Micro-computed tomography (micro-CT) evaluation of root canal morphology in immature maxillary third molars.

The endodontic treatment of immature permanent teeth with necrotic pulp is a significant clinical challenge. The success of regenerative endodontic procedure is highly dependent on disinfection of the root canal and an accurate anatomical knowledge of the root canal. The aim of this study was to use micro-computed tomography (micro-CT) analysis to investigate the configuration of root canals in the upper permanent third maxillary molars with incomplete root development in their coronal, apical and middle third portions. Thirty immature third permanent maxillary molars were scanned using a micro-CT system. Then, we measured the diameters and areas of the root canal in the coronal, middle and apical third of the roots. The ratio between the long and short diameter of each root canal was then calculated and the canals were divided into several groups: round, oval, long oval, flat and irregular. The round configuration was not observed in the distobuccal and mesiobuccal roots in any of their anatomical regions. Oval and long oval canals predominated in the distobuccal root. The greatest variations were observed in the mesiobuccal root, with the ribbon-shaped canal predominating in the middle region and an irregular shape in the apical region. In the coronal region of the palatal canal, the round configuration predominated; in the middle third, we observed an almost equivalent distribution between round and oval configurations; apically, the oval shape predominated. In conclusion, we observed significant complexity and variation in the morphology and configuration of root canals in immature permanent molars, thus generating additional obstacles for the success of regenerative endodontics.

The Clinical and Radiological Evaluation of Impacted Third Molar Position, Crown and Root Morphology.

OBJECTIVE: This study aimed to analyze the crown and root morphology of maxillary and mandibular third molars, and assess their position in relation to adjacent anatomical structures using clinical examination and radiographic images. MATERIALS AND METHODS: A total of 176 extracted impacted or partially impacted third molars were included in this study. Orthopantomogram images (OPG) were used to evaluate the number of roots, position, depth of impaction relative to the occlusal plane of the second molar, and angulation of maxillary and mandibular third molars. The extracted teeth were examined to determine the actual number of roots. The root morphology was classified using the Alavi classification system for maxillary third molars and the Machado classification for mandibular third molars. Additionally, the number of cusps, crown dimensions, and morphology were analyzed using digital and dental calipers. RESULTS: The extracted samples exhibited a significantly higher number of roots compared to the number assessed on OPG images (P<0.001). The majority of mandibular third molars had two fused roots (37.39%) and a five-cuspid crown (48.70%), while maxillary third molars had three fused roots (26.23%) and four cusps (42.62%). Both maxillary (60.66%) and mandibular third molars (61.74%) were predominantly vertically positioned. Regarding the depth of impaction, maxillary third molars were primarily classified as Class C (65.57%), while mandibular third molars were classified as Class B (47.83%). Differences in crown shape were observed, with maxillary crowns being mostly triangular (36.07%) and mandibular crowns being oval (38.26%). Maxillary third molars had shorter crowns compared to mandibular third molars (P<0.05). CONCLUSION: The root morphology of maxillary and mandibular third molars in the population of Bosnia and Herzegovina displays variability. Orthopantomogram imaging was found to be inadequate for accurate determination of the number of roots in third molars. The number of cusps on third molars cannot be relied upon as a predictor of the number of roots. The study's findings will have implications for dental practice, particularly for oral surgeons and restorative dentists.

Characterization of a retromolar foramen in a Chinese population: A radiographic study.

BACKGROUND: Retromolar canal (RMC) arises from the mandibular canal (MC) behind the second or third molar and travels anterosuperiorly to a retromolar foramen (RMF). RMCs and RMFs have generally been ignored in anatomical textbooks and have rarely been reviewed or studied in the anatomical and dental literature until the last decades. OBJECTIVE: This study aimed to characterize RMF in a Chinese population concerning its incidence, origin, and classification via anatomical study and periapical radiography. METHODS: 123 dry adult Chinese mandibles were collected to observe the incidence of RMFs. RMFs were determined using a steel wire 0.5 mm in diameter. The passways or origins of the retromolar canal (RMC) were determined and classified via periapical radiography. For each RMF, two dentists independently measured the diameter and its distances to the lingual cortex, the buccal cortex, and the distal edge of the last tooth (or the alveolar fossa) using a vernier caliper. RESULTS: The incidence of RMFs was 31.71%. The average RMF diameter was 0.78 ± 0.27 mm. From RMF, the distance was 4.27 ± 1.87 mm to the lingual cortex, 8.61 ± 2.23 mm to the buccal cortex, and 7.84 ± 3.87 mm to the distal edge of the last tooth (or the alveolar fossa). RMCs were classified into MC type originating from the mandibular canal and AF type originating from the alveolar fossa. The diameters of MC ones were more significant than those of AF ones. There was no apparent correlation between the existence of the third molar and the presence of an RMF. CONCLUSION: The incidence of RMFs in Chinese may be about one-third, which is a potential factor in the onset of surgery accidents. RMCs can be classified into two types by their origins. One of them is MC, which originates from the mandibular canal, and the other is AF, which originates from the alveolar fossa.

