Risco de lesão do ramo mandibular do nervo trigêmeo na fratura de mandíbula: um estudo anatômico / Risk of injury to the mandibular branch of the trigemal nerve in jaw fracture: an anatomical study

O nervo mandibular V3 é a terceira divisão do nervo trigêmeo, apresenta fibras motoras e sensitivas, sendo a ramificação mista deste nervo. Seus ramos eferentes são responsáveis pela motricidade dos músculos mastigatórios, inerva os músculos milo-hióideo, ventre anterior do digástrico, tensor do véu palatino e tensor do tímpano. Suas fibras aferentes são responsáveis pela sensibilidade da região inferior da face e cavidade oral, dentes inferiores, parte da língua e propriocepção da cápsula da articulação temporomandibular ATM. O objetivo deste estudo é explanar as possíveis lesões no nervo mandibular, suas ramificações e estruturas adjacentes no caso de fraturas na mandíbula, colaborando com informações detalhadas para posterior estudo de acadêmicos e cirurgiões dentistas. Foi realizada uma pesquisa de campo, exploratória e descritiva, com abordagem quanti-qualitativa, para descrição e análise do trajeto do V3 até a sua chegada no osso mandibular, assim como de estruturas que compõem a topografia adjacente a mesma utilizando uma hemiface intacta de um cadáver do sexo masculino no Laboratório de Anatomia Humana das Faculdades Nova Esperança, na cidade de João Pessoa. Devido à proximidade do nervo mandibular com o processo coronoide, fraturas nesta parte do osso mandíbula, podem ocasionar lesões no V3, além de traumas no osso temporal, e consequentemente de todo o gânglio trigeminal. Além destas, estruturas adjacentes como a glândula parótida, artérias maxilar e facial, ATM, e os nervos alveolar inferior, mentual e lingual, podem ser lesionadas em uma fratura mandibular. As lesões nestes nervos, podem resultar em redução grave da qualidade de vida e dor crônica, gerando desconfortos para o paciente. Diante do exposto fica evidente a importância de conhecer a anatomia topográfica da mandíbula e suas estruturas vasculonervosas, seu trajeto e a localização. Houve dificuldade na discussão devido à escassez da literatura em relação à temática proposta. Dessa forma, é necessário motivar novos estudos sobre a temática a fim de ampliar o conhecimento dos profissionais de saúde e estimular novas técnicas para diagnóstico precoce e melhorar os resultados terapêuticos, impactando positivamente na sobrevida de pacientes com fraturas de mandibulares(AU)

The mandibular nerve V3 is the third division of the trigeminal nerve, has motor and sensory fibers, being the mixed branch of this nerve. Its efferent branches are responsible for the motricity of the masticatory muscles, innervating the mylohyoid muscles, anterior belly of the digastric, soft palate tensor and tympanic tensor. Its afferent fibers are responsible for the sensitivity of the lower face and oral cavity, lower teeth, part of the tongue and proprioception of the capsule of the temporomandibular joint TMJ. The aim of this study is to explain the possible injuries to the mandibular nerve, its ramifications and adjacent structures in the case of mandible fractures, collaborating with detailed information for further study by academics and dentists. A field research, exploratory and descriptive, with a quantitative-qualitative approach, was carried out to describe and analyze the path of the V3 until its arrival in the mandibular bone, as well as structures that make up the topography adjacent to it using na intact hemiface of a male cadaver at the Human Anatomy Laboratory of Faculdades Nova Esperança, in João Pessoa city. Due to the proximity of the mandibular nerve with the coronoid process, fractures in this part of the mandible bone can cause injuries to the V3, in addition to trauma to the temporal bone, and consequently to the entire trigeminal ganglion. In addition to these, adjacent structures such as the parotid gland, maxillary and facial arteries, TMJ, and the inferior alveolar, mental and lingual nerves can be injured in a mandibular fracture. Damage to these nerves can result in severely reduced quality of life and chronic pain, causing discomfort for the patient. Given the above, the importance of knowing the topographic anatomy of the mandible and its vascular-nervous structures, its path and location is evident. There was difficulty in the discussion due to the scarcity of literature regarding the proposed theme. Thus, it is necessary to motivate further studies on the subject in order to expand the knowledge of health professionals and encourage new techniques for early diagnosis and improve therapeutic results, positively impacting the survival of patients with mandibular fractures(AU)

