Ayaka Shirasaki, DDS, Satoshi Omori, DDS, PhD, Chiharu Shin, DDS, PhD, Mina Takita, DDS, Reina Nemoto, DDS, PhD, and Hiroyuki Miura, DDS, PhD
Department of Fixed Prosthodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
Purpose: To evaluate the influence of occlusal and axial tooth reduction on the fracture load of polyetheretherketone (PEEK) molar restorations after mechanical cycling (MC).
Materials and Methods: Occlusal and axial tooth reductions were defined to two-types with each, four-types of abutment tooth were prepared. Minimal occlusal reductions were 1.0-mm and 1.5-mm, and finishing lines were chamfer and deep-chamfer (1.0/C, 1.0/DC, 1.5/C, 1.5/DC). Four groups of PEEK restorations were duplicated. The thicknesses of restorations were same as each reduction. After cementation, one-half of the specimens were subjected to mechanical cycling (group MC); the others were stored without additional stress (group MC0). All specimens were loaded vertically until fracture. The maximum fracture loads were recorded and fracture modes were observed. Fracture loads were analyzed using Dunn’s test with Bonferroni correction (α = 0.05).
Results: There were no significant differences among specimens prepared the same way in groups MC0 and MC. In group MC, the fracture load of specimens with 1.0-mm occlusal reduction were significantly higher than that of 1.5-mm. The fracture loads of PEEK restorations in all preparations were higher than maximum occlusal forces and were not decreased after mechanical cycling.
Conclusion: The fracture loads of PEEK restorations in all preparations were higher than maximum occlusal forces and were not decreased after MC. Based on these results, PEEK restorations with less preparation can withstand long-term use in the oral environment.
(Asian Pac J Dent 2018; 18: 29-36.)
Key Words: fracture load, mechanical cycling, molar, polyetheretherketone, restoration, tooth preparation