Radiographic assessment of lower third molar eruption in different anteroposterior skeletal patterns and age-related groups.

Science.gov (United States)

Jakovljevic, Aleksandar; Lazic, Emira; Soldatovic, Ivan; Nedeljkovic, Nenad; Andric, Miroslav

2015-07-01

To analyze radiographic predictors for lower third molar eruption among subjects with different anteroposterior skeletal relations and of different age groups. In total, 300 lower third molars were recorded on diagnostic digital orthopantomograms (DPTs) and lateral cephalograms (LCs). The radiographs were grouped according to sagittal intermaxillary angle (ANB), subject age, and level of lower third molar eruption. The DPT was used to analyze retromolar space, mesiodistal crown width, space/width ratio, third and second molar angulation (α, γ), third molar inclination (β), and gonion angle. The LC was used to determine ANB, angles of maxillar and mandibular prognathism (SNA, SNB), mandibular plane angle (SN/MP), and mandibular lengths. A logistic regression model was created using the statistically significant predictors. The logistic regression analysis revealed a statistically significant impact of β angle and distance between gonion and gnathion (Go-Gn) on the level of lower third molar eruption (P third molar impaction rate was significantly higher in the adult subgroup with the Class II (62.3%) compared with Class III subjects (31.7%; P third molar eruption were measured in Class III subjects. For valid estimation of mandibular third molar eruption, certain linear and angular measures (β angle, Go-Gn), as well as the size of the retromolar space, need to be considered.

Mercury and selenium in European catfish (Silurus glanis) from Northern Italian Rivers: can molar ratio be a predictive factor for mercury toxicity in a top predator?

Science.gov (United States)

Squadrone, S; Benedetto, A; Brizio, P; Prearo, M; Abete, M C

2015-01-01

The study of mercury and selenium bioaccumulation in fish is crucially important for evaluating the extent of contamination in freshwater environments, and the possible health risk posed for humans when the antagonistic interactions of these two elements are considered. Several factors affect the risk of mercury intake from fish consumption, including mercury levels, human consumption patterns, and sensitive populations (e.g., pregnant women, foetuses, young children and unknown genetic factors). The protective effects of selenium on mercury toxicity have been extensively publicised in recent years, particularly targeting fish consumers. In this study, mercury (Hg) and selenium (Se) concentrations were determined in the muscle of European catfish (Silurus glanis) collected from North Italian Rivers. Differences in mercury and selenium levels, as a function of size, gender and location were investigated. Hg was strongly related to length, gender and location, while Se levels are not dependent on fish size or location. The mean Se/Hg molar ratio was strongly affected by location, and significantly related to length and age. Selenium was in molar excess of mercury in all sites, with a rank order of mean Se/Hg molar ratio of the Parma River (2.55)>Po River (1.71)>Tanaro River (1.66)>Bormida River (1.36). However, in 37% of analyzed samples, Hg exceeded the maximum level set by 1881/2006/EC and 629/2008/EC in fish muscle. The molar ratio of Se/Hg was 0.5mg/kg), and therefore the mean molar ratio cannot be considered as a safety criterion in top predator fish. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mercury and selenium levels, and selenium:mercury molar ratios of brain, muscle and other tissues in bluefish (Pomatomus saltatrix) from New Jersey, USA

Science.gov (United States)

Burger, Joanna; Jeitner, Christian; Donio, Mark; Pittfield, Taryn; Gochfeld, Michael

2015-01-01

A number of contaminants affect fish health, including mercury and selenium, and the selenium: mercury molar ratio. Recently the protective effects of selenium on methylmercury toxicity have been publicized, particularly for consumption of saltwater fish. Yet the relative ameliorating effects of selenium on toxicity within fish have not been examined, nor has the molar ratio in different tissues, (i.e. brain). We examined mercury and selenium levels in brain, kidney, liver, red and white muscle, and skin and scales in bluefish (Pomatomus saltatrix) from New Jersey to determine whether there were toxic levels of either metal, and we computed the selenium: mercury molar ratios by tissues. Total mercury averaged 0.32 ± 0.02 ppm wet weight in edible muscle and 0.09 ± 0.01 ppm in brain. Selenium concentration averaged 0.37 ± 0.03 in muscle and 0.36 ± 0.03 ppm in brain. There were significant differences in levels of mercury, selenium, and selenium: mercury molar ratios, among tissues. Mercury and selenium levels were correlated in kidney and skin/scales. Mercury levels were highest in kidney, intermediate in muscle and liver, and lowest in brain and skin/scales; selenium levels were also highest in kidney, intermediate in liver, and were an order of magnitude lower in the white muscle and brain. Mercury levels in muscle, kidney and skin/scales were positively correlated with fish size (length). Selenium levels in muscle, kidney and liver were positively correlated with fish length, but in brain; selenium levels were negatively correlated with fish length. The selenium: mercury molar ratio was negatively correlated with fish length for white muscle, liver, kidney, and brain, particularly for fish over 50 cm in length, suggesting that older fish experience less protective advantages of selenium against mercury toxicity than smaller fish, and that consumers of bluefish similarly receive less advantage from eating larger fish. PMID:23202378

Influence of ZnO seed layer precursor molar ratio on the density of interface defects in low temperature aqueous chemically synthesized ZnO nanorods/GaN light-emitting diodes

Energy Technology Data Exchange (ETDEWEB)

Alnoor, Hatim, E-mail: hatim.alnoor@liu.se; Iandolo, Donata; Willander, Magnus; Nur, Omer [Department of Science and Technology (ITN), Linköping University, SE-601 74 Norrköping (Sweden); Pozina, Galia; Khranovskyy, Volodymyr; Liu, Xianjie [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-583 81 Linköping (Sweden)

2016-04-28

Low temperature aqueous chemical synthesis (LT-ACS) of zinc oxide (ZnO) nanorods (NRs) has been attracting considerable research interest due to its great potential in the development of light-emitting diodes (LEDs). The influence of the molar ratio of the zinc acetate (ZnAc): KOH as a ZnO seed layer precursor on the density of interface defects and hence the presence of non-radiative recombination centers in LT-ACS of ZnO NRs/GaN LEDs has been systematically investigated. The material quality of the as-prepared seed layer as quantitatively deduced by the X-ray photoelectron spectroscopy is found to be influenced by the molar ratio. It is revealed by spatially resolved cathodoluminescence that the seed layer molar ratio plays a significant role in the formation and the density of defects at the n-ZnO NRs/p-GaN heterostructure interface. Consequently, LED devices processed using ZnO NRs synthesized with molar ratio of 1:5 M exhibit stronger yellow emission (∼575 nm) compared to those based on 1:1 and 1:3 M ratios as measured by the electroluminescence. Furthermore, seed layer molar ratio shows a quantitative dependence of the non-radiative defect densities as deduced from light-output current characteristics analysis. These results have implications on the development of high-efficiency ZnO-based LEDs and may also be helpful in understanding the effects of the ZnO seed layer on defect-related non-radiative recombination.

Effect of Molecular Weight and Molar Ratio of Dextran on Self-Assembly of Dextran Stearate Polymeric Micelles as Nanocarriers for Etoposide

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Jaleh Varshosaz

2012-01-01

Full Text Available Amphiphilic polymer surfactants are composed of hydrophilic and hydrophobic polymers and are widely used in targeted drug delivery. The purpose of this study was the evaluation of the effect of molecular weight and molar ratio of dextran on physicochemical properties of dextran stearate polymeric micelles. Dextran stearate was synthesized by acylation of dextran with stearoyl chloride. Etoposide loaded polymeric micelles were prepared by dialysis method. The resulting micelles were evaluated for particle size, zeta potential, critical micelle concentration (CMC, drug loading capacity, and release efficiency. Cytotoxicity and cellular uptake of micelles were studied in CT-26 colorectal carcinoma cell line. Molecular weight and molar ratio of dextran-stearate were impressive on zeta potential, CMC, drug loading capacity, and release efficiency. Unlike polymer molecular weight, molar ratio of stearate had a significant effect on cytotoxicity and particle size of etoposide loaded micelles. Although molecular weight of dextran had no significant effect on cytotoxicity of micelles on CT-26 cells, it had drastic attributes for stability of polymeric micelles. Consequently, both variables of molecular weight of dextran and molar ratio of stearate should be taken into account to have a stable and effective micelle of dextran-stearate.

Cementoblastoma Relating to Right Mandibular Second Primary Molar

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Sivakumar Nuvvula

2016-01-01

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

Association between Peritonsillar Abscess and Molar Caries

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M Shayani Nasab

2006-05-01

Full Text Available Background: Peritonsillar abscess is the most common deep neck infections that are related with periodontal disease which has the same pathogenesis. We determined the relationship between peritonsillar infection and molar caries. Methods: In a cross-sectional study, 33 consecutive patients whom referred to Hamadan university clinic of otolaryngologic for peritonsillar abscess were examined by otolaryngologist and dentist who investigated relationship between peritonsillar infection and molar caries. Results: There were 27 males and 6 females with mean age 26.7+_7 years. The frequency caries on ipsilateral peritonsillar infection sides was in relation to molars caries on opposite sides (conterol group. This corrolation was significant with odds ratio 2.5. Conclusion: Molar caries were seen 2.5 times more likely to have peritonsillar infection compared with normal molar sides. Key Words: Peritonsillar abscess, Infection, Periodontal disease, Dental caries

Possible effects of insulin-like growth factor-I, IGF-binding protein-3 and IGF-1/IGFBP-3 molar ratio on mammographic density: a cross-sectional study.

Science.gov (United States)

Meggiorini, M L; Cipolla, V; Borgoni, G; Nofroni, I; Pala, A; de Felice, C

2012-01-01

The purpose of this study was to examine the possible effects of IGF-1, IGFBP-3 and IGF-1/IGFBP-3 molar ratio on mammographic density and assess whether this relationship was similar in subgroups of pre- and postmenopausal women. A group of 341 Italian women of childbearing age or naturally postmenopausal who had performed mammographic examination at the section of radiology of our department a maximum three months prior to recruitment were enrolled. A blood sample was drawn for determination of IGF-1, IGFBP-3 levels and IGF-1/IGFBP-3 molar ratio was calculated. On the basis of recent mammograms the women were divided into two groups: dense breast (DB) and non-dense breast (NDB). To assess the association between mammographic density and IGF-1, IGFBP-3 and Molar ratio Student's t-test was employed before and after stratified by menopausal status. The analysis of the relationship between mammographic density and plasma levels of IGF-1, IGFBP-3 and IGF-1/IGFBP-3 molar ratio showed that IGF-1 levels and molar ratio varied in the two groups resulting in higher mean values in the DB group whereas IGFBP-3 showed similar values in both groups (DB and NDB). After stratification of the study population by menopausal status, no association was found. Our study provides strong evidence of a crude association between breast density, and plasma levels of IGF-1 and molar ratio. IGF-1 and molar ratio might increase mammographic density and thus the risk of developing breast cancer.

Determination of Ca/P molar ratio in hydroxyapatite (HA) by X-ray fluorescence technique

International Nuclear Information System (INIS)

Scapin, Marcos A.; Guilhen, Sabine N.; Cotrim, Marycel E.B.; Pires, Maria Ap. F.

2015-01-01

Hydroxyapatite (HA) is a mineral composed of calcium phosphate employed for endodontics, restorative dentistry and other applications in orthopedics and prosthesis. Additionally, this biomaterial is an inexpensive but efficient adsorbent for the removal of heavy metals and other unwanted species of contaminated liquid effluents. This is especially interesting when low-cost effective remediation is required. A Ca / P molar ratio of 1.667 is consistent with the theoretical Ca / P ratio for calcium hydroxyapatite with a compositional formula of Ca 10 (PO 4 ) 6 (OH) 2 , which properties are well discussed in the literature. The aim of this work was to implement and validate a methodology for simultaneous determination of major and minor constituents in the hydroxyapatite (HA) as well as providing the Ca / P molar ratio. To accomplish these achievements, wavelength dispersive X-ray fluorescence spectroscopy (WDXRF) was applied. This is a non-destructive technique that requires no chemical treatment, enabling fast chemical analysis in a wide variety of samples, with no hazardous waste being generated as a result of the process of determination. A standard reference material from NIST (SRM 1400 – Bone Ash) was used to validate the methodology for the determination of magnesium, phosphorus, potassium, calcium, iron, zinc, strontium and the Ca / P ratio in HA samples by WDXRF. The Z-score test was applied as a statistical tool and showed that the calculated values were of less than 1.8 for all the measured analytes. (author)

Determination of Ca/P molar ratio in hydroxyapatite (HA) by X-ray fluorescence technique

Energy Technology Data Exchange (ETDEWEB)

Scapin, Marcos A.; Guilhen, Sabine N.; Cotrim, Marycel E.B.; Pires, Maria Ap. F., E-mail: mascapin@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2015-07-01

Hydroxyapatite (HA) is a mineral composed of calcium phosphate employed for endodontics, restorative dentistry and other applications in orthopedics and prosthesis. Additionally, this biomaterial is an inexpensive but efficient adsorbent for the removal of heavy metals and other unwanted species of contaminated liquid effluents. This is especially interesting when low-cost effective remediation is required. A Ca / P molar ratio of 1.667 is consistent with the theoretical Ca / P ratio for calcium hydroxyapatite with a compositional formula of Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}, which properties are well discussed in the literature. The aim of this work was to implement and validate a methodology for simultaneous determination of major and minor constituents in the hydroxyapatite (HA) as well as providing the Ca / P molar ratio. To accomplish these achievements, wavelength dispersive X-ray fluorescence spectroscopy (WDXRF) was applied. This is a non-destructive technique that requires no chemical treatment, enabling fast chemical analysis in a wide variety of samples, with no hazardous waste being generated as a result of the process of determination. A standard reference material from NIST (SRM 1400 – Bone Ash) was used to validate the methodology for the determination of magnesium, phosphorus, potassium, calcium, iron, zinc, strontium and the Ca / P ratio in HA samples by WDXRF. The Z-score test was applied as a statistical tool and showed that the calculated values were of less than 1.8 for all the measured analytes. (author)

Periodicity in the BrO/SO2 molar ratios in the volcanic gas plume of Cotopaxi and its correlation with the Earth tides during the eruption in 2015

Science.gov (United States)

Dinger, Florian; Bobrowski, Nicole; Warnach, Simon; Bredemeyer, Stefan; Hidalgo, Silvana; Arellano, Santiago; Galle, Bo; Platt, Ulrich; Wagner, Thomas

2018-03-01

We evaluated NOVAC (Network for Observation of Volcanic and Atmospheric Change) gas emission data from the 2015 eruption of the Cotopaxi volcano (Ecuador) for BrO/SO2 molar ratios. The BrO/SO2 molar ratios were very small prior to the phreatomagmatic explosions in August 2015, significantly higher after the explosions, and continuously increasing until the end of the unrest period in December 2015. These observations together with similar findings in previous studies at other volcanoes (Mt. Etna, Nevado del Ruiz, Tungurahua) suggest a possible link between a drop in BrO/SO2 and a future explosion. In addition, the observed relatively high BrO/SO2 molar ratios after December 2015 imply that bromine degassed predominately after sulfur from the magmatic melt. Furthermore, statistical analysis of the data revealed a conspicuous periodic pattern with a periodicity of about 2 weeks in a 3-month time series. While the time series is too short to rule out a chance recurrence of transient geological or meteorological events as a possible origin for the periodic signal, we nevertheless took this observation as a motivation to examine the influence of natural forcings with periodicities of around 2 weeks on volcanic gas emissions. One strong aspirant with such a periodicity are the Earth tides, which are thus central in this study. We present the BrO/SO2 data, analyse the reliability of the periodic signal, discuss a possible meteorological or eruption-induced origin of this signal, and compare the signal with the theoretical ground surface displacement pattern caused by the Earth tides. Our central result is the observation of a significant correlation between the BrO/SO2 molar ratios with the north-south and vertical components of the calculated tide-induced surface displacement with correlation coefficients of 47 and 36 %, respectively. From all other investigated parameters, only the correlation between the BrO/SO2 molar ratios and the relative humidity in the local

Adsorption of tetracycline on Fe (hydr)oxides: effects of pH and metal cation (Cu2+, Zn2+ and Al3+) addition in various molar ratios

Science.gov (United States)

Hsu, Liang-Ching; Liu, Yu-Ting; Syu, Chien-Hui; Huang, Mei-Hsia; Teah, Heng Yi

2018-01-01

Iron (Fe) (hydr)oxides control the mobility and bioavailability of tetracycline (TC) in waters and soils. Adsorption of TC on Fe (hydr)oxides is greatly affected by polyvalent metals; however, impacts of molar metal/TC ratios on TC adsorptive behaviours on Fe (hydr)oxides remain unclear. Results showed that maximum TC adsorption on ferrihydrite and goethite occurred at pH 5–6. Such TC adsorption was generally promoted by the addition of Cu2+, Zn2+ and Al3+. The greatest increase in TC adsorption was found in the system with molar Cu/TC ratio of 3 due to the formation of Fe hydr(oxide)–Cu–TC ternary complexes. Functional groups on TC that were responsible for the complexation with Cu2+shifted from phenolic diketone groups at Cu/TC molar ratio adsorption at a molar Al/TC ratio of 1. However, TC adsorption decreased for Al/TC molar ratio > 1 as excess Al3+ led to the competitive adsorption with Al/TC complexes. For the Zn2+ addition, no significant correlation was found between TC adsorption capacity and molar Zn/TC ratios. PMID:29657795

Co-relation of variables as determined from panoramic radiograph and evaluating their significance in eruption of permanent mandibular third molar

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Kushal Amin

2008-01-01

Full Text Available Purpose of the Study: Purpose of the study is to investigate whether the variables associated with the permanent mandibular third molar (PMM3 and arch dimensions could be co-related and significantly differentiated between a fully erupted and mesially impacted PMM3 among a set of Indian population. Study Design: A standardized panoramic radiograph was taken of subjects of age 21 years and above. Patients with missing tooth from mandibular arch, subjects undergoing or having history of orthodontic treatment, subjects having disto-angular, horizontal or vertical impacted PMM3 were excluded from the study. Subjects were divided into 2 groups: (1 mesially impacted PMM3 and (2 vertically erupted PMM3. Following measurements were taken from acetate paper tracing of standardized panoramic radiograph: (1 Angulation of long axis of PMM3 to permanent mandibular second molar (theta (2 Angulation of PMM 3 to base of mandible (theta 2 (3 Gonial angle (theta 3 (4 Mesio-distal width of PMM 3 (5 Retro molar space. From these measurements Ganss ratio (retro molar space /PMM3 crown width. was calculated. Results and Conclusion: Results revealed that angle theta 1, angle theta 2, retro molar space and Ganss ratio were positively co-related and highly significant variables associated with the mesially and vertically erupted teeth as measured on panoramic radiograph. Using these variables a long-term study can be carried out to predict the ultimate position of lower third molar in the arch so that if there is a probability of the tooth being impacted at a later age, a prophylactic germectomy can be performed at an early age.

Anomalous viscosity behavior of a bicelle system with various molar ratios of short-and long-chain phospholipids

International Nuclear Information System (INIS)

Hwang, Jimmy S.; Oweimreen, Ghassan A.

2003-01-01

Viscosity versus temperature curves were obtained for five DMPC/DHPC/H2O bilayer systems with DMPC/DHPC molar ratios of 3.2, 2.8, 2.5, 2.0 and 1.5. The curves showed the viscosity maxima that shifted to higher temperatures as the mole fraction of DHPC increased. The maxima are extremely high for the first three systems and are estimated to be no less than 600 Pa,s. The shift to higher temperature is explained in terms of decrease in the the coalescence of the bicells as the mole fraction of DHPC increases. The maxima are attributed to two competing effects; the normal decrease in viscosity with temperature is counterbalanced at low to moderate temperatures with an increase in viscosity resulting from coalescence. Such coalescence increases as the DMPC /DHPC molar ratio increases. (author)

Influence of S/Mn molar ratio on the morphology and optical property of γ-MnS thin films prepared by microwave hydrothermal

International Nuclear Information System (INIS)

Yu, Xin; Li-yun, Cao; Jian-feng, Huang; Jia, Liu; Jie, Fei; Chun-yan, Yao

2013-01-01

Highlights: ► The influence of the precursor solution molar ratio of S/Mn. ► The degree of orientation of the γ-MnS film decrease slightly with increasing the S/Mn from 2.0 to 4.0. ► Film quality is strongly affected by the initial nucleation. ► The absorption edge obviously shifts to a higher wavelength with the increase of the S/Mn molar ratio from 2.0 to 4.0. - Abstract: Well crystallized γ-MnS thin films were successfully synthesized at low temperature and short processing time via a novel microwave hydrothermal (M-H) process without any complexing agent by using manganese chloride and thioacetamide as source materials. The influence of different S/Mn molar ratio in the precursor solution on the phase compositions, morphologies and optical properties of the as-deposited films was investigated. The as-deposited γ-MnS thin films were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and ultraviolet–visible (UV–vis). Results show that the wurtzite phase γ-MnS thin films with good crystallization can be achieved when S/Mn molar ratio is controlled at 2.0–4.0. The deposited γ-MnS thin films exhibit (1 0 0) orientation growth with the thickness of 300–500 nm. With the increase of S/Mn molar ratio from 2.0 to 4.0, the orientation growth is weakened while the dense and uniform of the as-deposited γ-MnS thin films are obviously improved and the corresponding band gap of the thin films increase from 3.88 to 3.97 eV.

Decreased Serum IGF-1/IGFBP-3 Molar Ratio is Associated with Executive Function Behaviors in Type 2 Diabetic Patients with Mild Cognitive Impairment.

Science.gov (United States)

Huang, Rong; Wang, Pin; Han, Jing; Xia, Wenqing; Cai, Rongrong; Sun, Haixia; Sun, Jie; Wang, Shaohua

2015-01-01

Insulin-like growth factor (IGF)-1, through insulin/IGF-1 signaling pathway, is involved in the pathogenesis of type 2 diabetes mellitus (T2DM) and Alzheimer's disease. This study aimed to assess the association of serum IGF-1 and IGF binding protein (IGFBP)-3 levels with cognition status and to determine whether IGF-1 rs972936 polymorphism is associated with T2DM with mild cognitive impairment (MCI). A total of 150 T2DM patients, 75 satisfying the MCI diagnostic criteria and 75 exhibiting healthy cognition, were enrolled in this study. The cognitive function of the subjects was extensively assessed. Serum IGF-1 and IGFBP-3 levels were measured through enzyme-linked immunosorbent assay; IGF-1/IGFBP-3 molar ratio was calculated. Single nucleotide polymorphisms of the IGF-1-(rs972936) gene were analyzed. Serum IGF-1/IGFBP-3 molar ratio in MCI patients was significantly lower than that in the control group (p = 0.003). Significant negative correlations were found between IGF-1/IGFBP-3 molar ratio and Trail Making Test A and B (TMT-A and TMT-B) scores (p = 0.003; p function. Further multiple step-wise regression analysis revealed that the TMT-A or TMT-B score was significantly associated only with serum IGF-1/IGFBP-3 molar ratio (p = 0.016; p IGF-1 rs972936 polymorphism between MCI and control groups. A low serum IGF-1/IGFBP-3 molar ratio is associated with the pathogenesis of MCI, particularly executive function in T2DM populations. Further investigation with a large population size should be conducted to confirm this observed association.

Effect of Cu/In molar ratio on the microstructural and optical properties of microcrystalline CuInS2 prepared by solvothermal route

International Nuclear Information System (INIS)

Das, Kajari; Panda, Subhendu K.; Gorai, Soma; Mishra, Pratima; Chaudhuri, Subhadra

2008-01-01

Synthesis and characterization of CuInS 2 powder sample prepared by a simple and convenient solvothermal method is reported. The influence of the variation of Cu/In molar ratio from 0.69 to 1.25 on the particle morphology, crystal structure and optical properties of CuInS 2 samples was studied. The X-ray diffraction studies indicated that the samples were polycrystalline in nature. SEM images of the samples revealed that the copper-rich products were uniform microspheres with smooth surfaces, whereas microspheres formed by network of interconnected flakes were obtained for indium-rich products. The optical band gaps (E g ) of the products decreased from 1.60 to 1.43 eV with variation of Cu/In molar ratio. The variation of the Urbach tail width with Cu/In molar ratio indicated that the density of the defects is much higher for the indium-rich CuInS 2 , which was clearly revealed from Raman measurements

Periodicity in the BrO∕SO2 molar ratios in the volcanic gas plume of Cotopaxi and its correlation with the Earth tides during the eruption in 2015

Directory of Open Access Journals (Sweden)

F. Dinger

2018-03-01

Full Text Available We evaluated NOVAC (Network for Observation of Volcanic and Atmospheric Change gas emission data from the 2015 eruption of the Cotopaxi volcano (Ecuador for BrO∕SO2 molar ratios. The BrO∕SO2 molar ratios were very small prior to the phreatomagmatic explosions in August 2015, significantly higher after the explosions, and continuously increasing until the end of the unrest period in December 2015. These observations together with similar findings in previous studies at other volcanoes (Mt. Etna, Nevado del Ruiz, Tungurahua suggest a possible link between a drop in BrO∕SO2 and a future explosion. In addition, the observed relatively high BrO∕SO2 molar ratios after December 2015 imply that bromine degassed predominately after sulfur from the magmatic melt. Furthermore, statistical analysis of the data revealed a conspicuous periodic pattern with a periodicity of about 2 weeks in a 3-month time series. While the time series is too short to rule out a chance recurrence of transient geological or meteorological events as a possible origin for the periodic signal, we nevertheless took this observation as a motivation to examine the influence of natural forcings with periodicities of around 2 weeks on volcanic gas emissions. One strong aspirant with such a periodicity are the Earth tides, which are thus central in this study. We present the BrO∕SO2 data, analyse the reliability of the periodic signal, discuss a possible meteorological or eruption-induced origin of this signal, and compare the signal with the theoretical ground surface displacement pattern caused by the Earth tides. Our central result is the observation of a significant correlation between the BrO∕SO2 molar ratios with the north–south and vertical components of the calculated tide-induced surface displacement with correlation coefficients of 47 and 36 %, respectively. From all other investigated parameters, only the correlation between the BrO∕SO2 molar

A new method for the determination of the nitrogen content of nitrocellulose based on the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis

Energy Technology Data Exchange (ETDEWEB)

Alinat, Elodie, E-mail: elodie.alinat@chimie-paristech.fr [PSL Research University, Chimie ParisTech, Laboratory of Physicochemistry of Electrolytes, Colloids and Analytical Sciences (PECSA), 11 rue Pierre et Marie Curie, 75005 Paris (France); Central Laboratory of Police Prefecture (LCPP), 39 bis rue de Dantzig, 75015 Paris (France); CNRS, UMR 7195 PECSA, 11 rue Pierre et Marie Curie, 75005 Paris (France); Sorbonne Universités, UPMC Univ Paris 06, LBM, 4 place Jussieu, F-75005 Paris (France); Delaunay, Nathalie, E-mail: nathalie.delaunay@espci.fr [PSL Research University, Chimie ParisTech, Laboratory of Physicochemistry of Electrolytes, Colloids and Analytical Sciences (PECSA), 11 rue Pierre et Marie Curie, 75005 Paris (France); CNRS, UMR 7195 PECSA, 11 rue Pierre et Marie Curie, 75005 Paris (France); Sorbonne Universités, UPMC Univ Paris 06, LBM, 4 place Jussieu, F-75005 Paris (France); Archer, Xavier, E-mail: xavier.archer@interieur.gouv.fr [Central Laboratory of Police Prefecture (LCPP), 39 bis rue de Dantzig, 75015 Paris (France); Mallet, Jean-Maurice, E-mail: jean-maurice.mallet@es.fr [École Normale Supérieure-PSL Research University, Département de Chimie, 24 rue Lhomond, 75005 Paris (France); Sorbonne Universités, UPMC Univ Paris 06, LBM, 4 place Jussieu, F-75005 Paris (France); CNRS, UMR 7203 LBM, F-75005 Paris (France); Gareil, Pierre, E-mail: pierre.gareil@chimie-paristech.fr [PSL Research University, Chimie ParisTech, Laboratory of Physicochemistry of Electrolytes, Colloids and Analytical Sciences (PECSA), 11 rue Pierre et Marie Curie, 75005 Paris (France); CNRS, UMR 7195 PECSA, 11 rue Pierre et Marie Curie, 75005 Paris (France); Sorbonne Universités, UPMC Univ Paris 06, LBM, 4 place Jussieu, F-75005 Paris (France)

2015-04-09

Highlights: • New insights into the nitrocellulose alkaline denitration mechanism. • Linear correlation for molar ratio of nitrite-to-nitrate ions and nitrogen content. • Capillary electrophoresis monitoring of nitrite and nitrate ions. • Applications to explosive and non-explosive nitrocellulose-containing samples. • Improved performances (including safety) over classical methods. - Abstract: A new method was proposed to determine the nitrogen content of nitrocelluloses (NCs). It is based on the finding of a linear relationship between the nitrogen content and the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis. Capillary electrophoresis was used to monitor the concentration of nitrite and nitrate ions. The influences of hydrolysis time and molar mass of NC on the molar ratio of nitrite-to-nitrate ions were investigated, and new insights into the understanding of the alkaline denitration mechanism of NCs, underlying this analytical strategy is provided. The method was then tested successfully with various explosive and non-explosive NC-containing samples such as various daily products and smokeless gunpowders. Inherently to its principle exploiting a concentration ratio, this method shows very good repeatability in the determination of nitrogen content in real samples with relative standard deviation (n = 3) inferior to 1.5%, and also provides very significant advantages with respect to sample extraction, analysis time (1 h for alkaline hydrolysis, 3 min for electrophoretic separation), which was about 5 times shorter than for the classical Devarda's method, currently used in industry, and safety conditions (no need for preliminary drying NC samples, mild hydrolysis conditions with 1 M sodium hydroxide for 1 h at 60 °C)

A new method for the determination of the nitrogen content of nitrocellulose based on the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis

International Nuclear Information System (INIS)

Alinat, Elodie; Delaunay, Nathalie; Archer, Xavier; Mallet, Jean-Maurice; Gareil, Pierre

2015-01-01

Highlights: • New insights into the nitrocellulose alkaline denitration mechanism. • Linear correlation for molar ratio of nitrite-to-nitrate ions and nitrogen content. • Capillary electrophoresis monitoring of nitrite and nitrate ions. • Applications to explosive and non-explosive nitrocellulose-containing samples. • Improved performances (including safety) over classical methods. - Abstract: A new method was proposed to determine the nitrogen content of nitrocelluloses (NCs). It is based on the finding of a linear relationship between the nitrogen content and the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis. Capillary electrophoresis was used to monitor the concentration of nitrite and nitrate ions. The influences of hydrolysis time and molar mass of NC on the molar ratio of nitrite-to-nitrate ions were investigated, and new insights into the understanding of the alkaline denitration mechanism of NCs, underlying this analytical strategy is provided. The method was then tested successfully with various explosive and non-explosive NC-containing samples such as various daily products and smokeless gunpowders. Inherently to its principle exploiting a concentration ratio, this method shows very good repeatability in the determination of nitrogen content in real samples with relative standard deviation (n = 3) inferior to 1.5%, and also provides very significant advantages with respect to sample extraction, analysis time (1 h for alkaline hydrolysis, 3 min for electrophoretic separation), which was about 5 times shorter than for the classical Devarda's method, currently used in industry, and safety conditions (no need for preliminary drying NC samples, mild hydrolysis conditions with 1 M sodium hydroxide for 1 h at 60 °C)

Hypomineralized Second Primary Molars as Predictor of Molar Incisor Hypomineralization

Science.gov (United States)

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

2016-01-01

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

Co-production of acetone and ethanol with molar ratio control enables production of improved gasoline or jet fuel blends.

Science.gov (United States)

Baer, Zachary C; Bormann, Sebastian; Sreekumar, Sanil; Grippo, Adam; Toste, F Dean; Blanch, Harvey W; Clark, Douglas S

2016-10-01

The fermentation of simple sugars to ethanol has been the most successful biofuel process to displace fossil fuel consumption worldwide thus far. However, the physical properties of ethanol and automotive components limit its application in most cases to 10-15 vol% blends with conventional gasoline. Fermentative co-production of ethanol and acetone coupled with a catalytic alkylation reaction could enable the production of gasoline blendstocks enriched in higher-chain oxygenates. Here we demonstrate a synthetic pathway for the production of acetone through the mevalonate precursor hydroxymethylglutaryl-CoA. Expression of this pathway in various strains of Escherichia coli resulted in the co-production of acetone and ethanol. Metabolic engineering and control of the environmental conditions for microbial growth resulted in controllable acetone and ethanol production with ethanol:acetone molar ratios ranging from 0.7:1 to 10.0:1. Specifically, use of gluconic acid as a substrate increased production of acetone and balanced the redox state of the system, predictively reducing the molar ethanol:acetone ratio. Increases in ethanol production and the molar ethanol:acetone ratio were achieved by co-expression of the aldehyde/alcohol dehydrogenase (AdhE) from E. coli MG1655 and by co-expression of pyruvate decarboxylase (Pdc) and alcohol dehydrogenase (AdhB) from Z. mobilis. Controlling the fermentation aeration rate and pH in a bioreactor raised the acetone titer to 5.1 g L(-1) , similar to that obtained with wild-type Clostridium acetobutylicum. Optimizing the metabolic pathway, the selection of host strain, and the physiological conditions employed for host growth together improved acetone titers over 35-fold (0.14-5.1 g/L). Finally, chemical catalysis was used to upgrade the co-produced ethanol and acetone at both low and high molar ratios to higher-chain oxygenates for gasoline and jet fuel applications. Biotechnol. Bioeng. 2016;113: 2079-2087. © 2016 Wiley

The effect of Cu/Zn molar ratio on CO{sub 2} hydrogenation over Cu/ZnO/ZrO{sub 2}/Al{sub 2}O{sub 3} catalyst

Energy Technology Data Exchange (ETDEWEB)

Shaharun, Salina, E-mail: salinashaharun@gmail.com, E-mail: maizats@petronas.com.my; Shaharun, Maizatul S., E-mail: salinashaharun@gmail.com, E-mail: maizats@petronas.com.my; Taha, Mohd F., E-mail: faisalt@petronas.com.my [Department of Fundamental and Applied Science, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Mohamad, Dasmawati, E-mail: dasmawati@kck.usm.my [School of Dental Sciences, Health Campus, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia)

2014-10-24

Catalytic hydrogenation of carbon dioxide (CO{sub 2}) to methanol is an attractive way to recycle and utilize CO{sub 2}. A series of Cu/ZnO/Al{sub 2}O{sub 3}/ZrO{sub 2} catalysts (CZAZ) containing different molar ratios of Cu/Zn were prepared by the co-precipitation method and investigated in a stirred slurry autoclave system. The catalysts were characterized by temperature-programmed reduction (TPR), field emission scanning electron microscopy-energy dispersive analysis (FESEM-EDX), X-ray diffraction (XRD) and N{sub 2} adsorption-desorption. Higher surface area, SA{sub BET} values (42.6–59.9 m{sup 2}/g) are recorded at low (1) and high (5) Cu/Zn ratios with the minimum value of 35.71 m{sup 2}/g found for a Cu/Zn of 3. The reducibility of the metal oxides formed after calcination of catalyst samples was also affected due to change in metal-support interaction. At a low reaction temperature of 443 K, total gas pressure of 3.0 MPa and 0.1 g/mL of the CZAZ catalyst, the selectivity to methanol decreased as the Cu/Zn molar ratio increased, and the maximum selectivity of 67.73 was achieved at Cu/Zn molar ratio of 1. With a reaction time of 3h, the best performing catalyst was CZAZ75 with Cu/Zn molar ratio of 5 giving methanol yield of 79.30%.

Nutritional status and phytate:zinc and phytate x calcium:zinc dietary molar ratios of lacto-ovo vegetarian Trappist monks: 10 years later.

Science.gov (United States)

Harland, B F; Smith, S A; Howard, M P; Ellis, R; Smith, J C

1988-12-01

A nutrition assessment of 16 members of a community of lacto-ovo vegetarian Trappist monks was conducted in 1977. Plasma zinc was found to be low-normal, which was attributed primarily to high intakes of phytate-containing foods. Individual and group counseling were instituted over a 10-year period in an attempt to emphasize the importance of wise food selection within the constraints of lacto-ovo vegetarianism. In 1987, a more comprehensive nutrition assessment of 21 members of the same community was performed. Food composites were analyzed, and 3-day instead of 24-hour dietary records were kept. Intakes of phytate-containing foods had decreased from 4,569 to 972 mg/day; intake of dietary zinc had increased from 7.4 to 9.7 mg/day; and the phytate:zinc molar ratio had decreased from 67 to 14 for the years 1977 and 1987, respectively. An analyzed phytate:zinc molar ratio of 9.8 and an analyzed phytate x calcium:zinc molar ratio of 0.3 were representative of the 1987 community. Both were within normal ranges. Plasma zinc had risen to upper-normal levels. The 1987 nutrition assessment showed that it is possible to be adequately nourished with a lacto-ovo vegetarian diet provided one has proper knowledge of the phytate-containing foods and the methods for compensating with foods of greater mineral density (primarily zinc).

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

Science.gov (United States)

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

2015-02-01

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

Loss of the First Permanent Molar: Risk Factors and Adolescent Oral Health

Directory of Open Access Journals (Sweden)

Daraí Bárbara Sánchez Montero

2017-02-01

Full Text Available Foundation: the replacement of the primary dentition begins with the eruption of the first permanent molars that will be subjected to various risk factors.Objective: to determine the existing relation between the first permanent molar loss and the risk factors in adolescents from 12 to 14 years old. Method: a cross descriptive study was developed between October 20011 and March 2012. On a universe of 560 students, a simple random sampling was done and a sample of 185 patients was selected. On school visits dental exams were performed to determine the Clune index dental caries index, filled and missing teeth and the simplified index of oral hygiene. The estimated relative risk was used with prevalence odd ratio and prevalence ratio was calculated. The studied variables were: sex, oral hygiene habits, and habits of cariogenic diet bucodental health. Results: the loss of the first permanent molar predominated in the male sex with a 14.1 %. The prevailing risk factor was cariogenic diet which affected 57.3 of the population, where 80.6 of those who had a high consumption showed loss of the first permanent molar. Clune index (53,4 % in the female and 40 % in the male sex, dental caries, filled and lost teeth (1.7 % in female and 2.9 in the male sex were calculated. Conclusion: there is a direct relation between risk factors, poor oral hygiene and cariogenic feeding with the loss of the first permanent molar.

Influence of Zn/Fe Molar Ratio on Optical and Magnetic Properties of ZnO and ZnFe2O4 Nanocrystal as Calcined Products of Layered Double Hydroxides

Directory of Open Access Journals (Sweden)

Abdullah Ahmed Ali Ahmed

2014-01-01

Full Text Available The coprecipitation method has been used to synthesize layered double hydroxide (Zn-Fe-LDH nanostructure at different Zn2+/Fe3+ molar ratios. The structural properties of samples were studied using powder X-ray diffraction (PXRD. LDH samples were calcined at 600°C to produce mixed oxides (ZnO and ZnFe2O4. The crystallite size of mixed oxide was found in the nanometer scale (18.1 nm for ZnFe2O4 and 43.3 nm for ZnO. The photocatalytic activity of the calcination products was investigated using ultraviolet-visible-near infrared (UV-VIS-NIR diffuse reflectance spectroscopy. The magnetic properties of calcined LDHs were investigated using a vibrating sample magnetometer (VSM. The calcined samples showed a paramagnetic behavior for all Zn2+/Fe3+ molar ratios. The effect of molar ratio on magnetic susceptibility of the calcined samples was also studied.

A study on the determination of Ca/P molar ratio in calcium-hydroxyapatite by alpha excited x-ray fluorescence spectrometry

International Nuclear Information System (INIS)

Mizumoto, Yoshihiko; Iwata, Shiro.

1979-01-01

Nondestructive powdery calcium-hydroxyapatite (HAp) target was prepared by electrodeposition method. The powdery HAp was deposited on the copper electrode plate of cathode in the electrodeposition solution such as ethyl alcohol, methyl alcohol, etc. The experiments were carried out as functions of different electrodeposition solution, ethyl alcohol concentration, distance between anode and cathode, electrodeposition time and HAp amount added in bath, and distribution of HAp on the copper electrode plate obtained from each experiment was investigated by alpha excited X-ray fluorescence analysis. Ca/P molar ratio of thin HAp target prepared with this method was determined by alpha excited X-ray fluorescence spectrometry. The nondestructive HAp targets of thickness in the range of 5 mu g/cm 2 to 10 mg/cm 2 were easily prepared with comparatively simple apparatus. The HAp on the copper electrode plate was uniform thickness over 15 x 20 mm copper plate within 5%. The Ca/P molar ratio of HAp was 1.64 +- 0.05, which agreed well with stoichiometric value of 1.67 in HAp within standard deviation. (author)

Staging of third molar development in relation to chronological age of 5-16 year old Indian children.

Science.gov (United States)

Hegde, Sapna; Patodia, Akash; Dixit, Uma

2016-12-01

The usefulness of the developmental status of the third molar has been studied in assessment of the chronological age of adolescents in whom the development of the other permanent teeth is nearly complete. However, little is known about the timing and pattern of third-molar development in the Indian population. This study aimed to stage the third molar development in relation to chronological age of 5-16year old Indian children. In this cross-sectional observational study, the status of third molar development in relation to chronological age of 1139 Indian children aged 5-16 years was evaluated radiographically, using Orhan's modification of Demirjian's method. The frequency of occurrence of the third molars varied from 47% to 70%. Crypt formation, crown completion and root completion occurred as early as 5.4, 8.7 and 15.0 years, respectively. No significant differences based on gender or side were observed in third-molar development (p>0.05). For most stages, maxillary third molars were slightly more advanced than their mandibular counterparts (p>0.05). Considering the high degree of variability observed in third molar genesis and development, the usefulness of this tooth in age determination studies may be very limited in the age group studied. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Continuous production of biofuel from refined and used palm olein oil with supercritical methanol at a low molar ratio

International Nuclear Information System (INIS)

Sakdasri, Winatta; Sawangkeaw, Ruengwit; Ngamprasertsith, Somkiat

2015-01-01

Highlights: • Continuous production of biofuel in SCM at low molar ratio was studied. • The actual density of mixture was applied to calculate residence times. • The maximum FAME of 80–90% was observed for refined and used palm oils. • The glycerol–methanol reaction showed a positive effect in fuel yield. - Abstract: The high energy consumption and high environmental impact in the supercritical methanol (SCM) process primarily originates from the preheating of reactants and the recovery of excess alcohols. This work demonstrated the synthesis of biofuel using a lowered methanol to oil molar ratio of 12:1, instead of the 40:1–42:1 ratios that are commonly employed in conventional SCM. The apparent density of the reacting mixture was measured and applied to accurately calculate residence times in a continuous reactor. The effects of residence time were considered from 10 to 25 min. The results revealed that excessive residence times reduced the ester content, especially for unsaturated esters, in the resulting biofuel. A residence time of 20 min was recommended to simultaneously achieve a maximum ester content of 90% and a triglyceride conversion of up to 99%. Used palm olein oil with high free fatty acid (4.56 wt.%) can be employed as a feedstock and give a maximum ester content of 80%. In addition, the side reaction between glycerol and methanol at 400 °C and 15 MPa showed a positive effect in increasing fuel yield by 2%–7%

Image analysis of the eruptive positions of third molars and adjacent second molars as indicators of age evaluation in Thai patients.

Science.gov (United States)

Mahasantipiya, Phattaranant May; Pramojanee, Sakarat; Thaiupathump, Trasapong

2013-12-01

This study was performed to determine the relationship between the stage of tooth eruption (both vertical and mesio-angular) and chronological age. Indirect digital panoramic radiographs were used to measure the distances from the dentinoenamel junction (DEJ) of the second molars to the occlusal plane of the second molar teeth and of the adjacent third molars in 264 Thai males and 437 Thai females using ImageJ software. The ratio of those distances was calculated by patient age, and the correlation coefficient of the ratio of the third molar length to the second molar length was calculated. The correlation between the height of the vertically erupted upper third molar teeth and age was at the intermediate level. The age range of ≥15 to age determined from the eruptional height and actual chronological age was statistically significant. The mean age of the female subjects, in which the position of the right upper third molar teeth was at or above the DEJ of the adjacent second molar but below one half of its coronal height was 19.9±2.6 years. That for the left side was 20.2±2.7 years. The mean ages of the male subjects were 20.1±3.3 years and 19.8±2.7 years for the right and left sides, respectively. It might be possible to predict chronological age from the eruption height of the wisdom teeth.

Molar volume of eutectic solvents as a function of molar composition and temperature☆

Institute of Scientific and Technical Information of China (English)

Farouq S. Mjalli

2016-01-01

The conventional Rackett model for predicting liquid molar volume has been modified to cater for the effect of molar composition of the Deep Eutectic Solvents (DES). The experimental molar volume data for a group of commonly used DES has been used for optimizing the improved model. The data involved different molar compositions of each DES. The validation of the new model was performed on another set of DESs. The average relative deviation of the model on the training and validation datasets was approximately 0.1%while the Rackett model gave a relative deviation of more than 1.6%. The modified model deals with variations in DES molar com-position and temperature in a more consistent way than the original Rackett model which exhibits monotonic performance degradation as temperature moves away from reference conditions. Having the composition of the DES as a model variable enhances the practical utilization of the predicting model in diverse design and process simulation applications.

Phytate/calcium molar ratio does not predict accessibility of calcium in ready-to-eat dishes.

Science.gov (United States)

Erba, Daniela; Manini, Federica; Meroni, Erika; Casiraghi, Maria C

2017-08-01

Phytic acid (PA), a naturally occurring compound of plant food, is generally considered to affect mineral bioavailability. The aim of this study was to investigate the reliability of the PA/calcium molar ratio as a predictive factor of calcium accessibility in composed dishes and their ingredients. Dishes were chosen whose ingredients were rich in Ca (milk or cheese) or in PA (whole-wheat cereals) in order to consider a range of PA/Ca ratios (from 0 to 2.4) and measure Ca solubility using an in vitro approach. The amounts of soluble Ca in composed dishes were consistent with the sum of soluble Ca from ingredients (three out of five meals) or higher. Among whole-wheat products, bread showed higher Ca accessibility (71%, PA/Ca = 1.1) than biscuits (23%, PA/Ca = 0.9) and pasta (15%, PA/Ca = 1.5), and among Ca-rich ingredients, semi-skimmed milk displayed higher Ca accessibility (64%) than sliced cheese (50%) and Parmesan (38%). No significant correlation between the PA/Ca ratio and Ca accessibility was found (P = 0.077). The reliability of the PA/Ca ratio for predicting the availability of calcium in composed dishes is unsatisfactory; data emphasized the importance of the overall food matrix influence on mineral accessibility. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Evaluation of third molar development and its relation to chronological age: a panoramic radiographic study.

Science.gov (United States)

Zandi, Mohammad; Shokri, Abbas; Malekzadeh, Hamid; Amini, Payam; Shafiey, Parastu

2015-06-01

Third molar development, in comparison to other teeth in the dentition, has the greatest variation in morphology, anatomical position, and time of development and eruption, and its reliability for chronological age estimation is controversial. The aim of the present study was to evaluate third molar development and its relation to chronological age using panoramic radiography. A total of 2536 digital panoramic radiographs of individuals aged between 5 and 26 years were selected. The developmental status of the third molars was assessed using eight-stage developmental scoring proposed by Demirjian et al., with one modification: a stage 0 was added. The collected data were entered into a checklist and subjected to statistical analyses. The mean ages of the first appearance of third molar bud, complete crown formation, and root apex closure were around 9, 14, and 22 years, respectively. In both jaws, third molar development occurred symmetrically, and sexual dimorphism was observed at some developmental stages. Finally, two formulas were presented to estimate age of the juveniles and adolescents based on their gender and developmental stages of the third molars, and validated on a second sample consisting of 523 individuals aged between 8 and 22. Assessment of third molar development was found to be a reliable method for age estimation of individuals between 11 and 22 years. Because of possible ethnic and geographic differences in third molar development, population specific researches were recommended.

Molar ratios of therapeutic water-soluble phenothiazine⋅water-insoluble phospholipid adducts reveal a Fibonacci correlation and a putative link for structure–activity relationships

DEFF Research Database (Denmark)

Keyzer, Hendrik; Fey, S. J.; Thornton, Barry

2015-01-01

1,2diacyl-sn-glycero-3-phospholipids (PL) with even-numbered symmetric saturated diacyl chains with the headgroups choline (PC), glycerol (PG), serine (PS), ethanolamine (PE), phosphatidic acid (PA). We observed water soluble products with replicable molar ratios (MR) that could be divided into two...

Image analysis of the eruptive positions of third molars and adjacent second molars as indicators of age evaluation in Thai patients

Energy Technology Data Exchange (ETDEWEB)

Mahasantipiya, Phattaranant May; Pramojanee, Sakarat; Thaiupathump, Trasapong [Chiang Mai University, Chiang Mai (Thailand)

2013-12-15

This study was performed to determine the relationship between the stage of tooth eruption (both vertical and mesio-angular) and chronological age. Indirect digital panoramic radiographs were used to measure the distances from the dentinoenamel junction (DEJ) of the second molars to the occlusal plane of the second molar teeth and of the adjacent third molars in 264 Thai males and 437 Thai females using ImageJ software. The ratio of those distances was calculated by patient age, and the correlation coefficient of the ratio of the third molar length to the second molar length was calculated. The correlation between the height of the vertically erupted upper third molar teeth and age was at the intermediate level. The age range of ≥15 to <16 years was noted to be the range in which the correlation between the chronological age determined from the eruptional height and actual chronological age was statistically significant. The mean age of the female subjects, in which the position of the right upper third molar teeth was at or above the DEJ of the adjacent second molar but below one half of its coronal height was 19.9±2.6 years. That for the left side was 20.2±2.7 years. The mean ages of the male subjects were 20.1±3.3 years and 19.8±2.7 years for the right and left sides, respectively. It might be possible to predict chronological age from the eruption height of the wisdom teeth.

Image analysis of the eruptive positions of third molars and adjacent second molars as indicators of age evaluation in Thai patients

International Nuclear Information System (INIS)

Mahasantipiya, Phattaranant May; Pramojanee, Sakarat; Thaiupathump, Trasapong

2013-01-01

This study was performed to determine the relationship between the stage of tooth eruption (both vertical and mesio-angular) and chronological age. Indirect digital panoramic radiographs were used to measure the distances from the dentinoenamel junction (DEJ) of the second molars to the occlusal plane of the second molar teeth and of the adjacent third molars in 264 Thai males and 437 Thai females using ImageJ software. The ratio of those distances was calculated by patient age, and the correlation coefficient of the ratio of the third molar length to the second molar length was calculated. The correlation between the height of the vertically erupted upper third molar teeth and age was at the intermediate level. The age range of ≥15 to <16 years was noted to be the range in which the correlation between the chronological age determined from the eruptional height and actual chronological age was statistically significant. The mean age of the female subjects, in which the position of the right upper third molar teeth was at or above the DEJ of the adjacent second molar but below one half of its coronal height was 19.9±2.6 years. That for the left side was 20.2±2.7 years. The mean ages of the male subjects were 20.1±3.3 years and 19.8±2.7 years for the right and left sides, respectively. It might be possible to predict chronological age from the eruption height of the wisdom teeth.

Morphology evolution of gold nanoparticles as function of time, temperature, and Au(III)/sodium ascorbate molar ratio

Energy Technology Data Exchange (ETDEWEB)

Priolisi, Ornella, E-mail: ornella.priolisi@depretto.gov.it [ITIS “De Pretto” (Italy); Fabrizi, Alberto, E-mail: fabrizi@gest.unipd.it [University of Padova, Department of Management and Engineering (Italy); Deon, Giovanna, E-mail: giovanna.deon@depretto-vi.it [ITIS “De Pretto” (Italy); Bonollo, Franco, E-mail: bonollo@gest.unipd.it [University of Padova, Department of Management and Engineering (Italy); Cattini, Stefano, E-mail: stefano.cattini@unimore.it [University of Modena and Reggio Emilia, Department of Engineering Enzo Ferrari (Italy)

2016-01-15

In this work the morphology evolution of Au nanoparticles (AuNPs), obtained by direct reduction, was studied as a function of time, temperature, and Au(III)/sodium ascorbate molar ratio. The NPs morphology was examined by transmission electron microscope with image analysis, while time evolution was investigated by visible and near-infrared absorption spectroscopy and dynamic light scattering. It is found that initially formed star-like NPs transform in more spheroidal particles and the evolution appears more rapid by increasing the temperature while a large amount of reducing agent prevents the remodeling of AuNPs. An explication of morphology evolution is proposed.

Effect of NH4-N/P and Ca/P molar ratios on the reactive crystallization of calcium phosphates for phosphorus recovery from wastewater

DEFF Research Database (Denmark)

Vasenko, Liubov; Qu, Haiyan

2017-01-01

In this work, the effects of operational parameters, initial phosphorus concentration and molar ratios of Ca/P and NH4-N/P (further in the text N/P), on the nature and purity of precipitated phosphorus products have been investigated in an artificial system that mimics the supernatant in wastewater...

Optimization of NaOH Molarity, LUSI Mud/Alkaline Activator, and Na2SiO3/NaOH Ratio to Produce Lightweight Aggregate-Based Geopolymer

Directory of Open Access Journals (Sweden)

Rafiza Abdul Razak

2015-05-01

Full Text Available This paper presents the mechanical function and characterization of an artificial lightweight geopolymer aggregate (ALGA using LUSI (Sidoarjo mud and alkaline activator as source materials. LUSI stands for LU-Lumpur and SI-Sidoarjo, meaning mud from Sidoarjo which erupted near the Banjarpanji-1 exploration well in Sidoarjo, East Java, Indonesia on 27 May 2006. The effect of NaOH molarity, LUSI mud/Alkaline activator (LM/AA ratio, and Na2SiO3/NaOH ratio to the ALGA are investigated at a sintering temperature of 950 °C. The results show that the optimum NaOH molarity found in this study is 12 M due to the highest strength (lowest AIV value of 15.79% with lower water absorption and specific gravity. The optimum LUSI mud/Alkaline activator (LM/AA ratio of 1.7 and the Na2SiO3/NaOH ratio of 0.4 gives the highest strength with AIV value of 15.42% with specific gravity of 1.10 g/cm3 and water absorption of 4.7%. The major synthesized crystalline phases were identified as sodalite, quartz and albite. Scanning Electron Microscope (SEM image showed more complete geopolymer matrix which contributes to highest strength of ALGA produced.

