Distance between external cortical bone and mandibular canal for harvesting ramus graft: a human cadaver study.

Background: The aims of this study are to determine the distance of the external surface of the buccal cortical plate to the inferior alveolar canal in the mandibular molar region and to propose a safe thickness for harvesting a mandibular ramus block graft.

Methods: Thirty-four cadavers consisting of 26 dentate jaws and eight jaws in the edentulous molar region were used in this study. All mandibular ramus grafts were harvested by one investigator with the grafts extending from the external oblique ridge (EOR) and 15 mm inferiorly in the apico-coronal direction and extending from the mid-buccal aspect of the first molar to the mid-buccal aspect of the third molar in the mesio-distal direction. Measurements were made of the cortical bone thickness of the harvested ramus graft and from the cemento-enamel junction (CEJ) to the EOR, the CEJ to the mandibular border, and the CEJ to the inferior alveolar nerve (IAN).

Results: The average buccal cortical plate thickness in dentate mandibles was 2.76 +/- 0.13 mm, whereas in edentulous posterior mandibles it was 2.52 +/- 0.32 mm. The IANs were exposed in all jaws but were intact.

Conclusion: The safe thickness to harvest ramus grafts was determined to be 2.5 to 3.0 mm.