Root and canal morphology of third molar teeth.

Restorative and prosthetic considerations usually necessitates endodontic treatment of third molars in order to retain them as a functional component of the dental arch. However, the anatomy of third molars has been described as unpredictable. To date, there has been little published work on root and canal morphology of third molars, with an adequate sample size. The aim of this study was to investigate root and canal morphology of third molars. Maxillary and mandibular third molars were gathered from dental surgeries within north Jordan. Following access cavity preparation, pulp tissue was removed and root canals stained. Teeth were subject to examination after rendering them clear by immersion in methyl salicylate, and the following features evaluated: (1) number of roots; (2) number and type of root canals; (3) number and position of lateral canals; and (4) presence of inter-canal communications. Out of the examined 592 maxillary third molars, 69.9% had three roots, 10.81% had one, 9.79% had two, 9.12% had four, and 0.34% had five roots. Most had three (52.36%) and four canals (28.2%) with less frequency of two (11.48%), one (5.91%) and five canals (2.03%). Of the 639 mandibular third molars, 89.76% had two roots, 7.35% had three, 2.5% had one, and 0.47% had four roots. Most had three (55.71%) and two canals (29.42%) with less frequency of four (13.61%), one (1.09%) and five canals (0.15%). The majority of maxillary third molars had 3 roots, while the majority of mandibular third molars had two. Overall, nearly half of the maxillary and mandibular third molars had three canals. New canal configurations, not previously described in the literature nor included in Vertucci's classifications, were identified in both maxillary and mandibular third molars.

Efecto del tratamiento de la morfología oclusal con materiales para restauraciones preventivas / Effect of treating occlusal morphology with materials for preventive restorations

Introducción: las fosas y fisuras son áreas formadas por delgadas irregularidades de la capa del esmalte de la superficie oclusal. La compleja morfología en dientes posteriores es un determinante biológico asociado al desarrollo de caries. Objetivo: evaluar el efecto de diversas formas de tratar la morfología oclusal en la adaptación y penetración de materiales utilizados en restauraciones preventivas. Material y métodos: diseño experimental e in vitro. Sesenta terceros molares fueron distribuidos aleatoriamente en dos grupos: surco sin ameloplastia y con ameloplastia; además, contaban con acondicionamiento del esmalte que se subdividió en tres subgrupos: 1) sellador de fosas y fisuras, 2) adhesivo/sellador de fosas y fisuras y 3) adhesivo/ resina Flow. Resultados: los subgrupos adhesivo/sellador y adhesivo/ Flow alcanzaron mayores valores de adaptación íntima a las paredes del surco. Las diferencias fueron significativas entre los materiales (p = 0.0009). Las mayores zonas de desadaptación resultaron para el sellador sin y con ameloplastia. La penetración de los materiales fue mayor en los surcos con ameloplastia. En los surcos tratados con ameloplastia, el adhesivo/Flow reveló el mayor porcentaje de penetración y la mejor adaptación a las paredes del surco. Conclusiones: la penetración del material está positivamente correlacionada con la profundidad del surco. El sellador con y sin ameloplastia mostró pobre adaptación a las paredes del surco (AU)

Introduction: pits and fissures are areas formed by fine irregularities in the enamel layer of the occlusal surface. The complex morphology in posterior teeth are biological determinants associated with the development of caries. Objective: to evaluate the effect of various ways of treating occlusal morphology on the adaptation and penetration of materials used in preventive restorations. Material and methods: experimental design, in vitro. Sixty third molars were randomly distributed into two groups: groove without ameloplasty and with ameloplasty, with enamel conditioning with three subgroups: 1) pit and fissure sealer, 2) adhesive/pit and fissure sealer, 3) adhesive/resin flow. Results: the adhesive/sealant and adhesive/flow subgroups reached higher values of intimate adaptation to the furrow walls. The differences were significant between the materials (p = 0.0009). The largest areas of maladjustment were found for the sealant without and with ameloplasty. The penetration of the materials was greater in the grooves with ameloplasty. In the grooves treated with ameloplasty, the adhesive/flow revealed the highest percentage of penetration and the best adaptation to the walls of the groove. Conclusions: the penetration of the material is positively correlated with the depth of the furrow. The sealant with and without ameloplasty showed poor adaptation to the sulcus walls (AU)

Evaluation of multi-task learning in deep learning-based positioning classification of mandibular third molars.