Optimization of NaOH Molarity, LUSI Mud/Alkaline Activator, and Na2SiO3/NaOH Ratio to Produce Lightweight Aggregate-Based Geopolymer

Science.gov (United States)

Abdul Razak, Rafiza; Abdullah, Mohd Mustafa Al Bakri; Hussin, Kamarudin; Ismail, Khairul Nizar; Hardjito, Djwantoro; Yahya, Zarina

2015-01-01

This paper presents the mechanical function and characterization of an artificial lightweight geopolymer aggregate (ALGA) using LUSI (Sidoarjo mud) and alkaline activator as source materials. LUSI stands for LU-Lumpur and SI-Sidoarjo, meaning mud from Sidoarjo which erupted near the Banjarpanji-1 exploration well in Sidoarjo, East Java, Indonesia on 27 May 2006. The effect of NaOH molarity, LUSI mud/Alkaline activator (LM/AA) ratio, and Na2SiO3/NaOH ratio to the ALGA are investigated at a sintering temperature of 950 °C. The results show that the optimum NaOH molarity found in this study is 12 M due to the highest strength (lowest AIV value) of 15.79% with lower water absorption and specific gravity. The optimum LUSI mud/Alkaline activator (LM/AA) ratio of 1.7 and the Na2SiO3/NaOH ratio of 0.4 gives the highest strength with AIV value of 15.42% with specific gravity of 1.10 g/cm3 and water absorption of 4.7%. The major synthesized crystalline phases were identified as sodalite, quartz and albite. Scanning Electron Microscope (SEM) image showed more complete geopolymer matrix which contributes to highest strength of ALGA produced. PMID:26006238

Middle mesial canals in mandibular molars: incidence and related factors.

Science.gov (United States)

Nosrat, Ali; Deschenes, Raney J; Tordik, Patricia A; Hicks, M Lamar; Fouad, Ashraf F

2015-01-01

Although the internal anatomy of mandibular molars has been extensively studied, information about middle mesial (MM) canals is limited. The primary aim of this retrospective study was to evaluate the incidence of MM canals in mandibular first and second molars. The secondary aim was to correlate the incidence of MM canals with variables of molar type, sex, age, ethnicity, and presence of a second distal canal. All mature permanent first and second mandibular molars treated from August 2012 to May 2014 were included in the analysis. After completion of root canal instrumentation in all main canals, the clinician inspected the isthmus area of the mesial root using the dental operating microscope. If there was a catch point in this area with a file or explorer, the operator spent more time attempting to negotiate an MM canal. Seventy-five mandibular first and second molars were treated during the specified period. Fifteen (20%) teeth had negotiable MM canals. The incidence of MM canals was 32.1% in patients ≤ 20 years old, 23.8% in patients 21-40 years old, and 3.8% in patients > 40 years. Analysis of data revealed a significant difference in the distribution of MM canals among different age groups (P molar type, and presence of a second distal canal were not significant. The incidence of negotiable MM canals overall and their frequency of identification in younger patients were higher than in previous reports. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Prosthodontic decision-making relating to dentitions with compromised molars: the perspective of Swedish General Dental Practitioners.

Science.gov (United States)

Korduner, E-K; Collin Bagewitz, I; Vult von Steyern, P; Wolf, E

2016-12-01

The aim of this investigation was to study the clinical prosthodontic decision-making process relating to dentitions with compromised molars among Swedish general dental practitioners (GDPs). Eleven Swedish GDPs were purposively selected, and all agreed to participate. Then, in-depth, semi-structured interviews were conducted and covered treatment considerations concerning two authentic patient cases, initially with complete dental arches, and later, a final treatment based on a shortened dental arch (SDA) was discussed. The cases involved patients with compromised teeth situated mainly in the molar regions. One patient suffered from extensive caries and the other from severe periodontal disease. Qualitative content analysis was used to analyse the data. In the systematic analysis, two main categories were identified: holistic and functional approach. Among the interviewed GDPs, focus was put on patients' needs, background history and motivation for treatment as well as the preservation of molar support. Within the limitations of this study, the following can be concluded: keeping a dental arch with molars seems to be important to Swedish general dental practitioners. The SDA concept does not seem to have a substantial impact on the prosthodontic decision-making relating to dentitions with compromised molars. The dentist's experiences, as well as colleagues' or consulting specialist advice together with aetiological factors and the patient's individual situation, influence the decision-making more than the SDA concept. The conflicting results in the prosthetic decision-making process concerning the relevance of age and the need for molar support need further investigation, for example based on decisions made in the dentist's own clinical practice. © 2016 John Wiley & Sons Ltd.

An innovative technique to distalize maxillary molar using microimplant supported rapid molar distalizer

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Meenu Goel

2013-01-01

Full Text Available Introduction: In recent years, enhancements in implants have made their use possible as a mode of absolute anchorage in orthodontic patients. In this paper, the authors have introduced an innovative technique to unilaterally distalize the upper left 1 st molar to obtain an ideal Class I molar relationship from a Class II existing molar relationship with an indigenous designed distalizer. Clinical Innovation: For effective unilateral diatalization of molar, a novel cantilever sliding jig assembly was utilized with coil spring supported by a buccally placed single micro implant. The results showed 3 mm of bodily distalization with 1 mm of intrusion and 2° of distal tipping of upper left 1 st molar in 1.5 months. Discussion: This appliance is relatively easy to insert, well-tolerated, and requires minimal patient cooperation compared to other present techniques of molar distalization. Moreover, it is particularly useful in cases that are Class II on one side and Class I on the other, with a minor midline discrepancy and nominal overjet. Patient acceptance level was reported to be within patients physiological and comfort limits.

Deciduous molar hypomineralization and molar incisor hypomineralization

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

2012-01-01

This study was embedded in the Generation R Study, a population-based prospective cohort study from fetal life until young adulthood. This study focused on the relationship between Deciduous Molar Hypomineralization (DMH) and Molar Incisor Hypomineralization (MIH). First permanent molars develop

Effect of ammonium carbonate to metal ions molar ratio on synthesis and sintering of Nd:YAG nanopowders

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Liu, Qiang; Chen, Cong; Dai, Jiawei; Hu, Zewang; Chen, Haohong; Li, Jiang

2018-06-01

Using the nanopowders synthesized by a reverse co-precipitation method, neodymium doped yttrium aluminum garnet (Nd:YAG) transparent ceramics were fabricated by vacuum sintering method. The influence of ammonium carbonate to metal ions (NH4HCO3/M3+) molar ratio (R value) on the properties of Nd:YAG precursors and powders, as well as the densification, microstructure, and transmittance of the resultant ceramics was systematically investigated. The results show that the precursors have similar compositions and the calcined powders have pure Y3Al5O12 (YAG) phase. However, the R value is closely related to the morphologies of the precursors and powders. It is found that the powder with R = 3.0 has strongest agglomeration and the powders with R = 3.2-4.0 show better dispersity. Using these powders as starting materials, the corresponding ceramics were sintered at 1720 °C for 20 h in vacuum. As a result, the ceramic with R = 3.2 obtains the best transmittance of about 72% at the wavelength of 1064 nm. The grain growth exponent and activation energy of the Nd:YAG ceramics fabricated from the powder with R = 3.2 were also studied.

Maxillary molar distalization with first class appliance.

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

2014-02-27

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

Bioactivity tests of calcium phosphates with variant molar ratios of main components.

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Pluta, Klaudia; Sobczak-Kupiec, Agnieszka; Półtorak, Olga; Malina, Dagmara; Tyliszczak, Bożena

2018-03-09

Calcium phosphates constitute attractive materials of biomedical applications. Among them particular attention is devoted to bioactive hydroxyapatite (HAp) and bioresorbable tricalcium phosphate (TCP) that possess ability to bind to living bones and can be used clinically as important bone substitutes. Notably, in vivo bone bioactivity can be predicted from apatite formation of bone immersed in SBF fluids. Thus, analyses of behavior of calcium phosphates immersed in various bio fluids are of great importance. Recently, stoichiometric HAp and TCP structures have been widely studied, whereas only limited number of publications have been devoted to analyses of nonstoichiometric calcium phosphates. Here, we report physicochemical analysis of natural and synthetic phosphates with variable Ca/P molar ratios. Subsequently attained structures were subjected to incubation in either artificial saliva or Ringer's fluids. Both pH and conductivity of such fluids were determined before and after incubation. Furthermore, the influence of the Ca/P values on such parameters was exemplified. Physicochemical analysis of received materials was performed by XRD and FT-IR characterization techniques. Their potential antibacterial activity and behavior in the presence of infectious microorganisms as Escherichia coli and Staphylococcus aureus was also evaluated. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2018. © 2018 Wiley Periodicals, Inc.

Adhesives for bonded molar tubes during fixed brace treatment.

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Millett, Declan T; Mandall, Nicky A; Mattick, Rye Cr; Hickman, Joy; Glenny, Anne-Marie

2017-02-23

Orthodontic treatment involves using fixed or removable appliances (dental braces) to correct the positions of teeth. The success of a fixed appliance depends partly on the metal attachments (brackets and bands) being glued to the teeth so that they do not become detached during treatment. Brackets (metal squares) are usually attached to teeth other than molars, where bands (metal rings that go round each tooth) are more commonly used. Orthodontic tubes (stainless steel tubes that allow wires to pass through them), are typically welded to bands but they may also be glued directly (bonded) to molars. Failure of brackets, bands and bonded molar tubes slows down the progress of treatment with a fixed appliance. It can also be costly in terms of clinical time, materials and time lost from education/work for the patient. This is an update of the Cochrane review first published in 2011. A new full search was conducted on 15 February 2017 but no new studies were identified. We have only updated the search methods section in this new version. The conclusions of this Cochrane review remain the same. To evaluate the effectiveness of the adhesives used to attach bonded molar tubes, and the relative effectiveness of the adhesives used to attach bonded molar tubes versus adhesives used to attach bands, during fixed appliance treatment, in terms of: (1) how often the tubes (or bands) come off during treatment; and (2) whether they protect the bonded (or banded) teeth against decay. The following electronic databases were searched: Cochrane Oral Health's Trials Register (to 15 February 2017), the Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 1) in the Cochrane Library (searched 15 February 2017), MEDLINE Ovid (1946 to 15 February 2017), and Embase Ovid (1980 to 15 February 2017). We searched ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform for ongoing trials. No restrictions were placed on the language or

Molar Pregnancy

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... weeks of pregnancy Ovarian cysts Anemia Overactive thyroid (hyperthyroidism) Causes A molar pregnancy is caused by an ... have this complication than a partial molar pregnancy. Prevention If you've had a molar pregnancy, talk ...

Theoretical insight into the binding energy and detonation performance of ε-, γ-, β-CL-20 cocrystals with β-HMX, FOX-7, and DMF in different molar ratios, as well as electrostatic potential.

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Feng, Rui-Zhi; Zhang, Shu-Hai; Ren, Fu-de; Gou, Rui-Jun; Gao, Li

2016-06-01

Molecular dynamics method was employed to study the binding energies on the selected crystal planes of the ε-, γ-, β-conformation 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (ε-, γ-, β-CL-20) cocrystal explosives with 1,1-diamino-2,2-dinitroethylene (FOX-7), 1,3,5,7-tetranitro- 1,3,5,7-tetrazacyclooctane with β-conformation (β-HMX) and N,N-dimethylformamide (DMF) in different molar ratios. The oxygen balance, density, detonation velocity, detonation pressure, and surface electrostatic potential were analyzed. The results indicate that the binding energies E b (*) and stabilities are in the order of 1:1 > 2:1 > 3:1 > 5:1 > 8:1 (CL-20:FOX-7/β-HMX/DMF). The values of E b (*) and stabilities of the energetic-nonenergetic CL-20/DMF cocrystals are far larger than those of the energetic-energetic CL-20/FOX-7 and CL-20/β-HMX, and those of CL-20/β-HMX are the smallest. For CL-20/FOX-7 and CL-20/β-HMX, the largest E b (*) appears in the cocrystals with the 1:1, 1:2 or 1:3 molar ratio, and the stabilities of the cocrystals with the excess ratio of CL-20 are weaker than those in the cocrystals with the excess ratio of FOX-7 or β-HMX. In CL-20/FOX-7, CL-20 prefers adopting the γ-form, and ε-CL-20 is the preference in CL-20/β-HMX, and ε-CL-20 and β-CL-20 can be found in CL-20/DMF. The CL-20/FOX-7 and CL-20/β-HMX cocrystals with low molar ratios can meet the requirements of low sensitive high energetic materials. Surface electrostatic potential reveals the nature of the sensitivity change upon the cocrystal formation. Graphical Abstract MD method was employed to study the binding energies on the selected crystal planes in the ε-, γ-, β-CL-20 cocrystals with FOX-7, β-HMX and DMF in different molar ratios. Surface electrostatic potential reveals the nature of the sensitivity change in cocrystals.

Radiologic study of mandibular third molar of Korean youths

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Ahn, Hyung Kyu

1982-01-01

The author has made a study on the classification of the mandibular 3rd molars of Korean youths through dental radiography by means of Pell and Gregory's classification and on the prevalence of the dental caries of distal surface of the mandibular 2nd molar adjacent to the mandibular 3rd molars turned anteriorly. The results are as follow; 1. It was found that the largest case number was class I (272 cases, 52.9%) in the relation of the tooth to the ramus of the mandible and 2nd molar. 2. The mesio-angular position was the largest number (239 cases, 46.5%) in the relation of the long axis of the impacted mandibular 3rd molar to the long axis of the 2nd molar. 3. The mesio-angular position of class I was the largest number (140 cases, 27.2%) in the relation of the tooth to the ramus of the mandible and 2nd molar and the long axis of the impacted mandibular 3rd moral to the long axis of the 2nd molar. 4. The average angle of the long axis of mandibular 3rd molar in mesioangular position or horizontal position to the occlusal plane was 143 W 5. Mandibular 3rd molar with lesion such as dental cries or pericoronitis was 73 cases (14.2). 6. The caries incidence rate of the distal surface of the 2nd molar was about 3.1%.

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

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

2012-11-01

In the subadult age group, third molar development, as well as age-related morphological tooth information can be observed on panoramic radiographs. The aim of present study was to combine, in subadults, panoramic radiographic data based on developmental stages of third molar(s) and morphological measurements from permanent teeth, in order to evaluate its added age-predicting performances. In the age range between 15 and 23 years, 25 gender-specific radiographs were collected within each age category of 1 year. Third molar development was classified and registered according the 10-point staging and scoring technique proposed by Gleiser and Hunt (1955), modified by Köhler (1994). The Kvaal (1995) measuring technique was applied on the indicated teeth from the individuals' left side. Linear regression models with age as response and third molar-scored stages as explanatory variables were developed, and morphological measurements from permanent teeth were added. From the models, determination coefficients (R (2)) and root-mean-square errors (RMSE) were calculated. Maximal-added age information was reported as a 6 % R² increase and a 0.10-year decrease of RMSE. Forensic dental age estimations on panoramic radiographic data in the subadult group (15-23 year) should only be based on third molar development.

Impacted Mandibular Third Molar, Associated Pathoses, and Their Relation to Angulation and Impaction Depth: A Cone Beam CT Study

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Movahhedian N

2018-03-01

Full Text Available Statement of problem: prophylactic removal of the impacted lower third molar (ILTM is controversial and accompanying pathologic conditions play an important role. Objectives: The aim of the present study is to evaluate the prevalence of commonly found pathoses associated with ILTM in relation to angulation and impaction depth in cone beam computed tomography (CBCT. Materials and Methods: We evaluated CBCT of 500 ILTMs from 235 females (57% and 177 males (43% for the presence of caries on the second and third molars, external root resorption (ERR of the second molar, and follicular spaces (FS >5 mm in diameter in relation to angulation and impaction depth according to Pell and Gregory and Winter’s classifications, respectively. Results: We observed that 55.6% of ILTM had at least one detectible lesion. ERR was the most frequent pathologic condition (31.2%, followed by caries on the second (26% and third (13.4% molars, and FS >5 mm (2.4%. ERR was the only pathology influenced by angulation. There was significantly more ERR in mesioangular ILTMs (40.5%, P5 mm (P=0.035. There were more caries on the second molar (P=0.013 and FS >5 mm (P<0.001 in class III. Conclusions: Prophylactic removal of ILTMs (especially in mesioangular or horizontal impactions could be suggested considering the potential for pathologic changes in ILTMs and the propensity for these teeth to cause ERR in second molars.

Mini-implant-supported Molar Distalization

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Amit Goyal

2012-01-01

Full Text Available Temporary anchorage devices popularly called mini-implants or miniscrews are the latest addition to an orthodontist′s armamentarium. The following case report describes the treatment of a 16-year-old girl with a pleasant profile, moderate crowding and Angle′s Class II molar relationship. Maxillary molar distalization was planned and mini-implants were used to preserve the anterior anchorage. After 13 months of treatment, Class I molar and canine relation was achieved bilaterally and there was no anterior proclination. Thus, mini-implants provide a viable option to the clinician to carry out difficult tooth movements without any side effects.

MOLAR UPRIGHTING

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Eka Erwansyah

2006-04-01

Full Text Available The mesial tipping of molar is frequently found in orthodontic cases. This molar malposition must be corrected since it may cause periodontal disorders, occlusal interferences, and temporomandibular joint dysfunction, and is often needed in planning a fixed bridge. This paper is a literature study to discuss about appliance designs, indication, and contraindications, and complication and treatment protocols of molar uprighting by fixed orthodontic appliances. By knowing the techniques of molar uprighting, the moments mentioned above can be avoided.

Radiographic assessment of agenesis, impaction, and pararadicular radiolucencies in relation with third molar in Nashik City of Maharashtra

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Bhushan Sukdeo Ahire

2016-01-01

Full Text Available Introduction: The third molar develops entirely after birth and also it is the last tooth to erupt in all ethnic groups despite racial variations in the eruption sequence. Tooth development with effects on tooth size, shape, position, and total absence is affected due to environmental factors, systemic diseases, genetic polymorphisms, and teratogens. Aims and Objectives: The aim of this study was to assess the prevalence of agenesis, impaction, and pararadicular radiolucencies in relation with third molars. Materials and Methods: One hundred digital orthopantomograph (OPG scans of patients of age ranging from 18 to 25 years were selected randomly from the digital OPG database of the Department of Oral Medicine and Radiology, and then assessment and analysis were carried out. Results: Overall agenesis rate was about 14.5%. Bilateral agenesis of maxillary and mandibular third molars was about 14% and 13%, respectively. Overall impaction rate was about 21.92%. Mesioangular impaction rate was about 57.33% whereas distoangular impaction rate was about 26.66%. Prevalence of pararadicular radiolucencies was only about 0.8% with mandibular predilection. Conclusion: As the agenesis of the third molars is increasing, they can be considered as vestigial. Prevalence of impaction of the third molars is increasing. Pararadicular radiolucencies are mostly seen with mandibular third molar.

Dental lesions and restorative treatment in molars

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Gheorghiu Irina-Maria

2017-08-01

Full Text Available This article review specific clinical issues of the molar teeth, as well as the therapeutic approach of their pathology. The dental pathology we face in the group of molars is related to: dental caries, dental trauma (crown and crown-root fractures, dental wear phenomena. The therapeutic approach of the molar teeth is represented by: restoration of the loss of hard dental tissues; endodontic treatments of pulpal and periapical complications; surgical treatment. The restorative treatments in molars are: direct restorations, with or without supplementary anchorage for obturations; inlay, onlay; prosthetic crown.

Fusión de un tercer molar mandibular con un cuarto molar supernumerario Fusion of mandibular third molar with supernumerary fourth molar

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C. López Carriches

2008-10-01

Full Text Available La fusión dental es la unión de dos gérmenes dentales normalmente separados, mientras que la geminación se define como el intento de división de un único germen dental. La fusión y geminación de molares es poco frecuente en la dentición permanente. Describimos un caso clínico de un tercer molar inferior derecho fusionado a un cuarto molar supernumerario en un paciente varón de 36 años que ha presentado repetidos episodios de pericoronaritis. Tras el estudio radiológico se realiza la exodoncia del cordal semiincluido bajo anestesia local. Llevamos a cabo una revisión bibliográfica al respecto.Dental fusion is the union of two tooth buds that normally are separated, while gemination is defined as an attempt by a single tooth bud to divide. The fusion and gemination of molars is uncommon in permanent teeth. We report a clinical case of a right lower third molar fused to a supernumerary fourth molar in a 36-year-old male patient with repeated episodes of inflammation. After the radiologic study, the semi-impacted third molar was extracted under local anesthesia. The literature was reviewed.

Influência do agente de cloração do catalisador à base de veodímio e da razão molar Cl: Nd na polimerização do butadieno Influence of the chlorinating agent of neodymium based catalysts and Cl: Nd molar ratio on butadiene polymerization

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Cintia N. Ferreira

2009-06-01

Full Text Available Neste trabalho foi utilizado um sistema catalítico composto por hidreto de diisobutilalumínio (DIBAH, versatato de neodímio (NdV e um agente de cloração para avaliar a influência da fonte de cloro e da razão molar Cl:Nd nas características da reação de polimerização (conversão e constante de velocidade de propagação e do polibutadieno (massa molecular e microestrutura. Os agentes de cloração estudados foram cloreto de t-butila (t-BuCl, sesquicloreto de etilalumínio (EASC e cloreto de dietilalumínio (DEAC. As razões molares Cl:Nd utilizadas foram: 1:1, 3:1 e 5:1 para o t-BuCl; 0,5:1, 1:1 e 3:1 para o EASC e 1:1, 1,5:1, 3:1 e 5:1 para o DEAC. Foi observada a existência, para cada agente de cloração, de um valor ótimo de razão molar Cl:Nd para o qual a conversão foi máxima. O DEAC apresentou uma maior conversão em relação aos outros agentes de cloração; em contrapartida, o t-BuCl produziu polibutadienos com maior teor de unidades 1,4-cis e maior massa molecular (n e wIn this work catalyst systems consisting of diisobutylaluminium hydride (DIBAH, neodymium versatate (NdV and a chlorinating agent were employed to study the influence of the chloride source and Cl:Nd molar ratio on 1,3-butadiene polymerization and polybutadiene's characteristics (molecular weight and microstructure. The chloride sources studied were t-butyl chloride, ethylaluminium sesquichloride (EASC and diethylaluminium chloride (DEAC. The Cl:Nd molar ratios used were 1:1, 3:1 e 5:1 for t-butyl chloride; 0.5:1, 1:1 and 3:1 for EASC and 1:1, 1.5:1, 3:1 and 5:1 for DEAC. A maximum value of Cl:Nd molar ratio exists. Moreover, DEAC showed to be more reactive than EASC and t-BuCl but t-BuCl produced higher molecular weight and cis-1,4 units contents.

Validity of scoring caries and primary molar hypomineralization (DMH) on intraoral photographs.

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Elfrink, M E C; Veerkamp, J S J; Aartman, I H A; Moll, H A; Ten Cate, J M

2009-11-01

The aims of this study were to assess whether intraoral photographs could be used to score caries and hypomineralization on primary molars (Using adapted Molar Incisor Hypomineralization (MIH)-criteria), and also to assess the reliability and validity in 3-7 year-old Dutch children of these scores by comparing them to direct clinical scorings. Cross-sectional study. In this study 62 children (38.7% girls) with a mean age of 4.96 years (SD 1.27) participated. The children were rated clinically by their own dentist (authors JV or ME) for caries reaching the dentine in their primary molars (WHO criteria) and also for primary molar hypomineralization using the adapted MIH-criteria. For the intraoral photographs, a digital intraoral camera was used. The two paediatric dentists rated all the intraoral photographs on caries and hypomineralizations on the second primary molars, using the same criteria for the clinical scoring as for the scoring of the photographs. They scored independently, at least 2 weeks after the initial clinical scoring to avoid observational bias with the clinical scoring. This clinical observation was used as the gold standard from which sensitivity, specificity, Positive Predictive Value (PPV), Negative Predictive Value (NPV) and the Positive and Negative Likelihood Ratio were computed. To test the intra-observer agreement 25 % of the photographs were scored again, at least 2 weeks after the initial scoring of the images. Inter- and intra-observer agreement were tested using Cohen's Kappa. The mean prevalence of clinically detected caries at tooth level was 46.7% and the mean prevalence of clinically detected hypomineralizations in second primary molars at tooth level was 21.8%. The sensitivity of assessing caries using intraoral photographs was 85.5%, the specificity 83.6%, the positive likelihood ratio 5.2 and the negative likelihood ratio was 0.17. For Primary Molar Hypomineralization (DMH) the sensitivity was 72.3%, the specificity 92.8%, the

Adsorption of Nitrite and Nitrate Ions from an Aqueous Solution by Fe-Mg-Type Hydrotalcites at Different Molar Ratios.

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Ogata, Fumihiko; Nagai, Noriaki; Kariya, Yukine; Nagahashi, Eri; Kobayashi, Yuhei; Nakamura, Takehiro; Kawasaki, Naohito

2018-01-01

In this study, we prepared Fe-Mg-type hydrotalcites (Fe-HT3.0 and Fe-HT5.0) with different molar ratios and evaluated their adsorption capability for nitrite and nitrate ions from aqueous solution. Fe-HT is a typical hydrotalcite-like layered double hydroxide. Adsorption isotherms, as well as the effects of contact time and pH were investigated, and it was found that Fe-HT can adsorb larger amounts of nitrite and nitrate ions than Al-HT (normal-type hydrotalcite). Adsorption isotherm data were fitted to both Freundlich (correlation coefficient: 0.970-1.000) and Langmuir (correlation coefficient: 0.974-0.999) equations. Elemental analysis and binding energy of Fe-HT surface before and after adsorption indicated that the adsorption mechanism was related to the interaction between the adsorbent surface and anions. In addition, the ion exchange process is related to the adsorption mechanism. The adsorption amount increased with increasing temperature (7-25°C). The experimental data fit the pseudo-second-order model better than the pseudo-first-order model. The effect of pH on adsorption was not significant, which suggested that Fe-HT could be used over a wide pH range (4-12). These results indicate that Fe-HT is a good adsorbent for the removal of nitrite and nitrate ions from aqueous solution.

AXIAL MODIFICATIONS OF PERMANENT LOWER MOLARS AFTER PREMATURE LOSSES OF TEMPORARY MOLARS.

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Cernei, E R; Mavru, R B; Zetu, Irina Nicoleta

2016-01-01

The aim of our study was to determine the impact of premature loss of temporary lower molars upon the longitudinal axis of the first and second permanent molars. The study groups included 61 patients, 6-9 year olds with premature loss of primary molars and a control group of 24 patients with intact temporary teeth. We evaluated the angle between longitudinal axis of first and second lower permanent molars and occlusal plane. It was observed that premature loss of lower second deciduous molar modifies more the vertical axis of first and second permanent molars than the premature loss of first lower primary molar. Reducing space occurs mainly through mesial inclination of molars that separates the edentulous breach. Temporary loss of both lower first molars on the same quadrant causes an accelerated eruption of both premolars increasing the prevalence of eruption sequence: "4-5-3-7". The preservation of the occlusal morpho-functional complex using space maintainers mainly when the premature loss of the second primary molars occurs is the best interceptive treatment option.

Localization of root canal orifices in mandibular second molars in relation to occlusal dimension.

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Gorduysus, O; Nagas, E; Cehreli, Z C; Gorduysus, M; Yilmaz, Z

2009-11-01

To evaluate the localization and distribution of canal orifices of mandibular second molar teeth in relation to the mesio-distal and bucco-lingual dimensions of coronal tissue. Fifty extracted mandibular second molar teeth were embedded into plaster blocks with their vertical axes aligned perpendicular to the horizontal plane. The teeth were photographed digitally from the occlusal aspect under 12 x magnification. Thereafter, the occlusal halves of crowns were sectioned off to expose the root canal orifices. The teeth were than photographed under the same magnification, after which the pre- and post-sectioning images of each specimen were stacked into a single file. To plot the coordinate of each canal orifice, a 0.5-mm grid analytical plane was mounted digitally on the stack so that the x- and y-axes of the plane were superimposed on the mesiodistal and buccolingual axes (bisectors) of the tooth crowns. Localization and distribution of the coordinates of the canal orifices were evaluated using the chi-square test (P = 0.05). Only one tooth displayed a single root canal orifice, located in the mesiobuccal-distolingual 'centre' of the occlusal surface. The majority of mandibular second molars had three orifices (72%), followed by those with two (16%) and four (10%). The distal canal was located lingual to the centre of the occlusal plane. The distal canal was located lingual to the centre of the occlusal plane of mandibular second molars. The possibility of observing more divergent localizations and orifice numbers should not be overlooked in clinical practice.

First molar cross-bite is more closely associated with a reverse chewing cycle than anterior or pre-molar cross-bite during mastication.

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Tomonari, H; Ikemori, T; Kubota, T; Uehara, S; Miyawaki, S

2014-12-01

A posterior cross-bite is defined as an abnormal bucco-lingual relationship between opposing molars, pre-molars or both in centric occlusion. Although it has been reported that patients with unilateral posterior cross-bite often show unique chewing patterns, the relationship between the form of cross-bite and masticatory jaw movement remains unclear in adult patients. The objective of this study was to investigate masticatory jaw movement among different forms of cross-bite. One hundred and one adults were recruited in this study: 27 had unilateral first molar cross-bite (MC group); 28, unilateral pre-molar cross-bite (PC group); 23, anterior cross-bite (AC group); and 23, normal occlusion (control group). Masticatory jaw movement of the lower incisor point was recorded with six degrees of freedom jaw-tracking system during unilateral mastication. Our results showed that the reverse chewing ratio during deliberate unilateral mastication was significantly larger in the MC group than in the PA (P chewing cycle. © 2014 John Wiley & Sons Ltd.

The influence of premature loss of temporary upper molars on permanent molars.

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Cernei, E R; Maxim, Dana Cristiana; Zetu, Irina Nicoleta

2015-01-01

Premature loss of primary molars due to dental caries and their complications has been associated with space loss and eruptive difficulties, especially when the loss occurs early. The aim of our study was to determine the impact of premature loss of temporary upper molars upon the longitudinal axis of the first and second upper permanent molar. The study group included 64 patients 6-9 years old with premature loss of primary molars and a control group of 48 patients with intact temporary teeth. It was evaluated the angle between longitudinal axis of first and second upper permanent molars and occlusal plane. The sofware used is Easy Dent 4 Viewer®.The data were analyzed by using the Statistical Package for the Social Sciences (version 20.0; SPSS, Chicago, III). It was observed that premature loss of upper second deciduous molars modifies greater the vertical axis of the permanent molars than the premature loss of first upper primary molar. First upper primary molar loss cause an acceleration eruption of first premolar, which will produce a distal inclintion of the both permanent molars. The use of space maintainers after premature loss of the second upper temporary molar is a last solution in preventing tridimensional lesions in the dental arch and occlusion.

Endodontic treatment of a mandibular second molar with four roots – A case report and literature review

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Jorge N.R. Martins

2014-06-01

Conclusions: A configuration with four roots is rare for the mandibular molars. This configuration has an incidence of 0.04% in the first lower molar with only three in vivo case reports available. For the second lower molar, no incidence ratio was found.

Expressly fabricated molar tube bases: enhanced adhesion.

Science.gov (United States)

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

2014-06-01

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

Effect of the Molar Ratio of B2O3 to Bi2O3 in Al Paste with Bi2O3-B2O3-ZnO Glass on Screen Printed Contact Formation and Si Solar Cell Performance

Science.gov (United States)

Kim, Bit-Na; Kim, Hyeong Jun; Chang, Hyo Sik; Hong, Hyun Seon; Ryu, Sung-Soo; Lee, Heon

2013-10-01

In this study, eco-friendly Pb-free Bi2O3-B2O3-ZnO glass frits were chosen as an inorganic additive for the Al paste used in Si solar cells. The effects of the molar ratio of Bi2O3 to B2O3 in the glass composition on the electrical resistance of the Al electrode and on the cell performance were investigated. The results showed that as the molar ratio of Bi2O3 to B2O3 increased, the glass transition temperature and softening temperature decreased because of the reduced glass viscosity. In Al screen-printed Si solar cells, as the molar ratio of Bi2O3 to B2O3 increased, the sheet electrical resistance of the Al electrode decreased and the cell efficiency increased. The uniformity and thickness of the back-surface field was significantly influenced by the glass composition.

Morphometric evaluation of external root resorption of mandibular second molar teeth adjacent to the impacted third molars in CBCT imaging of Tehran\\'s population between 2011-2014

Directory of Open Access Journals (Sweden)

Fatemeh Ezoddini Ardakani

2017-04-01

Full Text Available Introduction: Presence of external root resorption in second molars associated with impacted mandibular third molars was not rare. The neglect of this issue may leads to penetration of the pulp and loss of the second molars. The aim of this study was to investigate the incidence and risk factors affecting the external root resorption in second molars associated with mandibular impacted third molars were inclined mesially and horizontally by Cone Beam Computer Tomography (CBCT images. Methods: In this cross sectional study the samples consisted of 231 scans with mesially and horizontally impacted mandibular third molars. Incidence of external root resorption of second molars and the effects of age, gender and clinical parameters such as location and intensity of external root resorption were considered. Moreover, depth and inclination of impacted mandibular third molar were evaluated by CBCT. The data were analyzed by Chi-square test. Results: The overall incidence of external root resorption in the second molars was 22.08%. Incidence of external root resorption in second molars was significantly related to gender and inclination of third molar. The relations between external root resorption and impaction depth of third molar or the patient's age was not statistically significant. However, the relationship between external root resorption and the intensity or depth of impacted third molar and location of root resorption was statistically meaningful. Conclusion: Patient’s gender and horizontal inclination of third molars are the most important factors affecting the presence of external root resorption in the second molars associated with mesially and horizontally impacted mandibular third molars.

Treatment of ectopic first permanent molar teeth.

Science.gov (United States)

Hennessy, Joe; Al-Awadhi, E A; Dwyer, Lian O; Leith, Rona

2012-11-01

Ectopic eruption of the first permanent molar is a relatively common occurence in the developing dentition. A range of treatment options are available to the clinician provided that diagnosis is made early. Non-treatment can result in premature exfoliation of the second primary molar, space loss and impaction of the second premolar. This paper will describe the management of ectopic first permanent molars, using clinical examples to illustrate the available treatment options. This paper is relevant to every general dental practitioner who treats patients in mixed dentition.

Treatment of ectopic first permanent molar teeth.

LENUS (Irish Health Repository)

Hennessy, Joe

2012-11-01

Ectopic eruption of the first permanent molar is a relatively common occurence in the developing dentition. A range of treatment options are available to the clinician provided that diagnosis is made early. Non-treatment can result in premature exfoliation of the second primary molar, space loss and impaction of the second premolar. This paper will describe the management of ectopic first permanent molars, using clinical examples to illustrate the available treatment options. CLINICAL RELEVANCE: This paper is relevant to every general dental practitioner who treats patients in mixed dentition.

Endodontic management of a mandibular third molar fused with a fourth molar.

Science.gov (United States)

Turell, I L; Zmener, O

1999-05-01

Developmental anomalies in permanent molars frequently require surgical intervention. A case of a mandibular third molar fused with a fourth molar which was successfully treated with conservative endodontic therapy is reported.

Synthesis of geopolymer from spent FCC: Effect of SiO2/Al2O<3 and Na2O/SiO2 molar ratios

Directory of Open Access Journals (Sweden)

Trochez, J. J.

2015-03-01

Full Text Available This paper assesses the feasibility of using a spent fluid catalytic cracking catalyst (SFCC as precursor for the production of geopolymers. The mechanical and structural characterization of alkali-activated SFCC binders formulated with different overall (activator + solid precursor SiO2/Al2O3 and Na2O/SiO2 molar ratios are reported. Formation of an aluminosilicate ‘geopolymer’ gel is observed under all conditions of activation used, along with formation of zeolites. Increased SiO2/Al2O3 induces the formation of geopolymers with reduced mechanical strength, for all the Na2O/SiO2 ratios assessed, which is associated with excess silicate species supplied by the activator. This is least significant at increased alkalinity conditions (higher Na2O/SiO2 ratios, as larger extents of reaction of the spent catalyst are achieved. SiO2/Al2O3 and Na2O/SiO2 ratios of 2.4 and 0.25, respectively, promote the highest compressive strength (67 MPa. This study elucidates the great potential of using SFCC as precursor to produce sustainable ceramic-like materials via alkali-activation.Este artículo estudia la factibilidad de usar un catalizador gastado del proceso de craqueo (SFCC para la producción de geopolímeros. Se evalúan las características mecánicas y estructurales de los geopolímeros producidos con diferentes relaciones molares (activador + precursor solido de SiO2/Al2O3 y Na2O/SiO2. La formación de un gel geopolimérico de tipo aluminosilicato se observa a las diferentes condiciones evaluadas, así como la formación de zeolitas. Un incremento en la relación SiO2/Al2O3 genera geopolímeros de baja resistencia mecánica, a las diferentes relaciones molares Na2O/SiO2 evaluadas, como consecuencia del exceso de especies silicato provenientes del activador. Este efecto es menos significativo al incrementar las condiciones de alcalinidad (mayores relaciones Na2O/SiO2, ya que un mayor grado de reacción del catalizador gastado es alcanzado. Las

CT analyses of the location of the maxillary third molar in relation to panoramic radiographic appearance

International Nuclear Information System (INIS)

Obayashi, Naofumi; Ariji, Yoshiko; Goto, Masakazu; Izumi, Masahiro; Naitoh, Munetaka; Kurita, Kenichi; Shimozato, Kazuo; Ariji, Eiichiro

2009-01-01

We compared the relationship between anatomical structures analyzed by panoramic radiographs and CT images of uninfected impacted maxillary third molars and investigated the pathway of infection originating from pericoronitis of maxillary third molars. Patients (n=62) with uninfected impacted maxillary third molars and patients (n=8) with odontogenic infection originating from pericoronitis of the maxillary third molars were selected from an image database. CT and panoramic images were evaluated separately by an oral surgeon and a radiologist for the vertical position of the tooth, the presence of bone around the crown, proximity to the maxillary sinus, visibility of masticatory muscles, and mesiodistal and buccopalatal inclinations. In uninfected patients, a significant correlation was observed between the vertical positions evaluated by the two methods. Of the third molars, 79 (63.7%) were identified as vertical type on both panoramic and CT images. Regarding the maxillary sinus, of the 19 molars classified as the separate type on panoramic images, 2 (10.5%) were identified as the close type on CT. CT examination revealed the involvement of buccal cortical plates and the buccal space in the majority of infected patients. CT images revealed that 94 molars (75.8%) showed vertical type on the buccopalatal inclination and that 45 impacted molars (36.3%) showed bone defects in the buccal area. Infections originating from pericoronitis of the maxillary third molar showed involvement of the buccal cortical plates, the buccal space, and other spaces, which were clearly depicted on CT images. (author)

The Effect of Si and Al Concentration Ratios on the Removal of U(VI) under Hanford Site 200 Area Conditions-12115

Energy Technology Data Exchange (ETDEWEB)

Katsenovich, Yelena; Gonzalez, Nathan; Moreno-Pastor, Carol; Lagos, Leonel [Applied Research Center, Florida International University, 10555 W. Flagler Street, Miami, FL 33174 (United States)

2012-07-01

Injection of reactive gases, such as NH{sub 3}, is an innovative technique to mitigate uranium contamination in soil for a vadose zone (VZ) contaminated with radionuclides. A series of experiments were conducted to examine the effect of the concentration ratio of silicon to aluminum in the presence of various bicarbonate concentrations on the coprecipitation process of U(VI). The concentration of Al in all tests remained unchanged at 2.8 mM. Experiments showed that the removal efficiency of uranium was not significantly affected by the different bicarbonate and U(VI) concentrations tested. For the lower Si:Al molar ratios of 2:1 and 18:1, the removal efficiency of uranium was relatively low (≤ 8%). For the Si:Al molar ratio of 35:1, the removal efficiency of uranium was increased to an average of ∼82% for all bicarbonate concentrations tested. At higher Si:Al molar ratios (53:1 and above), a relatively high removal efficiency of U(VI), approximately 85% and higher, was observed. These results demonstrate that the U(VI) removal efficiency is more affected by the Si:Al molar ratio than by the bicarbonate concentration in solution. The results of this experiment are promising for the potential implementation of NH{sub 3} gas injection for the remediation of U(VI) -contaminated VZ. (authors)

Radiographic assessment of third molars development and it's relation to dental and chronological age in an Iranian population.

Science.gov (United States)

Monirifard, Mohamad; Yaraghi, Navid; Vali, Ava; Vali, Asana; Vali, Amrita

2015-01-01

The aim of the present study was to estimate chronological age based on third molar development and to determine the association between dental age and third molar calcification stages. In this cross-sectional study, 505 digital panoramic radiographs of 223 males (44.2%) and 282 females (55.8%) between the age of 6 and 17 were selected from patients who were treated in Departments of Pediatrics and Orthodontics of Isfahan University of Medical Sciences between the years of 2009 and 2013. Correlation between chronological age and third molar development was analyzed with SPSS 21 using Spearman's Rank correlation coefficient, Chi-square test and multiple regression statistical tests (P third molars demonstrated a highly significant correlation with dental age (P age were mandibular left third molar in males and mandibular right third molar in females (r s = 0.072). When multiple regression was used to predict dental age based on molar calcification stage, the only significant correlation was between maxillary left third molar in males (P third molars in females. Relationship between chronological age and molars development stage was significant in all age subgroups and in both gender (P third molars and dental age in males. Results showed that third molar calcification stage can be used as an age predictor and in general mandibular teeth seems to be more reliable for this purpose in both genders and in all ages.

Non‑third molar related pericoronitis in a sub‑urban Nigeria ...

African Journals Online (AJOL)

2013-02-28

Feb 28, 2013 ... Chronic pericoronitis was the most common presentation (73.3%). No case was reported in the primary dentition and the premolar. No case was ..... Impacted lower third molars and periodontal health. An epidemiological ...

Aspartic acid racemization in dentin of the third molar for age estimation of the Chaoshan population in South China.

Science.gov (United States)

Chen, Shisheng; Lv, Yanyi; Wang, Dian; Yu, Xiaojun

2016-09-01

Aspartic acid racemization in teeth has been increasingly used to estimate chronological age with a considerably high accuracy in forensic practice. The Chaoshan population in South China is relatively isolated in geography, and has specific lifestyle and dietary inhibits. It is still unknown whether this method is suitable for this population. The aim of this study was to analyze the relationship between chronological age and the d/l aspartic acid ratio in dentin in the third molar tooth of the Chaoshan population. Fifty-eight non-carious third molar teeth (31 mandibles and 27 maxillae), from 58 living individuals of known age (24 males and 34 females), were retrieved. Dentin was extracted from these teeth. The d- and l-aspartic acids in dentins were separated and detected by high performance liquid chromatography (HPLC). Linear regression was performed between the d/l aspartic acid ratio of dentins and chronological age. Results showed that the correlation coefficient (r) was 0.969, and the mean absolute error (MAE) was 2.19 years, its standard deviation (SD) was ±1.53 years, indicating excellent correlation. There was no significant difference in racemization rates of dentin between sexes (P=0.113, F=2.6), or between mandibles and maxillae (P=0.964, F=0.000). Results indicate that the ratio of the d and l forms of aspartic acid of dentins, in the third molar, is closely correlated with chronological age, special lifestyle do no obviously affect the accuracy of the age estimations by aspartic acid racemization of the dentin in the third molar and that aspartic acid racemization in the third molar dentin can be used as an accurate method to estimate chronological age in the Chaoshan population in South China. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Fusion of mandibular third molar with supernumerary fourth molar

OpenAIRE

López Carriches, C.; Leco Berrocal, I.; Baca Pérez-Bryan, R.

2008-01-01

La fusión dental es la unión de dos gérmenes dentales normalmente separados, mientras que la geminación se define como el intento de división de un único germen dental. La fusión y geminación de molares es poco frecuente en la dentición permanente. Describimos un caso clínico de un tercer molar inferior derecho fusionado a un cuarto molar supernumerario en un paciente varón de 36 años que ha presentado repetidos episodios de pericoronaritis. Tras el estudio radiológico se realiza la exodoncia...

A hidden variable in shear transformation zone volume versus Poisson's ratio relation in metallic glasses

Science.gov (United States)

Kim, S. Y.; Oh, H. S.; Park, E. S.

2017-10-01

Herein, we elucidate a hidden variable in a shear transformation zone (STZ) volume (Ω) versus Poisson's ratio (ν) relation and clarify the correlation between STZ characteristics and the plasticity of metallic glasses (MGs). On the basis of cooperative shear model and atomic stress theories, we carefully formulate Ω as a function of molar volume (Vm) and ν. The twofold trend in Ω and ν is attributed to a relatively large variation of Vm as compared to that of ν as well as an inverse relation between Vm and ν. Indeed, the derived equation reveals that the number of atoms in an STZ instead of Ω is a microstructural characteristic which has a close relationship with plasticity since it reflects the preference of atomistic behaviors between cooperative shearing and the generation of volume strain fluctuation under stress. The results would deepen our understanding of the correlation between microscopic behaviors (STZ activation) and macroscopic properties (plasticity) in MGs and enable a quantitative approach in associating various STZ-related macroscopic behaviors with intrinsic properties of MGs.

Image and surgery-related costs comparing cone beam CT and panoramic imaging before removal of impacted mandibular third molars

DEFF Research Database (Denmark)

Petersen, Lars Bo; Olsen, Kim Rose; Christensen, Jennifer Heather

2014-01-01

resource utilization. Differences in resources used for surgical and post-surgical management were calculated for each patient. Results: Converted to monetary units, the total costs for panoramic imaging equalized (sic)49.29 and for CBCT examination (sic)184.44. Modifying effects on this outcome......Objectives: The aim of this prospective clinical study was to derive the absolute and relative costs of cone beam CT (CBCT) and panoramic imaging before removal of an impacted mandibular third molar. Furthermore, the study aimed to analyse the influence of different cost-setting scenarios...... on the outcome of the absolute and relative costs and the incremental costs related to surgery. Methods: A randomized clinical trial compared complications following surgical removal of a mandibular third molar, where the pre-operative diagnostic method had been panoramic imaging or CBCT. The resources implied...

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

International Nuclear Information System (INIS)

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

1983-01-01

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

[Correlation between the lower first permanent molar axis and the premature loss of temporary molars].

Science.gov (United States)

Petcu, Ana; Maxim, A; Haba, Danisia

2009-01-01

The aim of our study was to determine the impact of premature loss of temporary molars upon the longitudinal axis of the first permanent molar. The study sample was formed by 94 orthopanthomografies of child patients with premature loss of lower temporary molars (first or second) after clinical eruption of the first permanent molar. All panoramic radiographs have been realized with the same panoramic unit with 1.4% magnification coefficient and were analyzed using a standardized technique of tracing the images of teeth and bone on matte acetate paper. It was evaluated the angle between longitudinal axis of first permanent lower molar and occlusal plane. It was observed that premature loss of lower second deciduous molar modifies greater the vertical axis of first permanent molar (between 61 degrees and 79 degrees) then premature loss of first lower primary molar. This is perhaps because the loss of space in the case of premature exfoliation of first primary molar is due more to distal drift of canine then mesial drift of molars. The drift to mesial of first permanent molar is more accentuated proportional with the age at which appeared premature loss and so it is loss of leeway space.

Vasoconstrictor effect of high FFA/albumin ratios in adipose tissue in vivo

DEFF Research Database (Denmark)

Bülow, J; Madsen, J; Astrup, A

1985-01-01

Subcutaneous or perirenal adipose tissue blood flow was measured with the 133Xe-washout technique before and after intravenous injection or infusion of Intralipid in six anesthetized, otherwise intact mongrel dogs. In four anesthetized mongrel puppies adipose tissue blood flow was measured...... as well as in young dogs after this treatment. The administration of Intralipid did not per se induce the vasoconstriction. The vasoconstriction took place simultaneously with increasing FFA/albumin molar ratios. The results support our previous findings in perfused fat pads that high molar FFA....../albumin ratios increase vascular resistance in adipose tissue and they give further support to our suggestion that this vasoconstriction may be a link in a negative-feedback mechanism regulating FFA-mobilization in relation to FFA utilization....

[Hyperthyroidism in molar pregnancy].

Science.gov (United States)

Boufettal, H; Mahdoui, S; Noun, M; Hermas, S; Samouh, N

2014-03-01

Hyperthyroidism is a rare complication of molar pregnancy. We report a 39-year-old woman who presented a thyrotoxic syndrome accompanying a molar pregnancy. Serum thyroid hormones were elevated and returned to normal level after uterine evacuation of a molar pregnancy. The authors detail the role of thyroid stimulating property of human gonadotropin chorionic hormone and its structural changes during the gestational trophoblastic diseases. These changes give the latter the thyroid stimulating properties and signs of hyperthyroidism. Molar pregnancy may be a cause of hyperthyroidism. The diagnosis of molar pregnancy should be a mention to thyrotoxicosique syndrome in a woman of childbearing age. Copyright © 2013. Published by Elsevier SAS.

SECOND MOLAR UPRIGHTING AFTER PREMATURE LOSS OF MANDIBULAR FIRST PERMANENT MOLAR--CASE REPORT.

Science.gov (United States)

Cernei, E R; Mavru, R B; Zetui, Irina Nicoleta

2015-01-01

Uprighting a tipped molar by using an uprighting spring is a fundamental orthodontic treatment technique. Following a weak anchorage done only by the anterior teeth the permanent lower second molar will rotate around its center of resistance, and besides the distalizing movement will occur its extrusion. Following the reaction, the mandibular anterior teeth will have a movement of intrusion. All these elements will lead to anterior open bite. Correction of vertical problems has become easier with the advent of mini-implants. U.I patient aged 24 years presenting for aesthetic and functional disorders. Clinical examination reveals intraoral Class I molar malocclusion on the right sight, upper narrowing arch with a slight overbite, and the both permanent first molars on the left side lost prematurely. The tooth 37 is inclined at 600 degrees to the plane of occlusion. To avoid front opening occlusion we used an orthodontic miniscrew inserted between the canine and the first premolar on the same side to achieve the second molar up righting. Lower second molar uprighting was achieved without unwanted movements in anterior mandibular region and without molar extrusion. Using mini implants in uprighting a tipped molar will achieve the desired tooth movement and will reduce the number of unwanted side effects and eventually to improve patient's esthetics.

Finishing occlusion in Class II or Class III molar relation: therapeutic Class II and III.

Science.gov (United States)

Nangia, A; Darendeliler, M A

2001-11-01

The most frequent extraction regime consists of the removal of upper and lower premolars. Depending on anchorage requirements, camouflage treatment options, surgical intervention, or the absence of teeth in only one arch, it may become necessary to finalize the occlusion with a one-dental-unit discrepancy between the upper and lower dental arches. Guidelines are presented for finishing occlusions in Class II or Class III molar relation.

Drugs related to the etiology of molar incisor hypomineralization: A systematic review.

Science.gov (United States)

Serna, Clara; Vicente, Ascensión; Finke, Christian; Ortiz, Antonio J

2016-02-01

Molar incisor hypomineralization (MIH) is an idiopathic syndrome that has been associated with several etiologic factors. The authors' objective was to systematically review studies in which the investigators had studied how the etiology of MIH was related to medication intake. The search covered a period from January 1, 1965, to September 29, 2014. The search revealed 1,042 articles, to which the authors applied eligibility criteria and selected 20 studies for review. The authors considered 9 of the 20 studies to be high quality. The drugs used in these studies were chemotherapeutic drugs, antibiotics, asthma drugs, antiepileptic drugs, antiviral drugs, antifungal drugs, and antiparasitic drugs. Two reviewers independently performed risk-of-bias assessment and data extraction. The investigators of all of the studies had reported enamel defects, but only 2 sets of investigators had used the term "molar incisor hypomineralization." Owing to the different methodologies used by the investigators of the selected studies, the authors could not perform a meta-analysis of the study results. More well-designed prospective studies are needed to clarify the relationship between MIH and medication. It would be convenient to establish a preventive protocol in patients with a potential risk of developing MIH to avoid the complications that are characteristic of this disease. Copyright © 2016 American Dental Association. Published by Elsevier Inc. All rights reserved.

Removable molar power arm

Directory of Open Access Journals (Sweden)

Raj Kumar Verma

2013-01-01

Full Text Available Attachment of force elements from the gingival hook of maxillary molar tubes during the retraction of the anterior teeth is very common in orthodontic practice. As the line of force passes below the center of resistance (CR of molar, it results its mesial tipping and also anchorage loss. To overcome this problem, the line of force should pass along the CR of molar. This article highlights a method to overcome this problem by attaching a removable power arm to the headgear tube of molar tube during the retraction of the anterior teeth.

Effect of Alkaline Activator to Fly Ash Ratio for Geopolymer Stabilized Soil

Directory of Open Access Journals (Sweden)

Abdullah Muhammad Sofian

2017-01-01

Full Text Available Geopolymer technology have been developed and explored especially in the construction material field. However, lack of research related to geopolymer stabilized soil. In this research, the utilization of geopolymer has been investigated to stabilize the soil including the factors that affecting the geopolymerization process. Unconfined compressive test (UCT used as indicator to the strength development and hence evaluating the performance of geopolymer stabilized soil. This paper focusing on the effect of fly ash/alkaline activator ratio, Na2SiO3/NaOH ratio and curing time on geopolymer stabilized soil. A various mix design at different fly ash/alkaline activator ratio, Na2SiO3/NaOH ratio were prepared and cured for 7 and 28 days. Molarity and the percentage of geopolymer to soil were fixed at 10 molar and 8 percent respectively. Then, the UCT tests were carried out on 38mm diameter x 76mm height specimens. The highest strength obtained at the fly ash/alkaline activator ratio 2.5 and Na2SiO3/NaOH ratio 2.0 at 28 days curing time.

Three-dimensional primate molar enamel thickness.

Science.gov (United States)

Olejniczak, Anthony J; Tafforeau, Paul; Feeney, Robin N M; Martin, Lawrence B

2008-02-01

Molar enamel thickness has played an important role in the taxonomic, phylogenetic, and dietary assessments of fossil primate teeth for nearly 90 years. Despite the frequency with which enamel thickness is discussed in paleoanthropological discourse, methods used to attain information about enamel thickness are destructive and record information from only a single plane of section. Such semidestructive planar methods limit sample sizes and ignore dimensional data that may be culled from the entire length of a tooth. In light of recently developed techniques to investigate enamel thickness in 3D and the frequent use of enamel thickness in dietary and phylogenetic interpretations of living and fossil primates, the study presented here aims to produce and make available to other researchers a database of 3D enamel thickness measurements of primate molars (n=182 molars). The 3D enamel thickness measurements reported here generally agree with 2D studies. Hominoids show a broad range of relative enamel thicknesses, and cercopithecoids have relatively thicker enamel than ceboids, which in turn have relatively thicker enamel than strepsirrhine primates, on average. Past studies performed using 2D sections appear to have accurately diagnosed the 3D relative enamel thickness condition in great apes and humans: Gorilla has the relatively thinnest enamel, Pan has relatively thinner enamel than Pongo, and Homo has the relatively thickest enamel. Although the data set presented here has some taxonomic gaps, it may serve as a useful reference for researchers investigating enamel thickness in fossil taxa and studies of primate gnathic biology.

Efficacy and safety of combined piroxicam, dexamethasone, orphenadrine, and cyanocobalamin treatment in mandibular molar surgery

Directory of Open Access Journals (Sweden)

Barroso A.B.