Vestibular landmarks to minimize injury to the mental nerve during transoral endoscopic thyroidectomy-vestibular approach (TOETVA) procedure: an anatomical study / Puntos de referencia vestibulares para minimizar la lesión del nervio mentoniano durante el procemiento de abordaje vestibular de tiroidectomía endoscópica transoral (TOETVA): un estudio anatómico

SUMMARY: The aim of this study is to reveal the morphometry of the mental nerve to describe a safe zone for minimizing mental nerve damage during transoral endoscopic thyroidectomy-vestibular approach (TOETVA). This study was performed on 12 cadavers. Localization of mental foramen according to teeth, distances of buccogingival sulcus-lip (BG-L), mental foramen-midline (MF-Midline), mental foramen - buccogingival sulcus (MF - BG), commissure - branching point (Cm - Br), branching point - vertical projection of branching point on lower lip (Br - LVP), vertical projection of branching point on lower lip - commissure (LVP - Cm), commissure - midline (Cm - midline), angles of mental (AM), angular (AA) and labial branches (AL) and branching patterns were recorded. Type 1 was mostly found as branching pattern in this study (45.8 %). A new branching pattern (type 9) was found on one cadaver. Mental foramen was mostly located at level of second premolar teeth. According to morphometric results of this study; supero- lateral to course of angular branch and infero-medial to course of mental branch of mental nerve on lower lip after exiting the mental foramen were described as safe zones during surgery for preserving mental nerve and its branches.

RESUMEN: El objetivo de este estudio fue revelar la morfometría del nervio mental o mentoniano para describir una zona segura y de esta manera, minimizar el daño de este nervio durante la tiroidectomía endoscópica transoral-abordaje vestibular (TOETVA). Este estudio se realizó en 12 cadáveres. Se realizó la localización del foramen mentoniano según los dientes, distancias surco gingival-labio (BG-L), foramen mentoniano-línea mediana (MF-Midline), foramen mentoniano-surco gingival (MF-BG), comisura-punto de ramificación (Cm-Br), punto de bifurcación - pro- yección vertical del punto de bifurcación en el labio inferior (Br - LVP), proyección vertical del punto de bifurcación en el labio inferior - comisura (LVP - Cm), comisura - línea mediana (Cm - línea mediana), ángulos del mentón (AM). Se registraron ramos angulares (AA) y labiales (AL) y patrones de ramificación. El tipo 1 se encontró principalmente como patrón de ramificación en el 45,8 %. Se describe un nuevo patrón de ramificación (tipo 9) encontrado en un cadáver. El foramen mentoniano se localizaba mayoritariamente a nivel de los segundos premolares. Según los resultados morfométricos, supero-lateral al curso de la rama angular e infero-medial al curso de la rama mentoniana del nervio mentoniano en el labio inferior, después de salir del foramen mentoniano, se describieron las zonas seguras, para la cirugía y preservación del nervio mentoniano y de sus ramos.

Inervación suplementaria de la mandíbula y sus Implicancias clínicas: revisión narrativa / Supplemental innervation of the mandible and it´s clinical implications: narrative review

RESUMEN: En condiciones normales, la mandíbula y sus estructuras anatómicas (dientes, musculatura, piel), son inervadas por los ramos de la tercera división del nervio trigémino (nervio mandibular), sin embargo, existen reportes que evidencian inervación suplementaria de los dientes inferiores y la zona del ángulo mandibular. Lo último podría ser responsable del fracaso del bloqueo nervioso con anestesia local. El objetivo principal de esta investigación fue revisar artículos que describen la participación de otros nervios como el milohioideo y los ramos superficiales del plexo cervical, los cuales pueden ingresar a la mandíbula a través de forámenes ubicados a lo largo de su arquitectura. Para esto, se realizó una revisión narrativa de la literatura científica, en inglés y español, desde el año 1971 hasta el año 2019, utilizando las plataformas digitales PubMed, EBSCO, Cochrane library, Scielo y Google Scholar, literatura gris y además de una búsqueda manual. Acorde a los resultados de la revisión, se confirma la existencia de fracasos de técnicas anestésicas mandibulares debido a la inervación accesoria de la mandíbula y de los dientes inferiores, donde los tres principales nervios revisados tienen incidencia en este postulado. Finalmente se plantea un orden de ejecución para realizar la infiltración de anestésico local en la mandíbula para lograr un bloqueo exitoso durante los procedimientos odontológicos que la requieran.

