Anatomic assessment of the anterior mandible and relative hemorrhage risk in implant dentistry : a cadaveric study

OBJECTIVES: To evaluate prevalence, size, location and content of foramina and bony canals located on the lingual side of the mandibular midline. MATERIAL AND METHODS: The prevalence and the size of midline lingual foramina and canals visible above and/or below genial spines and their distances from the mandibular base were measured in 60 dry mandibles from adult human cadavers. In addition, macro-anatomic dissections were performed on another 20 mandibles injected with red latex to investigate the vascular canal contents associated with these midline lingual foramina and canals. RESULTS: A total of 118 foramina were detected. All mandibles investigated had at least one lingual foramen at the midline above the genial spines, located at a mean height of 12.5+/-2.1 mm (SD) from the inferior border of the mandible. Macro-anatomic dissections showed a clear vascular branch entering the mandibular midline as a single vessel from a sublingual-sublingual anastomosis in 19 out of 20 mandibles studied (95%). CONCLUSION: Blood vessels in the floor of the mouth may be in close proximity to the lingual cortical plate of the mandibular midline in most cases. This implies that bleeding can occur when the mandibular cortical plate is perforated even minimally. As a consequence, the authors suggest a careful planning of implant positioning at mandibular midline, possibly opting for the use of an even number of implants in the interforaminal region, avoiding the risk of surgical trauma to the lingual cortical plate of the mandibular midline.