Multipopulation evaluation of the internal morphology of mandibular first premolars from different South American countries. A micro-computed tomography study.

OBJECTIVE: To evaluate and compare several anatomical parameters of mandibular first premolars from individuals from different Latin American countries using micro-computed tomography. DESIGN: Five hundred extracted mandibular first premolars from Brazilian, Argentinian, Chilean, Colombian, and Ecuadorian individuals were scanned using micro-computed tomography (n = 100 teeth/country). Root canal configurations were classified according to established parameters. Analyses also included: canal volume and surface area, structure model index, distances from the apical foramen to the root apex or the cementoenamel junction, major/minor apical canal diameters, canal orifice shape, and prevalence of ramifications. RESULTS: A single root was the most common anatomy in all countries (range, 97%-100%). Vertucci's type-I canal was the most frequent configuration (range, 36%-66%), followed by C-shaped and type-V canals. The oval-shaped canal orifice was the most predominant in all countries (range, 34%-58%), followed by the circular shape (range, 16%-47%). C-shaped canals occurred in all subpopulations (range, 14%-26%), always associated with radicular grooves. Ranges for canal ramifications were as follows: accessory canals, 36%-73%; lateral canals, 4%-12%; and apical delta, 4%-14% of the teeth. Many anatomic parameters differed significantly between countries (P < .05). CONCLUSIONS: Vertucci's types-I and -V, and C-shaped canals were the most prevalent configurations in the subpopulations investigated. Accessory canals and several complex anatomies were found, with some significantly different frequencies between countries.

The groove configuration of mandibular molars of malaysians of mongoloid ancestry / Configuración del surco de los molares mandibulares de los malayos de ascendencia mongoloide

Aim: Variation in dental structures is widely accepted as a combination of multiple factors such as gender, environmental effects and genetics. However, the characterization of similarities and differences in dental morphology has been lacking in relation to the factors mentioned. This study aims to assess and compare the variations in traits in mandibular molars and the influence of gender and ethnicity in affecting these traits amongst the Malaysian population of Mongoloid ancestry. Materials and Methods: Our study population was 180 dental casts of patients, from 15 to 40 years old, comprising 56 Malays and 124 Chinese; 60 were males and 120 were females. Traits like groove pattern, number of cusps, protostylids and deflecting wrinkles were observed, scored, and recorded. Results: This study revealed that the most common mandibular first molar (M1) was characterized by 5 cusps and displayed 'Y' groove pattern, while the most common mandibular second molar (M2) had 4 cusps and exhibited a groove pattern that resembled a '+'. Notably, all the traits studied were bilaterally symmetrical, except for the groove pattern of M1, while sexual dimorphism was observed in groove patterns of M2. Conclusions: This study found that M1 had a preponderance of 5 cusps with 'Y' groove pattern, while M2 were typically 4-cusped with '+' groove pattern.

Objetivo: La variación en las estructuras dentales es ampliamente aceptada como el resultado de una combinación de múltiples factores como el género, los efectos ambientales y la genética. Sin embargo, ha faltado la caracterización de similitudes y diferencias en la morfología dental en relación a los factores mencionados. Este estudio tiene como objetivo evaluar y comparar las variaciones en los rasgos de los molares mandibulares y la influencia del género y la etnia al afectar estos rasgos entre la población malaya de ascendencia mongoloide. Materiales y Métodos: Nuestra población de estudio fue de 180 modelos dentales de pacientes, de 15 a 40 años,conformados por 56 malayos y 124 chinos; 60 eran hombres y 120 eran mujeres. Se observaron, puntuaron y registraron rasgos como el patrón de surcos, el número de cúspides, los protostílidos y las arrugas desviadas. Resultados: Este estudio reveló que el primer molar mandibular más común (M1) se caracterizaba por 5 cúspides y mostraba un patrón de ranura en 'Y', mientras que el segundo molar mandibular más común (M2) tenía 4 cúspides y exhibía un patrón de ranura que se parecía a un ' +'. En particular, todos los rasgos estudiados eran bilateralmente simétricos, excepto el patrón de surco de M1, mientras que se observó dimorfismo sexual en los patrones de surco de M2. Conclusión: Este estudio encontró que M1 tenía una preponderancia de 5 cúspides con un patrón de ranura en 'Y', mientras que M2 tenía típicamente 4 cúspides con un patrón de ranura '+'.

