The nasopalatine canal may show important anatomical variations, both with regard to morphology and dimensions. To avoid any potential complications during surgical procedures such as implant placement, a careful pre-operative observation is required. Cross-sectional imaging may be advocated to determine canal morphology and dimensions and to assess anterior bone width for potential implant placement buccally to the canal.

A well-defined incisive canal could be detected in the majority of spiral CT scans. Its radiographic detection remained lower than for the mandibular canal or mental foramen, but higher than for the visibility of the lingual foramen. Visualisation of the incisive canal and the occasional presence of an anterior looping, demonstrates the potential value of cross-sectional imaging of the anterior mandible for presurgical planning purposes.

FUENTES, R.; ARIAS, A.; BUCCHI, C.; SARAVIA, D. & DIAS, F. Prevalence and morphometric characteristics of the mandibular incisive canal through panoramic radiographs in a Chilean population. Int. J. Morphol., 35(3):931-937, 2017. SUMMARY: The mandibular incisive canal (MIC) is a continuation of the mandibular canal, anterior to the mental foramen, containing the neurovascular bundle of the teeth in anterior mandibular segment. The aim of this study was to calculate the prevalence and analyze the morphometric parameters of MIC in a Chilean population through digital panoramic radiographs. A cross-sectional study was performed using 500 digital panoramic radiographies of adult individuals. The prevalence of MIC was set in different sexes, age groups and proximity to teeth; in addition to the morphometric parameters of length, width (diameter) and distances of MIC to dental element and the mandibular base. General MIC prevalence was 53 % (265 cases), 49.9 % in women and 57 % in men. In the age groups, prevalence was higher in men, MIC was predominantly associated to first premolars (98.2 %-women; 90 %-men), however a relevant number (42.6 % women; 55.1 %-men) was close to the canines. The MIC length ranged from 2.6 to 18 mm (median-5 to 8 mm), the width of 0.8 to 5.4 mm (median-2 to 3 mm), the distance to other elements from 0.6 to 12 , 5 mm (medians-5 to 7 mm) and the margin of the mandible from 4.1 to 16.7 mm (median-8 to 10 mm). The length decreases in older age groups regardless of sex. Width and distance the mandibular base was larger in men compared to women.

The objective of the present study was to evaluate the presence and course of the incisive canal in the mental interforaminal region of the human mandible and to describe the occurrence of anatomical variations. Mandibles of 50 adult human cadavers were retrieved from the Department of Anatomy of the Faculty of Medicine, Katholieke Universiteit Leuven (Leuven, Belgium). Forty mandibles were edentulous, while 10 mandibles were partially dentate. Intra-oral, panoramic and tomographic imaging of the interforaminal region of the human mandible were performed. Afterwards, mandibles were sawn into vertical sections according to the respective tomographic cross-sections. The latter allowed exploration for the presence and course of an anterior prolongation of the mandibular canal. Measurements of the location of the incisive canal towards the base of the mandible were made using a digital-sliding caliper. Results indicated a well-defined incisive canal [mean (SD) inner diameter 1.8 (0.5 mm)], macroscopically observed in 96% of mandibles. The incisive canal was located on average 9.7 mm (SD 1.8 mm) from the lower cortical border and continued towards the incisor region in a slightly downward direction, with a mean (SD) distance to the lower cortical border of 7.2 (2.1) mm. It was concluded that there is an anterior intraosseous extension of the mandibular canal, denoted as the incisive canal. The latter might be considered as a true anterior extension of the neurovascular bundle. Histological and neurophysiological studies are needed to verify this hypothesis and evaluate its potential clinical implications.

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Preoperative radiographic planning for oral implant placement in the anterior mandible should therefore not only consider all esthetic and functional demands but should also pay particular attention to the anatomic peculiarities of this region to avoid any neurovascular complications.

This study aimed to analyse variations in the mandibular interforaminal morphology in an attempt to identify potential risks or contraindications for surgery, especially implant installation, in this particular region. A total of 210 spiral computer tomography (CT) examinations of patients requiring endosseous implant installation in the lower jaw were re-evaluated to explore anatomical variations in bone morphology (shape and contour), and to measure parameters concerning height, width and inclination of the bone in the symphyseal atrea. All measurements were performed on the cross-sectional reformatted images mesial to the mental foramina. A lingual concavity (with a depth of 6 +/- 2.6 mm) was observed in 2.4% of the jaws, with a remaining bone height in that area ranging from 4.2 to 11.9 mm. A clearly lingual tilted/inclined morphology was seen in 28.1% of jaws with a mean angle of 67.6 +/- 6.5 degrees, but a relatively constant width (> 8.8 mm). The remaining jaws (69.5%) showed a slight broadening in the caudal direction. The morphologic parameters were influenced neither by age nor by gender. In conclusion, mandibles with a lingual concavity or a severe slope of the lingual cortex might confer increased risks of lingual perforations during trepanation surgery or graft harvesting as well as fenestrations during implant installation. The detection frequency of such variations within the lower jaw seems to advocate a profound dissection of the lingual site and, in the case of some special treatment strategies, additional cross-sectional radiography.