Purpose: The purpose of this study was to determine the incidence and treatment of hour glass variant mandibles for All On Four implant placement.
Materials and methods: Cone beam CAT scans were analyzed for 719 patients to determine the incidence of alveolar constriction in the mandible. Ten patients with alveolar constriction were treated over a 2-year period and retrospectively studied after 1 year in function.
Results: Of 719 mandibles studied, 28 have "hour glass" variants identified for an incidence of 3.89%. Treatment of these cases were variously done including the use of guided bone regeneration, the use of long implants, bone reduction, and angulation strategies.
Conclusions: The hour glass mandibular finding is a developmental or genetic variant that poses a significant anatomic difficulty for dental implant surgery for All On Four immediate function.
Copyright © 2011 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.