2006-01-01

Full Text Available Third molar extraction is a common procedure frequently accompanied by moderate or severe pain, and involves sufficient numbers of patients to make studies relatively easy to perform. The aim of the present study was to determine the efficacy and safety of the therapeutic combination of 10 mg piroxicam, 1 mg dexamethasone, 35 mg orphenadrine citrate, and 2.5 mg cyanocobalamin (Rheumazin® when compared with 20 mg piroxicam alone (Feldene® in mandibular third molar surgery. Eighty patients scheduled for removal of the third molar were included in this randomized and double-blind study. They received (vo Rheumazin or Feldene 30 min after tooth extraction and once daily for 4 consecutive days. Pain was determined by a visual analogue scale and by the need for escape analgesia (paracetamol. Facial swelling was evaluated with a measuring tape and adverse effects and patient satisfaction were recorded. There was no statistically significant difference in facial swelling between Rheumazin and Feldene (control group. Both drugs were equally effective in the control of pain, with Rheumazin displaying less adverse effects than Feldene. Therefore, Rheumazin appears to provide a better risk/benefit ratio in the mandibular molar surgery. Since the side effects resulting from nonsteroidal anti-inflammatory drug administration are a severe limitation to the routine use of these drugs in clinical practice, our results suggest that Rheumazin can be a good choice for third molar removal treatment.

Efficacy and safety of combined piroxicam, dexamethasone, orphenadrine, and cyanocobalamin treatment in mandibular molar surgery

Directory of Open Access Journals (Sweden)

A.B. Barroso

Full Text Available Third molar extraction is a common procedure frequently accompanied by moderate or severe pain, and involves sufficient numbers of patients to make studies relatively easy to perform. The aim of the present study was to determine the efficacy and safety of the therapeutic combination of 10 mg piroxicam, 1 mg dexamethasone, 35 mg orphenadrine citrate, and 2.5 mg cyanocobalamin (Rheumazin® when compared with 20 mg piroxicam alone (Feldene® in mandibular third molar surgery. Eighty patients scheduled for removal of the third molar were included in this randomized and double-blind study. They received (vo Rheumazin or Feldene 30 min after tooth extraction and once daily for 4 consecutive days. Pain was determined by a visual analogue scale and by the need for escape analgesia (paracetamol. Facial swelling was evaluated with a measuring tape and adverse effects and patient satisfaction were recorded. There was no statistically significant difference in facial swelling between Rheumazin and Feldene (control group. Both drugs were equally effective in the control of pain, with Rheumazin displaying less adverse effects than Feldene. Therefore, Rheumazin appears to provide a better risk/benefit ratio in the mandibular molar surgery. Since the side effects resulting from nonsteroidal anti-inflammatory drug administration are a severe limitation to the routine use of these drugs in clinical practice, our results suggest that Rheumazin can be a good choice for third molar removal treatment.

MicroCT study on the enamel mineral density of primary molars

NARCIS (Netherlands)

Elfrink, M.E.C.; Kalin, K.; van Ruijven, L.J.; ten Cate, J.M.; Veerkamp, J.S.J.

2016-01-01

Aim The aim of this study is to report on the mineral density of the enamel of primary molars related to the age of the child and to compare the mineral density of sound and carious enamel in those molars. Materials and methods This study included 23 children and 41 extracted primary molars. The

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

Science.gov (United States)

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

2015-01-01

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

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

Directory of Open Access Journals (Sweden)

Bernardo Q Souki

2015-01-01

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

Root growth during molar eruption in extant great apes.

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Kelley, Jay; Dean, Christopher; Ross, Sasha

2009-01-01

While there is gradually accumulating knowledge about molar crown formation and the timing of molar eruption in extant great apes, very little is known about root formation during the eruption process. We measured mandibular first and second molar root lengths in extant great ape osteological specimens that died while either the first or second molars were in the process of erupting. For most specimens, teeth were removed so that root lengths could be measured directly. When this was not possible, roots were measured radiographically. We were particularly interested in the variation in the lengths of first molar roots near the point of gingival emergence, so specimens were divided into early, middle and late phases of eruption based on the number of cusps that showed protein staining, with one or two cusps stained equated with immediate post-gingival emergence. For first molars at this stage, Gorilla has the longest roots, followed by Pongo and Pan. Variation in first molar mesial root lengths at this stage in Gorilla and Pan, which comprise the largest samples, is relatively low and represents no more than a few months of growth in both taxa. Knowledge of root length at first molar emergence permits an assessment of the contribution of root growth toward differences between great apes and humans in the age at first molar emergence. Root growth makes up a greater percentage of the time between birth and first molar emergence in humans than it does in any of the great apes. Copyright (c) 2009 S. Karger AG, Basel.

The premature loss of primary first molars: space loss to molar occlusal relationships and facial patterns.

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Alexander, Stanley A; Askari, Marjan; Lewis, Patricia

2015-03-01

To investigate space changes with the premature loss of primary first molars and their relationship to permanent molar occlusion and facial forms. Two hundred twenty-six participants (ranging in age from 7 years 8 months to 8 years 2 months; 135 female, 91 male) met all inclusion criteria designed to study space loss as a result of the premature loss of the primary first molar. After 9 months, space loss was evaluated in relationship to molar occlusion and facial form. Statistical evaluation was performed with the paired t-test and with a two-way analysis of variance for independent groups. Patients with leptoprosopic facial form and end-on molar occlusions all exhibited a statistically significant difference when compared to controls in terms of space loss (P molar occlusion displayed space loss as well (P molar occlusion displayed space loss in the maxilla (P molar occlusions showed no significant difference in space loss. The relationship between the first permanent molar occlusion and facial form of the child has an influence on the loss of space at the primary first molar site.

Circulating levels of IGF-1, IGFBP-3, and IGF-1/IGFBP-3 molar ratio and colorectal adenomas: A meta-analysis.

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Yoon, Yeong Sook; Keum, NaNa; Zhang, Xuehong; Cho, Eunyoung; Giovannucci, Edward L

2015-12-01

Insulin-like growth factor-1(IGF-1) promotes cell proliferation and inhibits apoptosis, and is thereby implicated in carcinogenesis. Insulin-like growth factor binding protein-3 (IGFBP-3) may antagonize IGF-1 action, leading to inhibition of the potential tumorigenicity of IGF-1. We conducted this meta-analysis to estimate the association between IGF-1, IGFBP-3 and IGF-1/IGFBP-3 ratio and the risk of colorectal adenomas (CRAs). Further, we investigated whether this association was different between occurrent and recurrent CRA, by adjustment for obesity, and by advanced CRA. Pubmed and Embase were searched up to April, 2015 to identify relevant observational studies and summary odds ratio (OR) and the corresponding 95% confidence interval (95% CI) was estimated using a random-effects model. A total of 12 studies (11 studies including 3038 cases for IGF-1, 12 studies including 3208 cases for IGFBP-3, and 7 studies including 1867 cases for IGF-1/IGFBP-3 ratio) were included in this meta-analysis. The summary ORs of occurrent CRA for the highest versus lowest category of IGF-1, IGFBP-3 and IGF-1/IGFBP-3 ratio were 1.13 (95% CI: 0.95-1.34), 0.99 (0.84-1.16), and 1.05 (0.86-1.29), respectively. Higher IGF-1 and IGF-1/IGFBP-3 ratio were significantly associated with decreased risk of recurrent CRA (OR for IGF-1=0.60 [95% CI: 0.42-0.85]; IGF-1/IGFBP-3 ratio=0.65 [0.44-0.96]). A stratified analysis by advancement of occurrent CRA produced a significant summary OR of IGF-1 for advanced CRA (OR=2.21 [1.08-4.52]) but not for non-advanced CRA (OR=0.89 [0.55-1.45]). We did not find significant publication bias or heterogeneity. Circulating levels of IGF-1, IGFBP-3 and their molar ratio were not associated with the risk of occurrence of CRA, but IGF-1 was associated with the increased risk for occurrence of advanced CRA. Copyright © 2015. Published by Elsevier Ltd.

Defluoridation of drinking water by combined electrocoagulation: effects of the molar ratio of alkalinity and fluoride to Al(III).

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Zhao, Hua-Zhang; Yang, Wei; Zhu, Jun; Ni, Jin-Ren

2009-03-01

The defluoridation efficiency (epsilon(F)) of electrocoagulation (EC) is closely related to the pH level of the F(-)-containing solution. The pH level usually needs to be adjusted by adding acid in order to obtain the highest epsilon(F) for the F(-)-containing groundwater. The use of combined EC (CEC), which is the combination of chemical coagulation with EC, was proposed to remove fluoride from drinking water for the first time in this study. The optimal scheme for the design and operation of CEC were obtained through experiments on the treatment of F(-)-containing groundwater. It was found, with OH(-) being the only alkalinity of the raw water, that the highest efficiency would be obtained when the molar ratio of alkalinity and fluoride to Al(III) (gamma(Alkalinity+F)) was controlled at 3.0. However, when the raw water contained HCO(3)(-) alkalinity, a correction coefficient was needed to correct the concentration of HCO(3)(-) to obtain the optimal defluoridation condition of gamma(Alkalinity+F)=3.0 for CEC. The correction coefficient of HCO(3)(-) concentration was concluded as 0.60 from the experiment. For the practical F(-)-containing groundwater treatment, CEC can achieve similar epsilon(F) as an acid-adding EC process. The consumption of aluminum electrode was decreased in CEC. The energy consumption also declined greatly in CEC, which is less than one third of that in the acid-adding EC process.

Child oral health-related quality of life (COHQoL), enamel defects of the first permanent molars and caries experience among children in Western Australia.

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Arrow, P

2013-09-01

Published reports suggest that children with enamel defects, especially where enamel is missing or breaking down, experience considerable discomfort and are generally more fearful of dental treatment. However, children's oral health-related quality of life in relation to enamel defects has not been reported. The aim of this study was to examine the association between oral health-related quality of life among children (COHQoL) with enamel defects of the first permanent molars and deciduous caries experience. Children attending pre-primary schools in metropolitan Perth, Western Australia, were recruited and classified for enamel defects using the modified Developmental Defects of Enamel index. Caries experience of deciduous molars and canines was also recorded. Parents completed a child oral health-related quality of life questionnaire. Data were analysed using Kruskal-Wallis, Spearman's rank correlation, chi-square, multiple linear regression and ordered logistic regression to test the factors for their influence on the COHQoL. From the 550 children assessed (mean age 7.2 years) 522 COHQoL questionnaires were returned. Mean COHQoL score was 8.9 (sd 8.8). Bivariate tests showed no association of COHQoL with enamel defect status of the first permanent molars. COHQoL was associated with dmft (mean dmft 1.96, sd 2.62). Higher caries experience children had poorer reported oral health-related quality of life. The presence of enamel defects in the first permanent molars did not affect the children's oral health-related quality of life.

Are Hypomineralized Primary Molars and Canines Associated with Molar-Incisor Hypomineralization?

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da Silva Figueiredo Sé, Maria Jose; Ribeiro, Ana Paula Dias; Dos Santos-Pinto, Lourdes Aparecida Martins; de Cassia Loiola Cordeiro, Rita; Cabral, Renata Nunes; Leal, Soraya Coelho

2017-11-01

The purpose of this study was to evaluate the prevalence of and relationship between hypomineralized second primary molars (HSPM) and hypomineralized primary canines (HPC) with molar-incisor hypomineralization (MIH) in 1,963 schoolchildren. The European Academy of Paediatric Dentistry (EAPD) criterion was used for scoring HSPM/HPC and MIH. Only children with four permanent first molars and eight incisors were considered in calculating MIH prevalence (n equals 858); for HSPM/HPC prevalence, only children with four primary second molars (n equals 1,590) and four primary canines (n equals 1,442) were considered. To evaluate the relationship between MIH/HSPM, only children meeting both criteria cited were considered (n equals 534), as was true of MIH/HPC (n equals 408) and HSPM/HPC (n equals 360; chi-square test and logistic regression). The prevalence of MIH was 14.69 percent (126 of 858 children). For HSPM and HPC, the prevalence was 6.48 percent (103 of 1,592) and 2.22 percent (32 of 1,442), respectively. A significant relationship was observed between MIH and both HSPM/HPC (PMIH based on HSPM was 6.31 (95 percent confidence interval [CI] equals 2.59 to 15.13) and for HPC was 6.02 (95 percent CI equals 1.08 to 33.05). The results led to the conclusion that both hypomineralized second primary molars and hypomineralized primary canines are associated with molar-incisor hypomineralization, because children with HSPM/HPC are six times more likely to develop MIH.

Mini implant supported molar tubes: A novel method for attaching the molar tubes

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Nitin V Muralidhar

2017-01-01

Full Text Available Banding or bonding procedures have been the only means of attaching molar tubes onto the permanent molar teeth till date in the field of orthodontics. This clinical innovation aims to include the use of mini implant for the purpose of attaching the molar tubes thereby eliminating the iatrogenic effects of banding and bonding of the teeth.

Molar exergy and flow exergy of pure chemical fuels

International Nuclear Information System (INIS)

Zanchini, Enzo; Terlizzese, Tiziano

2009-01-01

Expressions of the molar exergy and of the molar flow exergy of a pure chemical fuel are deduced rigorously from the basic principles of thermodynamics. It is shown that molar exergy and molar flow exergy coincide when the temperature T and the pressure p of the fuel are equal to the temperature T B and the pressure p B of the environment; a general relation between exergy and flow exergy is proved as a consequence. The deduction of the expression of the molar exergy of a chemical fuel for non-standard values of T B and p B is clarified. For hydrogen, carbon dioxide and several hydrocarbons, tables are reported to allow a simple calculation of the molar exergy of the fuel for any value of the temperature T B and the relative humidity φ B of the environment, in the range 268.15 K ≤ T B ≤ 313.15 K and 0.1 ≤ φ B ≤ 1, with reference to the standard atmospheric pressure. Additional tables are provided to evaluate the difference between the exergy or the flow exergy of the fuel in its given initial state and the exergy at T = T B and p = p B . In these tables, it is assumed that fuel and environment have the same temperature and that the fuel pressure varies in the range 1.01325 bar ≤ p ≤ 200 bar; the fuel may be gas or liquid.

Analysis of the mineral composition of hypomineralized first permanent molars

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Martinović Brankica

2015-01-01

Full Text Available Background/Aim. Hypomineralization of molars and incisors (molar-incisor hypomineralization - MIH is defined as enamel hypomineralization of systemic origin of one or more of the four first permanent molars, which may be associated with changes in the maxillary, and less frequently in the permanent mandibular incisors. The aim of this study was to investigate the mineral content in hypomineralized teeth as a contribution to under-standing the origin of these changes, which will be important for effective restorative approach. Methods. A total of 10 extracted first permanent molars diagnosed with MIH were used in the study as the experimental group, and intact first premolars extracted for orthodontic reasons were used as the control group. A certain surface of hypomineralized аnd healthy enamel and dentin was analyzed using a scanning electron microscope equipped with an energydispersive spectrometer (SEM/EDS. Results. By conducting quantitative chemical analysis of the distribution of the basic chemical elements, it was found that the concentration of calcium (Ca and phosphorus (P was significantly higher in healthy enamel (Ca = 28.80 wt%, and P = 15.05 wt% compared to hypomineralized enamel (Ca = 27.60 wt% and P = 14.32 wt%. Carbon (C concentration was statistically significantly higher in hypomineralized enamel (C = 11.70 wt% compared to healthy enamel (C = 10.94 wt%. Hypomineralized and healthy enamel did not differ significantly regarding the ratio of calcium and phosphorus concentrations whereas the ratio of calcium and carbon concentrations was statistically significantly higher in healthy enamel compared to hypomineralized enamel. Conclusion. Concentration of the main chemical elements, primarily calcium and phosphorus, is significantly reduced in hypomineralized enamel whereas carbon concentration is increased compared to healthy enamel.

Primary molar pulpotomy: a systematic review and network meta-analysis.

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Lin, Po-Yen; Chen, Hsueh-Szu; Wang, Yu-Hsiang; Tu, Yu-Kang

2014-09-01

Pulpotomy is a common procedure to treat asymptomatic reversible pulpitis in primary molars. The aim of this study is to undertake a systematic review and a network meta-analysis to compare the clinical and radiographic outcomes of different pulpotomy procedures in primary molars. Three authors performed data extraction independently and in duplicate using data collection forms. Disagreements were resolved by discussion. An electronic literature search was performed within MEDLINE (via PubMed), ScienceDirect, Web of Science, Cochrane, and ClinicalKey databases until December 2012. Medications for pulpotomy including formocresol, ferric sulfate, calcium hydroxide, and mineral trioxide aggregate (MTA), and laser pulpotomy are compared using Bayesian network meta-analyses. The outcome is the odds ratio for clinical and radiographic failure including premature tooth loss at 12 and 24 months after treatments amongst different treatment procedures. 37 studies were included in the systematic review, and 22 of them in the final network meta-analyses. After 18-24 months, in terms of treatment failure, the odds ratio for calcium hydroxide vs. formocresol was 1.94 [95% credible interval (CI): 1.11, 3.25]; 3.38 (95% CI: 1.37, 8.61) for lasers vs. formocresol; 2.16 (95% CI: 1.12, 4.31) for calcium hydroxide vs. ferric sulfate; 3.73 (95% CI: 1.27, 11.67) for lasers vs. ferric sulfate; 0.47 (95% CI: 0.26, 0.83) for MTA vs. calcium hydroxide; 3.76 (95% CI: 1.39, 10.08) for lasers vs. After 18-24 months, formocresol, ferric sulfate, and MTA showed significantly better clinical and radiographic outcomes than calcium hydroxide and laser therapies in primary molar pulpotomies. The network meta-analyses showed that MTA is the first choice for primary molar pulpotomies. However, if treatment cost is an issue, especially when the treated primary molars are going to be replaced by permanent teeth, ferric sulfate may be the choice. Copyright © 2014 Elsevier Ltd. All rights reserved.

Observation of positional relation between mandibular third molars and the mandibular canal on limited cone beam computed tomography

International Nuclear Information System (INIS)

Hashizume, Atsuko; Nakagawa, Yoichi; Ishii, Hisako; Kobayashi, Kaoru

2004-01-01

We describe the preoperative use of limited cone beam computed tomography (CT) with a dental CT scanner for the assessment of mandibular third molars before extraction. Cone beam CT provides 42.7-mm-high and 30-mm-wide rectangular solid images, with a resolution of less than 0.2 mm. The positional relationship between the mandibular third molars and the mandibular canal was examined by dental CT. Sixty-eight lower third molars of 62 patients whose teeth were superimposed on the mandibular canal on periapical or panoramic radiographs were studied. Dental CT scans clearly demonstrated the positional relationship between the mandibular canal and the teeth. The mandibular canal was located buccally to the roots of 16 teeth, lingually to the roots of 27 teeth, inferiorly to the roots of 23 teeth, and between the roots of 2 teeth. The presence of bone between the mandibular canal and the teeth was not noted in 7 of 16 buccal cases, 24 of 27 lingual cases, and 10 of 23 inferior cases on dental CT scans, suggesting that the canal was in contact with the teeth. Fifty-nine of the 68 mandibular third molars were surgically removed, and postoperative transient hypoesthesia occurred in 4 patients. Dental CT scans showed no bone between the mandibular canal and the teeth in all 4 patients. Hypoesthesia was not related to the bucco-lingual location of the mandibular canal or to the extent of bone loss between the canal and the teeth. However, hypoesthesia did not occur in patients with bone between the mandibular canal and the teeth. Thus, information on the distance between the canal and teeth on dental CT scans was useful for predicting the risk of inferior alveolar nerve damage. Because of its high resolution and low radiation dose, cone beam CT was useful for examination before mandibular third molar surgery. (author)

Excess molar enthalpies for binary mixtures of different amines with water

International Nuclear Information System (INIS)

Zhang, Ruilei; Chen, Jian; Mi, Jianguo

2015-01-01

Highlights: • Isothermal excess molar enthalpies for binary mixtures of different amines with water. • The Redlich–Kister equation and the NRTL model was used to fit the experimental data. • The excess molar enthalpies were discussed with different structures of amines. - Abstract: The isothermal excess molar enthalpies for binary mixtures of different amines with water were measured with a C-80 Setaram calorimeter. The experimental results indicate that the excess molar enthalpy is related to the molecular structure. The experimental excess molar enthalpies were satisfactorily fitted with the Redlich–Kister equation. They were also used to test the suitability of the NRTL model, and the deviations are a little larger than the R–K equation

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

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Bedenbaugh, John H.; And Others

1988-01-01

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

Extrações de molares na Ortodontia Molar extractions in orthodontics

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Marco Antônio Schroeder

2011-12-01

Full Text Available O tratamento ortodôntico com extração de molares em pacientes adultos é tecnicamente mais complexo, devido a inúmeros fatores. Em geral, o espaço a ser fechado é maior do que o espaço dos pré-molares e, por isso, a ancoragem é crítica e o tempo de tratamento mais longo. É comum esses casos apresentarem algum grau de comprometimento periodontal por causa da idade dos pacientes e, portanto, necessitam de maior controle da mecânica ortodôntica para reduzir os efeitos colaterais do fechamento do espaço. Por isso, bons resultados de finalização são mais difíceis de ser alcançados. Sendo assim, este artigo tem como objetivo apresentar as razões para a indicação de extração de molares nos tratamentos ortodônticos, as contraindicações, as diferentes fases da mecânica ortodôntica, esclarecer os fatores envolvidos nesse tipo de planejamento e tratamento e apresentar casos clínicos tratados com extração de molares.Orthodontic treatment with extraction of molars in adult patients is technically more complex due to a number of factors. In general, the space to be closed is greater than premolar spaces rendering critical anchorage and longer treatment time. Often such cases exhibit some degree of periodontal involvement due to patient age. Hence, the need for greater control over orthodontic mechanics to reduce the side effects of space closure. Therefore, good finishing results can be more difficult to achieve. Thus, the purpose of this article is to determine the reasons for molar extraction indications, describe different stages of orthodontic mechanics, and explain the issues involved in this kind of planning and treatment. Additionally, it aims at describing some treatments with molar extractions.

Elective extractions of first permanent molars: a review

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Melike Kiraz

2018-05-01

Full Text Available Permanent first molar teeth possess a key role in the setting-up of the occlusion, contribute significantly to the chewing function and serve as a guide for other teeth. However, it is frequently encountered that permanent first molar teeth are extracted due to the predicted negative prognoses of caries or developmental defects. As a result of the uncontrolled extraction of the permanent first molar teeth during the growth and development period, drifting of adjacent teeth, continued eruption of the opposing teeth and displacements can be seen. Furthermore, following one-sided extraction, midline deviations, oppositional tooth eruption, skeletal and dental asymmetry, unilateral chewing habits, and temporo-mandibular joint disorders may occur. To prevent these pathological conditions and to maintain the stability of the occlusal relation, it is necessary to do compensation and balancing extractions of the permanent first molar teeth on the opposite/symmetric arc, assuming mesial drag of the permanent second and third molar teeth. With such controlled-extractions, especially in Class I cases, orthodontic or prosthetic treatments, which may require extra time, cost and effort, could be prevented and a conceivable occlusion can be established.

Relationship of third molar movement during orthodontic treatment and root angulation

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Morteza Oshagh

2012-01-01

Conclusion: The relation between the amount of third molar movement and its root angulation was not statistically significant. Therefore movement of third molars during orthodontic treatment should not be assumed as an etiologic factor of root angulations.

Clinician-related factors behind the decision to extract an asymptomatic lower third molar. A cross-sectional study based on Spanish and Portuguese dentists.

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Alves-Pereira, D; Pereira-Silva, D; Figueiredo, R; Gay-Escoda, C; Valmaseda-Castellón, E

2017-09-01

Scientific literature estimates that around 18 to 40 % of asymptomatic third molars are extracted. The aims of the present study were to determine the indications for extraction of asymptomatic lower third molars in a sample of Spanish and Portuguese dentists, and to relate these indications to the clinicians' training and professional experience. A survey consisting of 15 cases of asymptomatic lower third molars was emailed to Portuguese and Spanish dentists. The clinicians were asked to assess the level of difficulty of the extractions and to make a reasoned recommendation based on the panoramic radiographs, gender and age of the patients. 381 clinicians filled in the questionnaires. Most of the professionals had over 13 years of clinical experience. The number of Spanish clinicians with postgraduate degrees in Oral Surgery was significantly higher. On average, 42% of respondents recommended extraction of asymptomatic third molars. The indication for extraction was significantly higher among Portuguese dentists. Clinical experience was negatively correlated with the perceived extraction difficulty (pPortuguese dentists were more in favour of removing asymptomatic lower third molars than the Spanish dentists, although the latter had a higher proportion of professionals with postgraduate studies in Oral Surgery.

Molar development in sheep: morphology, radiography, microhardness

International Nuclear Information System (INIS)

Milhaud, G.; Nezit, J.

1991-01-01

The chronology of molar development is studied from radiographic and macroscopic observations on 48 south Pre-Alps were living under optimal nutritional conditions. It was found that the first molar started its development in utero, the second molar at one month after birth, and the third molar, at 9-10 months. The first molar emerged into the oral cavity at 3 months, the second at 9 months and the third molar at 18 months. The first molar began the development of its roots at 6-7 months, the second molar at 11-12 months and the third molar at 20-22 months. The first molar reached completion of the growth of its roots at 3.5-4 years, the second and the third molars at about 6 years. The molars show the particularity of being functional during the three months which follow their eruption although the development of the crown is not completed. Then the accelerated wear is only partially compensated by the growth of the roots. The study also shows how the combined effects of wear and dentine deposit in the pulp cavity affect the morphology of molars. It reveals the marked hardness of enamel (240 Vickers units) and the low resistance of dentine at the surface of attrition (30 Vickers units)

Estudio de volumen molar y refracción molar de miscelas de triglicéridos (triacetina, tributirina o tricaprilina) y alcoholes (etanol, 1-butanol o 1-hexanol)

OpenAIRE

Rodríguez Rodríguez, M.; Galán Vallejo, M.; Muñoz Cueto, María J.

1992-01-01

Values of molar refraction for every studied mixtures show linear plots versus molar fractions of triglyceride. Values of molar volume show this behaviour, but only for tributyrin-butanol or tricaprylin-butanol miscellas. However, in tributyrin-ethanol mixtures, volume contractions have been found, whereas triacetin-butanol and tributyrin-hexanol show volume expansions. These facts are related to the mode of being structured of the alcohol and triglyceride molecules in mixtures. A linea...

Evaluation of NO2 predictions by the plume volume molar ratio method (PVMRM) and ozone limiting method (OLM) in AERMOD using new field observations.

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Hendrick, Elizabeth M; Tino, Vincent R; Hanna, Steven R; Egan, Bruce A

2013-07-01

The U.S. Environmental Protection Agency (EPA) plume volume molar ratio method (PVMRM) and the ozone limiting method (OLM) are in the AERMOD model to predict the 1-hr average NO2/NO(x) concentration ratio. These ratios are multiplied by the AERMOD predicted NO(x) concentration to predict the 1-hr average NO2 concentration. This paper first briefly reviews PVMRM and OLM and points out some scientific parameterizations that could be improved (such as specification of relative dispersion coefficients) and then discusses an evaluation of the PVMRM and OLM methods as implemented in AERMOD using a new data set. While AERMOD has undergone many model evaluation studies in its default mode, PVMRM and OLM are nondefault options, and to date only three NO2 field data sets have been used in their evaluations. Here AERMOD/PVMRM and AERMOD/OLM codes are evaluated with a new data set from a northern Alaskan village with a small power plant. Hourly pollutant concentrations (NO, NO2, ozone) as well as meteorological variables were measured at a single monitor 500 m from the plant. Power plant operating parameters and emissions were calculated based on hourly operator logs. Hourly observations covering 1 yr were considered, but the evaluations only used hours when the wind was in a 60 degrees sector including the monitor and when concentrations were above a threshold. PVMRM is found to have little bias in predictions of the C(NO2)/C(NO(x)) ratio, which mostly ranged from 0.2 to 0.4 at this site. OLM overpredicted the ratio. AERMOD overpredicts the maximum NO(x) concentration but has an underprediction bias for lower concentrations. AERMOD/PVMRM overpredicts the maximum C(NO2) by about 50%, while AERMOD/OLM overpredicts by a factor of 2. For 381 hours evaluated, there is a relative mean bias in C(NO2) predictions of near zero for AERMOD/PVMRM, while the relative mean bias reflects a factor of 2 overprediction for AERMOD/OLM. This study was initiated because the new stringent 1-hr NO2

Association of the Mandibular Third Molar Position to the Pericoronitis

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Tsvetan Tsvetanov

2018-02-01

Full Text Available Introduction: Pericoronitis is inflammation of the soft tissues surrounding the crown of a partially erupted tooth. Objective: To provide measurement of lower third molar angulation and determine relationship between mandibular third molar position and presence of pericoronitis. Material and methods: We studied 104 patients with lower third molar pericoronitis with clinical manifestations and measurement of lower third molar angulation. The mean age of patients was 25.7 years (range 18-35 years. Results: In this study was used the following statistical analysis, Pearson correlation coefficient and Spearman’s correlation coefficient (nonparametric version of the Pearson correlation coefficient for measure of the linear correlation between two variables - pericoronitis and angulation of the lower third molars. The chi-square test was used to assesses case incidences. The level of significance was p<0.05. 36.04% of partially impacted mandibular third molars were mesioangular followed by the vertical (25.47%, horizontal (18.97%, distoangular (9.21%, buccal (5.42% and lingual (3.79% position. The lowest part of the mandibular third molars is located in the ramus of mandible (1.08%. The present study was found in relation to mesioangular, distoangular, vertical impaction and pericoronitis (p<0.05. Conclusion: We conclude that the position of lower third molar may be able to be associated with presence of pericoronitis.

Effects of H2O/Na2O molar ratio on the strength of alkaline activated ground blast furnace slag-ultrafine palm oil fuel ash based concrete

International Nuclear Information System (INIS)

Yusuf, Moruf Olalekan; Megat Johari, Megat Azmi; Ahmad, Zainal Arifin; Maslehuddin, Mohammed

2014-01-01

Highlights: • Effects of H 2 O/Na 2 O on GBFS-POFA alkaline activated concrete are investigated. • High H 2 O/Na 2 O contents enhance dissolutions/workability at the expense of strength. • Lower H 2 O/Na 2 O molar ratios aid compressive strength of the products. • Increase in H 2 O/Na 2 O favours the reactivity of Ca and the products molecular bonds. • Low H 2 O/Na 2 O positively affects the microstructural density of the products. - Abstract: Effects of H 2 O/Na 2 O molar ratios (MRs) on the developed alkaline activated pozzolanic solid wastes (PMs)-ultrafine palm oil fuel ash (UPOFA) and ground blast furnace slag (GBFS)-were studied by using the constant mass of combined activators (10 M NaOH aq + Na 2 SiO 3aq of silica-modulus (Ms = SiO 2 /Na 2 O) of 3.3).The free water content (FWC) expressed as FWC/(PMs) varied from 0.02 to 0.1 by mass while the total H 2 O/Na 2 O MRs ranged from 18.9 to 23.1 The findings revealed that increase in H 2 O/Na 2 O MRs negatively affects the strength but positively impact the mixture workability (consistency). The microstructural morphology examination using Scanning Electron Microscope coupled with Energy dispersive spectroscopy (SEM + EDS) reveals the contribution of H 2 O/Na 2 O MRs to the product nature, compactness, and the reactivity of Ca 2+ and Al 3+ while Fourier transform infra-red (FTIR) spectroscopy indicates that H 2 O/Na 2 O ratios contributed to the product amorphousity and carbonation process but sparingly affected its formed polymerized structural units (SiQ n (mAl), n = 2 and 3)

Prevalent of root resorption of second molar adjustment the impacted third molar in prepiacal and panoramic radiographs

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Mohammad Ebrahimi Saravi

2013-10-01

Full Text Available   Background and Aims: Impacted third molar reduces the bone level in the distal aspect of second molar, and sometimes it can lead to root resorption of the adjacent tooth. The purpose of this study was to determine this resorption using panoramic and periapical radiographs.   Materials and Methods: In this cross-sectional descriptive study 54 patient (28 men, 26 women above 15 years old with the average of 22 years in Oral and Maxillofacial Department of Tehran University were studied. A periapical radiography from the third molar and a panoramic radiograph were taken from each patient (Because of their routine use and evaluation of accuracy of panoramic compared with periapical, and the magnitude of the root resorption for the second molar was determined by 2 observers and written in a questionnaire. Data were analyzed using Fisher test.   Results: The prevalence of the root resorption of the second molar adjacent to the impacted third molar in the panoramic and the periapical radiographies, with respect to the limitation of the sample size were 46.3% and 31.5%, respectively, with 95% confidence(P>0.05. Most of these resorptions were in the cervical third of the second molar roots and in cases in which the third molars were mesially oriented or horizontal. There was also no significant difference between panoramic and periapical radiographs.   Conclusion: Due to the increased risk of the resorption of the second molar adjacent to the third molar, extraction of the impacted third molars, especiall y mesially oriented or horizontal ones are recommended.

Presence of third molars in orthodontic patients from northern Greece

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Barka G

2012-05-01

Full Text Available Georgia Barka,1 Georgios Tretiakov,1 Theodosios Theodosiou,2 Ioulia Ioannidou-Marathiotou31School of Dentistry, 2Biostatistics, Department of Informatics, School of Natural Sciences, 3Department of Orthodontics, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, GreeceObjective: 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 Χ2 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.Keywords: third molars, presence, orthodontic population, Greeks

Barium recovery by crystallization in a fluidized-bed reactor: effects of pH, Ba/P molar ratio and seed.

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Su, Chia-Chi; Reano, Resmond L; Dalida, Maria Lourdes P; Lu, Ming-Chun

2014-06-01

The effects of process conditions, including upward velocity inside the column, the amount of added seed and seed size, the pH value of the precipitant or the phosphate stream and the Ba/P molar ratio in a fluidized-bed reactor (FBR) were studied with a view to producing BaHPO₄ crystals of significant size and maximize the removal of barium. XRD were used to identify the products that were collected from the FBR. Experimental results show that an upward velocity of 48 cmmin(-1) produced the largest BaHPO₄ crystals with a size of around 0.84-1.0mm. The addition of seed crystals has no effect on barium removal. The use of a seed of a size in the ranges unseededbarium was removed at pH 8.4-8.6 and [Ba]/[P]=1.0. The XRD results show that a significant amount of barium phosphate (Ba₃(PO₄)₂) was obtained at pH 11. The compounds BaHPO₄ and BaO were present at a pH of below 10. Copyright © 2014 Elsevier Ltd. All rights reserved.

Less is More: A Comparison of Antibody-Gold Nanoparticle Conjugates of Different Ratios.

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Byzova, Nadezhda A; Safenkova, Irina V; Slutskaya, Elvira S; Zherdev, Anatoly V; Dzantiev, Boris B

2017-11-15

This comprehensive study is related to gold nanoparticles (GNPs) conjugated with antibodies. The goal of the study is to determine the minimal concentration of antibodies for conjugate synthesis when the conjugates have high antigen-capturing activity. Two systems were studied: gold nanoparticles conjugated with monoclonal antibodies (mAb-GNP) specific to Helicobacter pylori and gold nanoparticles conjugated with polyclonal antibodies (pAb-GNP) specific to mouse immunoglobulins. Several conjugates were synthesized with different GNP-to-antibody molar ratios (from 1:1 to 1:245) through nondirectional and noncovalent immobilization on a surface of GNPs with a diameter of 25.3 ± 4.6 nm. The maximal antigen-capturing activities and equilibrium constants of the conjugates correlate with the formation of a constant hydrodynamic radius of the conjugates for mAb-GNP (GNP to antibody molar ratio 1:58) and with the stabilizing concentration by flocculation curves for pAb-GNP (GNP to antibody molar ratio 1:116). The application of the conjugates to the lateral flow immunoassay shows that the antibody concentrations used for the conjugation can be reduced (below the stabilizing concentration) without losing activity for the mAb-GNP conjugates. The findings highlight that the optimal concentration of antibodies immobilized on the surface of GNPs is not always equal to the stabilizing concentration determined by the flocculation curve.

Actitud terapéutica ante sacos foliculares de terceros molares incluídos Therapeutic approach to impacted third molar follicles

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R. González García

2005-04-01

Full Text Available El quiste dentígero o folicular es un quiste odontogénico del desarrollo. Está revestido por el epitelio del folículo dentario, y suele estar en relación con un diente permanente incluído. Presentamos el caso clínico de un paciente en el que se observa la aparición de un quiste dentígero a partir del saco folicular de un tercer molar incluído no exodonciado, y lo comparamos con la evolución de un cordal incluído y su saco folicular contralaterales en los que se realizó la exodoncia. El tratamiento definitivo del quiste dentígero asociado a un tercer molar incluído es quirúrgico, con la exodoncia de la pieza y enucleación del quiste. Los sacos foliculares mayores de 2 mm asociados a terceros molares incluídos evolucionan en numerosas ocasiones a quistes foliculares. Está indicada la exodoncia de dichos cordales para evitar la evolución a quiste dentígero.The dentigerous cyst or follicular cyst is a developmental odontogenic cyst. It is covered by the epithelium of the dental follicle, and it tends to be related to an impacted permanent tooth. The case report of a patient who was seen to develop a dentigerous cyst arising from the follicle of an impacted non-extracted third molar is presented. This is then compared with the evolution of the contralateral impacted third molar and its follicle that was extracted. The definitive treatment for a dentigerous cyst associated with an impacted third molar is surgical, the extraction of the tooth and enucleation of the cyst. Follicles measuring more+ than 2 mm and that are associated with impacted third molars often develop into follicular cysts. The extraction of these third molars is indicated in order to avoid the development of a dentigerous cyst

Estudio de volumen molar y refracción molar de miscelas de triglicéridos (triacetina, tributirina o tricaprilina y alcoholes (etanol, 1-butanol o 1-hexanol

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Rodríguez Rodríguez, M.

1992-12-01

Full Text Available Values of molar refraction for every studied mixtures show linear plots versus molar fractions of triglyceride. Values of molar volume show this behaviour, but only for tributyrin-butanol or tricaprylin-butanol miscellas. However, in tributyrin-ethanol mixtures, volume contractions have been found, whereas triacetin-butanol and tributyrin-hexanol show volume expansions. These facts are related to the mode of being structured of the alcohol and triglyceride molecules in mixtures. A linear relationship between molar volume and temperature have been found, and also a linear dependence between the coefficient of thermal expansion at constant pressure and the molar fraction of triglyceride.

Los valores de la refracción molar en todas las miscelas estudiadas presentan variaciones lineales frente a la fracción molar de triglicérido. la misma variación que presentan los valores del volumen molar de las miscelas tributirina y tricaprilina en butanol. Sin embargo, en las miscelas de tributirina-etanol se encuentran contracciones de volumen mientras que en las de triacetina-butanol y tributirina-hexanol expansiones, atribuidas en ambos casos a la forma de estructurarse las moléculas de alcohol y triglicérido en las miscelas. Por otra parte, se encuentra una variación lineal entre el volumen molar de las miscelas y la temperatura, y se establece una relación lineal entre el coeficiente de dilatación térmico molar a presión constante y la fracción molar de triglicérido en los cinco sistemas estudiados.

C:N:P Molar Ratios, Sources and 14C Dating of Surficial Sediments from the NW Slope of Cuba.

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Guadalupe de la Lanza Espino

Full Text Available The surficial sediments recovered from 12 sites located near the channel axis of the Florida Straits and the lower slope off NW Cuba were analyzed for total organic carbon (TOC, nitrogen (TN, phosphorus (TP, elemental C:N:P ratios, C and N isotopic values, and 14C dating. The depth profiles of TOC, TN, and TP (0-18 cm displayed a downcore trend and a significant variation. The TOC values were low (0.15 to 0.62%; 66 to 516 µmol g(-1. Sites near the island's lower slope had lower TOC average concentrations (158-333 µmol g(-1 than those closer to the channel axis (averaging 341-516 µmol g(-1; p <0.05. The TN concentrations near the lower slope attained 0.11% (80 µmol g(-1, whereas, towards the channel axis, they decreased to 0.07% (55 µmol g(-1; p<0.05. The C:N ratios ranged from 1.9 to 10.2. The mean molar C:N ratio (5.4 indicated a marine hemipelagic deposition. The TP was lower at sites near the lower slope (38.4 to 50.0 µmol gv; 0.12% to 0.16% than those near the channel axis (50.0 to 66 µmol g(-1; 0.15 to 0.21%. C:P fluctuated from 7.7 to 14.1 in the surficial sediment layer. The bulk organic δ13Corg and δ15N values confirmed pelagic organic sources, and the 14C dating revealed that the sediments were deposited during the Holocene (1000-5000 yr BP. We suggest that the hydrodynamic conditions in the Straits influence vertical and advective fluxes of particulate organic material trapped in the mixed-layer, which reduces the particulate matter flux to the seabed.

Acute inflammation in horizontal incompletely impacted third molar with radiolucency in the elderly

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Minoru Yamaoka

2009-07-01

Full Text Available Minoru Yamaoka, Yusuke Ono, Masahiro Takahashi, Masahide Ishizuka, Takayuki Uchihashi, Kouichi Yasuda, Takashi Uematsu, Kiyofumi FurusawaMatsumoto Dental University, Oral and Maxillofacial Surgery, Shiojiri, Nagano, JapanAbstract: Although radiolucency has been shown as a risk of infection, the poorly understood effects of aging on radiolucency correlate with acute pericoronitis, which has a high risk of infection extending any complications. We reviewed the records of 346 consecutive patients aged more than 41 years to evaluate whether pericoronal radiolucency below the crown in mandibular horizontal incompletely impacted third molars is related to acute inflammation. The frequency of acute inflammation in teeth with pericoronal radiolucency below the crown was similar to that in teeth without; however, the odds ratio of acute inflammation exhibited in women aged more than 61 years compared to women aged 41–50 years was 9.77 (95% confidence interval [CI]: 1.67–57.29; P <<0.05, and in women aged more than 61 years compared to women aged 51–60 years was 26.25 (95% CI: 2.94–234.38; P < 0.01. The odds ratio of severe acute inflammation exhibited in men aged more than 61 years compared to men aged 41–50 years was 16.67 (95% CI: 1.76–158.27; P < 0.01. These odds ratios indicate an association of acute pericoronitis, including the severe forms of acute inflammation that result from pericoronitis, with pericoronal radiolucency below the crown in the elderly.Keywords: radiolucency, mandible, third molar, acute inflammation, aging

Thermodynamic interrelation between excess limiting partial molar characteristics of a liquid nonelectrolyte

International Nuclear Information System (INIS)

Ivanov, Evgeniy V.

2012-01-01

Highlights: ► Excess limiting molar volume may be regarded as a solvation-related characteristic. ► Volumetric and enthalpic effects of dissolution are interrelated thermodynamically. ► Possibility to estimate the partial change in solute compressibility is described. - Abstract: On the basis of thermodynamic analysis, it is concluded that the excess limiting partial molar volume, like the excess limiting partial molar enthalpy, can be considered as a solvation-related characteristic of a liquid nonelectrolyte. A thermodynamically grounded interrelation between standard volumetric and enthalpic effects of solution of a liquid nonelectrolyte (or series of nonelectrolytes) is suggested.

Lower zinc bioavailability may be related to higher risk of subclinical atherosclerosis in Korean adults.

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Su Kyoung Jung

Full Text Available BACKGROUND: There is a proposed link between dietary zinc intake and atherosclerosis, but this relationship remains unclear. Phytate may contribute to this relationship by influencing zinc bioavailability. OBJECTIVE: The aim of this study is to examine the relationship between zinc bioavailability and subclinical atherosclerosis in healthy Korean adults. MATERIALS AND METHODS: The present cross-sectional analysis used baseline data from the Korean multi-Rural Communities Cohort Study (MRCohort, which is a part of The Korean Genome Epidemiology Study (KoGES. A total of 5,532 subjects (2,116 men and 3,416 women aged 40 years and older were recruited from rural communities in South Korea between 2005 and 2010. Phytate:zinc molar ratio, estimated from a food-based food frequency questionnaire (FFQ of 106 food items, was used to determine zinc bioavailability, and carotid intima media thickness (cIMT and pulse wave velocity (PWV were measured to calculate the subclinical atherosclerotic index. RESULTS: We found that phytate:zinc molar ratio is positively related to cIMT in men. A higher phytate:zinc molar ratio was significantly related to an increased risk of atherosclerosis in men, defined as the 80(th percentile value of cIMT (5(th vs. 1(st quintile, OR = 2.11, 95% CI 1.42-3.15, P for trend = 0.0009, and especially in elderly men (5(th vs. 1(st quintile, OR = 2.58, 95% CI 1.52-4.37, P for trend = 0.0021. We found a positive relationship between phytate:zinc molar ratio and atherosclerosis risk among women aged 65 years or younger. Phytate:zinc molar ratio was not found to be related to PWV. CONCLUSIONS: Lower zinc bioavailability may be related to higher atherosclerosis risk.

Effect of different processes and Ti/Zn molar ratios on the structure, morphology, and enhanced photoelectrochemical and photocatalytic performance of Ti3+ self-doped titanium-zinc hybrid oxides

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Fu, Rongrong; Wang, Qingyao; Gao, Shanmin; Wang, Zeyan; Huang, Baibiao; Dai, Ying; Lu, Jun

2015-07-01

Ti3+ self-doped titanium-zinc hybrid oxides with different phase compositions and morphologies were successfully synthesized using Zn powder as the reductant and Zn source by a chemical-reduction precipitation method with subsequent thermal treatment. The fabricated Ti3+ self-doped TiO2(A)/TiO2(R), TiO2(A)/TiO2(R)/ZnTiO3, and TiO2(A)/ZnO heterojunctions were characterized by X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The effects of various Ti/Zn molar ratios and preparation processes on the structural, morphological, optical, photocurrent and photocatalytic properties of the resultant samples were investigated systematically. Results reveal that Ti3+ self-doping enhances the photoabsorption capability of titanium-zinc hybrid oxides in the visible-light region. Moreover, different processes and Ti/Zn molar ratios play great influences on the structure, morphology, optical, photocurrent and photocatalytic properties of the final products. Ti3+ self-doped titanium-zinc hybrid oxides exhibit excellent photocurrent and photocatalytic activity than pure TiO2 and ZnTiO3 under visible-light irradiation (λ ≥ 400 nm). The most active Ti3+ self-doped titanium-zinc hybrid oxides photoanode presents significantly improved water splitting performance. The synergistic effect between the Ti3+ self-doped and heterojunctions is responsible for the enhanced performance of these materials.

New quantitative classification of the anatomical relationship between impacted third molars and the inferior alveolar nerve

International Nuclear Information System (INIS)

Wang, Wei-Quan; Chen, Michael Y. C.; Huang, Heng-Li; Fuh, Lih-Jyh; Tsai, Ming-Tzu; Hsu, Jui-Ting

2015-01-01

Before extracting impacted lower third molars, dentists must first identify the spatial relationship between the inferior alveolar nerve (IAN) and an impacted lower third molar to prevent nerve injury from the extraction. Nevertheless, the current method for describing the spatial relationship between the IAN and an impacted lower third molar is deficient. Therefore, the objectives of this study were to: (1) evaluate the relative position between impacted lower third molars and the IAN; and (2) investigate the relative position between impacted lower third molars and the IAN by using a cylindrical coordinate system. From the radiology department’s database, we selected computed tomography images of 137 lower third molars (from 75 patients) requiring removal and applied a Cartesian coordinate system by using Mimics, a medical imaging software application, to measure the distribution between impacted mandibular third molars and the IAN. In addition, the orientation of the lower third molar to the IAN was also measured, but by using a cylindrical coordinate system with the IAN as the origin. According to the Cartesian coordinate system, most of the IAN runs through the inferior side of the third molar (78.6 %), followed by the lingual side (11.8 %), and the buccal side (8.9 %); only 0.7 % is positioned between the roots. Unlike the Cartesian coordinate system, the cylindrical coordinate system clearly identified the relative position, r and θ, between the IAN and lower third molar. Using the cylindrical coordinate system to present the relationship between the IAN and lower third molar as (r, θ) might provide clinical practitioners with a more explicit and objective description of the relative position of both sites. However, comprehensive research and cautious application of this system remain necessary

Radiographic evaluation of third molar development in 6 to 24 year olds

International Nuclear Information System (INIS)

Jung, Yun Hwa; Cho, Bong Hae

2014-01-01

This study investigated the developmental stages of third molars in relation to chronological age and compared third molar development according to location and gender. A retrospective analysis of panoramic radiographs of 2490 patients aged between 6 and 24 years was conducted, and the developmental stages of the third molars were evaluated using the modified Demirjian's classification. The mean age, standard deviation, minimal and maximal age, and percentile distributions were recorded for each stage of development. A Mann-Whitney U test was performed to test the developmental differences in the third molars between the maxillary and mandibular arches and between genders. A linear regression analysis was used for assessing the correlation between the third molar development and chronological age. The developmental stages of the third molars were more advanced in the maxillary arch than the mandibular arch. Males reached the developmental stages earlier than females. The average age of the initial mineralization of the third molars was 8.57 years, and the average age at apex closure was 21.96 years. The mean age of crown completion was 14.52 and 15.04 years for the maxillary and the mandibular third molars, respectively. The developmental stages of the third molars clearly showed a strong correlation with age. The third molars developed earlier in the upper arch than the lower arch; further, they developed earlier in males than in females.

Effect of molar ratios of MgO/Al{sub 2}O{sub 3} on the sintering behavior and thermal shock resistance of MgOAl{sub 2}O{sub 3}SiO{sub 2} composite ceramics

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Feng, Dong, E-mail: 1078155409@qq.com [School of High Temperature Materials and Magnesium Resource Engineering, University of Science and Technology Liaoning, Anshan 114051 (China); Luo, Xudong, E-mail: luoxudongs@aliyun.com [School of High Temperature Materials and Magnesium Resource Engineering, University of Science and Technology Liaoning, Anshan 114051 (China); Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Zhang, Guodong [School of High Temperature Materials and Magnesium Resource Engineering, University of Science and Technology Liaoning, Anshan 114051 (China); Xie, Zhipeng [Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

2017-01-01

In order to determine the relationship between the property of MgOAl{sub 2}O{sub 3}SiO{sub 2} composite ceramics and molar ratios of MgO/Al{sub 2}O{sub 3}, especially the sintering behavior and thermal shock resistance, the MgOAl{sub 2}O{sub 3}SiO{sub 2} composite ceramics were fabricated with micro-size MgO, Al{sub 2}O{sub 3} powder and nano-size SiO{sub 2} as main raw materials. The sample was characterized by phase analysis, densification and thermal shock times. Moreover, field emission scanning electron microscope was also conducted to study microstructure of the samples before and after thermal shock. Effect of different molar ratios of MgO/Al{sub 2}O{sub 3} on the sintering behavior and thermal shock resistance of composite ceramics were investigated. The results showed that the sample possess better sintering behavior and thermal shock resistance with the molar ratio of MgO/Al{sub 2}O{sub 3} equal to 2/1. Grains of periclase and spinel were directly bonded together, resulting in a dense and compact microstructure, and the bulk density of obtained sample reached 3.4 g/cm{sup 3}. The microstructure of sample after thermal shock revealed that the crack propagation path was deflected and bifurcated, the main-crack propagation was restricted and more fracture energy was consumed, the thermal shock resistance of composite ceramics was greatly improved. - Highlights: • Effect of MgO/Al{sub 2}O{sub 3} on the composite ceramic was firstly researched with 1 mol% SiO{sub 2}. • Microcracks for a short distance by interlinking can eliminate the crack propagation. • The composite ceramic have optimal synthetic property with MgO/Al{sub 2}O{sub 3} was 2/1.

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

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

2016-01-01

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

MANAGEMENT OF MANDIBULAR THIRD MOLAR SURGERY TO PRESERVE PERIODONTAL HEALTH OF SECOND MOLAR

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Elitsa G. Deliverska

2017-06-01

Full Text Available Background: Extraction of impacted third molar violates surrounding soft and bony tissues. Various surgical approaches and surgical technics have an important impact on the periodontal health of the adjacent second molar. Purpose: The aim of this review is to analyse the causes that can affect postoperative periodontal outcomes for the mandibular second molars (LM2 adjacent to the impacted/ semi impacted mandibular third molars (LM3. Material and Methods: Electronic searches were conducted through the MEDLINE (PubMed, Scopus, etc. databases to screen all relevant articles published from inception to April 2017. Results: Different flap techniques had no significant impact on the probing depth reduction or on the clinical attachment level of LM2. Szmyd and paramarginal flap designs may be the most effective in reducing the probing depth after third molar surgery, and the envelope flap may be the least effective. Use of bone substitutes and guided tissue regeneration therapy has been proposed, to eliminate or prevent these periodontal defects, but there is still no consensus on their predictability or clinical benefit. Higher costs and the risk of postoperative inflammatory complications should also be taken into proper account, as with any surgical procedure. “Orthodontic extraction” is indicated for that impacted M3 that present a high risk of postoperative periodontal defects at the distal aspect of adjacent M2. Conclusion: Risk factors associated with bone loss following lower third molar extraction includes age, the direction of the eruption, preoperative bone defects, and resorbtion of the LM2 root surface. Prevention of such periodontal defects continues to challenge clinicians.

Incidence of root canal treatment of second molars following adjacent impacted third molar extraction

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Yener Oguz

2016-03-01

Conclusion: Although the incidence is minimal, iatrogenic subluxation injuries occurring during the surgical removal of impacted third molars can lead to pulpal complications and a requirement for root canal treatment of adjacent second molars.

Root canal morphology of primary molars: a micro-computed tomography study.

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Fumes, A C; Sousa-Neto, M D; Leoni, G B; Versiani, M A; da Silva, L A B; da Silva, R A B; Consolaro, A

2014-10-01

This was to investigate the root canal morphology of primary molar teeth using micro-computed tomography. Primary maxillary (n = 20) and mandibular (n = 20) molars were scanned at a resolution of 16.7 μm and analysed regarding the number, location, volume, area, structured model index (SMI), area, roundness, diameters, and length of canals, as well as the thickness of dentine in the apical third. Data were statistically compared by using paired-sample t test, independent sample t test, and one-way analysis of variance with significance level set as 5%. Overall, no statistical differences were found between the canals with respect to length, SMI, dentine thickness, area, roundness, and diameter (p > 0.05). A double canal system was observed in the mesial and mesio-buccal roots of the mandibular and maxillary molars, respectively. The thickness in the internal aspect of the roots was lower than in the external aspect. Cross-sectional evaluation of the roots in the apical third showed flat-shaped canals in the mandibular molars and ribbon- and oval-shaped canals in the maxillary molars. External and internal anatomy of the primary first molars closely resemble the primary second molars. The reported data may help clinicians to obtain a thorough understanding of the morphological variations of root canals in primary molars to overcome problems related to shaping and cleaning procedures, allowing appropriate management strategies for root canal treatment.

