Bond strength of composite-to-composite resin repair following aging protocol
MetadataShow full item record
Purpose: The purposes of this study are: (1) to evaluate the effect of aging procedure on the repair bond strength, (2) to determine the impact of using dissimilar composites on the bond strength of the repair after aging. Materials and Methods: Disc-shaped nanohybrid (Tetric EvoCeram-TE) resin composite specimens (N = 90) were photopolymerized and stored in distilled water at 37°C for 24 hrs. Specimens were randomly divided into two groups: non-aged (no thermocycling) and aged (thermocycling 5000 times, 5 to 55°C). Specimens were etched (35% phosphoric acid-Ultra-Etch, Ultradent) and intermediate adhesive was applied (OptiBond Solo Plus, Kerr). Three different resin composites, one of the same type as the substrate (nanohybrid) and the others of a different kind (microhybrid and microfilled) were adhered onto the conditioned substrates. Shear force was applied to the adhesive interface in a universal testing machine (cross-head speed: 1 mm/min) until fracture occurred.The mean peak force was measured in MPa. Results: A statistically significant difference in bond strength by the composite repair material was observed (p < 0.05), but the aging method did not have a significant effect on repair bond strength (p = 0.3). The interaction was not significant (p = 0.822). Microfilled repair group showed statistically significant lower mean bond strength (13.01 ± 4.4 MPa) than that of microhybrid repair group (19.04 ± 6.9 MPa). However, there was no statistically significant difference in mean bond strength between nanohybrid and microhybrid repair groups or between nanohybrid and microfilled repair groups. Conclusion: (1) Aging did not affect the repair quality. (2) Composite repair material did not have an effect on the repair bond strength. (3) Microfilled repair group showed lower bond strength when compared to microhybrid repair group. There was a significant difference in bond strength between the two dissimilar composite repair groups. However, there was no significant difference between either of the dissimilar composite repair groups and the same composite repair group. (4) Microfilled repair group failed adhesively while microhybrid repair group had mixed fracture mode.