn teeth are more frequently found than unworn teeth, published data for worn teeth are scarce and methods for the assessment of their enamel thickness need to be developed. Here, we addressed this issue by studying the 2D average enamel thickness (AET) and 2D relative enamel thickness (RET) of Neanderthal and modern humans unworn to moderately worn upper first deciduous molars (dm(1)s) and upper second deciduous molars (dm(2)s). In particular, we used 3D ?CT data to investigate the mesial section for dm(1)s and both mesial and buccal sections for dm(2)s. Our results confirmed previous findings of an Neanderthal derived condition of thin enamel, and thinner enamel in dm(1)s than dm(2)s in both Neanderthal and modern humans. We demonstrated that the Neanderthal 2D RET indices are significantly lower than those of modern humans at similar wear stages in both dm(1)s and dm(2)s (p < 0.05). The discriminant analysis showed that using 2D RET from dm(1) and dm(2) sections at different wear stages up to 93% of the individuals are correctly classified. Moreover, we showed that the dm(2) buccal sections, although non-conventionally used, might have an advantage on mesial sections since they distinguish as well as mesial sections but tend to be less worn. Therefore, the 2D analysis of enamel thickness is suggested as a means for taxonomic discrimination between modern humans and Neanderthal unworn to moderately worn upper deciduous molars. PMID:25282273

Fornai, Cinzia; Benazzi, Stefano; Svoboda, Ji?í; Pap, Ildikó; Harvati, Katerina; Weber, Gerhard W

2014-11-01

355

What constitutes a clinically important pain reduction in patients after third molar surgery?  

PubMed Central

BACKGROUND: For patients with surgical third molar removal, it is unknown what constitutes a clinically important change in patients’ visual analogue scale (VAS) reports of pain intensity. OBJECTIVES: To determine what constitutes a clinically important change in pain intensity on a VAS following surgical removal of the third molar. METHODS: The study population consisted of patients participating in three randomized trials. Patients were asked to rate their pain three times per day over a period of seven days on a 100 mm VAS after surgical removal of the third molar. Global Perceived Effect was measured on day 1 and day 7 and was used as the external criterion for assessing clinically important pain reduction. Global Perceived Effect scores of 6 (‘much improved’) or higher were classified as clinically ‘successful’, and scores of 5 (‘slightly improved’) or below were classified as clinically ‘unsuccessful’. For each trial, the mean absolute and relative changes in VAS scores were calculated for both ‘successful’ and ‘unsuccessful’ treatments. Sensitivity and specificity analyses were performed. RESULTS: The patients who reported ‘successful’ pain reduction showed a relative pain reduction of ?69% and an absolute pain reduction >2.5 cm on the VAS, whereas patients who classified their pain reduction as ‘unsuccessful’ had a relative pain reduction of ?18.5% and an absolute pain reduction <0.5 cm on the VAS. Furthermore, sensitivity and specificity analyses showed that a cut-off point of ?50% relative pain reduction exhibited the best balance of sensitivity and specificity. CONCLUSION: Relative pain reduction of ?50% and an absolute pain reduction of ?2.5 cm on the VAS were most accurate in predicting a successful pain reduction after a given treatment. PMID:23957018

Martin, Wilhelmus JJM; Ashton-James, CE; Skorpil, NE; Heymans, MW; Forouzanfar, T

2013-01-01

356

Partial neutralization of a lupus anticoagulant by human immunoglobulin.  

PubMed

In a patient with a Lupus Anticoagulant (LA) and recurrent fetal loss, we observed a significant shortening of the APTT after high-dose intravenous immunoglobulin infusion (IVIg). The LA activity present in patient's serum and purified IgG was partially neutralized by IVIg in a dose-dependent way. In addition, IgG purified from IVIg and its F(ab')2 fragment neutralized LA activity of the patient's IgG. In both cases, the neutralization was dose-dependent and it was obtained with similar molar ratios. The "in vitro" neutralization of LA activity and the immediate shortening of the APTT after IVIg infusion, might be mediated through idiotype/antiidiotype interactions. On the other hand, the long-lasting effect of IVIg in this patient indicates that it may induce specific inhibition of autoantibody synthesis. We believe that IVIg should be considered as a therapeutic alternative for LA-related clinical disorders. PMID:2125757

Carreras, L O; Pérez, G N; Martinuzzo, M E; Malan-Borel, I; Malbrán, A; Said, P B

1990-08-13

357

Endodontic treatment of a mandibular first molar with three mesial canals and broken instrument removal.  

PubMed

To succeed in any dental procedure, the clinician's awareness of the patient's dental anatomy and its variations is crucial. In endodontic therapy, obtaining full information about the root canals' variations can affect the outcome substantially. This case report presents the endodontic treatment of a mandibular first molar exhibiting three mesial root canals with 4 mm of a separated K-file in the coronal third of the mesiolingual canal on an 18-year-old female patient. This case demonstrates the importance of locating additional canals in any roots undergoing endodontic treatment and how the clinician's awareness of aberrant internal anatomy may change the treatment results. PMID:20377564

Faramarzi, Farhad; Fakhri, Hamidreza; Fakri, Hamidreza; Javaheri, Homan H

2010-04-01

358

Fixed maxillary and mandibular zirconia implant frameworks milled with anatomically contoured molars: A clinical report.  

PubMed

Retrospective studies on restoring the patients with complete edentulism have reported a variety of complications, including the excessive wear and fracture of the acrylic resin teeth. Approaches to slow the process of wear include the use of porcelain teeth or altering the occlusal surface of acrylic resin teeth with amalgam or gold. Two 1-piece fixed zirconia implant frameworks masked with gingival porcelain and stained anatomically contoured first and second molars and individual ceramic crowns were used to restore both arches to optimum function and esthetics. This clinical report describes the steps for one method of providing the fixed prosthetic needs of the patients who is edentulous. PMID:25258262

Al-Mazedi, Mohammad; Razzoog, Michael E; Yaman, Peter

2014-11-01

359

The usefulness of Belgian formulae in third molar-based age assessment of Indians.  

PubMed

The third molars are one of few useful predictors for assessing the degree of maturity in adolescence and young adulthood. It has application in age estimation in the age group of 14-23 years, in general, and in juvenile/adult status prediction, in particular. Using a 10-stage grading of third molars, Gunst et al. developed regression formulae on a large sample of Belgians (n=2513) for estimating age. Their research has been recommended as a 'reference study' in age estimation guidelines. The present study has ventured to determine if estimating age in Indians using the Belgian formulae produced results comparable to those reported in the Belgian study; in addition, this study attempts to determine if the same formulae predicted juvenile/adult status (age molars. In total, 916 teeth were assessed using the same 10-stage grading. Age in each OPG was estimated by applying the relevant Belgian regression formulae (regression formulae are available for one, two, three and four third molars). To determine if the formulae produced age estimates comparable to those in the Belgian study, the percentage of Indian subjects whose actual age fell within the 68% confidence interval (CI) (calculated from the ± 1 S.D. value available for each Belgian formula) was ascertained. If ? 68% of Indian subjects' age fell inside this interval, it indicates that the Belgian formulae are applicable in Indians. To assess the suitability of the Belgian formulae in predicting juvenile/adult status in Indians, the accuracy of the age estimation per se was not considered, rather, the number of correct

Bhowmik, Biyas; Acharya, Ashith B; Naikmasur, Venkatesh G

2013-03-10

360

Infinite dilution diffusion coefficients of [Bmim]-based ionic liquids in water and its molar conductivities  

Microsoft Academic Search

In this work, we presented new experimental data of diffusion coefficients of four [Bmim (1-butyl-3-methylimidazolium)]-based ionic liquids in water at infinite dilution for temperatures ranging from 303.2 to 323.2K using Taylor dispersion technique. The investigated ILs were [Bmim][BF4 (tetrafluoroborate)], [Bmim][MeSO4 (methylsulfate)], [Bmim][PF6 (hexafluorophosphate)], and [Bmim][CF3SO3 (trifluoromethanesulfonate)]. The molar conductivities of these ionic liquids were also measured and the infinite dilution

Chun-Li Wong; Allan N. Soriano; Meng-Hui Li

2009-01-01

361

An accurate colon residue detection algorithm with partial volume segmentation  

E-print Network

is the second leading cause of cancer-related death in the United States. Earlier detection and removal) image-segmentation framework. A Markov random field (MRF) model was developed to reflect the prior Field I. Introduction Colon cancer is the second leading cause of cancer-related death in the United

362

Partially segmented deformable mirror  

DOEpatents

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.

Bliss, Erlan S. (Danville, CA); Smith, James R. (Livermore, CA); Salmon, J. Thaddeus (Livermore, CA); Monjes, Julio A. (San Ramon, CA)

1991-01-01

363

Partially segmented deformable mirror  

DOEpatents

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.

Bliss, E.S.; Smith, J.R.; Salmon, J.T.; Monjes, J.A.

