Accuracy of cone-beam computed tomography in measuring the thickness of radicular dentin

Abstract The purpose of this study was to evaluate the accuracy of Cone-Beam Computed Tomography (CBCT) in measuring radicular dentin thickness focused on intraradicular post placement planning treatment. Ten single-rooted human premolars were selected. The teeth were divided into three segments (cervical, middle and apical). The coronal face of the apical and middle sections was selected for the dentin thickness assessment; which was measured from the external root surface to the root canal wall, on the buccal, lingual, mesial, and distal surfaces of each tooth. In situ anatomical measurement was the reference standard, and the corresponding axial CBCT imaging were evaluated by the i-CAT software. The one-way ANOVA test and the Bonferroni post hoc test were applied to compare the groups (p>0.05). CBCT imaging measurements (p=0.003) overestimated the radicular dentin thickness compared to the reference standard. Descriptive analysis showed that the greatest difference between the reference standard and the tomographic measurement means were 0.20 mm. One-way ANOVA test found the statistical significant difference among group's measurements. Bonferroni correction demonstrated statistically significant difference only related lingual surface for the CBCT imaging measurements. CBCT imaging measurements overestimated the radicular dentin thickness. However, the measurement difference was clinically acceptable.

Resumo O objetivo deste estudo foi avaliar a precisão da Tomografia Computadorizada de Feixe Cônico (TCFC) na mensuração da espessura da dentina radicular no planejamento de tratamento envolvendo a cimentação de pinos intrarradiculares. Dez pré-molares humanos unirradiculares foram selecionados. Os dentes foram divididos em três segmentos (cervical, médio e apical). A face coronal dos terços apical e médio foi selecionada para a avaliação da espessura da dentina; que foi medida a partir da superfície externa da raiz até a parede do canal radicular, nas superfícies vestibular, lingual, mesial e distal de cada dente. A medida anatômica in situ foi o padrão de referência, e a imagem de TCFC axial correspondente foi avaliada pelo software i-CAT. O teste de 1-fator ANOVA e o teste post hoc de Bonferroni foram aplicados para comparar os grupos (p>0,05). As medidas de imagem da TCFC (p=0,003) superestimaram a espessura da dentina radicular em comparação a referência padrão. A análise descritiva mostrou que a maior diferença entre a referência padrão e a medida tomográfica foi de 0,20 mm. O teste ANOVA encontrou a diferença de significância estatística entre as medidas do grupo. A correção de Bonferroni demonstrou diferença estatisticamente significante apenas relacionada às medidas de imagem da TCFC. A medida de imagem da TCFC superestimou a espessura da dentina radicular. No entanto, a diferença de medição foi clinicamente aceitável.

Is it necessary to pre-treat Dentine before GIC Restorations? Evidence from an in Vitro Study / É necessário pré tratar a dentina antes das restaurações de CIV? Evidência de um estudo in vitro

ABSTRACT The aim of this study was to assess the influence of differentpretreatmentapproaches on glass ionomer cement (GIC)bond strength (BS) to dentine. Sixty bovine incisors wereallocated into six groups according to substrate - sound orcariesaffecteddentine; and substrate pretreatmentapproach -no conditioning (control), polyacrylic acid for 10 s andphosphoric acid for 7 s. Teeth in the cariesaffecteddentinegroup were previously submitted to cariogenic pHcyclingchallenge. After dentine pretreatment,according to experi mentalgroups, polyethylene tubes were placed on flat dentinesurfaces and filled with GIC. Teeth were stored in distilledwater for 24 h at 37 °C and then submitted to microshear test(0.5 mm/min). Failure pattern analysis was performed understereomicroscope (400x). Data were analysed using twowayANOVA and Tukey's test (α=5%). Statistically significantdifferences were found for the pretreatmentapproach,regardless of substrate (p<0.001). The polyacrylic acid groupand control group had similar BS values, and were both betterthan the phosphoric acid group. In general, GIC had betterbonding performance in sound dentine than in cariesaffecteddentine. In conclusion, dentine pretreatmentwith polyacrylicacid did not improve the performance of GIC restoration onclinically relevant substrates.

