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Influence of implant angulation and cyclic dislodging on the retentive force of two different overdenture attachments
Murali Srinivasan1, Martin Schimmel1,2, Isabelle Badoud3
1Division of Gerodontology and Removable Prosthodontics, University Clinics of Dental Medicine, University of Geneva, Geneva, Switzerland.
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.
