Influence of surrounding wall thickness on the fatigue resistance of molars restored with ceramic inlay

Abstract

The purpose of this study was to evaluate the influence ofbuccal and lingual wall thickness on the fatigue resistance of molarsrestored with CAD/CAM ceramic inlays. Forty human third molarswere selected and divided into 4 groups, according to the remainingsurrounding wall thickness chosen for inlay preparation (n = 10): G1,2.0 mm; G2, 1.5 mm; G3, 1.0 mm; G4, 0.5 mm. All inlays were madefrom feldspathic ceramic blocks by a CAD/CAM system, and cementedadhesively. After 1 week stored in distilled water at 37 °C, the specimenswere subjected to fatigue testing under the following protocol:5Hz; pre-load of 200 N for 5,000 cycles, followed by increasing loads of400, 600, 800, 1000, 1200 and 1400 N for 30,000 cycles each. The specimenswere cycled until failure or completion of 185,000 cycles. The survivalrate of the groups was compared using the Kaplan-Meier survivalcurves (p > 0.05). All specimens withstood the fatigue protocol (185,000cycles), representing a 100% survival rate. The Kaplan-Meier survivalcurves showed no difference between groups. It can be concluded thatthe remaining tooth wall thickness did not influence the fatigue resistanceof molars restored with CAD/CAM ceramic inlays.