Abstract
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 × 106 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).
Keywords
crowns - ceramics - lithium disilicate - fatigue
