Bacteria adherence and biofilm composition into polyamide resin

Polyamide resin has been used to manufacture removable prosthesis, mainly because this product offers a good esthetic and is monomer free, besides to be lightweight. However, it has been showed that this material is easily colonized by C. albicans, but no studies about bacterial colonization on polyamide resins were found. Objective: The aims of this study were to evaluate the adherence, biofilm formation and polysaccharide composition of three bacteria on polyamide and acrylic resin. Methods: Specimens of polyamide resin (PR) and poly methyl methacrylate acrylic resin (PMMA) were prepared and had their surface roughness standardized. Two groups (n=20) were constituted. The microorganisms used were Streptococcus mutans UA159 ATCC-700610, Streptococcus sanguinis ATCC-10556 or Actinomyces naeslundii ATCC-12104. For the adherence assay, the incubation time was 1 hour, and the adhered cells were detached from the resin surface by ultrasonic waves for 10 min. The bacterial suspension was then submitted to DNA extraction using (Genomic tip 20/G, Quiagen, EUA) according to the manufacturer's instruction. The results were expressed in DNA concentration (ng/µL). The biofilms were formed during 5 days, when biomass, number of viable cells and polysaccharides content (soluble and insoluble and iodophilic polysaccharide-IPS) were evaluated. The data were analyzed by ANOVA followed by Tukey test with significant level set at 5%. Results: No statistical differences were found between the materials regarding adherence assay, biomass total microorganism count, polysaccharides matrix and IPS content (p>0.05). Conclusion: The polyamide resin can be used for functional and esthetic denture rehabilitation without increasing bacterial colonization or biofilm formation when compare with PMMA. Acknowledgment: This study was supported by FAPESP # 2006/03090-7.