Fracture resistance of endodontically treated premolars restored with different restorations

Purpose: To compare in vitro fracture resistance of endodontically treated premolars restored with bonded amalgam or resin composite. Materials and Methods: Fifty intact and caries-free premolars that had been extracted for orthodontic treatment were selected. All teeth were subjected to endodontic procedures and MOD cavity preparation. They were then randomly divided into the five following groups of ten teeth each: without restoration (control group), intracoronal bonded resin composite restoration, intracoronal bonded amalgam restoration, cuspal coverage bonded resin composite restoration, and cuspal coverage bonded amalgam restoration. The teeth were embedded in poly(vinyl chloride) (PVC) blocks and subjected to compressive fracture tests. The fracture resistance was statistically analyzed using ANOVA and multiple comparison; Dunnett T3 test was performed at the 5% level. Results: The cuspal coverage bonded amalgam group provided significantly highest fracture resistance (1138.94 N). The fracture resistance of intracoronal bonded amalgam restoration (279.68 N) was less than the group of intracoronal resin composite (383.37 N) and not significantly different from that of the cuspal coverage bonded resin composite restoration (346.19 N) and the control group (257.90 N). Conclusion: Cuspal-coverage bonded amalgam restoration provided higher fracture resistance than cuspal-coverage bonded resin composite restoration while intracoronal bonded amalgam restoration provided lower fracture resistance than intracoronal bonded resin composite restoration. (Int Chin J Dent 2005; 5: 75-79.)