الفهرس 
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Abstract
Purpose: The aim of this in vitro study was to evaluate the effect of different degrees of distal implant inclination on retention and stability of two-implant retained mandibular overdenture with locator attachments. Materials and Methods : Four duplicated clear acrylic experimental models were constructed. The models were covered by resilient silicone to simulate the oral mucosa. In the canine regions of each model, two recesses were prepared with following degrees of implant inclination : group I (0 o,control), group II ( 5 o), group III(10 o), and group IV (20 o). Four acrylic, metal reinforced overdenture was fabricated and connected to the implants using Locator attachments. Utilizing the Universal Testing Machine, vertical and 3 types of rotational (anterior, lateral and posterior) dislodgements were performed on a metal plate attached to the model with metal chains until the attachments separated from the abutments. The initial retentive force (maximum dislodging force) and final retention after 540 cycles of insertions and removals were measured for each example. Results: For initial retentive forces and retentive forces after repeated insertions and removals, 5 degree inclination recorded the highest retentive forces, followed by 10degrees, then 0 degrees and 20 degrees recorded the lowest retention values. Transparent insert recorded the highest retentive forces, followed by pink insert, green insert, blue insert and red insert recorded the lowest retention values. Conclusion: Comparing nylon inserts, transparent inserts showed the highest retention and stability with parallel and a slight degree of distal implant inclination after wear simulation, while with a high degree of inclination, blue and pink inserts showed the highest retention after wear simulation.