1991-05-21

364

Effect of Erythrina mulungu on anxiety during extraction of third molars  

PubMed Central

Objectives: The aim of the present study was to evaluate the effect of Erythrina mulungu on the control of dental anxiety in patients who had under gone bilateral extraction of asymptomatic, impacted mandibular third molars. Material and Methods: In a randomized, double-blind, crossover study, 30 healthy volunteers (5 men and 25 women, over 18 years of age), received either 500mg of E.mulungu (Mulungu Matusa®) or 500 mg of placebo, p.o., one hour before surgical procedure. The level ofanxiety was assessed through questionnaire sand physical parameters, such as blood pressure, heart rate andoxygen saturation. Data were analyzed by Chi-square test, ANOVA (Tukey test) and Friedman with significance level of 5%. Results: A higher preference (Chi-square, p = 0.0062) for E. mulungu was observed for both genders. Volunteers with higher anxiety levels tended to to prefer E. mulungu. No statistically significant differences were verified in blood pressure (one-way ANOVA, p = 0.1259), heart rate (Friedman, p> 0.05) and oxygen saturation (Friedman, p = 0.7664) among periods and types of treatments. Conclusions: E. mulungu showed an anxiolytic effect without significant changes in physiological parameters. It could be considered as an alternative to control the anxiety in adult patients undergoing mandibular thirdmolars surgery. Key words:Anxiety, Erythrina mulungu, third molar, oral surgery. PMID:24880443

Silveira-Souto, Maria L.; São-Mateus, Carla R.; Groppo, Francisco C.

2014-01-01

365

In Search of a Better Option: Dexamethasone Versus Methylprednisolone in Third Molar Impaction Surgery  

PubMed Central

Background: Post-surgical complications like pain, swelling, impaired function cause transient morbidity for the patients leading to refrainment of the treatment. Various preemptive drugs are prescribed to prevent patients from such unpleasant situations. Both dexamethasone and methyl prednisolone can be used for this purpose in surgery of third molar impactions. Materials and Methods: This was a split-mouth study consisting 25 patients having Pell and Gregory’s Class II position B bilateral impactions. About 8 mg dexamethasone and 40 mg methyl prednisolone were prescribed randomly 1 hour prior to the surgery. Pain, swelling and trismus were noted on 1st, 2nd, 3rd and 7th day following surgery. Wilcoxon test was used to assess the significance between the parameters. Results: Reduction in swelling and trismus was found to be significantly more with dexamethasone than methyl prednisolone. However, no statistical significant difference was found in post-operative pain. Conclusion: Dexamethasone can be used as a potent preemptive drug for controlling post-operative complications in the removal of third molar impactions.

Darawade, Dattatraya A; Kumar, Santosh; Mehta, Rupal; Sharma, Anant Raghav; Reddy, G Sharaschandra

2014-01-01

366

Expression of Nfic during root formation in first mandibular molar of rat.  

PubMed

The transcription factor Nfic is a key regulator during tooth development. Nfic deficient mice exhibit short and abnormal molar roots and severely deformed incisors. Dental epithelial cells, known as Hertwig's epithelial root sheath (HERS), participate in root formation. However, whether Nfic is involved in HERS-mesenchyme interaction remains unclear. In this study, the detail temporal and spatial expression pattern of Nfic during rat molar development was examined using immunohistochemistry and in situ hybridization. Nfic was detected in ameloblasts, dental follicle cells (DFCs) and dental papilla cells (DPCs), especially the DPCs close to dentin, from postnatal day 5 to day 16. Nfic expression in DPCs, DFCs and HERS cells was also examined by western blot and RT-PCR. Nfic was detected in DPCs and DFCs, but not in HERS cells. Co-culture experiment further indicated that Nfic mRNA expression in DPCs was elevated by the presence of HERS cells. Our results revealed that Nfic could be a marker gene for root odontoblasts differentiation initiation and its expression might be regulated through epithelial-mesenchymal interaction. PMID:25074584

Chen, Xiang; Chen, Guoqing; Feng, Lian; Jiang, Zongting; Guo, Weihua; Yu, Mei; Tian, Weidong

2014-12-01

367

Reliability of Third Molar Development for Age Estimation by Radiographic Examination (Demirjian’s Method)  

PubMed Central

Introduction: Dental age estimation methods are of particular value because teeth are highly resistant to mechanical, chemical, or physical impacts and time. Teeth are the strongest parts in the human body and are therefore very resistant to external influences, such as extreme temperatures, explosions, and other extreme conditions, which make them available for extensive postmortem periods. Aim: To correlate chronological age with dental age using Demirijian’s method. Materials and Methods: The study was carried out on 100 digital orthopantamograms (OPG) of patients in the age group of 7 to 24 years. During the analysis, Magnify’ and Ruler’ tools were used. Mandibular right third molar was used for entire study. Data collected was analysed by using SPSS software. Results: Development of third molar in all stages was found slightly earlier in males than in females, when chronological age was compared with dental age using Demirjian method. 88% subject showed statistically significant linear correlation between chronological age and developmental age using Demirjian’s method. Conclusion: The linear correlation between chronological age and dental age using to Demirjian’s method was more in age group above 16 years and less in age group below 16 years. Demirijian’s method is a reliable guide for age estimation in age group of 7 to 24 years of age. PMID:24995239

Patil, Swapnil N; Kamble, Seema D; Mowade, Tushar; Motghare, Pavan

2014-01-01

368

Identification of possible factors impacting dental students' ability to locate MB2 canals in maxillary molars.  

PubMed

This study examined the effect of the access size and straight-line path of access on third-year dental students' ability to locate a second mesiobuccal (MB2) canal in maxillary first and second molars. One hundred and six third-year dental students at one Faculty of Dentistry performed simulated root canal treatment with the aid of 2x magnification loupes on extracted teeth. A postgraduate endodontic student subsequently made a reasonable search for an untreated MB2 canal with the aid of a dental operating microscope. The mesiobuccal roots were then sectioned horizontally for determination of the canal configuration. The dental students were able to treat an MB2 canal in 15.8 percent of the teeth, but this was not associated with satisfactory access criteria. The postgraduate endodontic student identified an MB2 canal in 54.7 percent of the remaining tooth samples excluding those where the MB2 canal was found by the dental students; this represented 94.3 percent of those teeth confirmed by horizontal sectioning of the root to have an MB2 canal. The postgraduate student troughed, on average, 2.6 mm before negotiating the MB2 canal. As satisfactory access criteria and straight-line path of access did not correlate with the dental students' ability to find a second mesiobuccal canal, this result has important implications for educational goals with respect to endodontic treatment of maxillary molar teeth. PMID:24789839

Park, Ellen; Chehroudi, Babak; Coil, Jeffrey M

2014-05-01

369

Lorentzian Manifolds and Causal Sets as Partially Ordered Measure Spaces  

E-print Network

We consider Lorentzian manifolds as examples of partially ordered measure spaces, sets endowed with compatible partial order relations and measures, in this case given by the causal structure and the volume element defined by each Lorentzian metric. This places the structure normally used to describe spacetime in geometrical theories of gravity in a more general context, which includes the locally finite partially ordered sets of the causal set approach to quantum gravity. We then introduce a function characterizing the closeness between any two partially ordered measure spaces and show that, when restricted to compact spaces satisfying a simple separability condition, it is a distance. In particular, this provides a quantitative, covariant way of describing how close two manifolds with Lorentzian metrics are, or how manifoldlike a causal set is.

Luca Bombelli; Johan Noldus; Julio Tafoya

2012-12-04

370

Treatment effects of intraoral appliances with conventional anchorage designs for non-compliance maxillary molar distalization: a literature review.  

PubMed

Since the end of the 1970s, various appliances with intramaxillary anchorage for distalization of the upper molars have been described as an alternative to headgear. The major advantages of these innovative appliances are that they act permanently and are independent of patient compliance. The purpose of this study was to compare the efficiency, both quantitatively and qualitatively, of various appliance types with intramaxillary anchorage for non-compliance molar distalization. Eighty-five papers were reviewed, and 22 were identified as being suitable for inclusion. The selection was based on compliance with the following criteria: treatment group with at least 10 non-syndromal patients, conventional intraoral anchorage design using a palatal button and anchorage teeth, consistent cephalometric measurements in clinical-epidemiological studies, exact data on the course of treatment, and statistical presentation of the measured outcomes and their standard deviations. The results show that non-compliance molar distalization is possible with numerous different appliances. While molar distalization with standard pendulum appliances exhibited the largest values for dental-linear distalization, it also resulted in concurrent, substantial therapeutically undesirable distal tipping. However, specific modifications to the pendulum appliance allow achievement of almost bodily molar distalization. Different outcomes are quoted in the studies for the efficiency of loaded spring systems for distal molar movement, but it seems that the first class appliance and the palatal distal jet are more efficient than the vestibular Jones Jig. The studies identify anchorage loss as being found in the area of the incisors rather than the area of the first premolars. There was a trend for more substantial reciprocal side-effects to occur when only two teeth were included in the anchorage unit. Vertical components acting on the molars, premolars, and incisors, such as intrusion and extrusion, tended to be of secondary importance and, therefore, may be disregarded. PMID:18820306

Kinzinger, Gero S M; Eren, Mert; Diedrich, Peter R

2008-12-01

371

Tuesday, March 24, 2009 POSTER SESSION I: PLANETARY DIFFERENTIATION  

E-print Network

Molar Volume of CO2 in Peridotite Partial Melt at High Pressure [#1406] Using the sink/float method with carbonated and non-carbonated peridotite partial melts, the partial molar volume of CO2 is calculated at high in the Lherz peridotite (the type locality of terrestrial mantle lherzolite), and are used to constrain

Rathbun, Julie A.

372

Accelerated partial breast irradiation.  

