Effect of Epigallocatechin-3-galate on the Preservation of Resin-dentin Bond Strength

Objectives: To evaluate the effect of different concentrations of EGCG in the immediate and 6-month periods on resin-dentin bond strength. Methods: Twenty four unerupted caries-free human third molars were used. Occlusal enamel was removed using a #120-grit silicon carbide paper mounted to an electric polishing machine to expose a flat coronal dentin surface. The teeth were divided into 4 groups according to the concetrationof EGCG used for dentin pretreatment. The solutions were used to re-hydrate dentin after acid-etching and before bonding application with Single Bond™ 2 (3M/ESPE): G1) distilled water, either EGCG at G2) 0.02%, G3) 0.1% or G4) 0.5%. Resin composite build-ups were bonded to sectioned teeth. Teeth were stored in distilled water at 37°C for 24h and cut into dentin-composite specimens (cross-sectional area:1mm2). Half of those specimens were immediately tested, while the remaining specimens were stored in sodium azide at 37°C for six months. Each bonded stick was subjected for microtensile bond strength (MTBS) in an Instron machine at cross-head speed of 0.5mm/minute. Data were subjected to Two-Way ANOVA and Student-Newman Keuls post-hoc test (p<0.05). Results: Mean (SD) MTBS values (in MPa) were as follow: Immediate period - G1 34.17(7.75) A,a; G2 31.39(7.82) A,a; G3 34.75(9.14) A,a ; G4 27.11(7.78) B,a. In 6-month period - G1 27.67(6.98) A,b; G2 31.75 (10.58) AB,a; G3 35.98(10.90) B,a; G4 31.18 (9.29) AB,a. Different capital letters indicate significant difference in the same period and different lower letters indicate significant difference between periods. Conclusion: All concentrations of EGCG preserved dentin bonds for at least 6 months. EGCG at 0.1% may be applied with the tested etch&rinse adhesive system. Acknowledgements: CNPq 472611/2009-7, CICYT/FEDER MAT2008-02347/MAT, JA-P07-CTS-2568 and JA-P08-CTS-3944. -->