To evaluate clinical effects of of computer aided design and computer aided manufacturing (CAD/CAM) on the ceramic onlay restoration of endodontically treated posterior tooth.

126 endodontically treated posterior teeth were restored with chair-side CAD/CAM ceramic onlays. The patient satisfaction surveys were carried out immediately after restoration. Clinical evaluations, including marginal adaptation, contour apearance, surface texture, color match were made according to the modified United States Public Health Service (USPHS) criteria immediately after the restoration and 1 year follow-up.

More than 91% patients were satisfied with the restorations. According to USPHS criteria, 92.1% and 91.3% (χ²= 0.052, P = 0.820) restorations reached A level inmarginal adaptation immediately and in 1 year follow-up, and that was 97.6% for the contour appearance, 95.2% and 93.7% (χ²=0.303, P = 0.582) for the surface texture, 80.2% and 81.7%(χ²= 0.103, P = 0.748) for the color match. Only one ceramic restoration fractured during follow-up.

CAD/CAM ceramic onlays have good clinical effect in restoration of endodontically treated posterior teeth.