Influence of implant angulation and cyclic dislodging on the retentive force of two different overdenture attachments – an in vitro study. Issue 5 (18th June 2015) - Srinivasan, Murali
Abstract: Objective: This in vitro study evaluated the influence of implant angulations on the retentive behavior of two overdenture attachments during cyclic dislodging. Methods: Models simulating a two‐implant overdenture situation were fabricated. They were divided into five groups based on their simulated implant angulations (Groups: 1 = 0°; 2 = 20°; 3 = 30°; 4 = 40°; and 5 = 60°; n = 90). Each group was further divided into two subgroups based on its attachment system (control attachment: LOCATOR ® ; test attachment: SFI‐Anchor ® ) except for group 5 which had no LOCATOR ® group. All models underwent 10, 000 insertion–removal cycles in a wet environment. Mean retentive forces were recorded. ANOVA and linear regression models were used for statistical analyses, and the level of significance was at P < 0.05. Results: The ANOVA model revealed an effect of dislodging cycles for both attachments ( P = 0.0070). The linear regression model with repeated measures revealed a significant effect of angulation within the LOCATOR ® groups (0° vs. 20°: P < 0.0001; 0° vs. 30°: P < 0.0001; 0° vs. 40°: P < 0.0001), but was insignificant within the SFI‐Anchor ® groups (0° vs. 20°: P = 0.544; 0° vs. 30°: P = 0.134; 0° vs. 40°: P = 0.254; 0° vs. 60°: P = 0.979). It further revealed a significant increase in the retentive force between the LOCATOR ® and the SFI‐Anchor ® (20°: P = 0.041; 30°: P < 0.0001; 40°: P < 0.0001), although there was no significant difference between the attachments at 0° ( P = 0.623). Conclusions: This study confirms that the retentive behavior of SFI‐Anchor ® is not influenced by implant axial inclination even at angulations of up to 60°. The SFI‐Anchor ® may therefore be particularly indicated for clinical situations with marked implant axial discrepancies.