Can maxillary molar dimensions predict the presence of the second mesiobuccal canal?

OBJECTIVE: To evaluate the potential of maxillary molar dimensions as predictors of the presence of the second mesiobuccal (MB2) canal. METHODS: Micro-computed tomography scans were obtained from 47 maxillary molars, out of which 26 had the MB2 canal. The distance between root canals, extension of the canals, and thickness of surrounding dentin were obtained from axial images at the furcation level, 3 mm from the apex, and 5 mm from the apex. The association between the measurements and the presence of the MB2 canal was assessed using multiple logistic regression and odds ratio. RESULTS: At the furcation level, the bucco-palatal extension of the MB1 canal significantly decreased the chance of the presence of the MB2 canal. Regarding the thickness of surrounding dentin measurements, the mesial and distal aspects of the MB1 canal at 3 mm from the apex were statistically significant to decrease and increase the chance of presence of the MB2 canal, respectively. Regarding the extension of the canals, only buccal-palatal extension seems to decrease the chance of the presence of the MB2 canal. CONCLUSION: The presence of the MB2 canal in the mesiobuccal root of maxillary molars is associated with the bucco-palatal extension and surrounding dentin thickness of the first mesiobuccal canal, and seems to be unrelated to the dimensions of the distobuccal and palatal roots.

Resin Composites in Posterior Teeth: Clinical Performance and Direct Restorative Techniques.

Resin composites are the most versatile restorative materials used in dentistry and the first choice for restoring posterior teeth. This article reviews aspects that influence the clinical performance of composite restorations and addresses clinically relevant issues regarding different direct techniques for restoring posterior teeth that could be performed in varied clinical situations. The article discusses the results of long-term clinical trials with resin composites and the materials available in the market for posterior restorations. The importance of photoactivation is presented, including aspects concerning the improvement of the efficiency of light-curing procedures. With regard to the restorative techniques, the article addresses key elements and occlusion levels for restoring Class I and Class II cavities, in addition to restorative strategies using different shades/opacities of resin composites in incremental techniques, restorations using bulk-fill composites, and shade-matching composites.

Under the lens: a report on global dental morphology modules / Bajo la lupa: un reporte sobre los módulos de morfología dental a nivel global

SUMMARY: Dental morphology (DM) is the first introduction of dental graduates towards the identification of tooth; hence it is an important component of the dental curriculum. Traditionally, it is taught by manual carving of wax blocks, but the limitations of this method have been highlighted. There is a need to adopt innovative teaching methodologies to invigorate the concepts of dental anatomy (DA) and reduce the stress in teaching and learning with a proposal in standardization of training methodologies worldwide. Methods: A three-phased project was designed with an aim to collect global data related to teaching dental morphology within the dental curriculum. One dental professional actively involved in university teaching of DM subject was invited from 11 countries. The present study involved compilation of data from phase 1 questionnaire responses, followed by its discussion and analysis, and generation of preliminary report. Results: It is universally acknowledged that acquiring dental morphology knowledge by dentists is a prerequisite before they commence clinical practice. Our data points that no uniformity in DA course modules exists throughout the world and globally the subject requires curriculum redesigning. Conclusions: Consensus should be achieved amongst academicians in DM teaching and learning context. Innovative and standardized DM modules with component of computer-based and remote learning techniques should also be introduced.

