Fracture resistance and fracture modes in endodontically treated maxillary premolars restored using different CAD-CAM onlays.

Purpose: To examine the fracture resistance and fracture modes of endodontically treated teeth (ETT) restored using onlays of different materials fabricated using computer-aided design and computer-aided manufacturing (CAD-CAM).

Methods: Sixty maxillary first premolars were randomly assigned to six groups (n=10). The first group comprised intact teeth (INT).