RESUMO O objetivo deste estudo foi avaliar a influência de diferentesprétratamentosna resistência de união (RU) de cimentos deionômero de vidro (CIV) a dentina. Sessenta incisivos bovinosforam alocados em 6 grupos de acordo com o substrato -hígido ou cariado; e com a abordagem de prétratamento-sem condicionamento (controle), ácido poliacrílico por 10 s, eácido fosfórico por 7 s. Os dentes pertencentes aos grupos dedentina cariada foram previamente submetidos ao desafiocariogênico por meio da ciclagem de pH. Após o prétratamentoda dentina, de acordo com os grupos experimentais,tubos de polietileno foram colocados sobre superfícies planas dedentina e preenchidos com CIV. Os dentes foram armazenadosem água destilada por 24 h a 37°C e então submetidos ao testede microcisalhamento (0,5 mm/min). A análise do padrão defratura foi realizada em estereomicroscópio (400x). Os dadosobtidos foram analisados usando ANOVA de dois fatores e testede Tukey (α=5%). Diferença estatisticamente significante foiencontrada para as diferentes abordagens de prétratamento,independente do substrato (pp<0,001). Aplicação de ácidopoliacrílico resultou em valores de RU similares aos do grupocontrole. Entretanto, ambos os grupos mostraram um melhordesempenho quando comparado a aplicação de ácidofosfórico. De forma geral, CIV apresentou melho5 desempenhoadesivo em dentina sadia quando comparada a dentinacariada. Em conclusão, o prétratamentoem dentina comácido poliacrílico não melhora o desempenho das restauraçõesde CIV em substratos clinicamente relevantes.

Ultrastructural Alterations and Physical Changes on Bovine Dentin After Internal Bleaching with 35 % Hydrogen Peroxide / Alteraciones Ultraestructurales y Cambios Físicos en la Dentina Bovina Después del Blanqueamiento Interior con un 35 % de Peróxido de Hidrógeno

ABSTRACT: The aim of the study was to investigate the effect of internal bleaching on physical proprieties and ultrastructure of the bovine dentin.40 bovine incisors were used, divided in four experimental groups: control group, composed by teeth that did not receive the bleaching agent (G1); teeth submitted to a single internal bleaching session (G2); teeth submitted to two internal bleaching sessions (G3); teeth submitted to three internal bleaching sessions (G4). In each of the sessions, 35 % hydrogen peroxide was applied for 45 minutes on the dentin surface. Tests were performed (microhardness and roughness) and were analyzed using one-way analysis of variance (ANOVA) and Tukey's post-hoc test (p≤0.05). Electromicrographs were captured for quality analysis. In the analysis of the superficial microhardness of the dentin, the internal bleaching reduced the Knoop microhardness since the first session, being observed statistically significant differences between the experimental groups and the control. The surface roughness gradually increased in the G2, G3 and G4 groups, but only G4 presented a statistically significant difference from the others. The qualitatively evaluated electromicrographs showed damage to the dentin ultrastructure, with areas of erosion and greater involvement of the intertubular when compared to peritubular dentin. Internal bleaching with 35 % hydrogen peroxide caused injuries in bovine dentin from the first treatment session. Both modifications in physical properties and dentin ultrastructure have been identified. These changes were intensified the higher the number of dentin internal bleaching sessions was exposed.

RESUMEN: El objetivo de este estudio fue investigar el efecto del blanqueamiento interno sobre las propiedades físicas y la ultraestructura de la dentina bovina. Se utilizaron 40 incisivos bovinos, divididos en cuatro grupos experimentales: grupo de control, compuesto por dientes que no recibieron el agente blanqueador (G1); dientes sometidos a una única sesión interna de blanqueamiento (G2); dientes sometidos a dos sesiones internas de blanqueamiento (G3); dientes sometidos a tres sesiones internas de blanqueamiento (G4). En cada una de las sesiones, se aplicó peróxido de hidrógeno al 35 % durante 45 minutos en la superficie de la dentina. Se realizaron pruebas (microdureza y rugosidad). Los datos se analizaron mediante análisis de varianza de una vía (ANOVA) y prueba post-hoc de Tukey (p≤0,05). Las electromicrografías fueron capturadas para el análisis cualitativo. En el análisis de la microdureza superficial de la dentina, el blanqueamiento interno redujo la microdureza de Knoop desde la primera sesión, observándose diferencias estadísticamente significativas entre los grupos experimentales y el control [NF2]. La rugosidad superficial aumentó gradualmente en los grupos G2, G3 y G4, pero solo G4 presentó una diferencia estadísticamente significativa con respecto a los otros [NF3]. Las electromicrografías evaluadas cualitativamente mostraron daño a la ultraestructura de la dentina, con áreas de erosión y una mayor participación de la dentina intertubular en comparación con la dentina peritubular. El blanqueamiento interno con peróxido de hidrógeno al 35 % causó lesiones en la dentina bovina en la primera sesión del tratamiento. Ambas modificaciones, en propiedades físicas y en la ultraestructura dentinaria, han sido identificadas. Estos cambios se intensificaron a medida que se expuso a mayor número de sesiones de blanqueamiento interno en la dentina.

