Asymmetry of the alveolar ridge in Class II maxillary defects reconstructed by an osseo-myocutaneous flap: A CBCT evaluation.

Abstract

Statement of problem: Alveolar ridge asymmetry remains in patients with Class II maxillary defects reconstructed by osseo-myocutaneous flaps, leading to esthetic and functional issues. Implant-supported fixed dental prostheses (IFDPs) might have the potential to improve facial appearance related to this asymmetry, but studies on this topic are lacking.

Purpose: The purpose of this clinical study was to determine whether IFDPs effectively improve facial appearance related to alveolar ridge asymmetry after maxillary reconstruction by using cone beam computed tomography (CBCT) based on treating the patients with IFDPs for comparable dentition defects as control.

Material and methods: Sixteen patients with Class II maxillary defects who underwent reconstruction were the study group, while 16 patients with IFDPs for comparable dentition defects were the control group. CBCT images were used to obtain 3-dimensional coordinates of landmarks and the nasolabial angle. Reference planes were established and 3 anatomic landmarks related to the alveolar ridge were defined by using a constructed coordinate plane system. Asymmetry indices of the landmarks were then calculated to assess the asymmetry of reconstructed alveolar ridge. The Welch t and Mann-Whitney tests were performed to compare the differences in 3-dimensional vectors of each landmark between the groups. Additionally, both the independent samples t and chi-squared tests were used to compare the nasolabial angle between the groups (α=.05 for all tests).

Results: Compared with patients with IFDPs for comparable dentition defects, the alveolar ridge asymmetry of reconstructed patients becomes increasingly pronounced from the anterior to the posterior zone. Quantitative analysis revealed this asymmetry was mainly because of vertical discrepancies at middle point (MP) (Δdy=3.72±4.44 mm, P=.003) and posterior point (ZB) (Δdz=4.05±7.20 mm, P=.010; Δdy=3.11±4.43 mm, P=.032). However, there was no significant difference in nasolabial angle between the 2 groups (P=.219).

Conclusions: Alveolar ridges reconstructed with osseo-myocutaneous flaps in Class II defects displayed acceptable asymmetry in the anterior zone. Bony reconstruction of anterior maxilla can support soft tissue lateral profile with the aid of IFDPs. Although posterior alveolar ridge showed mesial yawing, upward shifting, and less distal extension, IFDPs still could effectively improve the facial profile.