Association between occlusal force distribution in implant overdenture prostheses and residual ridge resorption

Background This study aimed to compare residual ridge resorption (RRR) of anterior and posterior maxillary and mandibular edentulous ridges, in patients treated with mandibular implant overdentures (IOD) and compare with conventional complete dentures (CD), and to determine at each location, the association of RRR with the occlusal forces distribution and other patients’ variables. Methods The anterior and posterior RRR of IOD (6 males, 17 females) and CD (12 males, 11 females) were determined using baseline and follow-up dental panaromic radiographs (DPT), (mean intervals 4±1.8 years). The bone ratios were calculated using proportional area; anatomic to fixed reference areas, and mean difference of ratios between the intervals determined RRR. The ridge locations included anterior and posterior maxillary and posterior mandibular arches. The T-Scan III digital occlusal system, was used to record anterior and posterior percentage occlusal force (%OF) distributions. Results There were significant differences in anterior and posterior %OF between treatment groups. Two-way ANOVA showed RRR were significant for arch locations (p=0.005), treatment group (IOD versus CD) (p=0.001), however no significant interaction (p=0.799). Multivariate regression analyses showed significant association between RRR and %OF at anterior maxilla (p=0.000) and posterior mandible (p=0.023), and for treatment groups at posterior maxilla (p=0.033) and mandibular areas (p=0.021). Resorption was observed in IOD compared to CD groups, with 8.5% chance of less resorption in former and 7.8% in the latter location. Conclusion Depending on arch location, ridge resorption at various locations was associated with occlusal force distribution and/or treatment groups (implant prostheses or conventional complete dentures). This article is protected by copyright. All rights reserved.