The Effect of Direct Veneers and Resin Posts on the Fracture Resistance of Endodontically Treated Teeth

This study evaluates the effect of restoring endodontically treated maxillary incisors with two brands of direct composite veneers, with or without fibre-reinforced resin posts, on fracture resistance. Forty-two maxillary central incisors extracted for periodontal reasons were selected, ensuring they were free of caries, cracks, or fractures. Following endodontic treatment, the teeth were divided into six groups (n = 7 per group): Group1 (Control group): Teeth restored with composite resin sealing the access cavity without additional preparation, Group 2: Prepared for direct composite veneers but left unrestored, Group 3: Restored with direct composite veneers using Tetric N-Ceram composite, Group 4: Restored with direct composite veneers using Tetric N-Ceram composite reinforced with fiber-reinforced resin posts, Group 5: Restored with direct composite veneers using Z250 3M composite, and Group 6: Restored with direct composite veneers using Z250 3M composite reinforced with fiber-reinforced resin posts. All teeth were subjected to a compression load test using a universal mechanical testing device at a 1 mm/min crosshead speed until fracture occurred. Fracture resistance values were analyzed using One-Way ANOVA and Bonferroni tests. The mean fracture resistance (N ± SD) was: Group 1 (control): 762.2 ± 15.96, Group 2: 660.5 ± 35.15, Group 3: 890.5 ± 26.23, Group 4: 1015.8 ± 43.19, Group 5: 889.4 ± 23.19, and Group 6: 1001.4 ± 18.23, Statistically significant differences (p < 0.05) were observed between the control group and all other groups, as well as between groups 2, 3, and 5 compared to groups 4 and 6. No significant differences were observed between groups 3 and 5 or between groups 4 and 6. Preparation for veneers reduced fracture resistance in endodontically treated maxillary incisors. Restoring with direct composite veneers significantly increased fracture resistance regardless of the composite material used. Fibre-reinforced resin posts further enhanced fracture resistance in prepared teeth restored with direct composite veneers, irrespective of the composite material brand.