Effect of green tea extract on bonding durability of an etch-and-rinse adhesive system to caries-affected dentin

Journal of Applied Oral Science

J. Appl. Oral Sci. vol.24 no.3 Bauru May./June 2016

http://dx.doi.org/10.1590/1678-775720150518 

ABSTRACT

Objective

Green tea extract has been advocated as a matrix metalloproteinase (MMP) inhibitor; however, its effect on bond durability to caries-affected dentin has never been reported. Thus, the aim of this in vitro study was to evaluate the effect of two MMP inhibitors (2% chlorhexidine and 2% green tea extract), applied after acid etching, on bond durability of an etch-and-rinse adhesive system to caries-affected dentin.

Material and Methods

Occlusal enamel was removed from third molars to expose the dentin surface, and the molars were submitted to a caries induction protocol for 15 days. After removal of infected dentin, specimens were conditioned with 37% phosphoric acid (15 seconds) and randomly divided into three groups, according to the type of dentin pretreatment (n=10): NT: no treatment; GT: 2% green tea extract; CLX: 2% chlorhexidine. The etch-and-rinse adhesive system (Adper™ Single Bond 2, 3M ESPE, St. Paul, MN, USA) was applied according to the manufacturer's instructions, and composite resin restorations were built on the dentin. After 24 hours, at 37°C, the resin-tooth blocks were sectioned perpendicularly to the adhesive interface in the form of sticks (0.8 mm² of adhesive area) and randomly subdivided into two groups according to when they were to be submitted to microtensile bond strength (μTBS) testing: immediately or 6 months after storage in distilled water. Data were reported in MPa and submitted to two-way ANOVA for completely randomized blocks, followed by Tukey’s test (α=0.05).

Results

After 24 hours, there was no significant difference in the μTBS of the groups. After 6 months, the GT group had significantly higher μTBS values.

Conclusion

It was concluded that the application of 2% green tea extract was able to increase bond durability of the etch-and-rinse system to dentin. Neither the application of chlorhexidine nor non-treatment (NT - control) had any effect on bond strength after water storage.