A rare case of retained fourth molar teeth in maxilla and mandible. Case report

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Rahnama Mansur

2014-06-01

Full Text Available The study presents a case of the rarely occurring totally retained fourth molar teeth simultaneously in maxilla and mandible. The appearance of supernumerary teeth is a relatively uncommon dental anomaly and it is rare for patients to have impacted fourth molars in two quadrant. The aim of this work is to describe the presence of unilateral (right fourth molars in the maxilla and the mandible in a young female patient aged 24 years. Orthopantomogram revealed impacted lower third molars but also unerupted unilateral (right upper and lower fourth molars. Before orthodontic treatment, the patient was subsequently admitted for removal of third and fourth impacted upper and lower molars under local anesthesia.

Third molar mineralization in relation to chronologic age estimation of the Han in central southern China.

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Liu, Ying; Geng, Kun; Chu, Yanhao; Xu, Mindi; Zha, Lagabaiyila

2018-03-03

The purpose of this study is to provide a forensic reference data about estimating chronologic age by evaluating the third molar mineralization of Han in central southern China. The mineralization degree of third molars was assessed by Demirjian's classification with modification for 2519 digital orthopantomograms (1190 males, 1329 females; age 8-23 years). The mean ages of the initial mineralization and the crown completion of third molars were around 9.66 and 13.88 years old in males and 9.52 and 14.09 years old in females. The minimum ages of apical closure were around 16 years in both sexes. Twenty-eight at stage C and stage G and 38 and 48 at stage F occurred earlier in males than in females. There was no significant difference between maxillary and mandibular teeth in males and females except that stage C in males. Two formulas were devised to estimate age based on mineralization stages and sexes. In Hunan Province, the person will probably be over age 14, when a third molar reaches the stage G. The results of the study could provide reference for age estimation in forensic cases and clinical dentistry.

Radiographic evaluation of third molar development in 6- to 24-year-olds

Science.gov (United States)

Jung, Yun-Hoa

2014-01-01

Purpose This study investigated the developmental stages of third molars in relation to chronological age and compared third molar development according to location and gender. Materials and Methods A retrospective analysis of panoramic radiographs of 2490 patients aged between 6 and 24 years was conducted, and the developmental stages of the third molars were evaluated using the modified Demirjian's classification. The mean age, standard deviation, minimal and maximal age, and percentile distributions were recorded for each stage of development. A Mann-Whitney U test was performed to test the developmental differences in the third molars between the maxillary and mandibular arches and between genders. A linear regression analysis was used for assessing the correlation between the third molar development and chronological age. Results The developmental stages of the third molars were more advanced in the maxillary arch than the mandibular arch. Males reached the developmental stages earlier than females. The average age of the initial mineralization of the third molars was 8.57 years, and the average age at apex closure was 21.96 years. The mean age of crown completion was 14.52 and 15.04 years for the maxillary and the mandibular third molars, respectively. Conclusion The developmental stages of the third molars clearly showed a strong correlation with age. The third molars developed earlier in the upper arch than the lower arch; further, they developed earlier in males than in females. PMID:25279338

The origin of the lower fourth molar in canids, inferred by individual variation

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Masakazu Asahara

2016-11-01

Full Text Available Background An increase in tooth number is an exception during mammalian evolution. The acquisition of the lower fourth molar in the bat-eared fox (Otocyon megalotis, Canidae, Carnivora, Mammalia is one example; however, its developmental origin is not clear. In some canids (Canidae, individual variation exist as supernumerary molar M4. This study focuses on the acquisition of the lower fourth molar in canids and proposes that the inhibitory cascade model can explain its origin. Methods Occlusal view projected area of lower molars was determined from 740 mandibles obtained from Canis latrans, Nyctereutes procyonoides, and Urocyon cinereoargenteus museum specimens. For each molar, relative sizes of molars (M2/M1 and M3/M1 scores affected by inhibition/activation dynamics during development, were compared between individuals with and without supernumerary molar (M4. Results Possession of a supernumerary molar was associated with significantly larger M2/M1 score in Canis latrans, M3/M1 score in Nyctereutes procyonoides, and M2/M1 and M3/M1 scores in Urocyon cinereoargenteus compared to individuals of these species that lacked supernumerary molars. Discussion We propose that, in canids, the supernumerary fourth molar is attributable to reduced inhibition and greater activation during molar development. In the bat-eared fox, altered inhibition and activation dynamics of dental development during omnivorous-insectivorous adaptation may be a contributing factor in the origin of the lower fourth molar.

Glycerol capped PbS/CdS core/shell nanoparticles at different molar ratio and its application in biosensors: An optical properties study

Energy Technology Data Exchange (ETDEWEB)

Das, D., E-mail: ddasphy014@gmail.com; Hussain, A. M. P. [Department of Physics, Cotton College, Guwahati, Assam, India- 781001 (India)

2016-05-06

Glycerol capped PbS/CdS core/shell type nanoparticles fabricated with two different molar ratios are characterized for study of structural and optical properties. The X-ray diffraction (XRD) pattern exhibits cubic phased polycrystalline nanocrystals. The calculated grain sizes from Williamson-Hall plot were found to be around 6 nm with increased strain. HRTEM investigation confirms the formation of core/shell nanostructures and the sizes of the particles were found to be around 7 nm which is in good agreement with the results of the W-H plot. An increase of band gap with the decrease in precursor concentration is confirmed from the blue shift in the absorption spectra and also from Tauc plot. A clear blue shifted intense emission is observed in the photoluminescence spectra with decrease in particle size. Intense luminescence from the core/shell nanostructure may be applied in bio labelling and biosensors.

Demineralization of Enamel in Primary Second Molars Related to Properties of the Enamel

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N. Sabel

2012-01-01

Full Text Available Enamel structure is of importance in demineralization. Differences in porosity in enamel effect the rate of demineralization, seen between permanent and deciduous teeth. Individual differences have been shown in the mean mineral concentration values in enamel, the role of this in demineralization is not thoroughly investigated. The aim of this study was to study variations of depths of artificial lesions of demineralization and to analyze the depth in relation to variations in the chemical and mineral composition of the enamel. A demineralized lesion was created in second primary molars from 18 individuals. Depths of lesions were then related to individual chemical content of the enamel. Enamel responded to demineralization with different lesion depths and this was correlated to the chemical composition. The carbon content in sound enamel was shown to be higher where lesions developed deeper. The lesion was deeper when the degree of porosity of the enamel was higher.

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

Science.gov (United States)

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

2012-09-01

Adolescence is a relatively short period between childhood and adulthood. It is very difficult to determine adulthood based on biological indicators. The third molar may be considered a potential age marker for the period between the ages of 16-21. Our study evaluated a set of 1700 panoramic radiographs of individuals aged between 5 and 21 years. Results confirmed the statistically significant difference in the course of third molars development. The mean deviation for individuals with one third molar agenesis is -0.98 years, for individuals with two third molars agenesis -1.89 years, and with three molars agenesis -3.28 years. Thus, the extent of the deviation is directly proportional to the number of unformed third molars. The calculation of age according to the mean of stages of all third molars could lead to the underestimation of age. No intergender differences were found. Age determination using third molars could be used for forensic purposes. © 2012 American Academy of Forensic Sciences.

Fracture behavior of human molars.

Science.gov (United States)

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

2012-12-01

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

Standard molar enthalpies of formation and of sublimation of the terphenyl isomers

International Nuclear Information System (INIS)

Ribeiro da Silva, Manuel A.V.; Santos, Luis M.N.B.F.; Lima, Luis M. Spencer S.

2008-01-01

The standard (p 0 = 0.1 MPa) molar enthalpies of formation in the crystalline phases of ortho, meta and para-terphenyl isomers, at T = 298.15 K, were derived from the standard molar energies of combustion, measured by mini-bomb combustion calorimetry. The Knudsen mass-loss effusion technique was used to measure the dependence of the vapour pressure of the crystals with the temperature, thus deriving their standard molar enthalpies of sublimation by means of the Clausius-Clapeyron equation. Combining the standard molar enthalpies of formation and sublimation of the crystalline terphenyls, the standard molar enthalpies of formation in the gaseous state, at T = 298.15 K, were derived for the three isomers. Results are provided in a table. The results show small but detectable isomerization enthalpies between the terphenyls, indicating the following relative enthalpic stabilities: m- > p- ∼ o-terphenyl

Radiographic correlation of dental and skeletal age: Third molar, an age indicator.

Science.gov (United States)

Suma, Gn; Rao, Balaji B; Annigeri, Rajeshwari G; Rao, Dayashankara Jk; Goel, Sumit

2011-01-01

Age estimation plays a great role in forensic investigations, orthodontic and surgical treatment planning, and tooth transplantation. Teeth offer an excellent material for age determination by stages of development below the age of 25 years and by secondary changes after the age of 25 years. Third molar is often not included for this purpose due to its notorious developmental patterns. The aim of this study was to evaluate the development of third molar anlage in relation to skeletal maturities and the chronological age. One hundred and fifty-six young individuals, 78 males and 78 females, were selected. The stages of development of all the third molars in every individual were determined from panoramic radiographs. The skeletal development was assessed using hand wrist radiographs. Data were analyzed statistically for mean value, standard deviation and the relationship between the recorded characteristics. A STRONG CORRELATION WAS FOUND BETWEEN THIRD MOLAR DEVELOPMENT AND SKELETAL MATURITY (IN MALES: r=0.88, Pthird molar and 0.89 for mandibular third molar, Page, developmental stages of third molars and maturation of epiphyses of hand. Any of the three parameters could be used for the assessment of other maturities.

CANINE ECTOPIC TREATMENT WITH FIRST MOLAR EXTRACTION

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Angelica Margo

2015-06-01

Full Text Available Decision to extract or not and the type of tooth must be analyzed carefully in orthodontic treatment. Preferable tooth to be extracted was the tooth with large caries or restoration. Usually the type of tooth to be extracted was second molar (if the third molar appears, incisor, first molar, and combination of several teeth. Orthodontic treatment with molar extraction is more difficult to treat and the result is usually compromise. There are several considerations in extracting first molar such as tooth with large caries or restoration, hypoplasia, periapical disease, large discrepancy, high maxilla-mandibular plane angle, and cases with anterior open bite. Nowadays, orthodontic cases with molar extraction do not prolong the treatment time compared to premolar extraction case, but the anchorage system must be considered carefully. The present case was treated with extraction of first molar to solve anterior crowding with maximum anchorage at the upper jaw and using Nance Holding Appliance.

Association between clinical parameters and the presence of active caries lesions in first permanent molars Associação entre parâmetros clínicos e a presença de lesões ativas de cárie em primeiros molares permanentes

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Juliana Maria Quaglio

2006-12-01

Full Text Available The aim of the present study was to evaluate the association between clinical parameters and the presence of active caries lesions on the occlusal surface of first permanent molars. Forty eight children (5.8-13.8 years-old with at least one first permanent molar present were selected. The clinical parameters evaluated were gender, age, DMF-T and dmf-t, presence of active white spots in other teeth, general plaque index, tooth's dental arch (upper or lower, tooth's side (right or left, presence of visible plaque and eruption degree of the first permanent molars. The first permanent molars were evaluated through visual inspection by two examiners in order to assess the presence of active or inactive caries lesions on the occlusal surface. Univariate and multivariate analyses for determination of the association between clinical parameters and the presence of active caries lesions in these teeth were performed. The presence of active white spots in other teeth was associated with the presence of active caries lesions in the first permanent molars, in both univariate and multivariate analyses (Odds ratio = 8.8 and 1.9, respectively. The presence of abundant visible plaque on the occlusal surface of the first permanent molars (Odds ratio = 3.5 in the univariate analysis, and 3.9 in the multivariate one also presented a significant association. In conclusion, the presence of active white spots in other teeth and the presence of considerable visible plaque were associated with the presence of active caries lesions on the occlusal surfaces of first permanent molars.O objetivo do presente trabalho foi avaliar a associação entre parâmetros clínicos e presença de lesões ativas de cárie sobre a superfície oclusal de primeiros molares permanentes. Quarenta e oito crianças (5,8-13,8 anos com pelo menos um primeiro molar permanente foram selecionadas. Os parâmetros clínicos avaliados foram sexo, idade, CPO-D e ceo-d, presença de manchas brancas

Incisor and molar overjet, arch contraction, and molar relationship in the mixed dentition in repaired complete unilateral cleft lip and palate: A qualitative and quantitative appraisal.

Science.gov (United States)

Disthaporn, Suteeta; Suri, Sunjay; Ross, Bruce; Tompson, Bryan; Baena, Diogenes; Fisher, David; Lou, Wendy

2017-07-01

To compare the mixed dentition incisor and molar overjet, severity of contraction of the dental arch, and the sagittal molar relationship on the cleft side vs the noncleft side in children with repaired complete unilateral cleft of the lip and palate (UCLP). Orthodontic records taken prior to orthodontic preparation for alveolar bone grafting were screened to select study casts from patients with nonsyndromic repaired complete UCLP who did not have mandibular skeletal or dental asymmetry. The study sample comprised dental casts from 74 children aged 8.9 ± 1 years. Standardized digital photographs were acquired at 1:1 magnification. A coordinate system was developed using digital image-processing software (Photoshop CS4 and Adobe Illustrator). Incisor and molar overjet, Angle's classification, and arch contraction were recorded. Descriptive statistics, paired t-tests, and kappa statistics were used to compare the cleft and noncleft sides. A negative overjet of -1 to -5 mm was often present at the incisors, with greater frequency and magnitude on the cleft side. Class II molar relation was more frequent on the cleft side (61.1%) than on the noncleft side (47.2%). Significantly greater contraction of the cleft side deciduous canine and deciduous first molar was noted, while the difference was very minor at the first permanent molar. Cleft side maxillary arch contraction was most severe in the deciduous canine and first deciduous molar region and progressively less severe in the posterior region of the arch. A greater frequency and severity of negative overjet and Class II molar relationship was seen on the cleft side.

Molar Incisiv Hypomineralisasjon - MIH Litteraturstudie

OpenAIRE

Khan, Aisha Farnaz

2017-01-01

Introduksjon: MIH er definert som emaljehypomineralisering av systemisk opprinnelse der 1 til 4 av første permanente molarer er rammet. Incisiver er også ofte affiserte. Hensikten med denne litteraturstudien er å lage en oversikt over, og vurdere tilgjengelig litteratur om MIH, og bruke litteraturen som bakgrunn for å utarbeide en informasjonsbrosjyre om MIH. Materiale og metode: Det ble utført et elektronisk søk i PubMed med søkestrengene ”Molar incisor hypomineralization MIH” og ”Molar inci...

Permanent molars: Delayed development and eruption

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Arathi R

2006-05-01

Full Text Available Delayed development and eruption of all the permanent molars is a rare phenomenon, which can cause disturbance in the developing occlusion. The eruption of permanent first and second molars is very important for the coordination of facial growth and for providing sufficient occlusal support for undisturbed mastication. In the case described, the first permanent molars were delayed in their development and were seen erupting at the age of nine and a half years. Severe disparity between the left and the right side of the dentition with respect to the rate of development of molars were also present.

Micro-computed Tomographic Analysis of Mandibular Second Molars with C-shaped Root Canals.

Science.gov (United States)

Amoroso-Silva, Pablo Andrés; Ordinola-Zapata, Ronald; Duarte, Marco Antonio Hungaro; Gutmann, James L; del Carpio-Perochena, Aldo; Bramante, Clovis Monteiro; de Moraes, Ivaldo Gomes

2015-06-01

The goal of the present study was to evaluate the morphometric aspects of the internal anatomy of the root canal system of mandibular second molars with C-shaped canals. Fifty-two extracted second mandibular molars with C-shaped canals, fused roots, and radicular grooves were selected from a Brazilian population. The samples were scanned with a micro-computed tomographic scanner at a voxel size of 19.6 μm. The root canal cross sections were recorded as C1, C2, C3, and C4 root canal configurations according to the modified Melton classification. Morphometric parameters, including the major and minor diameters of the root canals, the aspect ratio, the roundness, and the tridimensional configuration (merging, symmetric, and asymmetric), were evaluated. The 3-dimensional reconstruction images of the teeth indicated an even distribution within the sample. The analysis of the prevalence of the different cross-sectional configurations of the C-shaped molars revealed that these were predominantly of the C4 and C3 configurations (1 mm from the apex) and the C1 and C2 configurations in the cervical third. According to the morphometric parameters, the C1 and the distal aspect of the C2 configurations exhibited the lowest roundness values and higher values for the area, major diameter, and aspect ratio in the apical third. Mandibular molars with C-shaped root canals exhibited similar distributions of symmetric, asymmetric, and merging type canals. The C1 configuration and the distal aspect of the C2 configuration exhibited the highest area values, low roundness values, and large apical diameters. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Age-related changes in molar topography and shearing crest length in a wild population of mountain Gorillas from Volcanoes National Park, Rwanda.

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Glowacka, Halszka; McFarlin, Shannon C; Catlett, Kierstin K; Mudakikwa, Antoine; Bromage, Timothy G; Cranfield, Michael R; Stoinski, Tara S; Schwartz, Gary T

2016-05-01

Great ape teeth must remain functional over long lifespans. The molars of the most folivorous apes, the mountain gorillas, must maintain shearing function for 40+ years while the animals consume large quantities of mechanically challenging foods. While other folivorous primates experience dental senescence, which compromises their occlusal surfaces and affects their reproductive success as they age, it is unknown whether dental senescence also occurs in mountain gorillas. In this article, we quantified and evaluated how mountain gorilla molars change throughout their long lifespans. We collected high-resolution replicas of M(1)s (n = 15), M(2)s (n = 13), and M(3)s (n = 11) from a cross-sectional sample of wild mountain gorilla skeletons from the Virunga Volcanoes, ranging in age from 4 to 43 years. We employed dental topographic analyses to track how aspects of occlusal slope, angularity, relief index, and orientation patch count rotated change with age. In addition, we measured the relative length of shearing crests in two- and three-dimensions. Occlusal topography was found to decrease, while 2D relative shearing crest length increased, and 3D relative crest lengths were maintained with age. Our findings indicate that shearing function is maintained throughout the long lifetimes of mountain gorillas. Unlike the dental senescence experienced by other folivorous primates, mountain gorillas do not appear to possess senesced molars despite their long lifetimes, mechanically challenging diets, and decreases in occlusal topography with age. © 2016 Wiley Periodicals, Inc.

Clinical and orthopantomographic evaluation of mandibular third molar

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F K Saraswati

2010-01-01

Full Text Available Objective: To evaluate sensitivity of orthopentograph (OPG in assessing the number and morphology of roots of the mandibular third molar. Materials and Methods : The study population consisted of 100 ILTMs (impacted lower third molars ranging from 18 to 42 years with equal sex distribution. All the teeth were subsequently extracted , collected and compared with OPG features for position, numb,er, morphology, and relation to mandibular canal. Conclusion: In conclusion, a large sample study is suggested with techniques like Clark′s and right angle technique which determines the three-dimensional orientation of the impacted teeth.

Variabilidad de las proporciones molares en poblaciones humanas: un abordaje empleando modelos del desarrollo y experimentales / Variability of molar proportions in human populations: insights from developmental models and experiments in mice

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Lucas A. D´Addona

2016-03-01

experimental studies have not yet been integrated in the context of biological anthropology. In this sense, this paper proposes: a to evaluate the consistency between changes in molar proportions in human populations that exhibit a wide variation in tooth size and the predictions derived from an inhibitory cascade model of dental development, and b to analyze the effect of the systemic factors controlling the growth of the organism on the lower molars proportions using strains of Mus musculus. The crown area of the mandibular molars was estimated from the bucco-lingual and mesio-distal diameters. The results obtained for human populations showed that the pattern of variation in molar proportions is consistent with expectations derived from the inhibitory cascade model and that most groups exhibit a general trend towards molar size reduction in the antero-posterior direction. Also, a significant positive association between the total molar area and the molar ratios M2/M1 and M3/M1 was observed. In the experimental models, growth alteration caused by systemic factors (protein subnutrition and reduced growth hormone resulted in a reduction of total molar area associated with changes in molar proportions. The latter are consistent with an increased antero-posterior inhibition. Overall, these results suggest that alterations in the systemic factors that control molar area can produce changes in the proportion of activators and inhibitors, and contribute in turn to inter-population differentiation in molar proportions. Keywords: Inhibitory cascade model; dental size; experimental and comparative approach

The effect of CaO/SiO2 molar ratio of CaO-Al2O3-SiO2 glasses on their structure and reactivity in alkali activated system.

Science.gov (United States)

Kucharczyk, Sylwia; Sitarz, Maciej; Zajac, Maciej; Deja, Jan

2018-04-05

The influence of CaO/SiO 2 molar ratio of calcium aluminosilicate glasses on resulting structure and reactivity was investigated. Chemical compositions of glasses were chosen to mimic the composition of the fly ash and slag amorphous phase. Understanding the reactivity of these materials is of high importance allowing further development of the composite cements to limit the environmental footprint of cement industry. Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy were employed to examine the structure of glasses. Reactivity of the glasses was analyzed on paste samples after 1, 2, 7, 28 and 90days of curing by means of thermogravimetry (TGA), X-ray diffraction (XRD) and FTIR. Spectroscopic results emphasize dependence of the structure on the chemical composition of the glasses. The higher CaO/SiO 2 the more depolymerized the glass network is, though there is no direct correlation with the reactivity. Significant differences in reactivity is observed primarily between the glasses of peraluminous (CaO/Al 2 O 3 1). Amongst the pastes made of glasses of percalcic region a higher degree of reaction at later ages is observed for the paste containing glass of lower CaO/SiO 2 molar ratio. This is due to both degree of depolimerization and the nature of these glasses (pozzolanic and hydraulic materials). No difference of degree of reaction has been observed within the glasses of CaO/SiO 2 lower than 1. Copyright © 2018 Elsevier B.V. All rights reserved.

The effect of CaO/SiO2 molar ratio of CaO-Al2O3-SiO2 glasses on their structure and reactivity in alkali activated system

Science.gov (United States)

Kucharczyk, Sylwia; Sitarz, Maciej; Zajac, Maciej; Deja, Jan

2018-04-01

The influence of CaO/SiO2 molar ratio of calcium aluminosilicate glasses on resulting structure and reactivity was investigated. Chemical compositions of glasses were chosen to mimic the composition of the fly ash and slag amorphous phase. Understanding the reactivity of these materials is of high importance allowing further development of the composite cements to limit the environmental footprint of cement industry. Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy were employed to examine the structure of glasses. Reactivity of the glasses was analyzed on paste samples after 1, 2, 7, 28 and 90 days of curing by means of thermogravimetry (TGA), X-ray diffraction (XRD) and FTIR. Spectroscopic results emphasize dependence of the structure on the chemical composition of the glasses. The higher CaO/SiO2 the more depolymerized the glass network is, though there is no direct correlation with the reactivity. Significant differences in reactivity is observed primarily between the glasses of peraluminous (CaO/Al2O3 1). Amongst the pastes made of glasses of percalcic region a higher degree of reaction at later ages is observed for the paste containing glass of lower CaO/SiO2 molar ratio. This is due to both degree of depolimerization and the nature of these glasses (pozzolanic and hydraulic materials). No difference of degree of reaction has been observed within the glasses of CaO/SiO2 lower than 1.

Onset of molar incisor hypomineralization (MIH).

Science.gov (United States)

Fagrell, Tobias G; Salmon, Phil; Melin, Lisa; Norén, Jörgen G

2013-01-01

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

Partial molar volumes and partial molar adiabatic compressibilities of a short chain perfluorosurfactant: Sodium heptafluorobutyrate in aqueous solutions at different temperatures

Energy Technology Data Exchange (ETDEWEB)

Blanco, Elena [Group of Biophysics and Interfaces, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Ruso, Juan M. [Group of Biophysics and Interfaces, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain)]. E-mail: faruso@usc.es; Prieto, Gerardo [Group of Biophysics and Interfaces, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Sarmiento, Felix [Group of Biophysics and Interfaces, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain)

2005-12-15

Density and ultrasound measurements of sodium heptafluorobutyrate in aqueous solutions at T = (283.15, 288.15, 293.15, 298.15, 303.15, 308.15, 313.15, 318.15, and 323.15) K have been obtained. From these results partial molar volumes and isentropic partial molar adiabatic compressibilities were calculated. Deviations from the Debye-Hueckel limiting law provide evidence for limited association at lower concentrations. The change of the partial molar volume and isentropic partial molar adiabatic compressibility upon aggregation was calculated. Variations of the change of partial molar volumes and isentropic partial molar adiabatic compressibility upon aggregation are discussed in terms of temperature.

Partial molar volumes and partial molar adiabatic compressibilities of a short chain perfluorosurfactant: Sodium heptafluorobutyrate in aqueous solutions at different temperatures

International Nuclear Information System (INIS)

Blanco, Elena; Ruso, Juan M.; Prieto, Gerardo; Sarmiento, Felix

2005-01-01

Density and ultrasound measurements of sodium heptafluorobutyrate in aqueous solutions at T = (283.15, 288.15, 293.15, 298.15, 303.15, 308.15, 313.15, 318.15, and 323.15) K have been obtained. From these results partial molar volumes and isentropic partial molar adiabatic compressibilities were calculated. Deviations from the Debye-Hueckel limiting law provide evidence for limited association at lower concentrations. The change of the partial molar volume and isentropic partial molar adiabatic compressibility upon aggregation was calculated. Variations of the change of partial molar volumes and isentropic partial molar adiabatic compressibility upon aggregation are discussed in terms of temperature

A counter-intuitive approach to calculating non-exchangeable 2H isotopic composition of hair: treating the molar exchange fraction fE as a process-related rather than compound-specific variable

Science.gov (United States)

Landwehr, J.M.; Meier-Augenstein, W.; Kemp, H.F.

2011-01-01

Hair is a keratinous tissue that incorporates hydrogen from material that an animal consumes but it is metabolically inert following synthesis. The stable hydrogen isotope composition of hair has been used in ecological studies to track migrations of mammals as well as for forensic and archaeological purposes to determine the provenance of human remains or the recent geographic life trajectory of living people. Measurement of the total hydrogen isotopic composition of a hair sample yields a composite value comprised of both metabolically informative, non-exchangeable hydrogen and exchangeable hydrogen, with the latter reflecting ambient or sample preparation conditions. Neither of these attributes is directly measurable, and the non-exchangeable hydrogen composition is obtained by estimation using a commonly applied mathematical expression incorporating sample measurements obtained from two distinct equilibration procedures. This commonly used approach treats the fraction of exchangeable hydrogen as a mixing ratio, with a minimal procedural fractionation factor assumed to be close or equal to 1. Instead, we propose to use full molar ratios to derive an expression for the non-exchangeable hydrogen composition explicitly as a function of both the procedural fractionation factor α and the molar hydrogen exchange fraction fE. We apply these derivations in a longitudinal study of a hair sample and demonstrate that the molar hydrogen exchange fraction fE should, like the procedural fractionation factor α, be treated as a process-dependent parameter, i.e. a reaction-specific constant. This is a counter-intuitive notion given that maximum theoretical values for the molar hydrogen exchange fraction fE can be calculated that are arguably protein-type specific and, as such, fE could be regarded as a compound-specific constant. We also make some additional suggestions for future approaches to determine the non-exchangeable hydrogen composition of hair and the use of

Influence of unilateral maxillary first molar extraction treatment on second and third molar inclination in Class II subdivision patients

NARCIS (Netherlands)

Livas, Christos; Pandis, Nikolaos; Booij, Johan Willem; Halazonetis, Demetrios J.; Katsaros, Christos; Ren, Yijin

Objective: To assess the maxillary second molar (M2) and third molar (M3) inclination following orthodontic treatment of Class II subdivision malocclusion with unilateral maxillary first molar (M1) extraction. Materials and Methods: Panoramic radiographs of 21 Class II subdivision adolescents (eight

Formation of copper nanoparticles in mordenite s with variable SiO{sub 2}/Al{sub 2}O{sub 3} molar ratios under redox treatments

Energy Technology Data Exchange (ETDEWEB)

Petranovskii, V.; Avalos, M. [UNAM, Centro de Nanociencias y Nanotecnologia, Km 107 Carretera Tijuana-Ensenada, 22800 Ensenada, Baja California (Mexico); Stoyanov, E. [University of California, Department of Chemistry, Riverside, 92521 California (United States); Gurin, V. [Belarusian State University, Research Institute for Physical Chemical Problems, Minsk 220080 (Belarus); Katada, N. [Tottori University, Department of Chemistry and Biotechnology, Tottori 680-8552 (Japan); Hernandez, M. A. [Benemerita Universidad Autonoma de Puebla, Departamento de Investigacion en Zeolitas, Ciudad Universitaria, Puebla (Mexico); Pestryakov, A. [Tomsk Polytechnic University, Tomsk 634050 (Russian Federation); Chavez R, F.; Zamorano U, R. [IPN, Escuela Superior de Fisica y Matematicas, Departamento de Fisica, Zacatenco, 07738 Mexico D. F. (Mexico); Portillo, R., E-mail: vitalii@cnyn.unam.mx [Benemerita Universidad Autonoma de Puebla, Facultad de Ciencias Quimicas, Ciudad Universitaria, Puebla (Mexico)

2013-05-01

A series of protonated copper-containing mordenite s with different SiO{sub 2}/Al{sub 2}O{sub 3} molar ratios (MR) in the range of 10{<=}MR{<=}206 was prepared by ion exchange in copper nitrate aqueous solution. The electron paramagnetic resonance of hydrated copper Mordenite s series testifies of several Cu{sup 2+} ion sites. Hydrogen reduction of copper ions incorporated into the mordenite s was shown to lead to different reduced copper species including small metallic particles inter alia. The structural properties and acidity of mordenite s were characterized. The optical appearance of the copper particles showed strong but nonmonotonic dependence on the MR value, in line with the variation in acidity of this series of mordenite s. Correlations between mordenite properties and the formation of different reduced copper species are discussed. (Author)

Morphologic study of the maxillary molars. Part II: Internal anatomy.

Science.gov (United States)

Pécora, J D; Woelfel, J B; Sousa Neto, M D; Issa, E P

1992-01-01

The internal anatomy of three hundred and seventy (370) decalcified and cleared human maxillary molars was studied. Seventy-five percent of the first molars, 58% of the second molars and 68% of the third molars studied presented three (3) root canals and 25% of the first molars, 42% of the second molars and 32% of the third molars presented four (4) root canals. The authors observed that the incidence of two root canals in the mesiobuccal root was higher in second maxillary molars than in first maxillary molars.

Pulpectomy procedures in primary molar teeth

OpenAIRE

Hany Mohamed Aly Ahmed

2014-01-01

Premature loss of primary molars can cause a number of undesirable consequences including loss of arch length, insufficient space for erupting premolars and mesial tipping of the permanent molars. Pulpectomy of primary molar teeth is considered as a reasonable treatment approach to ensure either normal shedding or a long-term survival in instances of retention. Despite being a more conservative treatment option than extraction, efficient pulpectomy of bizarre and tortuous root canals encased ...

Prevalence of Impacted Molar Teeth among Saudi Population in Asir Region, Saudi Arabia - A Retrospective Study of 3 Years.

Science.gov (United States)

Syed, Kamran Bokhari; Zaheer, Kamran Bokhari; Ibrahim, Mohammed; Bagi, Mustafa Abdel; Assiri, Mohammed Abdullah

2013-02-01

To report the prevalence of impacted third molars according to the age, gender and type among Saudi population. This retrospective study involved 3800 panoramic radiographs of subjects aged 18 to 45 years who presented to the College of Dentistry, King Khalid University, Abha, Kingdom of Saudi Arabia for oral care during the period from February 2009 to February 2011. Data collected was entered into a spreadsheet (Excel 2000; Microsoft, US) and analyzed using Statistical Package for Social Sciences (SPSS) version 16.0. A total of 713 impacted teeth were identified (18.76%) (p=0.003). The male to female ratio with impacted third molars was 604:109 (5.54:1) and the ratio of patients with impacted teeth was (5:1). Age group 1 (i.e., 20 to 25 years)had the highest prevalence of third molar tooth impaction (64.5%) and this decreased with increasing age. Incidence of tooth impaction is higher in the mandible than in maxilla. Males had a higher incidence of third molar impaction as compared to the females. Highest incidence is found in the age group of 20-25 years. Mesio-angular impaction was the most predominant type. How to cite this article: Syed KB, Kota Z, Ibrahim M, Bagi MA, Assiri MA. "Prevalence of Impacted Molar Teeth among Saudi Population in Asir Region, Saudi Arabia - A Retrospective Study of 3 Years". J Int Oral Health 2013; 5(1):43-47.

Melting relations in the MgO-MgSiO3 system up to 70 GPa

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Ohnishi, Satoka; Kuwayama, Yasuhiro; Inoue, Toru

2017-06-01

Melting experiments in a binary system MgO-MgSiO3 were performed up to 70 GPa using a CO2 laser heated diamond anvil cell. The quenched samples were polished and analyzed by a dualbeam focused ion beam (FIB) and a field emission scanning electron microscope (FE-SEM), respectively. The liquidus phase and the eutectic composition were determined on the basis of textual and chemical analyses of sample cross sections. Our experimental results show that the eutectic composition is the Si/Mg molar ratio of 0.76 at 35 GPa and it decreases with increasing pressure. Above 45 GPa, it becomes relatively constant at about 0.64-0.65 Si/Mg molar ratio. Using our experimental data collected at a wide pressure range up to 70 GPa together with previous experimental data, we have constructed a thermodynamic model of the eutectic composition of the MgO-MgSiO3 system. The eutectic composition extrapolated to the pressure and temperature conditions at the base of the mantle is about 0.64 Si/Mg molar ratio. The modeled eutectic composition is quite consistent with a previous prediction from ab initio calculations (de Koker et al. in Earth Planet Sci Lett 361:58-63, 2013), suggesting that the simple assumption of a non-ideal regular solution model can well describe the melting relation of the MgO-MgSiO3 system at high pressure. Our results show that the liquidus phase changes from MgO-periclase to MgSiO3-bridgmanite at 35 GPa for the simplified pyrolite composition ( 0.7 Si/Mg molar ratio), while MgSiO3-bridgmanite is the liquidus phase at the entire lower mantle conditions for the chondritic composition ( 0.84 Si/Mg molar ratio).

A surface structural model for ferrihydrite I: Sites related to primary charge, molar mass, and mass density

Science.gov (United States)

Hiemstra, Tjisse; Van Riemsdijk, Willem H.

2009-08-01

A multisite surface complexation (MUSIC) model for ferrihydrite (Fh) has been developed. The surface structure and composition of Fh nanoparticles are described in relation to ion binding and surface charge development. The site densities of the various reactive surface groups, the molar mass, the mass density, the specific surface area, and the particle size are quantified. As derived theoretically, molecular mass and mass density of nanoparticles will depend on the types of surface groups and the corresponding site densities and will vary with particle size and surface area because of a relatively large contribution of the surface groups in comparison to the mineral core of nanoparticles. The nano-sized (˜2.6 nm) particles of freshly prepared 2-line Fh as a whole have an increased molar mass of M ˜ 101 ± 2 g/mol Fe, a reduced mass density of ˜3.5 ± 0.1 g/cm 3, both relatively to the mineral core. The specific surface area is ˜650 m 2/g. Six-line Fh (5-6 nm) has a molar mass of M ˜ 94 ± 2 g/mol, a mass density of ˜3.9 ± 0.1 g/cm 3, and a surface area of ˜280 ± 30 m 2/g. Data analysis shows that the mineral core of Fh has an average chemical composition very close to FeOOH with M ˜ 89 g/mol. The mineral core has a mass density around ˜4.15 ± 0.1 g/cm 3, which is between that of feroxyhyte, goethite, and lepidocrocite. These results can be used to constrain structural models for Fh. Singly-coordinated surface groups dominate the surface of ferrihydrite (˜6.0 ± 0.5 nm -2). These groups can be present in two structural configurations. In pairs, the groups either form the edge of a single Fe-octahedron (˜2.5 nm -2) or are present at a single corner (˜3.5 nm -2) of two adjacent Fe octahedra. These configurations can form bidentate surface complexes by edge- and double-corner sharing, respectively, and may therefore respond differently to the binding of ions such as uranyl, carbonate, arsenite, phosphate, and others. The relatively low PZC of

Autogenous transplantation of maxillary and mandibular molars.

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Reich, Peter P

2008-11-01

Autogenous tooth transplantation has been used as a predictable surgical approach to correct malocclusion and replace edentulous areas. This article focuses on the surgical approach and technique for molar transplantation. Thirty-two patients aged between 11 and 25 years underwent 44 autogenous molar transplantations. The procedure involved transplantation of impacted or newly erupted third molars into the extraction sockets of nonrestorable molars and surgical removal and replacement of horizontally impacted molars into their proper vertical alignment. Five basic procedural concepts were applied: 1) atraumatic extraction, avoiding disruption of the root sheath and root buds; 2) apical contouring of bone at the transplantation site and maxillary sinus lift via the Summers osteotome technique, when indicated, for maxillary molars; 3) preparation of a 4-wall bony socket; 4) avoidance of premature occlusal interferences; and 5) stabilization of the tooth with placement of a basket suture. All 32 patients successfully underwent the planned procedure. To date, 2 patients have had localized infection that resulted in loss of the transplant. The remaining 42 transplants remain asymptomatic and functioning, with a mean follow-up period of 19 months. No infection, ankylosis, loss of the transplant, or root resorption has been noted. In addition, endodontic therapy has not been necessary on any transplanted teeth. Autogenous tooth transplantation has been discussed and described in the literature previously, with a primary focus on cuspid and bicuspid transplantation. The molar transplant is infrequently discussed in today's literature, possibly because of the preponderance of titanium dental implants. Autogenous molar transplantation is a viable procedure with low morbidity and excellent functional and esthetic outcomes. This report shows the successful transplantation of 42 of 44 molars in 32 patients with a mean follow-up period of 19 months.

Does fixed retention prevent overeruption of unopposed mandibular second molars in maxillary first molar extraction cases?

NARCIS (Netherlands)

Livas, Christos; Halazonetis, Demetrios J; Booij, Johan W; Katsaros, Christos; Ren, Yijin

2016-01-01

BACKGROUND: The objective of this study was to investigate whether multistranded fixed retainers prevented overeruption of unopposed mandibular second molars in maxillary first molar extraction cases. METHODS: The panoramic radiographs of 65 Class II Division 1 Caucasian Whites (28 females, 37

On the Size Dependence of Molar and Specific Properties of Independent Nano-phases and Those in Contact with Other Phases

Science.gov (United States)

Kaptay, George

2018-05-01

Nano-materials are materials with at least one nano-phase. A nano-phase is a phase with at least one of its dimensions below 100 nm. It is shown here that nano-phases have at least 1% of their atoms along their surface layer. The ratio of surface atoms is proportional to the specific surface area of the phase, defined as the ratio of its surface area to its volume. Each specific/molar property has its bulk value and its surface value for the given phase, being always different, as the energetic states of the atoms in the bulk and in the surface layer of a phase are different. The average specific/molar property of a nano-phase is modeled here as a linear combination of the bulk and surface values of the same property, scaled with the ratio of the surface atoms. That makes the performance of all nano-phases proportional to their specific surface area. As the characteristic size of the nano-phase is inversely proportional to its specific surface area, all specific/molar properties of nano-phases are inversely proportional to the characteristic size of the phase. This is applied to the size dependence of the molar Gibbs energy of the nano-phase, which appears to be in agreement with the thermodynamics of Gibbs. This agreement proves the general validity of the present model on the size dependence of the specific/molar properties of independent nano-phases. It is shown that the properties of nano-phases are different for independent nano-phases (surrounded only by their equilibrium vapor phase) and for nano-phases in multi-phase situations, such as a liquid nano-droplet in the sessile drop configuration.

Molecular representation of molar domain (volume), evolution equations, and linear constitutive relations for volume transport.

Science.gov (United States)

Eu, Byung Chan

2008-09-07

In the traditional theories of irreversible thermodynamics and fluid mechanics, the specific volume and molar volume have been interchangeably used for pure fluids, but in this work we show that they should be distinguished from each other and given distinctive statistical mechanical representations. In this paper, we present a general formula for the statistical mechanical representation of molecular domain (volume or space) by using the Voronoi volume and its mean value that may be regarded as molar domain (volume) and also the statistical mechanical representation of volume flux. By using their statistical mechanical formulas, the evolution equations of volume transport are derived from the generalized Boltzmann equation of fluids. Approximate solutions of the evolution equations of volume transport provides kinetic theory formulas for the molecular domain, the constitutive equations for molar domain (volume) and volume flux, and the dissipation of energy associated with volume transport. Together with the constitutive equation for the mean velocity of the fluid obtained in a previous paper, the evolution equations for volume transport not only shed a fresh light on, and insight into, irreversible phenomena in fluids but also can be applied to study fluid flow problems in a manner hitherto unavailable in fluid dynamics and irreversible thermodynamics. Their roles in the generalized hydrodynamics will be considered in the sequel.

Lingual nerve injury following surgical removal of mandibular third molar

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Abduljaleel Azad Samad

2017-12-01

Full Text Available Background and objective: The close proximity of lingual nerve in relation to the lingual cortical bone of the posterior mandibular third molar is clinically important because lingual nerve may be subjected to trauma during surgical removal of the impacted lower third molar. This prospective study aimed to evaluate the incidence of lingual nerve paresthesia following surgical removal of mandibular third molar in College of Dentistry, Hawler Medical University. Methods: A total of 116 third molars surgery were carried out under local anesthesia for 116 patients for removal of lower mandibular teeth Using Terence Ward's incision made in all cases, and after that, the buccal flap was reflected, lingual tissues had been retracted during bone removal with a periosteal elevator. The sensory disturbance was evaluated on the 7th postoperative day by standard questioning the patients: “Do you have any unusual feeling in your tongue, lingual gingiva and mucosa of the floor of the mouth?" Results: One patient experienced sensory disturbance, the lingual nerve paresthesia incidence was 0.9% as a transient sensory disturbance, while no patient of permanent sensory disturbance. Conclusion: The incidence of injury to the lingual nerve can be minimized by careful clinical evaluation, surgeon’s experience, surgical approach and knowledge about anatomical landmarks during surgical removal of an impacted lower third molar tooth.

Ectopic eruption of the maxillary first permanent molar: characteristics and occurrence in growing children.

Science.gov (United States)

Barberia-Leache, Elena; Suarez-Clúa, María Cruz; Saavedra-Ontiveros, Dolores

2005-07-01

The purpose of this study was to determine the characteristics and occurrence of the ectopic eruption of the maxillary first permanent molar in a sample of growing Spanish children. A descriptive, observational, retrospective study was done using the radiographs of 509 consecutive patients, who were in the first phase of mixed dentition. A method was designed to evaluate the amount of pathologic resorption of the second maxillary primary molar and the impaction of the first permanent molar measured in millimeters. Statistical analysis of the studied variables was done using chi-square, analysis of variance, and Pearson correlation coefficient. The frequency of occurrence was 4.3% with no differences in both sexes. Of these, 36.4% were unilateral and 63.6% bilateral with a right:left relation of 3:1. Of the 36 ectopic molars, 69.4% self-corrected spontaneously. In such cases, the pathological resorption of the root of the second maxillary primary molar and its adverse clinical implications were persistent. The relation between self-correction and impaction was 2.27:1. The average impaction on the right side was 2.91 mm and 1.6 mm on the left side. Correlation between the magnitude of resorption and grade of impaction was not observed. Although resorption was found on grades I and II, spontaneous self-correction could occur without arch length loss. However, on grade III or more, therapeutic intervention has to be done. The benefit of early diagnosis and treatment of the maxillary first permanent molar is the prevention of the premature loss of second maxillary deciduous molar and the resulting malocclusion.

Effect of carbonate and phosphate ratios on the transformation of calcium orthophosphates

Energy Technology Data Exchange (ETDEWEB)

Eliassi, Mohammad Daoud, E-mail: eliassi2007@gmail.com [Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070 (China); Zhao, Wei [State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences, Yangling 712100 (China); Tan, Wen Feng, E-mail: wenfeng.tan@hotmail.com [Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070 (China)

2014-07-01

Graphical abstract: Complexes among phosphate, carbonate and calcium have been prepared via a facile hydrothermal route. The synthesized product at the low (0.15) and the high (1.8) molar ratio of PO{sub 4}{sup 3−}/CO{sub 3}{sup 2−} is calcium phosphate hydrate and hydroxylapatite (HAp), respectively. Molar ratios of PO{sub 4}{sup 3−}/CO{sub 3}{sup 2−} are effective on the reduction of carbonate activity during the crystallization of HAp. - Highlights: • Formation of different complexes from CO{sub 3}{sup 2−}, PO{sub 4}{sup 3−} and Ca{sup 2+} solutions at 60 °C. • Molar ratios of PO{sub 4}{sup 3−}/CO{sub 3}{sup 2} cause changes in phase and size of synthesized products. • Addition of PO{sub 4}{sup 3} inhibited the activity of CO{sub 3}{sup 2−} during bound with Ca{sup 2+}. • The phase transformation was completed, when CO{sub 3}{sup 2−} peaks disappeared in FTIR. • PO{sub 4}{sup 3−}, CO{sub 3}{sup 2−} and Ca{sup 2+} distributed heterogeneously on the surface of precipitation. - Abstract: Complexes among phosphate, carbonate and calcium have been synthesized by a designed hydrothermal method. Effects of carbonate and phosphate ratios on the transformation of calcium-orthophosphates were investigated. With X-ray diffraction measurement the synthesized product at the low (0.15) and the high (1.8) molar ratio of PO{sub 4}{sup 3−}/CO{sub 3}{sup 2−} is calcium phosphate hydrate at pH 9.0, and hydroxylapatite (HAp) at pH 8.0, respectively. Fourier transform infrared spectroscopy of product at the high ratio (1.8) of PO{sub 4}{sup 3−}/CO{sub 3}{sup 2−} shows that the CO{sub 3}{sup 2−} peaks disappear, and the strong peaks at 1412 and 1460 cm{sup −1} are assigned to the vibrations of PO{sub 4}{sup 3−} in HAp. {sup 31}P nuclear magnetic resonance spectra of products at the low (0.15–0.6) to the high (1.2–1.8) ratios of PO{sub 4}{sup 3−}/CO{sub 3}{sup 2−} are obtained at 2.9 and 2.7 ppm, respectively. Molar ratios of PO

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

Science.gov (United States)

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

2012-12-01

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

Autotransplantation of Mandibular Third Molar: A Case Report

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Pabbati Ravi kumar

2012-01-01

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

Survival of sealants in molars affected by molar-incisor hypomineralization: 18-month follow-up

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Camila Maria Bullio FRAGELLI

2017-04-01

Full Text Available Abstract The objective of this study was to evaluate the clinical survival of sealants applied in first permanent molars (FPMs affected by molar-incisor hypomineralization (MIH, at 18 months of follow-up. Forty-one first permanent molars were selected from 21 children, 6–8 years of age. MIH was classified by one calibrated examiner (kappa = 0.80 according to EAPD criteria. The inclusion criteria were fully erupted FPMs with MIH or sound FPMs (without MIH for which sealant treatment was indicated. The FPMs were assigned to two groups: CG (control group and HG (MIH group. Both groups were treated with sealant (FluroShield. Clinical follow-up was performed from baseline to 18 months to assess anatomical form, marginal adaptation, retention and presence of caries, according to criteria set by the United States Public Health Service-Modified, and was conducted by a blinded examiner (kappa = 0.80. The actuarial method was used to evaluate the survival of the sealants. The survival rates for the groups were compared using Fisher’s exact test (α = 5%. The cumulative survival rates were 81% at 1 month, 68.8% at 6 months, 68.8% at 12 months, and 62.6% at 18 months for CG, and 88% at 1 month, 84% at 6 months, 76% at 12 months, and 72% at 18 months for HG. No significant difference was found between the groups. The sealants in molars affected by MIH presented a survival rate similar to the sealants in the control, suggesting that sealants may be an adequate approach for preventing carious lesions in MIH-affected molars.

Managing molar-incisor hypomineralization: A systematic review.

Science.gov (United States)

Elhennawy, Karim; Schwendicke, Falk

2016-12-01

We systematically reviewed treatment modalities for MIH-affected molars and incisors. Trials on humans with ≥1 MIH molar/incisor reporting on various treatments were included. Two authors independently searched and extracted records. Sample-size-weighted annual failure rates were estimated where appropriate. The risk of bias was assessed using the Newcastle-Ottawa scale. Electronic databases (PubMed, Embase, Cochrane CENTRAL, Google Scholar) were screened, and hand searches and cross-referencing performed. Fourteen (mainly observational) studies were included. Ten trials (381 participants) investigated MIH-molars, four (139) MIH-incisors. For molars, remineralization, restorative or extraction therapies had been assessed. For restorative approaches, mean (SD) annual failure rates were highest for fissure sealants (12[6]%) and glass-ionomer restorations (12[2]%), and lowest for indirect restorations (1[3]%), preformed metal crowns (1.3 [2.1]%) and composite restorations (4[3]%). Ony study assessed extraction of molars in young patients (median age 8.2 years), the majority of them without malocclusions, but third molars in development. Spontaneous alignment of second molars was more frequent in the maxilla (55%) than the mandible (47%). For incisors, desensitizing agents successfully managed hypersensitivity. Micro-abrasion and composite veneers improved aesthetics. Few, mainly moderate to high-risk-studies investigated treatment of MIH. Remineralization or sealants seem suitable for MIH-molars with limited severity and/or hypersensitivity. For severe cases, restorations with composites or indirect restorations or preformed metal crowns seem suitable. Prior to tooth extraction as last resort factors like the presence of a general malocclusion, patients' age and the status of neighboring teeth should be considered. No recommendations can be given for MIH-incisors. Dentists need to consider the specific condition of each tooth and the needs and expectations of

Excess molar volume along with viscosity, refractive index and relative permittivity for binary mixtures of exo-tetrahydrodicyclopentadiene with four octane isomers

International Nuclear Information System (INIS)

Yue, Lei; Qin, Xiaomei; Wu, Xi; Xu, Li; Guo, Yongsheng; Fang, Wenjun

2015-01-01

Highlights: • Binary mixtures of JP-10 with octane isomers are studied as model hydrocarbon fuels. • Density, viscosity, refractive index and relative permittivity are determined. • Excess molar volumes and viscosity deviations are calculated and correlated. - Abstract: The fundamental physical properties including density, viscosity, refractive index and relative permittivity, have been measured for binary mixtures of exo-tetrahydrodicyclopentadiene (JP-10) with four octane isomers (n-octane, 3-methylheptane, 2,4-dimethylhexane and 2,2,4-trimethylpentane) over the whole composition range at temperatures T = (293.15 to 313.15) K and pressure p = 0.1 MPa. The values of excess molar volume (V m E ), viscosity deviation (Δη), refractive index deviation (Δn D ) and relative permittivity deviation (Δε r ) are then calculated. All of the values of V m E and Δη are observed to be negative, while those of Δn D and Δε r are close to zero. The effects of temperature and composition on the variation of V m E values are discussed. The negative values of V m E and Δη are conductive to high-density and low-resistance of fuels, which is favorable for the design and preparation of advanced hydrocarbon fuels

A Molar Pregnancy within the Fallopian Tube

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Laura Allen

2016-01-01

Full Text Available Background. Discussion of the incidence of molar pregnancy and ectopic pregnancy. Role of salpingostomy and special considerations for postoperative care. Case. The patient is a 29-year-old G7P4 who presented with vaginal bleeding in the first trimester and was initially thought to have a spontaneous abortion. Ultrasound was performed due to ongoing symptoms and an adnexal mass was noted. She underwent uncomplicated salpingostomy and was later found to have a partial molar ectopic pregnancy. Conclusion. This case illustrates the rare occurrence of a molar ectopic pregnancy. There was no indication of molar pregnancy preoperatively and this case highlights the importance of submitting and reviewing pathological specimens.

Taking advantage of an unerupted third molar: a case report

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Igor Figueiredo Pereira

Full Text Available ABSTRACT Introduction: Treatments with dental surgery seek to displace tooth to the correct position within the dental arch. Objective: To report a clinical case that took advantage of an unerupted third molar. Case history: A male patient, 18 years of age, was referred by his dentist to evaluate the third molars. The clinical exam revealed no visible lower third molars. The computed tomography (CT exam showed the presence of a supernumerary tooth in the region of the mandibular ramus, on the left side, and impaction of the third molar, which was causing root resorption on the second molar, thus making it impossible to remain in the buccal cavity. The preferred option, therefore, was to remove both second molar and the supernumerary tooth, in addition to attaching a device to the third molar during surgery for further traction. Results: After 12 months, the third molar reached the proper position. Conclusion: When a mandibular second permanent molar shows an atypical root resorption, an impacted third molar can effectively substitute the tooth by using an appropriate orthodontic-surgical approach.

[An 18 month evaluation of MM-MTA pulpotomy on primary decayed molars].

Science.gov (United States)

Abou Chedid, J C; Mchayleh, N; Khalil, I; Melki, B; Hardan, L S

2015-12-01

Pulpotomy is the most performed and controversial therapeutic in pediatric dentistry. Formocresol is known to have a toxic effect on living tissues, a mutagenic and carcinogenic potential with a systemic uptake of formocresol via pulpotomized teeth, other alternative products have been investigated. 40 molars were pulpotomized using Micro Mega Mineral Trioxide Aggregate (MM-MTA), which eliminates the need for the use of formocresol. The effects of this material were evaluated both clinically and radiographically. Post-operative control examinations were performed at 1, 6, 12, and 18 months trying to detect spontaneous or stimulated pain, pathological tooth mobility, abscesses or fistulas, internal or external pathological tooth resorption, periapical bone destruction, or canal obliteration. Pain was absent at 18 months post operatively. Thirty six molar treated with the MM-MTA didn't show any mobility or pain, one molar presented a pathological resorption and one molar presented an abscess without a fistula at 12 month. The observations were compared to others related to formocresol, ferric sulfate, MTA, and laser pulpotomies, using the Chi-square test x2. The abundance of positive result strongly demonstrate that the MM-MTA pulpotomy on carious temporary molars is a promising technique.

Prevalence of cheese molars in eleven-year-old Dutch children.

Science.gov (United States)

Weerheijm, K L; Groen, H J; Beentjes, V E; Poorterman, J H

2001-01-01

In the Netherlands, first permanent molars with idiopathic enamel disturbances (IED) are called cheese molars. Though concern is expressed about their prevalence, adequate figures on the subject are missing. The porous enamel of cheese molars can be very sensitive to cold air and can decay rapidly. The aim of the present study was to investigate the prevalence in eleven-year-old Dutch children of cheese molars (IED). During an epidemiological study performed in four cities in the Netherlands, the first permanent molars and central incisors of eleven-year-old children were examined for hypoplasia, opacities, posteruptive enamel loss, premature extraction, and atypical restorations. The observation of a hypoplasia excluded the possibility of cheese molar. A total of 497 children were examined. Six percent (n = 128) of the molars (n = 1988) showed signs of IED (cheese molars), 10 percent of the children had cheese molars of which 8 percent two or more. Incisors (4 percent) with opacities were found in 3 percent in combination with two or more cheese molars. Among the four cities, no significant differences in occurrence were found. The results of this study showed that in 10 percent of the Dutch children eleven years of age, cheese molars (IED) were found. The cause for the phenomenon called cheese molars appears to be child centered. Further studies on prevalence, causes and prevention are mandatory.

Impaction of lower third molars and their association with age: radiological perspectives.

