Fracture resistance of endodontically treated premolars restored with bulk-fill composite resins: The effect of fiber reinforcement.

Background: Coronal restoration of endodontically treated teeth (ETT) with mesio-occluso-distal (MOD) cavities is of a great importance in long-term success of the treatment. This study evaluated the effect of fiber reinforcement on the fracture resistance (FR) of ETT restored with flowable or paste bulk (PB)-fill composite resin compared to conventional composite (CC) resin.

Materials And Methods: In this experimental study, eighty maxillary premolars were divided into eight groups ( = 10). The first group was left intact (G) and the other groups received MOD cavities along with endodontic treatment. G: Remained unrestored while the other experimental groups were restored with three types of composite resin with or without fiber insertion. G: CC resin, G: PB fill, G: Flowable bulk fill (FB). G: Fiber + CC, G: Fiber + PB, and G: Fiber + FB. FR was tested at crosshead speed of 1 mm/min and recorded in Newton. Data were analyzed using one-way analysis of variance and Tukey's tests at significance level of < 0.05.

Results: G and G2 revealed the highest and the lowest FR, respectively. The mean FR of the testing groups in Newton was as follows: G = 1204.8 , G = 352.1 , G = 579.6 , G = 596.7 , G = 624.9 , G = 858.3 , G = 529.6 , and G = 802.5. Different uppercase letters indicate the significant difference between the groups.

Conclusion: The effect of fiber insertion on FR depended on the type of composite resin; the highest reinforcing effect was obtained in the CC resin + fiber, followed by bulk-fill flowable + fiber, and flowable bulk (FB)-fill composite resin. The strength of the former was significantly higher than the conventional and PB fill with and without fiber.