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Fracture Resistance of Endodontically Treated Teeth Restored with Lithium Disilicate Crowns Retained with Fiber Posts Compared to Lithium Disilicate and Cerasmart Endocrowns: In Vitro Study

Saleh Al-shibri and Jylan Elguindy

Purpose: The purpose of this in vitro study was to compare the effect of endocrowns and glass fiber postretained crowns on the fracture resistance of endodontically treated maxillary premolars made of different ceramics materials.
Materials and Methods: Thirty sound maxillary premolars were endodontically treated. They were randomly assigned into 3 groups (n=10), in which, teeth were prepared to receive all- ceramic restorations. GP: fiber post and resin core and ferrule with all-ceramic (IPS E-max CAD, Ivoclar-Vivadent) conventional crown. GE: Endocrown with butt joint finish line design made of (IPS E-max CAD, Ivoclar-Vivadent). GC: Endocrown with butt joint finish line design made of hybrid nanoceramic (CERASMART, GC Dental, USA). The lithium disilicate (IPS E-max press, Ivoclar-Vivadent) and hybrid nanoceramic (CERASMART, GC Dental, USA) all-ceramic restorations were made by CAD/CAM system (CEREC MC XL SW 4.0) and adhesively cemented with dual-cure resin cement (BisCem Bisco, Inc, USA). Specimens were mounted in a universal testing machine (Model 3345; Instron Industrial Products, Norwood, MA, USA). Each specimen was loaded to failure at a crosshead speed of 5.0 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 (GC) recorded statistically significant (p<0.05) highest mean value (1522.64 N) followed by group (GP) (1301.34 N) then group (GE) (725.73 N). Group (GE) recorded the lowest statistically significant (p<0.05) mean value (725.73±137.89 N). Pair-wise Tukey’s post-hoc test showed nonsignificant (P>0.05) difference between GP and GC groups.
Conclusions: Within the limitations of this study, all fracture resistance loads obtained in this study were far beyond the maximum masticatory forces and the presence of hybrid nanoceramic increased the fracture resistance of endodontically treated maxillary premolars restored with endocrown than those restored with lithium disilicate endocrowns, in failure mode hybrid nanoceramic showed favorable fracture pattern than lithium disilicate.