Science.gov (United States)

Ryalat, Soukaina; AlRyalat, Saif Aldeen; Kassob, Zaid; Hassona, Yazan; Al-Shayyab, Mohammad H; Sawair, Faleh

2018-04-04

Third molars are the most commonly impacted teeth, and their extraction is the most commonly performed procedure in oral and maxillofacial surgery. The aim of the present study is to describe the pattern of mandibular third molar impaction and to define the most appropriate age for prophylactic extraction of mandibular third molar teeth. A total of 1198 orthopantomographs (OPGs) with 1810 impacted lower third molars were reviewed by two authors. The pattern of eruption in relation to patient's age was examined using standard radiographic points and angles. Statistical analysis was performed using SPSS for Windows release 16.0 (SPSS Inc., Chicago, IL, USA). In patients older than 20 years, vertical pattern of impaction was the most common (21.4%); while in young patients; horizontal impaction was more common (21.3%). Furthermore, there was a constant pattern of increase in Pell-Gregory ramus class 1 with increasing age, as the prevalence of class 1 was 0% at age 18 years compared to 54.9% at the age of 26 years. Frequency of vertical impaction of lower third molars was seen more at an older age (> 20 years) in this study, with an increase in the retromolar space. Late extraction of mandibular third molar teeth (i.e. after the age of 20) is therefore recommended when prophylactic extraction is considered.

Radiolucency below the crown of mandibular horizontal incompletely impacted third molars and acute inflammation in men with diabetes

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Minoru Yamaoka

2009-05-01

Full Text Available Minoru Yamaoka, Yusuke Ono, Masahide Ishizuka, Kouichi Yasuda, Takashi Uematsu, Kiyofumi FurusawaOral and Maxillofacial Surgery, Matsumoto Dental University, Shiojiri, Nagano 399-0781, JapanAbstract: Although mandibular third molar has a high risk of infection extending any complications, the influence of diabetes on radiolucency and acute inflammation in pericoronitis remains unclear. The present study was to evaluate whether radiolucency below the crown is related to acute inflammation in mandibular horizontal incompletely impacted third molars and to review the records of 140 men more than 45 years with and without diabetes. The odds ratio of exhibiting acute inflammation was 3.38 (95% CI: 1.13–10.16, p < 0.05 and that of exhibiting severe acute inflammation was 15.38 (95% CI: 3.56–66.49, p < 0.0001, indicating an association of acute pericoronitis in diabetes. The frequency of radiolucency below the crown and below the root in diabetics was similar to that in nondiabetics. However, the odds ratio of exhibiting both radiolucency below the crown and acute inflammation under the diabetic condition was 4.85 (95% CI: 1.60–14.73, p < 0.01, whereas that of diabetics showing both radiolucency below the root and acute inflammation was 0.46 (95% CI: 0.06–3.74, p = 0.74. Radiolucency below the crown and acute inflammation were associated with diabetes, but that below root and acute inflammation were not associated with diabetes, indicating that the region below the crown carries susceptibility to acute pericoronitis, whereas the periodontium shows a protective effect against acute pericoronitis.Keywords: radiolucency, acute inflammation, mandible, third molar, diabetes, periodontium

Excess molar volumes and partial molar volumes for (propionitrile + an alkanol) at T = 298.15 K and p = 0.1 MPa

International Nuclear Information System (INIS)

Deenadayalu, N.; Bhujrajh, P.

2006-01-01

The excess molar volumes and the partial molar volumes for (propionitrile + an alkanol) at T = 298.15 K and at atmospheric pressure are reported. The hydrogen bonding between the OH133;NC groups are discussed in terms of the chain length of the alkanol. The alkanols studied are (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 1-pentanol). The excess molar volume data was fitted to the Redlich-Kister equation The partial molar volumes were calculated from the Redlich-Kister coefficients

Time-dependent fracture probability of bilayer, lithium-disilicate-based glass-ceramic molar crowns as a function of core/veneer thickness ratio and load orientation

Science.gov (United States)

Anusavice, Kenneth J.; Jadaan, Osama M.; Esquivel–Upshaw, Josephine

2013-01-01

Recent reports on bilayer ceramic crown prostheses suggest that fractures of the veneering ceramic represent the most common reason for prosthesis failure. Objective The aims of this study were to test the hypotheses that: (1) an increase in core ceramic/veneer ceramic thickness ratio for a crown thickness of 1.6 mm reduces the time-dependent fracture probability (Pf) of bilayer crowns with a lithium-disilicate-based glass-ceramic core, and (2) oblique loading, within the central fossa, increases Pf for 1.6-mm-thick crowns compared with vertical loading. Materials and methods Time-dependent fracture probabilities were calculated for 1.6-mm-thick, veneered lithium-disilicate-based glass-ceramic molar crowns as a function of core/veneer thickness ratio and load orientation in the central fossa area. Time-dependent fracture probability analyses were computed by CARES/Life software and finite element analysis, using dynamic fatigue strength data for monolithic discs of a lithium-disilicate glass-ceramic core (Empress 2), and ceramic veneer (Empress 2 Veneer Ceramic). Results Predicted fracture probabilities (Pf) for centrally-loaded 1,6-mm-thick bilayer crowns over periods of 1, 5, and 10 years are 1.2%, 2.7%, and 3.5%, respectively, for a core/veneer thickness ratio of 1.0 (0.8 mm/0.8 mm), and 2.5%, 5.1%, and 7.0%, respectively, for a core/veneer thickness ratio of 0.33 (0.4 mm/1.2 mm). Conclusion CARES/Life results support the proposed crown design and load orientation hypotheses. Significance The application of dynamic fatigue data, finite element stress analysis, and CARES/Life analysis represent an optimal approach to optimize fixed dental prosthesis designs produced from dental ceramics and to predict time-dependent fracture probabilities of ceramic-based fixed dental prostheses that can minimize the risk for clinical failures. PMID:24060349

Time-dependent fracture probability of bilayer, lithium-disilicate-based, glass-ceramic, molar crowns as a function of core/veneer thickness ratio and load orientation.

Science.gov (United States)

Anusavice, Kenneth J; Jadaan, Osama M; Esquivel-Upshaw, Josephine F

2013-11-01

Recent reports on bilayer ceramic crown prostheses suggest that fractures of the veneering ceramic represent the most common reason for prosthesis failure. The aims of this study were to test the hypotheses that: (1) an increase in core ceramic/veneer ceramic thickness ratio for a crown thickness of 1.6mm reduces the time-dependent fracture probability (Pf) of bilayer crowns with a lithium-disilicate-based glass-ceramic core, and (2) oblique loading, within the central fossa, increases Pf for 1.6-mm-thick crowns compared with vertical loading. Time-dependent fracture probabilities were calculated for 1.6-mm-thick, veneered lithium-disilicate-based glass-ceramic molar crowns as a function of core/veneer thickness ratio and load orientation in the central fossa area. Time-dependent fracture probability analyses were computed by CARES/Life software and finite element analysis, using dynamic fatigue strength data for monolithic discs of a lithium-disilicate glass-ceramic core (Empress 2), and ceramic veneer (Empress 2 Veneer Ceramic). Predicted fracture probabilities (Pf) for centrally loaded 1.6-mm-thick bilayer crowns over periods of 1, 5, and 10 years are 1.2%, 2.7%, and 3.5%, respectively, for a core/veneer thickness ratio of 1.0 (0.8mm/0.8mm), and 2.5%, 5.1%, and 7.0%, respectively, for a core/veneer thickness ratio of 0.33 (0.4mm/1.2mm). CARES/Life results support the proposed crown design and load orientation hypotheses. The application of dynamic fatigue data, finite element stress analysis, and CARES/Life analysis represent an optimal approach to optimize fixed dental prosthesis designs produced from dental ceramics and to predict time-dependent fracture probabilities of ceramic-based fixed dental prostheses that can minimize the risk for clinical failures. Copyright © 2013 Academy of Dental Materials. All rights reserved.

External and internal anatomy of third molars.

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Guerisoli, D M; de Souza, R A; de Sousa Neto, M D; Silva, R G; Pécora, J D

1998-01-01

The external and internal anatomy of 269 third molars (155 maxillary and 114 mandibular) were studied. The teeth were measured, classified according to their root number and shape and the internal anatomy was observed by the use of diaphanization. A great anatomical variability was found, with the presence of up to 5 roots in maxillary third molars and 3 roots in mandibular third molars. The number of root canals followed the same pattern.

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

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Hunjan, Jagtar Singh; Eu, Byung Chan

2010-04-07

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

[Orthodontic Management of the Impacted Mandibular Second Molar Tooth].

Science.gov (United States)

Mah, Michael; Takada, Kenji

2016-09-01

When the mandibular permanent second molar becomes impacted, it is identified as a malocclusion that needs treatment as it often leads to unwanted complications such as caries and periodontitis of the adjacent permanent first molar. Other less common complications include root resorption of the adjacent first molar root or continued root development to be in close proximity to the inferior dental alveolar nerve. This paper seeks to differentiate various levels of severity of impaction and review treatment options that are considered clinically available for the proper management of the impacted mandibular permanent second molar. Treatment options that will be discussed in this article include timing of second molar removal for replacement by the third molar, relief of impaction via second premolar removal, surgical repositioning and the combination of third molar removal, surgical exposure and orthodontic uprighting of the impacted tooth. Depending on the severity of the impaction, most impactions can be easily and predictably corrected with nickel titanium archwires or auxillary open coil springs or uprighting springs. Uncommonly, the mandibular permanent second molar can become severely impacted and in close proximity to the inferior dentoalveolar nerve. In these instances, the use of temporary anchorage devices such as microimplants has shown to be successful in uprighting the severely impacted mandibular permanent second molars. © EDP Sciences, SFODF, 2016.

Epidemiological Status of Third Molars in an Iranian Population

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Mahnaz Sheikhi

2016-07-01

Full Text Available Background Impaction of third molars is a common phenomenon. The incidence of impacted third molars varies in different populations. Objectives The aim of this study is to assess radiographic status (root development degree, angulation, and eruption level of the third molar in Iranian population via panoramic radiographs. Patients and Methods 647 patients, ranging in age from 17 - 25, were selected from three regions of Iran. Based on their panoramic radiographs, their root development degree, angulation, and eruption levels were analyzed. Results The angulation of upper third molars were vertical (44.6%, distoangular (44.1%, mesioangular (10.7%, and horizontal (0.6%. For lower third molars, the angulation was mesioangular (44.5%, vertical (33.8%, distoangular (12.2%, and horizontal (9.5%. The eruption levels of maxillary third molars were C > A> B, and for mandibular third molars they were A > B> C. The order of root development prevalence of the maxillary and mandibular third molars was complete > 2/3 > 1/3. Conclusions The most common status of impaction of the third molars in the maxilla was vertical angulation, level C of eruption, and complete root formation. In the mandible it was mesioangular, level A of eruption, and complete root formation. Since the study sample consists of patients from the north, middle, and south of Iran, the sample can represent the whole population of Iran.

One year Survival Rate of Ketac Molar versus Vitro Molar for Occlusoproximal ART Restorations: a RCT

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PACHECO Anna Luisa de Brito

2017-11-01

Full Text Available Abstract Good survival rates for single-surface Atraumatic Restorative Treatment (ART restorations have been reported, while multi-surface ART restorations have not shown similar results. The aim of this study was to evaluate the survival rate of occluso-proximal ART restorations using two different filling materials: Ketac Molar EasyMix (3M ESPE and Vitro Molar (DFL. A total of 117 primary molars with occluso-proximal caries lesions were selected in 4 to 8 years old children in Barueri city, Brazil. Only one tooth was selected per child. The subjetcs were randomly allocated in two groups according to the filling material. All treatments were performed following the ART premises and all restorations were evaluated after 2, 6 and 12 months. Restoration survival was evaluated using Kaplan-Meier survival analysis and Log-rank test, while Cox regression analysis was used for testing association with clinical factors (α = 5%. There was no difference in survival rate between the materials tested, (HR = 1.60, CI = 0.98–2.62, p = 0.058. The overall survival rate of restorations was 42.74% and the survival rate per group was Ketac Molar = 50,8% and Vitro Molar G2 = 34.5%. Cox regression test showed no association between the analyzed clinical variables and the success of the restorations. After 12 months evaluation, no difference in the survival rate of ART occluso-proximal restorations was found between tested materials.

Treatment of Ectopic Mandibular Second Permanent Molar with Elastic Separators

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R. Rajesh

2014-01-01

Full Text Available 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.

Mandibular molar crown-topography, a biological predisposing ...

African Journals Online (AJOL)

Mandibular molar crown-topography, a biological predisposing factor to development of caries – a post-mortem analysis of 2500 extracted lower permanent molars at the dental centre, University of Benin teaching hospital.

Acrylamide and 5-hydroxymethylfurfural formation during biscuit baking. Part II: Effect of the ratio of reducing sugars and asparagine.

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Nguyen, Ha T; van der Fels-Klerx, H J Ine; van Boekel, M A J S

2017-09-01

This study investigated acrylamide and 5-hydroxymethylfurfural (HMF) formation during biscuit baking. Four types of wheat flour with different molar ratios of total fructose and glucose to asparagine were investigated. Nevertheless, the molar ratio in all four biscuit doughs exceeded one after proofing due to enzyme action. Data obtained after baking were used to develop a mechanistic model, based on the asparagine-related pathway, for acrylamide and HMF formation in the four baked biscuit types. Asparagine reacted with fructose to form a Schiff base before decarboxylation to produce acrylamide without Amadori rearrangement product and sugar fragmentation. Fructose contributed considerably to acrylamide formation and to HMF formation via caramelization in all four biscuit types. No clear correlation was found between acrylamide and HMF in baked biscuits, nor between asparagine and the sum of glucose and fructose concentrations in the wheat flour. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of third molar surgery on oral health-related quality of life in the first postoperative week using Dutch version of oral health impact profile-14

NARCIS (Netherlands)

van Wijk, A.; Kieffer, J.M.; Lindeboom, J.H.

2009-01-01

Purpose: The present study investigated the effect of third molar surgery on oral health-related quality of life, related to pain and clinical variables, in the first postoperative week using the Dutch version of the 14-item Oral Health Impact Profile. Materials and Methods: A total of 50 patients,

Predicting pathology in impacted mandibular third molars

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Aveek Mukherji

2017-01-01

Full Text Available Introduction: The rising incidence of the impacted mandibular third molars and their association with pathologies is now considered a public health problem. Aims and Objectives: The objective of this study was to assess the position of impacted mandibular third molars that are prone to developing pathologies and to determine the frequency and type of pathological conditions associated with these impacted teeth to facilitate planning for their prophylactic removal. Materials and Methods: Consecutive panoramic radiographs and clinical examination of 300 patients with impacted mandibular third molars were collected. They were segregated according to Pell and Gregory’s classification, Winter’s classification, and according to their state of eruption. These were correlated with associated pathologies based on clinical and radiological criteria. Statistical Analysis Used: Descriptive statistics included computation of percentages, mean, and standard deviations. The statistical test applied for the analysis was Pearson’s Chi-square test (χ2. For this test, confidence interval and P value were set at 93% and ≤0.03, respectively. Results: The pathology most commonly associated with impacted third molars was pericoronitis, which had the highest frequency of occurrence in partially erupted, distoangular, and IA positioned (as per Pell and Gregory classification impacted teeth. Impacted mandibular third molars, which were in IA position, placed mesially, and partially erupted, were prone to develop pathologies such as dental caries and periodontitis. Conclusion: The clinical and radiographical features of impacted third molar may be correlated to the development of their pathological complications. The partially impacted mandibular third molars with mesioangularly aligned in IA position have the highest potential to cause pathological complications.

Bilateral lower second molar impaction in teenagers: An emergent problem?

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Shinohara Elio

2010-01-01

Full Text Available The frequency of simultaneously impacted second and third molars in teenagers is increasing and becoming a common occurrence in adolescent oral surgery practice. The traditional treatment is the removal of the third molar by conventional access but repositioning of the surgical flap to the distal face of the first molar can predispose to complications such as pericoronitis and delayed healing of the attached gingiva. We present a case in which we use the germectomy approach to remove the impacted third molar for the eruption of the second molar through a vestibular incision. This incision offers excellent bone exposure and exit route for the third molar without disturbing the gingiva attached architecture on the distal face of the first molar providing good healing environment.

Antagonistic Growth Effects of Mercury and Selenium in Caenorhabditis elegans Are Chemical-Species-Dependent and Do Not Depend on Internal Hg/Se Ratios.

Science.gov (United States)

Wyatt, Lauren H; Diringer, Sarah E; Rogers, Laura A; Hsu-Kim, Heileen; Pan, William K; Meyer, Joel N

2016-03-15

The relationship between mercury (Hg) and selenium (Se) toxicity is complex, with coexposure reported to reduce, increase, and have no effect on toxicity. Different interactions may be related to chemical compound, but this has not been systematically examined. Our goal was to assess the interactive effects between the two elements on growth in the nematode Caenorhabditis elegans, focusing on inorganic and organic Hg (HgCl2 and MeHgCl) and Se (selenomethionine, sodium selenite, and sodium selenate) compounds. We utilized aqueous Hg/Se dosing molar ratios that were either above, below, or equal to 1 and measured the internal nematode total Hg and Se concentrations for the highest concentrations of each Se compound. Observed interactions were complicated, differed between Se and Hg compounds, and included greater-than-additive, additive, and less-than-additive growth impacts. Biologically significant interactions were only observed when the dosing Se solution concentration was 100-25,000 times greater than the dosing Hg concentration. Mitigation of growth impacts was not predictable on the basis of internal Hg/Se molar ratio; improved growth was observed at some internal Hg/Se molar ratios both above and below 1. These findings suggest that future assessments of the Hg and Se relationship should incorporate chemical compound into the evaluation.

Comparison of Articaine and Lidocaine for Buccal Infiltration After Inferior Alveolar Nerve Block For Intraoperative Pain Control During Impacted Mandibular Third Molar Surgery.

Science.gov (United States)

da Silva-Junior, Geraldo Prisco; de Almeida Souza, Liane Maciel; Groppo, Francisco Carlos

In order to compare the efficacy of lidocaine and articaine for pain control during third molar surgery, 160 patients presenting bilateral asymptomatic impacted mandibular third molars were selected. They received 1.8 mL of 2% lidocaine with epinephrine 1:100,000 during inferior alveolar nerve block. In group 1 (n = 80), an infiltrative injection of 0.9 mL of 2% lidocaine with epinephrine 1:100,000 was performed in buccal-distal mucosa of the third molar. Group 2 (n = 80) received 0.9 mL of 4% articaine with epinephrine 1:100,000 in the contralateral side. All procedures were performed at the same visit, by a single operator, in a double-blind and parallel design. The duration of each surgery and the moment when the patient expressed pain were noted. Data were analyzed by nonpaired t test and chi-square test (alpha = 5%). Duration of surgery did not differ (p = .83) between Groups 1 (19.8 ± 2.3 minutes) and 2 (19.7 ± 3.0 minutes). Pain was expressed more in group 1 (26.3%) than in group 2 (10%) (odds ratio = 3.2, p = .0138). In both groups, tooth sectioning was the most painful event (p inferior alveolar nerve block in controlling intraoperative pain related to impacted mandibular third molar surgery.

Effect of third molar surgery on oral health-related quality of life in the first postoperative week using Dutch version of Oral Health Impact Profile-14

NARCIS (Netherlands)

van Wijk, Arjen; Kieffer, Jacobien M.; Lindeboom, Jerome H.

2009-01-01

The present study investigated the effect of third molar surgery on oral health-related quality of life, related to pain and clinical variables, in the first postoperative week using the Dutch version of the 14-item Oral Health Impact Profile. A total of 50 patients, referred to the Department of

Reimbursement rates and policies for primary molar pit-and-fissure sealants across state Medicaid programs.

Science.gov (United States)

Chi, Donald L; Singh, Jennifer

2013-11-01

Little is known about Medicaid policies regarding reimbursement for placement of sealants on primary molars. The authors identified Medicaid programs that reimbursed dentists for placing primary molar sealants and hypothesized that these programs had higher reimbursement rates than did state programs that did not reimburse for primary molar sealants. The authors obtained Medicaid reimbursement data from online fee schedules and determined whether each state Medicaid program reimbursed for primary molar sealants (no or yes). The outcome measure was the reimbursement rate for permanent tooth sealants (calculated in 2012 U.S. dollars). The authors compared mean reimbursement rates by using the t test (α = .05). Seventeen Medicaid programs reimbursed dentists for placing primary molar sealants (34 percent), and the mean reimbursement rate was $27.57 (range, $16.00 [Maine] to $49.68 [Alaska]). All 50 programs reimbursed dentists for placement of sealants on permanent teeth. The mean reimbursement for permanent tooth sealants was significantly higher in programs that reimbursed for primary molar sealants than in programs that did not ($28.51 and $23.67, respectively; P = .03). Most state Medicaid programs do not reimburse dentists for placing sealants on primary molars, but programs that do so have significantly higher reimbursement rates. Medicaid reimbursement rates are related to dentists' participation in Medicaid and children's dental care use. Reimbursement for placement of sealants on primary molars is a proxy for Medicaid program generosity.

Determination of partial molar volumes from free energy perturbation theory†

Science.gov (United States)

Vilseck, Jonah Z.; Tirado-Rives, Julian

2016-01-01

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

Determination of partial molar volumes from free energy perturbation theory.

Science.gov (United States)

Vilseck, Jonah Z; Tirado-Rives, Julian; Jorgensen, William L

2015-04-07

Partial molar volume is an important thermodynamic property that gives insights into molecular size and intermolecular interactions in solution. Theoretical frameworks for determining the partial molar volume (V°) of a solvated molecule generally apply Scaled Particle Theory or Kirkwood-Buff theory. With the current abilities to perform long molecular dynamics and Monte Carlo simulations, more direct methods are gaining popularity, such as computing V° directly as the difference in computed volume from two simulations, one with a solute present and another without. Thermodynamically, V° can also be determined as the pressure derivative of the free energy of solvation in the limit of infinite dilution. Both approaches are considered herein with the use of free energy perturbation (FEP) calculations to compute the necessary free energies of solvation at elevated pressures. Absolute and relative partial molar volumes are computed for benzene and benzene derivatives using the OPLS-AA force field. The mean unsigned error for all molecules is 2.8 cm(3) mol(-1). The present methodology should find use in many contexts such as the development and testing of force fields for use in computer simulations of organic and biomolecular systems, as a complement to related experimental studies, and to develop a deeper understanding of solute-solvent interactions.

Evaluation of the anatomical alterations of lower molars mesial root?s apical third

OpenAIRE

FRÖNER Izabel Cristina; IMPERADOR Cristina Aparecida; SOUZA Luiz Gustavo de

1999-01-01

The anatomical apex of the mesial root of the lower molars presents a morphological complexity related to the number and shape of the root canals as well as of the apical foramen and isthmus presence. The knowledge of the complexity of the endodontic system of the molar root area is essencial to select more carefully the best instrumentation and obturation technique, to obtain a more successful endodontic therapy.

Evaluation of the anatomical alterations of lower molars mesial root?s apical third

Directory of Open Access Journals (Sweden)

FRÖNER Izabel Cristina

1999-01-01

Full Text Available The anatomical apex of the mesial root of the lower molars presents a morphological complexity related to the number and shape of the root canals as well as of the apical foramen and isthmus presence. The knowledge of the complexity of the endodontic system of the molar root area is essencial to select more carefully the best instrumentation and obturation technique, to obtain a more successful endodontic therapy.

Evaluation of skeletal and dental age using third molar calcification, condylar height and length of the mandibular body.

Science.gov (United States)

Kedarisetty, Sunil Gupta; Rao, Guttikonda Venkateswara; Rayapudi, Naveen; Korlepara, Rajani

2015-01-01

To identify the most reliable method for age estimation among three variables, that is, condylar height, length of mandibular body and third molar calcification by Demirjian's method. Orthopantomograms and lateral cephalograms of 60 patients with equal gender ratio were included in the study, among each gender 15 subjects were below 18 years and 15 subjects were above 18 years. Lateral cephalograms were traced, height of condyle and mandibular body are measured manually on the tracing paper, OPG's were observed on radiographic illuminator and maturity score of third molar calcification was noted according to Demirjian's method. All the measurements were subjected to statistical analysis. The results obtained are of no significant difference between estimated age and actual age with all three parameters (P > 0.9780 condylar height, P > 0.9515 length of mandibular body, P > 0.8611 third molar calcification). Among these three, length of mandibular body shows least standard error test (i.e. 0.188). Although all three parameters can be used for age estimation, length of mandibular body is more reliable followed by height of condyle and third molar calcification.

Influence of the Ti concentration and of the Ti:Mo molar ratio, in the efficiency of the 99 Mo - 99m Tc generator, at basis of gels of titanium molybdates

International Nuclear Information System (INIS)

Cortes R, O.; Monroy G, F.; Martinez C, T.

2003-01-01

The 99m Tc, continues being the radionuclide more used in nuclear medicine to world scale. The production of this radioisotope, is carried out by means of generators 99 Mo/ 99m Tc that get ready commercially with 99 Mo of high specific activity, adsorbed in alumina (2 mg 99 Mo/g alumina) and that they are elutriated every 23 hours. In an alternative way, it is intended to use gels of titanium molybdates, as matrices of this generators. The gels are synthesized starting from solutions of ammonium molybdates and of titanium tetrachloride in aqueous media. These gels allow to incorporate until 25% of molybdenum in their structure, being been able to use 99 Mo of low specific activity that can be obtained starting from the reaction 98 Mo (n, γ) 99 Mo. With the object of producing generators of medium activity, with the base of gels of titanium molybdates, intends in this work, to study the influence of two synthesis parameters of these gels: the concentration of the titanium solutions and the molar ratio Ti: Mo. The decrease of the concentration of the titanium solution, used during the synthesis of the gels, is converted in an efficiency decrease and radionuclide purity of the generators, as well as an increment so much of the volume of elutriation, as of the pH of the elutriates. The gels that contain an major number of titanium moles, regarding the molybdenum moles, present a greater radionuclide purity, but they diminish their efficiency. The best characteristics for the gels synthesis of titanium molybdates are: a molar ratio 1:1 for Ti and Mo, and to use solutions of titanium whose concentration is near at 1 M. (Author)

PULPOTOMIES WITH PORTLAND CEMENT IN HUMAN PRIMARY MOLARS

Science.gov (United States)

Conti, Taísa Regina; Sakai, Vivien Thiemy; Fornetti, Ana Paula Camolese; Moretti, Ana Beatriz Silveira; Oliveira, Thais Marchini; Lourenço, Natalino; Machado, Maria Aparecida Andrade Moreira; Abdo, Ruy Cesar Camargo

2009-01-01

Two clinical cases in which Portland cement (PC) was applied as a medicament after pulpotomy of mandibular primary molars in children are presented. Pulpotomy using PC was carried out in two mandibular first molars and one mandibular second molar, which were further followed-up. At the 3, 6 and 12-month follow-up appointments, clinical and radiographic examinations of the pulpotomized teeth and their periradicular area revealed that the treatments were successful in maintaining the teeth asymptomatic and preserving pulpal vitality. Additionally, the formation of a dentin bridge immediately below the PC could be observed in the three molars treated. PC may be considered as an effective alternative for primary molar pulpotomies, at least in a short-term period. Randomized clinical trials with human teeth are required in order to determine the suitability of PC before unlimited clinical use can be recommended. PMID:19148409

Variable permanent mandibular first molar: Review of literature

Science.gov (United States)

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

2013-01-01

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

Internal structure of mandible around mandibular molar using computed tomography. Anatomical consideration of molar anchorage in orthodontic treatment

International Nuclear Information System (INIS)

Enomoto, Yutaka; Yamashita, Daisuke; Saito, Katsuhiko; Kasai, Kazutaka

2008-01-01

For establishment of fine occlusion, facial profile and oral function in orthodontic treatment, molar anchorage in teeth movement is important manner in extracted cases. The aims of this study were to investigate the relationship between facial morphology and internal structure of mandibular body in molar region by computer tomography, and to discuss about molar anchorage in orthodontic treatment. The data for this study were obtained from 35 modern male Japanese skulls (mean age; 27 year-old, ranged from 18 year-old to 47 year-old). Measurement variables were FMA, SN to mandibular plane angle, gonial angle, alveolar breadth, cortical bone thickness of buccal and lingual sides, and the distance between dental root and cortical bone. As a result, alveolar breadth and the distance between dental root and cortical bone were narrow in long facial type, on the contrary, these variables were wide in short facial type. The result suggested that these variables were considered important factors as molar anchorage in extracted cases. (author)

Loss of the First Permanent Molar: Risk Factors and Adolescent Oral Health

OpenAIRE

Daraí Bárbara Sánchez Montero; Yahima Pons López; Ana Ibis Betancourt García; Anilec Santateresa Marchante

2017-01-01

Foundation: the replacement of the primary dentition begins with the eruption of the first permanent molars that will be subjected to various risk factors.Objective: to determine the existing relation between the first permanent molar loss and the risk factors in adolescents from 12 to 14 years old. Method: a cross descriptive study was developed between October 20011 and March 2012. On a universe of 560 students, a simple random sampling was done and a sample of 185 patients was selected. On...

Prevalence, association, and sexual dimorphism of Carabelli's molar and shovel incisor traits amongst Jordanian population.

Science.gov (United States)

Khraisat, A; Taha, Sahar T; Jung, R E; Hattar, S; Smadi, L; Al-Omari, I K; Jarbawi, M

2007-09-01

The correlation between dental morphological traits can be used as an indicator to show major ethnic differences. Therefore, this study investigated the prevalence of Carabelli's molar and shovel incisor traits and tested their association and sexual dimorphism in Jordanian population. Three hundred subjects of school children at their 10th grade and of 15.5-year as an average age were involved. Alginate impressions for the maxillary arch were taken, poured, and casts were then trimmed. The selected accurate casts were of 132 male- and 155 female-students. The examined morphologic traits were Carabelli's trait on the maxillary first and second molars and shovel-shaped incisors. The relationship between different traits was investigated by Nonparametric Correlation analysis and Independent Sample t test was used to test sexual dimorphism in trait expression. The prevalence of Carabelli's trait in maxillary first molar and shovel trait in maxillary central incisor was relatively high (65.0 % and 53.0 %, respectively). The prevalence of Carabelli's trait on maxillary second molars was 3.8 %. Nonparametric Correlations revealed a strongest positive correlation between Carabelli's trait on maxillary first molar and shovel trait in males (P = 0.005). Significant sexual dimorphism was only found in the prevalence of Carabelli's trait on maxillary first molar (P = 0.013) and shovel trait (P = 0.038). The Jordanian Population had comparatively high prevalence of Carabelli's molar and shovel incisor traits. There was a positive association between Carabelli's trait on maxillary first molar and shovel trait in males. Sexual dimorphism was evident in Carabelli's trait on maxillary first molar and shovel trait.

A New Anatomically Based Nomenclature for the Roots and Root Canals—Part 1: Maxillary Molars

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Jojo Kottoor

2012-01-01

Full Text Available Numerous terminologies have been employed in the dental literature to describe the roots and root canal systems of maxillary molars. This multiplicity in naming of roots and canals makes the reader susceptible to misinterpretation and confusion. No consensus thus far has been arrived at for defining the names of roots and root canals in maxillary molars, including their various morphological aberrations. The anatomical relation of roots and their root canals were identified and were subsequently named based on definite sets of criteria. A new method for identification and naming of roots and root canal anatomy in maxillary molars, based on their root and canal relationship, was formulated and is presented in this paper. The nomenclature makes certain essential modifications to the traditional approach to accommodate naming of the various aberrations presented in the maxillary molars. A simple, yet extensive, nomenclature system has been proposed that appropriately names the internal and external morphology of maxillary molars.

A new anatomically based nomenclature for the roots and root canals-part 1: maxillary molars.

Science.gov (United States)

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

2012-01-01

Numerous terminologies have been employed in the dental literature to describe the roots and root canal systems of maxillary molars. This multiplicity in naming of roots and canals makes the reader susceptible to misinterpretation and confusion. No consensus thus far has been arrived at for defining the names of roots and root canals in maxillary molars, including their various morphological aberrations. The anatomical relation of roots and their root canals were identified and were subsequently named based on definite sets of criteria. A new method for identification and naming of roots and root canal anatomy in maxillary molars, based on their root and canal relationship, was formulated and is presented in this paper. The nomenclature makes certain essential modifications to the traditional approach to accommodate naming of the various aberrations presented in the maxillary molars. A simple, yet extensive, nomenclature system has been proposed that appropriately names the internal and external morphology of maxillary molars.

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

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Kupczik, Kornelius; Hublin, Jean-Jacques

2010-11-01

Neanderthals have a distinctive suite of dental features, including large anterior crown and root dimensions and molars with enlarged pulp cavities. Yet, there is little known about variation in molar root morphology in Neanderthals and other recent and fossil members of Homo. Here, we provide the first comprehensive metric analysis of permanent mandibular molar root morphology in Middle and Late Pleistocene Homo neanderthalensis, and Late Pleistocene (Aterian) and recent Homo sapiens. We specifically address the question of whether root form can be used to distinguish between these groups and assess whether any variation in root form can be related to differences in tooth function. We apply a microtomographic imaging approach to visualise and quantify the external and internal dental morphologies of both isolated molars and molars embedded in the mandible (n=127). Univariate and multivariate analyses reveal both similarities (root length and pulp volume) and differences (occurrence of pyramidal roots and dental tissue volume proportion) in molar root morphology among penecontemporaneous Neanderthals and Aterian H. sapiens. In contrast, the molars of recent H. sapiens are markedly smaller than both Pleistocene H. sapiens and Neanderthals, but share with the former the dentine volume reduction and a smaller root-to-crown volume compared with Neanderthals. Furthermore, we found the first molar to have the largest average root surface area in recent H. sapiens and Neanderthals, although in the latter the difference between M(1) and M(2) is small. In contrast, Aterian H. sapiens root surface areas peak at M(2). Since root surface area is linked to masticatory function, this suggests a distinct occlusal loading regime in Neanderthals compared with both recent and Pleistocene H. sapiens. Copyright © 2010 Elsevier Ltd. All rights reserved.

Fast fission ratio and relative conversion ratio measurements in gadolinium poisoned water moderated UO2 lattices

International Nuclear Information System (INIS)

Murphy, M.F.

1984-01-01

A programme of criticality experiments has been carried out for BNFL by the Battelle reactor facility at Pacific Northwest Laboratories in Washington State, USA. A series of water moderated lattices of 4.3% enriched, 12.7 mm diameter, UO 2 fuel rods was studied, the fuel pitch was varied and the effects of gadolinium poison were measured. This report deals with the measurement of Fast Fission Ratios and Relative Conversion Ratios at the centre of five of the critical lattices. The Fast Fission Ratio (FFR) is defined here as the ratio of the fission rate per atom of U238, to the fission rate per atom of U235. The Relative Conversion Ratio (RCR) is defined as the ratio of the capture rate per ,atom of U238, to the fission rate per atom of U235, in the reactor fuel, relative to the corresponding ratio in a well thermalised neutron spectrum. A major aspect of these measurements was that the packs of foils were prepared at AEEW Winfrith, despatched to the USA for irradiation and returned to Winfrith for counting. This resulted in a considerable logistics problem but by good planning and the co-operation and diligence of all concerned this problem was overcome. However, the long distance involved inevitably meant that samples were not available for measurement until about 28 hours after the irradiation. It was therefore necessary to modify the techniques that are normally used in the Reactor Physics Division Counting Laboratory, where samples are normally available about two hours after shut-down. The techniques used and the results obtained are given below

Cl/Br ratios and chlorine isotope evidences for groundwater salinization and its impact on groundwater arsenic, fluoride and iodine enrichment in the Datong basin, China.

Science.gov (United States)

Li, Junxia; Wang, Yanxin; Xie, Xianjun

2016-02-15

In order to identify the salinization processes and its impact on arsenic, fluoride and iodine enrichment in groundwater, hydrogeochemical and environmental isotope studies have been conducted on groundwater from the Datong basin, China. The total dissolved solid (TDS) concentrations in groundwater ranged from 451 to 8250 mg/L, and 41% of all samples were identified as moderately saline groundwater with TDS of 3000-10,000 mg/L. The results of groundwater Cl concentrations, Cl/Br molar ratio and Cl isotope composition suggest that three processes including water-rock interaction, surface saline soil flushing, and evapotranspiration result in the groundwater salinization in the study area. The relatively higher Cl/Br molar ratio in groundwater from multiple screening wells indicates the contribution of halite dissolution from saline soil flushed by vertical infiltration to the groundwater salinization. However, the results of groundwater Cl/Br molar ratio model indicate that the effect of saline soil flushing practice is limited to account for the observed salinity variation in groundwater. The plots of groundwater Cl vs. Cl/Br molar ratio, and Cl vs δ(37)Cl perform the dominant effects of evapotranspiration on groundwater salinization. Inverse geochemical modeling results show that evapotranspiration may cause approximately 66% loss of shallow groundwater to account for the observed hydrochemical pattern. Due to the redox condition fluctuation induced by irrigation activities and evapotranspiration, groundwater salinization processes have negative effects on groundwater arsenic enrichment. For groundwater iodine and fluoride enrichment, evapotranspiration partly accounts for their elevation in slightly saline water. However, too strong evapotranspiration would restrict groundwater fluoride concentration due to the limitation of fluorite solubility. Copyright © 2015. Published by Elsevier B.V.

Modelling Chemical Kinetics of Soybean Oil Transesterification Process for Biodiesel Production: An Analysis of Molar Ratio between Alcohol and Soybean Oil Temperature Changes on the Process Conversion Rate

Directory of Open Access Journals (Sweden)

Maicon Tait

2006-12-01

Full Text Available A mathematical model describing chemical kinetics of transesterification of soybean oil for biodiesel production has been developed. The model is based on the reverse mechanism of transesterification reactions and describes dynamics concentration changes of triglycerides, diglycerides, monoglycerides, biodiesel, and glycerol production. Reaction rate constants were written in the Arrhenius form. An analysis of key process variables such as temperature and molar ratio soybean oil- alcohol using response surface analysis was performed to achieve the maximum soybean conversion rate to biodiesel. The predictive power of the developed model was checked for the very wide range of operational conditions and parameters values by fitting different experimental results for homogeneous catalytic and non-catalytic processes published in the literature. A very good correlation between model simulations and experimental data was observed.

Piezoelectric Versus Conventional Rotary Techniques for Impacted Third Molar Extraction

Science.gov (United States)

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

2015-01-01

Abstract Impacted third molars are frequently encountered in clinical work. Surgical removal of impacted third molars is often required to prevent clinical symptoms. Traditional rotary cutting instruments are potentially injurious, and piezosurgery, as a new osteotomy technique, has been introduced in oral and maxillofacial surgery. No consistent conclusion has been reached regarding whether this new technique is associated with fewer or less severe postoperative sequelae after third molar extraction. The aim of this study was to compare piezosurgery with rotary osteotomy techniques, with regard to surgery time and the severity of postoperative sequelae, including pain, swelling, and trismus. We conducted a systematic literature search in the Cochrane Library, PubMed, Embase, and Google Scholar. The eligibility criteria of this study included the following: the patients were clearly diagnosed as having impacted mandibular third molars; the patients underwent piezosurgery osteotomy, and in the control group rotary osteotomy techniques, for removing impacted third molars; the outcomes of interest include surgery time, trismus, swelling or pain; the studies are randomized controlled trials. We used random-effects models to calculate the difference in the outcomes, and the corresponding 95% confidence interval. We calculated the weighted mean difference if the trials used the same measurement, and a standardized mean difference if otherwise. A total of seven studies met the eligibility criteria and were included in our analysis. Compared with rotary osteotomy, patients undergoing piezosurgery experienced longer surgery time (mean difference 4.13 minutes, 95% confidence interval 2.75–5.52, P piezosurgery groups. The number of included randomized controlled trials and the sample size of each trial were relatively small, double blinding was not possible, and cost analysis was unavailable due to a lack of data. Our meta-analysis indicates that although patients

Three-dimensional morphology of first molars in relation to ethnicity and the occurrence of cleft lip and palate.

Science.gov (United States)

Echtermeyer, Sandra; Metelmann, Philine H; Hemprich, Alexander; Dannhauer, Karl-Heinz; Krey, Karl-Friedrich

2017-01-01

This study aims to describe morphological peculiarities of maxillary and mandibular first molars in Europeans, Asians and Europeans with cleft lip and palate. Reflex microscopy was used to obtain three-dimensional morphometric landmarks from 40 models (11 Europeans and 13 Asians without cleft lip and palate, 16 Europeans with unilateral cleft lip and palate). The cases were examined using traditional morphometry and geometric morphometry, and visualized using thin-plate splines. Classic morphometry showed no right/left differences in the study groups and no significant differences with regard to the cleft side in patients with cleft lip and palate. In Asians, a significantly greater mesiodistal width was found. Geometric morphometry showed an enlarged centroid size in Asians (maxilla and mandible). In cleft patients, the cleft site did not appear to impact the morphology of first molars. Unilateral clefting did not affect the size and shape of molars; however, characteristic ethnicity-based differences were in fact identified. The results are relevant for orthodontic treatment with preadjusted appliances, and prosthetic CAD/CAM restorations.

Unusual facial pain secondary to inferior alveolar nerve compression caused by impacted mandibular second molar

Directory of Open Access Journals (Sweden)

Urvashi Sharma

2014-01-01

Full Text Available Symptoms of inferior alveolar nerve (IAN compression are reported during endodontic procedures, placement of implants, third molar surgeries, inferior alveolar nerve block injections, trauma, orthognathic injuries, ablative surgeries or use of medicaments. Presented is a rare case of a 15-year-old girl who reported severe pain in relation to an impacted permanent mandibular left second molar, the roots of which had entrapped the mandibular canal causing compression of IAN. Timely surgical intervention and sectional removal of the impacted molar is indicated to relieve the symptoms and avoid permanent damage to the nerve.

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

Science.gov (United States)

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

2012-11-01

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

Molar Incisor Hypomineralisation

NARCIS (Netherlands)

Elfrink, M.; Weerheijm, K.L.

2013-01-01

Molar Incisor Hypomineralisation (mih) wordt omschreven als een hypomineralisatie (van systemische oorsprong) van één tot vier blijvende eerste molaren, vaak in combinatie met aangedane incisieven. mih-molaren zijn fragieler en cariësgevoeliger dan gewone molaren. Een kenmerk van mih-molaren is een

Molar Incisor Hypomineralisation

NARCIS (Netherlands)

Elfrink, M.; Weerheijm, K.L.

2009-01-01

Molar Incisor Hypomineralisation (MIH) wordt gedefinieerd als een hypomineralisatie van systemische oorsprong van één tot vier blijvende eerste molaren, vaak in combinatie met aangedane incisieven. MIH-molaren zijn fragieler en cariësgevoeliger dan gewone molaren. Een kenmerk van MIH-molaren is een

Molar Incisor Hypomineralisation

NARCIS (Netherlands)

Elfrink, M.; Weerheijm, K.

2011-01-01

Molar Incisor Hypomineralisation (mih ) wordt gedefinieerd als een hypomineralisatie van systemische oorsprong van één tot vier blijvende eerste molaren, vaak in combinatie met aangedane incisieven. mih -molaren zijn fragieler en cariësgevoeliger dan gewone molaren. Een kenmerk van mih -molaren is

The not-so-harmless maxillary primary first molar extraction.

Science.gov (United States)

Northway, W M

2000-12-01

Premature loss of primary molars has been associated with space loss and eruptive difficulties, especially when the loss occurs to the primary second molars and when it occurs early. This has not been thought to be the case for primary first molars. The author revisited 13 cases from an earlier study on the effects of premature loss of maxillary primary molars. These longitudinal cases were scrutinized, using serial panoramic radiographs, to explain the irregular response in terms of dental migration. The author presents two case reports. In the earlier study, the author used digitized study casts and the concept of D + E space--the space occupied by the primary first and second molars--to describe the dental migration that occurred after premature tooth loss. Using analysis of variance on data generated using an instrument capable of measuring in tenths of millimeters, the author produced findings regarding the amount of space loss, rate of space loss, effect of age at loss, amount of space regained at the time of replacement by the permanent tooth and effect on Angle's classification. Finally, the author created a simulation describing directional change; this revealed that the maxillary primary first molar loss resulted in a mesial displacement of the permanent canine during eruption. When the maxillary primary first molar is lost prematurely, the first premolar erupts in a more mesial direction than normal, as a result of the mesial incline of the primary second molar, and consumes the space of the permanent canine, which becomes blocked out. Rather than use a space maintainer after the premature loss of the maxillary primary first molar, the author suggests, clinicians can choose from a number of other options for preventing the first premolar from erupting too far in a mesial direction.

Liquid phase PVTx properties of (water + tert-butanol) binary mixtures at temperatures from 278.15 to 323.15 K and pressures from 0.1 to 100 MPa. II. Molar isothermal compressions, molar isobaric expansions, molar thermal pressure coefficients, and internal pressure

International Nuclear Information System (INIS)

Egorov, Gennadiy I.; Makarov, Dmitriy M.; Kolker, Arkadiy M.

2013-01-01

Highlights: ► Molar isothermal compressions and molar isobaric expansions were evaluated. ► Coefficients of thermal pressure and internal pressure were obtained. ► Concentration dependences of coefficients under study display extremes. ► Temperature and pressure dependences of internal pressure of the mixture were linear. -- Abstract: Molar isothermal compressions, molar isobaric expansions, molar coefficients of thermal pressure, and internal pressure were calculated over the whole concentration range of {water (1) + tert-butanol (2)} mixture at pressures from 0.1 to 100 MPa and temperatures from 278.15 to 323.15 K. It was revealed that the extremes, observed on concentration dependences of molar isothermal compression K T,m and molar isobaric expansion E P,m of the mixture, became more pronounced with pressure growth and temperature lowering. Values of molar thermal pressure coefficients of the mixture sharply rose at compositions with small TBA mole fraction and then decreased practically linearly with the alcohol content increasing. Temperature and pressure dependences of the mixture internal pressure were almost linear, and at low TBA concentrations changed significantly from the dependences of water, tert-butanol and their mixtures at large alcohol content

EQUATION OF STATE IN FORM WHICH RELATES MOL FRACTION AND MOLARITY OF TWO (OR MORE COMPONENT THERMODYNAMIC SYSTEM CONSISTED OF IDEAL GASES, AND IT'S APPLICATIONS

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Marko Popović

2010-01-01

Full Text Available Most people would face a problem if there is a need to calculate the mole fraction of a substance A in a gaseous solution (a thermodynamic system containing two or more ideal gases knowing its molarity at a given temperature and pressure. For most it would take a lot of time and calculations to find the answer, especially because the quantities of other substances in the system aren't given. An even greater problem arises when we try to understand how special relativity affects gaseous systems, especially solutions and systems in equilibrium. In this paper formulas are suggested that greatly shorten the process of conversion from molarity to mole fraction and give us a better insight into the relativistic effects on a gaseous system.

Exploring the possibility to store the mixed oxygen-hydrogen cluster in clathrate hydrate in molar ratio 1:2 (O2+2H2).

Science.gov (United States)

Qin, Yan; Du, Qi-Shi; Xie, Neng-Zhong; Li, Jian-Xiu; Huang, Ri-Bo

2017-05-01

An interesting possibility is explored: storing the mixture of oxygen and hydrogen in clathrate hydrate in molar ratio 1:2. The interaction energies between oxygen, hydrogen, and clathrate hydrate are calculated using high level quantum chemical methods. The useful conclusion points from this study are summarized as follows. (1) The interaction energies of oxygen-hydrogen mixed cluster are larger than the energies of pure hydrogen molecular cluster. (2) The affinity of oxygen molecules with water molecules is larger than that of the hydrogen molecules with water molecules. (3) The dimension of O 2 -2H 2 interaction structure is smaller than the dimension of CO 2 -2H 2 interaction structure. (4) The escaping energy of oxygen molecules from the hydrate cell is larger than that of the hydrogen molecules. (5) The high affinity of the oxygen molecules with both the water molecules and the hydrogen molecules may promote the stability of oxygen-hydrogen mixture in the clathrate hydrate. Therefore it is possible to store the mixed (O 2 +2H 2 ) cluster in clathrate hydrate. Copyright © 2017 Elsevier Inc. All rights reserved.

Human age estimation combining third molar and skeletal development.

Science.gov (United States)

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

2012-03-01

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

Standard molar enthalpy of formation of methoxyacetophenone isomers

International Nuclear Information System (INIS)

Amaral, Luísa M.P.F.; Morais, Victor M.F.; Ribeiro da Silva, Manuel A.V.

2014-01-01

Highlights: • Experimental and computational energetic study of methoxyacetophenone isomers. • Enthalpies of formation and phase transition determined by calorimetric techniques. • Quantum chemical calculations allowed estimation of enthalpies of formation. • Structure and energy correlations were established. - Abstract: Values of the standard (p o = 0.1 MPa) molar enthalpy of formation of 2′-, 3′- and 4′-methoxyacetophenones were derived from their standard molar energy of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The Calvet high temperature vacuum sublimation technique was used to measure the enthalpies of sublimation/vaporization of the compounds studied. The standard molar enthalpies of formation of the three compounds, in the gaseous phase, at T = 298.15 K, have been derived from the corresponding standard molar enthalpies of formation in the condensed phase and the standard molar enthalpies for the phase transition. The results obtained are −(232.0 ± 2.5), −(237.7 ± 2.7) and −(241.1 ± 2.1) kJ · mol −1 for 2′-, 3′- and 4′-methoxyacetophenone, respectively. Standard molar enthalpies of formation were also estimated from different methodologies: the Cox scheme as well as two different computational approaches using density functional theory-based B3LYP and the multilevel G3 methodologies

Lower first permanent molars: developing better predictors of spontaneous space closure.

Science.gov (United States)

Teo, Terry Kuo-Yih; Ashley, Paul Francis; Derrick, Donald

2016-02-01

First, first permanent molars (FPMs) of poor prognosis are often planned for extraction at an 'ideal time' so that second permanent molars (SPMs) erupt favourably to replace them. However for lower FPM extractions, timing is not an accurate predictor of success. The aim of this study was to identify additional radiographic factors that could better predict the degree of spontaneous space closure of the lower SPM following FPM extraction. Data from a previous study of 127 lower SPMs from 66 patients was re-analysed by incorporating additional radiographic factors. These included calcification stage of the bifurcation of the SPM, position of the second premolar, mesial angulation of SPM in relation to the FPM, and presence of the third permanent molar. Results were analysed using ordered logistic regression. Only 58 per cent of FPMs extracted at the 'ideal time' (SPM development at Demirjian stage E) had complete space closure. The best outcomes resulted from a combination of SPMs not at Demirjian development stage G, together with the presence of mesial angulation of the SPM and presence of the third permanent molar, where 85 per cent of those cases had complete space closure. Apart from extraction timing of the FPM, consideration must also be given to the presence of the third permanent molar and angulation of the SPM in order to ensure a reliable degree of spontaneous space closure of the lower SPM. © The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Angulation change of the third molar tooth in orthodontic treatment

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Ardiansyah S. Pawinru

2017-04-01

Full Text Available Objective : Impaction of the third molar tooth mandibular is often found in patients with orthodontic treatment. In orthodontic treatment, extraction cases of impaction of the third molar tooth are usually performed, but the patients often refuse this extraction. Extraction of premolar has a good effect on the third molar mandibular angulation during treatment. Material and Methods : This study is a retrospective clinical study with descriptive analytic to find out the effect of the first mandibular premolar tooth extraction to angulation change of the third molar mandibular in orthodontic treatment with a standard edgewise method. Angulation change was performed by comparing the third molar mandibular angulation before and after orthodontic treatment with panoramic radiographs. Angulation of the third molar tooth mandibular was calculated from the angle formed between the long axis of the tooth with the reference line infraorbita. Results : The sample comprised 60 of impacted mandibular third molar region of the left and right regions of 30 patients who had been treated declared cured in clinic of orthodontic specialist of Dentistry Faculty Padjadjaran University. The sample was divided into three (3 groups of patients before treatment angulation of the third molar tooth mandibular under 300, 300 to 600 and above 60o, then measured change of angulation and observed whether it increased, fixed or decreased. Results were analyzed by T- test and Wilcoxon test showed that there was a significant change in angulation of the third molar mandibular in orthodontic treatment with the first premolar tooth mandibular extraction. Conclusion : This study is that the first premolar tooth mandibular extraction affects the angulation of the third molar tooth mandibular after orthodontic treatment.

Anatomical study of the relationship of impacted mandibular third molar root apex to inferior alveolar canal in Kurdistan population using orthopantomogram

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Fedil Andraws Yalda

2017-12-01

Full Text Available Background and objective: Extraction of an impacted mandibular third lower molar tooth is one of the common surgical procedures that may lead to the damage of inferior alveolar nerve due to roots proximity to the mandibular canal. This study aimed to know the relative relationship and proximity of the mandibular third molar roots to the inferior alveolar canal in relation to gender, age, depth of impaction, relation with ramus, and type of angulation of the impacted tooth in Kurdistan population. Methods: A sample of 366 digital panoramic radiographs of patients with impacted mandibular third molar was studied. Panoramic radiographic signs images were evaluated for the presence of root contact with the superior border of the mandibular canal, darkening of the roots apex, deflected roots, narrow root, superimposition of the canal, interruption of the white line, diversion of the inferior alveolar canal, and narrowing of the inferior alveolar canal. The depths of impaction, relation with ramus, and type of angulation were also studied. Results: Significant relation of the proximity of the mandibular third molar roots to the inferior alveolar canal with the gender (P = 0.001 and age (P <0.001 were seen. A significant relation of the proximity of the mandibular third molar roots to the inferior alveolar canal with the depth of impaction (P <0.001, relation with the ramus (P =0.004, and angulation of impaction were also seen (P <0.001. Conclusion: Significant relation of the proximity of the mandibular third molar roots to the inferior alveolar canal with gender, age, depth of impaction, relation with the ramus, and angulation of impaction were seen.

Rare occurrence of the left maxillary horizontal third molar impaction ...

African Journals Online (AJOL)

Rare occurrence of the left maxillary horizontal third molar impaction, the right maxillary third molar vertical impaction and the left mandibular third molar vertical impaction with inferior alveolar nerve proximity in a 30 year old female: a case report.

Bone metabolism in obesity: changes related to severe overweight and dietary weight reduction

DEFF Research Database (Denmark)

Hyldstrup, Lars; Andersen, T; McNair, P

1993-01-01

very-low-calorie diet. Before treatment the bone mineral content of the distal forearm was increased compared to normals (51.9 U vs. 43.7 U, p ..., the bone mineral content had declined by 3.3%. Serum alkaline phosphatase remained unchanged (187.8 U/l vs 186.9 U/l, NS) but serum osteocalcin demonstrated a significant rise (3.94 nmol/l vs 10.53 nmol/l, p ... 25.2 molar ratio x 10(-3), p mineral content was seen. The hydroxyproline/creatinine ratio did still increase (from 25.8 molar ratio x 10(-3) to 30.1 molar ratio x 10(-3), p

The contemporary management of third molars.