La morfología dental (MD) es el primer contacto de los estudiantes de odontología con la identificación del diente; por lo tanto, es un componente importante del plan de estudios de la carrera. Tradicionalmente, se enseña mediante el tallado manual de bloques de cera, pero se han destacado las limitaciones de este método. Existe la necesidad de adoptar metodologías de enseñanza innovadoras para dinamizar los conceptos de anatomía dental (AD) y reducir el estrés en la enseñanza y el aprendizaje con una propuesta de estandarización de metodologías de formación, a nivel mundial. Métodos: Se diseñó un proyecto de tres fases con el objetivo de recopilar datos globales relacionados con la enseñanza de la morfología dental dentro del plan de estudios dental. Se invitó a un profesional de la odontología de cada uno de 11 países que participa activamente en la enseñanza universitaria de la MD. Esto incluyó la recopilación de datos de las respuestas a un cuestionario en la fase 1, seguida de su discusión y análisis, y la generación de un informe preliminar. Resultados: Se reconoce universalmente que la adquisición de conocimientos de morfología dental por parte de los odontólogos es un requisito previo antes de comenzar la práctica clínica. Nuestros datos indican que no existe uniformidad en los módulos del curso de AD en todo el mundo, por lo que el tema requiere un rediseño del plan de estudios. Conclusiones: Debe lograrse consenso entre los académicos en el contexto de enseñanza y aprendizaje de MD. También se deben introducir módulos innovadores y estandarizados de MD con componentes de aprendizaje remoto y de base digital.

Comparative study of Vertucci and Ahmed classifications to evaluate the main root canal configuration of mandibular incisors in a Brazilian population.

This study aimed to compare the main root canal configurations of mandibular incisors (MI) in a Brazilian population using Vertucci and Ahmed et al. classifications. One hundred and sixty-five human permanent MI were scanned using a micro-CT. Two examiners classified the samples according to Vertucci and Ahmed et al. classification. Kappa coefficient was employed. The majority of MI had a single root canal (52.1%). Type III Vertucci and 1 MI1-2-1 Ahmed et al. was the most common 2-canal MI (20%). In the apical third, the presence of one, two and three canals was found in 81.8%, 15.2% and 3% respectively. In the cervical and middle thirds, one, two and three canals were found in 86%, 12.2% and 1.8% respectively. Ahmed et al. classification was able to classify the entire sample studied, whereas 11 teeth (6.66%) did not fit Vertucci's classification.

Effect of Dental Course Cycle on Anatomical Knowledge and Dental Carving Ability of Dental Students.

This study assessed the effect of the course cycle on theoretical knowledge of dental morphology and the dental carving ability of dental students. Thirty-two dental students from the third semester (initial cycle) and 30 students from the eighth and tenth semesters of the dental course (end cycle) had their theoretical knowledge on dental morphology assessed using a questionnaire with ten closed questions. Their dental carving ability was also assessed using wax carvings in macro models of plaster (for the third [S3] and eight [S8] semesters) and natural-sized artificial teeth (for the tenth [S10] semester). The teeth chosen for the dental carving activity were #16 and #47. The scores were statistically analyzed using the t-test, Kruskal-Wallis test, and Mann-Whitney test (α = 0.05). Students from the initial cycle presented better theoretical knowledge than the other groups did (P < 0.007). No significant differences in carving score were found between the initial and end cycles (P > 0.05), although S10 students obtained a higher score for teeth #16 and #47 (P < 0.05). Natural-sized artificial teeth received a higher evaluation score in dental carvings than the macro models (P < 0.001). Within the limits of this study, it was possible to conclude that students from the initial cycle (S3) presented higher theoretical knowledge, whereas no difference in carving ability was observed between the initial and end cycles. The tenth semester (S10) students performed dental carvings with better quality. Furthermore, carvings in natural-sized artificial teeth presented better quality compared with the macro models.

