Fracture resistance of endodontically treated maxillary premolars restored by silorane-based composite with or without fiber or nano-ionomer

Abstract

PURPOSEThis in vitro study investigated the fracture resistance of endodontically treated premolars restored using silorane- or methacrylate-based composite along with or without fiber or nano-ionomer base.MATERIALS AND METHODSNinety-six intact maxillary premolars were randomly divided into eight groups (n = 12). G1 (negative control) was the intact teeth. In Groups 2-8, root canal treatment with mesio-occlusodistal preparation was performed. G2 (positive control) was kept unrestored. The other groups were restored using composite resin as follows: G3, methacrylate-based composite (Z250); G4, methacrylate composite (Z250) with polyethylene fiber; G5 and G6, silorane-based composite (Filtek P90) without and with the fiber, respectively; G7 and G8, methacrylate- and silorane-based composite with nano-ionomer base, respectively. After aging period and thermocycling for 1000 cycles, fracture strength was tested and fracture patterns were inspected. The results were analyzed using ANOVA and Tukey HSD tests (α=0.05).RESULTSMean fracture resistance for the eight groups (in Newton) were G1: 1200 ± 169a, G2: 360 ± 93b, G3: 632 ± 196c, G4: 692 ± 195c, G5: 917 ± 159d, G6: 1013 ± 125ad, G7: 959 ± 148d, G8: 947 ± 105d (different superscript letters revealed significant difference among groups). Most of the fractures in all the groups were restorable, except Group 3.CONCLUSIONSilorane-based composite revealed significantly higher strength of the restored premolars compared to that of methacrylate one. Fiber insertion demonstrated no additional effect on the strength of both composite restorations; however, it increased the prevalence of restorable fracture of methacrylate-based composite restored teeth. Using nano-ionomer base under methacrylate-based composite had a positive effect on fracture resistance and pattern. Only fiber-reinforced silorane composite restoration resulted in a strength similar to that of the intact teeth.

Effect of Different Liners on Fracture Resistance of Premolars Restored with Conventional and Short Fiber‐Reinforced Composite Resins

“…One experienced operator made all preparations. Measurements were made with a digital caliper (Mitutoyo Digimatic; Mitutoyo, Kawasaki, Japan) with 0.1‐mm sensitivity for proper and accurate standardization of cavity dimensions …”

“…Measurements were made with a digital caliper (Mitutoyo Digimatic; Mitutoyo, Kawasaki, Japan) with 0.1-mm sensitivity for proper and accurate standardization of cavity dimensions. 30 The teeth were numbered from 1 to 120 and then randomly distributed into ten experimental groups of 12 teeth each using random numbers generated by a computer program. ANOVA analysis of average size (BL and MD) values of teeth in the ten groups showed no significant differences between the groups (p > 0.05).…”

Direct Restoration of Endodontically Treated Teeth: a Brief Summary of Materials and Techniques

“…[65,66] evaluated fiber-reinforced composite resin restorations and concluded that using polyethylene fiber under composite restorations in root-filled teeth with MOD preparations significantly increases fracture strength, reduces leakage in class 2 cavities [67], and strengthens microtensile bonding to dentin [68]. Furthermore, fiber reinforcement between the restorative resin and dentin changes the fracture line, causes repairable fractures, saving the remaining tooth structure [65,66,68], and increases the restorability of methacrylate-based composite resin-restored teeth after failure [69]. Although fiber-reinforced composite restorations are prone to aging due to exposure to the oral environment and the mechanical properties may deteriorate over time [70], one of the great benefits of this technology is the possibility of extending functional survival by repairing restorations in the oral cavity [71].…”

“…Compressive loading during the fracture resistance test may be distributed throughout the restored tooth by different materials. Thus, Shafiei et al (2014) [80] suggested covering the cusps with an amalgam and composite resin combination and found no difference between the group receiving direct composite coverage and the one undergoing amalgam-based composite restoration. Nevertheless, direct cusp coverage with composite restoration appears to be a reliable method in extensive cavities [44,73].…”

“…These hybrid systems contain both silorane-and oxirane-based monomers and have two main advantages: low polymerization shrinkage and increased hydrophobicity [53,81]. Although Lien and Vandewalle (2010) [82] found the microhardness and compressive strength of the material to be low, silorane-based composites significantly increase the fracture strength of endodontically treated premolars [69] and decrease total cusp displacement in MOD cavities [81]. The addition of fiber had no effect on the strength of the restoration, whereas the use of a nano-ionomer core under the silorane-based restoration showed an advantage in terms of fracture strength [69].…”