Effectiveness of surface polishing after debonding of metal brackets from different CAD-CAM materials.

Abstract

The purposes of this study were to compare and evaluate the surface texture of different restorative computer-aided design and computer-aided manufacturing (CAD/CAM) materials before bonding and after debonding of metal orthodontic brackets. Atotal of 60rectangular ceramic test specimens (n = 20 in each group) were prepared using feldspathic ceramic blocks (FLD; served as control), hybrid ceramic blocks (HC), and lithium disilicate ceramic blocks (LDC). Surface roughness (Ra) analysis was conducted using aprofilometer before bonding the metal brackets. After the debonding and polishing procedures, asecond surface roughness analysis was conducted on each specimen. The shear bond strength (SBS) test was applied to each specimen using auniversal test machine for debonding the metal brackets. The debonded specimens were examined under astereomicroscope and scored using a4-step adhesive remnant index (ARI). The Ra and SBS values and the ARI scores were saved, and the data were analyzed statistically at asignificance level of 0.05. One specimen from each group was examined under atomic force microscopy to visualize surface roughness. Furthermore, one specimen from each group was additionally prepared for scanning electron microscopy analysis. Statistically significant differences in SBS measurements were observed between all three groups. The highest SBS values were obtained from the FLD group, the lowest from the LDC group. The HC group showed significantly (P = 0.001) lower Ra values than the LDC and FLD groups after debonding and polishing. No significant differences were observed in the ARI scores between the groups. Hybrid ceramics could be asuitable alternative for fixed restorations in adult patients receiving subsequent treatments with fixed orthodontic appliances.