A importância da análise do volume dentário e discrepância de Bolton para a finalização ortodôntica / The importance of analyzing dental volume and Bolton discrepancy for excellent orthodontic finishing ­ case report

Resumo Reconhecer a presença de discrepâncias no tamanho dos dentes entre os arcos mandibular e maxilar é fundamental para obtenção de um diagnóstico e tratamento ortodônticos corretos. A análise de Bolton é uma metodologia capaz de constatar discrepância no tamanho dos dentes tanto na maxila, quanto na mandíbula, o que pode afetar negativamente uma relação dentária correta, que é o esperado após o tratamento ortodôntico corretivo. No presente trabalho, é descrito um relato de caso clínico com foco na resolução da discrepância de Bolton presente nos incisivos superiores. Contudo apenas a intervenção ortodôntica pode não apresentar resultados satisfatórios no que diz respeito à estética, uma vez que características individuais dentárias (tamanho, forma, proporção, altura, largura) não se alteram com essa vertente terapêutica. Assim se faz necessário o tratamento interdisciplinar para a obtenção de melhores resultados funcionais e estéticos. A presença da discrepância de Bolton é frequente no dia a dia do ortodontista e o diagnóstico minucioso associado a um plano de tratamento adequado permite a obtenção de ótimos resultados como o observado no caso descrito.(AU)

Abstract Recognizing the presence of discrepancies in the teeth size between the mandibular and maxillary arches is essential to obtain a correct orthodontic diagnosis and treatment. Bolton analysis is a methodology able to verify discrepancies in the teeth size both in the maxilla and the mandible, that can negatively affect a correct dental relationship, which is expected after the corrective orthodontic treatment. In the present study, a clinical case report aiming to resolve Bolton discrepancy present in the upper incisors is presented. However, only orthodontic intervention may not provide satisfactory results regarding to aesthetics, as individual dental characteristics (size, shape, proportion, height, width) do not change with this therapeutic aspect. Therefore, interdisciplinary treatment is necessary to obtain better functional and aesthetic results. The presence of Bolton discrepancy is frequent in the orthodontist's day-to-day life and the detailed diagnosis associated with an adequate treatment plan allows to obtain excellent results as observed in the case described. (AU)

Educational Interventions to Improve Dental Anatomy Carving Ability of Dental Students: A Systematic Review.

This systematic review aimed to identify the level of impact of educational strategies for teaching tooth carving on the carving ability of undergraduate dental students. The PubMed-NCBI, Cochrane-CENTRAL, LILACS, Ibecs, BBO, Web of Science, and Scopus databases were searched in May 2019, for randomized controlled trials (RCTs) and two-arm non-randomized studies of interventions (NRSI) addressing educational interventions toward the dental carving of undergraduate students. Studies from the year 2000 until the search date, written in English, Portuguese, and Spanish were included. Study screening and data extraction were performed in duplicate and blinded. The data were presented narratively, considering the dental carving ability of students the primary outcome. The risk of bias was assessed using the RoB tool 2.0 and ROBINS-I, and the level of evidence was determined with GRADE. Of 3,574 studies, 6 were included, with 3 RCTs and 3 NRSIs. Very low level of evidence was provided from the NRSIs that flipped classroom (1 study; n = 140) and a student-driven revised module (1 study; n = 264) improved the carving ability of students. Additionally, there was moderate evidence of online complementary material (1 RCT; n = 30) and reinforcement class improving the carving ability of students (1 RCT; n = 29). The replacement of traditional classes by an instructional DVD (1 RCT; n = 73) and assessment of carving projects through digital systems (1 NRSI; n = 79) did not enhance the carving ability of students. Study design, risk of bias, and imprecision downgraded the level of evidence. There was a very low to moderate evidence on the effectiveness of student-driven educational approaches and complementary classes of dental anatomy in improving the dental carving ability of students.

Fink's integrated course design and taxonomy: The impact of their use in a "Basics of Dental Anatomy" course.

