Abstract
The aim of the study was to assess the effects of different surface conditioning protocols on shear bond strength (SBS) and on surface roughness (Ra) of ceramic porcelain surface. Also, the effect of refinishing of the conditioned surface was evaluated. For the same purpose, a total of 120 glazed ceramic porcelain veneer were prepared and randomly assigned into 4 groups of 30 specimens, according to the surface conditioning method applied: hydrofluoric acid etching (HF); deglazing using diamond bur (DB); sand blasting (SB) with 25 mu m aluminum trioxide (Al2O3); tribochemical silica coating (TS) with 30 mu m silica coated aluminum trioxide (Al2O3). Orthodontic brackets were bonded on all the specimens. 15 specimens from each groups were subjected to thermo-cycling and remaining 15 specimens served as the baseline (n = 15). Shear bond strength (SBS) was recorded using a universal testing machine. Surface roughness (Ra) was evaluated at baseline (Ra), following surface conditioning (Ra-1) and after polishing (Ra-2) with a non-contact profilometer. The data was analyzed by One-way ANOVA, Tukey's post hoc and Kruskalwallis test. Group TS exhibited highest SBS at baseline (14.68 +/- 0.28) and after thermo-cycling (12.67 +/- 0.22) while HF specimens exhibited lowest SBS at baseline (6.32 +/- 0.15) and after thermo-cycling (4.32 +/- 0.26). The surface roughness (Ra-1) was significantly affected by the surface conditioning in all the groups (P < 0.05). Group TB specimens demonstrated highest Ra-1 (1.21 +/- 0.53) and the lowest Ra1 (0.29 +/- 0.16) was observed in HF specimens. The polishing of the specimens significantly affected the roughness (Ra-2) values of the specimens. HF specimens demonstrated lowest surface roughness and lowest SBS; and TS specimens showed the highest surface roughness and highest SBS. Increased surface roughness enhanced SBS of the specimens. Polishing following debonding significantly decreased the surface roughness of the specimens.