Effect of Attachment Type, Maximum Occlusal Force, and Denture Deformation on Marginal Bone Loss of Two-Implant Overdentures: A Short-Term Clinical Trial

This study aimed to investigate the effect of attachment type, maximum occlusal force, denture deformation, and other confounding factors on marginal bone loss of two-implant overdentures after 1 year.Ninety edentulous patients received two implants in canine areas of the mandible using the computer-guided flapless surgical technique. Three months later, overdentures were connected to the implants with bar, resilient telescopic, and resilient stud attachments. Marginal bone loss was evaluated using standardized digitized periapical radiographs. Maximum occlusal forces were evaluated using a digital bite-force meter. Denture base deformation (denture strains, μm) was evaluated using strain gauges bonded to the polished surface of the denture at the level of the attachments. Regression analysis was adopted to find the relation between marginal bone loss and the following confounders (age, sex, mandibular bone height, period of edentulism, number of previous dentures, attachment type, maximum occlusal force, and denture strains).Telescopic overdentures showed the highest marginal bone loss and maximum occlusal force, followed by bar overdentures, and stud overdentures demonstrated the lowest values. The highest denture strains were noted with bar overdentures, followed by telescopic overdentures, and stud overdentures showed the lowest strains. Age (P = .022), mandibular bone height (P = .023), number of previous dentures (P = .004), maximum occlusal force (P ≤ .001), and denture strains (P = .048) were significantly correlated with marginal bone loss. For every 1-year increase in age, there was a decrease in bone loss by 0.3%. For every 1-mm increase in bone height, there was an increase in bone loss by 1%. For every one increase in the number of worn dentures, there was a decrease in bone loss by 4.2%. For every 10-N increase in maximum occlusal force, there was an increase in bone loss by 6.4%. For every 10-μm increase in denture strains, there was an increase in bone loss by 0.21%. Sex, time of edentulism, and attachment type did not demonstrate a significant correlation with marginal bone loss.