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.

Frequency and position of the mental foramen in panoramic X-rays: literature review / Frecuencia y posición del foramen mental en radiografías panorámicas: revisión bibliográfica

The mental foramen (MF), located in the body of mandible in the region below the inferior premolars, is the anatomical structure through which the mental neurovascular bundle emerges. The MF can be seen clearly in panoramic X-rays. The object of the present study was to carry out a literature review in order to identify the frequency and position of the MF in panoramic X-rays. We looked for articles in the SCiELO, Pubmed, Scopus, LILACS, Web of Science and EBSCOhost databases, for the years 2006 to 2016. The key words used were "mental foramen", "mandibular canal", "inferior alveolar nerve", "anatomy" and "panoramic X-ray". Once the articles had been selected, an analysis was made of their methodological quality; poor-quality articles were excluded. In each article the frequency and position of the MF in each hemi-mandible was analyzed. We found 82 articles, of which 20 were retained after application of the exclusion criteria. The MF was found in 4,824 hemi-mandibles (95.2 %), with greater presence on the left side (50.29 %) than the right (49.71 %). The MF is most commonly located between the apices of the inferior premolars (42.22 %), coincident with the root of the second inferior premolar (33.98 %) or distal of the root of the second inferior premolar (10.98 %). The MF is a very frequent anatomical structure. Knowledge of its location is fundamental for reducing the risk of accidents and unexpected events during clinical and surgical manoeuvres.

El foramen mental (FM), ubicado en el cuerpo de la mandíbula, inferiormente a la región de los dientes premolares inferiores, es la estructura anatómica por donde emerge el paquete vásculonervioso mental. El FM se logra visualizar con buena precisión en una radiografía panorámica. El objetivo del presente estudio fue realizar una revisión de la literatura para identificar la frecuencia y posición del FM en radiografías panorámicas. Se buscaron artículos en las bases de datos SCiELO, Pubmed, Scopus, LILACS, Web of Science y EBSCOhost, entre los años 2006 y 2016. Las palabras clave utilizadas fueron "foramen mental", "canal mandibular", "nervio alveolar inferior", "anatomía" y "radiografía panorámica". Tras la selección de los artículos se realizó un análisis de la calidad metodológica de los mismos, donde se excluyó artículos de baja calidad. Se analizó en cada artículo la frecuencia y posición del FM en cada hemimandíbula. Se encontraron 82 artículos, de los cuales quedaron sólo 20 al aplicar criterios de exclusión. El FM fue encontrado en 4824 hemimandíbulas (95,2 %), siendo el lado izquierdo donde hubo mayor presencia de forámenes (50,29 %) en comparación al lado derecho (49,71 %). El FM se localiza entre los ápices de los premolares inferiores en 42,22 %, es coincidente con la raíz del segundo premolar inferior en 33,98 %, y es distal a la raíz del segundo premolar inferior en 10,98 %, siendo éstos los más relevantes. El FM es una estructura anatómica muy frecuente, ubicada en general inferiormente a los premolares inferiores. Es una estructura de gran importancia clínica, por ello el conocimiento detallado de sus características y variaciones anatómicas es muy importante para evitar complicaciones y disminuir el riesgo de accidentes durante procedimientos clínico-quirúrgicos en la región. Además, a pesar de que la RP presenta buena precisión en la identificación del FM hay condiciones clínicas que requieren otros métodos imagenológicos para su identificación.

Morphometric relationships between the mandibular canal and the molar teeth: a tomographic analysis report / Relaciones morfométricas entre el canal mandibular y los dientes molares: reporte de un análisis tomográfico

Some dental treatments that are performed in the mandibular teeth involve manipulation of anatomical structures near the dental periapex, so it is likely to cause nerve damage due to the proximity of the inferior alveolar nerve with the apices of the mandibular teeth, mainly in the molar area. The aim of this study was to determine through Computed Tomography (CT) scan the existing distance between the mandibular canal and the anatomical structures adjacent to its path which will help to reduce the risk of injury to the inferior alveolar nerve during the different dental treatments developed in this zone. A cross-sectional study was performed where the study population consisted of 50 patients of both sexes, between 20 and 30 years with a full dentition mandible. Patients underwent a CT study of the mandible with coronal planes at 1.5 mm, the right side and the left side of each jaw were considered for the analysis and millimetric measuring was held of the distances of the mandibular canal (MC) from different anatomical structures. Subsequently, a statistical analysis was performed to obtain the mean and standard deviation of the distances between the mandibular canal and some adjacent anatomical structures. The distance from the alveolar nerve canal to the apex of the lower third molar in average was 1.49 mm on the right side and 1.69 mm on the left side, the distance between the mandibular canal and lingual cortical at the lower first molar level on average was 3.54 mm on the right side and 4.02 mm on the left side and the distance between the lingual cortical at the second molar level was on average 2.86 mm on the right side and 3.6 mm on the left side.

