Effect of Endocrowns and Glass Fiber Post-retained Crowns on the Fracture Resistance of Endodontically Treated Premolars

Purpose: The purpose of this in vitro study was to compare the effect of endocrowns and glass fiber post-retained crowns on the fracture resistance of endodontically treated premolars prepared with or without ferrule. Materials and Methods: Twenty sound mandibular premolars were endodontically treated. They were randomly assigned into 4 groups (n=5), in which, teeth were prepared to receive allceramic restorations. Group 1: Endocrown without ferrule. Group 2: Endocrown with (1 mm wide shoulders and 2 mm axial wall heights) ferrule. Group 3: Glass fiber post and resin core and conventional crown without ferrule. Group 4: Glass fiber post and resin core and conventional crown with ferrule. The lithium disilicate all-ceramic restorations (IPS E-max press, Ivoclar-Vivadent) were made by injection technique and adhesively cemented (Variolink N, Ivoclar Vivadent). Specimens were mounted in a universal testing machine (Model LRX-plus; Lloyd Instrument Ltd., Fareham, UK). Each specimen was loaded to failure at a crosshead speed of 1.0 mm / min. Mode of failure was also examined. Data were analyzed using one way analysis of variance (ANOVA) and Tukey’s post hoc significance difference tests. Differences were considered significant at P<0.05. Results: One way ANOVA test showed that group (4) recorded statistically significant (p <0.05) highest mean value (1262.71±277.8 N) followed by group (2) (1139.7±227.94 N) then group (1) (725.73±137.89 N). Group (3) recorded the lowest statistically significant (p <0.05) mean value (588.17±94.11 N). Pair-wise Tukey’s post-hoc test showed non-significant (P>0.05) difference between 2 and 4 groups. Conclusions: Within the limitations of this study, the presence of ferrule increased the fracture resistance of endodontically treated premolars restored with either endocrown or glass fiber postand core and all-ceramic crown than those without ferrule. (3204) Mohamed Abdel-Aziz and Amal Abdallah A. Abo-Elmagd E.D.J. Vol. 61, No. 3