Pell and Gregory, and Winter's classifications are frequently implemented to classify the mandibular third molars and are crucial for safe tooth extraction. This study aimed to evaluate the classification accuracy of convolutional neural network (CNN) deep learning models using cropped panoramic radiographs based on these classifications. We compared the diagnostic accuracy of single-task and multi-task learning after labeling 1330 images of mandibular third molars from digital radiographs taken at the Department of Oral and Maxillofacial Surgery at a general hospital (2014-2021). The mandibular third molar classifications were analyzed using a VGG 16 model of a CNN. We statistically evaluated performance metrics [accuracy, precision, recall, F1 score, and area under the curve (AUC)] for each prediction. We found that single-task learning was superior to multi-task learning (all p < 0.05) for all metrics, with large effect sizes and low p-values. Recall and F1 scores for position classification showed medium effect sizes in single and multi-task learning. To our knowledge, this is the first deep learning study to examine single-task and multi-task learning for the classification of mandibular third molars. Our results demonstrated the efficacy of implementing Pell and Gregory, and Winter's classifications for specific respective tasks.

Comparison Between Primary and Secondary Method of Closing Surgical Wound After Tooth Extraction: A Split-Mouth Study

ABSTRACT Objective: To compare and assess the primary and secondary closure techniques following extraction of impacted third molars for post-operative complications. Material and Methods: In total, 30 patients ranging between 18-30 years of age and of either sex who had bilaterally impacted mandibular third molars were randomly selected. Split mouth study method was used so that the participants served as their own control. Group 1 consisted of primary closure of left mandibular impacted third molars and Group 2 consisted of secondary closure of right mandibular impacted third molars. Basement evaluations were recorded for each patient along with subjective and objective evaluations for postoperative 7 days. Data analysis was carried out by SPSS 17.0 software using Mann-Whitney U test, Wilcoxon matched-pairs test and t-test. A p-value ≤ 0.05 was assigned as statistically significant. Results: When compared to group 1, group 2 revealed statistically less pain and swelling following the secondary closure of wound from day 1 to 7. There was a significant improvement in mouth opening in Group 2 at day 1 (p=0.0005) and at day 7 (p=0.00001). Conclusion: Secondary wound closure after disimpaction of mandibular third molar results in better postoperative recovery than primary closure.

Forensic Validity of the Third Molar Maturity Index (I 3M) for Age Estimation in a Russian Population.

The aim of this cross-sectional study was to test the accuracy of the third molar maturity index (I 3M) cut-off value (0.08) to distinguish between individuals above and below the adult age of legal responsibility (18 years) in a Russian population. A sample of 571 digital panoramic radiographs of healthy Russian minors and young adults (363 females and 208 males), aged between 14 and 24 years, was evaluated. The lower left third molars were analyzed by applying the cut-off value of 0.08 determined by Cameriere et al. (2008). Lin's concordance correlation coefficient (ρ c) and Cohen's kappa coefficient (κ) showed that repeatability and reproducibility are high for both intra- and interobserver errors. The I 3M value decreased with age in both sexes. Age distribution gradually decreases as I 3M increases in both girls and boys. In the male group, molar maturity stages 0-0.04, 0.04-0.08, 0.08-0.3, 0.3-0.5, and 0.9-1.4 were reached slightly earlier than in the female group. The results demonstrated that sensitivity is 0.96 in boys and 0.93 in girls; associated specificity values were both 0.98. The cut-off value of I 3M is statistically robust and thus valid for forensic application in a Russian population to determine whether or not a subject has reached 18 years of age. Finally, we compared our results with those of other studies in which the same I 3M cut-off value was tested on different populations. The method is novel as it is reliable and easily reproducible, thus ensuring a universal way of comparing the results obtained (based on a cut-off value) among many populations, in order to develop an ever-increasing database.

