Comparison of changes in retentive force and wear pattern of two stud attachments for implant overdentures: An in vitro study

Abstract

Context: Edentulous patients often complain about the instability of mandibular denture. To overcome that, implant-supported overdentures (IODs) have been applied as a good prosthetic option. Aims: The current study compared the changes in retentive force and patterns of surface wear of nylon rings of two stud attachments (ball and locator) upon cyclic loading. Subjects and Methods: Two implant analogs were fixed parallel to each other, 22 mm apart, in custom-made rectangular blocks for each attachment system. Ten nylon inserts of each attachment system were tested. Universal testing machine was used to measure the retentive force, and a low-value fatigue testing machine was used for cyclic loading of 2500 insertion–removal cycles. Surface changes of the components were evaluated by scanning electron microscope (SEM). Statistical Analysis Used: Paired Student's t-test was used to determine groups that were statistically significant. Results: The greatest retention loss rate, i.e., the difference between the initial retentive force and final retentive force was observed in the ball attachment (6.20 N) followed by locator attachment (3.70 N). The results were found to be statistically significant (d ≤ 0.001**). Upon SEM analysis, the nylon inserts of ball attachment revealed more surface wear compared to that of locator attachment. Conclusions: For greater retention and longer function, locator overdenture attachment should be preferred for implant overdentures over ball attachment.