PubMed

Local therapies to treat newly diagnosed breast cancer include a lumpectomy with radiation therapy or a mastectomy. The 20-year data from studies about the safety and efficacy of lumpectomy with full-breast radiation therapy support the safety of this regimen and its role to decrease the risk of ipsilateral recurrence and increase long-term survivorship of women with breast cancer. Accelerated partial breast irradiation (APBI) provides radiation therapy to the tumor bed but spares the remaining breast tissue. APBI accelerates the time required to complete the therapy regimen, with a range of one intraoperative session to five consecutive days compared to five to seven weeks. Several techniques exist to administer APBI, including the insertion of a balloon into the lumpectomy space. Of interest is the widespread use of APBI in community and academic settings that has preceded outcomes of large, randomized clinical trials. Because of selection bias in a number of small, single-institution, nonrandomized studies, published data are of limited value to ensure APBI as a standard of care. PMID:25253109

Bauer, Elfrida; Lester, Joanne L

2014-10-01

373

Partial disassembly of peroxisomes  

PubMed Central

Rat liver peroxisomes were subjected to a variety of procedures intended to partially disassemble or damage them; the effects were analyzed by recentrifugation into sucrose gradients, enzyme analyses, electron microscopy, and SDS PAGE. Freezing and thawing or mild sonication released some matrix proteins and produced apparently intact peroxisomal "ghosts" with crystalloid cores and some fuzzy fibrillar content. Vigorous sonication broke open the peroxisomes but the membranes remained associated with cores and fibrillar and amorphous matrix material. The density of both ghosts and more severely damaged peroxisomes was approximately 1.23. Pyrophosphate (pH 9) treatment solubilized the fibrillar content, yielding ghosts that were empty except for cores. Some matrix proteins such as catalase and thiolase readily leak from peroxisomes. Other proteins were identified that remain in mechanically damaged peroxisomes but are neither core nor membrane proteins because they can be released by pyrophosphate treatment. These constitute a class of poorly soluble matrix proteins that appear to correspond to the fibrillar material observed morphologically. All of the peroxisomal beta-oxidation enzymes are located in the matrix, but they vary greatly in how easily they leak out. Palmitoyl coenzyme A synthetase is in the membrane, based on its co-distribution with the 22-kilodalton integral membrane polypeptide. PMID:2989301

1985-01-01

374

Low partial discharge vacuum feedthrough  

NASA Technical Reports Server (NTRS)

Relatively discharge free vacuum feedthrough uses silver-plated copper conductor jacketed by carbon filled silicon semiconductor to reduce concentrated electric fields and minimize occurrence of partial discharge.

Benham, J. W.; Peck, S. R.

1979-01-01

375

Trigonometric Integrals via Partial Fractions  

ERIC Educational Resources Information Center

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.

Chen, H.; Fulford, M.

2005-01-01

376

Accuracy of identifying juvenile/adult status from third molar development using prediction probabilities derived from logistic regression analysis.  

PubMed

The use of third molars in predicting juvenile/adult status (molar development was assessed using Köhler's grading on 268 orthopantomograms of Indian subjects. Logistic regression analysis was applied to determine allocation accuracy of juvenile/adult status and the level of probability that is "reliable" in predicting juvenile/adult status. Allocation accuracies ranged between 75.8% and 78.2% for the sexes combined, with minimal male-female differences. Adults were categorized more accurately than juveniles, suggesting that Köhler's grading puts Indian juveniles at greater risk of unwarranted punishment. In both sexes, juvenile/adult status was "reliably" predicted when the probability was >80% using individual third molars (excepting the lower right third molar in males); combining upper and lower third molars on the left/right sides, "reliable" predictions were possible when the probability was >80% and >90% for females and males, respectively. Overall, "reliable" juvenile/adult status prediction was achieved in c. 36% of subjects. PMID:24313875

Acharya, Ashith B; Bhowmik, Biyas; Naikmasur, Venkatesh G

2014-05-01

377

Differences in molar relationships and occlusal contact areas evaluated from the buccal and lingual aspects using 3-dimensional digital models  

PubMed Central

Objective The aims of this study were to use a 3-dimensional (3D) system to compare molar relationship assessments performed from the buccal and lingual aspects, and to measure differences in occlusal contact areas between Class II and Class I molar relationships. Methods Study casts (232 pairs from 232 subjects, yielding a total of 380 sides) were evaluated from both the buccal and lingual aspects, so that molar relationships could be classified according to the scheme devised by Liu and Melsen. Occlusal contact areas were quantified using 3D digital models, which were generated through surface scanning of the study casts. Results A cusp-to-central fossa relationship was observed from the lingual aspect in the majority of cases classified from the buccal aspect as Class I (89.6%) or mild Class II (86.7%). However, severe Class II cases had lingual cusp-to-mesial triangular fossa or marginal ridge relationships. Mean occlusal contact areas were similar in the Class I and mild Class II groups, while the severe Class II group had significantly lower values than either of the other 2 groups (p < 0.05). Conclusions Buccal and lingual assessments of molar relationships were not always consistent. Occlusal contact areas were lowest for the Class II-severe group, which seems to have the worst molar relationships - especially as seen from the lingual aspect. PMID:23112949

Jang, Sook-Yoon; Kim, Minji

2012-01-01

378

Economic modeling of sealing primary molars using a "value of information" approach.  

PubMed

The objective was to evaluate 2 primary molar sealant strategies for publicly insured children using an "expected value of perfect information" (EVPI) approach. We converted a 10,000-observation tooth-level cost-effectiveness simulation model comparing 2 primary molar sealant strategies - always seal (AS) and standard care (SC) - with a 1,250-observation child-level model. Costs per child per restoration or extraction averted were estimated. Opportunity losses under the AS strategy were determined for children for whom SC was the optimal choice. We determined the EVPI by multiplying mean opportunity losses by the projected incident population of publicly insured 3-year-olds in the US over 10 years with costs discounted at 2%. All analyses were conducted under assumptions of high and low intrachild correlations between at-risk teeth. The AS strategy cost $43.68 over SC (95% CI: -$5.50, $92.86) per child per restoration or extraction averted under the high intrachild correlation assumption and $15.54 (95% CI $7.86, $23.20) under the low intrachild correlation. Under high intrachild correlation, mean opportunity losses were $80.28 (95% CI: $76.39, $84.17) per child, and AS was the optimal strategy in 31% of children. Under low correlation, mean opportunity losses were $14.61 (95% CI: $12.20, $17.68) and AS was the optimal strategy in 87% of children. The EVPI was calculated at $530,813,740 and $96,578,389 (for high and low intrachild correlation, respectively), for a projected total incident population of 8,059,712 children. On average, always sealing primary molars is more effective than standard care, but widespread implementation of this preventive approach among publicly insured children would result in large opportunity losses. Additional research is needed to identify the subgroups of publicly insured children who would benefit the most from this effective and potentially cost-saving public health intervention. PMID:25056993

Ney, J P; van der Goes, D N; Chi, D L

2014-09-01

379

Volumes, heat capacities and solubilities of amyl compounds in decyltrimethylammonium bromide aqueous solutions  

Microsoft Academic Search

Apparent molar heat capacities and volumes of amylamine (PentNH2) 0.02m, capronitrile (PentCN) 0.02m and nitropentane (PentNO2) 0.009m in decyltrimethylammonium bromide (DeTAB) micellar solutions, in water and in octane were measured at 25°C. By assuming that their concentration approaches the standard infinite dilution state, heat capacities and volumes were rationalized by means of previously reported equations following which the distribution constant

R. Lisi; S. Milioto; R. Triolo

1989-01-01

380

Using Dalton's Law of Partial Pressures to Determine the Vapor Pressure of a Volatile Liquid  

ERIC Educational Resources Information Center

This experiment, designed for a general chemistry laboratory, illustrates the use of Dalton's law of partial pressures to determine the vapor pressure of a volatile liquid. A predetermined volume of air is injected into a calibrated tube filled with a liquid whose vapor pressure is to be measured. The volume of the liquid displaced is greater than…

Hilgeman, Fred R.; Bertrand, Gary; Wilson, Brent

2007-01-01

381

Solution properties of high-molar-mass hyaluronans: the biopolymer degradation by ascorbate.  

PubMed

An accurate molecular characterization, molar mass and size distributions, of 10 hyaluronan (HA) samples was performed by using a multi-angle light scattering detector connected on-line to a size exclusion chromatographic system. The dynamic viscosity eta of the HA solutions was investigated using a rotational viscometer. On monitoring the sample dynamic viscosity for up to 5h, a small however constant increase of the eta value was observed, indicating rheopectic behavior of all 10 HA solutions. Addition of ascorbic acid to the HA solutions caused significant changes in the rheological properties of the samples investigated. The change of eta values in the course of time was explained by the redox reactions (caused by the added ascorbate) that occur during the dynamic viscosity monitoring. PMID:17362893

Soltés, Ladislav; Valachová, Katarína; Mendichi, Raniero; Kogan, Grigorij; Arnhold, Juergen; Gemeiner, Peter

2007-06-11

382

Stepwise excavation in a permanent molar: 17-year follow-up.  

PubMed

The current study presents a 17-year clinical report of stepwise excavation and indirect pulp capping in a lower right first molar, with great dentin destruction and a lack of dentin support of the cusps. At the first appointment, indirect pulp capping with calcium hydroxide and a temporary filling with zinc oxide cement were performed to minimize the risk of pulp exposure during excavation. After 45 days, the remaining carious tissue was removed and a restoration with glass-ionomer lining (Vitrebond) and resin composite (P-50) was performed. Satisfactory morphology and function of the restoration and pulp vitality were preserved for 17 years, thus indicating that stepwise excavation can be a good treatment alternative in selected cases. PMID:20672734

Lima, Fernanda Ferruzzi; Pascotto, Renata Corrêa; Benetti, Ana Raquel

2010-01-01

383

Coumarin-bearing triarylamine sensitizers with high molar extinction coefficient for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Coumarin unit is introduced into triarylamine and three organic sensitizers are designed and synthesized with triarylamine bearing coumarin moiety as the electron donor, conjugated system containing thiophene unit as the ?-bridge, and cyanoacetic acid moiety as the electron acceptor. The light-harvesting capabilities and photovoltaic performance of these dyes are investigated systematically with the comparison of different ?-bridges. High molar extinction coefficients are observed in these triarylamine dyes and the photocurrent and photovoltage are increased with the introduction of another thiophene or benzene. Optimal photovoltaic performance (? = 6.24%, Voc = 690 mV, Jsc = 14.33 mA cm-2, and ff = 0.63) is observed in the DSSC based on dye with thiophene-phenyl unit as the ?-conjugated bridge under 100 mW cm-2 simulated AM 1.5 G solar irradiation.

