Repair Bond Strength in Hybrid Ceramic Preconditioned With Ho: YAG Laser and Toluidine Blue, Activated by Low-Level Laser Therapy, Using Composites With Varying Viscosities: An Analysis of Surface Topography and Elemental Analysis

The current study is designed to evaluate and contrast the effectiveness of several pretreatment techniques, such as airborne particle abrasion (APA), toluidine blue (TBO) activated by low-level laser therapy (LLLT), and the Ho: YAG (Holmium: yttrium aluminum garnet crystal) laser, along with composite repair materials of varying viscosities, on the surface roughness (Ra) and repair bond strength (RBS) of hybrid ceramics (HBC). Seventy-eight discs of HBC measuring 3 × 8 × 10 mm were obtained from Vita Enamic hybrid ceramics. The discs were then arbitrarily allocated into three groups based on the conditioning techniques that is, APA, Ho: YAG laser, and TBO activated by LLLT (n = 26). The Ra of five specimens from each group following conditioning were quantified utilizing a contact profilometer and one disc from each group was utilized for surface topography assessment under scanning electron microscopy (SEM). The remaining 20 discs from each group were further divided into two subgroups based on the type of composite resin (n = 10). Microhybrid composite (A) and a low viscosity injectable composite (B). Following bonding with different composite types all samples underwent thermocycling. RBS and failure mode analysis were performed with the universal testing machine and stereomicroscope respectively. The data concerning Ra and bond strength was subjected to ANOVA and Tukey Post Hoc test to identify significantly different outcomes among tested groups (p = 0.05). The maximum scores of mean Ra were displayed by Group 2 (Ho: YAG laser) (1234.33 ± 0.035 μm) pretreated discs. Whereas Group 3 (TBO activated by LLLT) (987.12 ± 0.012 μm) conditioned samples exhibited the lowest outcomes of Ra. The highest scores of RBS were presented by Group 2B (Ho: YAG laser + Injectable composite) (12.83 ± 0.22 MPa). Conversely, the lowest mean RBS value was recorded in Group 3A (TBO activated by LLLT + Microhybrid composite) (10.21 ± 0.24 MPa) Repairing CAD/CAM-HBC materials, using a Ho: YAG laser for surface conditioning proves to be the most effective approach. Regardless of the surface treatment chosen, using injectable composite as the repair material results in improved RBS.