Utilização da técnica da dentina úmida por etanol na adesão dentinária: influência in vitro da smear layer, avaliação clínica com diferentes protocolos adesivos e revisão sistemática / Use of etanol-wet-bonding technique in dentin adhesion: smear layer in vitro influence, clinical trial with different adhesives protocols and systematic review

Este estudo foi composto por um estudo in vitro, um estudo clínico randomizado, controlado e duplo cego e uma revisão sistemática, com objetivo de compreender e avaliar a aplicabilidade da técnica da dentina úmida por etanol (EWBT) em procedimentos restauradores. Estudo laboratorial: 48 incisivos bovinos foram divididos em 2 grupos, com a utilização ou não de etanol anterior ao sistema adesivo universal (Single Bond Universal) no modo autocondicionante. Em seguida blocos de resina composta (Filtek Z350 xt) foram confeccionados. A interface adesiva foi analisada, antes e após envelhecimento por 6 meses em água, com relação à nanodureza e módulo de elasticidade e em microscopia eletrônica de varredura (MEV) após a realização de nanoinfiltração com nitrato de prata. Os dados de nanodureza e módulo de elasticidade foram analisados estatisticamente com ANOVA e teste de Tukey (α=5%). Houve diferença estatística para as áreas avaliadas (p<0.001) e também para a aplicação do etanol (p<0.001). A dentina apresentou valores maiores de nanodureza quando comparado com a camada híbrida. EWBT foi capaz de manter as propriedades da interface adesiva mesmo após envelhecimento. Estudo clínico randomizado: Os voluntários receberam restaurações em cavidades do tipo classe V, provenientes de lesões cervicais não cariosas, com extensão e profundidade de no mínimo 1 mm. As restaurações foram realizadas aleatoriamente, de acordo com a divisão dos grupos, sendo o grupo controle sem pré-tratamento dentinário (SE) e três grupos com a intervenção, sendo associado com adesivo de 3 passos (E); hidrófobo (EB) ou com adesivo de 2 passos (EU). As restaurações foram avaliadas, por examinadores devidamente calibrados no início do estudo, após 7 dias, 6 e 18 meses, utilizando o critério USPHS modificado. Os dados foram analisados com testes chi-quadrado e KaplanMeier. O grupo com adesivo hidrófobo apresentou maior taxa de falha para retenção quando comparada aos demais grupos, tanto em 6 quanto em 18 meses. Revisão sistemática: Foram pesquisadas as principais bases de dados eletrônicas com a estratégia de busca definida de acordo com a pergunta de pesquisa e estratégia PICO, sendo P: dentes com lesões cervicais não cariosas; I: protocolo adesivo utilizando EWBT; C: protocolo adesivo convencional. Após análise do título e resumo dos artigos pré-selecionados, seguindo a questão PICO, 19 artigos laboratoriais e 3 estudos clínicos relacionados ao tema tiveram os dados extraídos. O risco de viés dos artigos selecionados foi estimado, sendo que para a maioria dos estudos laboratoriais e clínicos foi considerado baixo. Para os estudos laboratoriais houve diferença, sendo que o grupo controle apresentou melhores resultados quando comparado à EWBT. Com relação aos estudos clínicos não houve diferença entre os grupos controle e EWBT(AU)

