Introduction: Telescopic retainers would provide excellent retention due to the frictional fit between the primary and secondary coping. The aim of this invitro study was to compare the changes of retention between milled zirconia and PEEK framework for a telescopic implant retained overdenture after being subjected to 12500 and 37500 cycle.
Materials and methods: An epoxy resin model of a completely edentulous mandible received four implants installed in the intra-foraminal area. Four custom-made titanium abutments were the primary coping. The secondary coping was a framework that was made of milled zirconia (Group I) and milled polyetheretherketon (PEEK) (group II). Three frameworks in each group, were picked up in a metal prosthetic part. The metal prosthetic part was designed to measure retention using the universal testing machine at base line then subjected to chewing cycles of 12,500 cycles and 37,500 using the chewing simulator then retention was evaluated again.
Results In both groups there was a significant decrease in retention from base line and after being subjected to 12500 cycle and 37500 cycles. Group I recorded higher statistically significant retention values at base line, after 12500 cycle and after 37500 (8.473±2.368) (4.148±0.844) (p=0.024). Group I showed a greater change in retention from base line to 12500 cycle and from baseline to 37500 cycles which wasn't significant. Comparison between the groups was done using Paired t-test. P-value was insignificant > 0.05.
Conclusion : The milled zirconia framework used as a secondary coping showed higher retention values compared to the milled PEEK framework