Fracture Resistance of Endodontically Treated Teeth Restored with Bonded Post/Cores

Objectives: The purpose of this in vitro study was to investigate the fracture resistance and mode of failure of severely compromised endodontically treated teeth restored with three different adhesively bonded post/core systems.

Methods:  Post spaces were prepared in 30 mounted extracted endodontically treated maxillary anterior teeth. The teeth were randomly divided into three groups of 10 with the following treatments: PPXP: gold cast post/core (Parapost XP-lab); PPXH: Titanium prefabricated post/composite resin core (Parapost XH); DTLP: quartz fiber reinforced post/composite resin core (DT-Light post). All posts were cemented with Panavia 21 after applying ED primer on the canal dentin. Air-particle abrasion with Alloy Primer was applied on the metallic posts. All cores resembled a central incisor preparation with no remaining tooth structure above the preparation margin. Complete cast gold crowns were fabricated for all groups and cemented with Panavia 21. The specimens were subjected to thermal cycling (6,000 cycles) and cyclic loading (50,000 cycles) and failure was induced using a universal testing machine (Instron) at 0.5cm/min. Mode of failure was characterized by the interface separation (crown fracture, crown debonding, post fracture, post debonding, root fracture). Data were analyzed using 1-way ANOVA followed by post-hoc tests (α=.05).

Results:  The mean failure load (p=.002) for groups PPXP, PPXH and DDLP was 174.01N, 123.48N and 117.59N respectively, with group PPXP significantly different than group PPXH (p=.008) or DTLP (p=.003). The primary mode of failure for groups PPXP and PPXH was root fracture, and for group DTLP, post debonding.

Conclusions:  Endodontically treated teeth that exhibit severely compromised tooth structure, restored with bonded gold cast post/core showed significantly increased fracture resistance compared to teeth restored with bonded titanium posts or quartz fiber prefabricated posts and composite cores.