REPAIR BOND STRENGTH, SURFACE ROUGHNESS, AND TOPOGRAPHIC ASSESSMENT OF NANOCOMPOSITE CERAMICS WHEN SURFACE MODIFIED WITH A NANOSECOND LASER; LOW-LEVEL LASER THERAPY ACTIVATED MALACHITE GREEN AND TRI-BIOCHEMICAL SILICA

The impact of different surface modifiers, i.e., tri-biochemical silica coating (TBC), low-level laser therapy (LLLT) using malachite green (MG) and a nanosecond (ns) laser on the surface roughness (Ra) and repair bond strength of a nanocomposite ceramic (NCC) to a composite was elucidated upon. NCC discs were manufactured by utilising prefabricated blocks and underwent disinfection. These discs were subsequently categorised into four groups at random, applying various surface modifiers (n=16) - Group 1: HFA ⁺ S; Group 2: TBC ⁺ S; Group 3: LLLT (MG) ⁺ S and Group 4: ns laser ⁺ S. A topographic evaluation following surface modification was performed using Scanning Electron Microscopy (SEM). An Ra analysis was performed on five specimens using a surface profilometer. A composite was applied to repair the ceramic surface, where the repair bond strength and failure mode assessment was performed utilising a universal testing machine and stereomicroscope, respectively. The data were analysed using a one-way analysis of variance (ANOVA), and Tukey's post-hoc test, with p˂0.05 deemed significant. The highest Ra values (1558.38 ± 0.022 μm) and repair bond strength (18.22 ± 0.19 MPa) of the NCC were observed in Group 2 (TBC) samples. However, the Group 3 LLLT-MG pre-treated samples exhibited the lowest roughness (1009.24 ± 0.021 μm) and bond strength (13.18 ± 0.32 MPa) values. A tribochemical silica coating and nanosecond laser can be used as an alternative conditioning regime for nanocomposite ceramics as they positively influence the repair bond strength and Ra.