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.
Department of Oral Diagnosis, Oral Radiology Division, Piracicaba Dental School, State University of Campinas, Avenida Limeira 901, Piracicaba, Brazil.
Sandro L
SL
Biscaro
Rafael R
RR
Moraes
Américo B
AB
Correr
Solange M
SM
Almeida
Frab N
FN
Bóscolo
Carlos J
CJ
Soares
Lourenco
L
Correr-Sobrinho
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