This study was composed by an in vitro study, a randomized, controlled and double blind clinical trial, and a systematic review, aiming to understand and evaluate the applicability of ethanol-wet-bonding technique (EWBT) in restorative procedures. Laboratory study: 48 bovine incisors were divided into 2 groups, according to EWBT use prior to the universal adhesive system (Single Bond Universal) in the self-etch mode. Blocks of composite resin (Filtek Z350 xt) were made. The adhesive interface was analyzed, on baseline and 6 months of water aging, by scanning electron microscopy (SEM) after nanoleakage with silver nitrate, besides the nanohardness and elastic modulus. The data of nanohardness and elastic modulus were statistically analyzed with ANOVA and Tukey test (α=5%). There was a statistically significant difference for the areas evaluated, in which dentin presented higher values, for nanohardness, than the hybrid layer (p<0.001) and for the use of ethanol (p<0.001). The use of ethanol was able to maintain the properties of the adhesive layer even after aging. Randomized clinical trial: The volunteers received restorations in class V cavities from non-carious cervical lesions (NCCL), with cavity extension and depth of at least 1 mm. The restorations were randomly performed according to group division: no ethanol dentin pretreatment (SE), with ethanol dentin pretreatment in association with 3-step (E) or 2-step (EU) or adhesive, or hydrophobic adhesive (EB). The restorations were evaluated by calibrated examiners at baseline, after 7 days, 6 and 18 months using the modified USPHS criteria. All data were statistically analyzed at Chi square and survival test (α=5%). The hydrophobic adhesive group presented higher failure rate for retention when compared to the other groups, both at 6 and 18 months followup. Systematic review: Main electronic databases were used for search and the strategy was defined according to the research question and PICO strategy, where P: teeth with NCCL; I: adhesive protocol using EWBT; C: conventional adhesive protocol; O: long-term clinical outcome after EWBT. After analyzing the title and abstract of the pre-selected articles, following the PICO question, 19 laboratory studies and 3 clinical trials related to EWBT. The data from selected studies were extracted and then, the risk of bias was estimated. For laboratory studies it was considered high and for clinical trials was considered low risk of bias. After statistical analysis, for laboratory studies the control group presented better results when compared to EWBT. Regarding the clinical studies, there was no difference between control and EWBT groups(AU)

Effect of aging on dentinal crack formation after treatment and retreatment procedures: a micro-ct study

Abstract In order to evaluate the volume of dentinal cracks taking into account the age of the dentin and the type of file system used for endodontic procedures, forty freshly extracted single-rooted lower incisive teeth presenting similar root volume, were divided into two groups according to the age of the patient: Group Young (18 - 30 years old) and Group Old (60 years old or more). Each specimen was scanned by microcomputed tomography (micro-CT) in three stages: (i) before any treatment, (ii) after endodontic treatment with Reciproc files (REC), and (iii) after subsequent endodontic retreatment. Each group was subdivided into two subgroups, according to the retreatment technique used: retreatment with REC or with ProTaper Universal Retreatment (PUR) files. For each subgroup, the images were analyzed for differences in the volume of dentinal cracks in the middle and apical thirds of the teeth , according to the dentin age. In both stages (before and after instrumentation), the micro-CT images of the old root dentin presented with higher volume of cracks than those of the young root dentin, statistical significance notwithstanding (p>0.01). The use of REC files appeared to have no statistically significant differences in the generation of cracks in any type of root dentin when compared with PUR files (p>0.01). When retreated with PUR, the old root dentin presented with a significantly higher volume of cracks (p<0.01) when compared with the old root dentin initially.

Resumo Para avaliar o volume de fissuras dentinárias levando em consideração a idade da dentina e o tipo de sistema de limas utilizadas para procedimentos endodônticos, 40 dentes unirradiculares, incisivos inferiores, apresentando similar volume radicular, recentemente extraídos foram divididos em dois grupos de acordo com a idade do paciente: Grupo Jovem (18 a 30 anos) e Grupo Idoso (60 anos ou mais). Cada espécime foi scaneada por microtomografia computadorizada (micro-CT) em três estágios: (i) antes de qualquer tratamento, (ii) após tratamento endodôntico com limas Reciproc (REC) e (iii) após subsequente retratamento endodôntico. Cada grupo foi subdividido em dois subgrupos, de acordo com a técnica de retratamento utilizada: retratamento com REC ou com lima ProTaper Universal Retreatment (PUR). As imagens foram analisadas quanto às diferenças no volume das fissuras dentinárias nos terços médio e apical dos dentes de acordo com a idade da dentina. Em ambos os estágios (antes e depois da instrumentação), as imagens de micro-CT da dentina radicular idosa apresentaram maior volume de trincas do que as jovens, sem significância estatística (p>0.01). O uso das limas REC mostram não ter diferença estatística significante na geração de fissuras, em qualquer tipo de dentina, quando comparadas às limas PUR (p>0.01). Quando retratada com PUR, a dentina radicular idosa apresentou um volume de trincas significativamente maior (p<0.01) quando comparado com a dentina radicular idosa inicialmente.

