Prostaglandin E2 concentrations in gingival crevicular fluid: observations in untreated chronic periodontitis.

OBJECTIVES: We set out to monitor gingival crevicular fluid prostaglandin E2 (GCF-PGE2) concentrations longitudinally in a cohort of subjects with chronic periodontitis, given that we had noted an unexplained trend for GCF-PGE2 concentrations to gradually increase in control groups and placebo populations in previously published clinical trials.
MATERIAL AND METHODS: 41 adults with moderate-severe chronic periodontitis were recruited. GCF samples were collected from 8 test sites (with 5-8 mm probing depths and attachment loss) every 30 days for 150 days, and assayed for PGE2. Clinical measurements (probing depths, attachment levels, bleeding on probing) were recorded at days 0 and 150.
RESULTS: A gradual and statistically significant increase in GCF-PGE2 concentrations was observed over the course of the study, from 40.3 ng/ml to 83.1 ng/ml (p<0.001). When data were expressed as absolute PGE2 content, a similar statistically significant increase from baseline to day 150 was observed (p<0.001). GCF volumes did not vary significantly during the study (p>0.05). Over the same time period, no statistically significant changes in clinical parameters were recorded, with the exception of mean probing depths, which decreased slightly from 5.73 mm to 5.51 mm (p<0.05).
CONCLUSION: A trend for gradually increasing GCF-PGE2 concentrations in the absence of any clinical signs of disease progression was noted in a group of patients monitored longitudinally. We suggest that this phenomenon is to be expected in longitudinal clinical trials, and propose a new model for the role of PGE2 in the pathogenesis of periodontal destruction. We feel that if GCF mediators are to be monitored in clinical studies, then both concentrations and absolute mediator content should be calculated, and a standardised sampling protocol should be employed.