Endotoxin Affinity for Provisional Restorative Resins

PURPOSE: This study compared the relative affinity of Porphyromonas gingivalis and Escherichia coli endotoxin, bacterial cell envelope lipopolysaccharide (LPS), for three provisional resins. MATERIALS AND METHODS: As-polymerized and pumiced polymethyl methacrylate and polyethyl methacrylate resin discs were exposed to 1,000 endotoxin U/mL P. gingivalis or E. coli LPS in water for 24 hours at 37 degrees C, whereas control discs were placed in LPS-free water. LPS-treated discs were transferred at 24-hour intervals to fresh, LPS-free water for up to 96 hours, and the incubated eluates were tested for the presence of LPS. RESULTS: Initial adherence of P. gingivalis LPS to as-polymerized and pumiced-finish resin was a function of resin type, but surface characteristics modified adherence levels. When steady rates of elution were reached at 72 to 96 hours, as-polymerized specimens released significantly greater LPS levels than pumiced samples. Comparison of initial adherence of P. gingivalis and E. coli LPS with pumiced resins showed that adherence was based on a combination of LPS and resin type. P. gingivalis LPS had a greater relative affinity for polyethyl methacrylate, and E. coli LPS has a greater relative affinity for polymethyl methacrylate. Regardless of resin type, P. gingivalis LPS eluted at levels greater than E. coli LPS. CONCLUSIONS: The affinity of LPS for provisional resins seems to be a function of selective interactions based on the chemical nature of the resin, the surface finish of the resin, and the molecular structure of the LPS.