Effect of fiber post and cusp coverage on fracture resistance of endodontically treated maxillary premolars directly restored with composite resin.

INTRODUCTION: There are different reinforcement methods in restoring root-filled teeth. The aim of this in vitro study was to evaluate the effect of fiber post and cusp coverage on fracture resistance of endodontically treated maxillary premolars directly restored with composite resin.

METHODS: Seventy-five maxillary premolars were divided into 5 groups (n = 15). Except for the control group (intact teeth), in other groups mesio-occlusodistal (MOD) cavities were prepared after endodontic treatment. In the groups with cusp coverage, both buccal and lingual cusps were reduced up to 2 mm. Then specimens in the experimental groups were prepared as follows: composite resin restoration without post and cusp capping, composite resin restoration without post but with cusp capping, composite resin restoration with post but without cusp capping, and composite resin restoration with post and cusp capping. After finishing and polishing, the specimens were stored in distilled water at 37 degrees C for a week. Subsequent to thermocycling and exertion of compressive forces parallel to the long axes of the teeth at a strain rate of 2 mm/min, data were analyzed by using one-way analysis of variance and chi(2) test.

RESULTS: There were no significant differences in fracture resistance between the groups (P = .057). However, chi(2) test showed statistically significant differences between the groups in failure mode (P < .001). The highest number of favorable fractures was observed in the control group (intact teeth).

CONCLUSIONS: Root-filled maxillary premolars, restored with direct resin composite with or without fiber post and cusp capping, had similar fracture resistance under static loading.