Validation of cone beam computed tomography as a clinical imaging method for dentin thickness measurement in the danger zone of mandibular molars / Validação da tomografia computadorizada de feixe cônico como um étodo de imagem clínico para mensuração da espessura dentinária na zona de risco de molares inferiores

Objective: to verify the accuracy of cone beam computedtomography (CBCT) for measuring dentin thicknessin the danger zone of mandibular molars in order to validatethis method to be used as a clinical auxiliary. Materialsand method: dentin thickness of the distal wall ofmesial canals was measured at 2 mm of furcation areain ten mandibular molars before and after preparation ofcervical and middle thirds. CBCT (0.25 mm voxel size)and stereomicroscopy images were acquired twice foreach sample. CBCT axial images and stereomicroscopeimages were evaluated by a calibrated examiner. Statisticalanalysis was performed using Mann-Whitney testin order to investigate whether CBCT images providedtrusted values. Results: mean values of initial (1.23 versus1.24 mm) and final measurements (0.88 versus 0.87mm) obtained with, respectively, CBCT and stereomicroscopemethods did not show statistical differences(P > 0.5). Conclusion: CBCT images provide high accuracyfor measuring dentin thickness in the danger zoneof mandibular molars. (AU)

Objetivo: avaliar a acurácia da tomografia computadorizada de feixe cônico (TCFC) para mensurar a espessura dentinária na zona de risco de molares inferiores e validar este método, a fim de usá-lo como um auxiliar clínico. Materiais e método: a espessura dentinária da parede distal dos canais mesiais foi medida a 2 mm da área de furca em dez molares inferiores, antes e após a preparação dos terços médio e cervical. Foram adquiridas imagens por TCFC (tamanho do voxel de 0,25 mm) e estereomicroscopia. Um examinador treinado e calibrado avaliou as tomografias no plano axial e as imagens de estereomicroscopia. A análise estatística foi realizada com o teste Mann-Whitney, para verificar se as imagens tomográficas forneceram valores comparáveis à estereomicroscopia. Resultados: a média dos valores obtidos, respectivamente, após as mensurações iniciais (1,23 versus 1,24 mm) e finais (0,88 versus 0,87 mm) das imagens de TCFC e estereomicroscopia não mostraram diferença estatisticamente significativa entre os métodos (P > 0,5). Conclusão: a TCFC produz imagens acuradas para a mensuração da espessura dentinária na zona de risco de molares inferiores. (AU)

Accuracy of visual and image-based ICDAS criteria compared with a micro-CT gold standard for caries detection on occlusal surfaces

Abstract The aim of this study was to check the in vitro accuracy of ICDAS criteria on digital images compared to visual examination for the diagnosis of occlusal caries against a micro-CT gold standard. ICDAS was scored in 40 extracted permanent molars by means of visual inspection and stereomicroscopic images. Visual examinations were performed in duplicate and at a one-week interval by three different calibrated examiners. The analysis of digital images by ICDAS criteria was also performed in duplicate, 1 month after visual examinations. The detection methods were compared by means of sensitivity, specificity, area under the curve, predictive positive and negative values, and accuracy for two different thresholds (1- sound vs. carious teeth; 2- tooth requiring operative vs. non-operative treatment). Sensitivity and accuracy values for threshold 1 in the visual ICDAS and image-based ICDAS methods were high for sensitivity (0.93 and 0.97) and for accuracy (0.83 and 0.85), but low for specificity (0.55 for both methods). Specificity values for threshold 2 were 0.77 and 0.82, while sensitivity was 0.33 and 0.28 for each method. Spearman's rank correlation coefficient was 0.53 and 0.43 (p<0.05) for visual and image-based ICDAS compared to the gold standard scores. Both visual and image-based ICDAS scores were similar to each other in terms of diagnostic accuracy when compared to the micro-CT gold standard. Low specificity for the presence of caries and sensitivity for the detection of caries requiring operative treatment were found.

A randomized clinical trial on the sealing of occlusal carious lesions: 3-4-year results

Abstract This randomized clinical trial aimed to assess the efficacy of sealing occlusal carious lesions in permanent teeth. The sample consisted of 54 occlusal carious lesions in permanent molars and premolars of 49 patients aged 8–43 years (median: 19 years). The inclusion criteria comprised the presence of a cavity with no access allowing biofilm control. The maximum depth of the lesion was the middle third of the dentin thickness, as assessed by bitewing radiography. The teeth were randomly assigned to sealant treatment (n = 28) or restorative treatment (n = 26). Clinical and radiographic examinations were performed after 1 year and after 3–4 years. The outcomes depended on the clinical performance of the sealant/restoration and the control of caries progression observed radiographically. Survival analysis was performed to assess success rates. Over the 3-4 years of monitoring, 2 sealants were totally lost, 1 needed repair, and 1 showed caries progression, totaling 4 failures in the sealant group. In the restoration group, 1 failure was observed (in need of repair). The success rates were 76% and 94% in the sealant and the restoration groups, respectively (p > 0.05). The sealing of occlusal carious lesions in permanent teeth succeeded in controlling caries over a 3–4-year period. However, sealed carious lesions require patient compliance in attending regular follow-ups to control the occurrence of clinical failures of the sealants.

