Effect of cholesterol esterase on durability of resin-dentin bond

Effect of cholesterol esterase on durability of resin-dentin bond

C. Yiu, N. Hiraishi, N.M. King and F,R. Tay

Background:  Cholesterol esterases have been shown to degrade the monomer components of composite resins. Objective: To evaluate the effect of cholesterol esterase on microtensile bond strengths of etch-and-rinse and self-etch adhesives to dentin after 12 months of aging in artificial saliva. Methods: Flat dentin surfaces prepared from forty-eight extracted caries-free human third molars were divided into two groups for bonding with a 3-step etch-and-rinse (Scotchbond Multipurpose, SCMP) or a 2-step self-etch (Clearfil SE Bond, CSE) adhesive. The adhesives were applied to dentin following manufacturer's instructions and light-cured after solvent evaporation. Composite build-up (Z250, 3M ESPE) was performed with five 1-mm increments. The bonded teeth were sectioned into 0.9 x 0.9mm beams and assigned to one of the three storage conditions: (i) artificial saliva (24 hours); (ii) artificial saliva (12 months) and (iii) artificial saliva containing cholesterol esterase (12 months). Microtensile bond strengths were evaluated and analyzed by 2-way ANOVA and SNK multiple comparison tests. Results: Significant differences were observed for the two factors "adhesive" (p=0.001) and "storage condition" (p<0.05). Interaction between these two factors was not significant (p>0.05). After 12 months of storage in artificial saliva, significant reduction in bond strength was observed in SCMP. The addition of cholesterol esterase to artificial saliva had no effect on the long-term bond strength of both adhesives to dentin. 

                                  Microtensile Bond Strength (MPa)

                                  CSE            SCMP

Artificial saliva (24 hrs)        40.16^a±5.56    35.84^a,b±5.81

Artificial saliva (12 months)     37.22^a,b±7.45   29.55^b,c±6.25

Artificial saliva and

cholesterol esterase (12 months)  36.15^a,b±5.68   26.51^c±5.86

*Values are mean±SD. Different superscripts values indicate significant differences (p<0.05).

Conclusion: Durability of resin-dentin bond was not affected by cholesterol esterase. This study is supported by HKU grants 10207821.14207.08004.324.01.