Effect of Nd:YAG irradiation and fluoride application on dentine resistance to erosion in vitro.
OBJECTIVE
In this paper we evaluated the effect of two fluoridated agents and Nd:YAG irradiation separately and in combination on dentine resistance to erosion.


BACKGROUND
The morphological changes in dentin induced by laser treatment may reduce the progression of erosive lesions. Due to the possibility of a synergistic effect of laser with fluoride, this study was conducted.


METHODS
Eighty bovine dentine samples (4 x 4 mm) were randomly divided into eight groups, according to the following treatments: G1: untreated (control); G2: acidic phosphate fluoride gel (APF 1.23%) for 4 min; G3: fluoride varnish (NaF 2.26%) for 6 h; G4: 0.5 W Nd:YAG laser (250 microsec pulse, 10 Hz, 35 J/cm2, 30 sec); G5: 0.75 W Nd:YAG laser (52.5 J/cm2); G6: 1.0 W Nd:YAG laser (70 J/cm2); G7: APF + 0.75 W Nd:YAG laser; and G8: NaF + 0.75 W Nd:YAG laser. After the treatments, half of each dentine surface was protected with nail varnish. The samples were stored in artificial saliva (30 mL/sample) for 24 h and submitted to four erosive 1-min cycles. Between the erosive attacks, the blocks were maintained in artificial saliva for 59 min. The erosive wear was evaluated by profilometry.


RESULTS
The mean wear (+/-SD, microm) was: G1: 1.20 +/- 0.20; G2: 0.47 +/- 0.06; G3: 0.81 +/- 0.11; G4: 1.47 +/- 0.32; G5: 1.52 +/- 0.24; G6: 1.49 +/- 0.30; G7: 0.49 +/- 0.11; and G8: 1.06 +/- 0.31 (Tukey's test, p< 0.05).


CONCLUSIONS
Laser irradiation was not able to reduce dentine erosion. However, fluoride application was able to increase the dentine's resistance to erosion, and APF showed better results than fluoride varnish.
Magalhães
Ana Carolina
AC
Department of Child and Social Dentistry, School of Dentistry of Araçatuba, São Paulo State University, Araçatuba, Brazil.
Rios
Daniela
D
Machado
Maria Aparecida De Andrade
MA
Da Silva
Salete Moura Bonifácio
SM
Lizarelli
Rosane De Fátima Zanirato
Rde F
Bagnato
Vanderlei Salvador
VS
Buzalaf
Marília Afonso Rabelo
MA
D000149:Acidulated Phosphate Fluoride / Q000008:administration & dosage*; D000818:Animals; D002417:Cattle; D003804:Dentin / Q000187:drug effects* / Q000528:radiation effects*; D005460:Fluorides, Topical / Q000008:administration & dosage*; D053844:Lasers, Solid-State; D014077:Tooth Erosion / Q000517:prevention & control*
D005460:Fluorides, Topical; D000149:Acidulated Phosphate Fluoride