In vitro evaluation of enamel demineralization after Er:YAG and Nd:YAG laser irradiation on primary teeth

Objective: This in vitro study evaluated the influence of both Er: YAG and Nd: YAG laser irradiation on deciduous enamel demineralization. Background Data: Although there are still few studies on the use of the high-intensity laser for caries prevention in deciduous teeth, it is believed that its use on the dental structure can lead to a more acid-resistant surface. Methods: Forty enamel samples obtained from 22 deciduous first molar teeth were ground and randomly divided into four groups (n = 10): group 1 (G1), no treatment ( negative control); G2, fluoride ( positive control); G3, Er: YAG laser ( 2 Hz, 60 mJ, 40.3 J/cm(2)); G4, Nd: YAG laser ( 80 mJ, 10 Hz, 0.8 W). After the surface treatment, the samples were submitted to an acid challenge that consisted of a 5-day immersion in demineralizing ( 3 h) and remineralizing solution ( 21 h). Next, a microhardness test was preformed. Results: Analysis of variance ( ANOVA) and Student Newman Keuls tests were performed ( alpha = 5%). The percentage of lesion inhibition for each group was as follows: G2, 59.4%; G3, 35.7%; and G4, 40.4%. As regards the percentage loss of mineral volume, there was no statistical difference between groups G2 (444.37 +/- 146.42) and G3 (441.81 +/- 207.08) when compared with group G1 (281.03 +/- 134.57). All experimental groups presented a lower mineral loss compared with the non-irradiated samples ( G4). Conclusion: The findings of the present study revealed that both Nd: YAG and Er: YAG lasers can be an alternative tool for enhancing deciduous enamel acid resistance.