Aim: This study aimed to evaluate of different degrees of mesial implant inclinations on retention of locator attachments used for 2-implant retained mandibular overdentures.
Materials and Methods: Four completely edentulous mandibular acrylic resin models were duplicated from a completely edentulous stone model. Silicone soft liner was used to simulate natural mucosa.Two implants were inserted in the canine area bilaterally with the following degrees of mesial implant inclinations 10, 20, 30. For each degree of implant inclination retention (vertical dislodging forces). Mandibular experimental overdenture were constructed over the model and connected to the model with Locator attachment. The universal testing machine was used to apply vertically oriented 4 points tensile loads on a metal plate attached to the model with 4 metal chains until the attachments separated from the abutments. Maximum load needed to dislodge the experimental overdenture from the mandibular test model (retentive force) were calculated.
Results: For initial retentive forces and retentive forces after repeated insertions and removals, 30 degree inclination recorded the highest retentive forces, followed by 10 degree, then 0 degree and 20 degree recorded the lowest retention values. Locator transparent recorded the highest retentive forces, followed by Locator pink, and Locator blue recorded the lowest retention values.
Conclusions:Comparing groups, the 30o group recorded the highest initial retention and 10o recorded the lowest for all types of locator inserts. The final retention values was not affected by 10 o mesial implant angulation, decreased with 20o and increased with 30o for locator blue and pink inserts. Comparing nylon inserts, the Locator transparent recoded the highest initial and final retention and initial stability followed by locator pink and locator blue recorded the lowest values for all groups.