Science.gov (United States)

Hyam, D M

2018-03-01

The management of third molars requires a significant assessment and decision process both for the patient and the clinician. The clinician must always identify the indication for third molar surgery, assess the risks of the proposed procedure, and then modify their plan to account for the patient's current and future health, their social and financial setting, and the patient's tolerance of risk. In doing this, the clinician can tailor a solution to meet the individual patient's needs. This decision to remove a third molar is made in the fluid setting of the patient's quality of life and requires regular review. This article gives the clinician the tools, the matrix, and the confidence to guide patients through this process, and outlines some of the pitfalls and common points of bias within the process. © 2018 Australian Dental Association.

Assessment of the relationship between the mandibular third molar and the mandibular canal using panoramic radiograph and cone beam computed tomography

International Nuclear Information System (INIS)

Jung, Yun Hoa; Nah, Kyung Soo; Cho, Bong Hae

2008-01-01

The purpose of this study is to evaluate the position of the mandibular canal in relation to the mandibular third molar by cone beam CT in cases showing a close relationship between the third molar and the mandibular canal on the panoramic radiograph. The panoramic images and cone beam CT scans of 87 impacted mandibular third molars in 60 patients were evaluated to assess the tooth relationship to the mandibular canal. The clearness of the canal wall and the vertical depth of the lower third molar were evaluated on panoramic radiographs. The lower third molars were assessed using cone beam CT to determine the proximity and position of the canal relative to the roots. In the 66 cases where the canal wall was unclear on the panoramic radiographs, 58 (87.9%) of the third molars had contact between the canal and root; 34 (51.5%) canals were showed an inferior position and 22 (33.3%) showed a linguoinferior position on cone beam CT. Interruption of the canal wall on panoramic radiographs was highly predictive of contact between the mandibular canal and the third molar. Cross sectional CT may be indicated for localization of the mandibular canal in such cases.

Developmental constraints revealed by co-variation within and among molar rows in two murine rodents.

Science.gov (United States)

Renaud, Sabrina; Pantalacci, Sophie; Quéré, Jean-Pierre; Laudet, Vincent; Auffray, Jean-Christophe

2009-01-01

Morphological integration corresponds to interdependency between characters that can arise from several causes. Proximal causes of integration include that different phenotypic features may share common genetic sets and/or interact during their development. Ultimate causes may be the prolonged effect of selection favoring integration of functionally interacting characters, achieved by the molding of these proximal causes. Strong and direct interactions among successive teeth of a molar row are predicted by genetic and developmental evidences. Functional constraints related to occlusion, however, should have selected more strongly for a morphological integration of occluding teeth and a corresponding evolution of the underlying developmental and genetic pathways. To investigate how these predictions match the patterns of phenotypic integration, we studied the co-variation among the six molars of the murine molar row, focusing on two populations of house mice (Mus musculus domesticus) and wood mice (Apodemus sylvaticus). The size and shape of the three upper and lower molars were quantified and compared. Our results evidenced similar patterns in both species, size being more integrated than shape among all the teeth, and both size and shape co-varying strongly between adjacent teeth, but also between occluding teeth. Strong co-variation within each molar row is in agreement with developmental models showing a cascade influence of the first molar on the subsequent molars. In contrast, the strong co-variation between molars of the occluding tooth rows confirms that functional constraints molded patterns of integration and probably the underlying developmental pathways despite the low level of direct developmental interactions occurring among molar rows. These patterns of co-variation are furthermore conserved between the house mouse and the wood mouse that diverged >10 Ma, suggesting that they may constitute long-running constraints to the diversification of the murine

Prevalence of missing and impacted third molars in adults aged 25 years and above

Energy Technology Data Exchange (ETDEWEB)

Jung, Yun Hoa; Cho, Bong Hae [Dept. of Oral and Maxillofacial Radiology, School of Dentistry, Pusan National University, Yansan (Korea, Republic of)

2013-12-15

The purpose of this study was to determine the prevalence of missing and impacted third molars in people aged 25 years and above. The study sample of 3,799 patients was chosen randomly from patients who visited Pusan National University Dental Hospital and had panoramic radiographs taken. The data collected included presence and impaction state, angulation, and depth of impaction of third molars, and radiographically detected lesions of third molars and adjacent second molars. A greater percentage of men than women retained at least one third molar. The incidence of third molars decreased with increasing age. The incidence of partially impacted third molars greatly declined after the age of 30. Vertically impacted maxillary third molars and horizontally impacted mandibular third molars were most frequent in all age groups. Among the maxillary third molars, those impacted below the cervical line of the second molar were most frequent in all age groups, and among the mandibular third molars, deeply impacted third molars were most frequent in those aged over 40. Dental caries was the most common radiographic lesion of the third molars. Mesioangularly impacted third molars showed radiographic lesions in 13 (9.5%) adjacent maxillary second molars and 117 (27.4%) mandibular second molars. The number of remaining third molars decreased and the percentage of Class C depth increased with age. Caries was the most frequent lesion in third molars. Partially impacted mesioangular third molars showed a high incidence of caries or periodontal bone loss of the adjacent second molar. Regular oral examination will be essential to keep asymptomatic third molars in good health.

Prevalence of missing and impacted third molars in adults aged 25 years and above

International Nuclear Information System (INIS)

Jung, Yun Hoa; Cho, Bong Hae

2013-01-01

The purpose of this study was to determine the prevalence of missing and impacted third molars in people aged 25 years and above. The study sample of 3,799 patients was chosen randomly from patients who visited Pusan National University Dental Hospital and had panoramic radiographs taken. The data collected included presence and impaction state, angulation, and depth of impaction of third molars, and radiographically detected lesions of third molars and adjacent second molars. A greater percentage of men than women retained at least one third molar. The incidence of third molars decreased with increasing age. The incidence of partially impacted third molars greatly declined after the age of 30. Vertically impacted maxillary third molars and horizontally impacted mandibular third molars were most frequent in all age groups. Among the maxillary third molars, those impacted below the cervical line of the second molar were most frequent in all age groups, and among the mandibular third molars, deeply impacted third molars were most frequent in those aged over 40. Dental caries was the most common radiographic lesion of the third molars. Mesioangularly impacted third molars showed radiographic lesions in 13 (9.5%) adjacent maxillary second molars and 117 (27.4%) mandibular second molars. The number of remaining third molars decreased and the percentage of Class C depth increased with age. Caries was the most frequent lesion in third molars. Partially impacted mesioangular third molars showed a high incidence of caries or periodontal bone loss of the adjacent second molar. Regular oral examination will be essential to keep asymptomatic third molars in good health.

Cuartos molares supernumerarios: relato de caso clínico

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Daniela Nascimento Silva

2006-04-01

Full Text Available Los dientes supernumerarios se diagnostican mediante exámenes radiográficos de rutina, pues generalmente son asintomáticos. Los cuartos molares representan el segundo grupo de dientes supernumerarios con más frecuencias; ocurren en posición distal a los terceros molares, especialmente en el maxilar superior, y en la mayoría de casos, estos están incluidos. El objetivo de este artículo es realizar la presentación de un caso, de una mujer de 30 anos con los cuartos molares incluidos en el maxilar inferior y describir la técnica para su remoción.Supernumerary teeth are generally asymptomatic and are diagnosed by routine X-ray tests. The fourth molar teeth represent the second group of the most frequent supernumerary teeth, occur in distal position to the third molar teeth, specially in the superior maxilla and, in most of the cases, they are included. The aim of this paper is to comment on the case of a 30-year-old woman with the fourth molar teeth included in the inferior maxilla and to describe the technique used for their removal.

Impacted third molar transplantation on the malpracticed extraction socket.

Science.gov (United States)

Kim, Soung Min; Amponsah, Emmanuel K

2017-12-01

Autotransplantation with or without endodontic therapy is regarded as an alternative treatment option for the replacement of missing teeth. A primary responsibility of a maxillofacial surgeon is to reverse any malpractice to promote successful outcomes and improve the patient's quality of life. This paper presents a malpractice case of incorrect extraction of the lower second molar instead of the impacted third molar. A simple technique of transplanting the impacted third molar to the site of the extracted second molar is introduced by a maxillofacial specialist in Ghana. By making an intentional root socket and fixation without using additional appliances, a novel second molar was achieved with complete recovery. This patient was followed after transplant for a four-year period with the best satisfaction. A grant of the Korean Health Technology R&D Project, Ministry of Health & Welfare, Republic of Korea. (HI15C0689).

Autotransplantation of Mandibular Third Molar with Buccal Cortical Plate to Replace Vertically Fractured Mandibular Second Molar: A Novel Technique.

Science.gov (United States)

Zufía, Juan; Abella, Francesc; Trebol, Ivan; Gómez-Meda, Ramón

2017-09-01

Tooth replacement often leads to inadequate vertical volume in the recipient site bone when a tooth has been extracted because of a vertical root fracture (VRF). This case report presents the autotransplantation of a mandibular third molar (tooth #32) with the attached buccal cortical plate to replace a mandibular second molar (tooth #31) diagnosed with a VRF. After extraction of tooth #31, the recipient socket was prepared based on the size measured in advance with cone-beam computed tomographic imaging. The precise and calculated osteotomy of the cortical bone of tooth #32 allowed for the exact placement of the donor tooth in the position of tooth #31. The total extraoral time was only 25 minutes. The block was fixed to the recipient socket with an osteosynthesis screw and splinted with a double resin wire for 8 weeks. At the 6-month follow-up, the screw was removed, and the stability of the tooth and the regeneration obtained throughout the vestibular area were confirmed. At the 2-year follow-up, the transplanted tooth was asymptomatic and maintained a normal bone level. Advantages of autotransplantation over dental implants include maintenance of proprioception, possible orthodontic movements, and a relatively low cost. This case report demonstrates that an autotransplantation of a third molar attached to its buccal cortical plate is a viable option to replace teeth with a VRF. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Prevalence of missing and impacted third molars in adults aged 25 years and above

Science.gov (United States)

Jung, Yun-Hoa

2013-01-01

Purpose The purpose of this study was to determine the prevalence of missing and impacted third molars in people aged 25 years and above. Materials and Methods The study sample of 3,799 patients was chosen randomly from patients who visited Pusan National University Dental Hospital and had panoramic radiographs taken. The data collected included presence and impaction state, angulation, and depth of impaction of third molars, and radiographically detected lesions of third molars and adjacent second molars. Results A greater percentage of men than women retained at least one third molar. The incidence of third molars decreased with increasing age. The incidence of partially impacted third molars greatly declined after the age of 30. Vertically impacted maxillary third molars and horizontally impacted mandibular third molars were most frequent in all age groups. Among the maxillary third molars, those impacted below the cervical line of the second molar were most frequent in all age groups, and among the mandibular third molars, deeply impacted third molars were most frequent in those aged over 40. Dental caries was the most common radiographic lesion of the third molars. Mesioangularly impacted third molars showed radiographic lesions in 13 (9.5%) adjacent maxillary second molars and 117 (27.4%) mandibular second molars. Conclusion The number of remaining third molars decreased and the percentage of Class C depth increased with age. Caries was the most frequent lesion in third molars. Partially impacted mesioangular third molars showed a high incidence of caries or periodontal bone loss of the adjacent second molar. Regular oral examination will be essential to keep asymptomatic third molars in good health. PMID:24380060

Pattern of third molar impaction in a Saudi population

Directory of Open Access Journals (Sweden)

Ali H Hassan

2010-10-01

Full Text Available Ali H Hassan11Department of Preventive Dental Sciences, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi ArabiaObjective: To evaluate the current pattern of third molar impaction in a sample of Saudi patients.Methods: One thousand thirty-nine orthopantomograms (OPG of patients ranging in age from 19 to 46 years (536 males and 503 females were evaluated to determine the frequency of impacted third molars, their levels of eruption, and their angulations.Results: Four hundred twenty-two (40.5% of the 1039 OPG showed at least one impacted third molar, with no significant difference between males (222; 52.6% and females (200; 47.4% (P = 0.284. The most common number of impacted third molars per OPG was one (72.5%. Impacted third molars were 1.64 times more likely to occur in the mandible than in the maxilla. The most common angulation of impaction in the mandible was the mesial (33.4%, while the most common angulation in the maxilla, was the vertical (49.6%. Level B impaction was the most common in both maxilla (48.2% and mandible (67.7%. There was no significant difference in the frequency of impaction between the right and left sides in both jaws.Conclusion: The pattern of third molar impaction in the western region of Saudi Arabia is characterized by a high prevalence of impaction that is greater in the mandibles and with no sex predilection.Keywords: third molar, impaction, prevalence, Saudi 

Evaluation of the anatomical alterations of lower molars mesial root’s apical third

OpenAIRE

FRÖNER, Izabel Cristina; IMPERADOR, Cristina Aparecida; SOUZA, Luiz Gustavo de

1999-01-01

The anatomical apex of the mesial root of the lower molars presents a morphological complexity related to the number and shape of the root canals as well as of the apical foramen and isthmus presence. The knowledge of the complexity of the endodontic system of the molar root area is essencial to select more carefully the best instrumentation and obturation technique, to obtain a more successful endodontic therapy. A presente pesquisa analisa in vitro as alterações anatômicas dos 4 mm apic...

Treating Intraradicular Pockets of molars

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H. Lotfizade

1987-10-01

Full Text Available It appears that until bone graft has not achieved 100% success, intraradicular diseases remain controversial and therefore, different treatment plans are suggested for them. Treating intraradicular diseases depend on many factors: maxillary molars are more prone to bone loss and have worse prognosis. To assess prognosis more carefully these factors should be considered: 1 bone loss: its apical depth, local or generalized 2 bone condition: buccal, lingual, mesial and distal aspects 3 tooth mobility: grades 2 and 3 have not good prognosis. Crown root ratio is also important. 4 the angle of divergence of roots: the more the roots are divergent, the better the prognosis would be. 5adjacent teeth health 6tooth position in jaws 7 age and general health of the patients 8 oral hygiene In general, teeth with 2 roots can be treated more effectively than 3 root ones. Maxillary first premolars are exceptions that do not respond to the treatments positively. We should look forward to the future investigations and findings.

The Relevance of Employee-Related Ratios for Early Detection of Corporate Crises

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Mario Situm

2014-12-01

Full Text Available The purpose of this study was to analyse whether employee-related ratios derived from accounts have incremental predictive power for the early detection of corporate crises and bankruptcies. Based on the literature reviewed, it can be seen that not much attention has been drawn to this task, indicating that further research is justified. For empirical research purposes, a database of Austrian companies was used for the time period 2003 to 2005 in order to develop multivariate linear discriminant functions for the classification of companies into the two states; bankrupt and non-bankrupt, and to detect the contribution of employee-related ratios in explaining why firms fail. Several ratios from prior research were used as potential predictors. In addition, other separate ratios were analysed, including employee-related figures. The results of the study show that while employee-related ratios cannot contribute to an improvement in the classification performance of prediction models, signs of these ratios within the discriminant functions did show the expected directions. Efficient usage of employees seems to play an important role in decreasing the probability of insolvency. Additionally, two employee-related ratios were found which can be used as proxies for the size of the firm. This had not been identified in prior studies for this factor.

"Precipitation on Nanoparticles": Attractive Intermolecular Interactions Stabilize Specific Ligand Ratios on the Surfaces of Nanoparticles.

Science.gov (United States)

Chu, Zonglin; Han, Yanxiao; Kral, Petr; Klajn, Rafal

2018-04-19

Confining organic molecules to the surfaces of inorganic nanoparticles can induce intermolecular interactions between them, which can affect the composition of the mixed self-assembled monolayers obtained by co-adsorption from solution of two different molecules. Here, we study co-adsorption of two thiolated ligands-a dialkylviologen and a zwitterionic sulfobetaine-that can interact with each other electrostatically, onto gold nanoparticles. Consequently, the nanoparticles favor a narrow range of ratios of these two molecules that is largely independent of the molar ratio in solution. We show that changing the solution molar ratio of two ligands by a factor of ~5,000 affects the on-nanoparticle ratio of these ligands by only 3 times. This behavior is reminiscent of the formation of insoluble inorganic salts (e.g., AgCl), which similarly compensate positive and negative charges upon crystallizing. Our results pave the way towards developing well-defined hybrid organic-inorganic nanostructures. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Partial molar volume of n-alcohols at infinite dilution in water calculated by means of scaled particle theory.

Science.gov (United States)

Graziano, Giuseppe

2006-04-07

The partial molar volume of n-alcohols at infinite dilution in water is smaller than the molar volume in the neat liquid phase. It is shown that the formula for the partial molar volume at infinite dilution obtained from the scaled particle theory equation of state for binary hard sphere mixtures is able to reproduce in a satisfactory manner the experimental data over a large temperature range. This finding implies that the packing effects play the fundamental role in determining the partial molar volume at infinite dilution in water also for solutes, such as n-alcohols, forming H bonds with water molecules. Since the packing effects in water are largely related to the small size of its molecules, the latter feature is the ultimate cause of the decrease in partial molar volume associated with the hydrophobic effect.

[Relationship between first molar caries and eating and tooth brushing habits in elementary school children].

Science.gov (United States)

Fujiwara, Aiko; Takeda, Fumi

2010-11-01

The aim of the present study was to elucidate the relationship between eating and tooth brushing habits in the second grade of elementary school with first molar caries in the third to sixth grades. Subjects were 130 students at one elementary school in the Tokai region who were in the second grade in 2002, for which eating and tooth-brushing habits were ascertained by a self-administered questionnaire survey. A follow-up survey was conducted based on the 2002 to 2006 school dental examination record and analyses were performed on data from 104 students without first molar dental caries in the second grade. The incidences of first molar caries in the third grade were higher among students who ate cookies at least once daily or every 2 to 3 days, compared with those who ate cookies once a week or not at all in the second grade. Incidences were also higher among those whose daily frequency of tooth brushing was once or sometimes compared with twice or three times or more. Furthermore, the incidences of first molar caries in the fourth, fifth and sixth grades were higher among students who ate candy at least once daily or every 2 to 3 days, compared with those who ate candy once a week or not at all in the second grade. The intake frequency of cookies was related to the first molar caries in the third grade, and of candy for that in the fourth to sixth grades. Moreover, first molar caries in the third grade were also related to the daily frequency of second-grade tooth brushing. These findings suggest the importance of measures encouraging lower-grade elementary students to establish and maintain habits of tooth brushing and of limiting consumption of sweets, such as cookies and candy, in order to prevent caries in their permanent teeth during elementary school.

Cl/Br ratios and chlorine isotope evidences for groundwater salinization and its impact on groundwater arsenic, fluoride and iodine enrichment in the Datong basin, China

Energy Technology Data Exchange (ETDEWEB)

Li, Junxia; Wang, Yanxin, E-mail: yx.wang@cug.edu.cn; Xie, Xianjun

2016-02-15

In order to identify the salinization processes and its impact on arsenic, fluoride and iodine enrichment in groundwater, hydrogeochemical and environmental isotope studies have been conducted on groundwater from the Datong basin, China. The total dissolved solid (TDS) concentrations in groundwater ranged from 451 to 8250 mg/L, and 41% of all samples were identified as moderately saline groundwater with TDS of 3000–10,000 mg/L. The results of groundwater Cl concentrations, Cl/Br molar ratio and Cl isotope composition suggest that three processes including water-rock interaction, surface saline soil flushing, and evapotranspiration result in the groundwater salinization in the study area. The relatively higher Cl/Br molar ratio in groundwater from multiple screening wells indicates the contribution of halite dissolution from saline soil flushed by vertical infiltration to the groundwater salinization. However, the results of groundwater Cl/Br molar ratio model indicate that the effect of saline soil flushing practice is limited to account for the observed salinity variation in groundwater. The plots of groundwater Cl vs. Cl/Br molar ratio, and Cl vs δ{sup 37}Cl perform the dominant effects of evapotranspiration on groundwater salinization. Inverse geochemical modeling results show that evapotranspiration may cause approximately 66% loss of shallow groundwater to account for the observed hydrochemical pattern. Due to the redox condition fluctuation induced by irrigation activities and evapotranspiration, groundwater salinization processes have negative effects on groundwater arsenic enrichment. For groundwater iodine and fluoride enrichment, evapotranspiration partly accounts for their elevation in slightly saline water. However, too strong evapotranspiration would restrict groundwater fluoride concentration due to the limitation of fluorite solubility. - Highlights: • Natural high arsenic, fluoride and iodine groundwater co-occur with saline water. �

Cl/Br ratios and chlorine isotope evidences for groundwater salinization and its impact on groundwater arsenic, fluoride and iodine enrichment in the Datong basin, China

International Nuclear Information System (INIS)

Li, Junxia; Wang, Yanxin; Xie, Xianjun

2016-01-01

In order to identify the salinization processes and its impact on arsenic, fluoride and iodine enrichment in groundwater, hydrogeochemical and environmental isotope studies have been conducted on groundwater from the Datong basin, China. The total dissolved solid (TDS) concentrations in groundwater ranged from 451 to 8250 mg/L, and 41% of all samples were identified as moderately saline groundwater with TDS of 3000–10,000 mg/L. The results of groundwater Cl concentrations, Cl/Br molar ratio and Cl isotope composition suggest that three processes including water-rock interaction, surface saline soil flushing, and evapotranspiration result in the groundwater salinization in the study area. The relatively higher Cl/Br molar ratio in groundwater from multiple screening wells indicates the contribution of halite dissolution from saline soil flushed by vertical infiltration to the groundwater salinization. However, the results of groundwater Cl/Br molar ratio model indicate that the effect of saline soil flushing practice is limited to account for the observed salinity variation in groundwater. The plots of groundwater Cl vs. Cl/Br molar ratio, and Cl vs δ"3"7Cl perform the dominant effects of evapotranspiration on groundwater salinization. Inverse geochemical modeling results show that evapotranspiration may cause approximately 66% loss of shallow groundwater to account for the observed hydrochemical pattern. Due to the redox condition fluctuation induced by irrigation activities and evapotranspiration, groundwater salinization processes have negative effects on groundwater arsenic enrichment. For groundwater iodine and fluoride enrichment, evapotranspiration partly accounts for their elevation in slightly saline water. However, too strong evapotranspiration would restrict groundwater fluoride concentration due to the limitation of fluorite solubility. - Highlights: • Natural high arsenic, fluoride and iodine groundwater co-occur with saline water. • Groundwater

Pre-operative assessment of impacted mandibular third molar and inferior alveolar canal using orthopantomograhpy and cone beam computed tomography

Directory of Open Access Journals (Sweden)

Mahmuda Akter

2016-12-01

Full Text Available The aim of this study was to assess the proximity and relation of impacted mandibular third molar and inferior alveolar canal on orthopantomogram and cone beam computed tomography (CBCT. Sixty impacted mandibular third molars having close proximity with the  inferior alveolar canal were included. CBCT images were done to determine the exact location and relationship of impacted third molar tooth and inferior alveolar canal. We assessed the radiographic signs from orthopantomogram, the course of  inferior alveolar canal and proximity to the third molar tooth in CBCT. The buccal course of  inferior alveolar canal was most frequently detected (n=36 in CBCT findings. The impacted lower third molar roots were 55% contact with the  inferior alveolar canal and 45% separate from the canal. On orthopantomogram, the following signs were strongly correlated with actual contact: Superimposed relationship between the third molar and the inferior alveolar canal. CBCT is useful as a presurgical planning in patients with impacted mandibular third molar showing close proximity to the  inferior alveolar canal.

Experimental and predicted data of excess molar enthalpies and excess molar volumes for the ternary system (1,3-dichlorobenzene + benzene + 1-chlorohexane) at T = 298.15 K

International Nuclear Information System (INIS)

Mato, Marta M.; Verdes, Pedro V.; Paz Andrade, M.I.; Legido, José Luis

2014-01-01

Graphical abstract: - Highlights: • Experimental enthalpy and densitiy for the mixture 1,3-dichlorobenzene + benzene + 1-chlorohexane were measured. • The excess molar volumes were calculated from the densities of the pure liquids and their mixtures. • The Cibulka equation was used to correlate the ternary contribution of the excess molar properties. • The experimental data were used to test several empirical equations. - Abstract: Experimental excess molar enthalpies, densities and excess molar volumes for the ternary system {x 1 1,3-dichlorobenzene + x 2 benzene + (1 − x 1 − x 2 ) 1-chlorohexane} have been determined at the temperature of 298.15 K and atmospheric pressure. Values of excess molar enthalpies were measured using a Calvet microcalorimeter, and excess molar volumes were determined from the densities of the pure liquids and mixtures, using a vibrating-tube densimeter. The results were fitted by means of different variable degree polynomials. Smooth representations of the results are presented and used to construct constant contours of excess molar enthalpy and excess molar volume on Roozeboom diagrams. Several empirical expressions that have been suggested for use with parameters and predicting excess properties of ternary mixtures from the experimental binary data were tested

Genetic integration of molar cusp size variation in baboons.

Science.gov (United States)

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

2010-06-01

Many studies of primate diversity and evolution rely on dental morphology for insight into diet, behavior, and phylogenetic relationships. Consequently, variation in molar cusp size has increasingly become a phenotype of interest. In 2007 we published a quantitative genetic analysis of mandibular molar cusp size variation in baboons. Those results provided more questions than answers, as the pattern of genetic integration did not fit predictions from odontogenesis. To follow up, we expanded our study to include data from the maxillary molar cusps. Here we report on these later analyses, as well as inter-arch comparisons with the mandibular data. We analyzed variation in two-dimensional maxillary molar cusp size using data collected from a captive pedigreed breeding colony of baboons, Papio hamadryas, housed at the Southwest National Primate Research Center. These analyses show that variation in maxillary molar cusp size is heritable and sexually dimorphic. We also estimated additive genetic correlations between cusps on the same crown, homologous cusps along the tooth row, and maxillary and mandibular cusps. The pattern for maxillary molars yields genetic correlations of one between the paracone-metacone and protocone-hypocone. Bivariate analyses of cuspal homologues on adjacent teeth yield correlations that are high or not significantly different from one. Between dental arcades, the nonoccluding 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. Copyright 2009 Wiley-Liss, Inc.

Apparent molar heat capacities and apparent molar volumes of Pr(ClO4)3(aq), Gd(ClO4)3(aq), Ho(ClO4)3(aq), and Tm(ClO4)3(aq) at T=(288.15, 298.15, 313.15, and 328.15) K and p=0.1 MPa

International Nuclear Information System (INIS)

Hakin, Andrew W.; Lian Liu, Jin; Erickson, Kristy; Munoz, Julie-Vanessa

2004-01-01

Acidified aqueous solutions of Pr(ClO 4 ) 3 (aq), Gd(ClO 4 ) 3 (aq), Ho(ClO 4 ) 3 (aq), and Tm(ClO 4 ) 3 (aq) were prepared from the corresponding oxides by dissolution in dilute perchloric acid. Once characterized with respect to trivalent metal cation and acid content, the relative densities of the solutions were measured at T=(288.15, 298.15, 313.15, and 328.15) K and p=0.1 MPa using a Sodev O2D vibrating tube densimeter. The relative massic heat capacities of the aqueous systems were also determined, under the same temperature and pressure conditions, using a Picker Flow Microcalorimeter. All measurements were made on solutions containing rare earth salt in the concentration range 0.01 ≤ m/(mol · kg -1 ) ≤ 0.2. Relative densities and relative massic heat capacities were used to calculate the apparent molar volumes and apparent molar heat capacities of the acidified salt solutions from which the apparent molar properties of the aqueous salt solutions were extracted by the application of Young's Rule. The concentration dependences of the isothermal apparent molar volumes and heat capacities of each aqueous salt solution were modelled using Pitzer ion-interaction equations. These models produced estimates of apparent molar volumes and apparent molar heat capacities at infinite dilution for each set of isothermal V phi,2 and C pphi,2 values. In addition, the temperature and concentration dependences of the apparent molar volumes and apparent molar heat capacities of the aqueous rare earth perchlorate salt solutions were modelled using modified Pitzer ion-interaction equations. The latter equations utilized the Helgeson, Kirkham, and Flowers equations of state to model the temperature dependences (at p=0.1 MPa) of apparent molar volumes and apparent molar heat capacities at infinite dilution. The results of the latter models were compared to those previously published in the literature. Apparent molar volumes and apparent heat capacities at infinite dilution

Phase equilibria and excess molar volumes of tetrahydrofuran (1) + deuterium oxide (2)

International Nuclear Information System (INIS)

Lejcek, P.; Matous, J.; Novak, J.P.; Pick, J.

1975-01-01

Vapour + liquid equilibrium at 313.15 and 333.15K, liquid + liquid equilibrium throughout the whole region of limited miscibility, and excess molar volumes at 298.15K have been studied for tetrahydrofuran + deuterium oxide. The mixtures show large positive deviations from Raoult's law and a closed loop of limited miscibility. The modified Redlich-Kister equation has been used for the correlation of the vapour + liquid equilibrium. The computation has been carried out according to a recently proposed procedure which makes it possible to obtain such constants of the correlation relation which are not inconsistent with physical reality, i.e. with the complete miscibility (partial delta 2 G/deltax 1 2 >0) under experimental conditions. Thermodynamic consistency was checked by the classical Redlich-Kister test and the one proposed by Ulrichson and Stevenson. Excess molar volumes are negative at all compositions with a point of inflexion in the water-rich region which indicates the extremes in partial molar volumes. (author)

Restoration of a vertical alveolar bone defect by orthodontic relocation of a mesially impacted mandibular first molar.

Science.gov (United States)

Kim, Sung-Jin; Kim, Jin-Wook; Choi, Tae-Hyun; Lee, Kee-Joon

2015-04-01

An impacted mandibular first molar tends to cause serious bone defects of the adjacent teeth. When choosing between the 2 typical treatment options-extraction or orthodontic relocation of the impacted tooth-the decision should be based on assessment of the prognosis. A 22-year-old man with severe mesioangulation and impaction of the mandibular first molar and a related vertical bone defect on the distal side of the second premolar was treated with extraction of the second molar and orthodontic relocation of the first molar with a retromolar miniscrew. Comprehensive orthodontic treatment involving premolar extraction was conducted. Strategic extraction of the molar and adequate orthodontic movement helped to restore the bone structure on the affected side. This case report suggests the effectiveness of restoration of bone defects by using viable periodontal tissues around the impacted tooth for the longevity of the periodontium. Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Autologous Platelet-rich Plasma after Third Molar Surgery.

Science.gov (United States)

Gandevivala, Adil; Sangle, Amit; Shah, Dinesh; Tejnani, Avneesh; Sayyed, Aatif; Khutwad, Gaurav; Patel, Arpit Arunbhai

2017-01-01

The aim of this study is to compare the efficacy of autologous platelet-rich plasma (PRP) in the third molar impactions, with respect to: pain, swelling, healing, and periodontal status distal to the second molar in patients who need surgical removal of bilateral impacted mandibular third molars. Twenty-five patients of both sexes aged between 16 and 60 years who required bilateral surgical removal of their impacted third molars and met the inclusion criteria were included in the study. After surgical extraction of the third molar, primary closure was performed in the control group, whereas PRP was placed in the socket followed by primary closure in the case group. The outcome variables were pain, swelling, wound healing, and periodontal probe depth that were follow-up period of 2 months. Quantitative data are presented as mean. Statistical significance was checked by t -test. There was a difference in the pain (0.071) and facial swelling (0.184), reduction between test and control on day 3, but it was not found to be significant. Periodontal pocket depth (0.001) and wound healing (0.001) less in case group compared with the control group was found to be significant. The use of PRP lessens the severity of immediate postoperative sequelae and decreases preoperative pocket depth.

Molar Incisor Hypomineralization, Prevalence, and Etiology

Directory of Open Access Journals (Sweden)

Sulaiman Mohammed Allazzam

2014-01-01

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

Densities, molar volumes, and isobaric expansivities of (d-xylose+hydrochloric acid+water) systems

International Nuclear Information System (INIS)

Zhang Qiufen; Yan Zhenning; Wang Jianji; Zhang Hucheng

2006-01-01

Densities of (d-xylose+HCl+water) have been measured at temperature in the range (278.15 to 318.15) K as a function of concentration of both d-xylose and hydrochloric acid. The densities have been used to estimate the molar volumes and isobaric expansivity of the ternary solutions. The molar volumes of the ternary solutions vary linearly with mole fraction of d-xylose. The standard partial molar volumes V 2,φ - bar for d-xylose in aqueous solutions of molality (0.2, 0.4, 0.7, 1.1, 1.6, and 2.1) mol.kg -1 HCl have been determined. In the investigated temperature range, the relation: V 2,φ - bar =c 1 +c 2 {(T/K)-273.15} 1/2 , can be used to describe the temperature dependence of the standard partial molar volumes. These results have, in conjunction with the results obtained in water, been used to deduce the standard volumes of transfer, Δ t V - bar , of d-xylose from water to aqueous HCl solutions. An increase in the transfer volume of d-xylose with increasing HCl concentrations has been explained by the stronger interactions of H + with the hydrophilic groups of d-xylose

Fabrication of steel matrix composites locally reinforced with different ratios of TiC/TiB2 particulates using SHS reactions of Ni-Ti-B4C and Ni-Ti-B4C-C systems during casting

International Nuclear Information System (INIS)

Yang Yafeng; Wang Huiyuan; Liang Yunhong; Zhao Ruyi; Jiang Qichuan

2007-01-01

Steel matrix composites locally reinforced with different molar ratios of in situ TiC/TiB 2 particulates (2:1, 1:1 and 1:2, respectively) have been fabricated successfully utilizing the self-propagating high-temperature synthesis (SHS) reactions of Ni-Ti-B 4 C and Ni-Ti-B 4 C-C systems during casting. Differential thermal analysis (DTA) and X-ray diffraction (XRD) results reveal that the exothermic reactions of the Ni-Ti-B 4 C and Ni-Ti-B 4 C-C systems proceed in such a way that Ni initially reacts with B 4 C and Ti to form Ni 2 B and Ti 2 Ni compounds, respectively, with heat evolution at 1037 deg. C; Subsequently, the external heat and the evolved heat from these exothermic reactions promote the reactions forming TiC and TiB 2 at 1133 deg. C. In the composites reinforced with 1:2 molar ratio of TiC/TiB 2 , almost all TiB 2 grains have clubbed structures, while TiC grains exhibit near-spherical morphologies. Furthermore, TiB 2 grain sizes decrease, with the increase of TiC content. In particular, in the composites reinforced with 2:1 molar ratio of TiC/TiB 2 , it is difficult to find the clubbed TiB 2 grains. Macro-pores and blowholes are absent in the local reinforcing region of the composites reinforced with 1:1 and 1:2 molar ratios of TiC/TiB 2 , while a few macro-pores can be observed in the composite reinforced with 2:1 molar ratio of TiC/TiB 2 . Moreover, the densities of the composites reinforced with 1:1 and 1:2 molar ratios of TiC/TiB 2 are higher than that of the composite reinforced with 2:1 molar ratio of TiC/TiB 2 . The composite reinforced with 1:2 molar ratio of TiC/TiB 2 has the highest hardness and the best wear resistance

Changes in heart rate during third molar surgery

NARCIS (Netherlands)

Hollander, M. H. J.; Schortinghuis, J.; Vissink, A.

2016-01-01

Anxiety is an undesirable psychological phenomenon. Patients are usually anxious when subjected to third molar surgery, but the pattern of anxiety is unknown. The aim of this study was to assess the intensity and course of anxiety during third molar surgery. This study included 48 consecutive

Unusal canal configuration in maxillary and mandibular second molars

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Ramachandran Ragunathan

2016-01-01

Full Text Available This clinical article describes three different case reports of maxillary and mandibular second molars with the unusual anatomy of single root with a single canal and their endodontic management. An unusual case of bilateralism is observed in the first two cases in the form of single-rooted second mandibular molars in both the quadrant of the same patient. The presence of maxillary second molar with single root and single canal in the third case is unusual.

Coronectomy of Deeply Impacted Lower Third Molar: Incidence of Outcomes and Complications after One Year Follow-Up

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Jimoh Olubanwo Agbaje

2015-06-01

Full Text Available Objectives: The purpose of present study was to assess the surgical management of impacted third molar with proximity to the inferior alveolar nerve and complications associated with coronectomy in a series of patients undergoing third molar surgery. Material and Methods: The position of the mandibular canal in relation to the mandibular third molar region and mandibular foramen in the front part of the mandible (i.e., third molar in close proximity to the inferior alveolar nerve [IAN] or not was identified on panoramic radiographs of patients scheduled for third molar extraction. Results: Close proximity to the IAN was observed in 64 patients (35 females, 29 males with an impacted mandibular third molar. Coronectomy was performed in these patients. The most common complication was tooth migration away from the mandibular canal (n = 14, followed by root exposure (n = 5. Re-operation to remove the root was performed in cases with periapical infection and root exposure. Conclusions: The results indicate that coronectomy can be considered a reasonable and safe treatment alternative for patients who demonstrate elevated risk for injury to the inferior alveolar nerve with removal of the third molars. Coronectomy did not increase the incidence of damage to the inferior alveolar nerve and would be safer than complete extraction in situations in which the root of the mandibular third molar overlaps or is in close proximity to the mandibular canal.

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

International Nuclear Information System (INIS)

Hakin, Andrew W.; Liu Jinlian; Erickson, Kristy; Munoz, Julie-Vanessa; Rard, Joseph A.

2005-01-01

Relative densities and relative massic heat capacities have been measured for acidified solutions of Y(NO 3 ) 3 (aq), Pr(NO 3 ) 3 (aq), and Gd(NO 3 ) 3 (aq) at T = (288.15, 298.15, 313.15, and 328.15) K and p = 0.1 MPa. In addition, relative densities and massic heat capacities have been measured at the same temperatures and pressure for Y(NO 3 ) 3 (aq) and Ho(NO 3 ) 3 (aq) solutions without excess acid (n.b. measurements at T = 328.15 K for Ho(NO 3 ) 3 (aq) were not performed due to the limited volume of solution available). Apparent molar volumes and apparent molar heat capacities for the aqueous salt solutions have been calculated from the experimental apparent molar properties of the acidified solutions using Young's rule, whereas the apparent molar properties of the solutions without excess acid were calculated directly from the measured densities and massic heat capacities. The two sets of data for the Y(NO 3 ) 3 (aq) systems provide a check of the internal consistency of the Young's rule approach we have utilised. The concentration dependences of the apparent molar volumes and heat capacities of the aqueous salt solutions have been modelled at each investigated temperature using the Pitzer ion interaction equations to yield apparent molar properties at infinite dilution. Complex formation within the aqueous rare earth nitrate systems is discussed qualitatively by probing the concentration dependence of apparent molar volumes and heat capacities. In spite of the complex formation in the aqueous rare earth nitrate systems, there is a high degree of self-consistency between the apparent molar volumes and heat capacities at infinite dilution reported in this manuscript and those previously reported for aqueous rare earth perchlorates

Three-dimensional space changes after premature loss of a maxillary primary first molar.

Science.gov (United States)

Park, Kitae; Jung, Da-Woon; Kim, Ji-Yeon

2009-11-01

A space maintainer is generally preferred when a primary first molar is lost before or during active eruption of the first permanent molars in order to prevent space loss. However, controversy prevails regarding the space loss after eruption of the permanent first molars. The purpose of this study was to examine spatial changes subsequent to premature loss of a maxillary primary first molar after the eruption of the permanent first molars. Thirteen children, five girls and eight boys, expecting premature extraction of a maxillary primary first molar because of caries and/or failed pulp therapy, were selected. Spatial changes were investigated using a three-dimensional laser scanner by comparing the primary molar space, arch width, arch length, and arch perimeter before and after the extraction of a maxillary primary first molar. Also, the inclination and angulation changes in the maxillary primary canines, primary second molars, and permanent first molars adjacent to the extraction site were investigated before and after the extraction of the maxillary primary first molar in order to examine the source of space loss. There was no statistically significant space loss on the extraction side compared to the control side (P = 0.33). No consistent findings were seen on the inclination and angulation changes on the extraction side. The premature loss of a maxillary primary first molar, in cases with class I molar relationship, has limited influence on the space in permanent dentition.

A New Anatomically Based Nomenclature for the Roots and Root Canals—Part 1: Maxillary Molars

OpenAIRE

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

2012-01-01

Numerous terminologies have been employed in the dental literature to describe the roots and root canal systems of maxillary molars. This multiplicity in naming of roots and canals makes the reader susceptible to misinterpretation and confusion. No consensus thus far has been arrived at for defining the names of roots and root canals in maxillary molars, including their various morphological aberrations. The anatomical relation of roots and their root canals were identified and were subsequen...

Ruptured tubal molar pregnancy

African Journals Online (AJOL)

2011-05-19

May 19, 2011 ... In most instances, moles develop within the uterine cavity, but may occur at ... Patients with tubal molar pregnancy are very difficult to distinguish .... There was a left-sided adnexal mass, whose size could not be appreciated ...

Taurodont molars: Review of literature and radiological features

International Nuclear Information System (INIS)

Saini, T.; Wilson, C. A.

1990-01-01

Taurodontic molar teeth are present as a clinical entity in modem man. This is a suggestion that the occurrence has a racial bias. The importance of the differential diagnosis of teeth with enlarged pulp is discussed, and the possible influence of taurodontic molars on treatment planning is outlined. (author)

Excess molar volumes and isentropic compressibilities of binary

Indian Academy of Sciences (India)

Excess molar volumes (E) and deviation in isentropic compressibilities (s) have been investigated from the density and speed of sound measurements of six binary liquid mixtures containing -alkanes over the entire range of composition at 298.15 K. Excess molar volume exhibits inversion in sign in one binary ...

Three-dimensional cone-beam computed tomography: A new approach to the diagnosis and treatment planning of impacted mandibular third molars

International Nuclear Information System (INIS)

Kanazirska, P.; Yordanov, G.; Angelova, I.; Kanazirski, N.

2017-01-01

Cone Beam Computed Tomography (CBCT) is a relatively new method in dental practice which raises a more precise diagnosis and correct treatment plan. The image of the impacted teeth and surrounding structures with CBCT are with better quality and informativity than the conventional imaging-diagnostic methods . The use of CBCT to determine the ratio of the impacted teeth to the mandibular canal is necessary for the prevention of complications associated with iatrogenic trauma to the vascular- nerve bundle. The aim of this study was to determine the anatomic relationship between the roots of impacted third molars and mandibular canal using CBCT imaging. The studied patients with impacted third molars of the mandible are 127, aged 17 through 60.They were examined with Cone-beam Computed Tomography (CBCT). From the 195 impacted third molar with the - higher frequency are those in which the channel is below their roots-107 teeth (54.9%). The second frequency are the teeth where the channel is located lingually-57 (29.2%). Follow the teeth, in which the channel has a buccal location-25 (12.8%). With the lowest frequency are cases in which the mandibular canal is between the roots of impacted teeth-6 teeth (3.1%).At 132 teeth (67.7%) mandibular canal is at a distance of 1 mm. At 63 teeth (32.3%) the channel is at a distance of over 1 mm. The high resolution cuts in different planes and three-dimensional reconstructions made substantially as set forth preferred for different specialists in dentistry. Precise measurements of the bone around the mandibular canal prevent damage to neurovascular bundle. This makes the method preferred for planning appropriate treatment. Key words: Cone Beam Computed Tomography. Impacted Third Molars. Mandibular Canal [bg

Subcutaneous emphysema during third molar surgery: a case report.

Science.gov (United States)

Romeo, Umberto; Galanakis, Alexandros; Lerario, Francesco; Daniele, Gabriele Maria; Tenore, Gianluca; Palaia, Gaspare

2011-01-01

Extraction of third molars is the most common surgical procedure performed in oral surgery on a daily basis and, despite surgical skills and expertise, complications may occur. Complications observed during or after third molar removal may include pain, swelling, bleeding, infection, sinus perforation and nerve damage. Fortunately, with a proper management and a good surgical technique, the incidence of such events is low. Subcutaneous emphysema associated with dental extraction occurs when the air from the high-speed dental handpiece is forced into the soft tissue through the reflected flap and invades the adjacent tissues, leading to swelling, crepitus on palpation and occasionally spreading through the tissue spaces of the fascial planes. Although rare, iatrogenic subcutaneous emphysema can have serious and potentially life-threatening consequences. Care should be taken when using air-driven handpieces. The access of air into the facial tissues is not limited to tooth extractions, but may also occur through other portals of entrance, such as endodontically treated teeth, periodontium and lacerations of intraoral soft tissues. When subcutaneous emphysema occurs, it must be quickly diagnosed and properly managed to reduce the risk of further complications. This report presents a case of subcutaneous emphysema occurred during extraction of a mandibular third molar extraction with the use of an air turbine handpiece. Case management is described and issues relative to the diagnosis and prevention of this surgical complication are discussed.

Prevention of alveolar osteitis after third molar surgery: Comparative ...

African Journals Online (AJOL)

Prevention of alveolar osteitis after third molar surgery: Comparative study of the ... for surgical extraction of lower third molar were prospectively, consecutively, and ... Information on demographic, types and level of impaction, indications for ...

A study of the eruption of the mandibular first permanent molar

OpenAIRE

河野, 美砂子; Kohno, Misako

1995-01-01

The object of this study was to know what positional changes of the mandibular first permanent molars occur just before their gingival emergence. The eruptive process of the mandibular first molars was investigated during the period from alveolareruption to preoraleruption. The subjects were 14 patients whose second primary molars were prematurely lost in one side and remained on the other side. Longitudinal oblique cephalograms were used to estimate the eruptive process of the first molars o...

A geometric morphometric analysis of hominin lower molars: Evolutionary implications and overview of postcanine dental variation.

Science.gov (United States)

Gómez-Robles, Aida; Bermúdez de Castro, José María; Martinón-Torres, María; Prado-Simón, Leyre; Arsuaga, Juan Luis

2015-05-01

Lower molars have been extensively studied in the context of hominin evolution using classic and geometric morphometric analyses, 2D and 3D approaches, evaluations of the external (outer enamel surface) and internal anatomy (dentine, pulp chamber, and radicular canals), and studies of the crown and root variation. In this study, we present a 2D geometric morphometric analysis of the crown anatomy of lower first, second, and third molars of a broad sample of hominins, including Pliocene and Lower, Middle, and Upper Pleistocene species coming from Africa, Asia, and Europe. We show that shape variability increases from first to second and third molars. While first molars tend to retain a relatively stable 5-cusped conformation throughout the hominin fossil record, second and third molars show marked distal reductions in later Homo species. This trend to distal reduction is similar to that observed in previous studies of premolars and upper second and third molars, and points to a correlated reduction of distal areas across the whole postcanine dentition. Results on lower molar variation, as well as on other postcanine teeth, show certain trends in European Pleistocene populations from the Atapuerca sites. Middle Pleistocene hominins from Sima de los Huesos show Neanderthal affinities and strong dental reduction, especially in the most distal molars. The degree of dental reduction in this population is stronger than that observed in classic Neanderthals. Homo antecessor hominins from Gran Dolina-TD6 have primitive lower teeth that contrast with their more derived upper teeth. The evolutionary implications of these dental affinities are discussed in light of recent paleogenetic studies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Double versus single cartridge of 4% articaine infiltration into the retro-molar area for lower third molar surgery.

Science.gov (United States)

Sawang, Kamonpun; Chaiyasamut, Teeranut; Kiattavornchareon, Sirichai; Pairuchvej, Verasak; Bhattarai, Bishwa Prakash; Wongsirichat, Natthamet

2017-06-01

There are no studies regarding 4% articaine infiltration injection into the retro-molar area for an impacted lower third molar (LITM) surgery. This study aimed to evaluate the efficacy of infiltration using 1.7 ml (single cartridge: SC) of 4% articaine versus 3.4 ml (double cartridges: DC) of 4% articaine with 1:100,000 epinephrine in LITM surgery. This study involved 30 healthy patients with symmetrical LITM. The patients were assigned to receive either a DC or SC of 4% articaine with 1:100,000 epinephrine as a local anesthetic for each operation. Onset, duration, profoundness, need for additional anesthetic administration, total volume of anesthetic used, vitality of the tooth, and pain score during operation were recorded. The DC of 4 % articaine had a significantly higher success rate (83.3%) than did the SC (53.3%; P molar region can be an alternative anesthetic for LITM surgery.

Magnetic resonance imaging of third molars: developing a protocol suitable for forensic age estimation.

Science.gov (United States)

De Tobel, Jannick; Hillewig, Elke; Bogaert, Stephanie; Deblaere, Karel; Verstraete, Koenraad

2017-03-01

Established dental age estimation methods in sub-adults study the development of third molar root apices on radiographs. In living individuals, however, avoiding ionising radiation is expedient. Studying dental development with magnetic resonance imaging complies with this requirement, adding the advantage of imaging in three dimensions. To elaborate the development of an MRI protocol to visualise all third molars for forensic age estimation, with particular attention to the development of the root apex. Ex vivo scans of porcine jaws and in vivo scans of 10 volunteers aged 17-25 years were performed to select adequate sequences. Studied parameters were T1 vs T2 weighting, ultrashort echo time (UTE), fat suppression, in plane resolution, slice thickness, 3D imaging, signal-to-noise ratio, and acquisition time. A bilateral four-channel flexible surface coil was used. Two observers evaluated the suitability of the images. T2-weighted images were preferred to T1-weighted images. To clearly distinguish root apices in (almost) fully developed third molars an in plane resolution of 0.33 × 0.33 mm 2 was deemed necessary. Taking acquisition time limits into account, only a T2 FSE sequence with slice thickness of 2 mm generated images with sufficient resolution and contrast. UTE, thinner slice T2 FSE and T2 3D FSE sequences could not generate the desired resolution within 6.5 minutes. Three Tesla MRI of the third molars is a feasible technique for forensic age estimation, in which a T2 FSE sequence can provide the desired in plane resolution within a clinically acceptable acquisition time.

Apparent molar volumes and compressibilities of selected electrolytes in dimethylsulfoxide

International Nuclear Information System (INIS)

Warminska, Dorota; Grzybkowski, Waclaw

2010-01-01

Densities at T = (293.15, 298.15, 303.15, 313.15, 323.15, and 333.15) K and sound velocities at T = 298.15 K of tetraphenylphosphonium bromide, sodium tetraphenylborate, sodium bromide, and sodium perchlorate in dimethylsulfoxide have been measured over the composition range from (0 to 0.3) mol . kg -1 . From these data, apparent molar volumes and apparent molar isentropic compressibilities at infinite dilution as well as the expansibilities have been evaluated. The results have been discussed in terms of employing tetraphenylphosphonium tetraphenylborate as a reference electrolyte in splitting the limiting apparent molar volumes and apparent molar isentropic compressibilities into ionic contributions.

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

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Mónica Nova Delgado

2016-05-01

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

Detection of Mesiobuccal Canal in Maxillary Molars and Distolingual Canal in Mandibular Molars by Dental CT: A Retrospective Study of 100 Cases

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Sushma Rathi

2010-01-01

Full Text Available Objective. To detect presence of MB2 canal in maxillary molars and distolingual canal in mandibular molars by Dental CT. Material and Methods. A retrospective study of 100 Dental CTs was done. Axial and paraxial images obtained were used to assess the presence of MB2 canal in maxillary molars and distolingual canal in mandibular molars. Results. The youngest patient was of 11 years while the eldest patient was of 77 years. Males were 58 in number and females were 42 in number. MB2 canals were present in 57 patients and distolingual canal was present in 18 patients. Maximum MB2 canals were present in age group between 51 and 60 years, while distolingual canals were present in age group of 21–30 years. Conclusion. Dental CT allows adequate visualization of variation in root canal morphology and can be important diagnostic tool for successful endodontic therapy.

Prevalence and severity of molar incisor hypomineralization in children aged 11-16 years of a city in Karnataka, Davangere

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M Kirthiga

2015-01-01

Full Text Available Introduction: Molar incisor hypomineralization (MIH describes the clinical picture of hypomineralization of systemic origin affecting one or more first permanent molar. There is a rarity of prevalence studies in Indian population. Objectives: The main aim of this study was to investigate the prevalence of MIH in a population of South Indian children. Settings and Design: A cross-sectional epidemiological survey, included 2000 children aged 11-16 years chosen by stratified random sampling from government and private schools of Davangere, a city in South India. Materials and Methods: Evaluation of MIH and decayed, missing and filled teeth was carried out in these children by a calibrated examiner. The severity of hypomineralization was recorded according to the Wetzel and Reckel scale. Statistical Analysis: Chi-square test was used to analyze the categorical data. P ≤ 0.05 was considered for statistical significance. Results: About 8.9% of all examined children showed at least one ill-structured first permanent molar in terms of MIH. The male and female ratio was found to be 1:1.1. The decreasing order of occurrence of MIH affected teeth were permanent maxillary molars, maxillaryincisors, mandibular molars and the mandibular incisors. Conclusion: The prevalence of MIH in the permanent dentition of south Indian children was 8.9%. There is a need for a proper planned preventive and restorative program with regard to the increasing prevalence of MIH.

Effectiveness of various sterilization methods of contaminated post-fitted molar band

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Anggia Tridianti

2013-06-01

Full Text Available Background: Molar band as anchoring device may be contaminated during the fitting process. Thus, decontamination process is essential to prevent cross-infection between patients. Purpose: The objective of this research was to determine the amount of bacteria in molar band post-fitted on the patient teeth, after previously undergone pre-sterilization using alcohol and ultrasonic cleaning bath followed by sterilization using dry heat oven and steam autoclave, in order to find the best method in decontamination of post-fitted molar band. Methods: Four molar bands which already fitted on one patient then divided evenly into two groups. The first group was pre-sterilized using alcohol. One of the bands then sterilized using dry heat oven, while the other one was sterilized using steam autoclave. The second group was pre-sterilized using ultrasonic cleaning bath. One band from this group then sterilized using dry heat oven and the other was sterilized using steam autoclave. The next step was to immerse all the bands in a phosphate-buffered saline solution. Using micropipette, the solution was retrieved and dropped upon a petri dish containing Brain Heart Infusion broth. The dish was then stored in an incubator for 24 hours, prior to counting the number of bacteria existed. The same methods were used to the rest of the patients, with total 128 molar bands from 32 patients. Results: There was a profound difference in numbers of bacteria found between those methods of sterilization. However, there was a non significant difference between the two groups which were at the alcohol-steam autoclave group and at the ultrasonic cleaning bath-steam autoclave group. Conclusion: This study showed that steam autoclave is better than for sterilizing molar band, as it left the minimal amount of bacteria in post-fitted molar band.Latar belakang: Molar band merupakan suatu alat penjangkaran yang dapat mengalami kontaminasi selama proses fitting band, sehingga perlu

Orthodontic space closure after first molar extraction without skeletal anchorage.

