Microleakage of self-etching primers after thermal and flexural load cycling

To evaluate the adhesive properties of a one-bottle self-etching primer system.

150 wedge-shaped cervical cavities on bovine teeth were restored with Clearfil Liner Bond 2 (LB), Clearfil Liner Bond 2V (LV) or Clearfil SE Bond (SE), according to the manufacturer's instructions. Twenty specimens of each adhesive system were finished 15 mins after light curing and 30 specimens were finished after a 24-hr storage period in water. From each group, 10 restorations were immediately immersed in 0.5% basic fuchsin solution and kept there for 24 hrs to examine microleakage. The other 10 restorations were thermocycled (5-60 degrees C, 15 s dwell time, 5,000 cycles), and then immersed in the dye solution. The remaining 10 specimens of the 24-hr storage group were subjected to flexural load cycling (0.5 mm labio-lingual displacement at the incisal edge, 10,000 cycles, 1 cps) prior to immersion in the dye solution. The data was analyzed using the Mann-Whitney U-test and the Kruskal-Wallis test. The tensile bond strengths of the adhesive systems to bovine enamel and dentin were also determined. The data was analyzed using the Student's t-test and ANOVA. In addition, SEM examinations were made to evaluate the effects of self-etching primers on enamel and dentin surfaces.

LV and SE showed significantly better marginal sealing than LB (P<0.05). The marginal integrity of SE did not deteriorate even after immediate finishing, thermal stresses or flexural loads. There were no significant differences in bond strengths among the adhesive systems tested. All adhesive systems showed similar bond strengths to enamel and dentin. The enamel etching patterns using LV and SE systems were obscure and difficult to assess. Although the smear plugs were not fully removed, no smear layer was observed on the treated dentin surfaces, regardless of the self-etching primer system used.

Clearfil SE bond could possibly improve the clinical performance of cervical cavities.