Reliability of Logicon caries detector in the detection and depth assessment of dental caries: An in-vitro study.

Background: Digital radiography has so far not resulted in improved rates of proximal caries detection. Historically, automated caries detection tools have been largely academic. Opinions regarding the performance of the only such commercially available tool, viz., Logicon caries Detector (LCD) have been equivocal. This study was conducted to evaluate the reliability of LCD in the detection and depth assessment of proximal caries. Materials and Methods: Digital images were obtained of 100 proximal tooth surfaces using the Kodak RVG 5000 sensor and analyzed by three observers. The images were then analyzed by the principal investigator using the LCD software. The teeth were then sectioned and magnified photographic images were obtained which were taken as the gold standard. All the grades were entered in proformas and the data were statistically analyzed using the chi-square test. Five parameters of reliability were calculated. Results: The sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy of LCD for the grade No caries were 33, 96, 73, 82, and 81%, respectively; for the grade Enamel caries were 5, 97, 33, 80, and 79%, respectively; and for the grade Dentin caries were 100, 96, 50, 100, and 96%, respectively. Conclusions: In conclusion, LCD appears to be more reliable in ruling out (both enamel and dentin) caries than in detecting caries.

A color contrast aided density imaging technique to differentiate between dental hard tissues and its relevance.

Aim: Radiographic interpretation of a disease requires knowledge about normal structures. The calcifying jaw diseases can range from radiolucent areas to varying degrees of calcification. Therefore, it is vital to differentiate radiographically between various hard tissues. Materials and Methods: We have illustrated the use of computed tomography scan to quantify the calcified structures as dentin and enamel in a case of ameloblastic fibro-odontoma. Results: The enamel, dentin and cementum showed different values. Conclusion: The "Dentascan" can be used to distinguish the hard tissues in a variety of calcifying diseases of jaws.

The relative diagnostic yields of clinical, FOTI and radiographic examinations for the detection of approximal caries in youngsters.

Background: The detection of carious lesions in the initial stages of development is very important in order to prevent the occurrence of cavitation. Aims and Objectives: The aim of the present study was to compare three methods-visual examination, FOTI, and bitewing radiographic examination-for the detection of noncavitated and cavitated approximal carious lesions. Materials and Methods: Seventy students (mean age 14 years) with low caries prevalence were examined by three examiners. The tooth surfaces judged as having caries by at least one examiner or one diagnostic method were scheduled for tooth separation. Results: The results showed that the incorporation of FOTI and radiographic examination represented an additional diagnostic yield of 50% and about 110%, respectively, compared to clinical examination alone. Conclusion: We conclude that FOTI or radiographic examination, or both, used as adjuncts to clinical examination, could improve the detection of noncavitated and cavitated approximal carious lesions. Although FOTI should not replace bitewing radiographic examination, it does seem to have additional value for the detection of carious lesions on approximal surfaces of the posterior teeth in school children with low caries prevalence.

[Determination of sexual dimorphism from maxillary premolars thickness in bitewing radiography]

Sexual dimorphism plays an important role in forensic medicine. Sexual differences in the human skeleton have been well studied in many populations but odontometric analysis of the human sexual variation has been less investigated. This study was designed to determine the sexual dimorphism by enamel and dentin thickness in radiography of maxillary premolars in an Iranian sample.For this descriptive and analytic study, 100 individuals, [so males and so females] aged 20 to 35 years old, from an Iranian population were selected. The bitewing radiographs of the right permanent maxillary premolars were taken under standard conditions using a film holder. The radiographs were digitally scanned, and after calculation of image magnification, maximum mesiodistal diameter of dentin, and mesial and distal enamel margins were measured. Data were analysed by SPSS statistical software using T- test and Step function. Mesiodistal dentin dimension was significantly greater in males, but there was no sexual dimorphism in the maximum mesiodistal diameter of crown, and distal margin of enamel. Enamel was significantly thicker on the mesial margin in females. First premolar displayed greater sexual dimorphism than second premolar. According to the study results, for determining sexual dimorphism in forensic medicin, the mesiodistal dentin dimension as well as the width of the enamel mesial margin of upper premolar teeth are acceptable parameters in Iranian population