[Fracture resistance of endodontically treated maxillary premolars restored with different CAD/CAM all-ceramic restorations].

PURPOSE: This study was to evaluate the fracture resistance of endodontically treated maxillary premolars restored with different CAD/CAM all-ceramic restorations in vitro. METHODS: Mesio-occluso-function tip(MOF) cavities were prepared in 21 extracted human maxillary premolars due to endodontic treatment. The teeth were divided into 3 groups. G1:conventional composite resin; G2: cavities；G3: conventional composite resin with a horizontal glass fiber post inserted palatal walls. Restorations were fabricated from a pressable lithium disilicate glass-ceramic and adhesively cemented (Rely X U200). Then, the specimens were subjected to a compressive load at a crosshead speed of 0.5 mm/min until fracture. The fractured specimens were analyzed to determine the fracture pattern using a stereomicroscope. SPSS 15.0 software package was used to analyse the data. RESULTS: G3（1570.7+/-108.7） had higher failure load than G1(1214.6+/-95.8) and G2(1285.9+/-87.6)(P<0.05). G1 was similar to G2.The crown was lost in G1 and G2. There was a fracture of the crown and tooth in G3. CONCLUSIONS: CAD/CAM all-ceramic crown with fiberglass posts might be an effective method for restoration of endodontically treated premolars with MOF cavity defect.