Comparison of fracture resistance between immediate and delayed composite restorations with or without fiber after root canal treatment: a field-emission-gun scanning electron microscope study

Abstract

Background This study aimed to evaluate the fracture resistance of immediate and delayed restorations after root canal treatment (RCT). Methods Sixty human intact premolar teeth were used. Teeth were prepared disto-occlusally. After RCT, teeth were randomly divided into two groups according to restoration times (immediate or 3 months delayed). The three month delay was imitated by thermomechanical aging. Then, samples were divided into six subgroups (n = 10). While I (Composite resin), II (Flowable bulk-fill) and III (Ribbond+Flowable bulk-fill) were restored immediately, Groups IV, V and VI were restored with temporary filling material and stored in distilled. After subjected to thermo-cycling (2,500 cycles, 5–55 °C) and exposed to 60,000 cycles in a chewing simulator, Group IV (Composite resin), V (Flowable bulk-fill) and VI (Ribbond+Flowable bulk-fill) were restored. All of the teeth were fractured on the universal testing machine. Failure modes were analyzed using scanning electron microscope. Data were analyzed using the Shapiro-Wilk and two-way ANOVA tests (p 0.05). Most of the repairable fractures were seen in Groups I and II. Conclusion Delaying the permanent restorations of teeth for 3 months did not affect fracture resistance. However, it was suggested to avoid delaying restorations for obtaining repairable surfaces.

Keywords

• Composite
• Delayed restorations
• Root canal treatment
• Polyethylene fiber
• Fe-sem