Evaluation of Mean Retentive Values in Three Different Milled Framework Material in Implant Supported Mandibular Overdentures: An In Vitro Study

Abstract

Statement of Problem:Implant overdentures are an excellent treatment option as they increase stability, retention, improve masticatory function.Various attachment systems used to improve the retention and stability of implant supported overdentures,The bar system plays great role especially with 4 implants design.However the super structure sleeve material is still a point to be chosen carefully. Material&Methods:The aim of this study was to evaluate mean retentive value in three different milled framework attachments(Zirconia Z,titanium T and Peek P frameworks)in implant supported mandibular overdentures using universal testing machine.The study was conducted invitro using a mandibular acrylic model with 4implants inserted in the canine and second premolar regions.Over these implant titanium bar and 3superstructure(Z, T and P)frame works were constructed.The mean retention of each design was measured after periods of simulated use. Results:Two-way ANOAVA showed that significant differences in retention force(N) exist between groups and simulated periods of use(p<0.001). (N) after simulated cycles of insertion and removal to mimic different usage periods were:For P group, immediate at insertion(73.9±7.3)followed by insignificant decrease after 1year(70.3±3.4)followed by 2years(67.5±2. 5)and a significant decrease at 3years(65.0±7.0)compared to immediate at p=0.02.But for T group,3years(27.3±2.6)resulted in significant lowest (N) followed by 2years(33.6±4.2)followed by 1year(44.2±5.3)compared to immediate(56.4±6.2)at p<0.001.For Z group,1year (17.3±2.8) showed an insignificant decrease in(N)followed by 2years(15.3±3.1)and significant decrease at 3years(6.3±0.9)compared to immediate (30.0±4.8)at p<0.001. Conclusion combining of titanium bar with peek sleeve showed the best retention value,Titanium bar with the titanium sleeve showed satisfactory retention values but less and titanium bar with zircon sleeve showed the least retention values.