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Shear Bond Strength of Nanohybrid Composite to the Resin Matrix Ceramics After Different Surface Treatments.

OBJECTIVE
The purpose of this study was to evaluate the effects of different surface treatments on the shear bond strength (SBS) of a composite resin to the various resin matrix ceramics (RMC).


BACKGROUND
Clinical applications of physical and chemical surface conditioning methods may be required for RMC to optimize the adhesion of additional resin materials.


MATERIALS AND METHODS
Ninety-nine RMC specimens (6 × 6 × 2 mm) were prepared from a resin nanoceramic (RNC), a polymer-infiltrated hybrid ceramic (PIHC), and a flexible hybrid ceramic (FHC) block with a cutting machine under copious water. All specimens divided randomly into three surface treatment subgroups (n = 11): (1) untreated (Cnt), (2) tribochemical silica coated (Tbc), and (3) neodymium-doped yttrium aluminum garnet (Nd:YAG) laser irradiated with 3 W (150 mJ/pulse, 20 Hz) for 20 sec. A nanohybrid composite resin was layered with a disc-shape mold (2 × 3 mm) onto the ceramics and submitted to thermal cycling (3000 cycles, 5-55°C). The SBS test of specimens was performed using a universal testing machine. Data were statistically analyzed with two-way analysis of variance (ANOVA) and Tukey HSD test (α = 0.05).


RESULTS
The type of RMC, surface treatments, and their interactions was statistically significant on SBS, according to the ANOVA (p < 0.05). Both the Tbc and Lsr surface treatments significantly increased the SBS values of FHC (p < 0.001), while significant increases were observed only for Lsr0applied RNC and Tbc applied PIHC groups (p < 0.001).


CONCLUSIONS
The tribochemical silica coating and laser irradiation techniques may be suitable for improving the surface topography of specific types of RMC. While the same surface treatment technique may not provide similar successful results for all types of RMC, it is recommended to choose the most effective and reliable technique for clinical application.