EFFECT OF TREATMENT CONCENTRATION ON LIPOPOLYSACCHARIDE AFFINITY FOR 2 ALLOYS

Objective. This study compared gram-negative bacterial lipopolysacchar ide (LPS) adherence to and elution from a Type III gold and a Ni-Cr-Be alloy using Escherichia coil LPS. Method. One-half of the specimens o f each alloy were pre-treated with 500 mu g non-radiolabeled E. coli L PS for 24 h at 37 degrees C. All disks were then incubated with 0.15, 15 or 150 mu g radiolabeled E. coil LPS for 24 h at 37 degrees C. To e valuate radiolabeled LPS elution, specimens were transferred to LPS-fr ee water and incubated for 24 h at 37 degrees C. The elution scheme, w hich consisted of 24 h incubations and subsequent transfer to new LPS- free water, continued for up to 96 h total elution. Radiolabeled LPS a dherence and elution was determined through liquid scintillation spect rometry. Control disks not treated with LPS were evaluated throughout the study with an enzymatic assay to ensure that extraneous LPS contam ination did not occur. A multifactor ANOVA (p = 0.05) was used to eval uate differences in adherence to alloy specimens based upon alloy type , pretreatment status and [H-3]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 c ase of significant effects. Results. Toxin uptake at each treatment co ncentration was significantly different from the other treatment conce ntrations. In addition, significantly greater amounts of [H-3]LPS elut ed from the non-pretreated Ni-Cr-Be alloy following the 0.15 and 15 mu g radiolabeled [H-3]LPS treatment, whereas no difference in elution w as found among experimental groups following the 150 mu g [H-3]LPS tre atment. Significance. E. coil LPS, an LPS type representative of enter ic bacteria common to the gingival sulcus, has differing affinities fo r the alloys. This affinity difference could influence periodontal inf lammatory processes, thereby resulting in differing tissue responses a djacent to dental restorations fabricated from these materials. The in teraction of other LPS types with these alloys could differ.