Anatomical study of the canalis sinuosus in Chilean individuals by cone-beam computed tomography / Estudio anatómico del canal sinuoso en individuos chilenos mediante tomografía computarizada cone-beam

SUMMARY: The canalis sinuosus (CS) is a double-curved bone canal in the anterior region of the maxilla. The CS contains a vasculo-nervous bundle consisting of the anterior superior alveolar nerve and its corresponding arteries and veins. The CS and its accessory canals (AC) have been little described in the literature and are often omitted in imaging evaluations before procedures in the region. The object of the present study was to evaluate the frequency of the CS and its AC in Chilean individuals, and to carry out a morphometric analysis of these anatomical structures by cone-beam computed tomography (CBCT) by sex, side and age range. CBCT examinations of 28 patients were studied, evaluating the presence, diameter and terminal portion of the CS. We also evaluated the presence and number of AC, and their terminal portion. The diameter of the AC was classified as greater or smaller than 1.0 mm. Non-parametric tests were used for quantitative variables and chi-squared for qualitative variables. The SPSS v.27.0 software was used, with a significance threshold of 5 %. The CS was present in all the samples analysed, generally presenting a diameter greater than 1.0 mm. Alterations were found, and the diameter could be greater depending on the segment evaluated, however it was not affected by sex, side or age range. The terminal portion of the CS is usually located adjacent to the region of the nasal cavity. The frequency of AC was very high, and the most common location was in the region of the upper central incisor; in 61.3 % of cases their diameter ?1.0 mm. The high frequency of CS and AC shows the importance of carrying out a detailed imaging study before invasive procedures in the anterior region of the maxilla.

RESUMEN: El canal sinuoso (CS) es un canal óseo que presenta doble curvatura, ubicado en la región anterior de maxila. El CS contiene un paquete vásculonervioso formado por nervio alveolar superior anterior, arterias y venas correspondientes. El CS y sus canales accesorios (CA) han sido poco descritos en la literatura y muchas veces son omitidos en evaluaciones imagenológicas previas a procedimientos en la región. El objetivo del presente estudio fue evaluar la frecuencia del CS y de sus CA en individuos Chilenos, bien como realizar un análisis morfométrico de estas estructuras anatómicas mediante tomografía computarizada cone-beam (TCCB) según sexo, lado y rangos etarios. Fueron evaluados exámenes de TCCB de 28 pacientes. Se evaluó la presencia, diámetro y porción terminal del CS. Se evaluó la presencia del CA, cantidad y porción terminal. El diámetro del CA fue clasificado en mayor o menor a 1,0 mm. Se utilizaron pruebas no paramétricas para variables cuantitativas y chi-cuadrado para variables cualitativas. Se utilizó el software SPSS 27.0, considerándose umbral de significación de 5 %. El CS estuvo presente en todas las muestras analizadas, presentando en general un diámetro mayor a 1,0 mm. El diámetro del CS sufre alteraciones pudiendo ser mayor dependiendo de la región evaluada, sin embargo no se ve afectado por sexo, lado o rangos etarios. La porción terminal de CS suele ubicarse adyacente a la región de cavidad nasal. La frecuencia de CA es muy alta, en un 61,3 % presentan diámetro ?1,0 mm, siendo la región de incisivo central superior su ubicación más común. La alta frecuencia de CS y de CA demuestra la importancia de realizarse un detallado estudio imagenológico previo a procedimientos invasivos en región anterior de la maxila.

Effectiveness of nasopalatine nerve block for anesthesia of maxillary central incisors after failure of the anterior superior alveolar nerve block technique

The purpose of this study was to assess the effectiveness of nasopalatine nerve block for anesthesia of maxillary central incisors after failure of the anterior superior alveolar nerve (ASAN) block technique. Secondarily, the possible innervation of the maxillary central incisors by the nasopalatine nerve was also investigated. Twenty-seven healthy, young adult volunteers (age: 17-26 years; gender: 9 males and 18 females) were enrolled in this study. All participants were undergraduate dental students of the University of Vale do Rio Verde de Três Corações. The volunteers had the anterior superior alveolar nerves anesthetized and a thermal sensitivity test (cold) was performed on the maxillary central incisors. The volunteers that responded positively to cold stimulus received a nasopalatine nerve block and the thermal sensitivity test was repeated. All participants were anesthetized by a single operator. Three patients presented sensitivity after both types of bilateral blocks and were excluded from the percentage calculations. In the remaining 24 patients, 16 had their maxillary central incisors anesthetized by the anterior superior alveolar block and 8 remained with sensitivity after the ASAN block. All these 8 patients had their maxillary central incisors successfully anesthetized by the nasopalatine block. In this study, 33.3 percent of the subjects had the innervation of one or both maxillary central incisors derived from the nasopalatine nerve, whilst most subjects (66.7 percent) had such teeth innervated by the anterior superior alveolar nerve. The nasopalatine nerve block was effective in anesthetizing the maxillary central incisors when the anterior superior alveolar nerve block failed.

O objetivo deste estudo foi avaliar a eficácia do bloqueio do nervo nasopalatino após falha na anestesia dos incisivos centrais superiores pelo bloqueio no nervo alveolar superior anterior (NASA). Secundariamente, investigou-se a possível inervação do incisivo central superior por ramos do nervo nasopalatino (NNP). Foram avaliados 27 voluntários saudáveis, adultos jovens (idade: 17-26 anos; sexo: 9 homens e 18 mulheres). Todos eram estudantes de Odontologia da Faculdade do Vale do Rio Verde de Três Corações. Os voluntários tiveram os nervos alveolares anteriores superiores anestesiados e em seguida foram submetidos a um teste de sensibilidade térmica nos incisivos centrais superiores. Aqueles pacientes que ainda apresentavam sensibilidade após o bloqueio do NASA receberam bloqueio do NNP e então o teste térmico foi repetido. Todos os pacientes foram anestesiados por um único operador. Três pacientes ainda apresentaram sensibilidade após ambos os bloqueios bilaterais (NASA e NNP) e foram excluídos das análises de percentagem. Dos 24 pacientes restantes, 16 tiveram seus incisivos centrais superiores anestesiados pelo bloqueio do NASA e 8 permaneceram com sensibilidade após este procedimento. Estes 8 pacientes submeteram-se ao bloqueio do NNP, o que resultou em sucesso na anestesia dos incisivos centrais superiores. Neste estudo, 33,3 por cento dos pacientes tinham a inervação de um ou de ambos os incisivos centrais superiores derivada do nervo nasopalatino, enquanto a maioria dos pacientes (66,7 por cento) tinha tais dentes inervados pelo nervo alveolar superior anterior. O bloqueio do NNP foi eficaz para anestesiar os incisivos centrais superiores, nos casos em que falhou o bloqueio do NASA.