Analysis of Microbial Biofilms on Different Dental Material Surfaces

Objectives: Microorganism induced stomatitis, an inflammation of the oral mucosal tissue that can further progress to severe oral or systemic infections, is a widespread problem in denture-wearing patients according to clinical observations. Little research has been conducted in this area and few products are available to control the problem. We have formed a collaborative research team between GlaxoSmithKline and UCLA to address this problem. This study is supported by funds from GSK. Methods: We developed a high-throughput in vitro biofilm model system to allow for growth of a variety of relevant microbial biofilms on surfaces made of real denture material, porcelain and hydroxyapatite. The colonization behavior of single species biofilms of key oral pathogens Candida albicans and Streptococcus mutans, as well as saliva-derived biofilms that mimic dental plaque, was analyzed on these surfaces. We then utilized this study system to assess the efficacy of Polident® cleansers (GSK) against various biofilms. Results: S. mutans exhibited similar affinity in biofilm formation on denture, porcelain and hydroxyapatite materials, while salivary bacteria exhibited preferential adherence to hydroxyapatite material. Interestingly, C. albicans adhered the least to hydroxyapatite and displayed significantly higher biomass accumulation on the other surfaces tested including denture material and porcelain. Using this newly established study system, we also found that the cleansers were able to kill at least 97% of the biofilm cells in a short 5 minutes exposure period. Conclusion: The fact that many results described above are consistent with previous clinical observations validates the usefulness of this new biofilm study system. Furthermore, the study confirmed the efficacy of the cleansers against various oral pathogens and biofilms in a short 5 minutes exposure period.