Zhong, Changjian; Gao, Jianrong; Cui, Yanhong; Li, Ting; Han, Liang

2015-01-01

384

Multiple Dens Evaginatus of Premolars and Molars in Chinese Dentition: A Case Report and Literature Review  

PubMed Central

Dens evaginatus (DE) is a dental anomaly that occurs as an accessory tubercle on the occlusal or lingual surface of a tooth. The authors provide a literature review and report a rare case in which DE occurs on multiple mandibular premolars and maxillary molars. The patient is a 26-year-old Chinese woman, with a chief complaint of gingival bleeding. DE affecting teeth 17, 27, 35, and 45 was found during clinical examination. For treatment of the patient, we reduced the opposing occluding teeth, while undertaking progressive grinding of the tubercles for six months. We followed-up for a year. This suggests the importance of examining for multiple DE during clinical practice. PMID:21125795

Rao, Yan-gang; Guo, Li-yang; Hu, Tao

2010-01-01

385

Molar microwear of subfossil lemurs: improving the resolution of dietary inferences.  

PubMed

In this study we use molar microwear analyses to examine the trophic distinctions among various taxa of Malagasy subfossil lemurs. High resolution casts of the teeth of Megaladapis, Archaeolemur, Palaeopropithecus, Babakotia, and Hadropithecus were examined under a scanning electron microscope. Megaladapis was undoubtedly a browsing folivore, but there are significant differences between species of this genus. However, dietary specialists appear to be the exception; for example, Palaeopropithecus and Babakotia probably supplemented their leaf-eating with substantial amounts of seed-predation, much like modern indrids. Hadropithecus was decidedly not like the modern gelada baboon, but probably did feed on hard objects. Evidence from microwear and coprolites suggests that Archaeolemur probably had an eclectic diet that differed regionally and perhaps seasonally. Substantial trophic diversity within Madgascar's primate community was diminished by the late Quaternary extinctions of the large-bodied species (>9 kg). PMID:12457853

Rafferty, K L; Teaford, M F; Jungers, W L

2002-11-01

386

A comparison of the effects of methylprednisolone and tenoxicam on pain, edema, and trismus after impacted lower third molar extraction  

PubMed Central

Background The aim of the present study was to compare the effects of preemptive intravenous tenoxicam and methylprednisolone administrations on extraction of impacted third molars. Material/Methods This was a placebo-controlled, randomized, double-blind, clinical trial. A total of 60 adult patients ages 18–40 years with the complaints of impacted third molar teeth were included in the study. Results The postoperative swelling ratios (p<0.05) and pain scores (p<0.05) were significantly better in both study groups than in the control group and there was no statistically significant difference between methylprednisolone and tenoxicam groups with regards to the edema and pain relief. Conclusions Preoperative administration of 80 mg methylprednisolone achieves better control of trismus than tenoxicam without any significant differences in edema and pain control in impacted third molar teeth extraction. PMID:24473372

Ilhan, Ozgur; Agacayak, Kamil Serkan; Gulsun, Belgin; Koparal, Mahmut; Gunes, Nedim

2014-01-01

387

Molar-mass measurement of a 28Si-enriched silicon crystal for determination of the Avogadro constant  

NASA Astrophysics Data System (ADS)

The molar mass of a 28Si-enriched crystal was measured at the National Metrology Institute of Japan to determine the Avogadro constant by the x-ray crystal density method as part of the International Avogadro Coordination project. The molar mass was determined by isotope ratio measurements using a multicollector inductively coupled plasma mass spectrometer combined with an isotope dilution technique. The 28Si-enriched crystal was dissolved in tetramethylammonium hydroxide and three different blended solutions were used to correct for mass bias in the measurement. The molar mass of the 28Si-enriched crystal was determined to be 27.976?970 09 g mol-1 with a standard uncertainty of 0.000?000 14 g mol-1. This corresponds to a relative standard uncertainty of 5.2 × 10-9. This result is consistent with measurements reported by the Physikalisch-Technische Bundesanstalt, Germany.

Narukawa, Tomohiro; Hioki, Akiharu; Kuramoto, Naoki; Fujii, Kenichi

2014-06-01

388

Reliability of CBCT as an assessment tool for mandibular molars furcation defects  

NASA Astrophysics Data System (ADS)

Introduction. In numerous clinical situations it is not possible to have an exact clinical evaluation of the furcation defects. Recently the use of CBCT in periodontology has led to an increased precision in diagnostic. Aim. To determine the accuracy of CBCT as diagnostic tool of the furcation defects. Material and method. 19 patients with generalised advanced chronic periodontitis were included in this study, presenting a total of 25 lower molars with different degrees of furcation defects. Clinical and digital measurements (in mm) were performed on all the molars involved. The data obtained has been compared and statistically analysed. Results. The analysis of primary data has demonstrated that all the furcation grade II and III defects were revealed using the CBCT technique. Regarding the incipient defects (grade I Hamp < 3mm), the dimensions measured on CBCT images were slightly bigger. The results have shown that 84% of the defects detected by CBCT have been confirmed by clinical measurements. These data are similar to those revealed by other studies1. Conclusions. The use of CBCT technique in evaluation and diagnosis of human mandibular furcation defects can provide many important information regarding the size and aspect of the interradicular defect, efficiently and noninvasively. CBCT technique is used more effectively in detection of advanced furcation degree compared to incipient ones. However, the CBCT examination cannot replace, at least in this stage of development, the clinical measurements, especially the intraoperative ones, which are considered to represent the „golden standard" in this domain.

Marinescu, Adrian George; Boariu, Marius; Rusu, Darian; Stratul, Stefan-Ioan; Ogodescu, Alexandru

2014-01-01

389

Temperature dependent near UV molar absorptivities of several small aldehydes in aqueous solution  

NASA Astrophysics Data System (ADS)

Temperature-dependent molar absorptivities are reported for benzaldehyde, acrolein, isobutyraldehyde, pentanal, and hexanal in aqueous solution. With the exception of acrolein, molar absorptivities are given at eight temperatures in the range 6.5-69.5°C for wavelengths greater than 200 nm, a spectral resolution of 2.0 nm, and a spacing of 2.5 nm. For acrolein, data are given over a more limited range of temperatures and wavelengths. For benzaldehyde and acrolein, no hydration occurs, as expected, and only small changes in the shape and intensity of the spectrum with temperature are observed. For the other three aldehydes, the hydration reaction RCHO+ H2O? RCH(OH)2; K hyd=[ RCH(OH)2]/[ RCHO] is the major source for the observed change in intensity with temperature. Based on these changes, the following thermodynamic parameters are obtained for the hydration reaction at T = 25° C: isobutyraldehyde, Khyd = 0.51 ± 0.06, ?H = - 26.8 ± 1.9 kJ mol -1, ?S = - 95 ± 7 J mol -1 K -1; pentanal, Khyd = 0.55 ± 0.05, ?H = - 24.6 ± 1.6 kJ mol -1, ?S = - 87 ± 8 J mol -1 K -1; hexanal, Khyd = 0.49 ± 0.05, ?H = - 25.3 ± 2.2 kJ mol -1, ?S = - 91 ± 8 J mol -1 K -1. The present results are compared to data obtained previously for smaller aliphatic aldehydes, and the implications of the results for aqueous phase atmospheric chemistry are discussed.

Sham, Yuk Y.; Joens, Jeffrey A.

1995-02-01

390

Dental pulp of the third molar: a new source of pluripotent-like stem cells.  

PubMed

Dental pulp is particularly interesting in regenerative medicine because of the accessibility and differentiation potential of the tissue. Dental pulp has an early developmental origin with multi-lineage differentiation potential as a result of its development during childhood and adolescence. However, no study has previously identified the presence of stem cell populations with embryonic-like phenotypes in human dental pulp from the third molar. In the present work, we describe a new population of dental pulp pluripotent-like stem cells (DPPSCs) that were isolated by culture in medium containing LIF, EGF and PDGF. These cells are SSEA4(+), OCT3/4(+), NANOG(+), SOX2(+), LIN28(+), CD13(+), CD105(+), CD34(-), CD45(-), CD90(+), CD29(+), CD73(+), STRO1(+) and CD146(-), and they show genetic stability in vitro based on genomic analysis with a newly described CGH technique. Interestingly, DPPSCs were able to form both embryoid-body-like structures (EBs) in vitro and teratoma-like structures that contained tissues derived from all three embryonic germ layers when injected in nude mice. We examined the capacity of DPPSCs to differentiate in vitro into tissues that have similar characteristics to mesoderm, endoderm and ectoderm layers in both 2D and 3D cultures. We performed a comparative RT-PCR analysis of GATA4, GATA6, MIXL1, NANOG, OCT3/4, SOX1 and SOX2 to determine the degree of similarity between DPPSCs, EBs and human induced pluripotent stem cells (hIPSCs). Our analysis revealed that DPPSCs, hIPSC and EBs have the same gene expression profile. Because DPPSCs can be derived from healthy human molars from patients of different sexes and ages, they represent an easily accessible source of stem cells, which opens a range of new possibilities for regenerative medicine. PMID:22467856

