Endocrowns for Rehabilitation of Anterior Teeth: In Vitro Mechanical Analysis

Objective This article evaluates the fracture load after mechanical cycling of severely damaged endodontically treated teeth restored with: (1) fiber post, composite resin core, and lithium disilicate (LD) crown; (2) individually fabricated LD post-core and LD crown; (3) LD endocrown; or (4) resin matrix ceramic endocrown. Materials and Methods Sixty bovine roots were endodontically treated and prepared for intraradicular retention at depths of 10 or 5 mm. Fiber posts or individually fabricated LD post-cores were cemented into 10-mm-deep prepared root canals. LD crowns were manufactured and cemented onto the cores. Endocrowns (LD or resin matrix ceramic) were fabricated and cemented into 5-mm-deep prepared roots. All samples (n = 15) were subjected to mechanical cycling (1 × 10 ⁶ cycles at 100 N and 4 Hz), followed by fracture load testing and failure mode analysis. Statistical Analysis Data were subjected to Kruskal-Wallis followed by Dwass-Steel-Critchlow-Fligner test (α = 0.05). Results The LD post-core group exhibited seven failures regarding endodontic retention during mechanical cycling and showed the lowest fracture load (192.9 N; p = 0.021). The highest fracture load was observed in the resin matrix ceramic endocrown group (713.9 N), with three catastrophic failures (root fracture). The fiber post-resin core-crown group presented the lowest number of failures during fatigue test (13%) and the lowest number of catastrophic failures (13% root fracture). Discussion The improved bonding potential of resin matrix ceramic endocrowns may contribute to higher fracture resistance and enhanced survival under mechanical fatigue compared to LD post-core systems. Conclusion Resin matrix ceramic endocrowns are an option for restoring anterior severely damaged endodontically treated teeth, with the highest load to failure. However, the conventional post-core-crown strategy demonstrated lower number of failures during fatigue and lowest number of catastrophic failures (root fracture).