Degree of polymerization and TBS of self-etching adhesives

Objectives: To evaluate the effect of curing light distance on polymerization characteristics and the tensile bond strengths (TBS) of self-etching adhesives.

Methods: FT-IR measurement: Degree of photo-polymerization (DP) of two self-etching adhesives [Dual-curing adhesive: Brush&Bond (B&B, Parkell); Photo-curing adhesive: AQ Bond Plus (AQP, Sun Medical)] was measured by FT-IR. Infrared absorbance was measured before and after irradiation at various distances: 1, 5, 10, 15 and 20 mm. Polymerization was calculated in percentage by comparing the ratio of C=C (1640 cm^-1) and C=O (1710 cm^-1). TBS testing: Bovine dentin samples were polished with 180-grit SiC under water irrigation. B&B or AQP was applied to the surface according to manufacturer's instructions. All samples were photo-polymerized for 5 seconds in a precise irradiation distance: 1, 5, 10, 15 and 20 mm. A mold (ø4.8mmx0.7mm) was filled with dual-curing resin (Absolute-Dentin, Parkell), and then placed onto the bonded surface. Specimens were immersed in water at 37°C for 24 hours before TBS testing. TBS values were analyzed using two-way ANOVA and scheffe's test (p=0.05).

Results: Results (Table) indicated that DP values of two adhesives decreased with an increase in the irradiation distance although TBS values did not have a dependence of the irradiation distance.

Conclusion: It was indicated that TBS values were not dependent on photo-polymerization of these adhesives. Both B&B and AQP were containing same chemical agents which could cure the resin without a light irradiation in their particularly provided brushes or sponges. Therefore, it was considered that TBS values of them were not decreased in case of low photo-polymerization.

Values with same letters are not significantly different (p>0.05).