Inflammatory and Microbial Biomarkers Associated with Experimental Gingivitis Clinical Responses

OBJECTIVE: The goal was to identify baseline biomarkers as possible candidates for predicting clinical responses during the induction of experimental gingivitis.

MATERIAL AND METHODS: Experimental gingivitis was induced in 24 subjects for 21 days using intraoral stents. Weekly samples were collected for GCF multiplex analyses of 33 biomarkers including cytokines, matrix metalloproteinases (MMPs) and adipokines; and plaque for DNA checkerboards to identify 14 organisms. Cluster analyses were performed to create clinical phenotypes based upon changes in GI and PD and a GI*PD interaction comparing day-21 to baseline. Statistical testing for changes in GCF biomarker levels was performed by ANCOVA adjusting for both patient (non-stent) and baseline differences, considering p<0.05 as significant.

RESULTS: Three clinical phenotype clusters emerged comparing changes between baseline to Day21. All showed increases in plaque scores. Cluster: 1) No clinical change, 2) Increased BOP and GI, and 3) Increased BOP and PD. Cluster 1 showed lowest baseline values for IL-1a and IL-1b that significantly increased at day21. Cluster 2 and 3 showed higher baseline IL-1a and IL-1b that tended to increase at Day21 non-significantly. Cluster 2 showed significant decreases in MIP-1b and serpin E1. Cluster 3 demonstrated significant decrease in IL-8, MCP-1, MIP-1b and MMP-1 and MMP-13. At baseline the total counts were approximately equal across all three clusters and there were no significant differences in the magnitude of changes at Day21 in the microbial counts of 14 organisms comparing the 3 clusters. However, at baseline cluster 1 had less than one-tenth the total count of red complex, as compared to cluster 2 (p=0.04) and cluster 3 (p=0.46).

CONCLUSION: Differences in clinical responses during gingivitis induction were associated with differences in baseline flora and changes in GCF inflammatory biomarkers.

Work supported by Philips Oral Healthcare and RR-00046.