OBJECTIVE: This study aimed to assess whether the adjustment of Fink's Model of Integrated Course Design (ICD) with his Taxonomy of Significant Learning (hereinafter referred to as "ICD/SL") affected the academic performance of students at Universidad El Bosque in the "Basics of Dental Anatomy" course. DESIGN: For this purpose, 3 academic groups were selected: 2018/1 (55 students), 2018/2 (79 students), and 2019/1 (57 students). The control group, 2018/1, was taught without ICD/SL; the 2 treatment groups, 2018/2 and 2019/1, was taught with ICD/SL, which applied revised learning goals based on Fink's Taxonomy and new teaching and evaluation activities. The assessment of academic performance was based on a Likert scale to position student results in each grade score report. Statistical analysis was performed through the Kruskal-Wallis test and P-value through the Mann-Whitney U test and Fisher exact test. RESULTS: The results indicated that the treatment groups evidenced better academic performance in the summative assessment of the partial and final grades. In the treatment groups, 64% to 97% of students were in the High to Excellent segment; in comparison, this percentage in the control group was 44% to 65%. The course's rate of failure dropped from 10.9% in 2018/1 to only 1.7% in 2019/1. All the differences between the treatment and control groups were statistically significant (P < 0.0001). CONCLUSION: The use of ICD/SL improved the academic performance of students.

Endodontic Retreatment of a Maxillary Central Incisor with Two Root Canals in a Patient with Cleft Lip and Palate.

The failures in endodontic treatments are often related to anatomical variations. Some anatomical changes in anterior teeth occur in patients with cleft lip and palate. This paper aims to report the endodontic retreatment of a maxillary central incisor with two roots and two canals on a patient who presents cleft lip and palate. A male patient, 11-year-old, reported pain when chewing related to the left maxillary central incisor tooth (tooth 21) which featured a sinus tract after primary endodontic treatment. In periapical radiograph, it was observed an alteration on the anatomy of the root on the tooth 21, which featured a radiolucent area on the dental apex and had been properly endodontically treated. In cone-beam computed tomography (CBCT) images the presence of an accessory root in the palatal region was observed, that had not been prepared, or filled. Thus, the non-treated accessory canal was instrumented with the crown-down technique and filled with gutta-percha and endodontic sealer. After 1 year of follow-up, the patient presented the tooth with a normal masticatory function and no painful symptoms. Therefore, it can be concluded that the additional root canals may be present and the CBCT is an important tool to evaluate the internal root morphology. In cleft lip and palate patients, the root canals morphology should be carefully analyzed due to high prevalence of dental anomalies which may influence the success in endodontic treatment.

Micro-CT analysis of danger zone thickness in the mesiobuccal roots of maxillary first molars.

AIM: To evaluate dentine thickness from both distal ('danger zone') and mesial ('safety zone') aspects of the MB1 and MB2 canals of maxillary first molars at the furcation level using micro-CT imaging. METHODOLOGY: One hundred maxillary first molars with two canals in the MB root were selected from a Brazilian subpopulation and scanned at a resolution of 19.6 µm in a micro-CT device. From each specimen, two axial cross-sectioned images were selected at 2 and 3 mm apical to the furcation level of the MB root and evaluated for the smallest dentinal thickness. Measurements were made from the outer perimeter of the MB1 and MB2 canals towards the external root surface from both distal (danger zone) and mesial (safety zone) aspects of the root. The influence of an isthmus was also considered in the analysis, and samples were classified according to the presence or absence of an isthmus in the axial sections. Non-parametric Wilcoxon signed-rank tests were used to compare dentinal thickness between MB1 and MB2 canals with a significant level set at 5%. Colour-coded 3D models of dentine thickness throughout the MB root were created and evaluated qualitatively. RESULTS: At both levels, median dentine thickness of the MB2 canal was significantly lower in both distal and mesial aspects of the root in comparison with the MB1 canal (P < 0.01). The presence of an isthmus was not a variable that influenced dentinal thickness. Colour-coded models indicated that dentine thickness was dependent on the cross-sectional shape of the MB root. At least 50% of the sample had <1 mm of dentine thickness at the danger zone of the MB2 canal. CONCLUSIONS: Danger zones in the MB roots of maxillary first molars were not symmetrical. MB2 canals had less dentine thickness on both aspects of the root compared to the MB1 canal.

