Influence of radiation on bond strength.
OBJECTIVE
The aim of this in vitro study was to evaluate the shear bond strength of two adhesive systems--Prime & Bond NT (PBNT) and Clearfil SE Bond (CSEB)--to dentin irradiated before or after adhesive application.


METHODS
Thirty extracted molars were sectioned mesiodistally with a diamond bur. The inner surface of each tooth's dentin was ground flat with SiC abrasive papers. The roots of the sectioned teeth were mounted in a cylindrical mold using chemically cured acrylic resin. In groups A1 and B1, a radiation dose of 60 Gy (R) was applied to the dentin surfaces at this point. In all groups, adhesives were applied according to the respective manufacturer's instructions. Cylindrical composite resin restorations (CRR; internal diameter 3 mm, height 4 mm) were then placed on the center of the flattened dentin surfaces. At this point, groups A2 and B2 received 60 Gy of radiation, and groups C1 and C2 remained as nonirradiated controls. Thus, the test groups were: A1: R + PBNT (Primed Bond NT) + CRR; A2: PBNT + CRR + R; B1: R + CSEB (Clearfil SE Bond) + CRR; B2: CSEB + CRR + R; C1: PBNT+ CRR; C2: CSEB+ CRR. Specimens were mounted in a universal testing machine and shear load was applied at a crosshead speed of 1 mm/min until failure. Bond strength values were calculated as MPa and the results were evaluated statistically using repeated measures of two-way ANOVA, with significance set at p < 0.05.


RESULTS
Irradiation significantly affected adhesion of composite to dentin in groups A1 and A2 (p = 0.002). Group A1 showed statistically lower bond strength than group A2 (p < 0.05). No statistically significant differences were found among the other groups (p = 0.49).


CONCLUSIONS
The time point of irradiation can have an adverse effect on bond strength, depending on the type of adhesive material.
Bulucu
Bilinç
B
Department of Operative Dentistry, Ondokuz Mayis University, Faculty of Dentistry, Samsun, Turkey. bbulucu@omu.edu.tr
Yesilyurt
Cemal
C
Cakir
Saban
S
Meydan
Ahmet Deniz
AD
D000704:Analysis of Variance; D001840:Dental Bonding / Q000379:methods*; D003804:Dentin / Q000737:chemistry / Q000528:radiation effects*; D017220:Dentin-Bonding Agents / Q000737:chemistry / Q000528:radiation effects*; D006801:Humans; D011109:Polymethacrylic Acids / Q000737:chemistry / Q000528:radiation effects*; D019279:Resin Cements / Q000737:chemistry / Q000528:radiation effects*; D033081:Shear Strength
C438313:Clearfil SE Bond; D017220:Dentin-Bonding Agents; D011109:Polymethacrylic Acids; C425843:Prime and Bond NT; D019279:Resin Cements