Comparing different porcelain surface polishing techniques after orthodontic brackets debonding

Objectives: The present study was designed to investigate different polishing techniques used to restore feldspathic porcelain surface regarding surface roughness after debonding of orthodontic brackets. Methods: Metal discs of 1 cm diameter and 1 mm thickness (n=85) were prepared from Wiron 99 non-precious alloy (BEGO Bremer Goldschägerei with Herbst GmbH& Co. Bremen. Germany). The discs were veneered from one side by 1 mm thickness Vita VMK Master feldspathic porcelain (Vita zhan fabric H. Rauter GmbH & Co. KG. Germany). Five of these intact samples composed the control group (C). Orthodontic metal brackets were bonded at the center of each of the remaining discs (3M, Unitek),
and then discs were water stored for 30 days before rebounding. Brackets were debonded using bracket removing pliers, and resin was removed with a sharp chisel. The prepared specimens (n=80) were divided into 4 groups (n=20) according to the surface treatment they were to receive: (G1): using (Shofu, USA) porcelain veneer jkit, (G2): using (Ultradent, USA) porcelain finishing kit, (G3): using (Sof-lex 3M, USA) porcelain polishing kit, and (G4): no surface treatment. The surface roughness (Ra) was evaluated quantitatively using USB Digital microscope with a built-in camera (Scope Capture Digital Microscope, Guangdong, China). WSxM software was used to calculate root mean square (RMS) of the average height of every specimen expressed in (μm) in each group including control samples. Data was analyzed with 2-way ANOVA followed by student’s t test (p<0.05). Results: The polishing techniques affected surface roughness significantly (P<0.001), with significant higher Ra values than the glazed baseline porcelain. The surface roughness values were not statistically different among the polishing groups (P>0.05). Conclusion: The results of this study indicated that the tested polishing techniques improved the surface roughness greatly, however, were not able to reestablish the original glazed porcelain smoothness.