Effect of thermocycling on acetal resin versus PEEK surface hardness and flexure strength of implant-retained overdenture bars: in vitro study

Abstract Background Implant-supported mandibular overdentures with bar attachments are considered an excellent option for a completely edentulous mandible. It provides a long-lasting and reliable solution to restore function and aesthetics to the patient. Many materials can be used for the construction of bar attachments, among which are PEEK and Acetal resin materials. The choice between PEEK and Acetal bar attachments eventually depends on the application, considering factors such as load-bearing requirements, biocompatibility, adaptability, and ease of use. Methods Twelve 3D-printed edentulous mandible models each received two implants. Models were then divided into two equal groups. Group1: Six models with PEEK bars were fabricated by thermo-pressed technique while Group 2: Six models with Acetal resin bars were fabricated by thermo-pressed technique. Surface hardness and flexure strength were then evaluated and statistically analyzed before and after thermocycling. Results PEEK group revealed significant higher surface hardness than Acetal resin before and after thermocycling. Regarding flexure strength, PEEK showed an insignificant increase than Acetal before thermocycling; however, the PEEK group displayed much higher values than the Acetal group following the thermocycling, resulting in a significant difference between the two groups. Conclusions Bar made of PEEK showed more promising surface hardness and flexure strength than Acetal resin bar.