Effect of fiber reinforcement techniques on fracture resistance of endodontic treated premolars: In vitro Comparative Study

This in vitro comparative study aimed to evaluate the fracture resistance of various fiber-reinforced techniques for restoring endodontic treated premolars with extensive MOD cavity design. Fifty intact maxillary first premolars with two roots were randomly divided into five groups (n=10). Extensive MOD cavity preparation with the following dimensions  (5-6 mm depth of cavity with no proximal steps and with width 1/2 the intercuspal distance with endodontic treatment was done for all groups, except for group A (control group) (n=10) which remained sound without any preparation; after adhesive treatment and band application; teeth were restored with different fiber-reinforced materials with a final occlusal layer of hybrid composite as follows: Group-B: a wallpapering technique with ribbond fibers. Group-C: buccolingual application of ribbond with smart dentin replacement bulk increment. Group-D: Ever X posterior bulk-fill restoration. Group E: Bioblock technique with ever X flow composite. Fracture resistance and the mode of fracture were measured using compressive axial loading until fracture occur in a computer-controlled universal testing machine (LARYEE, Jinan, Shandong, China). The bio block technique yielded the highest fracture resistance among restored groups but with no statistically significant difference with wallpapering technique. Group C showed significantly lower fracture resistance values compared to intact teeth. Fiber-reinforcement techniques (polyethelene and glass fibers) both increase the fracture resistance of endodontically treated teeth but not to the level of intact teeth.