Material Thickness Influence on Fracture Load of Polymer Infiltrated Ceramic Network CAD/CAM Restorations

Abstract

Polymer infiltrated ceramics are hybrid materials that combine the strength of ceramics and the flexibility of polymers. The aim of this study was to compare the fracture load capacity of monolithic CAD/CAM crowns with different occlusal thicknesses, made from polymer infiltrated ceramic network. Fifteen full contour CAD/CAM crowns made of Vita Enamic with occlusal thicknesses of 0.5 mm, 1.0 mm and 1.5 mm were fabricated with a wet milling machine. Restorations were cemented on human molars with adhesive cement. Samples were loaded along the long axis until fracture, with a single static compressive force. A scanning electron microscope (SEM) was used to examine the fracture surface of specimens after the fracture. The results of this study reveals that the fracture load of the samples increased progressively with the occlusal thickness. The highest fracture value was recorded for1.5 mm occlusal thickness of the crown. No statistically significant difference was reported between the three experimental groups. It can be concluded that hybrid monolithic CAD-CAM crowns showed sufficient fracture strength to be used for single restorations in the posterior area, even with a reduced occlusal thickness.