Does Low Gonial Angle Affect the Amount of Bone Loss Around Implant in The Posterior Mandible?

Background: The purpose of this study was to investigate whether there is a role of the low gonial angle on marginal bone resorption around the implants placed in the posterior mandible. Methods: This retrospective study, including 20 patients with 46 implants followed 36 months were inserted in the mandibular edentulous posterior area. Patients without systemic disease were included in this study. The gonial angle was measured on a panoramic x-ray; Patients with a gonial angle of more than 1250were classified as high gonial angle, and those with less than 1200 were classified as a low gonial angle group. Mesial and distal marginal bone resorption and implant angulation with the occlusal plane were measured via Image J software (National Institutes of Health; version 1.5i, USA). Independent samples t-test was used to compare measured variables between high and low gonial angle groups. Results: The mean marginal bone resorption (MBL) was 0.27±0.16 mm for the mesial side and 0.27±0.13mm for the distal side in the LGA group. In the HGA group, MBL was 0.77±0.28mm for the mesial side and 0.71±0.27mm for the distal side. There was no statistical significance between HGA and LGA groups regarding marginal bone resorption. However, implant angulation with the occlusal plane was correlated with marginal bone resorption in the HGA group. Conclusion: The result of this study is that a low gonial angle is not directly a risk factor for marginal bone resorption around the dental implant. However, implants should be placed perpendicular to the occlusal plane as possible in the HGA group.