A comparative evaluation of microbial adherence on heat activated polymethyl methacrylate denture base resin after being polished by three commercially available polishing agents

Aim: To evaluate the amount of adherence Streptococcus mutans on polished denture surface after being polished by three different polishing agents. Materials and Methods: After polymerization and finishing the samples of heat activated polymethyl methacrylate (PMMA) denture base resin were mechanically polished with pumice, tripoli and aluminum oxide paste. The surface topography was evaluated using a scanning electron microscope (SEM). Streptococcus mutans was cultured on them and after 24 hours number of adhered colonies were calculated by counting the number of colonies using florescent microscopy. Results: Roughness average (Ra)values obtained from SEM images of PMMA samples polished with tripoli, resilit, pumice and unpolished control were 0.52 µm, 0.68µm, 3.07µm and 3.45µm, respectively. Number of Streptococcus mutans colonies on samples polished with tripoli, resilit, pumice and unpolished control were 8.10 CFU/µm2, 13.20CFU/µm2, 19.90CFU/µm2 and 33.20 CFU/µm2, respectively. An increase in surface smoothness resulted in a significant decrease of adherence. (p=0.02) Conclusion: Tripoli resulted in producing the smoothest surface among all other groups while pumice gave the most rough surface. Adherence of Streptococcus mutans was least for tripoli polished samples and highest in case of those polished using pumice. As a result it was concluded that microbial adherence decreased with the increase in surface smoothness.