Comparison of fracture resistance and microleakage of direct and indirect restorations in endodontically treated molars with extensive coronal loss : Comparison of endocrown restorations made by different methods in endodontically treated teeth.

OBJECTIVES: This study aimed to compare the fracture resistance and microleakage of direct composite endocrowns, indirect composite endocrowns, and fiber-reinforced indirect composite endocrown restorations placed on endodontically treated mandibular molars with extensive coronal loss in vitro. MATERIALS AND METHODS: Seventy-eight mandibular molars were endodontically treated and randomly divided into three groups (n = 26): Group 1—direct composite endocrown restorations, Group 2—indirect composite endocrown restorations, and Group 3—fiber-reinforced indirect composite endocrown restorations. Following thermocycling, 13 specimens from each group were subjected to fracture resistance testing, while the remaining 13 specimens were evaluated for microleakage. Fracture loads were recorded in Newtons (N). Fracture patterns and microleakage scores were assessed. Data normality was verified using the Shapiro–Wilk test, and statistical analysis was performed using one-way ANOVA followed by post hoc tests (α = 0.05). RESULTS: No statistically significant differences were observed in fracture resistance among the groups (Group 1: 2459.2 ± 382.5 N; Group 2: 2453.7 ± 409.6 N; Group 3: 2257.3 ± 527.6 N; p > 0.05). However, indirect composite endocrown restorations (Group 2) demonstrated significantly more favorable fracture pattern scores compared with direct composite endocrowns (Group 1) (p < 0.05). Regarding microleakage, direct composite endocrowns exhibited significantly higher leakage scores than both indirect composite and fiber-reinforced indirect composite endocrown restorations (p < 0.05). CONCLUSIONS: Within the limitations of this in vitro study, all tested restoration types demonstrated fracture resistance values exceeding normal masticatory forces. Indirect and fiber-reinforced indirect endocrown restorations showed improved marginal sealing performance compared with direct composite endocrowns. CLINICAL RELEVANCE: Fiber-reinforced indirect composite endocrowns may represent a conservative and adhesive restorative option for endodontically treated molars with extensive coronal loss. The adhesive bonding approach allows stress distribution without the need for post placement, potentially preserving remaining tooth structure.