SUMMARY: Under normal conditions, the mandible and its anatomical structures (teeth, muscles, skin) are innervated by the branches of the third division of the trigeminal nerve (mandibular nerve), however, there are reports that show supplementary innervation of the lower teeth and the mandibular angle area. The latter could be responsible for the failure of the nerve block under local anesthesia. The main objective of this research; is to review articles that describe the participation of other nerves such as the mylohyoid nerve, and the superficial branches of the cervical plexus, which can enter the mandible through foramina located along its architecture. For this, a narrative review of the scientific literature was carried out, in English and Spanish, from 1971 to 2019, using the digital platforms PubMed, EBSCO, Cochrane library, Scielo and Google Scholar, gray literature and in addition to a search Handbook. According to the results of the review, the existence of the failures of the mandibular anesthetic techniques due to the accessory innervation of the mandible and the lower teeth is confirmed, where the three main nerves reviewed have an impact on this postulate. In conclusion, an order of execution is proposed to perform local anesthetic infiltration into the jaw to achieve a successful block during dental procedures that require it.

Determinación de la morfología del canal incisivo mandibular mediante tomografía computarizada de haz cónico (CBCT) en población de Valdivia, Chile / Determination of mandibular incisor canal morphology by cone beam computed tomography (CBCT) in a population of Valdivia, Chile

RESUMEN: El canal incisivo mandibular (MIC) es un canal neural que contiene una de las ramas inferiores del nervio alveolar inferior, llamado nervio incisivo mandibular, que puede resultar dañado durante intervenciones quirúrgicas y causar complicaciones postoperatorias. Estudio descriptivo de corte transversal. Se identificó el MIC en la imagen transversal del canino en 83 hemiarcadas. Se registró edad, sexo, hemiarcada, longitudes desde reborde alveolar vestibular de canino a MIC, cortical lingual y vestibular de canino a MIC, base mandibular de canino a MIC y ubicación del MIC (tercio lingual, medio, vestibular). Medidas se registraron en milímetros. Se aplicó test T-student para muestras independientes para variables de longitud y Chi-cuadrado para ubicación espacial del MIC, en relación con grupo etario y sexo. Se evaluó el MIC en todas las muestras (100 %). El MIC fue encontrado mayormente en el tercio medio mandibular (p <0,05). La media desde el MIC a la cortical lingual es de 5,25 mm ? 1,42 mm (derecho) y 5,24 mm ? 1,18 mm (izquierdo). La media desde el MIC a la cortical vestibular fue de 4,42 mm ? 1,29 mm (derecho) y 4,53 mm ? 1,24mm (izquierdo). La media entre centro del canal y reborde alveolar vestibular fue 18,89 mm ? 2,68mm (derecho) y 18,20 mm ? 3,06 mm (izquierdo), media desde centro del MIC al margen basal fue de 9,77 mm ? 1,93 (derecho) y 10,12 mm ? 1,92 mm (izquierdo). Se encontró mayor distribución del MIC en el tercio medio mandibular. Se identificó el MIC en el 100 % de las muestras a través de CBCT por lo que su uso como examen complementario debe ser considerado al planificar cirugías en el sector anterior mandibular.

