The purpose of this study was to assess the antibacterial efficacy of incorporating catechins into 4-META/MMA-TBB resin against Streptococcus mutans and to measure the shear bond strength of a metal bracket bonded to enamel using catechin-incorporated with 5% 4-methacryloyloxyethyl trimellitate anhydride (4-META)/methyl methacrylate (MMA)-tri-n-butyl borane (TBB) resin (catechin-resin). Catechin-resin disks were incubated with the bacterial suspension at 37°C for 24 h. The bacterial counts (colony forming units) of the disk and the suspension were determined separately. Catechin release from catechin-resin was monitored. The catechin-containing composites were used to bond metal brackets to human premolars pretreated with self-etching primer. After the bonded samples were immersed in water at 37°C for 24 h, shear bond strength was measured.
The most significant antibacterial activity was observed in (-)-epigallocatechin gallate-resin disk and (-)-epigallocatechin gallate-resin-treated bacterial suspension when compared with the control. Catechin was released from catechin-resin during 6 week immersion in deionized water. (-)-Epicatechin gallate, (-)-epigallocatechin and (-)-epigallocatechin gallate showed a large amount of catechin release. Only significant differences was detected in bond strength between the control and (-)-epigallocatechin gallate. The addition of (-)-epigallocatechin gallate to 4-META/MMA-TBB resin confers an antibacterial effect while retaining sufficient bond strength.