Effect of femtosecond laser on the bond-strength of bracket porcelain

Method: In total, eighty glazed feldspathic porcelain samples were prepared and randomly assigned to four groups (n=20): Group SB, 50 µm Al2O3 sandblasting; Group HF, 9.6% hydrofluoric acid gel; Group NY, Nd:YAG laser; Group FS, femtosecond laser treatment. The surfaces were treated with a silane agent. Brackets were bonded to porcelain samples and after stored in distilled water for 24 h and then thermocycled for 500 cycles between 5 and 55°C. The shear bond strengths (SBSs) of the brackets were performed with a universal testing machine at a crosshead speed of 1 mm/min until bonding failure occurred. The data were analyzed statistically using ANOVA and Tamhane multiple comparisons tests.

Result: The mean ± SD (MPa) SBS values were Group SB, 9.07±3.76, Group HF, 9.09±3.51, Group NY, 5.11±1.53, and Group FS, 11.58±4.16. ANOVA indicated that the SBS values varied according to the surface treatment method (p < 0.05). Results of the Tamhane post hoc tests indicated that the bond strength in Group NY was significantly lower than the other groups (p < 0.05).

Conclusion: Femtosecond laser treatment can be used as an alternative method for bonding brackets to feldspathic porcelain.