SUMMARY: The objective of the study was to determine the morphology of the mandibular incisive canal (MIC) and its location using cone beam computed tomography (CBCT) in the population of Valdivia, Chile. Descriptive cross-sectional study. MIC was identified in the canine cross image in 83 quadrants. Age, gender, quadrants, length from buccal alveolar ridge of canine to MIC, lingual and buccal cortical of canine to MIC, mandibular base of canine to MIC, and location of MIC (lingual, middle and buccal third) were recorded. Measurements were recorded in millimeters. Independent sample Student-T test was performed to determine length variables and Chi-square test was performed to determine spatial location of MIC, in relation to age group and gender. MIC was evaluated in all samples (100 %). MIC was found mainly in the mandibular third quadrant (p < 0.05). The mean from the MIC to the lingual cortex is 5.25 mm ? 1.42 mm (right) and 5.24 mm ? 1.18 mm (left). The mean from the MIC to the buccal cortex was 4.42 ? 1.29 mm (right) and 4.53 mm ? 1.24 mm (left). The mean between the center of the canal and the buccal alveolar ridge was 18.89 mm ? 2.68mm (right) and 18.20 mm ? 3.06 mm (left), the mean from the center of the MIC to the basal edge was 9.77 mm ? 1.93 (right) and 10.12 mm ? 1.92 mm (left). A greater distribution of MIC was found in the mandibular third quadrant. MIC was identified in 100 % of the samples through CBCT, therefore, its use as a complementary examination should be considered when planning surgeries in the anterior mandibular area.

Anatomical Variation of the Auriculotemporal Nerve in Thai Cadavers / Variación Anatómica del Nervio Auriculotemporal en Cadáveres Tailandeses

SUMMARY: The auriculotemporal nerve (ATN) is an important structure lying within a limited area of an infratemporal region (ITR). The ATN is originated from the posterior branch of the mandibular division of the trigeminal nerve (V3). The ATN conveys somatosensory, secretomotor, and parasympathetic fibres of the V3 and gustatory nerve (CN IX). In literature, the most common pattern of the ATN is composed of 2 roots that encloses the middle meningeal artery (MMA). However, in many studies, it has been reported that there are many variations in ATN pattern formation. To study the variation of ATN pattern formation in Thai cadavers, 73 hemifaces from 39 Thai embalmed cadavers were dissected and the relations of the ATN to the MMA were recorded. This study concluded that there were 4 patterns observed in Thai cadavers. The common pattern is 2 roots (67.1 %), 3 roots (15.1 %), 1 root (9.6 %), and 4 roots (8.2 %). Knowledge of this variation in the ATN may be useful in understanding the symptoms of temporo-orofacial pain, paresthesia of temporomandibular joint (TMJ), possible side effects from the TMJ surgery and the efficiency of auriculotemporal nerve block for regional anesthesia of the temporomandibular joint in Thai people.

RESUMEN: El nervio auriculotemporal (NAT) es una estructura importante que se encuentra dentro de la región infratemporal (ITR). El NAT se origina en la rama posterior de la división mandibular del nervio trigémino (V3), y transmite fibras somato sensoriales, secreto motoras y parasimpáticas del V3 y del nervio gustativo (CN IX). En la literatura, se reporta que el patrón más común de NAT está compuesto por 2 raíces que contienen la arteria meníngea media (AMM). Sin embargo, en diversos estudios, se ha informado que existen múltiples variaciones en la for- mación de patrones NAT. Con el objetivo de estudiar la variación de la formación del patrón NAT en cadáveres tailandeses, se disecaron 73 estructuras hemi faciales de 39 cadáveres tailandeses y se registraron las relaciones del NAT con el AMM. En conclusión, se observaron 4 patrones en los cadáveres tailandeses. El patrón común de 2 raíces (67,1 %), 3 raíces (15,1 %), 1 raíz (9,6 %) y 4 raíces (8,2 %). El conocimiento de esta variación en el NAT puede ser útil para comprender los síntomas de dolor temporo-orofacial, parestesia de la articulación temporomandibular (ATM), posibles efectos secundarios de la cirugía de ATM y la eficacia del bloqueo del nervio auriculo-temporal para la anestesia regional de la articulación temporomandibular en Tailandeses.