Algunos tratamientos dentales que se realizan en los dientes mandibulares implican la manipulación de estructuras anatómicas cercanas al periapice dental, por lo que existe la probabilidad de causar lesiones nerviosas debido a la cercanía del canal mandibular con los ápices de los dientes mandibulares, principalmente los molares. El objetivo de este estudio fue determinar a través de tomografía computarizada la distancia existente entre el canal mandibular a las estructuras anatómicas adyacentes a su trayecto lo que ayudará a disminuir el riesgo de lesiones del nervio alveolar inferior durante los diferentes tratamientos dentales desarrollados en esta zona. Se realizó un estudio transversal en donde la población de estudio estuvo compuesta por 50 pacientes de ambos sexos, entre 20 a 30 años con dentición completa en mandíbula. A los pacientes se les realizó un estudio de Tomografía Computarizada (TC) en mandíbula con cortes coronales a 1.5mm, se consideraron para el análisis el lado derecho y el lado izquierdo de cada mandíbula, y se realizó la medición milimétrica de las distancias que existen desde el CNAI a diferentes estructuras anatómicas. Posteriormente, se realizó un análisis estadístico para obtener Medias y Desviación Estándar de las distancias que existen entre el canal mandibular y algunas estructuras anatómicas adyacentes. La distancia del canal mandibular al ápice del tercer molar inferior en promedio fue de 1,49 mm del lado derecho y de 1,69 mm del lado izquierdo,la distancia entre el canal mandibular y la cortical lingual a nivel del primer molar inferior en promedio fue de 3,54 mm del lado derecho y de 4,02 mm del lado izquierdo y la distancia entre la cortical lingual a nivel del segundo molar fue en promedio de 2,86 mm del lado derecho y de 3,6 mm del lado izquierdo.

Accuracy in the diagnosis of the mental nerve loop: a comparative study between panoramic radiography and cone beam computed tomography / Precisión en el diagnóstico del bucle del nervio mental: estudio comparativo entre radiografía panorámica y tomografía computadorizada de haz cónico

Dental implant and chin osteotomy are executed on the mandible body and the mental nerve is an important anatomical limit. The aim of this research was to know the position of the mental nerve loop comparing result in panoramic radiography and cone beam computed tomography. We analyzed 94 hemimandibles and the patient sample comprised female and male subjects of ages ranging from 18 to 52 years (mean age, 35 years) selected randomly from the database of patients at the Division of Oral Radiology at Piracicaba Dental School State University of Campinas; the anterior loop (AL) of the mental nerve was evaluated regarding the presence or absence, which was classified as rectilinear or curvilinear and measurement of its length was obtained. The observations were made in the digital panoramic radiography (PR) and the cone beam computed tomography (CBCT) according to a routine technique. The frequencies of the AL identified through PR and CBCT were different: in PR the loop was identified in 42.6% of cases, and only 12.8% were bilateral. In contrast, the AL was detected in 29.8% of the samples using CBCT, with 6.4% being bilateral; Statistical comparison between PR and CBCT showed that the PR led to false-positive diagnosis of the AL in this sample. According to the results of this study, the frequency of AL is low. Thus, it can be assumed that it is not a common condition in this population.

