Retention

ABSTRACT This study compares the wear changes and retention between two stud attachments “Ball” and “Novaloc” used for implanted supported mandibular overdenture. Two epoxy resin models represented completely edentulous patients were duplicated from an educational cast and prepared to receive two implant analogues in the canine area. Two different attachment systems were used: the first one was Ball attachment with a metal housing of gold insert, the second one was Novaloc with a PEEK matrix & insert. They were divided randomly into two groups. Two overdentures were fabricated for each group. The pick-up proceeded as conventional methods. Robota simulator applied multiple cycles mimicking the insertion and removal of the overdentures at the baseline, 500 cycles, 1000 cycles, 1500 cycles and 2000 cycles. Digital microscope evaluated the wear behavior of each attachment during these different cycles. Attachments retention was measured using universal testing machine. Wear changes comparison of both groups revealed that Novaloc group was significantly higher than Ball group between baseline and 2000 cycles. Regarding retention, comparison between both groups revealed that retention Novaloc group was significantly lower (P<0.05) than Ball group at baseline, 1000 cycles, 1500 cycles & 2000 cycles. The rate of wear was higher in Novaloc attachment which had PEEK Inserts than those of ball attachments with its gold precious alloy inserts. Regarding retention of both attachments, the Ball attachments had a significant higher initial and final retention values than the Novaloc attachments. Keywords: Novaloc attachment, Ball attachment, Retention, Wear changes

ABSTRACT This study aims to compare the retention and wear changes between two stud attachments “Locator” and “Novaloc” used for implant supported mandibular overdenture. Two ready-made epoxy resin models represented completely edentulous patients were prepared to receive two implant analogues in the canine area and divided randomly into two groups. The first group represented the Locator attachment with its nylon matrix and metal housing; the second one was Novaloc with its PEEK matrix. Two overdentures were constructed for each group. The pick-up proceeded as conventional method. Universal testing machine was used to measure the retention of each attachment. Chewing simulator exerted multiple cycles mimicking the insertion and removal of the overdentures at the baseline, 500 cycles, 1000 cycles, 1500 cycles and 2000 cycles. Digital microscope was used to evaluate the wear behavior of each attachment during these different cyclic loading. Regarding retention was performed by using Independent t-test which revealed that retention of group I (Locator) was significantly higher (P<0.05) than group II (Novaloc) at baseline, 500 cycles, 1000 cycles, 1500 cycles and 2000 cycles. Comparison between mean difference of wear (wear changes) of both groups was performed by using Independent t-test which revealed in the overall changes group I (Locator) was significantly higher than group II (Novaloc). The Locator showed higher initial retention than Novaloc. Regarding wear behavior, Novaloc showed lesser wear and changes than Locator attachment. Keywords: Locator attachment, Novaloc attachment, Retention, Wear.

ABSTRACT To investigate and compare the changes in retentive forces and wear resistance of two attachment systems Nova-loc& telescope with different design and overlaying patrices over two un splinted implant supported mandibular over denture under short-term simulated function. Two models carrying a two-implant analogue with two different types of overlying patrices Telescope and Nova loc over which an acrylic complete denture was constructed with picked up corresponding matrices. The tensile forces were applied using a universal testing machine to evaluate retention force, and digital microscope was utilities to evaluate wear resistance. Evaluation of retentive force & wear resistance of telescopic and Nova-loc IODs was carried out at five-time intervals; at baseline and after they are subjected to cyclic loading under at 500, 1000, 1500 and 2000 cycles of repeated insertion and removal. Retentive values were recorded by using independent t-test which revealed the retention of the group I (Telescope) was significantly higher (p<0.05) than those of group II (Nova loc) at baseline & after exposure to different cyclic loading (500- 1000- 1500- 2000). Regarding the wear, comparison of wear (wear change) of both groups was performed by using t-test between mean difference which revealed that the group I (telescope) was significantly higher than group II (Nova-loc). Regarding to Telescope and Nova-loc systems have satisfactory retentive forces, However, short-term successful clinical use in implant overdentures. Nova loc attachments are promising to be successfully used in implant overdentures as the Telescopic coping attachments with satisfactory retention. However, the retention value of Telescope higher than Nova loc, the wear behavior of Nova-loc lesser than Telescope due to the peek material. Keywords: Retention, Wear, Implant, Overdenture, Telescopic attachment, Novaloc attachment