Methods:
Sixty bovine enamel blocks were subjected to short-term acidic exposure by immersion in cola drink for 6 min, resulting in surface softening without tissue loss. Than 40 sound and 40 eroded enamel blocks were randomly and equally divided into 4 groups (n=10) according to treatment: C- untreated (control); CO- CO2 laser irradiation 28.6J/cm2; F- AmF (1% F) fluoride application; CO + F- CO2 laser irradiation and subsequent fluoride application. Laser irradiation was performed with at 10.6 µm wavelength, 5 µm pulse duration and 50 Hz frequency. During 5 days the erosive cycle was conducted by immersion of the blocks in cola drink for 2 min, followed by immersion in artificial saliva for 120 min. This procedure was consecutively repeated 4 times per day. The blocks were maintained in artificial saliva overnight. Enamel loss was measured profilometrically after initial group treatment and after 1 and 5 days of erosive challenge. The data were tested using two way ANOVA and Tukey’s test (p<0,05).
Results: After treatments no enamel loss was observed on the studied groups (< 0.1 µm). After one day of erosive cycling, only fluoride treatment, for sound enamel; and fluoride associated or not to laser irradiation, for eroded enamel; resulted in less enamel loss compared to control groups. On the fifth day only fluoride on sound enamel significantly differed from control, with a preventive effect.
Conclusions:
Based on the results, CO2 laser irradiation when associated to fluoride has a limited effect against erosion and fluoride still the most effective treatment for enamel prevention.