Upper molar morphology, homologies and evolutionary patterns of chinchilloid rodents (Mammalia, Caviomorpha).

Chinchilloidea are a clade of caviomorph rodents that includes seven living species, the Dinomyidae Dinomys branickii, the Chinchillidae Lagostomus maximus, two species of Chinchilla and three species of Lagidium. In addition, two extinct families are traditionally considered chinchilloids - Neoepiblemidae and Cephalomyidae. The phylogeny of the Chinchilloidea has so far not been well established and is based on partial analyses. Studying the anatomy and ontogeny of extinct and extant taxa, we propose homologies for the upper molars of Chinchilloidea for which these homologies have not been previously proposed: that is the Chinchillidae Prolagostomus, Lagostomus, Lagidium and Chinchilla, and the Neoepiblemidae Neoepiblema and Phoberomys. We identify patterns of occlusal simplification within Chinchilloidea and evaluate its importance in an evolutionary context. A phylogenetic analysis recovered Dinomyidae, Chinchillidae and Neoepiblemidae as clades. 'Cephalomyidae' have not been not recovered as a monophyletic group and 'cephalomyids' are closely related to Neoepiblemidae. Branisamys is not included within the Dinomyidae and appears to be a basal chinchilloid.

Is there a correlation between students' performance in dental anatomy and performance in operative dentistry? / ¿Existe una correlación entre el rendimiento de los estudiante de anatomía dental y el rendimiento en odontología operativa?

SUMMARY: Manual skills form only a part of the capabilities required for a future dentist. Nevertheless, they are very important components that should be tested. The aim of this study is to investigate if a correlation exists between dental students' grades in the preclinical courses and their clinical performance. Preclinical/clinical grades were collected for first, fourth, and fifth year students who graduated from the Faculty of Dentistry at the University of Jordan, Amman, Jordan, in 2016, and 2017. Two courses (Dental Anatomy and Operative Dentistry) were selected. Corre-lations comparing the practical grades of Dental Anatomy course for first year students, and the practical grades of Operative Dentistry course for the same students in fourth and fifth years. Statistically significant positive correlation was found between the soap carving grades of first-year dental students and their practical grades in Operative Dentistry course during fourth and fifth years. Also, statistically significant strong positive correlation was found between the grades of fourth-year practical Operative Dentistry and the grades of fifth-year practical Operative Dentistry. The clinical performance of dental students in their practical courses in fourth and fifth years can be predicted from their soap carving grades at their first year in Dental School.

RESUMEN: Las habilidades manuales forman solo una parte de las capacidades requeridas para un futuro dentista. Sin embargo, son componentes muy importantes que deben ser probados. El objetivo de este estudio fue investigar si existe una correlación entre las calificaciones de los estudiantes de odontología en los cursos preclínicos y su desempeño clínico. Los grados preclínicos / clínicos se obtuvieron para los estudiantes de primero, cuarto y quinto año, graduados de la Facultad de Odontología, de la Universidad de Jordania, Amman, Jordania, en 2016 y 2017. Se seleccionaron dos cursos (Anatomía Dental y Odontología Operativa). Correlaciones que comparan los grados prácticos del curso de Anatomía Dental para estudiantes de primer año y las notas de calificación prácticas del curso de Odontología Operativa para los mismos estudiantes en cuarto y quinto año. Se encontró una correlación positiva estadísticamente significativa, entre las notas de tallado de jabón de los estudiantes de primer año de odontología y sus notas de calificación prácticas en el curso de Odontología Operativa durante el cuarto y quinto años. Además, se encontró una fuerte correlación positiva estadísticamente significativa entre las notas de calificación en Odontología Operativa práctica de cuarto año y los grados de Odontología Operativa práctica de quinto año. El rendimiento clínico de los estudiantes de odontología en sus cursos prácticos en cuarto y quinto año se puede predecir a partir de las calificaciones en tallado de jabón durante su primer año en la Escuela de Odontología.

