Evaluation of wear and retention forces of locator attachments with different surface properties used in implant supported overdenture

Treatment of complete edentulous patients with implant-supported complete dentures prevents the lack of stability and retention, permanent bone destruction, chewing dysfunction and social problems. Locator, ball attachment, bar, magnet or telescope systems are mainly used to provide retention in implant supported complete dentures. Locator attachments are preferred because of the self-aligning feature of this type of attachments, the patient can easily fit the prosthesis with minimum wear, compensate the angles between the implant and the superstructure up to 40 degrees and prevent the fractures in the prosthesis when the interocclusal distance is short. Titanium nitride coating is often used as the base material due to its biocompatibility and mechanical properties. Nowadays, locator attachments produced from zirconia and titanium carbon nitride coated locator attachments are also used with success. The aim of this study is to determine the loss of mass and retention force of the three locator systems which are straight, 10o and 30o angled, as a result of insertion-extraction cycles in wet medium similar to the oral environment. Aluminum blocks were used to placed the matrix and implant analog. The test setup for angled test groups was changed according to the degrees. 42 samples were created for a total of six groups with 7 samples from each group. Aluminum models were axially connected to the test system (MTS 858 Mini Bionix II, Eden, Prairie, MN, USA). During the test, the samples were moistened with distilled water to simulate the oral environment. As a result, at the end of 5000 cycles, there was a loss of retention in all attachment systems, deformations in SEM findings and mass losses. Based on the 5-7 N values for the stabilization of the complete dentures on the implant, all systems showed conservative reference values. No statistically significant difference was found between the mean retention values of the angle attachments. The retention values of the 0-degree attachments were found to be significantly higher in the titanium carbon nitride coated locator.