Chlorhexidine (CHX) has been shown to maintain hybrid layer morphology and bond integrity. Objectives: To evaluate the effect of incorporation of 2% CHX into experimental adhesives (R1-3) of various degree of hydrophilicity on microtensile bond strength (MTBS) to dentin. Methods: For the control groups, three ethanol-based (50 wt% ethanol/50wt% resin) experimental adhesives were prepared. For the experimental groups, 2% CHX diacetate was further added to the ethanol-solvated experimental adhesives. Flat dentin surfaces prepared from 30 extracted caries-free human third molars were etched with 37% phosphoric acid for 15 s. The experimental adhesives were generously applied to dentin and light-cured for 40 s (500 mW/cm2) after solvent evaporation. Composite build up (Z250, 3M ESPE) was performed with five 1-mm increments. After storage in water at 37oC for 24 h, teeth were cut into 0.9mm x 0.9mm beams for MTBS testing. Data were analyzed by two-way ANOVA (resin hydrophilicity and CHX) and Tukey tests (a = 0.05). Results: There was no significant interaction between “resin hydrophilicity” and “CHX”. Bond strength increased with hydrophilicity of the resins (p<0.001) and CHX had no effect on bond strength of experimental adhesives to dentin (p>0.05).
Microtensile Bond Strength (MPa) | ||
50 wt% ethanol-solvated resins | With 2% CHX | Without CHX |
Resin 1 | 20.3 ± 6.1 (41)a | 19.0 ± 5.2 (40)a |
Resin 2 | 33.0 ± 6.2 (39)b | 30.3 ± 5.9 (41)b,d |
Resin 3 | 37.4 ± 4.8 (42)c | 34.9 ± 7.1 (42)b,c |
Values are mean ± S.D. (number of specimens). Different superscripts values indicate significant differences (p<0.05).
Conclusion: The bond strength of experimental adhesives to dentin increased with hydrophilicity of the resins and was not affected by incorporation of CHX. Future experiments will examine how durable the bonds are after one year.
This study is supported by HKU grants 10207401.14207.08004.323.01 and 10207821.14207.08004.324.01