Atari, Maher; Gil-Recio, Carlos; Fabregat, Marc; García-Fernández, Dani; Barajas, Miguel; Carrasco, Miguel A; Jung, Han-Sung; Alfaro, F Hernández; Casals, Nuria; Prosper, Felipe; Ferrés-Padró, Eduard; Giner, Luis

2012-07-15

391

Lipid Concentration and Molar Ratio Boundaries for the Use of Isotropic Bicelles  

PubMed Central

Bicelles are model membranes generally made of long-chain dimyristoylphosphatidylcholine (DMPC) and short-chain dihexanoyl-PC (DHPC). They are extensively used in the study of membrane interactions and structure determination of membrane-associated peptides, since their composition and morphology mimic the widespread PC-rich natural eukaryotic membranes. At low DMPC/DHPC (q) molar ratios, fast-tumbling bicelles are formed in which the DMPC bilayer is stabilized by DHPC molecules in the high-curvature rim region. Experimental constraints imposed by techniques such as circular dichroism, dynamic light scattering, or microscopy may require the use of bicelles at high dilutions. Studies have shown that such conditions induce the formation of small aggregates and alter the lipid-to-detergent ratio of the bicelle assemblies. The objectives of this work were to determine the exact composition of those DMPC/DHPC isotropic bicelles and study the lipid miscibility. This was done using 31P nuclear magnetic resonance (NMR) and exploring a wide range of lipid concentrations (2–400 mM) and q ratios (0.15–2). Our data demonstrate how dilution modifies the actual DMPC/DHPC molar ratio in the bicelles. Care must be taken for samples with a total lipid concentration ?250 mM and especially at q ? 1.5–2, since moderate dilutions could lead to the formation of large and slow-tumbling lipid structures that could hinder the use of solution NMR methods, circular dichroism or dynamic light scattering studies. Our results, supported by infrared spectroscopy and molecular dynamics simulations, also show that phospholipids in bicelles are largely segregated only when q > 1. Boundaries are presented within which control of the bicelles’ q ratio is possible. This work, thus, intends to guide the choice of q ratio and total phospholipid concentration when using isotropic bicelles. PMID:24797658

2014-01-01

392

Distribution of BMP6 in the alveolar bone during mouse mandibular molar eruption.  

PubMed

Eruption requires synchrony of the tooth with the surrounding tissues, particularly the bone. One important step during eruption is remodelling of the alveolar bone at the base of the tooth and along the roots. Expression of BMP6 was reported to be increased in the basal half of the dental follicle prior to eruption and inhibition of BMP6 affected bone formation at the base of the alveolar crypt. The aim of this study was to further investigate BMP6 protein in relation to tooth eruption and the corresponding bone remodelling using temporospatial correlations of BMP6 localization with morphogenetic events (proliferation, differentiation, apoptosis and bone apposition/resorption), other BMPs (BMP2 and BMP7) and three-dimensional images of tooth-bone development. BMP6 expression pattern was mapped in the mandibular molar teeth and related structures around eruption. Localization of BMP6 dominated in osteoblasts, in regions of bone formation within the alveolar crypt. These findings positively correlated with proliferation at the tooth base region, osteocalcin expression in the osteoblasts/osteocytes and BMP2 and BMP7 presence in the alveolar bone surrounding the tooth. Osteoclast activity and apoptotic elimination in the root region gradually decreased before eruption and totally ceased at eruption stages. Generally, BMP6 positively correlated with BMP2, BMP7 and osteocalcin-positive osteoblasts, and areas of bone remodelling. Moreover, BMP6 was found in the periodontium and cementoblasts. BMP6 expression in the alveolar bone accompanied tooth eruption. Notably, the expression pattern of BMP6 in the bone did not differ around individual molar teeth at the same stage of development. The expression of BMP6 in periodontal ligaments may contribute to interaction between the tooth and bone during the eruption and anchoring process. PMID:25084210

Oralová, Veronika; Chlastáková, Ivana; Radlanski, Ralf Johannes; Matalová, Eva

2014-01-01

393

Manual and Rotary Instrumentation Ability to Reduce Enterococcus faecalis Associated with Photodynamic Therapy in Deciduous Molars.  

PubMed

This aim of this study was to assess the ability of manual or rotary instrumentation associated with photodynamic therapy (PDT) to reduce Enterococcus faecalis using three combinations of light/photosensitizers: toluidine blue O/laser, fuchsin/halogen light and fuchsin/LED. Twenty deciduous molars were selected and contaminated with Enterococcus faecalis (McFarland 0.5 scale). Working length determination was performed by visual method. The teeth were randomly divided into two groups: G1 (n=10): manual instrumentation (Kerr-type files) and G2 (n=10): rotary instrumentation (ProTaper system). The bacteria were collected three times using sterile paper cones compatible with the anatomic diameter of the root canal for 30 s before and after instrumentation and after PDT. The samples were diluted in peptone water, seeded on blood agar plates and incubated in an oven at 37 °C for colony-forming units counting. The decrease of E. faecalis counts after instrumentation and after PDT was compared using the Wilcoxon test, t-test and Kruskal Wallis test. A significant reduction of E. faecalis occurred after manual and rotary instrumentation and after PDT using the three combinations of light/photosensitizer (p<0.05). It may be concluded that both rotary and manual instrumentation reduced E. faecalis. Fuchsin with halogen light or LED irradiation and toluidine blue O with laser irradiation can be used to reduce E. faecalis in root canals of primary molars. PDT can be used as an adjuvant to conventional endodontic treatment. PMID:25590196

Pinheiro, Sérgio Luiz; Silva, Josianne Neres da; Gonçalves, Rafael Orro; Villalpando, Karina Teixeira

2014-12-01

394

Treatment Outcomes of Primary Molars Direct Pulp Capping after 20 Months: A Randomized Controlled Trial  

PubMed Central

Introduction The aim of this randomized controlled trial was to compare the radiographic and clinical success rates of direct pulp capping (DPC) using ProRoot mineral trioxide aggregate (MTA) or calcium enriched mixture (CEM). Methods and Materials A total of 42 symptom-free carious vital primary molars (21 pairs) were selected in this split mouth trial and randomly pulpotomized in two experimental groups. Pinpoint pulp exposures were covered by the same blinded operator with MTA or CEM, and then restored by amalgam. Radiographic and clinical successes were evaluated at 20 month follow-up. Data were statistically analyzed using McNemar test. Results Nineteen patients were available for 20-month follow-up; only one failed tooth was extracted in the CEM group. All available teeth were symptom-free, however, the final evaluated success rate was 89% in CEM (CI 95%: 0.82-0.96) and 95% in MTA (CI 95%: 0.85-1) groups without statistical difference (P=0.360). Worst case scenario was applied for missing value analysis; assuming that the 2 lost cases in CEM group had failed and the only lost case in MTA group was due to treatment success, as a result the success of CEM and MTA were 81% (CI 95%: 0.72-0.90) and 95% (CI 95%:0.85-1), respectively, with no statistical difference (P=0.078). In the reverse scenario, the success of MTA and CEM were 86% (CI 95%: 0.78-0.94) and 90% (CI 95%: 0.82-0.98), respectively; again with no statistical difference (P=0.479). Conclusion Effectiveness of MTA and CEM biomaterials for primary molars’ DPC was similar; CEM can be a suitable alternative for MTA. PMID:24171019

Fallahinejad Ghajari, Masoud; Asgharian Jeddi, Tahereh; Iri, Sonay; Asgary, Saeed

2013-01-01

395

The Annotated Mina, Volume Two  

E-print Network

1 Mina de Malfois Volume Two Disclaimer: This is a work of fiction. No resemblance is intended to any person or persons living, dead, or online. No BNFs were harmed in the making of this fic. Permissions: These stories... and characters are the sole property of the author, but she lends them out for fanfic and fanart. A partial list of Mina de Malfois/Sanguinity things by other people can be found at the back of this volume. For further Minaverseness, try tracking down...

2014-03-10

396

C++ Templates as Partial Evaluation  

Microsoft Academic Search

This paper explores the relationship between C++ templates and partial evaluation. Templates were designed to support generic programming, but unintentionally provided the ability to perform compile-time computations and code generation. These features are completely accidental, and as a result their syntax is awkward. By recasting these features in terms of partial evaluation, a much simpler syntax can be achieved. C++

Todd L. Veldhuizen

1999-01-01

397

Volume Determination of Globular Proteins by Molecular Dynamics  

E-print Network

Molecular dynamics simulations of myoglobin and aspartate aminotransferase, with explicit solvent, are shown to accurately reproduce the experimentally measured molar volumes. Single amino-acid substitution at VAL39 of aspartate aminotransferase is known to produce large volumetric changes in the enzyme, and this effect is demonstrated in simulation as well. This molecular dynamics approach, while more computationally expensive that extant computational methods of determining the apparent volume of biological systems, is quite feasible with modern computer hardware and is shown to yield accurate volumetric data with as little as several nanoseconds of dynamics.

Belof, Jonathan L; Larsen, Randy W; Space, Brian

2014-01-01

398

Volume Determination of Globular Proteins by Molecular Dynamics  

E-print Network

Molecular dynamics simulations of myoglobin and aspartate aminotransferase, with explicit solvent, are shown to accurately reproduce the experimentally measured molar volumes. Single amino-acid substitution at VAL39 of aspartate aminotransferase is known to produce large volumetric changes in the enzyme, and this effect is demonstrated in simulation as well. This molecular dynamics approach, while more computationally expensive that extant computational methods of determining the apparent volume of biological systems, is quite feasible with modern computer hardware and is shown to yield accurate volumetric data with as little as several nanoseconds of dynamics.