Reto de la endodoncia: conducto en "C" / Endodontics challenge: C-shaped root canal

El correcto manejo de la configuración del sistema de conductos radiculares en forma de C es un reto en la práctica endodóntica. La complejidad de este tipo de conductos hace que su diagnóstico, instrumentación y sobretodo su limpieza y obturación sea una tarea ardua en la mayoría de las ocasiones. El sistema de conductos tipo C en molares inferiores fue descripto por primera vez en 1979, por Cooke y Cox. Es una variación anatómica vista principalmente en segundos molares inferiores con una prevalencia de hasta un 31,5% en población asiática, aunque también puede ocurrir en premolares y molares, tanto superiores como inferiores. El rasgo anatómico principal de los conductos en C es la presencia de una aleta o cortina que conecta los conductos radiculares individuales. La cámara pulpar tiene un orificio que describe un arco de 180° o más. Se realiza un reporte de dos casos clínicos de conductos en C en segundo molar superior e inferior (AU)

The right management of the configuration of C-shaped root canal system is a challenge in endodontic practice. The complexity of this type of canals makes its diagnosis, instrumentation and especially its cleaning and obturation an arduous task in most of the occasions. The C-shaped canal system in mandibular molars was first described in 1979 by Cooke and Cox.It is an anatomical variation mainly seen in mandibular second molars with a prevalence of up to 31.5% in Asian population, although it can also occur in premolars and molars, both maxillary and mandibular. The main anatomical feature of the C-shaped canals is the presence of a fin or web connecting the individual root canals. The pulp chamber has an orifice that describes an arc of 180° or more. A report of two clinical cases of C-shaped canals in second maxillary and mandibular molar is presented (AU)

Entendendo a anatomia do primeiro molar inferior / Understanding first lower molar anatomy

Para entender a anatomia de cada dente precisamos estudar a sua forma e função, pois cada estrutura está diretamente ligada ao movimento da mandíbula, como altura, inclinação das cúspides e profundidade de fossa. A anatomia deve estar interligada com as condições do antagonista, estando em perfeita harmonia. Este artigo tem a função de detalhar a anatomia do primeiro molar inferior, através de fotos de dentes naturais.

To understand each tooth anatomy, we need to study its shape and function, as each structure is directly linked to the mandible movement, such as height, cusp slope and pit depth. Anatomy must be interconnected with the antagonist conditions, being in perfect harmony. This article has the objective to detail the lower first molar anatomy through photos of natural teeth.

Optimizing quality of dental carving by preclinical dental students through anatomy theory reinforcement.

Knowledge of dental anatomy is of great importance in the practice of dentistry, especially in oral rehabilitation, because without this knowledge, professional practice is not possible. Dental carving plays a major role in training dental students as it develops their manual dexterity. This randomized controlled trial aimed to evaluate the influence of didactic-theoretical reinforcement on the theoretical and practical knowledge of dental anatomy of preclinical students by examining the quality of the anatomical restorations performed by these students before and after a didactic-theoretical reinforcement. For the evaluation of theoretical knowledge, a questionnaire with closed questions about dental anatomy was used. To evaluate the effect of didactic reinforcement on dental carvings, two groups of 15 preclinical students were assessed. Experimental group (G1) received a three-hour theoretical tutoring on dental anatomy, while the control group (G2) did not. The dental carving scores obtained by the two different groups were compared using Student's t-test. Cohen's d was used to estimate the effect sizes between groups. The frequency of correct answers given for each theoretical knowledge question was compared in each group using Fisher's exact test. T-test was also used to compare the means of the two groups' final scores of theoretical evaluations. To compare these final scores obtained in both carving and theoretical tests, a principal component analysis was performed with different items assessed in each test to obtain factor loading scores and a final weighted score, where factor loadings were considered for each item. Weighted scores were compared using t-test. Also, scores obtained during the head and neck course were assessed and compared using t-test. Spearman's correlation test was used to assess the correlation between scores obtained prior to the anatomy course and scores obtained in the dental carving exercise. The theoretical evaluation revealed no significant difference between the grades (mean ± SD) of G1 (85.1 ± 6.6%) and G2 (86.2 ± 9.1%) with the grades of a baseline test that was previously obtained when students submitted to the study (P = 0.725). Regarding the tooth carving assessment, the dental carving quality by students of G1 has significantly improved, except for tooth #23 (P = 0.096). Theoretical reinforcement of dental anatomy seems to improve the students' carving performance but does not enhance their knowledge about dental anatomy. Anat Sci Educ 11: 377-384. © 2017 American Association of Anatomists.

