Comparison of different doses of Er:YAG laser irradiation combined with MI-varnish on the inhibition of enamel demineralization

Purpose White spot lesions during fixed orthodontic treatment can be prevented by the application of lasers, fluoride varnishes or products containing calcium-phosphorus. This novel study aimed to evaluate the effect of different doses of Er:YAG laser irradiation combined with casein phosphopeptide-amorphous calcium phosphate varnish (MI varnish 5% NaF with 2% CPP-ACP) on the prevention of enamel demineralization around orthodontic brackets. Methods Buccal surface of eighty extracted human permanent premolars was prepared. Specimens were randomly divided into 8 groups (i.e., 10 per each): A: Er:YAG laser with 0.9 mm tip B: Group A + varnish C: Er:YAG laser with 7 mm tip D: Group C +varnish E: Er:YAG laser with 1.3 mm tip F: Group E+ varnish G: MI varnish H: control. Er:YAG laser was irradiated at energy densities as 10 J/cm 2 , 620 J/cm 2 or 300 J/cm 2 . The teeth were further subjected to 10-day pH cycling (6-h demineralization /18-h remineralization). The excrement of calcium and phosphorous ions was quantified by inductively coupled plasma (ICP). Results The laser treatments with 1.3, 0.9, and 7 mm diameter and the interaction of laser and MI varnish have no significant preventive effect against enamel demineralization, but MI varnish application ( p value = 0/005) reduced enamel white spots. Conclusions There was a tendency to higher caries resistance by MI varnish application However, Er:YAG laser irradiation did not have a remarkable effect on demineralization control. Clinical Relevance MI varnish can control caries, whereas Er:YAG laser irradiation does not have a protective effect.