Implantes dentales y la osteotomía de mentón son realizadas en el cuerpo mandibular y el nervio mental es un importante limite anatómico. El objetivo de esta investigación es conocer la posición del bucle del nervio mental comparando resultados entre radiografia panorámica y tomografía computadorizada de haz cónico (TCHC). Fueron analizadas 94 hemimandíbulas; la muestra de pacientes de sexo feminino y masculino con edades fluctuando entre 18 y 52 años (edad media, 35 años) seleccionados de la base de datos de pacientes de la División de Radiología de la Facultad de Odontología de Piracicaba, Universidad Estadual de Campinas; el bucle anterior (BA) del nervio mental fue evaluado según su presencia o ausencia, el cual fue clasificado como rectilíneo o curvilíneo obteniéndose el largo total del bucle; las observaciones fueron realizadas en radiografías panorámicas digitales (RP) y en TCHC de acuerdo a técnicas de rutina. La frecuencia de identificación del BA en RP y TCHC fue diferente: en la PR, el BA se identificó en un 42,6% de los casos y solo el 12,8% fue bilateral. En contraste, el BA fue detectado en el 29,8% de la muestra utilizando TCHC, con un 6,4% bilateral; la comparación estadística entre RP y TCHC muestra que la RP lleva a diagnósticos falsos positivos de la muestra de BA. De acuerdo con los resultados de este estudio, la frecuencia de BA es baja. Por este motivo se puede asumir que esta es una condición anatómica poco frecuente en la población estudiada.

A comparative evaluation of film and digital panoramic radiographs in the assessment of position and morphology of impacted mandibular third molars.

Background and Objective: Digital photo stimulable phosphor (PSP)-based radiography has many known theoretical advantages over conventional film radiography but its diagnostic efficacy has to be assessed clinically. This study compared the efficiency of conventional film-based panoramic radiographs with that of digital PSP-based panoramic radiographs in the assessment of position and morphology of impacted mandibular third molars. Materials and Methods: We selected a total of 80 impacted mandibular third molars that fulfilled the inclusion and exclusion criteria of this study. Both conventional film-based panoramic radiographs and digital PSP-based panoramic radiographs were taken of all the study samples and the teeth were later surgically removed. Conventional film-based and digital PSP-based panoramic radiographs were compared for their relative efficiencies in the assessment of impaction status, position of tooth, number of roots, root morphology, and proximity to mandibular canal of impacted mandibular third molars. An oral surgeon graded these same factors during/after surgical exploration and this assessment was considered the gold standard. The data obtained were statistically analyzed using descriptive statistics, chi-square test, and McNemar's test. Results: There was no statistically significant difference between conventional film-based radiographic assessment and digital PSP-based panoramic radiographic assessment of impaction status, position of tooth, number of roots, and proximity to mandibular canal of impacted mandibular third molars (P>0.05). However, there was significant difference between the two methods with regard to assessment of root morphology of impacted mandibular third molars (P=0.00). Interpretation and Conclusion : Conventional film-based panoramic radiographs and digital PSP-based panoramic radiographs were comparable in their accuracy in the preoperative study of impacted mandibular third molar with regard to impaction status, tooth position, number of roots, and proximity to the mandibular canal. Digital PSP-based panoramic radiographs were more accurate than conventional film-based panoramic radiographs in the assessment of root morphology of impacted mandibular third molars. Hence, we conclude that digital PSP-based panoramic radiographs can be used as an effective alternative to conventional film-based panoramic radiographs for assessment of position and morphology of impacted mandibular third molars.

[Appearance of anatomical structures of mandible on panoramic radiographs [panorex X-ray] in patients who referred to dental school of Shahid Beheshti University]

Currently panoramic radiography is used for diagnostic dental, and bone lesions, but anatomical structures also can see, for example incisive canal.At present time incisive canal position is investigated in Iranian population. Panoramic radiographs were taken by Planmeca machine from 412 patients using standard exposure. The position of patient was in compliance with standard protocol. After that mandibular incisive canal was evaluated, and data were analyzed statistically. Mental foramen, anterior loop of mental nerve and incisive canal could be observed in 84.2, 66 and 51.7% of the cases. Respectively lingual foramen wich was observed in only 6.1% of the radiographs.Gender doesn't affect on the visibility of these structures.There was a relationship between mandibular foramen and canal with age among those six landmarks. The most percent of visibility of all the landmarks was in young group and adults [third and fourth decade]. Mandibular incisive canal was considered in 51.7% of cases, it was obsereved thatthe result obtained was more than those of other researches

Bilateral bifid mandibular canal: Report of two cases.

Bifid mandibular canal is a rare anatomical variation that can be of considerable interest to a dentist. This condition can lead to complications when performing mandibular anesthesia or during surgery of the lower third molar, orthognatic or reconstructive mandibular surgery, or placement of dental implants and prosthesis; bleeding and traumatic neuroma are possible complications. Therefore, awareness of this condition is important. We report two cases of bilateral bifid mandibular canal: one in a 22-year-old male and the other in a 24-year-old female.