How the initial retentive force of implant-supported overdentures can be affected with splinted and unsplinted attachments systems

Background: The aim of this study was to evaluate the retention of implant-supported overdentures with different attachment systems. Materials and Methods: In this in vitro study edentulous model with 2 Straumann implant in symphyseal region was used to make an overdenture with different attachment systems. (Dolder bar with 1 and 3 metal clips, Hader bar with 1 and 3 plastic clips, ball on bar with 2 and 4 plastic caps, Locator, Rhein plastic caps and Eleptical matrix). Retention values were recorded by universal testing machine with a cross speed of 50.8 mm/min in vertical, posteroanterior, and lateral direction. Repeated measure ANOVA and Duncan tests were used for the data analysis (α =0.05). Results: There was a statistically significant difference between the retention values of studied attachments in different dislodgment directions (P < 0.05). The highest and lowest retention were recorded for 4 balls on bar (56.71 N) and Rhein pink caps (27.89 N) in the vertical direction. Three metal clips (61.43 N) and Rhein pink cap (24.77 had the highest and lowest retention force in the posteroanterior direction. In the lateral direction, 4 balls on bar (62.68 N) and 1 plastic clip (32.27 N) showed the highest and lowest retention, respectively. Conclusion: If the higher retention force has been considered for implant-supported overdenture attachment selection, the clinician can use splinted bar or ball on bar superstructure.