Growth and development of the third permanent molar in Paranthropus robustus from Swartkrans, South Africa.

Third permanent molars (M3s) are the last tooth to form but have not been used to estimate age at dental maturation in early fossil hominins because direct histological evidence for the timing of their growth has been lacking. We investigated an isolated maxillary M3 (SK 835) from the 1.5 to 1.8-million-year-old (Mya) site of Swartkrans, South Africa, attributed to Paranthropus robustus. Tissue proportions of this specimen were assessed using 3D X-ray micro-tomography. Thin ground sections were used to image daily growth increments in enamel and dentine. Transmitted light microscopy and synchrotron X-ray fluorescence imaging revealed fluctuations in Ca concentration that coincide with daily growth increments. We used regional daily secretion rates and Sr marker-lines to reconstruct tooth growth along the enamel/dentine and then cementum/dentine boundaries. Cumulative growth curves for increasing enamel thickness and tooth height and age-of-attainment estimates for fractional stages of tooth formation differed from those in modern humans. These now provide additional means for assessing late maturation in early hominins. M3 formation took ≥ 7 years in SK 835 and completion of the roots would have occurred between 11 and 14 years of age. Estimated age at dental maturation in this fossil hominin compares well with what is known for living great apes.

The role of occlusal support and lower third molars in mandibular angle and condylar fractures / A bölcsességfog és az occlusio szerepének vizsgálata a mandibulaangulus és -condylus töréseiben

INTRODUCTION AND AIM: The aim of our study was to investigate the influence of the occlusal support, and mandibular third molars on mandibular angle and condylar fractures. METHOD AND RESULTS: Patients with unilateral and isolated angle or condylar fractures were included in this retrospective, cross-sectional study. Data was collected from patient records and panoramic x-rays. The predictor variables included the type of occlusal support and the presence or absence of third molars. The outcome variable was angle or condylar fracture, while other predictor variables included demographic factors. Bivariate (χ2 test) and logistic regression analyses were conducted to investigate the associations between variables and the outcome. 43 angle (mean age: 29.9 ± 12.8 years; 98.4% male) and 37 condylar (mean age: 46.8 ± 20.2 years; 62.2% male) fracture cases were included in this study. Bilateral occlusal support was present in 81.4% of angle fracture group and in 51.3% of condylar fracture group (p<0.001). In the case of bilateral occlusal support, an odds ratio (OR) of 4.2 was found for angle fractures (p<0.006). A third molar was present in 86% of the angle fracture group and in 43.2% of the condylar fracture group (p<0.001). The presence of a third molar exhibited an odds ratio of 8.1 for the angle fractures (p<0.001). When bilateral occlusal support and third molar were present simultaneously, the risk was 15.9 times higher for an angle fracture (p<0.001). CONCLUSION: The presence of occlusal support and/or third molars was significantly associated with angle fractures, however, the absence of occlusal support and/or third molars significantly correlated with condylar fractures. Orv Hetil. 2020; 161(28): 1166-1174.

Is third molar agenesis an anomaly or just a sign of variation? Prevalence and manner of presentation of this condition in a sample from the Metropolitan Region of Chile / ¿Es la agenesia del tercer molar una anomalía o simplemente un signo de variación? Prevalencia y forma de presentación de esta condición en una muestra de la Región Metropolitana de Chile

Agenesis of permanent teeth is the most frequent dental anomaly. The most affected tooth is the third molar (M3), and its congenital absence poses interesting questions from a clinical and evolutionary perspective. M3 agenesis can occur isolated or as part of syndromes. Researchers have reported prevalences that vary largely among populations, between 5 % and 56 %, with a mean prevalence of 22.6 %. Previous Chilean studies, mainly in Northern populations, have determined a prevalence between 19.8 % and 26.7 %. The aim of this work was to assess the prevalence of M3 agenesis and to characterize its presentation in a sample from Santiago, the largest to date in a M3 agenesis prevalence study in Chile. In this study, 535 panoramic radiographies and clinical histories of patients from the Dental Clinic of the Universidad de Chile were used to determine prevalence and distribution according to sex, affected tooth, and location (left or right; maxilla or mandible). The Chi-square test was used to assess statistical significance in distribution. The calculated M3 agenesis prevalence was of 12.89 %. No statistically significant differences were found between sexes, sides or location within the jaws. The agenesis of one third molar was more common, then two, three and finally of all the third molars. The prevalence of M3 agenesis in the sample is 12.89 %, with a random manner of presentation. We propose that as it currently stands, M3 agenesis should be considered an anatomical variation rather than a developmental anomaly.

