Effect of Different Restoration Designs on Fracture Strength of Endodontically Treated Teeth Weakened with MOD Cavities
Author(s): Alaa H Abbas* and Zainab M Abdulameer
Abstract
Purpose: The aim of this in vitro study was to evaluate the effect of different restoration designs on fracture strength and failure mode of endodontically treated upper first premolar with mesio-occluso-distal (MOD) cavity. Material and methods: Forty sound maxillary first premolars were divided into 5 groups (n=8): GA (intact group), GB-E (test groups). In tested groups, all the teeth were received MOD cavities and endodontically treated. GB: Endodontically treated teeth (ETT) restored with direct composite resins (Filtek™ Bulk Fill Posterior Restorative, 3M ESPE). While teeth in groups (C, D and E) were prepared to receive indirect ceramic restorations made from lithium disilicate material (IPS E-max CAD, Ivoclar-Vivadent). GC: ETT restored with overlays. GD: ETT restored with conventional crowns. GE: ETT restored with endocrowns. The indirect restorations were made by CAD/CAM system and adhesively cemented with dual-cure resin cement (RelyX™ Ultimate, 3M ESPE). Samples were mounted in a universal testing machine (LARYEE Universal testing machine, China). At a crosshead speed of 0.5 mm/min, each sample was loaded to failure. Failure modes were also observed. At P0.05, one-way analysis of variance (ANOVA) and Tukey's post hoc significance difference tests were used to analyze the data. Results: The results of this in vitro study revealed that the highest mean of fracture strength was recorded by GD (2013.750 N) followed by GC (1350 N), GE (1079.350 N), GA (1058.125 N) and GB (872.750 N) respectively. Tukey’s post-hoc test showed significant (p<0.05) differences among the different groups. Conclusions: Conventional crowns had the highest fracture strength, while direct composite had the lowest fracture strength. The most favourable combination of strength and failure mode could be observed in groups conventional crowns and overlays so that this restorations can be considered a clinically reliable restorative approach for ETT with MOD cavities.