Science.gov (United States)

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

2011-03-01

The aim of the study was an analysis of effects and side-effects during mesialization of second molars after extraction of the first permanent molars using the anterior dentition/premolars (PM) as an anchorage unit. A total of 35 patients were examined retrospectively who had undergone unilateral or bilateral first permanent molar extraction in the upper or lower arch due to carious lesions. Space closure was carried out in all cases through mesialization of the second molar using an elastic chain fixed to an edgewise stainless steel archwire and tying the anterior dentition/PM together with a continuous laceback ligature. Tooth movement was assessed from lateral cephalograms, orthopantomograms (OPGs) and images of the patient's study casts taken before and after the end of therapy. Space closure after first molar extractions by mesialization of the second molars without skeletal anchorage was largely achieved by bodily forward movement of the teeth, including a small tipping component or tooth-uprighting component when molars were already mesially inclined. Unilateral and bilateral mesialization of the second molars led to retrusion in the maxilla and mandible [(∆incl.=-3.6° (max., bil.), ∆incl.=-4.2° (mand., bil.)] and to translational retraction [(∆s=-2.3 mm (max., bil.), ∆s=-1.6 mm (mand., bil.)] of the incisors. Examination of the soft tissues revealed an increased posterior displacement of the upper and lower lips to the esthetic line [(∆s=-2.8 mm (max. bil.), ∆s=-2.2 mm (mand., bil.)]. In cases of unilateral mesialization less than 50% of the patients had a slight midline deviation in the mandible towards the extraction side. Side effects during mesialization of the second molars without skeletal anchorage in the anterior dentition/PM were observed primarily affecting the incisors integrated into the anterior anchorage unit. These side-effects resulted in posterior displacement of the soft tissues, including a change in profile. This must be

Sex assessment efficacy of permanent maxillary first molar cusp dimensions in Indians

Directory of Open Access Journals (Sweden)

Achla Bharti Yadav

2015-01-01

Full Text Available Background: The human first maxillary molar provides clues about evolution and is functionally important. It has four main cusps, and each cusp has an independent growth pattern and different evolutionary background. Though less explored, the analysis based on measurement of each cusp appears to be more meaningful biologically than conventional measurements of the whole crown. Aim: This study aimed to demonstrate the extent of sexual dimorphism in permanent maxillary first molar cusp diameters and their potential utility in sex prediction among Indians using logistic regression analysis (LRA. Materials and Methods: The mesiodistal and buccolingual (BL crown diameters along with cusp dimensions and cusp indices of right maxillary first molar were measured in an Indian sample (149 males, 151 females; age range of 18–30 years. The possible sex dimorphism in these parameters was evaluated, and LRA was performed to ascertain their usefulness in sex prediction. Results: BL crown dimension and the hypocone (distolingual cusp showed the highest sexual dimorphism. The combination of metacone and hypocone, i.e., distal cusp diameters among cusp parameters showed the highest accuracy (61.3%. While, on combining all the crown and cusp diameters together the overall accuracy was raised (64.3%. Conclusion: This study supports the ontogeny hypothesis suggesting that early-forming mesial cusps demonstrate less sexual variation as compared to subsequently formed distal cusps in the maxillary molar. Though the sex identification accuracy for cusp diameters of the permanent maxillary first molar in Indians is relatively moderate (≈61%, it can be used as an adjunct for sexing of adult Indians in forensic contexts.

Microleakage of different adhesive systems in primary molars ...

African Journals Online (AJOL)

Background and aim: This study aimed to examine the microleakage of class V cavities of primary molars prepared by either a conventional dental bur or Er:YAG laser and one of two different adhesive systems. Methods: A total of 50 tooth samples from primary molars were used in this study. They were randomly assigned ...

The anatomical relationship between the roots of mandibular second molars and the inferior alveolar nerve.

Science.gov (United States)

Chong, B S; Quinn, A; Pawar, R R; Makdissi, J; Sidhu, S K

2015-06-01

To evaluate the anatomical relationship between the roots of mandibular second molars and the inferior alveolar nerve (IAN) in relation to the risk of potential nerve injury during root canal treatment. Cone-beam computed tomography (CBCT) images from the patient record database at a dental hospital were selected. The anonymized CBCT images were reconstructed and examined in three planes (coronal, axial and sagittal) using 3D viewing software. The relationship between each root apex of mandibular second molars and the IAN was evaluated by measuring the horizontal and vertical distances from coronal CBCT sections, and the actual distance was then calculated mathematically using Pythagoras' theorem. In 55% of the 272 mandibular second molar roots evaluated, from a total of 134 scans, the distance between the anatomical root apex and the IAN was ≤3 mm. In over 50% of the cases evaluated, there was an intimate relationship between the roots of mandibular second molars and the inferior alveolar nerve (IAN). Therefore, root canal treatment of mandibular second molars may pose a more significant potential risk of IAN injury; necessary precautions should be exercised, and the prudent use of CBCT should be considered if an intimate relationship is suspected. © 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Comparison of second molar eruption patterns in patients with skeletal Class II and skeletal Class I malocclusions.

Science.gov (United States)

Brin, Ilana; Camasuvi, Semin; Dali, Nasser; Aizenbud, Dror

2006-12-01

The eruptive positions of the second molars in Class I and Class II malocclusions were studied. Pretreatment records of 221 patients with a mean age of 11.3 years were evaluated. About 19% of them had skeletal Class I, 31% had skeletal maxillary Class II, and 50% had skeletal mandibular Class II malocclusions. The mean values of the dental and chronologic ages of the subjects were similar. The eruptive positions in relation to a reference line, the developmental stages of the patients' second molars and dental ages were recorded from the panoramic roentgenograms. The distribution of the various developmental stages in each malocclusion group was similar, and no association between skeletal malocclusion and dental developmental stage of the second molars was encountered. The eruptive position of the maxillary second molars was more occlusal only in the oldest maxillary Class II group, above 12 years of age (P = .02). These results support, in part, previous reports suggesting that the maxillary second molars may erupt earlier in patients with skeletal maxillary Class II malocclusions.

Standard molar enthalpies of formation of monochloroacetophenone isomers

International Nuclear Information System (INIS)

Ribeiro da Silva, Manuel A.V.; Amaral, Luisa M.P.F.

2010-01-01

The standard (p 0 =0.1MPa) molar enthalpies of formation of the liquids 2'-, 3'-, and 4'-chloroacetophenones were derived from the standard molar energies of combustion, in oxygen, to yield CO 2 (g) and HCl . 600H 2 O(l), at T = 298.15 K, measured by rotating-bomb combustion calorimetry. The Calvet microcalorimetry was used to measure the enthalpies of vaporization of the three compounds. These two thermodynamic parameters yielded the standard molar enthalpies of formation of the chloroacetophenone isomers, in the gaseous phase, at T = 298.15 K. (table) An empirical scheme, developed by Cox, was used to estimate the gas-phase enthalpies of formation and the obtained values were compared with the experimental ones.

The molar hydrodynamic volume changes of factor VIIa due to GlycoPEGylation

DEFF Research Database (Denmark)

Plesner, Bitten; Westh, Peter; Hvidt, Søren

2011-01-01

The effects of GlycoPEGylation on the molar hydrodynamic volume of recombinant human rFVIIa were investigated using rFVIIa and two GlycoPEGylated recombinant human FVIIa derivatives, a linear 10 kDa PEG and a branched 40 kDa PEG, respectively. Molar hydrodynamic volumes were determined by capillary......, that the molar hydrodynamic volume of the conjugated protein is not just an addition of the molar hydrodynamic volume of the PEG and the protein. The molar hydrodynamic volume of the GlycoPEGylated protein is larger than the volume of its composites. These results suggest that both the linear and the branched...

Movimentação de molares inferiores ancorados em mini-parafusos Mandibular molar uprighting, using mini-screw as anchorage

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Rosana Canteras Di Matteo

2005-08-01

Full Text Available Freqüentemente a movimentação ortodôntica exige recursos adicionais de ancoragem. Os mini-parafusos têm-se apresentado como uma possível solução. O propósito deste trabalho foi estabelecer um método para a verticalização de molares inferiores inclinados para mesial, utilizando ancoragem em mini-parafusos colocados na região de linha oblíqüa externa da mandíbula. Foram selecionados três pacientes entre 40 a 48 anos (dois do gênero feminino, um do gênero masculino, com molares inferiores inclinados para mesial e distalmente posicionados às áreas edêntulas. Os pacientes foram tratados ortodonticamente durante um período de 6 a 12 meses, com técnica ortodôntica MD3. Mini-parafusos de titânio foram colocados bilateralmente com anestesia local. Uma incisão sobre a linha oblíqüa externa da mandíbula, medindo aproximadamente 1 cm foi realizada em cada lado, distalmente aos molares inclinados. Após descolamento muco-periosteal, mini-parafusos foram implantados e foram realizadas suturas deixando suas cabeças exteriorizadas. Uma semana após a remoção das suturas, cargas ortodônticas (entre 150 a 200 gramas/força foram aplicadas através de forças elásticas. Verificamos que alguma inflamação foi observada ao redor dos mini-parafusos, mas foi controlada com procedimentos de higienização. O procedimento cirúrgico é simples, podendo ser realizado pelo ortodontista; as formas dimensionais dos mini-parafusos são adequadas e estes são de fácil remoção após uso. Concluímos que o uso de mini-parafusos representa uma alternativa efetiva de ancoragem ortodôntica na verticalização de molares inferiores.Tooth movement frequently requires additional anchorage resources. Mini-screws have been used as a possible solution to this matter. The purpose of this study was to establish a method of mandibular molar uprighting, using mini-screw as anchorage, positioned on the mandibular external oblique line, behind and

Microstructure of a tribosphenic molar - comparative analysis

OpenAIRE

ŠPOUTIL, František

2010-01-01

The proposed thesis concerns in the study of tribosphenic molar, the key apomorphy of mammalian clade, mainly in structure and development of its enamel coat. As the main model species served us European vespertilionid bat Myotis myotis. The aims of this thesis are: (1) to describe structure and microstructure of enamel in tribosphenic molars in detail; (2) to compare it with unicuspid teeth of the same dentition; (3) to describe mineralization process and enamel maturation in insectivorous d...

Distribution and characteristics of molar-incisor hypomineralization

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Janković Svjetlana

2014-01-01

Full Text Available Background/Aim. Developmental disorders of teeth are the problems that are becoming more present in pediatric dentistry, especially on first permanent molars and incisors. Molar Incisor Hypomineralization (MIH is proposed term for this phenomenon. The aim of this study was to establish the MIH prevalence in children living in the Foča municipality (Bosnia and Herzegovina as well as to assess characteristics and expression of hypomineralization within the tested population. Methods. A total of 141 children from the Foča municipality, 8 years of age, were included in this study. Criteria according to Weerhejm have been used for diagnosis of hypomineralization: demarcated opacity (DO, post-eruptive breakdown (PEB, atypical restoration (AR, extracted molars due to MIH (E-MIH and unerupted tooth (UT. Level and the prominence of color changes have been determined for patients with DO, PEB and AR. Results. MIH in this area was present in 12.8% of children. The prevalence of MIH changes expressed in percentages was as follows: DO was at 9.2%, PEB in 3.5%, AR in 5.6%, while E-MIH was 5.6%. A total of 9.9% of the examinees had mild, 5.6% moderate, and 7.8% severe form of MIH. White form of MIH defects was found in 9.9% of the examinees, white-yellow one in 5.6% and yellow-brown color in 3.5% of the examined children. These changes were more often present in the lower jaw (60.3%. In total, 6.4% of children had these changes present only on molars, while 6.4% of them both on molars and incisors simultaneously. Conclusion. A total of 12.8% of the examinees with MIH is not to be disregarded. With timely diagnosis, prevention and therapy complications could be avoided or mitigated.

Fatigue resistance of CAD/CAM resin composite molar crowns.

NARCIS (Netherlands)

Shembish, F.A.; Tong, H.; Kaizer, M.; Janal, M.N.; Thompson, V.P.; Opdam, N.J.M.; Zhang, Y.

2016-01-01

OBJECTIVE: To demonstrate the fatigue behavior of CAD/CAM resin composite molar crowns using a mouth-motion step-stress fatigue test. Monolithic leucite-reinforced glass-ceramic crowns were used as a reference. METHODS: Fully anatomically shaped monolithic resin composite molar crowns (Lava

A Retrospective Radiographic Survey of Pathology Associated with Impacted Third Molars among Patients Seen in Oral & Maxillofacial Surgery Clinic of College of Dentistry, Riyadh.

Science.gov (United States)

Khawaja, Naveed Ahmad; Khalil, Hesham; Parveen, Kauser; Al-Mutiri, Abdulmajeed; Al-Mutiri, Saif; Al-Saawi, Abdullah

2015-04-01

The purpose of this study is to determine the type and frequency of pathological conditions around third molar teeth among randomly selected patient's records in Oral and Maxillofacial Surgery, College of Dentistry, King Saud University, Riyadh. Totally, 281 patient panoramic radiographs were selected with detectable pathology among 570 files of patients seen in oral and maxillofacial surgery clinics 2 years retrospectively. Almost 17-55 years age (mean age 25.43) was selected. The following radiographs were analyzed for all pathology associated impacted teeth; dental caries, bone resorption, periodontitis, and apical pathology. The study found caries, external bone resorption and periodontitis are highly frequent to mesioangular and horizontal in mandibular impacted third molar compared to maxillary impacted third molar. Overall result evaluated that tooth #28 related periodontitis is significant (P = 0.021), and tooth #38 related bone resorption, tooth #48 related root caries, bone resorption and apical pathology are highly significant (P = 0.000) comparing to others. This study also concluded the high frequency of root caries, bone resorption and apical pathology reported in relation to mandibular impacted third teeth. Significant results were also achieved with periodontitis in relation to mesiangular and vertical angulation of left impacted maxillary third molars. Prophylactic removal of impacted third molars is recommended in many studies to avoid future risk of associated pathology. Retained asymptomatic impacted third molars imply pathology that could be difficult in later ages as less morbidity in younger ages.

The relative worst order ratio applied to paging

DEFF Research Database (Denmark)

Boyar, Joan; Favrholdt, Lene Monrad; Larsen, Kim Skak

2007-01-01

The relative worst order ratio, a new measure for the quality of on-line algorithms, was recently defined and applied to two bin packing problems. Here, we apply it to the paging problem and obtain the following results: We devise a new deterministic paging algorithm, Retrospective-LRU, and show...

Endodontic treatment of an unusual connation of permanent mandibular molars: a case report.

Science.gov (United States)

Liu, Shengbo; Fan, Bing; Peng, Bin; Fan, Mingwen; Bian, Zhuan

2006-10-01

A 27-year-old patient with an anomalous mandibular molar was referred for endodontic therapy. Clinical and radiographic examination revealed the connation of a second mandibular molar with a third molar. Challenging endodontic therapy was performed in the unusual connated molars. A 2-year recall showed good treatment result.

Standard molar enthalpies of formation of monochloroacetophenone isomers

Energy Technology Data Exchange (ETDEWEB)

Ribeiro da Silva, Manuel A.V., E-mail: risilva@fc.up.p [Centro de Investigacao em Quimica, Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal); Amaral, Luisa M.P.F. [Centro de Investigacao em Quimica, Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal)

2010-12-15

The standard (p{sup 0}=0.1MPa) molar enthalpies of formation of the liquids 2'-, 3'-, and 4'-chloroacetophenones were derived from the standard molar energies of combustion, in oxygen, to yield CO{sub 2}(g) and HCl . 600H{sub 2}O(l), at T = 298.15 K, measured by rotating-bomb combustion calorimetry. The Calvet microcalorimetry was used to measure the enthalpies of vaporization of the three compounds. These two thermodynamic parameters yielded the standard molar enthalpies of formation of the chloroacetophenone isomers, in the gaseous phase, at T = 298.15 K. (table) An empirical scheme, developed by Cox, was used to estimate the gas-phase enthalpies of formation and the obtained values were compared with the experimental ones.

Three-dimensional analysis of third molar development to estimate age of majority.

Science.gov (United States)

Márquez-Ruiz, Ana Belén; Treviño-Tijerina, María Concepción; González-Herrera, Lucas; Sánchez, Belén; González-Ramírez, Amanda Rocío; Valenzuela, Aurora

2017-09-01

Third molars are one of the few biological markers available for age estimation in undocumented juveniles close the legal age of majority, assuming an age of 18years as the most frequent legal demarcation between child and adult status. To obtain more accurate visualization and evaluation of third molar mineralization patterns from computed tomography images, a new software application, DentaVol©, was developed. Third molar mineralization according to qualitative (Demirjian's maturational stage) and quantitative parameters (third molar volume) of dental development was assessed in multi-slice helical computed tomography images of both maxillary arches displayed by DentaVol© from 135 individuals (62 females and 73 males) aged between 14 and 23years. Intra- and inter-observer agreement values were remarkably high for both evaluation procedures and for all third molars. A linear correlation between third molar mineralization and chronological age was found, with third molar maturity occurring earlier in males than in females. Assessment of dental development with both procedures, by using DentaVol© software, can be considered a good indicator of age of majority (18years or older) in all third molars. Our results indicated that virtual computed tomography imaging can be considered a valid alternative to orthopantomography for evaluations of third molar mineralization, and therefore a complementary tool for determining the age of majority. Copyright © 2017 The Chartered Society of Forensic Sciences. Published by Elsevier B.V. All rights reserved.

Comparative analysis of the first permanent molars caries prevalence in younger and older school children

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Stojković Branislava B.

2012-01-01

Full Text Available Introduction. The data on the health-condition of the first permanent molars among children in our region is scarce. Therefore, the need for more thorough analysis of the state of health of these teeth in the children from our region imposes itself, along with the need to determine the most critical period in which a significant increase in caries prevalence of these teeth takes place. Aim. The aim of the research was to perform a comparative analysis of the prevalence, average rate and structure of decay, missed and filled first permanent molars in the children of the younger school age in relation to those of the older school age. Material and methods. The research included 1.119 examinees, aged from 7 to 14 years. Examinees were divided into two groups according to their age: examinees of the younger school age and older school age. Dental check-up of the students was performed by means of a dental probe and mirror and the health condition of the examined teeth was registered by means of Klein-Palmer's DMF system. Results. The research determined high values of the examined parameters of the first permanent molars caries prevalence which increases with the age of the examinees. In the examinees of the age of 8, 9, and 10, statistically more significant values of the examined teeth caries prevalence parameters were registered, in relation to the examinees of seven years of age. In the examinees of the older school age, statistically significantly higher values were registered only for TCI and ACI and only in the examinees aged 14 in relation to the examinees aged 11. With the age, the percent of decay is decreases, while the percent of filled and extracted first permanent molars increases. Conclusion. Results show that the period between 7 and 10 years of age is the most critical and the most important period for the implementation of preventive-prophylactic measures aimed to preserve the health of the first permanent molars.

Management of large losses of substances molars

OpenAIRE

Reynal, Florence

2016-01-01

This work aims to compare the different coronary restorative materials used for large tooth losses in primary molars. The first part of this thesis is dedicated to a description of the four main materials used in coronary restorations of molars : amalgam, glass-ionomer cements, resin-based composite and pedodontic crown. The second part is a systematic review of the literature. The aim is to compare the long-term survival rates of different restoration techniques, in order to help the practit...

Prevalence of molar incisor hypomineralization in school children aged 8-12 years in Chennai

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Savitha Deepthi Yannam

2016-01-01

Full Text Available Objective: To investigate the prevalence and severity of molar incisor hypomineralization (MIH. Materials and Methods: A sample of 2,864 students aged 8-12 years were selected from government and private schools in Chennai. MIH was diagnosed clinically based on the diagnostic criteria established by the European Academy of Pediatric Dentistry (EAPD 2003. Results: A total of 277 children (9.7% had MIH. There was statistically significant difference in prevalence related to age but there was no statistical difference in prevalence with respect to gender. Conclusion: Prevalence of MIH was 9.7% in the child population residing in Chennai. Males and females were equally affected. The rate of occurrence and severity of MIH are more in the right mandibular first molar. The severity of MIH is more in molars compared to incisors (P < 0.001 and is more in government schools compared to private schools (P = 0.002.

Ab initio calculations of partial molar properties in the single-site approximation

DEFF Research Database (Denmark)

Ruban, Andrei; Skriver, Hans Lomholt

1997-01-01

We discuss the application of the single-site approximation in calculations of partial molar quantities, e.g., impurity solution energy, segregation energy, and effective chemical potential, which are related to a variation of the composition of an alloy or its nonequivalent parts. We demonstrate...

Molaren Inzisiven Hypomineralisation und Milchmolaren Hypomineralisation - klinisches Erscheinungsbild, Prävalenz und deren Ursachen - Molar Incisor Hypomineralisation and Deciduous Molar Hypomineralisation - clinical appearance, prevalence and determinants for its occurrence

NARCIS (Netherlands)

Elfrink, M.E.C.; Weerheijm, K.L.

2012-01-01

Background: Molar Incisor Hypomineralisation (MIH) and Deciduous Molar Hypomineralisation (DMH) are frequently occurring dental problems in children. Children with MIH have demarcated opacities in their erupting first permanent molars often in combination with demarcated opacities in their permanent

Management of inflammatory complications in third molar surgery: A ...

African Journals Online (AJOL)

Background: Pain, swelling and trismus are common complications associated with third molar surgery. These complications have been reported to have an adverse effect on the quality of life of patients undergoing third molar surgery. Objective: To review the different modalities of minimizing inflammatory complications in ...

Effect of age, sex and level of surgical difficulty on inflammatory complications after third molar surgery.

Science.gov (United States)

Osunde, Otasowie D; Saheeb, Birch D

2015-03-01

Patients' factors such as age and sex and surgical variables such as level of difficulty have been linked with surgical outcome in third molar surgery. The aim of this study was to determine the effect of these variables on inflammatory complications in patients undergoing third molar surgery. Patients referred to our institution for surgical extraction of their impacted lower third molar between January 2007 and December 2008 were the subjects of the study. Patients' demographics as well as types of impaction, indication and level of difficulty based on Pederson criteria were obtained. Post operative pain, swelling and mouth opening limitation were evaluated at day 1, day 2, day 3, day 5 and 1 week after the surgery and analyzed. A p value of less than 0.05 was considered significant. A total of 150 patients aged 16-38 years (25.9 ± 4.47) met the inclusion criteria. Male accounted for 66 (44.0 %) while females were 84 (56.0 %), giving male to female ratio of 1:1.3. Age, sex and difficulty index had no effect on pain and trismus throughout the periods of postoperative evaluation (p > 0.05). Postoperative swelling was not affected by gender but patients above 25 years who had high scores of difficulty index had more facial swelling. The results of this study shows that age, gender and the level of surgical difficulty have no effect on pain and mouth opening limitation after third molar surgery.

ASIC subunit ratio and differential surface trafficking in the brain.

Science.gov (United States)

Wu, Junjun; Xu, Yuanyuan; Jiang, Yu-Qing; Xu, Jiangping; Hu, Youjia; Zha, Xiang-ming

2016-01-08

Acid-sensing ion channels (ASICs) are key mediators of acidosis-induced responses in neurons. However, little is known about the relative abundance of different ASIC subunits in the brain. Such data are fundamental for interpreting the relative contribution of ASIC1a homomers and 1a/2 heteromers to acid signaling, and essential for designing therapeutic interventions to target these channels. We used a simple biochemical approach and semi-quantitatively determined the molar ratio of ASIC1a and 2 subunits in mouse brain. Further, we investigated differential surface trafficking of ASIC1a, ASIC2a, and ASIC2b. ASIC1a subunits outnumber the sum of ASIC2a and ASIC2b. There is a region-specific variation in ASIC2a and 2b expression, with cerebellum and striatum expressing predominantly 2b and 2a, respectively. Further, we performed surface biotinylation and found that surface ASIC1a and ASIC2a ratio correlates with their total expression. In contrast, ASIC2b exhibits little surface presence in the brain. This result is consistent with increased co-localization of ASIC2b with an ER marker in 3T3 cells. Our data are the first semi-quantitative determination of relative subunit ratio of various ASICs in the brain. The differential surface trafficking of ASICs suggests that the main functional ASICs in the brain are ASIC1a homomers and 1a/2a heteromers. This finding provides important insights into the relative contribution of various ASIC complexes to acid signaling in neurons.

Effect of different hapten-carrier conjugation ratios and molecular orientations on antibody affinity against a peptide antigen

DEFF Research Database (Denmark)

Pedersen, M. K.; Sørensen, Nanna Skall; Heegaard, Peter M. H.

2006-01-01

-based assay systems and in deciding whether a vaccine-induced antibody response will be protective. With ovalbumin as a carrier protein and a peptide (7.2NY) representing a 19 ammo acid sequence from the E. coli-derived Verotoxin 2e as a model hapten we investigated whether it was possible to influence...... ten dines at two-weeks intervals with low doses of the eight conjugates, Blood samples collected between each immunisation were analysed by ELISA for specific antibody titres and relative affinities. With both types of conjugations, the anti-peptide antibody titres increased in response to increasing...... for terminal conjugation. Thus, it appears that the molar ratio of a peptide and its carrier may affect the resulting antibody affinities, and that a conjugation ratio between a terminally Conjugated peptide and its carrier approaching one will result in relatively high antibody affinities. Furthermore...

Chemometric study of the effects of PtRu:BH4-molar ratio and solvent used in the preparation of PtRu/C electrocatalysts for for direct methanol fuel cell anodes

Energy Technology Data Exchange (ETDEWEB)

Polanco, N.S.O.; Neto, A.O.; Spinace, E.V. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Tusi, M.M. [Universidade Regional Integrada do Alto Uruguai e das Missoes (URI), Santiago, RS (Brazil); Brandalise, M. [Instituto Federal Fluminense (IFF), Campos dos Goyracazes, RJ (Brazil)

2014-07-01

PtRu/C electrocatalysts were prepared by borohydride reduction method and a chemometric study was performed to evaluate the influence of the solvent (water and isopropyl alcohol) and amount of reducing agent (PtRu:BH4- molar ratios of 5 and 15) in maximum power density. In borohydride reduction method, a solution containing sodium hydroxide and sodium borohydride (NaBH4) is added to a mixture containing water, isopropyl alcohol, metallic precursors and the carbon support Vulcan XC72. The obtained materials were characterized by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Membrane Electrode Assemblies (MEA's) were produced and tests in single direct methanol fuel cells were performed. The amount of sodium borohydride used in the reduction showed more influence on the maximum power density than the change of solvent of the reaction. (author)

Radiographic evaluation of third-molar development in relation to the chronological age of Turkish children in the southwest Eastern Anatolia region.

Science.gov (United States)

Karataş, Orhan H; Öztürk, Fırat; Dedeoğlu, Numan; Çolak, Cemil; Altun, Oğuzhan

2013-10-10

To study the chronological age of third-molar mineralisation of Turkish children from the southwest Eastern Anatolia region, the Demirjian staging method was used to determine the stage of the mineralisation of four third molars (18, 28, 38 and 48) and to compare third-molar development by sex and age with the results of previous studies. The study comprised 832 Turkish children from the southwest Eastern Anatolia region aged 6-16 years based on radiological evidence from digital orthopantomograms. The mean age of the 832 patients was 11.03±1.98 years, with 424 males (mean age, 10.97±1.97) and 408 females (mean age, 11.09±2.00). The orthopantomograms were scored by two observers. The Wilcoxon matched-pairs signed-rank test used to assess intra- and inter-observer assessment revealed strong agreement between both observers' measurements. Statistical analysis of the association between sex and age was performed with the Mann-Whitney U-test and the Wilcoxon test. Regression analysis was performed to obtain regression formulae for calculating the dental and the chronological age. The statistical analysis showed a strong correlation between age and third-molar development in males (R(2)=0.61) and females (R(2)=0.63). New equations (age=7.49+0.69, development stage (DS) 38+0.70, DS18) were derived for estimation of the chronological age. The results showed that there was no significant difference in mineralisation between 18 and 28 and 38 and 48 in males or females. For both sexes, the dental age was lower than the chronological age. Males reached the developmental stages earlier than females. In the whole population, the boys' and the girls' dental ages were 0.84 years and 0.16 years earlier, respectively, than their chronological ages. The use of third-molar teeth as a developmental marker is suitable, particularly when comparing the obtained standard deviation with other skeletal-age calculation techniques. Copyright © 2013 Elsevier Ireland Ltd. All rights

Comparison of wintertime CO to NOx ratios to MOVES and MOBILE6.2 on-road emissions inventories

Science.gov (United States)

Wallace, H. W.; Jobson, B. T.; Erickson, M. H.; McCoskey, J. K.; VanReken, T. M.; Lamb, B. K.; Vaughan, J. K.; Hardy, R. J.; Cole, J. L.; Strachan, S. M.; Zhang, W.

2012-12-01

The CO-to-NOx molar emission ratios from the US EPA vehicle emissions models MOVES and MOBILE6.2 were compared to urban wintertime measurements of CO and NOx. Measurements of CO, NOx, and volatile organic compounds were made at a regional air monitoring site in Boise, Idaho for 2 months from December 2008 to January 2009. The site is impacted by roadway emissions from a nearby busy urban arterial roads and highway. The measured CO-to-NOx ratio for morning rush hour periods was 4.2 ± 0.6. The average CO-to-NOx ratio during weekdays between the hours of 08:00 and 18:00 when vehicle miles travelled were highest was 5.2 ± 0.5. For this time period, MOVES yields an average hourly CO-to-NOx ratio of 9.1 compared to 20.2 for MOBILE6.2. Off-network emissions are a significant fraction of the CO and NOx emissions in MOVES, accounting for 65% of total CO emissions, and significantly increase the CO-to-NOx molar ratio. Observed ratios were more similar to the average hourly running emissions for urban roads determined by MOVES to be 4.3.

Apparent molar volumes and compressibilities of electrolytes and ions in γ-butyrolactone

International Nuclear Information System (INIS)

Krakowiak, Joanna; Wawer, Jarosław; Farmas, Aleksander

2012-01-01

Highlights: ► Density and speed of sound for salts solutions in γ-butyrolactone were measured. ► The apparent molar volumes and compressibilities have been determined. ► The limiting molar quantities are split into independent ionic contributions. ► These data are used to describe ion–solvent interactions. - Abstract: The densities of tetraphenylphosphonium bromide, sodium tetraphenylborate, lithium perchlorate, sodium perchlorate and lithium bromide in γ-butyrolactone at (288.15, 293.15, 298.15, 303.15, 308.15 and 313.15) K and speed of sound at 298.15 K have been measured. From these data apparent molar volumes V Φ at (288.15, 293.15, 298.15, 303.15, 308.15 and 313.15) K and the apparent molar isentropic compressibility K S,Φ , at T = 298.15 K of the salts have been determined. The apparent molar volumes and the apparent molar isentropic compressibilities were fitted to the Redlich, Rosenfeld and Mayer equation as well as to the Pitzer and Masson equations yielding infinite dilution data. The obtained limiting values have been used to estimate the ionic data of the standard partial molar volume and the standard partial isentropic compressibility in γ-butyrolactone solutions.

Autotransplantation of a mandibular third molar: A case report

Directory of Open Access Journals (Sweden)

Elham Najafi

2017-09-01

Full Text Available Tooth autotransplantation defines as transition of one tooth from one position to another, in same individual. It is a biological procedure in which teeth have the potential to induce alveolar bone growth. It can be applied in patients before adolescence growth is finished. It significantly reduces time and cost compared to implants. Healing rapidly occurs and function is regained almost immediately. Our case was a 15-year-old male that his left mandibular third molar transplanted to the second molar sight after extraction of second molar because of unrestorable crown. During 9 month follow up transplanted tooth was asymptomatic, functional and responsive to sensibility tests. (Cold test, EPT.

Variant Root Morphology of Third Mandibular Molar in Normal and ...

African Journals Online (AJOL)

isaac kipyator

2017-11-12

Nov 12, 2017 ... ABSTRACT. The mandibular third molar poses a challenge to dental surgeons due to it's unpredictable morphology ... treatment in the School of Dental Sciences since 2010. ... mandibular third molar include presence of three.

Prevalência de perda precoce de molares decíduos: estudo retrospectivo = Prevalence of early loss of deciduous molars: a retrospective study

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Alessandro Leite Cavalcanti

2008-07-01

Full Text Available Este estudo retrospectivo determinou a prevalência da perda precoce demolares decíduos em pacientes atendidos na clínica de Odontopediatria da Universidade Estadual da Paraíba. Foram examinados 515 prontuários, sendo os dados registrados em um formulário. Foram analisadas as variáveis: gênero, idade, tipo de molar decíduo perdido,arcada dentária (maxilar ou mandibular e lado (direito e esquerdo. Observou-se que a prevalência de perda precoce foi de 15,1%, existindo uma distribuição similar entre os gêneros. Em relação à idade da criança, a maior freqüência de perda acometeu pacientescom sete anos (32,1%. Houve distribuição equitativa da perda dentária entre as arcadas superior e inferior, com 43,6% cada uma, sendo o lado esquerdo o mais acometido (41%. O segundo molar superior esquerdo foi o mais acometido (17,9%, seguido do primeiromolar decíduo superior direito (16,1%. Pode-se concluir que a prevalência de perda precoce foi baixa e que os molares decíduos superiores foram os dentes mais comumente perdidos.This retrospective study determined the prevalence of early loss of deciduous molars in patients enrolled at the Pediatric Dentistry clinic at the State University of Paraíba. A review of 515 patient records were analyzed, registered in a form. The following variables were analyzed: gender, age, type of deciduous molar loss, region (maxilla or mandible and side (right and left. It was observed that the prevalence of early tooth loss was 15.1% and there was a similar distribution between the genders. In regard to age, the greatest frequency of tooth loss involved patients at 7 years old (32.1%. There was a similar distribution of tooth loss between the maxilla and mandible regions, at 43.6% each, with the left side being themost involved (41%. The second upper left deciduous molar was the most commonly missing tooth (17.9%, followed by the first upper right deciduous molar (16.1%. It can be concluded that the

Western Saudi adolescent age estimation utilising third molar development.

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

2014-07-01

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. The orthopantomograms of 130 individuals (males and females), were examined, and the stage of third molar development were evaluated. 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 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. 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.

To the issue of temperature-dependent behavior of standard molar volumes of components in the binary system (water + tetrahydrofuran) at ambient pressure

International Nuclear Information System (INIS)

Ivanov, Evgeniy V.

2014-01-01

Graphical abstract: The standard molar volume of tetrahydrofuran (THF) in water, V THF ∘ (■), is a close-to-linear function of temperature and becomes increasingly appreciable with rising of the latter. Herewith the molar volume of pure THF, V THF (□), is retained to be larger, as compared to V THF ∘ , over all the temperature range studied. - Highlights: • Densities of aqueous THF at nine temperatures from (278.15 to 318.15) K were measured. • Temperature-dependent standard molar volumes of THF in water were calculated. • The analysis of excess standard molar volumes in the (water + THF) system was made. • The use of Redlich–Kister equation to obtain standard molar volumes is discussed. - Abstract: This report presents a comparative analysis of temperature-dependent data on density of both dilute aqueous solutions of tetrahydrofuran (THF) and dilute solutions of water in THF, as well as standard molar volumes of water or THF as a solute. For this purpose, new results on studying the volume-related properties of THF in a water-rich region at temperatures from (278.15 to 318.15) K, with a step of 5 K, and at the ambient pressure have been derived densimetrically. In discussion, some comments on previously published investigations, being related to temperature-dependent changes in the solution density and standard molar volumes of components of the system (water + THF), have been made

Orthodontic Replacement of Lost Permanent Molar with Neighbor Molar: A Six-Year Follow-Up

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Taisa Boamorte Raveli

2017-01-01

Full Text Available Extraction is very frequent indication in orthodontic planning, especially when there are crowding, biprotrusion, and aesthetically unpleasant profiles. Next to extraction comes space closure, which represents a challenge for orthodontists because of extended treatment time, discomfort created for the patient, tissue tolerance, and stability concerns. When it comes to what mechanics to choose for space closure, loops present two major advantages in relation to sliding mechanics: absence of abrasion and possibility to reach pure dental translation. A case is presented where an adult female patient with early loss of the first lower permanent molars, minor lower crowding, and tooth biprotrusion was treated with upper first bicuspids extraction along with upper and lower space closure done with T-loops to promote best space closure control in order to correct the malocclusion and enhance facial aesthetics.

Orthodontic Replacement of Lost Permanent Molar with Neighbor Molar: A Six-Year Follow-Up

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Shintcovsk, Ricardo Lima; Knop, Luegya Amorim Henriques; Sampaio, Luana Paz

2017-01-01

Extraction is very frequent indication in orthodontic planning, especially when there are crowding, biprotrusion, and aesthetically unpleasant profiles. Next to extraction comes space closure, which represents a challenge for orthodontists because of extended treatment time, discomfort created for the patient, tissue tolerance, and stability concerns. When it comes to what mechanics to choose for space closure, loops present two major advantages in relation to sliding mechanics: absence of abrasion and possibility to reach pure dental translation. A case is presented where an adult female patient with early loss of the first lower permanent molars, minor lower crowding, and tooth biprotrusion was treated with upper first bicuspids extraction along with upper and lower space closure done with T-loops to promote best space closure control in order to correct the malocclusion and enhance facial aesthetics. PMID:29318054

Age of patient at the extraction of the third molar.

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Kautto, A; Vehkalahti, M M; Ventä, I

2018-04-13

The purpose of this study was to assess the age of patients at the time of extraction of third molars. Our data included all routine and surgical extractions of third molars (n=8199 teeth) performed by general and specialist dentists of the public oral health services of the city of Helsinki over the period 2013-2014. Measurements included patient's age, gender, the identified third molar, the type of anaesthesia, the method of extraction, and the diagnosis at extraction. Patients' ages ranged from 10 to 99years. We found significant differences between younger and older age groups: third molar extractions occurred more often for women than for men below the age of 30years (Page of 40years, but the corresponding prevalences reversed after the age of 40years. Diagnoses at extraction differed between younger and older patients. We conclude that the treatment pattern of third molars at public health services varies greatly over a lifetime, and that a greater variety exists than had been reported previously from oral and maxillofacial units. Copyright © 2018 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

[Application of hand-use ProTaper instruments in endodontic treatment of molar canals].

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Ma, Sui-qi; Xie, Qian; Zhou, Yin-feng

2010-07-01

To evaluate the application of hand-use ProTaper instruments in endodontic treatment of molar canals. A total of 203 permanent molars were randomly divided into the experimental group (99 molars) and control group (104 molars) prepared by hand-use ProTaper instruments and standard stainless steel K-file, respectively. The molars in the two groups were obturated by cold lateral condensation technique. The root canal preparation and obturation were evaluated by radiograph, and the working time of preparation and post-operative emergencies were analyzed. The preparation time in the experimental group was obviously shorter than that in the control group (Phand-use ProTaper instruments may improve the effect of root canal treatment of the molars and shorten the working time and reduce the post-operative emergencies.

The partial molar volume of BeSO4 in aqueous solutions

International Nuclear Information System (INIS)

Kuschel, F.; Seidel, J.

1981-01-01

The density of aqueous solutions of BeSO 4 has been measured as a function of the mole fraction in the range of 0.02487 x 10 -2 to 6.3082 x 10 -2 . From the results obtained the molar volume and partial molar volume have been calculated and the limiting value of the partial molar volume for Be 2+ was extrapolated in accordance with the Debye-Hueckel law

Fibrous epulis associated with impacted lower right third molar

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Ni Putu Mira Sumarta

2009-12-01

Full Text Available Background: Epulis or epulides are lesions associated with gingival tissues. Fibrous epulis is a type of hyperplastic fibrous tissue mass located at the gingival which is slow growing, painless, having same color as the oral mucosa and firm on palpation. Anterior regions of the oral cavity are the frequently affected sites as these areas are more prone to be affected by calculus deposition and poor plaque control due to frequent teeth malposition. Removal of any irritating factors and excision of the lesion are the usual treatments. Purpose: This case report presents a rare case of fibrous epulis which occurred in the posterior region of the oral cavity and associated with impacted lower third molar. Case: A case of fibrous epulis at the lower right third molar area of three months duration is presented. The mass was slow growing, painless and on examination it was a pedunculated mass overlying the unerupted lower right third molar, having same color with the oral mucosa and firm on palpation. Clinically, the lesion was diagnosed as fibrous epulis associated with impacted lower right third molar. Case management: The treatment were surgical excision of the epulis and removal of the lower right third molar. The histopathology result showed tissue with squamous epithelial lining, achanthotic fibrous connective tissue, mononuclear inflammatory cells and few capillaries without signs of malignancy. This is consistent with the diagnosis of fibrous epulis. Conclusion: Fibrous epulis, although frequently occurred at the anterior region of the oral cavity, may rarely grow at the area of lower third molar. This phenomenon supports the theory that epulis can grow on any surface of oral mucous membrane as long as local irritants are present.

Pendulum Therapy of Molar Distalization in Mixed Dentition.

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

2016-01-01

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

Supplemental root in a mandibular first molar: a rarity

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Poonam Mahajan

2011-04-01

Full Text Available Anatomic variations are common in human dentition. A clear understanding of these variations is very important for success of endodontic treatment. A dentist should be aware of these anatomic variations as this can affect the treatment outcome. A case of endodontic therapy is presented in which inability to locate an anatomically rare supplemental canal of a three rooted mandibular first molar resulted in treatment failure. A 21-year-old female reported with pain and swelling in relation to lower right first molar. An intra oral periapical radiograph revealed 3 roots; the first canal of the mesial root and a canal of one of the distal roots were found to be treated endodontically, which were infraobturated but the canal of the 2nd distal root had not been treated. The radiograph revealed periapical radiolucency and widening of periodontal space. Prior to starting the endodontic treatment the clinician must be aware of the anatomic variations in tooth pulp morphology and also the importance of preoperative radiographs cannot be underscored.

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

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

2015-05-01

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

Middle mesial canal of the permanent mandibular first molars: an anatomical challenge directly related to the outcome of endodontic treatment.

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Perlea, Paula; Nistor, Cristina Coralia; Imre, Marina; Gheorghiu, Irina Maria; Iliescu, Alexandru Andrei

2017-01-01

To effectively clean and shape the mandibular permanent first molars it is mandatory to understand in detail their complex internal anatomy. The middle mesial canal is an additional canal located between the usual mesiobuccal and mesiolingual canals in the mesial root of mandibular first molars. The incidence of the middle mesial canal, its relationship with main canals of the mesial root and the possibility for it to be negotiated is an important practical issue in endodontics. To identify the presence of this canal is mandatory. Accordingly, a modified endodontic access, the use of the operating microscope and periapical radiographs in two different horizontal projections are indicated to enhance the long-term favorable outcome of the endodontic treatment.

The prevalence and pattern of deciduous molar hypomineralization and molar-incisor hypomineralization in children from a suburban population in Nigeria

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Temilola, Oluwaseyi Dada; Folayan, Morenike Oluwatoyin; Oyedele, Titus

2015-01-01

Background Molar Incisor Hypoplasia (MIH) and Deciduous Molar Hypoplasia (DMH) have significant impact on the quality of life of affected individuals. The objective of the study was to determine the prevalence, pattern and clinical presentation of MIH and DMH in children resident in Ile-Ife, Nigeria, and their association with sex and socioeconomic status of the children. Methods Information on age, sex and socioeconomic status was collected from 563 children aged 3 to 5?years and 8 to 10?yea...

Management of Unilaterally Impacted Permanent Mandibular First, Second and Third Molars

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Rohit Mehrotra

2014-01-01

Full Text Available This case report describes the treatment of a teenage patient with simultaneous impaction of all three right mandibular permanent molars. The impacted first and second mandibular molars were surgically exposed and orthodontically erupted into good alignment and occlusion while the impacted third molar in the same quadrant was extracted. The unique clinical presentation, various treatment alternatives, the decision making process in finalizing the treatment plan and its clinical implementation are discussed.

Probabilidad de retención de segundos molares permanentes mandibulares (Estudio piloto

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Paulo Sandoval Vidal

Full Text Available Objetivos: Determinar la frecuencia del segundo molar mandibular permanente (MM2 con probabilidad de impactación, en un grupo de pacientes de Ortodoncia de Temuco, Chile. Método: Estudio de corte transversal, con muestra por conveniencia. Se revisaron 2095 fichas de individuos de ambos sexos, con ausencia de patología sindrómica. Los datos recolectados se obtuvieron de radiografías panorámicas. Se midió el ángulo del segundo molar con respecto al plano oclusal, la invasión distal del primer molar y la distancia entre distal del primer molar y el borde anterior de la rama mandibular. Resultados: El promedio de edad de los pacientes relevados fue de 10 años. Se observó un 1,43% de probabilidad de retención de MM2 (n=30; en promedio y el plano el ángulo MM2 resultó de 27° el izquierdo y 26° el derecho; la invasión de MM2 en distal del primer molar resultó de 1,5 mm; el ángulo entre MM2 y el planos oclusal es de 123°; la distancia entre la cara distal del primer molar y el borde anterior de la rama mandibular fue 13 mm. Conclusiones: Existe una baja prevalencia de segundos molares mandibulares permanentes con probabilidad de impactación. La invasión a la cara distal del primer molar fue mayor en pacientes con riesgo de impactación

Apparent molar heat capacities and apparent molar volumes of Pr(ClO{sub 4}){sub 3}(aq), Gd(ClO{sub 4}){sub 3}(aq), Ho(ClO{sub 4}){sub 3}(aq), and Tm(ClO{sub 4}){sub 3}(aq) at T=(288.15, 298.15, 313.15, and 328.15) K and p=0.1 MPa

Energy Technology Data Exchange (ETDEWEB)

Hakin, Andrew W. E-mail: hakin@uleth.ca; Lian Liu, Jin; Erickson, Kristy; Munoz, Julie-Vanessa

2004-09-01

Acidified aqueous solutions of Pr(ClO{sub 4}){sub 3}(aq), Gd(ClO{sub 4}){sub 3}(aq), Ho(ClO{sub 4}){sub 3}(aq), and Tm(ClO{sub 4}){sub 3}(aq) were prepared from the corresponding oxides by dissolution in dilute perchloric acid. Once characterized with respect to trivalent metal cation and acid content, the relative densities of the solutions were measured at T=(288.15, 298.15, 313.15, and 328.15) K and p=0.1 MPa using a Sodev O2D vibrating tube densimeter. The relative massic heat capacities of the aqueous systems were also determined, under the same temperature and pressure conditions, using a Picker Flow Microcalorimeter. All measurements were made on solutions containing rare earth salt in the concentration range 0.01 {<=} m/(mol {center_dot} kg{sup -1}) {<=} 0.2. Relative densities and relative massic heat capacities were used to calculate the apparent molar volumes and apparent molar heat capacities of the acidified salt solutions from which the apparent molar properties of the aqueous salt solutions were extracted by the application of Young's Rule. The concentration dependences of the isothermal apparent molar volumes and heat capacities of each aqueous salt solution were modelled using Pitzer ion-interaction equations. These models produced estimates of apparent molar volumes and apparent molar heat capacities at infinite dilution for each set of isothermal V{sub phi,2} and C{sub pphi,2} values. In addition, the temperature and concentration dependences of the apparent molar volumes and apparent molar heat capacities of the aqueous rare earth perchlorate salt solutions were modelled using modified Pitzer ion-interaction equations. The latter equations utilized the Helgeson, Kirkham, and Flowers equations of state to model the temperature dependences (at p=0.1 MPa) of apparent molar volumes and apparent molar heat capacities at infinite dilution. The results of the latter models were compared to those previously published in the literature. Apparent

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

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

2014-08-01

Preservation of the primary dentition until the normal time of exfoliation is one of the most important factor involved in preventive and interceptive dentistry. The premature loss of second primary molar before the eruption of permanent first molar can create a significant arch space/tooth size discrepancy. Distal shoe space maintainer is a valuable part of the Paediatric Dentist's armamentarium in those cases where the second primary molar is prematurely lost and it helps to guide the first permanent molar into place. Conventional design poses various limitations in cases of premature loss of multiple deciduous molars. Thus, it is required to modify the conventional designs according to the needs of the patient. This case report describes an innovative modification of distal shoe appliance in cases of premature loss of multiple deciduous molars. In the present case, modification of distal shoe space maintainer was advocated because of inadequate abutments caused due to multiple loss of deciduous molars. Bilateral design of distal shoe was planned for unilateral loss of deciduous molars.

Fusion or gemination? An unusual mandibular second molar

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Angela Jordão Camargo

2016-01-01

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

Mandibular second molar with 3 mesial canals and a radix paramolaris

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N Ragavendran

2014-01-01

Full Text Available Mandibular first molar commonly has two roots, the mesial and the distal root. Surprisingly in some mandibular first molar has an unusual extra third root in between mesial and distal root. This extra root is the most commonly seen in lingual side and is called as radix entomolaris. If this extra root is seen on the buccal side, it is termed as radix paramolaris (RP, which is a very rare phenomenon. Recently, various case report studies has shown the presence of third canal in the mesial and distal roots of mandibular molars. They are named as middle mesial and middle distal canal, respectively. Here, we present a case report of mandibular second molar showing three canals in the mesial root and a RP.

An aegialodontid upper molar and the evolution of mammal dentition.

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Lopatin, Alexey V; Averianov, Alexander O

2006-08-25

The most obvious key synapomorphy of the therian mammals is the tribosphenic pattern of their molars. Tribosphenic teeth are capable of both shearing and grinding, which substantially increase effectiveness of food processing and, in turn, permit evolution of a wide range of dietary specializations. Functional tribospheny developed repeatedly during mammalian evolution but was successful only in the Boreosphenida. The earliest stage in the development of boreosphenidan tribospheny has remained poorly understood, being documented only by lower molars of aegialodontids. Here, we report a known upper molar of an aegialodontid mammal, Kielantherium, from the Early Cretaceous of Mongolia.

Standard molar enthalpies of formation of three N-benzoylthiocarbamic-O-alkylesters

International Nuclear Information System (INIS)

Ribeiro da Silva, Manuel A.V.; Santos, Luis M.N.B.F.; Schroeder, Bernd; Dietze, Frank; Beyer, Lothar

2004-01-01

The standard (p 0 =0.1 MPa) molar enthalpies of combustion in oxygen of three crystalline N-benzoylthiocarbamic-O-alkylesters, PhCONHCSOR, R=Et (Hbtcee), n-Bu (Hbtcbe), n-Hex (Hbtche), were measured at T=298.15 K by rotating bomb calorimetry. The standard molar enthalpies of sublimation of the three compounds were measured using Calvet microcalorimetry. These values were used to derive the standard molar enthalpies of formation of the compounds in their crystalline and gaseous phases, respectively

Requirement of alveolar bone formation for eruption of rat molars

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Wise, Gary E.; He, Hongzhi; Gutierrez, Dina L.; Ring, Sherry; Yao, Shaomian

2011-01-01

Tooth eruption is a localized event that requires a dental follicle (DF) to regulate the resorption of alveolar bone to form an eruption pathway. During the intra-osseous phase of eruption, the tooth moves through this pathway. The mechanism or motive force that propels the tooth through this pathway is controversial but many studies have shown that alveolar bone growth at the base of the crypt occurs during eruption. To determine if this bone growth (osteogenesis) was causal, experiments were designed in which the expression of an osteogenic gene in the DF, bone morphogenetic protein-6 (BMP6), was inhibited by injection of the 1st mandibular molar of the rat with an siRNA targeted against BMP6. The injection was followed by electroporation to promote uptake of the siRNA. In 45 first molars injected, eruption either was delayed or completely inhibited (7 molars). In the impacted molars, an eruption pathway formed but bone growth at the base of the crypt was greatly reduced as compared to the erupted first molar controls. These studies show that alveolar bone growth at the base of the crypt is required for tooth eruption and that BMP6 may be an essential gene for promoting this growth. PMID:21896048

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

Science.gov (United States)

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

2011-01-01

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

Management of a maxillary first molar having atypical anatomy of two roots diagnosed using cone beam computed tomography.

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Sharma, Sarang; Mittal, Meenu; Passi, Deepak; Grover, Shibani

2015-01-01

Most often, a clinician working on maxillary first molar when anticipates an aberration thinks of an extra canal but rarely does he preempt fewer canals. Maxillary first molar is a tooth, which has been extensively reviewed with respect to its external and internal morphology. Abundant literature related to its anatomy is available, but reports on incidence of two roots and two root canals in maxillary first molar are very limited. Here, a case of maxillary first molar is presented that had two roots: one palatal root with Type I canal configuration and one bulbous fused buccal root with Type V canal configuration; a unique root and canal configuration not seen in any of the earlier reported cases. Diagnosis of root canal aberrancy and subsequently, accurate management of the tooth was greatly facilitated by cone beam computed tomography (CBCT) scan. The relevance of CBCT in improving treatment prognosis is greatly emphasized in this report.

Apparent molar volumes and apparent molar heat capacities of Pr(NO{sub 3}){sub 3}(aq), Gd(NO{sub 3}){sub 3}(aq), Ho(NO{sub 3}){sub 3}(aq), and Y(NO{sub 3}){sub 3}(aq) at T (288.15, 298.15, 313.15, and 328.15) K and p = 0.1 MPa

Energy Technology Data Exchange (ETDEWEB)

Hakin, Andrew W. [Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive, Lethbridge, Alberta, T1K 3M4 (Canada)]. E-mail: hakin@uleth.ca; Liu Jinlian [Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive, Lethbridge, Alberta, T1K 3M4 (Canada); Erickson, Kristy [Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive, Lethbridge, Alberta, T1K 3M4 (Canada); Munoz, Julie-Vanessa [Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive, Lethbridge, Alberta, T1K 3M4 (Canada); Rard, Joseph A. [Energy and Environment Directorate, Lawrence Livermore National Laboratory, University of California, Livermore, CA 94550 (United States)

2005-02-01

Relative densities and relative massic heat capacities have been measured for acidified solutions of Y(NO{sub 3}){sub 3}(aq), Pr(NO{sub 3}){sub 3}(aq), and Gd(NO{sub 3}){sub 3}(aq) at T = (288.15, 298.15, 313.15, and 328.15) K and p = 0.1 MPa. In addition, relative densities and massic heat capacities have been measured at the same temperatures and pressure for Y(NO{sub 3}){sub 3}(aq) and Ho(NO{sub 3}){sub 3}(aq) solutions without excess acid (n.b. measurements at T = 328.15 K for Ho(NO{sub 3}){sub 3}(aq) were not performed due to the limited volume of solution available). Apparent molar volumes and apparent molar heat capacities for the aqueous salt solutions have been calculated from the experimental apparent molar properties of the acidified solutions using Young's rule, whereas the apparent molar properties of the solutions without excess acid were calculated directly from the measured densities and massic heat capacities. The two sets of data for the Y(NO{sub 3}){sub 3}(aq) systems provide a check of the internal consistency of the Young's rule approach we have utilised. The concentration dependences of the apparent molar volumes and heat capacities of the aqueous salt solutions have been modelled at each investigated temperature using the Pitzer ion interaction equations to yield apparent molar properties at infinite dilution. Complex formation within the aqueous rare earth nitrate systems is discussed qualitatively by probing the concentration dependence of apparent molar volumes and heat capacities. In spite of the complex formation in the aqueous rare earth nitrate systems, there is a high degree of self-consistency between the apparent molar volumes and heat capacities at infinite dilution reported in this manuscript and those previously reported for aqueous rare earth perchlorates.

Estudios físico-químicos de miscelas de aceites vegetales XIV. Volumen molar, refracción molar y viscosidad de disoluciones de estearato de metilo en ciciohexano, hexano, tetracloroetileno o tricloroetileno

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Muñoz Cueto, María J.

