Samples GCF samples will be collected (30s) using Periopaper strips from the mesio-buccal aspects of 3 deep (>6mm) and 3 shallow (<3mm) molar sites per subject as described in appendix 1. Volumes will be read on a pre-calibrated Periotron 8000 according to standard methodologies 19. Each trio of sample strips will be collected into 400ul PBS/BSA buffer and snap frozen under liquid nitrogen until assay 13.