Rana Osama El-Bahrawy, Zeinab Ahmed El-Shourbagy And Safaa Al-Sayed Asal,

ABSTRACT
Purpose Compare Retention And Wear Characteristics Of Locator And OT Equator Attachments Used In Two Implant Retained Mandibular Overdenture.

Materials and Methods: Fourteen Ready Mandibular Epoxy Resin Models Were Used. Two Implant Fixtures With 4 Mm Diameter And 11mm Length Were Installed In The Canine Area. Group (I) Received Locator Abutments With White Nylon Inserts While Group (II) Received OT Equator Attachments With Clear Nylon Inserts. The Final Constructed Mandibular Overdentures Were Subjected To 240,000 Cycle Of Bi-axial Chewing Simulating Cycles And 1080 Manual Insertion-removal Cycles. The Retention Of The Samples Were Measured Using Universal Testing Machine At The Beginning Of The Study And After 3,6,9,12 Months Of Functional Simulation. Wear Features In The Nylon Inserts Were Also Observed By USB Digital Microscope With Built In Camera At The Beginning Of The Study And At 3,6,9,12 Months. Results The Locator Attachments Showed 31.89% Loss Of Initial Retention After One Year Of Simulated Function Compared To 46.44% Loss Of OT Equator Retention. Notable Wear And Surface Alterations Were Visible Under Photomicrograph On Nylon Inserts Of Both Attachments. However, Both Systems Nevertheless Fulfilled The Minimum Retention Requirements Put Forward By Other Authors During Simulation Of One Year Functional Life. Conclusion Statistically Significant Differences In Retention Develop Between The Two Systems, With OT Equator Undergoing A Greater Loss Of Retention Than Locator.