Direct restorations versus full crowns in endodontically treated molar teeth: A three-year randomized clinical trial

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.

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.

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 = 0.032). Direct restorations had worse outcomes than crowns regarding caries (P = 0.018), surface texture (P = 0.019), and marginal integrity (P = 0.006). Crowns had worse outcomes in terms of periodontal indices (P = 0.032) and presence of periapical infection (P = 0.023). Over time, direct restorations significantly deteriorated in terms of caries (P = 0.041), margin discoloration (P = 0.007), margin integrity (P = 0.026), and fracture (P = 0.034), while crowns showed no significant changes.

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.

This study showed similar 3-year survival/success rates of direct composite restorations compared to metal-ceramic crowns in restoring endodontically treated molar teeth with minimal structural loss. These results indicate that direct restorations may be suitable alternatives for molars with minimal structural loss, particularly in cases with reduced occlusal loads, a need for endodontic monitoring, or financial limitations.