RESUMO
Endodontically treated teeth are generally weaker than sound teeth. The study objective was to compare the fracture resistance of endodontically treated teeth restored with different restorative techniques. Fifty extracted human maxillary central incisors of similar size were divided into five groups of 10 teeth. Group 1 was left intact as the control group. Other groups (Groups 2, 3, 4 and 5) were all endodontically treated followed by restorations using different restorative techniques; light cured composite resin (CR), CR and crown, post and CR, and post-CR core and crown respectively. The specimens were loaded in a universal testing machine with a static force at a crosshead speed of 0.5mm/min at 135° to the long axis of the root until failure. The means and the standard deviations of the maximum load at failure for groups 1, 2, 3, 4 and 5 were 1259.11N (379.12N), 578.63N (196.70N), 667.13N (298.72N), 1247.65N (294.48N) and 623.60N (193.75N) respectively. The results of one-way ANOVA showed statistically significant differences existed among the groups tested (p<0.001). Independent t-tests showed that the fracture resistance of specimens restored with either light cured composite resin or crown was statistically lower than the natural tooth (p=0.001 and p=0.003). Restoring endodontically treated with post significantly increased its fracture resistance to the level of sound tooth (p=0.002). Within the limitations of this study, endodontically treated teeth restored with post exhibited similar strength with sound natural teeth and restoration with either light cured composite resin or crown had lower fracture resistance than natural teeth.