Effect of treatment concentration on lipopolysaccharide affinity for two alloys

This study compared gram-negative bacterial lipopolysaccharide (LPS) adherence to and elution from a Type III gold and a Nisingle bondCrsingle bondBe alloy using Escherichia coli LPS. One-half of the specimens of each alloy were pre-treated with 500 μg non-radiolabeled E. coli LPS for 24 h at 37°C. All disks were then incubated with 0.15, 15 or 150 μg radiolabeled E. coli LPS for 24 h at 37°C. To evaluate radiolabeled LPS elution, specimens were transferred to LPS-free water and incubated for 24 h at 37°C. The elution scheme, which consisted of 24 h incubations and subsequent transfer to new LPS-free water, continued for up to 96 h total elution. Radiolabeled LPS adherence and elution was determined through liquid scintillation spectrometry. Control disks not treated with LPS were evaluated throughout the study with an enzymatic assay to ensure that extraneous LPS contamination did not occur. A multifactor ANOVA (p = 0.05) was used to evaluate differences in adherence to alloy specimens based upon alloy type, pretreatment status and [3H]LPS concentration. A repeated measures analysis ANOVA (p = 0.05) was used to evaluate differences in elution patterns among groups over time. Least square means were compared in case of significant effects. Toxin uptake at each treatment concentration was significantly different from the other treatment concentrations. In addition, significantly greater amounts of [3H]LPS eluted from the non-pretreated Nisingle bondCrsingle bondBe alloy following the 0.15 and 15 μg radiolabeled [3H]LPS treatment, whereas no difference in elution was found among experimental groups following the 150 μg [3H]LPS treatment. E. coli LPS, an LPS type representative of enteric bacteria common to the gingival sulcus, has differing affinities for the alloys. This affinity difference could influence periodontal inflammatory processes, thereby resulting in differing tissue responses adjacent to dental restorations fabricated from these materials. The interaction of other LPS types with these alloys could differ.