Bond strength of dental adhesive systems irradiated with ionizing radiation.
OBJECTIVE
The aim of the present paper was to determine the effect of different types of ionizing radiation on the bond strength of three different dentin adhesive systems.


METHODS
One hundred twenty specimens of 60 human teeth (protocol number: 032/2007) sectioned mesiodistally were divided into 3 groups according to the adhesives systems used: SB (Adper Single Bond Plus), CB (Clearfil SE Bond) and AP (Adper Prompt Self-Etch). The adhesives were applied on dentin and photo-activated using LED (Lec 1000, MMoptics, 1000 mW/cm2). Customized elastomer molds (0.5 mm thickness) with three orifices of 1.2 mm diameter were placed onto the bonding areas and filled with composite resin (Filtek Z-250), which was photo-activated for 20 s. Each group was subdivided into 4 subgroups for application of the different types of ionizing radiation: ultraviolet radiation (UV), diagnostic x-ray radiation (DX), therapeutic x-ray radiation (TX) and without irradiation (control group, CG). Microshear tests were carried out (Instron, model 4411), and afterwards the modes of failure were evaluated by optical and scanning electron microscope and classified using 5 scores: adhesive failure, mixed failures with 3 significance levels, and cohesive failure. The results of the shear bond strength test were submitted to ANOVA with Tukey's test and Dunnett's test, and the data from the failure pattern evaluation were analyzed with the Mann Whitney test (p = 0.05).


RESULTS
No change in bond strength of CB and AP was observed after application of the different radiation types, only SB showed increase in bond strength after UV (p = 0.0267) irradiation. The UV also changed the failure patterns of SB (p = 0.0001).


CONCLUSIONS
The radio-induced changes did not cause degradation of the restorations, which means that they can be exposed to these types of ionizing radiation without weakening the bond strength.
Department of Oral Diagnosis, Dental School of Piracicaba, State University of Campinas, Piracicaba, SP, Brazil. cruz_a_d@fop.unicamp.br
Adriana
A
Dibo da Cruz
Luciano de Souza
Lde S
Goncalves
Alessandra Nara de Souza
AN
Rastelli
Lorenco
L
Correr-Sobrinho
Vanderlei Salvador
VS
Bagnato
Frab Norberto
FN
Boscolo
D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000528:radiation effects; D001840:Dental Bonding; D003799:Dental Stress Analysis; D017220:Dentin-Bonding Agents / Q000528:radiation effects*; D006801:Humans; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D010755:Organophosphates / Q000528:radiation effects; D019279:Resin Cements / Q000528:radiation effects*; D033081:Shear Strength; D018709:Statistics, Nonparametric; D014466:Ultraviolet Rays; D014965:X-Rays
C489661:Adper Prompt Self-Etch; C438313:Clearfil SE Bond; D017220:Dentin-Bonding Agents; D010755:Organophosphates; D019279:Resin Cements; C511238:Single Bond Plus; D017438:Bisphenol A-Glycidyl Methacrylate