Comparative Evaluation of the Fracture Resistance of Fractured Teeth Reattached Using Different Preparation and Restoration Techniques: An In Vitro Study

Introduction: The restoration of fractured anterior teeth remains a clinical challenge because an ideal technique should preserve tooth structure while providing adequate mechanical strength and esthetic outcomes. Although fragment reattachment is a conservative approach, various preparation designs have been proposed to improve fracture resistance, and evidence comparing their performance remains limited. Our aim was to evaluate and compare the fracture resistance of Ellis Class II fractured maxillary central incisors restored using bevel preparation, single groove preparation, double-groove preparation, and direct composite build-up techniques. Methodology: This in vitro experimental study included 40 extracted permanent maxillary central incisors, which were randomly allocated into four groups (n = 10 each). Standardized Ellis Class II fractures were created, followed by restoration using bevel reattachment, single groove reattachment, double-groove reattachment, or direct composite build-up. All specimens were restored using a universal adhesive system and microhybrid composite resin. After finishing and polishing, fracture resistance was evaluated using a universal testing machine at a crosshead speed of 1 mm/minute. Data were analyzed using one-way analysis of variance, followed by Tukey's post hoc test, with statistical significance set at P < 0.05. Results: Fracture resistance differed significantly among the four groups (P < 0.001). The direct composite build-up group demonstrated the highest mean fracture resistance (239.23 ± 56.61 N), followed by the double-groove (198.60 ± 28.40 N), single-groove (169.94 ± 43.52 N), and bevel (134.53 ± 28.85 N) groups. Pairwise analysis showed that the fracture resistance of the direct composite build-up was significantly higher than that of the bevel and single groove techniques, whereas the double-groove technique exhibited significantly greater fracture resistance than the bevel preparation. Conclusions: Direct composite build-up exhibited the highest fracture resistance among the evaluated restorative techniques. Among the fragment reattachment methods, double-groove preparation provided superior reinforcement and may represent the preferred conservative technique when a fractured fragment is available.