Comparison of Fracture Resistance of Endodontically Treated Human Mandibular Molars Restored with Paracore Dual-cure Composite and EverX Posterior Composite: An In-vitro Study

Abstract

Introduction: Endodontic treatment is an elective dental procedure that is performed when the dental pulp becomes irreversibly damaged or necrotic due to dental caries or trauma. Considerable loss of coronal tooth structure together with large cavity designs and access cavities compromise the mechanical behaviour of endodontically treated teeth, making them more susceptible to catastrophic fracture. Hence, following endodontic treatment, it is imperative to provide a suitable restorative material to avoid subsequent tooth fracture following occlusal loading. Aim: To assess and compare the fracture resistance of endodontically treated human mandibular first molars restored with dual-cure composite (Paracore) and newer short fibre-reinforced composite (EverX Posterior) in occlusal (Class-I) cavities. Materials and Methods: The in-vitro study was performed in January 2023 to February 2023 using 30 freshly extracted sound adult human mandibular first molars (divided in three groups) at Guru Nanak Institute of Dental Sciences and Research, Kolkata, West Bengal, India. A total of 10 intact teeth served as positive controls (Group-1). Class-I access cavity preparation followed by endodontic therapy was performed on the remaining 20 teeth, which were randomly divided into two groups (Group-2 and 3), which were coronally restored with Paracore dual-cure composite and EverX posterior composite, respectively. Teeth were mounted in acrylic resin, and subsequently, measurements of fracture strength were performed using a universal testing machine. Data were analysed statistically using One-way Analysis of Variance (ANOVA), Post-Hoc Tukey, and Chi-square tests, with a p-value of ≤0.05 considered as the level of significance. Results: The mean fracture resistance values (in kilonewtons) were as follows: Group-1 (1.5750 kN) > Group-3 (1.0450 kN) > Group-2 (0.6350 kN). Group-3 showed a significantly higher mean fracture resistance value (p=0.035) than the other experimental group. The levels of fractures were also evaluated, and a significant difference between the groups was noted (p=0.001), concluding that the frequencies of unfavourable fractures were significantly higher in Group-2 than in the other groups. Conclusion: Short fibre-reinforced composite (EverX) showed fracture resistance similar to that of a natural tooth and hence can be used as a direct core build-up material to reinforce the remaining tooth structure in endodontically treated teeth.

Keywords

• core build-up material
• endodontic therapy
• fibre-reinforced composite
• occlusal cavities