Morphometry of the mandibular foramen applied to the local anesthetic block to inferior alveolar nerve in boars (Sus scrofa scrofa Linnaeus, 1758) / Morfometria do forame mandibular aplicada ao bloqueio anestésico local do nervo alveolar inferior de javalis (Sus scrofa scrofa Linnaeus, 1758)

Boars kept on commercial farms use their canine teeth as a mechanism of defense and attack in order to express their natural instincts, which could result in fractures of the teeth and jaws. Thus, utilizing local desensitization of the inferior alveolar nerve is crucial for executing therapeutic procedures in the oral cavities of those animals. Then, the goal is to carry out the morphometry of the mandibular foramen of that species, correlating it with the mandibular structures, while doing so in the safest manner for the animals. For that purpose, six hemimandibles of young-aged Sus scrofa scrofa were used, from which the proposed measurements were taken. On average, the lateral margin of the condylar process stood 142.43 mm away from the root of the lower medial incisive tooth. The longitudinal axis of the body of the mandible measured 22.3 mm at the level of the diastema that exists between the fourth lower premolar tooth and the first lower molar tooth. The mandibular foramen, from the caudal limit of the ventral margin, would be positioned at 26.6 mm from the ventral margin of the angle of the mandible in that level, 34.92 mm away from the medial margin of the condylar process, and 38.63 mm away from the dorsal limit from the caudal margin of the coronoid process. The lack of statistically significant differences, and observing that the osseous accident under scrutiny had been positioned in the ramus of the mandible, indicated that the proposed procedure should be performed from the introduction of the needle in an oblique and rostrodorsal direction for 2.0 cm, and angulated at 60º with the anatomic reference created by the medial demarcation obtained via the support of the thumb on the lateral margin of the ramus of the mandible, ventrally to the zygomatic arch, all while preserving neighboring structures and establishing an unheard-of anesthetic methodology for boars.(AU)

Javalis mantidos em criatórios comerciais utilizam os dentes caninos como mecanismo de defesa e ataque a fim de expressar seus instintos naturais, o que pode resultar em fraturas dentárias e da mandíbula propriamente dita. Desta forma, propiciar a dessensibilização local do nervo alveolar inferior é essencial para a execução de procedimentos terapêuticos na cavidade oral destes animais. Logo, objetivou-se realizar a morfometria do forame mandibular desta espécie a fim de correlacioná-lo com as estruturas mandibulares, inferindo, também, sobre a forma mais segura de realização da referida técnica nos espécimes. Para tanto, foram utilizadas seis hemimandíbulas de Sus scrofa scrofa jovens, a partir das quais foram realizadas as mensurações propostas. Em média, a margem lateral do processo condilar distanciou-se 142,43 mm da raiz do dente incisivo medial inferior; o eixo longitudinal do corpo da mandíbula mediu 22,3 mm ao nível do diastema existente entre o quarto dente pré-molar e o primeiro dente molar inferiores; e o forame mandibular, a partir do extremo caudal de sua margem ventral, posicionou-se a 26,6 mm da margem ventral do ângulo da mandíbula neste nível, 34,92 mm da margem medial do processo condilar, e 38,63 mm do extremo dorsal da margem caudal do processo coronóide. Na falta de diferenças estatisticamente significantes, e observando que o acidente ósseo estudado posicionou-se no ramo da mandíbula, indica que o procedimento proposto deva ser realizado a partir da introdução da agulha em sentido oblíquo rostroventral por 2,0 cm e angulada a 60º com o referencial anatômico criado pela delimitação medial obtida pelo apoio do dedo polegar na margem lateral do ramo da mandíbula, ventralmente ao arco zigomático, preservando as estruturas próximas e definindo-se uma metodologia anestésica inédita para os Javalis.(AU)

Características anatómicas del asa mandibular evaluada por tomografía computarizada de haz cónico / Anatomical characteristics of the mandibular loop evaluated by cone beam computed tomography

