A CBCT study of canalis sinuosus and its accessory canals in patients attending a South African dental hospital

Abstract

The anterior maxilla is a site of frequent surgical intervention during modern dental procedures. Canalis sinuosus (CS) is a lesser-known anatomical structure residing in this region. CS is an intra-osseous canal housing the anterior superior alveolar nerve (ASAN) and artery (ASAA). The terminal portion of CS frequently gives rise to discrete intra-osseous canals, termed accessory canals (AC), which descend to terminate in various anatomical locations. Intra-operative damage to CS or it’s ACs may cause post-operative pain and paraesthesia, intra-operative haemorrhage, and failure of osseointegration of dental implants. Accurate knowledge of the anatomy of CS is needed to promote safe clinical practice. This cross-sectional, retrospective study aimed to determine the prevalence and distribution of CS and its ACs in the South African population, as well as describe its anatomical variations. The present study examined 500 cone-beam computed tomography (CBCT) scans of the anterior maxilla and recorded the prevalence, sidedness, diameter, and distribution of CS. The frequency, number, mean diameter, configuration, and point of termination of the ACs of CS was also determined. Data was collected through means of visual and metric analysis by an investigator calibrated with two experienced dental academics. Statistical analysis was performed using chi-squared or Fisher Exact tests depending on the sample size. Mean values were compared by analyses of variance (ANOVA). Median values were compared by Kruskal-Wallis tests. The level of significance was set at P = 0.05. The findings of the present study agreed with literature stating that CS should be regarded as a distinct anatomical entity. The majority of patients within the present study presented with CS bilaterally (98%). The mean diameter of CS was recorded at 1.08mm. Sex, population group, and age demonstrated no significant effect on the prevalence or sidedness of CS (P > 0.05). The ACs of CS presented as individual entities rather than bilateral pairs. Whilst the majority of subjects presented with at least one AC (58% of subjects), the ACs of CS should be considered anatomical variations, as they displayed highly variable anatomy and inconsistent prevalence. The mean diameter of the ACs in the present study was found to be less than 1.00mm. In the absence of a prevailing classification system describing the configuration of the ACs of CS, the present study classified these structures into five distinct patterns, namely; straight vertical, curved medially, curved laterally, curved distally, and other. The majority of the ACs found in the present study demonstrated a straight vertical configuration (72%). The ACs of CS in the present study terminated in five principal regions, namely; palatal, transversal, or buccal of the maxillary teeth, the mid-palatal region, and near the incisive foramen. The majority of ACs (57%) terminated palatal of the maxillary teeth. Meticulous examination of a high quality CBCT scan prior to surgical intervention of the anterior maxilla is critical to avoid intra-operative damage to CS and its ACs. Clinicians should have a thorough understanding of clinically relevant anatomy and be well-versed in the interpretation of CBCT scans to avoid unnecessary surgical complications.