Porcelain conditioning with Nd:YAG and Er:YAG laser for bracket bonding in orthodontics

In this study, shear bond strength (SBS) of metal orthodontic brackets to porcelain following conditioning by Er:YAG (erbium-doped yttrium aluminum garnet) and Nd:YAG (neodymium-doped yttrium aluminum garnet) laser in comparison to conventional methods was evaluated. One hundred glazed porcelain discs with an upper central shape were prepared and randomly assigned to five equal groups of 20. In the first group, samples were only deglazed and roughened by diamond burs. In the second group, after roughening and deglazing of porcelain samples, the samples were etched by 9.6% hydrofluoric acid for 4 min. Groups, 3, 4, and 5 were prepared by 0.8-W Nd:YAG laser, 2-W Er:YAG laser, 3-W Er:YAG laser for 10 s, respectively. Then, metal, mesh-based brackets were bonded to porcelain samples, and after being stored in distilled water for 24 h, debonding was carried out by a Zwick testing machine. ANOVA and Tukey tests were used to compare SBS in five groups. Mean SBS in groups 1 to 5 were 3.3 ± 1.6, 7.0 ± 2.1, 6.9 ± 2.7, 2.3 ± 1.1, and 3.7 ± 2.3 MPa, respectively. ANOVA test revealed a significant difference between five groups (p < 0.05). Although Tukey's test showed SBS in groups 2 and 3 were significantly higher than the other groups, they did not differ with each other significantly (p > 0.05). The results revealed that SBS of 9.6% hydroflouric acid and Nd:YAG Laser was in an acceptable range for orthodontic treatment. Nd:YAG laser was shown to be an acceptable substitute for hydrofluoric acid while Er:YAG laser with the mentioned power and duration was not a suitable option.