Repairability of Aged Dimethacrylate-Free ORMOCER-based Dental Composite Resins with Different Surface Roughening Methods and Intermediate Materials.

Statement of problem. The repair of damaged composite resin restorations has been recommended as a conservative treatment option. However, a reliable protocol for repairing ORMOCER-based restorations is lacking. Purpose. The purpose of this in vitro study was to investigate the effect of different surface roughening methods, repair composite resins, and intermediate materials on the repair bond strength of a dimethacrylate-free ORMOCER-based composite resin. Material and methods. Cylindrical composite resin specimens (Admira Fusion) were roughened by using hydro fluoric acid (HF) or a diamond rotary instrument. In both groups, 4 types of intermediate materials were used (Monobond-S, Clear fil SE bond [second bottle], Clear fil Universal bond, GC Composite Primer), and then half of the specimens were repaired with a similar composite resin, and the other half with dimethacrylate composite resin (Clear fil-APX). The specimens (n=20) were then subjected to repair bond strength and failure mode evaluation. The data were analyzed by using the Weibull test, 3-way and 1-way ANOVA, and the Tukey honestly significant difference (HSD) test ( a =.05). Results. All variables, including the surface roughening method, intermediate material, and repair composite resin, had a significant effect on repair bond strength ( P <.001). The lowest repair bond strength values were obtained in the group roughened with HF, prepared with Monobond-S, and repaired with Admira Fusion, and the highest values were obtained in the group roughened with a rotary instrument, prepared with GC Composite Primer, and repaired with Clear fil APX ( P <.05). All experimental groups had a lower bond strength than the cohesive and control groups ( P <.05). In all experimental groups, the predominant failure modes were adhesive and mixed. Conclusions. The use of a diamond rotary instrument was a more reliable method of creating roughness, and different intermediate materials based on the clinical situation can be used to repair dimethacrylate-free ORMOCER-based composite resin with similar or different composite resins. However, in general, the highest repair bond strengths were achieved with Clear fil APXrepaired specimens.