CO2 Laser Effects on Shear Bond Strength of Orthodontic Brackets and Enamel Demineralization

Aim: of this in vitro study was to evaluate the effects of Co2 laser irradiation on demineralization adjacent to orthodontic brackets and their shear bond strength in human premolar teeth. Enamel demineralization adjacent to orthodontic brackets is a major problem that requires new professional method independent to patient cooperation.
Sixty human premolars were randomly divided to two groups (n=30). Group1, enamel surface irradiated with Co2 laser. Group2 without any enamel surface treatment. In both groups, a bracket at buccal surface was bonded with Transbond XT and cured with conventional light cure. Demineralization in all sample induced with artificial caries solutions. A universal testing machine was used to determine shear bond strengths. The teeth were sectioned bucco-lingually and were evaluated under polarized light microscope. Average lesion depths were calculated from three depth measurements. The Two independent sample T- tests were used to compare the study type group in detail.
The mean of shear bond strengths in the group1 and 2 were 13.90±5.01and 15.84 ±3.68 Mpa respectively, but not statistically significant (P=0.102).The mean lesion depth in group1and 2 was 72.29±58.09 µm 120.01±76.49µm respectively, which was significant (P=0.018)
Co2 laser irradiation can reduce enamel demineralization while not affecting the shear bond strengths significantly.