Jonathan L. Belof; Edward W. Lowe; Randy W. Larsen; Brian Space

2014-04-06

399

Three Independent Mesial Canals in a Mandibular Molar: Four-Year Followup of a Case Using Cone Beam Computed Tomography  

PubMed Central

Endodontic treatment of mandibular molars is challenging because of variable root canal morphology. The nonsurgical endodontic management of a mandibular first molar presenting an independent middle mesial canal is reported. After coronal access, additional clinical inspection of the mesial canals' orifices and their interconnecting groove using an endodontic explorer and 4.5× loupes enabled the identification of the middle mesial canal orifice. All root canals were chemomechanically prepared and filled. The tooth was asymptomatic and functional after 4?years of followup. Cone beam computed tomography (CBCT) images revealed normal periapical status and three-dimensional (3D) anatomical aspects of the root canal system. PMID:23662215

de Paula, Adrianne Freire; Brito-Júnior, Manoel; Quintino, Alex Carvalho; Camilo, Carla Cristina; Cruz-Filho, Antônio Miranda; Sousa-Neto, Manoel Damião

2013-01-01

400

Penetration of experimental infiltrants with different penetration coefficients and ethanol addition into natural caries lesions in primary molars.  

PubMed

This study evaluated the influence of the penetration coefficient (PC) and ethanol addition on the penetration depth (PD) of experimental infiltrants into proximal caries lesions in primary molars. Caries lesions (n = 45) were randomly treated with 1 of 4 experimental infiltrants (PC63; PC185; PC204; PC391) for 5 min. Lesion depths and PDs were analysed using dual fluorescence confocal microscopy. Lesions were almost completely infiltrated in all groups. Median PDs and percentage penetrations were not significantly different between groups (p > 0.05). When applied for 5 min, all tested infiltrants were able to infiltrate proximal caries in primary molars nearly completely. PMID:22472477

Paris, S; Soviero, V M; Chatzidakis, A J; Meyer-Lueckel, H

2012-01-01

401

A comparitive study of diclofenac transdermal patch against oral diclofenac for pain control following removal of mandibular impacted third molars  

Microsoft Academic Search

Objective  The objectives of this study was to evaluate subjectively the analgesic efficacy of Oral Diclofenac Sodium against Diclofenac\\u000a Sodium Transdermal patch in the management of postoperative pain following surgical removal of impacted mandibular third molars.\\u000a \\u000a \\u000a \\u000a Materials and methods  Twenty healthy subjects belonging to both the sexes in the age group of 18–40 years with bilateral mesioangular impactions\\u000a of mandibular third molar

Prithvi S. Bachalli; H. Nandakumar; N. Srinath

2009-01-01

402

CBCT diagnosis and endodontic management of a maxillary first molar with unusual anatomy of two palatal canals: A case report  

PubMed Central

It is crucial for any clinician to have a thorough knowledge about the normal anatomy of tooth and always be vigilant for any variations to ensure endodontic success. An anatomic variant like additional canals in the palatal root of maxillary molar is not commonly reported. This clinical case report presents the application of cone beam computed tomography as a useful imaging technique in endodontics for the management of teeth with aberrant anatomy. Here, maxillary first molar having two canals in the palatal root, two canals in mesiobuccal root and one canal in distobuccal root was managed successfully using cone beam computed tomography scan as a diagnostic aid. PMID:25125860

Sharma, Sarang; Sharma, Vivek; Grover, Shibani; Mittal, Meenu

2014-01-01

403

Comparing Volumes  

NSDL National Science Digital Library

The purpose of this lab is to investigate volume (capacity). Using multiplicative comparisons, students will try to predict how many times the amount of water of one container will fit in another container.

2011-01-01

404

Partial confinement photonic crystal waveguides  

SciTech Connect

One-dimensional photonic crystal waveguides with an incomplete photonic band gap are modeled and proposed for an integration application that exploits their property of partial angular confinement. Planar apodized photonic crystal structures are deposited by plasma enhanced chemical vapor deposition and characterized by reflectivity as a function of angle and polarization, validating a partial confinement design for light at 850 nm wavelength. Partial confinement identifies an approach for tailoring waveguide properties by the exploitation of conformal film deposition over a substrate with angularly dependent topology. An application for an optoelectronic transceiver is demonstrated.

Saini, S.; Hong, C.-Y.; Pfaff, N.; Kimerling, L. C.; Michel, J. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2008-12-29

405

Análise comparativa entre os anestésicos locais Articaína 4% e Prilocaína 3% na extração de terceiros molares retidos em humanos  

Microsoft Academic Search

Comparative analysis between the local anesthesics Articaine 4% and Prilocaine 3% on human third molar removals. The local anesthesics are the most used drugs in Dentistry. They are frequently used in surgery, because pain has been described as an unpleasant experience, both on sensorial and psychological levels. The aim of this study was to obtain further knowledge about articaine 4%

Fausto Rodrigo Victorino; Aparecido Neri Daniel; Liogi Iwaki Filho; Edevaldo Tadeu Camarini; Josmar Mazucheli; Ângelo José Pavan

2004-01-01

406

on the basis of regressions of molar area versus body mass in living primates29 . The smaller  

E-print Network

on the basis of regressions of molar area versus body mass in living primates29 . The smaller primate from this locality is Eosimias centennicus, a basal anthropoid that weighed 90­ 180 g on the basis derived from multiple regressions). Regressions of talar dimensions versus body mass in living primates30

Packer, Alissa A.

407

Use of palatal miniscrew anchorage and lingual multi-bracket appliances to enhance efficiency of molar scissors-bite correction.  

PubMed

This article reports the successful treatment method of scissors-bite correction using miniscrew anchorage and a lingual multi-bracket appliance. A female patient, 17 years and 4 months old, had a chief complaint of crowding of anterior teeth. The patient was given the diagnosis of Angle Class I malocclusion with bimaxillary protrusion and incisor crowding. She also showed a scissors-bite of the second molar on the right side. Miniscrews were inserted into the palatal region of the upper second molar to reinforce the anchorage, and a lingual multi-bracket appliance was placed into the maxilla. Miniscrews inserted palatally were used to correct the scissors-bite in the first 3 months; afterward, they were used to retract the six anterior teeth. The total active treatment period was 26 months. Because of the bite-plane effect, the upper and lower molars were separated in occlusion, and the scissors-bite was corrected effectively within a short time. The combined use of palatal miniscrew anchorage and lingual multi-bracket appliances enhances efficiency of molar scissors-bite correction. PMID:19413381

Tamamura, Nagato; Kuroda, Shingo; Sugawara, Yasuyo; Takano-Yamamoto, Teruko; Yamashiro, Takashi

2009-05-01

408

The Role of Mandibular Third Molars on Lower Anterior Teeth Crowding and Relapse after Orthodontic Treatment: A Systematic Review  

PubMed Central

Aims. To evaluate the role of third molars in the development of crowding or relapse after orthodontic treatment in the anterior segment of the dental arch. Methods. PubMed search of the literature was performed selecting all the articles relevant to the topic and limiting the studies to controlled trials on humans and written in English language. Systematic review was conducted according to the PRISMA (preferred reporting items for systematic reviews and meta-analyses) statement. Results. A total of 12 clinical studies were included in the review. A high risk of bias was found in most of the articles, either because the relative items assessed were inadequate or because they were unclearly described. The third molars were not correlated with more severe anterior tooth crowding in most of the studies. However, four of them described a different outcome. Conclusion. Definitive conclusions on the role of the third molars in the development of anterior tooth crowding cannot be drawn. A high risk of bias was found in most of the trials, and the outcomes were not consistent. However, most of the studies do not support a cause-and-effect relationship; therefore, third molar extraction to prevent anterior tooth crowding or postorthodontic relapse is not justified. PMID:24883415

Zawawi, Khalid H.

2014-01-01

409

Partial belief and expert testimony  

E-print Network

My dissertation investigates two questions from within a partial belief framework: First, when and how should deference to experts or other information sources be qualified? Second, how closely is epistemology related to ...

Briggs, Rachael (Rachael Amy)

2009-01-01

410

Characterization of the molar masses of hemicelluloses from wood and pulps employing size exclusion chromatography and matrix-assisted laser desorption ionization time-of-flight mass spectrometry.  