La agenesia de dientes definitivos es la anomalía dental más común. El diente más afectado es el tercer molar (M3), y su ausencia congénita plantea preguntas interesantes desde una perspectiva clínica y evolutiva. La agenesia de M3 puede ocurrir de manera aislada o asociada a síndromes. Estudios a nivel mundial reportan una prevalencia variable entre poblaciones: 5 % a 56 %, con una prevalencia media del 22,6 %. Estudios chilenos anteriores, principalmente en poblaciones del norte, han determinado una prevalencia entre 19,8 % y 26,7 %. El objetivo de este trabajo fue determinar la prevalencia de agenesia de M3 y caracterizar su presentación en una muestra de Santiago, la más grande hasta la fecha en un estudio de prevalencia de agenesia de M3 en Chile. Se utilizaron 535 radiografías panorámicas y antecedentes de pacientes atendidos en la Clínica Odontológica de la Universidad de Chile para evaluar la prevalencia y modo de presentación de la agenesia de M3. Se analizó su distribución según ubicación, sexo y simetría, mediante test estadístico Chi-cuadrado. Se calculó una prevalencia de agenesia de M3 de 12,89 %, sin un patrón claro ni estadísticamente significativo en su distribución. Fue más común la agenesia de un tercer molar, luego de dos, tres y finalmente de todos los terceros molares. La prevalencia de agenesia en una muestra de la Región Metropolitana es de 12,89 % y su distribución es aleatoria según la ubicación, sexo y simetría. Se propone que esta condición actualmente debiera considerarse como una variación anatómica más que a una anomalía del desarrollo.

Factors associated with spontaneous angular changes of impacted mandibular third molars as a result of second molar protraction.

INTRODUCTION: This study aimed to identify significant factors affecting the spontaneous angular changes of impacted mandibular third molars as a result of second molar protraction. Temporary skeletal anchorage devices in the missing mandibular first molar (ML-6) or missing deciduous mandibular second molar (ML-E) with missing succedaneous premolar spaces provided traction. METHODS: Forty-one mandibular third molars of 34 patients (10 male and 24 female; mean age 18.3 ± 3.7 years) that erupted after second molar protraction were included in this study. They were classified into upright (U) and tilted (T) groups. Linear and angular measurements were performed at the time of treatment initiation (T1) and of ML-6 or ML-E space closure (T2). Regression analyses were used to identify significant factors related to third molar uprighting. RESULTS: Nolla stage (odds ratio [OR] 4.1), sex (OR 0.003 for male), third molar angulation at T1 (OR 1.1), missing tooth space (OR 0.006), rate of third molar eruption (OR 23.3), and rate of second molar protraction (OR 0.2) significantly affected third molar uprighting. Age, third molar angulation at T1, rate of third molar eruption, and rate of second molar protraction were significant factors for predicting third molar angulation at T2. CONCLUSIONS: Available space for third molar eruption before and after second molar protraction is not associated with uprighting of erupting third molars. Older patients whose third molars are in greater Nolla stage, are in a more upright position at T1, and have a greater eruption rate have a greater chance for third molar uprighting. Alternatively, an increase in second molar protraction rate results in mesial tipping of the third molars.

Anatomical relation of third molars and the retromolar canal.

The study was designed to assess, by direct anatomical observations and cone-beam computed tomography (CT), the prevalence of a retromolar canal and foramen in relation to the mandibular third molar in dry human mandibles. Dry mandibles from European skeletons (n=89) were observed directly and after cone-beam CT scanning (Newtom VGI evo). The following variables were assessed: the presence of a retromolar foramen and canal; the presence of a third molar, and orientation of the third molar. From the total of 89 mandibles selected, 73 showed a retromolar foramen (49 of which were bilateral). A retromolar canal was identified in 64 mandibles based on cone-beam CT assessment, with a total of 101 canals, including 74 that were bilateral. A total of 112 hemimandibles contained a third molar. Orientation of the third molar did not seem to indicate the presence of retromolar foramina or canals. A similar prevalence of retromolar canals was found for both vertically (41/79) and mesially (17/33) orientated third molars. A retromolar foramen and canal were present in most mandibles, with more than half being bilateral. We were unable to confirm a potential relation between the retromolar foramen and canal on the one hand, and the orientation of the third molar on the other.

