Direct Restorations Versus Full Crowns in Endodontically Treated Molar Teeth: A Three-Year Randomized Clinical Trial.

Abstract

Objectives: To compare the survival and success rates of direct composite resin restorations versus metal-ceramic crowns in endodontically treated molar teeth with minimal structure loss.

Methods: This clinical trial included 60 participants, each with an endodontically treated molar with at least three remaining axial walls (>2mm). Half of the participants received direct restorations, and half metal-ceramic crowns. USPHS criteria were used at baseline and annually for three years. Kaplan-Meier and log-rank tests analyzed survival/success rates. Cox regression evaluated predictors, and Mann-Whitney U and Wilcoxon tests compared USPHS outcomes.

Results: Fifty-three participants completed the 3-year follow-up (7 dropped out). The three-year survival rate for crowns was 93.3% (95% CI: 78.7%-98.2%), while the direct restoration group had 76.7% (95% CI: 59.1%-88.2%). The difference was insignificant (P=0.061). Success rates were also comparable (crowns=90.0% vs. restorations=76.7%; P=0.138). Bruxism significantly predicted failure (HR=12.8, 95% CI: 1.2-133.3, P=.032). Direct restorations had worse outcomes than crowns regarding caries (P=.018), surface texture (P=.019), and marginal integrity (P=.006). Crowns had worse outcomes in terms of periodontal indices (P=.032) and presence of periapical infection (P=.023). Over time, direct restorations significantly deteriorated in terms of caries (P=.041), margin discoloration (P=.007), margin integrity (P=.026), and fracture (P=.034), while crowns showed no significant changes.

Conclusion: For endodontically treated molars with minimal structure loss, both direct composite resin restorations and full crowns demonstrated similar survival and success after 3 years of function. However, crowns were more predictable, especially for bruxers. Direct restorations may suit cases with lower occlusal loads, endodontic monitoring, or budget constraints.