PubMed

The molar mass parameters for arabino-4-O-methylglucuronoxylans, arabinohexenuronoxylans, 4-O-methylglucuronoxylans, hexenuronoxylans, and galactoglucomannans extracted from wood and pulps have been determined. To characterize different types of hemicelluloses, delignified wood (spruce, pine, larch, aspen, and birch) and chemical pulps (unbleached and totally chlorine-free bleached) were extracted with dimethyl sulfoxide (DMSO) or alkaline aqueous solutions. Size exclusion chromatography (SEC) with off-line matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-MS) were employed to characterize the molar masses. The hemicellulose extracts were separated by SEC into fractions each containing components with a narrow range of molar masses and the average molar mass of each fraction subsequently determined by MALDI-MS. The molar mass parameters for the hemicelluloses were then calculated on the basis of the SEC distribution curves and MALDI-MS spectra. As expected, in most cases the hemicelluloses extracted from wood (holocellulose) exhibited higher molar masses than did the corresponding hemicelluloses from chemical pulps. The molar mass parameters for hemicelluloses isolated from pulps derived from cooking samples of the same batch of softwood chips decreased in the following order: ASAM pulp > MSSAQ pulp > kraft pulp. The lowest molar masses were demonstrated by the glucuronoxylans extracted from pulps obtained by cooking with acidic sulfite. The xylans from bleached kraft pulp were characterized by molar masses that were only slightly lower than those of the corresponding xylans from unbleached pulp. The xylans extracted into DMSO exhibited somewhat lower molar masses than did the corresponding xylans extracted into alkaline aqueous solutions. In all cases the range of molar masses demonstrated by the hemicelluloses investigated was found to be rather narrow, i.e., the polydispersity index Mw/Mn was found to be approximately 1.1-1.4. PMID:11710047

Jacobs, A; Dahlman, O

2001-01-01

411

Clinical Application of Partial Splenic Embolization  

PubMed Central

Partial splenic embolization (PSE) is one of the intra-arterial therapeutic approaches of diseases. With the development of interventional radiology, the applications of PSE in clinical practice are greatly extended, while various materials are developed for embolization use. Common indications of PSE include hypersplenism with portal hypertension, hereditary spherocytosis, thalassemia, autoimmune hemolytic anemia, splenic trauma, idiopathic thrombocytopenic purpura, splenic hemangioma, and liver cancer. It is also performed to exclude splenic artery aneurysms from the parent vessel lumen and prevent aneurysm rupture, to treat splenic artery steal syndrome and improve liver perfusion in liver transplant recipients, and to administer targeted treatment to areas of neoplastic disease in the splenic parenchyma. Indicators of the therapeutic effect evaluation of PSE comprise blood routine test, changes in hemodynamics and in splenic volume. Major complications of PSE include the pulmonary complications, severe infection, damages of renal and liver function, and portal vein thrombosis. The limitations of PSE exist mainly in the difficulties in selecting the arteries to embolize and in evaluating the embolized volume.

Guan, Yong-Song; Hu, Ying

2014-01-01

412

Pulp-capping with recombinant human insulin-like growth factor I (rhIGF-I) in rat molars.  

PubMed

The aim of this study was to explore pulp healing and reparative dentinogenesis following pulp-capping by using recombinant human insulin-like growth factor I (rhIGF-I). Exposures were made through the mesial pulp horn in first upper molars in two-month-old Wistar rats. The pulp was covered with one dose of sterile 4% methylcellulose gel containing either 400 ng rhIGF-I or saline in contralateral controls. The exposure site was closed with sterile Teflon membrane, and the cavity was filled with IRM cement. Additional molars were capped with Dycal as controls. After 3, 7, or 28 days, animals were anesthetized and fixed by intravascular glutaraldehyde perfusion. Molars were decalcified and processed for histological analysis and cut with membrane and residual methacrylate from IRM in situ. Only specimens with acceptable pulp sealing according to blinded microscopy control were included. On day 3, identical inflammatory responses in the upper pulp were observed in molars with rhIGF-I gel or control gel. On day 7, granulation tissue ingrowth had partly replaced inflammatory infiltration in both groups. After 28 days, complete dentin bridging and tubular dentin formation were observed more frequently and closer to the test substance containing rhIGF-I. The reparative dentin response to capping with rhIGF-I was similar to that after the use of Dycal. In conclusion, microscopic control of membrane sealing in situ gives valid information on the more subtle pulp effects of growth factors. The observations suggest that pulp-capping of rat molars by means of rhIGF-I enhances reparative dentinogenesis in comparison with vehicle controls. PMID:12640754

Lovschall, H; Fejerskov, O; Flyvbjerg, A

2001-08-01

413

Brief communication: A morphometric analysis of the neandertal upper second molar Leuca I.  

PubMed

The scarcity of Neandertal remains from Southern Europe hampers our understanding of Neandertal variability, and can bias interpretations about Neandertal geographic variation. To address this issue, it is often important to reassess human remains that, while discovered decades ago, remain relatively unknown to the scientific community. In this contribution, we provide a complete state-of-the-art comparative morphometric analysis of Leuca I, an unworn left second upper molar (LM(2) ) discovered in 1958 in Bambino's Cave (near Santa Maria di Leuca, Apulia, Italy) and attributed to Homo neanderthalensis. Our study includes comparisons of standard metric and nonmetric data, a 2D image analysis of the occlusal surface and measurements of both 2D and 3D enamel thickness and dental tissue proportions. Although Leuca I follows the Neandertal M(2) s trend in some morphometric aspects (i.e., small relative occlusal polygon area), in other cases it falls to the higher end (for 3D average enamel thickness) or even outside (for 3D-relative enamel thickness) the Neandertal M(2) variability, thus increasing the known Neandertal range of variation. PMID:23999832

Benazzi, Stefano; Bailey, Shara E; Mallegni, Francesco

2013-10-01

414

Endodontic retreatment of a mandibular first molar with five root canal systems: an important clinical lesson.  

PubMed

The objective of root canal treatment is to perform complete debridement of the root canals and subsequent obturation to facilitate healing of periapical pathosis. However, this process becomes complicated with the presence of additional root canal systems. The purpose of the present article is to report successful non-surgical retreatment of a mandibular first molar with five canals. This case report discusses the clinical management of a previously root filled mandibular firstmolar with two missed canal systems; distolingual and an additional mesial canal known as the middle mesial canal. The post-treatment radiographs show successful obturation to length in all canals. The middle mesial canal was found to be associated with mesiolingual canal and categorised as confluent. The configuration of canals in the mesial root was type XV, based on the classification given by Sert and Bayirli. This case report highlights the importance of knowledge and its application in the management of abnormal anatomic variants which play a crucial role in the success of endodontic retreatment. PMID:24654237

Hasan, Muhammad; Umer, Fahad

2014-01-01

415

A 1-year clinical evaluation of fissure sealants on permanent first molars  

PubMed Central

Objective: To evaluate and compare the retention, marginal discoloration, surface texture and anatomical form of pit and fissure sealants. Materials and Methods: Thirty children between the ages of 6 and 10 years, who were attending the school health program regularly, had participated in the study. A split-mouth design was used in which the two fissure sealants (Helioseal-F and Glass ionomer Fuji VII) were randomly placed in 60 matched contralateral pairs of permanent molar teeth. Sealants were rated by a single trained and calibrated examiner using mouth mirrors and probes following the US Public Health Service criteria. The sealants were evaluated at 3 months, 6 months and 1 year intervals. Results: The data obtained for retention, marginal discoloration, surface texture and anatomical form of pit and fissure sealants were tabulated and compared statistically using the Chi-square test of significance. Conclusion: The Helioseal-F sealant was better than the Glass ionomer Fuji VII sealant with respect to retention, anatomical form and surface texture. Both the materials showed similar results with respect to marginal discoloration. PMID:22557898

Ninawe, Nupur; Ullal, Nayak Anand; Khandelwal, Vishal

2012-01-01

416

Comparison of two different flap designs in the surgical removal of bilateral impacted mandibular third molars.  

PubMed

The purpose of this study was to compare the effects of flap design on the postoperative sequelae of pain, swelling, trismus and wound dehiscence after surgical removal of bilateral impacted mandibular third molars (M3). 20 patients aged 20-30 years who required removal of bilateral impacted M3 were included in the study. Maximum interincisal opening and facial measurements were recorded preoperatively. Bayonet flap was used on one side and envelope flap on the other side for the removal of impacted M3. The effect of flap design on pain, swelling, trismus and wound dehiscence was evaluated postoperatively. Pain and wound dehiscence were significantly greater in the envelope flap group compared with the bayonet flap group (P<0.05). No significant difference in postoperative swelling and trismus was found in either group (P>0.05). The bayonet flap was superior to the envelope flap for postoperative pain and wound dehiscence. There was no difference in postoperative swelling and trismus between the two groups. PMID:20727713

Sandhu, A; Sandhu, S; Kaur, T

2010-11-01

417

[Evaluation of the bite block wedged between the maxillary and mandibular molars].  

PubMed

The purpose of this study was to compare our original bite block (T-X Block) wedged between the maxillary and mandibular molars, with the standard gum bite block, in 200 patients whose tracheas were intubated. During emergence from isoflurane anesthesia, no trouble occurred in T-X Block group (n = 100). On the other hand, lip damage and ejection of the bite block were found in 11 and 10 cases, respectively, in gum bite block group (n = 100). As another study, an opening between the maxillary and mandibular incisor edges was measured with T-X Block placed in twenty patients under general anesthesia. The inter-incisal distances in one way of using it as a smaller wedge and in the other way as a bigger one were 21.6 +/- 2.4 and 25.2 +/- 2.6 mm, respectively. Those values were significantly larger than thickness of the gum bite block. T-X Block is very useful because its use causes no complications and makes it easier to insert a naso-gastric tube as well as to clean the oral cavity with suction by giving a larger opening of the mouth. PMID:8997058

Katoh, H; Nishiyama, J; Takiguchi, M; Yamamoto, M; Fujita, K; Yamasaki, Y

1996-12-01

418

Properties of Calcium Phosphate Cements With Different Tetracalcium Phosphate and Dicalcium Phosphate Anhydrous Molar Ratios  

PubMed Central

Calcium phosphate cements (CPCs) were prepared using mixtures of tetracalcium phosphate (TTCP) and dicalcium phosphate anhydrous (DCPA), with TTCP/DCPA molar ratios of 1/1, 1/2, or 1/3, with the powder and water as the liquid. Diametral tensile strength (DTS), porosity, and phase composition (powder x-ray diffraction) were determined after the set specimens have been immersed in a physiological-like solution (PLS) for 1 d, 5 d, and 10 d. Cement dissolution rates in an acidified PLS were measured using a dual constant composition method. Setting times ((30 ± 1) min) were the same for all cements. DTS decreased with decreasing TTCP/DCPA ratio and, in some cases, also decreased with PLS immersion time. Porosity and hydroxyapatite (HA) formation increased with PLS immersion time. Cements with TTCP/DCPA ratios of 1/2 and 1/3, which formed calcium-deficient HA, dissolved more rapidly than the cement with a ratio of 1/1. In conclusion, cements may be prepared with a range of TTCP/DCPA ratios, and those with lower ratio had lower strengths but dissolved more rapidly in acidified PLS. PMID:19779581

Hirayama, Satoshi; Takagi, Shozo; Markovic, Milenko; Chow, Laurence C.