Three-Dimensional Assessment of Crown Size and Eruption Space for Developing Third Molars: Data Collection Techniques Based on Cone-Beam Computed Tomography (CBCT).

Third molar development and eruption are two related areas of major interest in dental research into the etiology of "wisdom tooth" impaction. Third molars are not only an excellent model for studying dental development but also of fundamental clinical importance because they are very frequently impacted. Because the third molar is located in the distal-most region of the oral cavity, clinical access is relatively challenging. With the increasingly widespread use of cone-beam computed tomography (CBCT) in dentistry, studies and measurements of the third molar and its eruption area have become considerably easier to do. Here we present a novel CBCT-based measurement methodology we developed for our recent investigations that we hope will also be useful for the broader dental research community.

Dental age assessment on panoramic radiographs: Comparison between two generations of young Finnish subjects.

OBJECTIVE: To analyse the accuracy of a meta-analysis-based dental age assessment (DAA) method in Finnish paediatric patients and to compare the dental development between two generations of Finnish children. METHODS: Panoramic radiographs of Finnish Caucasian healthy children from two generations (early: born 1981-1984; subsequent: born 1996-2008) were analysed. All developing teeth on the left maxilla and mandible as well as the third permanent molars were analysed following Demirjian's classification. For each patient, dental age was calculated and compared with chronological age. Dental maturation patterns between the two groups were compared. RESULTS: The study included 200 Finnish Caucasian healthy children from two generations (early: aged 7-13 years; subsequent: aged 6-15 years). In the early generation, DAA underestimated the chronological age by a mean of 3.15 years. The underestimation was only 0.11 years in patients < 10 years, but 3.86 years in patients ≥ 10 years. In the subsequent generation, the dental age was overestimated by a mean of 0.34 years; by 0.40 years in patients < 10 years and by 0.08 years in patients ≥ 10 years. CONCLUSIONS: The present DAA method is applicable to current Finnish children. Differences in dental development between two generations of Finnish children were detected.

Effect of posterior space discrepancy and third molar angulation on anterior overbite.

INTRODUCTION: In this study, we aimed to determine the effect of maxillary and mandibular posterior space discrepancies and third molar angulations on the overbite. METHODS: Pretreatment lateral cephalograms of 131 subjects were analyzed. The sample included 83 open-bite and 48 deepbite subjects. A multiple regression analysis was used to evaluate the influence of maxillary and mandibular posterior space discrepancies and third molar angulations (predictor variables) on overbite. Correlations between posterior space discrepancy and third molar angulation, and correlations between predictor variables and dental angulation and height of posterior teeth and incisors were evaluated with the Pearson correlation coefficient. Subgroups with accentuated negative overbite and deepbite (27 open-bite, 37 deepbite) were compared with t tests. RESULTS: The multiple linear regression analysis showed a positive association of the mesial angulation of the mandibular third molar with overbite. Posterior space discrepancy was negatively associated with posterior teeth mesial angulation and dentoalveolar height. However, these associations were weak, with no clinically significant implications. The deepbite subgroup showed significantly greater mesial angulation of the mandibular third molars than did the open-bite subgroup. CONCLUSIONS: There was no clinically significant effect of posterior space discrepancies and third molar angulations on overbite and dental angulation and height of posterior teeth and incisors.

Correlação entre a mineralização dos terceiros molares e a idade cronológica por três métodos / Correlación entre la mineralización del tercer molar y la edad cronológica por tres métodos / Correlation between third molar mineralization and chronological age by three methods

