Influence of PVM/MA copolymer on bacterial adherence to resin surfaces

Purpose: The aim of this pilot study was to investigate the effects of methylvinyl ether and maleic acid (PVM/MA) copolymer containing self-etch (SE) adhesive bonding agent in preventing colonization of the composite material surfaces by Streptococcus gordonii. Methods and materials: Twelve polished cylindrical composite resin discs (8mm in diameter and 2mm in thickness) were divided into two test groups: 1. SE adhesive resin (Clearfil SE Bond, Kuraray) application to the top and bottom surfaces of the discs; 2. PVM/MA containing SE adhesive resin application. For PVM/MA containing adhesive resin, 3mg PVM/MA powder was mixed in 2 drops of bonding agent of SE Bond adhesive material. The specimens were placed in 24-well microplates and sterilized by UV irradiation for 30min before incubation with bacteria. Bacterial adherence to composite surfaces was assessed by determining colony-forming units (CFU) and viewing by scanning electron microscopy (SEM). The specimens were immersed in clear and filtered whole saliva which had been collected from a single donor. After washing with phosphate-buffered saline (PBS), the specimens were placed in individual wells containing 1× 108 cells/ml of Streptococcus gordonii in PBS. Immersed specimens were incubated at 37 ◦C for 24h and washed again with PBS to remove unattached bacteria. Half of the specimens were then placed into tubes containing 1mL of PBS. The attached bacterial cells were dispersed by sonication. Serial dilutions were made and inoculated ontoBrainHeart InfusionBrothplates to determine CFU. For SEM analysis, the other half of the specimens were immersed in Karnovsky’s fixative for 24h, dehydrated, coated with gold-palladium. ANOVA and post hoc Tukey’s test were used to assess statistical differences. Results: Bacterial adherence (log CFU/mL) to PVM/MA containing SE adhesive resin-covered composite surfaces was significantly less (9.20E+02) than adherence (7.92E+03) to regular SE adhesive resin covered surfaces (p=0.05). SEM also confirmed these results showing reduced bacterial attachment to PVM/MA containing adhesive resin applied surfaces. Conclusion: The PVM/MA copolymer significantly reduces bacterial adherence to resin materials.