Influence of the frequency of Er:YAG laser on the bond strength of dental enamel.
OBJECTIVE
The present study had the aim of evaluating the influence of different frequencies of the Er:YAG laser on adhesive resistance of enamel and one restorative system.


BACKGROUND
There have been no reports of studies assessing the influence of the pulse frequency variation of the Er:YAG laser on adhesive resistance of the enamel/resin interface.


METHODS
Fifty surfaces of enamel from extracted human third molars were planed and divided into five groups at random. Enamel surface treatment was realized by the Er:YAG laser at 80-mJ power and 1-, 2-, 3-, and 4-Hz pulse frequencies, followed by etching. For the control group, only acid conditioning with 37% phosphoric acid for 15 sec was used. The Single Bond/Filtek Z250 system was chosen for the fabrication of the specimens, which were stored in 100% relative humidity for 24 h, at 37 degrees C. The specimens were submitted to tensile resistance tests using a Universal Testing Machine (50 Kgf and 0.5 mm/min).


RESULTS
The mean values in MPa were 1 Hz, 25.58 (+/-6.16); 2 Hz, 25.58 (+/-3.79); 3 Hz, 21.34 (+/-3.78); 4 Hz, 21.17 (+/-3.13); and phosphoric acid only, 22.44 (+/-7.0). Data were submitted to statistical analysis using ANOVA, and there was no significant difference in tensile resistance between the studied groups.


CONCLUSIONS
The results suggest that the Er:YAG laser, with 80-mJ power associated with acid conditioning at 1-, 2-, 3-, and 4-Hz frequencies, did not present significant improvement in tensile bonding of enamel, as compared to acid conditioning only.
School of Dentistry of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
Mariane
M
Gonçalves
Silmara Aparecida Milori
SA
Corona
Jesus Djalma
JD
Pécora
Regina Guenka Palma
RG
Dibb
D000134:Acid Etching, Dental; D000704:Analysis of Variance; D001840:Dental Bonding; D003743:Dental Enamel / Q000187:drug effects / Q000528:radiation effects*; D006801:Humans; D007834:Lasers; D008964:Molar, Third; D010756:Phosphoric Acids; D013499:Surface Properties / Q000187:drug effects / Q000528:radiation effects
D010756:Phosphoric Acids; C030242:phosphoric acid