Introdução: os estágios de mineralização dentária têm sido utilizados em diversos estudos para a estimativa de idade, apresentando confiabilidade nos resultados. Objetivo: correlacionar a mineralização dos terceiros molares e a idade cronológica pelos métodos de Nolla, Demirjian e Nicodemo, Moraes e Médici Filho numa amostra populacional do nordeste brasileiro. Métodos: de um universo de 1 205 radiografias panorâmicas digitais, foram selecionadas 297 imagens de pacientes atendidos rotineiramente em um serviço de Radiologia Odontológica privado. Todas as imagens foram avaliadas em ambiente escurecido por três examinadores calibrados, utilizando as classificações de Nolla (1960), Demirjian (1973) e Nicodemo, Moraes e Médici Filho (1974). Os dados numéricos foram resumidos através das estatísticas descritivas de locação e dispersão. Para análise estatística foi ajustado um modelo de regressão linear simples considerando a idade como variável resposta. Para os testes, foi adotado o nível de significância de 5 porcento ciento. Resultados: o desenvolvimento dos terceiros molares foi mais adiantado no sexo masculino na maioria dos estágios, para os três métodos. Nos dentes superiores, o dimorfismo sexual foi mais evidente no estágio 7 de Nolla (diferença de 16,34 m no dente 18 e 14,43 m no dente 28). Nos dentes inferiores, as maiores diferenças ocorreram: no estágio 6 de Nolla (diferença de 13,92 m no 38 e 10,46 m no 48) e estágio 5 de Nicodemo (diferença de 16,23 m mais elevado no elemento 38 e 9,9 m no 48). O desenvolvimento dos dentes terceiros molares dos lados direito e esquerdo apresentou-se semelhante, contudo os dentes superiores apresentaram-se mais adiantados que os inferiores. O presente estudo permitiu o desenvolvimento de fórmulas baseadas em regressões lineares simples utilizando os três métodos propostos, possibilitando, assim, estimar a idade cronológica dos indivíduos da amostra. Conclusão: houve correlação do desenvolvimento dentário dos terceiros molares com a idade cronológica pelos três métodos(AU)

Introducción: las etapas de mineralización de los dientes se han utilizado en varios estudios para estimar la edad, lo cual ha mostrado resultados fiables. Objetivo: correlacionar la mineralización de los terceros molares y la edad cronológica por los métodos de Nolla, Demirjian y Nicodemo, Moraes y Medici Filho en una muestra de población del nordeste de Brasil. Métodos: a partir de un universo de 1 205 radiografías panorámicas digitales, se seleccionaron 297 imágenes de pacientes tratados de forma rutinaria en un servicio de radiología dental privada. Todas las imágenes fueron evaluadas en cuarto oscuro por tres examinadores calibrados, utilizando los métodos de Nolla (1960), Demirjian (1973) y Nicodemo, Moraes y Medici Filho (1974). Los datos numéricos se resumieron utilizando estadística descriptiva del contrato de arrendamiento y la dispersión. El análisis estadístico se ajustó un simple modelo de regresión lineal, considerando la edad como variable de respuesta. Para las pruebas, se adoptó el nivel de significación del 5 pr ciento. Resultados: el desarrollo de los terceros molares fue más temprano en los varones en la mayoría de las etapas, por los tres métodos. En los dientes superiores, el dimorfismo sexual fue más evidente en la etapa 7 de Nolla (diferencia de 16,34 m en el diente 18 y 14,43 m en el diente 28). En los dientes inferiores, las mayores diferencias ocurrieron: en la etapa 6 de Nolla (diferencia de 13,92 m no 38 y 10,46 m no 48) y etapa 5 de Nicodemo (diferencia de 16,23 m más elevado en el elemento 38 y 9,9 m no 48). El desarrollo de los dientes terceros molares de los lados derecho e izquierdo se presentó semejante, sin embargo los dientes superiores se presentaron más adelantados que los inferiores. Este estudio permitieron el desarrollo de formulaciones a base de regresiones lineales usando los tres métodos propuestos, permitiendo estimar la edad cronológica de los individuos en la muestra. Conclusiones: se observa una correlación de desarrollo de los dientes terceros molares con la edad cronológica por tres métodos(AU)

Introduction: dental mineralization stages have been used in several studies to estimate age, and the results obtained have been found to be reliable. Objective: correlate third molar mineralization and chronological age using the methods developed by Nolla, Demirjian, and Nicodemo, Moraes and Medici Filho in a population sample from Northeast Brazil. Methods: of a total 1 205 digital panoramic radiographs, 297 were selected of patients routinely seen in a private dental radiology service. All the images underwent darkroom evaluation by three qualified examiners using the methods developed by Nolla (1960), Demirjian (1973), and Nicodemo, Moraes and Medici Filho (1974). Numerical data were summarized by location and dispersion descriptive statistics. For statistical analysis a simple linear regression model was adjusted which considered age as response variable. A significance level of 5 percent was adopted for the tests. Results: third molar development occurred earlier in males in most stages by the three methods. In upper teeth, sexual dimorphism was more evident in Nolla stage 7 (difference of 16.34 m in tooth 18 and 14.43 m in tooth 28). In lower teeth, the greatest differences occurred in Nolla stage 6 (difference of 13.92 m in 38 and 10.46 m in 48) and Nicodemo stage 5 (difference of 16.23 m higher in tooth 38 and 9.9 m in 48). Third molar development was similar on the right and left sides, but greater in upper teeth than in lower teeth. The study allowed development of linear regression formulas based on the three methods proposed, making it possible to estimate the chronological age of the individuals in the sample. Conclusions: the three methods found a correlation between third molar development and chronological age(AU)

Outcome of Autotransplantation of Mature Third Molars Using 3-dimensional-printed Guiding Templates and Donor Tooth Replicas.

