Comparative evaluation of the effects of number and distribution of implants upon in vitro dislodging forces to a simulated implant supported overdenture and to examine difference between two different attachment systems: An in vitro study.

Abstract Background: Edentulous patients often face challenges with conventional mandibular complete dentures, including poor stability, retention, and compromised masticatory function, leading to discomfort and dissatisfaction. Implant-retained overdentures offer a promising solution, improving function and comfort. Two-implant-supported mandibular overdentures have become the standard of care due to their cost-effectiveness and favorable outcomes compared to fixed implant prostheses. Objective: This study aims to evaluate the impact of varying implant numbers and their distribution on dislodging forces of implant-supported overdentures, comparing the performance of ball and locator attachment systems in vitro. Methodology: An ideal mandibular stone cast was used to fabricate a denture, and implant analogs were placed in various locations of the cast. Ball and locator attachment systems were installed on the analogs. The study assessed four groups with different numbers of implants (1 to 4) across nine locations on the mandible. The overdenture was tested for dislodging forces in three directions: vertical, anteroposterior, and oblique, using a Universal Testing Machine (UTM). Results: The study found that increased implant numbers and optimal distribution of implants improved retention. Locator attachments provided superior retention under vertical dislodgement, while ball attachments performed better under oblique and anteroposterior forces. The highest retention was observed in four-implant-supported overdentures, particularly in the IV-CA/P2 region. Conclusion: The study concluded that both implant number and distribution significantly affect overdenture retention. Locator attachments were superior to ball attachments in all positions tested, particularly for vertical dislodgement. The findings suggest that the OD-1 protocol, with implants placed in the canine and second premolar positions, offers an effective and cost-effective solution for implant-supported overdentures.