title: In vitro evaluation of enamel demineralization after Er:YAG and Nd:YAG laser irradiation on primary teeth.
abstract: OBJECTIVE
  This in vitro study evaluated the influence of both Er:YAG and Nd:YAG laser irradiation on deciduous enamel demineralization.
  
  
  BACKGROUND
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Special Laboratory of Lasers in Dentistry, University of São Paulo (USP), São Paulo, Brazil.
authors.forename: Carina S
authors.initials: CS
authors.lastname: Castellan
authors.forename: Ana Claudia
authors.initials: AC
authors.lastname: Luiz
authors.forename: Leticia M
authors.initials: LM
authors.lastname: Bezinelli
authors.forename: Roberta M G
authors.initials: RM
authors.lastname: Lopes
authors.forename: Fausto M
authors.initials: FM
authors.lastname: Mendes
authors.forename: Carlos
authors.initials: C
authors.lastname: De P Eduardo
authors.forename: Patricia M
authors.initials: PM
authors.lastname: De Freitas
mesh_terms: D003733:Dental Caries Susceptibility / Q000528:radiation effects; D003743:Dental Enamel / Q000528:radiation effects*; D006801:Humans; D007834:Lasers; D008963:Molar; D017001:Tooth Demineralization / Q000517:prevention & control*; D014094:Tooth, Deciduous / Q000528:radiation effects*