Autotransplantation exhibits a number of advantages compared with other treatment options (ie, dental implants or fixed partial prostheses), such as greater resistance to occlusal loading, maintenance of the periodontal ligament and surrounding bone, and the potential for better esthetics. The aim of this study was to determine clinical outcomes for autotransplanted teeth with complete root formation using 3-dimensional-printed guiding templates and tooth replicas. Twenty-seven third molars with completely formed roots were autotransplanted. Each donor tooth and recipient site were examined clinically and radiographically (periapical radiographs). A selective cone-beam computed tomographic scan was taken of each donor tooth and recipient site. The images of the selected donor teeth were segmented and saved as stereolithography files. Similar to virtual planning of dental implants, correct angulation, rotation, and accurate positioning of the donor teeth were predefined using the stereolithography files. According to the virtually defined positions and dimensions of the donor teeth, 3-dimensional guiding templates and donor tooth replicas were printed. All autotransplantations were performed according to 1 treatment protocol and surgical technique. In 22 of the 24 transplanted teeth, no inflammation occurred during the healing period. At 2 years, no pathologic radiolucency or tooth resorption was observed in the 22 donor teeth. The autotransplanted teeth fulfilled the success criteria in 22 cases for a 91.7% success rate. Digital planning could potentially provide an accurate alternative to current autotransplantation techniques.

Root and root canal variations of the human maxillary and mandibular third molars in a Chinese population: A micro-computed tomographic study.

OBJECTIVES: To investigate the anatomical variations of the root and root canal configuration of the human third molars. DESIGNS: A total of 130 maxillary and 130 mandibular third molars were collected from a native Chinese population. All teeth were scanned by micro-computed tomography. After 3D reconstruction, the root and canal morphology of each tooth was examined both qualitatively and quantitatively. RESULTS: For maxillary molars, a single fused root (67 cases, 51.5%) and a single root canal system (64 cases, 49.2%) was most common root/canal form; the typical three-rooted molars were detected only in 33 cases (25.4%), and the secondary MB canals were detected only in 9 molars (6.9%). For mandibular molars, 62 teeth were single-rooted (47.7%) and 42 had a single root canal system (32.3%); 20 singled-rooted and 60 double-rooted molars exhibited independent mesial and distal root canal systems (61.5%), and the type 1-1 canal was the most common configuration for mesial (57 cases) and distal (81 cases) root canal systems. C-shaped canals were detected in 11 maxillary and 36 mandibular single-rooted molars. The mean root surface area, root and crown volume of mandibular third molars were significantly higher than the maxillary third molars (P < 0.01). CONCLUSION: The root canal system of the third molars may exhibit several anatomic variations. Whereas in most of cases, the degree of the canal differentiation was at a low level, and the canal form was not complicate.

Bifurcation of the inferior dental nerve canal: an anatomical study.

The aims of this study were to find the incidence of bifurcation of the inferior dental nerve (IDN) canal, to describe the characteristics of this variant, and to examine the sensitivity and specificity of dental panoramic tomography to identify it. We classified bifurcations by size and position relative to the main canal and the lower third molar using cone-beam computed tomography (CT) and dental panoramic tomography. In our study of 281 patients, 106 (38%) had bifurcations, and in one quarter, these were classified as large accessory canals. Bifurcations were most commonly found posterior to the lower third molar (n=64, 57%) or within 2mm of the roots of the third molar (n=40, 38%). The sensitivity and specificity of dental panoramic tomography to identify all bifurcations was 11% (95% CI: 5.67 to 17.97) and 91% (95% CI: 85.58 to 94.68), respectively; this was 33% (95% CI: 15.63 to 55.32) and 94% (95% CI: 90.34 to 96.50), respectively, for large bifurcations. Our use of cone-beam CT suggested an incidence of bifid canals of 38%, with a variation in size and distribution in relation to the lower third molar. It also showed that the sensitivity of panoramic radiography to identify them was poor.