Effect of Nd:YAG and CO2Laser Irradiation on Prevention of Enamel Demineralization in Orthodontics: In Vitro Study.
OBJECTIVE
The aim of this study was to investigate Nd:YAG and CO2laser effects in the prevention of demineralization in deeper layers of enamel via successive acid challenge cycles.


BACKGROUND
Lasers are promising in the prevention of enamel demineralization around the orthodontic brackets; however, there are very few studies that evaluate if the effects of treatment could be extended after successive acid challenge cycles due to permanent enamel structural alterations.


METHODS
Human enamel samples were divided into five groups (n = 12): G1-application of 1.23% acidulated fluoride phosphate gel (AFP, control); G2-Nd:YAG laser irradiation (0.6 W, 84.9 J/cm2, 10 Hz, 110 μs, contact mode); G3-Nd:YAG laser irradiation associated with AFP; G4-CO2laser irradiation (0.5 W, 28.6 J/cm2, 50 Hz, 5 μs, and 10 mm focal distance); and G5-CO2laser irradiation associated with AFP. The samples were submitted to successive acid challenge cycles. Quantitative light-induced fluorescence and scanning electron microscopy were used to assess enamel demineralization. The data were statistically compared (α = 5%).


RESULTS
G1: 50.87 ± 4.57; G2: 47.72 ± 2.87; G3: 50.96 ± 4.01; G4: 28.21 ± 2.19; and G5: 30.13 ± 6.38. The CO2laser groups had significantly lower mineral losses than those observed in all other groups after successive acid challenge cycles.


CONCLUSIONS
Only the CO2laser (10.6 μm) irradiation prevents enamel demineralization around the orthodontic brackets even after exposure to successive acid challenges. The CO2laser at 10.6 μm showed a deeper effect in enamel regarding caries prevention.
1 Master Program in Biodentistry, Ibirapuera University , São Paulo, Brazil .
Renato Siva
RS
Paulos
1 Master Program in Biodentistry, Ibirapuera University , São Paulo, Brazil .
Priscila Yumi
PY
Seino
1 Master Program in Biodentistry, Ibirapuera University , São Paulo, Brazil .
Karen Akemi
KA
Fukushima
2 Department of Restorative Dentistry, School of Dentistry, University of São Paulo , São Paulo, Brazil .
Marcia Martins
MM
Marques
3 Department of Community Dentistry, School of Dentistry, University of São Paulo, São Paulo, Brazil .
Fernanda Campos Sousa
FCS
de Almeida
1 Master Program in Biodentistry, Ibirapuera University , São Paulo, Brazil .
Karen Muller
KM
Ramalho
2 Department of Restorative Dentistry, School of Dentistry, University of São Paulo , São Paulo, Brazil .
Patricia Moreira
PM
de Freitas
4 Department of Biomedicine Engineering, Camilo Castelo Branco University , São Paulo, Brazil .
Aldo
A
Brugnera
1 Master Program in Biodentistry, Ibirapuera University , São Paulo, Brazil .|2 Department of Restorative Dentistry, School of Dentistry, University of São Paulo , São Paulo, Brazil .|5 Universidade Nove de Julho , São Paulo, Brazil .
Maria Stella
MS
Moreira
D003743:Dental Enamel / Q000528:radiation effects* / Q000648:ultrastructure; D006801:Humans; D066298:In Vitro Techniques; D054020:Lasers, Gas; D053844:Lasers, Solid-State; D028022:Low-Level Light Therapy / Q000379:methods*; D008855:Microscopy, Electron, Scanning; D009970:Orthodontics; D012680:Sensitivity and Specificity; D017001:Tooth Demineralization / Q000517:prevention & control*
CO2 laser; Nd:YAG laser; enamel demineralization; orthodontics; white spot lesion