All samples from each subject throughout the study (n=12: 8 GCF's - comprising 1 pooled from deep sites & 1 pooled from shallow sites @ each of 4 visits & 4 plasma samples) will be assayed on the same day and under the same laboratory conditions, in duplicate (total = 24 per subject). Each day samples from a test group 1 subject, a test group 2 subject and a control subject will be run. All assays will be completed in 10-12 hours of laboratory time per day and over 20 laboratory days (72 assays per day & 36 standards = 108 assays per day).