Introducción: El nervio dentario inferior es una estructura anatómica de la mandíbula, la cual presenta variaciones como el asa mandibular, ambas estructuras están relacionadas con iatrogenias con tratamientos como cirugías orales, regeneraciones óseas e implantes. El objetivo del presente estudio es evaluar las características del asa mandibular y el agujero mentoniano utilizando tomografía axial computarizada de haz cónico (CBCT) en pacientes del Postgrado de Periodoncia de la Universidad Autónoma de Nuevo León. Material y métodos: Se analizaron un total de 110 CBCT, de los cuales 61 entraron al estudio cumpliendo con los criterios de inclusión, se realizaron cortes transversales utilizando el software On Demand® para identifi car y medir el asa mandibular y localizar la posición del agujero mentoniano de ambos lados separando los grupos por género. Resultados: La prevalencia del asa mandibular fue de 32.8% de 61 CBCT que se analizaron, se observó más comúnmente en hombres y de manera bilateral, y cuando fue unilateral sólo se encontró en el lado derecho, la longitud promedio fue de 6 ± 1 mm. El agujero mentoniano se detectó en mayor porcentaje apical al segundo premolar inferior con un diámetro promedio de 3.5 ± 0.5 mm, alejándose de la raíz del diente adyacente en un promedio de 6 ± 1 mm y del borde de la mandíbula 12.5 mm ± 0.5 mm. Conclusión: Es de suma importancia identifi car las características anatómicas del asa mandibular y localizar la posición del agujero mentoniano durante la planifi cación del tratamiento para evitar complicaciones durante y después del acto quirúrgico (AU)

Introduction: The inferior dental nerve is an anatomical structure of the mandible which presents variations such as the anterior loop, both structures are related to iatrogenies with treatments such as oral surgeries, bone regenerations and implants. The aim of the present study is to evaluate the characteristics of the anterior loop and the mental foramen using cone beam computed tomography (CBCT) in patients of the Graduate Periodontics Program, School of Dentistry, Universidad Autónoma de Nuevo León. Material and methods: 110 CBCT were analyzed of which 61 entered the study fulfi lling the inclusion criteria, cross sections were made using the On Demand® software to identify and measure the anterior loop and locate the position of the mental foramen both sides separating our groups by gender. Results: The prevalence of the anterior loop was 32.8% of 61 CBCT that were analyzed, it was found more commonly in men and bilaterally, and when it was unilateral only found on the right side, the average length was 6 ± 1 mm. The mental hole was found in greater percentage apical to the second lower premolar with an average diameter of 3.5 ± 0.5 mm, moving away from the root of the adjacent tooth by an average of 6 ± 1 mm and from the edge of the mandible 12.5 ± 0.5 mm. Conclusion: It is very important to locate these anatomical structures during treatment planning and avoid complications during and after the surgical act (AU)

The mental foramen in dry human mandibles of adult South Africans: an anatomical study / El foramen mental en mandíbulas humanas secas de adultos sudafricanos: un estudio anatómico

The objective of the study was to investigate the position, position symmetry, shape and number of the mental foramen in a heterogeneous South African population. Knowledge of the precise position of MF in maxillofacial surgery is critical for an accurate local anaesthesia; and can provide a landmark in forensic or medico legal cases. Dry adult human mandibles (n = 325) were selected and classified by ancestry. The sample comprised male-to-female ratio of 1.2:1. Observations were made for the position, position symmetry, shape and number of the mental foramen. There was a substantial to perfect agreement (p < 0.001) for most observations, except for the shape of the MF on the right side of the mandible that had a fair agreement (K = 0.25; P > 0.05). PIV of the MF is shown as the most prevalent position. PIII and IV were commonly observed in males and females respectively. PII was commonly observed in the males of European descent, while PIII was observed in male African and Mixed descents and female European descents. There was no significant difference in the symmetric analysis of MF amongst male and female (p = 0.059) and between ancestry (p = 0.455). But also, an oval shape of MF was the most common across subpopulations and ancestries, with 2 (2 %) and 3 (0.46 %) of the AMFs present. This study is the first comprehensive description of the MF in the South African population, and could be very useful in forensic anthropology in the South Africa population.

