Fracture Toughness Comparison of Three Indirect Composite Resins Using 4-Point Flexural Strength Method

Abstract

Objectives The advantages of indirect composite restorations such as less crack formation during their computer-aided design/computer-aided manufacturing process, compared with ceramic restorations, have resulted in their growing popularity. However, restoration failure is a major concern with regard to the long-term clinical success of restorations and may occur as the result of propagation of a crack originated from an internal flaw in the restoration. This study aimed to compare the fracture toughness of three indirect composite resins. Materials and Methods In this in vitro experimental study, 10 specimens measuring 3 × 3 × 18 mm were fabricated of Gradia, Crios, and high impact polymer composite indirect composites. A single edge notch with a diameter < 0.3 mm and 0.3 mm length was created in the 9 mm longitudinal dimension of specimens using a no. 11 surgical scalpel. The specimens were then subjected to 4-point flexural strength test in a universal testing machine with a crosshead speed of 0.1 mm/s until failure. Statistical Analysis Data were analyzed using IBM SPSS Statistics via one-way analysis of variance (ANOVA) and Tukey’s HSD (honestly significant difference) test. The statistical power was set at p ˂ 0.05. Results One-way ANOVA showed a significant difference in fracture toughness of the three composite groups (p = 0.000). According to the Tukey HSD analysis, the fracture toughness of HIPC was significantly higher than that of the other two composites. The fracture toughness of Gradia was significantly lower among all. Conclusions Within the limitations of this study, the results showed that high temperature-pressure polymerization can increase resistance to crack propagation and subsequently improve the clinical service of indirect composite restorations. Although we do not know the filler volume percentage of HIPC, it seems that filler volume percentage of the composite is inversely correlated with fracture toughness.

Acid Resistance of CAD/CAM Resin Composites

“…Due to their lower brittleness compared to ceramics, these materials can be designed with lower minimum layer thicknesses and thinner margins, which requires less invasive preparation of the abutment teeth [ 14 ]. In addition, less chipping and intraoral reparability are advantageous properties of CAD/CAM resin composites [ 15 , 16 ]. Furthermore, in comparison to ceramics, CAD/CAM resin composites are beneficial in terms of their hardness, strength, and elastic moduli, which are comparable to tooth structure [ 17 , 18 ].…”

“…Furthermore, in comparison to ceramics, CAD/CAM resin composites are beneficial in terms of their hardness, strength, and elastic moduli, which are comparable to tooth structure [ 17 , 18 ]. This leads to less wear of antagonist enamel [ 13 , 15 , 17 ].…”

Comparative wear analysis of conventional versus CAD/CAM composite veneered PEEK crowns using 3D surface deviation

“…55,56 Micro-ceramic particles in HIPC might play a significant role in protecting its surface from wear during the friction force application and developing the HIPC's higher fracture toughness. 57 However, it is claimed that the existence of large particles as micro-ceramics could theoretically lead to further erosion of the restorative material in wear tests. 58 When the restoration is subjected to chewing forces, the stress extends through resin-filler particles to the resin matrix resulting in easy elimination of these particles from the surface, exposing the organic matrix, and accelerating wear.…”

Marginal microleakage and modified microtensile bond strength of Activa Bioactive, in comparison with conventional restorative materials

“…At present, the use of tooth‐colored restorative materials has dramatically increased due to the higher esthetic demands of patients (Moradi et al, 2020). However, despite the advances in the composition of composite resins and their optimal physical properties, their application is time‐consuming, and polymerization shrinkage is still a significant drawback (Brunthaler et al, 2003; Opdam et al, 2004; Radhika et al, 2010).…”