Effect of X-ray radiation dose on the bond strength of different adhesive systems to dentin.
OBJECTIVE
To investigate the influence of different x-ray radiation doses on the bond strength of adhesive restorations to dentin using different bonding strategies.


METHODS
Flat dentin surfaces on human molars were obtained and cylinder-shaped specimens for the microshear bond test were built up with a composite (Z250, 3M ESPE), using three adhesive systems: a two-step etch-and-rinse (Single Bond 2--SB2, 3M ESPE), a two-step self-etching (Clearfil SE Bond--CSE, Kuraray), or a single-step self-etching (Adper Prompt--ADP, 3M ESPE). The specimens were assigned to 4 groups (n = 10), according to the x-ray dose: 0 (control), 5, 35, or 70 Gy. Radiation was directed to the surface of the resin cylinders. Microshear testing was conducted after 24 h, and the failure modes classified under magnification (200X). Data were submitted to two-way ANOVA and Holm-Sidak's test (p < or = 0.05). A nonlinear regression analysis was carried out with bond strength as dependent variable.


RESULTS
Bond strength results were dose and material dependent. SB2: control > 5 = 35 > 70; CSE: control = 5 > 35 = 70; ADP: control = 5 = 35 = 70. Generally, SB2 > CSE > ADP. The nonlinear regression plots showed that in general, an increase in radiation dose may predict a decrease in bond strength (R2 > or = 0.905). Failure modes were dependent on the bonding system, generally with no significant influence of radiation.


CONCLUSIONS
X-ray radiation might present a dose-dependent detrimental effect on the bond strength of resin composite restorations to dentin.
Biscaro
Sandro L
SL
Department of Oral Diagnosis, Oral Radiology Division, Piracicaba Dental School, State University of Campinas, Avenida Limeira 901, Piracicaba, Brazil.
Moraes
Rafael R
RR
Correr
Américo B
AB
Almeida
Solange M
SM
Bóscolo
Frab N
FN
Soares
Carlos J
CJ
Correr-Sobrinho
Lourenco
L
D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry / Q000528:radiation effects; D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects; D001840:Dental Bonding; D003804:Dentin / Q000528:radiation effects* / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008422:Materials Testing; D011829:Radiation Dosage; D019279:Resin Cements / Q000737:chemistry / Q000528:radiation effects; D033081:Shear Strength; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry; D014965:X-Rays
C438313:Clearfil SE Bond; D003188:Composite Resins; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; C408584:Prompt L-Pop; D019279:Resin Cements; C115612:single bond; D014867:Water; D017438:Bisphenol A-Glycidyl Methacrylate