1991-02-01

Full Text Available In the miscelies studied, molar volume and molar refraction values show linear dependence with the molar fraction of methyl stearate. Viscosity values fit Hildebrand's modified equation, where the "V_o" parameter is a linear function of the molar fraction of methyl stearate. Regarding with this three physico-chemical properties, the mixtures studied behave like ideal mixtures of two organic liquids without ionization.

En todas las miscelas estudiadas los valores del volumen molar y de la refracción molar presentan variaciones lineales en función de la fracción molar de estearato de metilo. Los valores de viscosidad de las miscelas estudiadas se ajustan a la ecuación de fluidez de Hildebrand modificada, siendo su parámetro "V_o" función lineal de la fracción molar de estearato de metilo. En relación con estas tres características, el comportamiento de las miscelas estudiadas no difiere significativamente del correspondiente a una mezcla "ideal" de dos líquidos orgánicos sin ionizar.

Molar Uprighting: A Considerable and Safe Decision to Avoid Prosthetic Treatment

Science.gov (United States)

Raveli, Taísa Boamorte; Raveli, Dirceu Barnabé; de Mathias Almeida, Kelei Cristina; Pinto, Ary dos Santos

2017-01-01

Background: Tipped lower molar over edentulous space is very common in orthodontics practice when adults seek treatment. The segmented arch technique features a predictable force system that provides a controlled release of force that can produce light and continuous tooth movement. Case Description: A female adult patient, who lost a permanent lower first molar, needed correction of the position of her permanent first molar place. Instead of making space for rehabilitation, it was closed after second molar uprighting and a balanced interdigitation was created without prosthetics. The patient was successfully treated with segmented arch technique using root correction spring activated with geometry VI to promote uprighting of a tipped molar and Niti spring coil to promote space closure. Practical Implications: Segmented arch technique is known to provide predictable light and continuous forces, which is very much indicated in adult treatment. There are several things to consider when orthodontically treating adult patients. Their periodontal conditions might not be ideal, less bone apposition may occur, and side effects of orthodontic tooth movement are expected. Thus, a predictable and controlled orthodontic treatment is needed. PMID:29114332

Unilateral maxillary molar distalization with zygoma-gear appliance.

Science.gov (United States)

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

2012-08-01

The aim of this study was to present the orthodontic treatment of a 15-year-old boy with a unilateral maxillary molar distalization system, called the zygoma-gear appliance. It consisted of a zygomatic anchorage miniplate, an inner bow, and a Sentalloy closed coil spring (GAC International, Bohemia, NY). A distalizing force of 350 g was used during the distalization period. The unilateral Class II malocclusion was corrected in 5 months with the zygoma-gear appliance. The maxillary left first molar showed distalization of 4 mm with an inclination of 3°. The maxillary premolars moved distally with the help of the transseptal fibers. In addition, there were slight decreases in overjet (-0.5 mm) and maxillary incisor inclination (-1°), indicating no anchorage loss from the zygoma-gear appliance. Preadjusted fixed appliances (0.022 × 0.028-in, MBT system; 3M Unitek, Monrovia, Calif) were placed in both arches to achieve leveling and alignment. After 14 months of unilateral distalization with the zygoma-gear appliance and fixed appliances, Class I molar and canine relationships were established with satisfactory interdigitation of the posterior teeth. Acceptable overjet and overbite were also achieved. This article shows that this new system, the zygoma-gear appliance, can be used for unilateral maxillary molar distalization without anchorage loss. Copyright © 2012 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Estudio de mezclas de disolventes orgánicos y triglicéridos de aceite de linaza o los ácidos grasos libres. I.- Volumen molar, refracción molar y viscosidad dinámica

Directory of Open Access Journals (Sweden)

Mantell Serrano, C.

1995-06-01

Full Text Available Measurements of molar volume, refraction index and dynamic viscosity in mixtures of fatty acids or triglycerides and trichloroethylene, tetrachloroethylene and hexane were realized. Temperature range studied was 278-313 K each 5 K. The relationship between molar volume and molar fraction show high correlation coefficient In fatty acids with trichloroethylene and tetrachloroethylene mixtures. On the other hand, hexane mixtures show little contractions of molar volume at low molar fractions. Triglyceride mixtures present important deviations with regard to the ideality of the molar volume. The adjusts obtained for the molar volume values versus temperature are acceptable, calculating the coefficients of thermal expansion of the studied mixtures. Equally, the adjust of the experimental results of viscosity for two prediction equations are studied: one of additive type and the other of parabolic type.

Se han realizado medidas del volumen molar, índice de refracción y viscosidad dinámica en el intervalo de temperatura de 278 K a 313 K cada 5 K, a mezclas de ácidos grasos o triglicéridos con tricloroetileno, tetracloroetileno y hexano. Las mezclas de ácidos grasos con tricloroetileno y tetracloroetileno, presentan unos altos coeficientes de correlación para los valores del volumen molar frente a la fracción molar, mientras que las mezclas con hexano, a fracciones molares bajas, manifiestan una pequeña contracción del volumen molar. Las mezclas de triglicéridos presentan importantes desviaciones con respecto a la Idealidad del volumen molar. Los ajustes obtenidos para los valores del volumen molar frente a la temperatura son aceptables, determinándose los valores del coeficiente de dilatación volumétrica a presión constante de las mezclas estudiadas. Igualmente se ha estudiado el ajuste de los resultados experimentales de viscosidad a dos ecuaciones de predicción: una del tipo aditiva y otra del tipo parabólico.

Endodontic treatment of a maxillary second molar with developmental anomaly: a case report.

Science.gov (United States)

Asgary, Saeed

2007-01-01

Fusion is a rare occurrence in molar teeth. The purpose of this rare case presentation is to describe the nonsurgical endodontic treatment of maxillary molar. A 28-year-old patient was referred for endodontic treatment of her chronic apical abscess of right maxillary second molar. In the clinical examination, a sinus tract adjacent to involved tooth and a small crown of supernumerary tooth fused to the buccal surface of the molar at gingival margin was observed. Endodontic treatment was decided for the involved molar for functional reason. Recall examination, a year after completion of endodontic and restorative treatments, showed the tooth was clinically asymptomatic and there was no radiographic lucency around the apical region.

Occurrence of cervical invasive root resorption in first and second molar teeth of orthodontic patients eight years after bracket removal.

Science.gov (United States)

Thönen, Andrea; Peltomäki, Timo; Patcas, Raphael; Zehnder, Matthias

2013-01-01

The occurrence and potential orthodontic causes of cervical invasive root resorption (CIRR) are unknown. We aimed to identify the occurrence of CIRR in molar teeth of orthodontic patients treated with fixed appliances. All patients invited for final orthodontic recall between November 2009 and March 2011 were included. From 175 patients, 108 (46 men/62 women; mean age, 25 ± 5 years; mean time after bracket removal, 8 ± 2 years) were available. The first and second molar teeth (N = 858) of these patients were investigated for clinical and radiographic signs of CIRR. Patients identified with such signs were asked to have limited-volume cone-beam computed tomography scans performed. No clinical signs of CIRR were detected. CIRR could not be ruled out on bite-wing radiographs in 18 patients. CIRR was thus identified in 1 patient in whom a second maxillary molar was affected. All first molars had been extracted in this patient, and the second molars had been moved mesially over a long distance. The 3 other second molars showed surface resorption. CIRR in molar teeth of orthodontic patients have a low mid-term occurrence (0.9%; 95% confidence interval, 0.2%-5.2%). Long movement distances and/or long treatment duration may be related to the development of these lesions. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Patterns of third-molar agenesis and associated dental anomalies in an orthodontic population.

Science.gov (United States)

Celikoglu, Mevlut; Bayram, Mehmet; Nur, Metin

2011-12-01

The aim of this study was to investigate the frequency of dental anomalies in orthodontic patients with different patterns of third-molar agenesis, comparing them with patients without third-molar agenesis. A sample of 374 patients with agenesis of at least 1 third molar was divided into 4 groups according to the third-molar agenesis pattern, and a control group of 98 patients without third-molar agenesis was randomly selected from the patient archives. Panoramic radiographs and cast models were used to determine the associated dental anomalies, such as hypodontia, hyperdontia, impaction, dilaceration, microdontia, ectopic eruption, transposition, and transmigration. The Pearson chi-square and Fisher exact tests were used to determine the differences in the distribution of the associated dental anomalies among the groups. The prevalence of agenesis of other teeth (11.2%, n = 42) was significantly greater in our study sample (groups 1-4) than in the control group (group 5) (4.1%, n = 4; P dental anomalies in patients with agenesis of 3 and 4 third molars compared with the control group. Permanent tooth agenesis, microdontia of maxillary lateral incisors, and total dental anomalies are more frequently associated with agenesis of 4 third molars than with the presence of third molars. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Elongational viscosity of narrow molar mass distribution polystyrene

DEFF Research Database (Denmark)

Bach, Anders; Almdal, Kristoffer; Rasmussen, Henrik Koblitz

2003-01-01

Transient and steady elongational viscosity has been measured for two narrow molar mass distribution polystyrene melts of molar masses 200 000 and 390 000 by means of a filament stretching rheometer. Total Hencky strains of about five have been obtained. The transient elongational viscosity rises...... above the linear viscoelastic prediction at intermediate strains, indicating strain hardening. The steady elongational viscosities are monotone decreasing functions of elongation rate. At elongation rates larger than the inverse reptation time, the steady elongational viscosity scales linearly...

Endodontic Treatment of a Maxillary Second Molar with Developmental Anomaly: A Case Report

OpenAIRE

Asgary, Saeed

2007-01-01

Fusion is a rare occurrence in molar teeth. The purpose of this rare case presentation is to describe the nonsurgical endodontic treatment of maxillary molar. A 28-year-old patient was referred for endodontic treatment of her chronic apical abscess of right maxillary second molar. In the clinical examination, a sinus tract adjacent to involved tooth and a small crown of supernumerary tooth fused to the buccal surface of the molar at gingival margin was observed. Endodontic treatment was decid...

Standard molar enthalpies of formation of 2-, 3- and 4-cyanobenzoic acids

International Nuclear Information System (INIS)

Ribeiro da Silva, Manuel A.V.; Amaral, Luisa M.P.F.; Boaventura, Cristina R.P.; Gomes, Jose R.B.

2008-01-01

The standard (p 0 = 0.1 MPa) molar enthalpies of formation of 2-, 3- and 4-cyanobenzoic acids were derived from their standard molar energies of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The Calvet high temperature vacuum sublimation technique was used to measure the enthalpies of sublimation of 2- and 3-cyanobenzoic acids. The standard molar enthalpies of formation of the three compounds, in the gaseous phase, at T = 298.15 K, have been derived from the corresponding standard molar enthalpies of formation in the condensed phase and standard molar enthalpies for phase transition. The results obtained are -(150.7 ± 2.0) kJ . mol -1 , -(153.6 ± 1.7) kJ . mol -1 and -(157.1 ± 1.4) kJ . mol -1 for 2-cyano, 3-cyano and 4-cyanobenzoic acids, respectively. Standard molar enthalpies of formation were also estimated by employing two different methodologies: one based on the Cox scheme and the other one based on several different computational approaches. The calculated values show a good agreement with the experimental values obtained in this work

Effect of premature loss of deciduous canines and molars on malocclusion of the permanent dentition.

Science.gov (United States)

Miyamoto, W; Chung, C S; Yee, P K

1976-01-01

The effect of the premature loss of deciduous canines and first and second molars on malocclusion of the permanent dentition was studied in 255 schoolchildren 11 years of age or older at the most recent examination of the permanent dentition. Malocclusion was evaluated by scoring malalignment (major and minor) and measurement of crowding in the anterior teeth. Children who had a premature loss of one or more canines or molars had a higher frequency of receiving orthodontic treatment of one type or another for the permanent dentition. The likelihood of need of treatment increased with the number of prematurely lost teeth. Children who had lost one or more deciduous teeth through age 9 had a greater than threefold increase in the frequency of orthodontic treatment relative to the control. Of those who did not receive orthodontic treatment, there was no detectable relationship of the premature loss of canines with the malalignment of permanent teeth. However, there was a significant effect of the premature extraction of molars on malalignment especially major malalignment of permanent teeth. No differences were noted in their effects between the first and second deciduous molars. Crowding of the anterior teeth was directly affected by the premature loss of deciduous canines.

C-shaped root canal in a maxillary first molar: a case report.

Science.gov (United States)

Yilmaz, Z; Tuncel, B; Serper, A; Calt, S

2006-02-01

This case report presents an unusual C-shaped root canal system in a maxillary first molar tooth. Although C-shaped root canals are most frequently seen in the mandibular second molar, they may also appear in maxillary molars. A literature search revealed only a few case reports of C-shaped root canal systems in maxillary molars. The present case describes a C-shaped canal in the buccal root of a maxillary first molar. The endodontic access cavity displayed two canal orifices, one leading to the canal system in the buccal root, the other into the palatal root canal system. In the buccal root, what appeared to be the mesial and distal canals joined to form a single C-shaped canal. --Careful examination of radiographs and the internal anatomy of teeth is essential.-- The location and morphology of root canals should be identified at high magnification under the microscope.

Use of palatally inserted mini-screw for upper molar distalization: A case series

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Valliollah Arash

2015-09-01

Full Text Available  Abstract Reports have shown that molars can be distalized successfully with virtually no orthodontic anchorage loss with an intraosseous anchorage, even with fully erupted second molars. The purpose of this study was evaluating the effects of mini-screws as skeletal anchorage for upper molar distalization. In this case series, three patients needing maxillary first molar distalization, were selected. mini-screw was inserted in the anterior part of the palate. The screws were anchored to the first premolars by transpalatal arch and immediately loaded (150-160 g by 0.018-inch arch-wire and steel open-coil spring to distalize maxillary molars. The skeletal and dental changes were measured on cephalograms obtained before and after distalization. The amount of first molar distalization in the patients was 4 mm with 2°of tipping, 4 mm with 5°of tipping, and 3.5 mm with 2°of tipping respectively. Upper incisors and first premolars were stable during distalization.       

Molar incisor hypomineralisation: clinical management of the young patient.

LENUS (Irish Health Repository)

Daly, Dympna

2009-04-01

Molar incisor hypomineralisation (MIH) is a common developmental condition resulting in enamel defects in first permanent molars and permanent incisors. It presents at eruption of these teeth. Early diagnosis is essential since rapid breakdown of tooth structure may occur, giving rise to acute symptoms and complicated treatment. The purpose of this article is to review MIH and illustrate its clinical management in young children.

Branched-chain amino acids to tyrosine ratio value as a potential prognostic factor for hepatocellular carcinoma.

Science.gov (United States)

Ishikawa, Toru

2012-05-07

The prognosis of hepatocellular carcinoma (HCC) depends on tumor extension as well as hepatic function. Hepatic functional reserve is recognized as a factor affecting survival in the treatment of HCC; the Child-Pugh classification system is the most extensively used method for assessing hepatic functional reserve in patients with chronic liver disease, using serum albumin level to achieve accurate assessment of the status of protein metabolism. However, insufficient attention has been given to the status of amino acid (AA) metabolism in chronic liver disease and HCC. Fischer's ratio is the molar ratio of branched-chain AAs (BCAAs: leucine, valine, isoleucine) to aromatic AAs (phenylalanine, tyrosine) and is important for assessing liver metabolism, hepatic functional reserve and the severity of liver dysfunction. Although this ratio is difficult to determine in clinical situations, BCAAs/tyrosine molar concentration ratio (BTR) has been proposed as a simpler substitute. BTR correlates with various liver function examinations, including markers of hepatic fibrosis, hepatic blood flow and hepatocyte function, and can thus be considered as reflecting the degree of hepatic impairment. This manuscript examines the literature to clarify whether BTR can serve as a prognostic factor for treatment of HCC.

MMP20 Overexpression Disrupts Molar Ameloblast Polarity and Migration.

Science.gov (United States)

Shin, M; Chavez, M B; Ikeda, A; Foster, B L; Bartlett, J D

2018-02-01

Ameloblasts responsible for enamel formation express matrix metalloproteinase 20 (MMP20), an enzyme that cleaves enamel matrix proteins, including amelogenin (AMELX) and ameloblastin (AMBN). Previously, we showed that continuously erupting incisors from transgenic mice overexpressing active MMP20 had a massive cell infiltrate present within their enamel space, leading to enamel mineralization defects. However, effects of MMP20 overexpression on mouse molars were not analyzed, although these teeth more accurately represent human odontogenesis. Therefore, MMP20-overexpressing mice ( Mmp20 +/+ Tg + ) were assessed by multiscale analyses, combining several approaches from high-resolution micro-computed tomography to enamel organ immunoblots. During the secretory stage at postnatal day 6 (P6), Mmp20 +/+ Tg + mice had a discontinuous ameloblast layer and, unlike incisors, molar P12 maturation stage ameloblasts abnormally migrated away from the enamel layer into the stratum intermedium/stellate reticulum. TOPflash assays performed in vitro demonstrated that MMP20 expression promoted β-catenin nuclear localization and that MMP20 expression promoted invasion through Matrigel-coated filters. However, for both assays, significant differences were eliminated in the presence of the β-catenin inhibitor ICG-001. This suggests that MMP20 activity promotes cell migration via the Wnt pathway. In vivo, the unique molar migration of amelogenin-expressing ameloblasts was associated with abnormal deposition of ectopic calcified nodules surrounding the adherent enamel layer. Enamel content was assessed just prior to eruption at P15. Compared to wild-type, Mmp20 +/+ Tg + molars exhibited significant reductions in enamel thickness (70%), volume (60%), and mineral density (40%), and MMP20 overexpression resulted in premature cleavage of AMBN, which likely contributed to the severe defects in enamel mineralization. In addition, Mmp20 +/+ Tg + mouse molar enamel organs had increased levels

Space loss following premature loss of primary second molars.

Science.gov (United States)

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

2015-01-01

This study was designed to evaluate the amount of space loss (SL) caused by premature loss of primary second molars, determine whether the eruption status of permanent first molars is an important factor in the amount of SL, and evaluate the effectiveness of space maintainers (SMs) in SL prevention. SL associated with 100 prematurely extracted primary second molars was evaluated in 87 healthy patients. Teeth were divided into groups based on the use of SMs (36 with SM and 64 without SM). Bitewing and periapical radiographs taken before extraction and 6, 12, 24, 36, and 48 months after extraction were used to determine the amount of SL. Not every patient attended every recall appointment, so the sample size varied at different evaluation times. The most significant amount of SL occurred in the first 12 months after extraction. In patients who did not use an SM, at 6 months there was a mean SL of 2.12 mm (SD, 1.65 mm) and at 12 months there was a mean of 4.02 mm (SD, 1.65), with significantly more SL in the first 6 months (P 0.05). When patients without an SM were grouped by the eruption status of the permanent first molar, there was significantly more SL in the groups with unerupted first molars than there was in the groups with erupted first molars at both 6 months (P < 0.001) and 12 months (P < 0.05). At both 6 and 12 months, the amount of SL in patients who had an SM (n = 13 and n = 14, respectively) was not significantly different from the amount of SL in those who did not have an SM (n = 33 and n = 23, respectively). SMs should be placed as soon as possible following tooth extraction to prevent undue SL. Placement of an SM a year or more after extraction has minimal benefit, since most SL takes place within the first year. SL does occur even when SMs are used.

A combined experimental and computational investigation of excess molar enthalpies of (nitrobenzene + alkanol) mixtures

International Nuclear Information System (INIS)

Neyband, Razieh Sadat; Zarei, Hosseinali

2015-01-01

Highlights: • Excess molar enthalpies for the binary mixtures of nitrobenzene + alkanols mixtures were measured. • The infinite dilution excess partial molar enthalpies were calculated using the ab initio methods. • The PCM calculations were performed. • The computed excess partial molar enthalpies at infinite dilution were compared to experimental results. - Abstract: Excess molar enthalpies (H m E ) for the binary mixtures of {(nitrobenzene + ethanol), 1-propanol, 2-propanol, 1-butanol and 2-butanol} have been measured over the entire composition range at ambient pressure (81.5 kPa) and temperature 298 K using a Parr 1455 solution calorimeter. From the experimental results, the excess partial molar enthalpies (H i E ) and excess partial molar enthalpies at infinite dilution (H i E,∞ ) were calculated. The excess molar enthalpies (H m E ) are positive for all {nitrobenzene (1) + alkanol (2)} mixtures over the entire composition range. A state-of-the-art computational strategy for the evaluation of excess partial molar enthalpies at infinite dilution was followed at the M05-2X/6-311++G ∗∗ level of theory with the PCM model. The experimental excess partial molar enthalpies at infinite dilution have been compared to the computational data of the ab initio in liquid phase. Integrated experimental and computational results help to clarify the nature of the intermolecular interactions in {nitrobenzene (1) + alkanol (2)} mixtures. The experimental and computational work which was done in this study complements and extends the general research on the computation of excess partial molar enthalpy at infinite dilution of binary mixtures

Odor concentration invariance by chemical ratio coding

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Naoshige Uchida

2008-08-01

Full Text Available Many animal species rely on chemical signals to extract ecologically important information from the environment. Yet in natural conditions chemical signals will frequently undergo concentration changes that produce differences in both level and pattern of activation of olfactory receptor neurons. Thus, a central problem in olfactory processing is how the system is able to recognize the same stimulus across different concentrations. To signal species identity for mate recognition, some insects use the ratio of two components in a binary chemical mixture to produce a code that is invariant to dilution. Here, using psychophysical methods, we show that rats also classify binary odor mixtures according to the molar ratios of their components, spontaneously generalizing over at least a tenfold concentration range. These results indicate that extracting chemical ratio information is not restricted to pheromone signaling and suggest a general solution for concentration-invariant odor recognition by the mammalian olfactory system.

Roentgenographic studies on the growth and development of lower third molars in Korean female

Energy Technology Data Exchange (ETDEWEB)

Lim, Hyoung Soon; Lee, Sung Woo [Department of Dental Radiology, College of Dentistry, Seoul National University, Seoul (Korea, Republic of)

1976-11-15

The author obtained the following results through the studies on 1012 roentgenograms of lower third molar regions of Korean female; 1. The rate of presence of lower third molars was 78.9 percent. 2. The period that crowns of lower third molars become completed was 16.1 years. 3. The period that completion of apices of lower third molars become completed was over 27 years.

Molar Volume Analysis of Molten Ni-Al-Co Alloy by Measuring the Density

Institute of Scientific and Technical Information of China (English)

XIAO Feng; FANG Liang; FU Yuechao; YANG Lingchuan

2004-01-01

The density of molten Ni-Al-Co alloys was measured in the temperature range of 1714～1873K using a modified pycnometric method, and the molar volume of molten alloys was analyzed. The density of molten Ni-Al-Co alloys was found to decrease with increasing temperature and Co concentration in alloys. The molar volume of molten Ni-Al-Co alloys increases with increasing Co concentration in alloys. The molar volume of molten Ni-Al-Co alloys shows a negative deviation from the linear molar volume.

Maxillary First Molars with 2 Distobuccal Canals: A Case Series.

Science.gov (United States)

Fogel, Howard M; Cunha, Rodrigo Sanches

2017-11-01

An appreciation of the anatomic complexity of the root canal system is essential at every step of endodontic treatment. Endodontic treatment of teeth with unusual root canal anatomy presents a unique challenge. Eight patients underwent nonsurgical root canal treatment of 3-rooted maxillary first molars in a specialty endodontic private practice. Four cases of Weine type II and 4 cases of Weine type III canal configurations in the distobuccal root of maxillary first molars were presented.This article highlighted an uncommon anatomic variation of 2 canals in the distobuccal root of the maxillary first molar. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

C-reactive protein a better indicator of inflammation after third molar ...

African Journals Online (AJOL)

operative pain and pre-operative levels of C-reactive and post-operative pain and swelling in impacted third molar surgery. Materials and Methods: In this prospective study subjects were patients indicated for mandibular third molar extraction.

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

Science.gov (United States)

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

2015-09-01

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

Two-rooted maxillary first molars with two canals: a case series.

Science.gov (United States)

Shakouie, Sahar; Mokhtari, Hadi; Ghasemi, Negin; Gholizadeh, Seddigheh

2013-01-01

Thorough understanding of the anatomic and internal morphology of a root canal system is absolutely essential for the success of endodontic treatment. Since permanent maxillary first molars have shown variation in internal anatomy, morphology, this tooth has been reviewed extensively. Presence of two canals in a two-rooted maxillary first molar has rarely been reported in studies describing tooth and root canal anatomies. In this report, three cases are presented, which involve the root canal treatment of maxillary first molars with fusion of the two buccal roots.

Morphology of the Physiological Apical Foramen in Maxillary and Mandibular First Molars.

Science.gov (United States)

Abarca, J; Zaror, C; Monardes, H; Hermosilla, V; Muñoz, C; Cantin, M

2014-06-01

Information regarding the anatomy of the physiological apical foramen is limited. Knowing its diameter and shapes contributes to clinical work, specifically to the cleaning and shaping of the apical third. The aim of this ex vivo study was to determine the minimum and maximum diameters and shape of the physiological apical foramen in the roots of maxillary and mandibular first molars. A descriptive study was conducted on 89 recently extracted first molars. Roots 3-5 mm from the apex were sectioned and prepared for analysis at 40× magnification. The minimum and maximum diameters of each physiological foramen were measured using the program Motic Images plus 2.0 ML. The shape of the foramina, classified as round, oval or irregular, was determined by the difference between the maximum and minimum diameters. A total of 174 physiological foramina were analyzed. The average of the minimum and maximum diameters was between 0.24-0.33 mm in maxillary first molars and between 0.25-0.33 mm in mandibular first molars. In maxillary molars, the most common shape of the foramen was oval (50%), then irregular (32%), then round (18%). In mandibular molars, the oval shape was also the most frequent (59%), followed by irregular (23%) and round (18%). The findings of this study regarding the morphology of physiological apical foramina in first molars make it easier for the operator to choose the appropriately-sized instruments to perform endodontic therapy successfully.

Morphology of the Physiological Apical Foramen in Maxillary and Mandibular First Molars

Science.gov (United States)

Abarca, J.; Zaror, C.; Monardes, H.; Hermosilla, V.; Muñoz, C.; Cantin, M.

2015-01-01

SUMMARY Information regarding the anatomy of the physiological apical foramen is limited. Knowing its diameter and shapes contributes to clinical work, specifically to the cleaning and shaping of the apical third. The aim of this ex vivo study was to determine the minimum and maximum diameters and shape of the physiological apical foramen in the roots of maxillary and mandibular first molars. A descriptive study was conducted on 89 recently extracted first molars. Roots 3–5 mm from the apex were sectioned and prepared for analysis at 40× magnification. The minimum and maximum diameters of each physiological foramen were measured using the program Motic Images plus 2.0 ML. The shape of the foramina, classified as round, oval or irregular, was determined by the difference between the maximum and minimum diameters. A total of 174 physiological foramina were analyzed. The average of the minimum and maximum diameters was between 0.24–0.33 mm in maxillary first molars and between 0.25–0.33 mm in mandibular first molars. In maxillary molars, the most common shape of the foramen was oval (50%), then irregular (32%), then round (18%). In mandibular molars, the oval shape was also the most frequent (59%), followed by irregular (23%) and round (18%). The findings of this study regarding the morphology of physiological apical foramina in first molars make it easier for the operator to choose the appropriately-sized instruments to perform endodontic therapy successfully. PMID:25937698

Apparent molar volumes, isobaric expansion coefficients, and isentropic compressibilities, and their H/D isotope effects for some aqueous carbohydrate solutions

International Nuclear Information System (INIS)

Bernal, P.J.; Van Hook, W.A.

1986-01-01

The molar volumes, isobaric expansion coefficients, and isentropic compressibilities of solutions of a number of carbohydrates and their deuterated isomers were determined in H 2 O and D 2 O between 288.15 and 328.15 K and over a wide range of solute-to-solvent mole ratios. The results are discussed in terms of the specific hydration model. (author)

Ratio of critical quantities related to Hawking temperature–entanglement entropy criticality

Directory of Open Access Journals (Sweden)

Jie-Xiong Mo

2017-10-01

Full Text Available We revisit the Hawking temperature–entanglement entropy criticality of the d-dimensional charged AdS black hole with our attention concentrated on the ratio TcδSEcQc. Comparing the results of this paper with those of the ratio TcScQc, one can find both the similarities and differences. These two ratios are independent of the characteristic length scale l and dependent on the dimension d. These similarities further enhance the relation between the entanglement entropy and the Bekenstein–Hawking entropy. However, the ratio TcδSEcQc also relies on the size of the spherical entangling region. Moreover, these two ratios take different values even under the same choices of parameters. The differences between these two ratios can be attributed to the peculiar property of the entanglement entropy since the research in this paper is far from the regime where the behavior of the entanglement entropy is dominated by the thermal entropy.

Histopathologic Evaluation of Follicular Tissues Associated with Impacted Third Molars

Directory of Open Access Journals (Sweden)

M. Khorasani

2008-06-01

Full Text Available Objective: The aim of the present study was to histopathologically evaluate follicular tissues of third molars with pericoronal radiolucenciesof less than 2 millimeters.Materials and Methods: In this descriptive analytic study, 100 impacted third molars with normal follicular spaces were removed and their pericoronaltissues submitted for histopathologic examination. Different characteristicsof the epithelium and connective tissue were evaluated in all cases. Statisti-cal analysis was performed using chi square and Mann-Whitney tests.Results: In our study sample, 74% of the patients were female and 26% were male, ranging in age from 13 to 54 years (mean, 25.3 years. Lining epithelium was observed in 69% of the specimens of which 31%, 23% and 14% was cuboidal, squamous and columnar, respectively. A significant re-lationship was found between the presence of squamous epithelium and pa-tient age (P<0.05. Nonspecific chronic inflammation was the only patho-logic finding observed in 44% of the specimens. Inflammation was signifi-cantly associated with age and squamous metaplasia (P<0.05.Conclusion: Considering that pathologic lesions were not observed in anyof the studied cases, unerupted third molars should not be removed unless there is a clinical indication to do so, or in case the impacted molar shows evidence of pathological changes. Follow-up is suggested for asympto-matic impacted third molars.

Standard molar enthalpies of formation of 2-, 3-, and 4-piperidinomethanol isomers

International Nuclear Information System (INIS)

Ribeiro da Silva, Manuel A.V.; Cabral, Joana I.T.A.

2006-01-01

The standard (p o =0.1MPa) molar energies of combustion in oxygen of 2-piperidinemethanol, 3-piperidinemethanol, and 4-piperidinemethanol, all in the crystalline phase, were measured, at T=298.15K, by static bomb calorimetry. These values were used to derive the standard molar enthalpies of combustion and the standard molar enthalpies of formation, in the condensed phase, for these compounds. Further, the standard molar enthalpies of sublimation, at T=298.15K, of these three piperidinomethanol isomers were determined by Cavet microcalorimetry. The combustion calorimetry results together with those from the Calvet microcalorimetry, were used to derive the standard molar enthalpies of formation, at T=298.15K, in the gaseous phase, of the three piperidinemethanol studied. -Δ c H m o (cr)Δ cr g H m o kJ.mol -1 kJ.mol -1 2-Piperidinemethanol3890.70+/-0.9293.02+/-0.503- Piperidinemethanol3895.3+/-1.195.9+/-1.44-Piperidinemethanol3891.3+/- 1.198.31+/-0.69

In vitro evaluation of an alternative method to bond molar tubes

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Célia Regina Maio Pinzan-Vercelino

2011-02-01

Full Text Available Despite the advances in bonding materials, many clinicians today still prefer to place bands on molar teeth. Molar bonding procedures need improvement to be widely accepted clinically. OBJECTIVE: The purpose of this study was to evaluate the shear bond strength when an additional adhesive layer was applied on the occlusal tooth/tube interface to provide reinforcement to molar tubes. MATERIAL AND METHODS: Sixty third molars were selected and allocated to the 3 groups: group 1 received a conventional direct bond followed by the application of an additional layer of adhesive on the occlusal tooth/tube interface, group 2 received a conventional direct bond, and group 3 received a conventional direct bond and an additional cure time of 10 s. The specimens were debonded in a universal testing machine. The results were analyzed statistically by ANOVA and Tukey's test (α=0.05. RESULTS: Group 1 had a significantly higher (p0.05. CONCLUSIONS: The present in vitro findings indicate that the application of an additional layer of adhesive on the tooth/tube interface increased the shear bond strength of the bonded molar tubes.

Variant root morphology of third mandibular molar in normal and ...

African Journals Online (AJOL)

The mandibular third molar poses a challenge to dental surgeons due to it's unpredictable morphology which leads to increased difficulty during its extraction. The root morphology of the third molar is considered to be the most variable in the human dentition. The study aims to document these variations which will be useful ...

Management of periodontally compromised mandibular molar with Hemisectioning: A case report

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Bandu Napte

2014-01-01

Full Text Available Introduction: Hemisection involves sectioning of a periodontally involved mandibular molar so as to remove the involved root and save the remaining tooth. This procedure helps in saving a tooth which otherwise would have been deemed for extraction. Hemisection refers to removal or separation of root with its accompanying crown portion of two-rooted teeth, most commonly mandibular molars. Method: In this case report, an advanced Endo-Perio lesion on a left mandibular first molar was successfully treated by root-canal treatment and hemisection. This procedure helps preserve the tooth structure, alveolar bone and promote cost savings over other treatment options. Conclusion: Hemisection is a treatment option for saving a mandibular molar which is in advanced stage of periodontal disease of one root. Removal of the affected root will help in retaining the remaining tooth structure.

Molar incisor hypomineralization: Considerations about treatment in a controlled longitudinal case

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Daniela Cristina de Oliveira

2015-01-01

Full Text Available Molar incisor hypomineralization (MIH is a defect in the tooth enamel of systemic origin and may affect one or all four first permanent molars frequently associated with the permanent incisors. This case reports a 7-year-old child with severe MIH in the permanent molars associated with tooth decay and intense pain. In the first stage of treatment, therapy was performed with fluoride varnish and restoration with glass ionomer cement (GIC. After 6 years of clinical and radiographic follow-up, the restorations presented wear and fractures on the margins, indicating their replacement with composite resin. Severe cases of MIH in the early permanent molars can be treated with varnish and GIC to restore the patient′s comfort and strengthen the hypomineralized dental structures. The clinical and radiographic monitoring frequently indicated when the restoration with composite resin should be performed.

Approximal morphology as predictor of approximal caries in primary molar teeth

DEFF Research Database (Denmark)

Cortes, A; Martignon, S; Qvist, V

2018-01-01

consent was given, participated. Upper and lower molar teeth of one randomly selected side received a 2-day temporarily separation. Bitewing radiographs and silicone impressions of interproximal area (IPA) were obtained. One-year procedures were repeated in 52 children (84%). The morphology of the distal...... surfaces of the first molar teeth and the mesial surfaces on the second molar teeth (n=208) was scored from the occlusal aspect on images from the baseline resin models resulting in four IPA variants: concave-concave; concave-convex; convex-concave, and convex-convex. Approximal caries on the surface...

Prevalence and Pattern of Third Molar Impaction; A retrospective study of radiographs in Oman

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Samira M. Al-Anqudi

2014-08-01

Full Text Available Objectives: The aim of this retrospective study was to investigate the prevalence and pattern of third molar impaction in patients between 19‒26 years old attending Sultan Qaboos University Hospital (SQUH in Muscat, Oman. Methods: The study reviewed 1,000 orthopantomograms (OPGs of patients attending the Oral Health Department of SQUH between October 2010 and April 2011. Patients were evaluated to determine the prevalence of third molar impaction, angulation, level of eruption and associated pathological conditions. Results: Of the study population, 543 (54.3% OPGs showed at least one impacted third molar. The total number of impacted molars was 1,128. The most common number of impacted third molars was two (41%. The most common angulation of impaction in the mandible was the mesioangular (35% and the most common level of impaction in the mandible was level A. Of the 388 bilateral occurrences of impacted third molars, 377 were in the mandible. There was no significant difference in the frequency of impaction between the right and left sides of both jaws. Pathological conditions associated with impacted lower third molars were found in 18%, of which 14% were associated with a radiographic radiolucency of more than 2.5 mm, and 4% of impacted lower third molars were associated with dental caries. Conclusion: This study found that more than half of Omani adult patients ranging in age from 19‒26 years had at least one impacted third molar.

Dental and skeletal changes after intraoral molar distalization with sectional jig assembly.

Science.gov (United States)

Gulati, S; Kharbanda, O P; Parkash, H

1998-09-01

The present study was conducted on 10 subjects to evaluate dental and skeletal changes after intraoral molar distalization. The maxillary molars were distalized with a sectional jig assembly. Sentalloy open coil springs were used to exert 150 gm of force for a period of 12 weeks. A modified Nance appliance was the main source of anchorage. The pre- and postdistalization records included dental study casts, clinical photographs, and cephalograms. A total of 665 readings recorded from lateral cephalograms and dental casts were subjected to statistical analysis. The mean distal movement of the first molar was 2.78 mm, which was highly significant (o < 0.001). It moved distally at the rate of 0.86 mm/month. There was clinically some distal tipping (3.50 degrees) and distopalatal rotation (2.40 degrees). These changes were statistically significant (p < 0.001). The second molars accompanied the first molars and moved distally by nearly the same amount. There was 1.00 mm increase in the overjet and 2.60 degrees mesial tip of second premolar. The changes in the facial skeleton and dentition bases were minimal and statistically not significant. However, there was clockwise rotation of the mandible of 1.30 degrees that was statistically significant. This was the result of molar extrusion (1.60 mm).

Psychological impact of third molar surgery: a 1-month prospective study

NARCIS (Netherlands)

de Jongh, Ad; van Wijk, Arjen J.; Lindeboom, Jerome A.

2011-01-01

To prospectively examine the psychological impact of surgical third molar removal, and to identify possible psychological risk factors for the development of dental anxiety and symptoms of psychological trauma. Patients (N = 71) scheduled for surgical mandibular third molar removal were assessed

Trace element profiles in modern horse molar enamel as tracers of seasonality: Evidence from micro-XRF, LA-ICP-MS and stable isotope analysis

Science.gov (United States)

de Winter, Niels; Goderis, Steven; van Malderen, Stijn; Vanhaecke, Frank; Claeys, Philippe

2016-04-01

A combination of laboratory micro-X-ray Fluorescence (μXRF) and stable carbon and oxygen isotope analysis shows that trace element profiles from modern horse molars reveal a seasonal pattern that co-varies with seasonality in the oxygen isotope records of enamel carbonate from the same teeth. A combination of six cheek teeth (premolars and molars) from the same individual yields a seasonal isotope and trace element record of approximately three years recorded during the growth of the molars. This record shows that reproducible measurements of various trace element ratios (e.g., Sr/Ca, Zn/Ca, Fe/Ca, K/Ca and S/Ca) lag the seasonal pattern in oxygen isotope records by 2-3 months. Laser Ablation-ICP-Mass Spectrometry (LA-ICP-MS) analysis on a cross-section of the first molar of the same individual is compared to the bench-top tube-excitation μXRF results to test the robustness of the measurements and to compare both methods. Furthermore, trace element (e.g. Sr, Zn, Mg & Ba) profiles perpendicular to the growth direction of the same tooth, as well as profiles parallel to the growth direction are measured with LA-ICP-MS and μXRF to study the internal distribution of trace element ratios in two dimensions. Results of this extensive complementary line-scanning procedure shows the robustness of state of the art laboratory micro-XRF scanning for the measurement of trace elements in bioapatite. The comparison highlights the advantages and disadvantages of both methods for trace element analysis and illustrates their complementarity. Results of internal variation within the teeth shed light on the origins of trace elements in mammal teeth and their potential use for paleo-environmental reconstruction.

Study of pulp chamber morphology of primary mandibular molars using spiral computed tomography.

Science.gov (United States)

Selvakumar, Haridoss; Kavitha, Swaminathan; Vijayakumar, Rajendran; Eapen, Thomas; Bharathan, Rajendran

2014-11-01

The purpose of this study was to evaluate the pulp chamber morphology in primary mandibular molars using spiral computed tomography (SCT). Sixty extracted primary mandibular molars were scanned using SCT for the (i) distance between the central fissure to furcation, (ii) distance between the central fissure to the floor of the pulp chamber, (iii) height of the pulp chamber (roof-floor), (iv) distance between the floor of the pulp chamber to the furcation. The mean and standard deviation was analyzed using statistical package for the social sciences (SPSS) program. The results of this study show that the average mean distance from the central fissure to the floor of the pulp chamber is 5.07 mm in first mandibular primary molar and 5.54 mm in second mandibular primary molar. It can be concluded that the greatest depth to which a bur can go during access opening without perforating the furcation in first primary mandibular molar is 5.07 mm and 5.54 mm in second primary mandibular molar.

Temporal abscess after third molar extraction in the mandible.

Science.gov (United States)

de Oliveira Neto, Patrício José; de Souza Maliska, Maximiana Cristina; Sawazaki, Renato; Asprino, Luciana; de Moraes, Márcio; Moreira, Roger William Fernandes

2012-03-01

Dental infections resulting before or after third molar removal are complications in which the maxillofacial surgeon may have to initiate an earlier management. The severe dental infections resulting before or after this procedure is one of the few life-threatening complications in which the maxillofacial surgeon may have to initiate an earlier management. Infections involving the temporal space are rare and infrequently reported. Infections in this space have also been observed secondary to maxillary sinusitis, maxillary sinus fracture, temporomandibular arthroscopy, and drug injection, although more commonly associated to third molar infections. A 22-year-old man had undergone extraction of tooth 38 secondary to pericoronaritis by a general dentist. Physical examination of his face demonstrated severe trismus, pain, and swelling in temporal region. A CT scan showed an inflammatory area into the temporal space. He was started on IV cephalosporin, but the clinical course of the patient was not satisfactory. Incision and drainage were performed from an extraoral and intraoral approach. After discharged, the antibiotic was switched to clindamycin IO 600 mg. The retromaxillary and temporal infections are quite common after maxillary molar extractions but not after mandibular third molar, the spread mechanism of ascension must be involved with the virulence of microorganisms, but more studies are necessary to clarify this occurrence.

X-RAY MEASUREMENTS OF IMPACTED MANDIBULAR THIRD MOLARS

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Petya G. Kanazirska

2017-03-01

Full Text Available The X-ray diagnostics is essential in case of retention of teeth. An important condition for proper treatment plan for impacted third molars of the mandible is the determination of the type of retention in the jaw in accordance with their medio-distal inclination and the space available for eruption (retromolar space. Purpose: The purpose of this article is to present an objective method for determination of the medio-distal inclination and the space for eruption of the third molars of the mandible. Materials and methods: The studied patients with impacted third molars of the mandible are 127, aged 17 through 60. They were examined with Cone-beam Computed Tomography (CBCT. On the orthopantomography, obtained after the scanning as a reconstructed image, we defined the medio-distal inclination and space for eruption of the third molars of the mandible. For this purpose, we summarized several methods. Results: The most common inclination of the third molars of the mandible with retained eruption is the medial one at 120 teeth (61.5% ± 3.5. Second in frequency is the vertical one-34 teeth (17.4% ± 2.7, followed by the distal inclination– 21 teeth (10.8% ± 2.2. With the lowest frequency are the teeth which are positioned horizontally –20 teeth (10.3% ± 2.2. Shortage of retromolar space is established for173 teeth (88.7% ± 2.3. In 22 teeth (11.3% ± 2.3 there is enough space in the jaw for eruption. Conclusion: An objective method for determination of the medio-distal inclination of the teeth and the space available for eruption is introduced for the first time in Bulgaria. By determining the inclination of impacted wisdom teeth under this methodology one can avoid the subjective factor–the seventh tooth. It is not a reference plane, because it can also be tilted or missing. With the help of the developed method the retromolar point can be determined more objectively.

Relationship between fracture of mandibular condyle and absence of unerupted mandibular third molar-a retrospective study.

Science.gov (United States)

Rajan, Ritesh; Verma, Dinesh Kumar; Borle, R M; Yadav, Abhilasha

2016-06-01

The purpose of the present study was to find, if there exists, a co-relation between presence of unerupted mandibular third molar and fracture of mandibular condyle. A retrospective, multicenter study was done collecting the data of all mandibular condyle fractures treated from November 2006 till August 2015. Data was collected from the patient's records and radiographs for the following information: age, sex, etiology of fracture, presence and state of lower third molars, and associated fracture. The results were subjected to statistical analysis. Out of 180 patients of condylar fracture, unerupted third molars were present in 35 (19.44 %) cases compared to 145 (80.55 %) cases of condylar fracture where the unerupted third molars were not present. The difference was statistically significant (p fracture was seen in 4 (11.4 %) cases, bilateral condylar fracture associated with other mandibular fractures in 9 (25.7 %) cases, isolated unilateral condylar fracture in 0 (0.0 %) cases, and unilateral condylar fracture associated with other mandibular fractures in 17 (48.5 %) cases and condylar fracture associated with mid face fractures in 5 (14.2 %) cases. In the unerupted third molar absent group, isolated bilateral condylar fracture was seen in 5 (3.4 %) cases, bilateral condylar fracture associated with other mandibular fractures in 30 (20.6 %) cases, isolated unilateral condylar fracture in 24 (16.5 %) cases, unilateral condylar fracture associated with other mandibular fractures in 73 (50.34 %) cases, and condylar fracture associated with mid face fractures in 13(8.96 %) cases. The difference between the groups was statistically significant (p = 0.032). This study suggests that the fractures of mandibular condylar region have a significantly higher incidence in patients without an unerupted mandibular third molar.

Age assessment based on third molar mineralisation : An epidemiological-radiological study on a Central-European population.

Science.gov (United States)

Hofmann, Elisabeth; Robold, Matthias; Proff, Peter; Kirschneck, Christian

2017-03-01

The method published in 1973 by Demirjian et al. to assess age based on the mineralisation stage of permanent teeth is standard practice in forensic and orthodontic diagnostics. From age 14 onwards, however, this method is only applicable to third molars. No current epidemiological data on third molar mineralisation are available for Caucasian Central-Europeans. Thus, a method for assessing age in this population based on third molar mineralisation is presented, taking into account possible topographic and gender-specific differences. The study included 486 Caucasian Central-European orthodontic patients (9-24 years) with unaffected dental development. In an anonymized, randomized, and blinded manner, one orthopantomogram of each patient at either start, mid or end of treatment was visually analysed regarding the mineralisation stage of the third molars according to the method by Demirjian et al. Corresponding topographic and gender-specific point scores were determined and added to form a dental maturity score. Prediction equations for age assessment were derived by linear regression analysis with chronological age and checked for reliability within the study population. Mineralisation of the lower third molars was slower than mineralisation of the upper third molars, whereas no jaw-side-specific differences were detected. Gender-specific differences were relatively small, but girls reached mineralisation stage C earlier than boys, whereas boys showed an accelerated mineralisation between the ages of 15 and 16. The global equation generated by regression analysis (age = -1.103 + 0.268 × dental maturity score 18 + 28 + 38 + 48) is sufficiently accurate and reliable for clinical use. Age assessment only based on either maxilla or mandible also shows good prognostic reliability.

Using cone beam computed thomography in planning the extraction of impacted third molars

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Vlahović Zoran

2016-01-01

Full Text Available The panoramic radiography is the most used diagnostic imaging method in planning impacted lower third molar extractions. However, often panoramic radiography does not provide enough information in treatment planning for performing safely surgical extraction of impacted third molars. CBCT (Cone beam computed tomography provides more precise information in diagnostic analysis especially for planning surgical procedures where complications can be expected due to close relationship between mandibular canal and lower impacted third molars. The aim of this study is comparative analysis of panoramic radiography and CBCT in evaluating the topographic relationship between mandibular canal and impacted third molars. The study included 50 patients with close relationship between mandibular canal and impacted third molars detected using panoramic radiography. After panoramic radiography analysis CBCT was performed in order to diagnose, plan and prevent complications during the surgical tooth extraction. CBCT examination considered comparative analysis with panoramic radiography, marking, volume rendering and assessment of mandibular canal in buccolingual direction. Out of total patients where suprimposition of mandibular canal and impacted third molar on panoramic radiography was detected, in 32 patients mandibular chanal was localised on lingual side. Mandibular canal was positioned at bucal side in 18 of 50 patients. Results of this research indicate that panoramic radiography can be useful in everyday practice for diagnosis, planning and preparing lower third molar extractions, but in cases where close relationship between mandibular canal and lower third molars is detected CBCT is recommended as more precise radiographic imaging method in order to prevent complications.

Subcutaneous emphysema during third molar surgery: a case report

OpenAIRE

Romeo, Umberto; Galanakis, Alexandros; Lerario, Francesco; Daniele, Gabriele Maria; Tenore, Gianluca; Palaia, Gaspare

2011-01-01

Extraction of third molars is the most common surgical procedure performed in oral surgery on a daily basis and, despite surgical skills and expertise, complications may occur. Complications observed during or after third molar removal may include pain, swelling, bleeding, infection, sinus perforation and nerve damage. Fortunately, with a proper management and a good surgical technique, the incidence of such events is low. Subcutaneous emphysema associated with dental extraction occurs when t...

Molar incisor hypomineralization: current research evidences

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Manikandan Ekambaram

2016-06-01

Full Text Available Molar-Incisor Hypomineralization (MIH is a condition of systemic origin that involves one to four first permanent molar teeth and often associated with affected incisors. Although several associations to prenatal/perinatal childhood medical conditions have been reported, the etiology of MIH still remains unclear. The degree of enamel hypomineralization in the affected teeth can vary and the clinical problems associated with the teeth include increased susceptibility to caries, rapid wear, and post-eruptive enamel breakdown. Affected teeth are extremely challenging to treat as the enamel is porous, sensitive and treating clinicians might encounter great difficulty in achieving profound anaesthesia. The first part of thispresentation will give an update on prevalence, potential etiological factors, and management strategies of this condition. The second part of the presentation will cover a systematic review results on bonding strategies to hypomineralized enamel.

Molar mass of poly(ethylene terephthalate) (PET) during ultimate uniaxial drawing

NARCIS (Netherlands)

Göschel, U.; Cools, P.J.C.H.

2000-01-01

The changes of the average molar mass Mw, Mn, Mz, and molar mass distributions during multistep uniaxial drawing of poly(ethylene terephthalate) (PET) to achieve ultimate mechanical properties have been studied in detail by means of size exclusion chromatography (SEC) with triple detection:

Molar-Mass of Poly(Ethylene-Terephthalate) (PET) During Ultimate Uniaxial Drawing

NARCIS (Netherlands)

Göschel, A.G.P.U.; Cools, P.J.C.H.

2000-01-01

The changes of the average molar mass Mw, Mn, Mz, and molar mass distributions during multistep uniaxial drawing of poly(ethylene terephthalate) (PET) to achieve ultimate mechanical properties have been studied in detail by means of size exclusion chromatography (SEC) with triple detection:

Micro-CT analyses of apical enlargement and molar root canal complexity

DEFF Research Database (Denmark)

Markvart, Merete; Darvann, Tron Andre; Larsen, Per

2012-01-01

AIM: To compare the effectiveness of two rotary hybrid instrumentation techniques with focus on apical enlargement in molar teeth and to quantify and visualize spatial details of instrumentation efficacy in root canals of different complexity. METHODOLOGY: Maxillary and mandibular molar teeth wer...

Clinical treatment approach of a child with molar incisor hypomineralization (MIH combined with malocclusion.

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Rossitza Kabaktchieva

2012-04-01

Full Text Available Introduction. Molar incisor hypomineralization (MIH was defined as "hypomineralisation of systemic origin of permanent first molars, frequently associated with affected incisors". MIH includes the presence of demarcated opacity, post eruptive enamel breakdown, atypical restoration. Тhe approach to management suggested: risk identification, early diagnosis, remineralization for prevention of caries and post eruption breakdown, restorations. The clinicians very seldom notice that children with MIH usually have both- hypomineralisation and malocclusions, and they do not discuss combine treatment plan.Aim. To present our interdisciplinary approach to a patient with MIH, combined with malocclusion.Material and methods. We are presenting 9 year old child with contusio and fractura coronae dentis noncomplicata, distal occlusion, overjet, overbite and retrusion. Two consecutive stages were defined: First stage:- Professional oral hygiene and local remineralisation therapy- Vital pulp therapy of tooth 21 - Space gaining for restoration of the lost height of the molars by the means of posterior bite-plane removable appliance- Restoration of the molars with metal inlays- Lingual tipping of the lower incisorsSecond stage:- Class II correction- Growth control Results.First phase: - The tooth 21 was restored with aesthetic composite material;- Occlusion was raised with occlusal restorations (inleys and orthodontic appliance. Second phase:Medialisation of mandible and holding maxillary growth with functional appliance and occipital EOA until class one occlusal relations.Conclusion. Children with MIH should be examined and treated complex in collaboration with orthodontist and if necessary by other specialists too.

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

Science.gov (United States)

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

2016-01-01

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

Dispositivo de seguridad para controlar mejor el tercer molar impactado durante exodoncia: Una nueva técnica Security device for a better control of impacted third molars during exodontia: A new technique

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F. Hernández Altemir

2005-04-01

Full Text Available El desplazamiento accidental del tercer molar impactado es una complicación que ocurre de vez en cuando durante la exodoncia. La recuperación de estos dientes accidentalmente desplazados puede ser compleja debido a la mala visibilidad y el espacio limitado. Describimos una técnica fácil basada en un sistema de anclaje para controlar mejor los terceros molares impactados durante la exodoncia.Accidental displacement of impacted third molars is a complication that occasionally occurs during exodontia. The retrieval of these accidentally displaced third molars may be complex due to poor visibility and limited space. We describe an easy technique for a better control of impacted third molars during exodontia based on an anchoring system.

Four osteotomy methods with piezosurgery to remove complicated mandibular third molars: a retrospective study.

Science.gov (United States)

Ge, Jing; Yang, Chi; Zheng, Jia-Wei; He, Dong-Mei; Zheng, Ling-Yan; Hu, Ying-Kai

2014-11-01

Piezosurgery has been used widely in oral and maxillofacial surgery, but there has been no report systematically describing an osteotomy method with piezosurgery for complicated mandibular third molar removal. The aim of this study was to introduce 4 osteotomy methods using piezosurgery and evaluate their effects. A retrospective study was conducted of patients with a complicated impacted mandibular third molar requiring extraction. The predictor variable was the extraction technique. Four osteotomy methods using piezosurgery were tested according to different impaction types: method 1 involved complete bone removal; method 2 involved segmental bone removal; method 3 involved bone removal combined with tooth splitting; and method 4 involved block bone removal. Outcome variables were success rate, operative time, major complications (including nerve injury, mandible fracture, severe hematoma, or severe edema), and serious pyogenic infection. Data were analyzed using descriptive statistics. The study was composed of 55 patients with 74 complicated impacted mandibular third molars. All impacted mandibular third molars were removed successfully. The average surgical time was 15 minutes (range, 8 to 26 minutes). Thirty-eight molars (51.4%) were extracted by method 1, 18 molars (24.3%) by method 2, 12 molars (16.2%) by method 3, and 6 molars (8.1%) by method 4. Two cases (2.7%) developed postoperative infections and recovered within 1 week using drainage and antibiotic administration. The 4 osteotomy methods with piezosurgery provide effective ways of removing complicated impacted mandibular third molars. Copyright © 2014 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.