New safety margins for chin bone harvesting based on the course of the mandibular incisive canal in CT.
OBJECTIVE
Altered pulp sensitivity of anterior lower teeth is a frequent finding following chin bone harvesting. Persistent loss of tooth sensitivity has been reported in up to 20% of the patients. The aim of this study was to evaluate current recommendations for the location of the harvest zone with respect to the course of the mandibular incisive canal (MIC), the intrabony continuation of the mandibular canal mesial to the mental foramen.


METHODS
On computed tomographic (CT) scans of 50 dentate mandibles, the MIC was located and its distance to the root apices, to the labial bony surface, and to the inferior margin of the mandible was assessed. The risk of nerve injury and the percentage of patients suitable for chin bone grafting were calculated.


RESULTS
Respecting current recommendations for chin bone grafting, the content of the MIC was endangered in 57% of the CTs. Therefore, new safety margins are suggested: the chin bone should be harvested at least 8 mm below the tooth apices with a maximum harvest depth of 4 mm.


CONCLUSIONS
Applying the new safety recommendations and proper patient selection in chin bone harvesting could reduce the risk of altered postoperative tooth sensitivity due to injury of the mandibular incisive nerve.
Pommer
Bernhard
B
Department of Oral Surgery, Bernhard Gottlieb School of Dentistry, Medical University of Vienna, Vienna, Austria. bernhard.pommer@meduniwien.ac.at
Tepper
Gabor
G
Gahleitner
André
A
Zechner
Werner
W
Watzek
Georg
G
D016025:Bone Transplantation / Q000009:adverse effects / Q000379:methods*; D002680:Chin; D020209:Cranial Nerve Injuries / Q000209:etiology* / Q000517:prevention & control; D003807:Dentin Sensitivity / Q000209:etiology / Q000517:prevention & control; D006801:Humans; D008334:Mandible / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery*; D008340:Mandibular Nerve / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D010027:Osteotomy / Q000009:adverse effects / Q000379:methods*; D011183:Postoperative Complications / Q000517:prevention & control*; D012015:Reference Standards; D012449:Safety; D020858:Tissue and Organ Harvesting / Q000009:adverse effects / Q000379:methods*; D014057:Tomography, X-Ray Computed; D014098:Toothache / Q000209:etiology / Q000517:prevention & control