El objetivo de este estudio fue investigar, en una población sudafricana heterogénea, la posición, simetría de posición, forma y número de forámenes mentales (FM). El conocimiento de la localización exacta del FM en la cirugía maxilofacial es crítico para una anestesia local precisa y puede proporcionar un punto de referencia en casos legales forenses o médicos. Se seleccionaron 325 mandíbulas humanas secas adultas y clasificadas por ascendencia. La muestra relación hombre-mujer fue de 1,2:1. Las observaciones fueron realizadas para la posición, simetría de la posición, forma y el número forámenes mentales. Se alcanzó la perfección de concordancia (p < 0,001) para la mayoría de las observaciones, a excepción de la forma intermedia en el lado derecho de la mandíbula el cual presentó un acuerdo justo (K = 0,25; p > 0,05). La PIV de la MF se muestra como la posición más prevalente. PIII y IV fueron observados comúnmente en hombres y mujeres, respectivamente. La PII se observó comúnmente en los varones de ascendencia europea, mientras que el PIII se observó en descendientes africanos y mixtos masculinos y descendientes femeninos europeos. No hubo diferencias significativas en el análisis simétrico del FM entre hombres y mujeres (p = 0,059) y entre ascendencia (p = 0,455). Una forma ovalada de FM fue la más común a través de subpoblaciones y ancestros, con 2 (2 %) y 3 (46 %) del con la presencia de un foramen mental accesorio. Este estudio es la primera descripción comprensiva del FM en la población sudafricana, y podría ser muy útil en antropología forense en la población de Sudáfrica.

Anatomical positions of the inferior dental canal and its relationship with impacted lower third molars in 18-to 29-year-old Ecuadorians

The third molars are the dental organs with the most variations in terms of their formation and time of eruption, which can cause several pathologies. The incidence of third molar impaction varies between 20% and 30%, with predominance in females. Through the inferior dental canal, goes the inferior dental nerve to innervate the molars and lower premolars. Recent studies on variations in the position of the lower dental canal have shown a low incidence of variations. Objective: To determine the prevalence of anatomical variations of the inferior dental canal in relation to impacted lower third molars, by means of digital image analysis in patients who attended the X-Ray Imaging Center in Azogues in 2016. Materials and Methods: A cross-sectional study was conducted on patients who attended the center X-Ray Imaging Center in Azogues in 2016. The following variables were analyzed: sex, age, variation of the position of the inferior dental canal in relation to the third impacted molar, the radiographic details according to the Monaco classification, and tooth position according to the Winter classification. In total, 64 radiographs were analyzed. Results: It was found that 5% of participants showed no relation of the inferior dental canal with the lower third molar, 72% had a relation of the dental canal with the third molar, and 23% presented with absence of the third molar. According to the Winter classification, the prevalence was 53% mesioangular, 18% horizontal, 19% vertical, 6% vestibuloversion, and 4% inverted. Conclusion: The third molars present high indexes of relation with the inferior dental canal in 18- to 29-year-old Ecuadorians

Topography of the inferior alveolar nerve in human embryos and fetuses: an histomorphological study

The aim of this study is to establish the position of the inferior alveolar nerve in relation to the Meckel's cartilage, the anlage of the mandibular body and primordia of the teeth, and also to trace the change in nerve trunk structure in the human prenatal ontogenesis. serial sections (20µm) from thirty-two 6-12 weeks-old entire human embryos and serial sections (10µm) of six mandibles of 13-20 weeks-old human fetuses without developmental abnormalities were studied. histological sections were impregnated with silver nitrate according to Bilshovsky-Buke and stained with hematoxylin and eosin. during embryonic development, the number of branches of the inferior alveolar nerve increases and its fascicular structure changes. in conclusion, the architecture of intraosseous canals in the body of the mandible, as well as the location of the foramina, is predetermined by the course and pattern of the vessel/nerve branching in the mandibular arch, even before the formation of bony trabeculae. particularly, the formation of the incisive canal of the mandible can be explained by the presence of the incisive nerve as the extension of the inferior alveolar nerve. It has also been established that Meckel's cartilage does not participate in mandibular canal morphogenesis.