Microleakage of resin-based liner materials and condensable composites using filled and unfilled adhesives

To evaluate the efficacy of differing resin based liner materials in reducing microleakage.

80 freshly extracted caries-free human premolars and molars were used. MO/DO Class II standardized preparations were performed with the gingival margin placed 1 mm above the CEJ. Teeth were randomly divided into two groups; each one was divided into four subgroups (A-B-C-D for Group 1 and E-F-G-H for Group 2). Each prepared tooth was etched with 32% H3PO4 (Uni Etch); in Group 1, one coat of One Step and in Group 2, two coats and two cures of Prime & Bond NT adhesives were applied. In each group 1 mm layer of three different liners was used: A2 Heliomolar RO for A and E; A2 Heliomolar Flow for B and F; A2 Bisfil 2B for C and G. No liner was used for D and H subgroups. Teeth were then restored using 2 mm increments of Pyramid A2 Dentin and A1 Enamel and cured with a VIP curing light. Teeth were thermocycled x500 between 5 degrees C and 55 degrees C with a dwell of 30 seconds and then placed in a 0.5% methylene blue dye solution for 24 hours at 37 degrees C. Samples were sectioned longitudinally and evaluated for microleakage at the gingival margin under a stereomicroscope at x20 magnification. Dye penetration was scored using an Ordinal Scoring System where 0= no penetration; 1= enamel penetration; and 2= dentin penetration.

A Chi Square Test revealed a statistically significant difference between Group 1 and Groups 2 (P < 0.001). Group 1 yielded the most microleakage. No statistically significant difference was noted between the subgroups of each group; a statistically significant difference of B and D vs. E and H (P < 0.01 > 0.001) and B vs. G and D (P < 0.05 > 0.01) was also noted. The dentin bonding agent in Group 2 contributed to a reduction of microleakage when compared to Group 1.