Morphological evaluation of maxillary second molars with fused roots: a micro-CT study.

AIM: To evaluate the internal and external morphologies of fused-rooted maxillary second molars by means of micro-computed tomography (micro-CT) analysis. METHODOLOGY: A total of 100 fused-rooted maxillary second molars from a Brazilian subpopulation were divided into six groups according to the root morphology. The samples were scanned at a resolution of 19.6 µm and evaluated with regard to the external morphology of the roots, the root canal configuration, the percentage frequency of C-shaped canals and isthmuses, as well as the morphology of the root canal system at 1, 2 and 3 mm from the anatomical apex of the fused roots. RESULTS: The most prevalent root canal fusions were type 1, mesiobuccal root fused with distobuccal root (32%), followed by type 3, DB root fused with P root (27%), and type 4, MB root fused with DB root, and P root fused with MB or DB roots (21%). The prevalence of C-shaped root canal systems were 22%. Depending on the type of root fusion, the percentage frequency of isthmuses in the apical level varied from 9.3% to 42.8%, whilst the presence of apical deltas ranged from 18.5% to 57.1% of teeth. CONCLUSIONS: The root canal system of maxillary second molars with fused roots may have a high incidence of merging canals, isthmuses, apical deltas and C-shaped configurations.

Comparative accuracy of the Clearing Technique, CBCT and Micro-CT methods in studying the mesial root canal configuration of mandibular first molars.

AIMS: To compare the accuracy of the clearing technique and cone beam computed tomography (CBCT) in the assessment of root canal configurations using micro-computed tomography (micro-CT) imaging system as the reference standard. METHODOLOGY: Thirty-two mesial roots of mandibular first molars, selected on the basis of micro-CT scans (voxel size: 19.6 µm) and presenting several canal configurations, were evaluated using 2 CBCT scanners (voxels sizes: 120 µm and 150 µm) followed by the clearing technique. Two examiners analysed the data from each method and classified the anatomical configuration of the mesial canal according to Vertucci's system. Data were compared using Fisher's exact and chi-square tests. Reliability for each assessment was verified by the kappa test, and significance level was set at 5%. RESULTS: Kappa value indicated a high level of agreement between the examiners. Detection of type I configurations was significantly lower in cleared teeth (P < 0.05), whilst type II root canals were detected in all specimens by both tests (P > 0.05). In mesial roots with variable anatomical configurations, CBCT and the clearing method were significantly less accurate than the reference standard (P < 0.05). CONCLUSION: Within the tooth population studied, accuracy of identifying mesial root canal configuration was influenced greatly by the evaluation method and the type of anatomy. Detection of type I configurations in cleared teeth was significantly lower, whilst type II configurations were detected in all specimens by both methods. In mesial roots with variable anatomical configurations, neither CBCT nor clearing methods were accurate for detecting the actual root canal anatomy.

A case series of unusual root canal morphology

Aim: The thorough knowledge of tooth morphology and its variations is essential for successful endodontic treatment. Case report: This article reports an unusual root canal configuration that was detected in a maxillary central incisor with two root canals , mandibular canine with two canals and mandibular canine with two roots and root canals. Conclusions: These case reports increase the awareness of clinicians on variations in the root canal anatomy so that complete disinfection and obturation of the root canal system is possible.