Influence of Nd:YAG laser irradiation on microtensile bond strength of adhesive systems to sound or carious dentin.
OBJECTIVE
To evaluate the microtensile bond strength of 2 adhesive systems (Adper Single Bond Plus [3M ESPE] and Clearfil SE Bond [Kuraray]) to carious or normal dentin, with or without previous treatment with Nd:YAG laser or Nd:YAG laser associated with fluoride.


METHODS
Dentin surfaces of 60 human third molars were exposed. Teeth were divided into 12 groups; groups 1 to 6 were submitted to pH cycling for artificial caries, and groups 7 to 12 remained with normal dentin. Dentin surfaces received 3 treatments: laser Nd:YAG irradiation (60 mJ, 15 Hz, and 0.9 W) for 1 minute; laser Nd:YAG irradiation associated with fluoride in gel; and no treatment (controls). In experimental groups, adhesive systems were applied in accordance with the manufacturers' instructions, and a composite resin block (Filtek Z250, 3M ESPE) was made incrementally for the microtensile bond strength test. The teeth were sectioned serially in both x and y directions, and sticks were submitted to microtensile bond strength testing in a universal testing machine.


RESULTS
According to ANOVA and Tukey (P < .05), the highest mean bond strengths were obtained in groups of normal dentin treated with Clearfil SE Bond (40.65 MPa) and Single Bond (34.2 MPa). The presence of carious dentin significantly decreased the mean bond strengths of the 2 adhesive systems whether or not they were previously laser irradiated. Nevertheless, Clearfil SE Bond presented the best microtensile bond strength on an irradiated surface. Moreover, laser irradiation associated with fluoride also decreased the bond strength values of the 2 adhesive systems.


CONCLUSIONS
After excavating a cavity with caries-affected dentin, the use of Nd:YAG laser followed by a self-etching adhesive system is the best clinical choice when considering bond strength, compared with the total etching- based system and laser.
Paranhos
Maria Paula Gandolfi
MP
School of Dentistry, Pontifical Catholic University of Rio Grande do Sul, Rio Grande do Sul, Brazil.
Spohr
Ana Maria
AM
Marcondes
Maurem
M
Oshima
Hugo Mitsuo Silva
HM
Mota
Eduardo Gonçalves
EG
Burnett
Luis Henrique
LH
D000134:Acid Etching, Dental; D017438:Bisphenol A-Glycidyl Methacrylate / Q000528:radiation effects; D002327:Cariostatic Agents / Q000627:therapeutic use; D003188:Composite Resins; D001840:Dental Bonding; D003731:Dental Caries / Q000628:therapy*; D003799:Dental Stress Analysis; D003804:Dentin / Q000528:radiation effects / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000528:radiation effects*; D005459:Fluorides / Q000627:therapeutic use; D006801:Humans; D053844:Lasers, Solid-State / Q000627:therapeutic use; D008855:Microscopy, Electron, Scanning; D008964:Molar, Third; D019279:Resin Cements / Q000528:radiation effects*; D013057:Spectrum Analysis / Q000379:methods; D013718:Tensile Strength
D002327:Cariostatic Agents; C438313:Clearfil SE Bond; D003188:Composite Resins; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; D019279:Resin Cements; C511238:Single Bond Plus; D017438:Bisphenol A-Glycidyl Methacrylate; D005459:Fluorides