Occlusal contact area, occlusal forces, and marginal bone loss around implants supporting overdentures and fixed implant-supported prostheses in patients with an atrophied mandible: A 1-year randomized clinical trial.

Abstract

Statement of problem: Prospective randomized clinical trials evaluating occlusal contact area percentage (OCA%), occlusal maximum force (MF), and marginal bone loss (MBL) around implant-supported bar overdentures compared with implant screw-retained fixed complete prostheses in participants with severely atrophied edentulous mandibles are lacking.

Purpose: The purpose of this randomized clinical trial was to assess the OCA%, MF, and vertical MBL around implant-supported bar overdentures (ISBOs) and implant-supported screw-retained fixed complete prostheses (ISFPs) in participants with severely atrophied mandibular ridges.

Material and methods: Forty participants with an edentulous atrophied mandible were enrolled, received 4 implants in the interforamina region, and were randomly divided into 2 groups (n=20). Participants in the first group (ISBO) received implant-supported bar overdentures, and those in the second group received implant-supported screw-retained fixed prostheses. The OCA% areas (using digital analysis), maximum force (using a digital occlusal force transducer), and vertical MBL around implants (using periapical radiographs) were evaluated at the insertion time of prostheses and at 6 and 12 months (T0, T6, T12). The normality of the data distribution was assessed using the 1-sample Kolmogorov-Smirnov and Shapiro-Wilk tests. Repeated measures (ANOVA), followed by the test for multiple comparisons (Tukey post hoc), were applied to identify significant differences among observation times and groups (α=.05).

Results: For the ISBO group, the highest OCA% was at T12, followed by T6 and T0. For the ISFP group, the highest OCA% was at T0, followed by T6 and T12. The ISBO group recorded a significantly higher OCA% at all observation times than the ISFP group (P<.05). Both groups had the highest maximum force (MF) at T12, followed by T6 and T0. At all observation times, ISFP recorded significantly higher MF than ISBO (P<.05). Vertical MBL significantly increased from T6 to T12 for the 2 groups (P<.05). The ISFP group showed a significantly greater vertical MBL than ISBO at T6 and T12 (P<.05).

Conclusions: The ISBO group had a better distribution of occlusal forces with the subsequent preservation of marginal bone-supporting implants than the ISFP group. However, ISBO and ISFP can both be recommended for participants with atrophied mandibular ridges.