2009-01-01

419

Endodontic treatment of mandibular molar with root dilaceration using Reciproc single-file system  

PubMed Central

Biomechanical preparation of root canals with accentuated curvature is challenging. New rotatory systems, such as Reciproc, require a shorter period of time to prepare curved canals, and became a viable alternative for endodontic treatment of teeth with root dilaceration. Thus, this study aimed to report a clinical case of endodontic therapy of root with accentuated dilaceration using Reciproc single-file system. Mandibular right second molar was diagnosed as asymptomatic irreversible pulpitis. Pulp chamber access was performed, and glide path was created with #10 K-file (Dentsply Maillefer) and PathFile #13, #16 and #19 (Dentsply Maillefer) up to the temporary working length. The working length measured corresponded to 20 mm in the mesio-buccal and mesio-lingual canals, and 22 mm in the distal canal. The R25 file (VDW GmbH) was used in all the canals for instrumentation and final preparation, followed by filling with Reciproc gutta-percha cones (VDW GmbH) and AH Plus sealer (Dentsply Maillefer), using thermal compaction technique. The case has been receiving follow-up for 6 mon and no painful symptomatology or periapical lesions have been found. Despite the difficulties, the treatment could be performed in a shorter period of time than the conventional methods. PMID:24010084

Meireles, Daniely Amorin; Bastos, Mariana Mena Barreto; Marques, André Augusto Franco; Sponchiado, Emílio Carlos

2013-01-01

420

Study on Interactions of Continuous Low Power CO2 Laser with Malaysian Molar Teeth  

NASA Astrophysics Data System (ADS)

Recent studies have shown that CO2 lasers can successfully be used at low-energy densities in dentistry. The CO2 laser is effective for a dental hard tissue since it strongly absorbs light in certain regions of the infrared spectrum because of the carbonate and hydroxyl groups in the structure. In this study, nineteen samples of molars extracted human teeth were irradiated with low power CO2 laser. Laser power of 3W, 6W, 9W, 12W, 15W and 18W, with exposure time of 5 s and 10 s, and distance between laser aperture and sample of 4 cm were used. Laser power above 18W is seen to damage the teeth. The teeth compositions were analyzed using the Fourier Transform Infrared Spectroscopy (FTIR). High laser power caused higher reflectance of the beam because the increased in temperature increasing the rate of chemical reaction, hence, the products after the irradiation. This situation can be explained by the Arrhenius equation [1].

Ahmad, A. L.; Jaafar, M. S.; Ramzun, M. R.; Bermakai, M. Yahaya; Ismail, N. E.; Houssien, Hend A. A.

2010-07-01

421

Molar microwear textures and the diets of Australopithecus anamensis and Australopithecus afarensis.  

PubMed

Many researchers have suggested that Australopithecus anamensis and Australopithecus afarensis were among the earliest hominins to have diets that included hard, brittle items. Here we examine dental microwear textures of these hominins for evidence of this. The molars of three Au. anamensis and 19 Au. afarensis specimens examined preserve unobscured antemortem microwear. Microwear textures of these individuals closely resemble those of Paranthropus boisei, having lower complexity values than Australopithecus africanus and especially Paranthropus robustus. The microwear texture complexity values for Au. anamensis and Au. afarensis are similar to those of the grass-eating Theropithecus gelada and folivorous Alouatta palliata and Trachypithecus cristatus. This implies that these Au. anamensis and Au. afarensis individuals did not have diets dominated by hard, brittle foods shortly before their deaths. On the other hand, microwear texture anisotropy values for these taxa are lower on average than those of Theropithecus, Alouatta or Trachypithecus. This suggests that the fossil taxa did not have diets dominated by tough foods either, or if they did that directions of tooth-tooth movement were less constrained than in higher cusped and sharper crested extant primate grass eaters and folivores. PMID:20855308

Ungar, Peter S; Scott, Robert S; Grine, Frederick E; Teaford, Mark F

2010-10-27

422

Molar Cotton-Mouton constants and anisotropy of magnetic susceptibility of benzyl chlorides and benzyl bromides  

SciTech Connect

Based on an analysis of electrical and optical data, they previously established the steric structure of a series of benzyl halides and found that the polarizability ellipsoid of the aromatic nucleus undergoes significant rearrangement of its semiaxes in comparison to the semiaxes in toluene (I). In all of the systems examined the mobility of the electron cloud in the plane of the ring increases and decreases in the perpendicular direction. A conformation is realized in which the benzene ring is close to shielding of the C-H bond. Hyperconjugation of the ..pi..arom-sigmaC-Hal* type, particularly manifested in the nuclear quadrupole resonance spectra, is apparently responsible for the observed effects. The effect of similar interactions on the magnetic properties has not been studied either experimentally or theoretically. The anisotropies of magnetic susceptibility of molecules or groups of atoms can be calculated from the known optical polarizabilities using data on the magnetic birefringence constant (the Cotton-Mouton effect) of compounds in the form of vapors or solutions. The molar Cotton-Mouton constants of the title compounds were measured and the magnetic susceptibility ellipsoids (MSE) of the C/sub 6/H/sub 5/-C fragment in benzyl halides and (I), whose MSe is known, were comparatively estimated in the present study.

Vul'fson, S.G.; Dianova, O.M.; Vereshchagin, A.N.

1987-01-10

423

Subjective and objective evaluation of low-level laser therapy after molar extraction  

NASA Astrophysics Data System (ADS)

The aim of this study was to evaluate the different frequencies of low-level laser radiation on healing process after human molar extractions. Frequencies of 5 Hz, 292 Hz and 9000 Hz were used in experiments. Monitoring of secretory IgA and albumin level in saliva and changes in bone density were used as objective markers of biostimulatory effect. Subjective evaluation of therapy was observed using scale. Changes of sIgA, albumin levels and bone density were compared in group of 150 patients. Differences in levels of the saliva markers were found to be significant comparing irradiated and non-irradiated groups, as well as comparing groups irradiated by various modulatory frequencies. We observed significant differences between the increase of sIgA res. Albumin and subjective treatment feelings. Bone density after extraction and six-months after surgical treatment was examined using the dental digital radiovisiography. There were detected no significant differences between bone density in irradiated and non- irradiated groups perhaps due to our used therapy diagram.

Kucerova, Hana; Dostalova, Tatjana; Himmlova, Lucia; Bartova, Jirina; Mazanek, Jiri

2000-06-01

424

Coupled Nanomechanical and Raman Microspectroscopic Investigation of Human Third Molar DEJ  

PubMed Central

The dentino-enamel junction (DEJ) connects enamel, that covers the outer surface of a tooth, to a thicker underlying dentin. The DEJ is a critical interface that permits joining these materials that have widely dissimilar mechanical properties. AFM-based nanoindentation and Raman microspectroscopy were used to define the width and composition of human molar DEJ. Indentation elastic modulus and hardness of enamel, dentin, and DEJ were determined along lines of indents made at 2??m intervals across the DEJ. Indents made at maximum loads at each end of the indent lines were used to make visible markers allowing Raman microspectroscopy at 1??m intervals across the DEJ, while using the nanoindent markers for orientation and location. Functional DEJ width estimates were made based on results from nanoindentation and Raman microspectroscopy. DEJ width estimates ranged from 4.7 (±1.2) ?m to 6.1 (±1.9) ?m based on hardness and 4.9 (±1.1) ?m to 6.9 (±1.9) ?m based on modulus. DEJ width based on Raman peak intensity variations were 8.0 (±3.2) ?m to 8.5 (±3.1) ?m based on the phosphate peak, and 7.6 (±3.2) ?m to 8.0 (±2.6) ?m for C–H stretching mode. These estimates are in the range of DEJ width estimates reported using nanoindentation. PMID:20948572

Gallagher, R. R.; Balooch, M.; Balooch, G.; Wilson, R. S.; Marshall, S. J.; Marshall, G. W.

2010-01-01

425

Evaluation of dexamethasone for reduction of postsurgical sequelae of third molar removal.  

PubMed

Sixty patients with bilaterally symmetrical impacted third molars participated in this double-blind, within-subject study to quantify the effects of 4 mg of dexamethasone on reducing postsurgical sequelae. Each patient's surgery was staged by mouth side and completed in two appointments 5 to 6 weeks apart. A preoperative dose of dexamethasone given intravenously was randomized to mouth side and surgical appointment; sterile water served as a control. Major areas assessed in this study were facial swelling, pain, and trismus. No difference in swelling and daily pain was noted. However, trismus and global pain were significantly affected by the steroid. Patients had a daily postsurgical increase in incisal opening of 4 to 6 mm over the control side during the examination period. Patients evaluated pain by choosing the least painful side. By a greater than 4:1 margin, patients chose the steroid side as the least painful side. No increase in the rate or type of complications was detected between control and steroid sides. PMID:1403273

Neupert, E A; Lee, J W; Philput, C B; Gordon, J R

1992-11-01

426

76 FR 4601 - Determinations Concerning Need for Error Correction, Partial Approval and Partial Disapproval...  

Federal Register 2010, 2011, 2012, 2013

...Partial Approval and Partial Disapproval, and Federal...for Error Correction, Partial Approval and Partial Disappro