Fig. 3

Healthy site calculus microbial profile differs from plaque independent of sample age. a Principal component analysis (PCA) of plaque and historic healthy site calculus cluster samples by type. b Distinct species are significantly more abundant in plaque and historic healthy site calculus. c Microbial profile differences between plaque and historic healthy site calculus are sufficient for discrimination of sample types by sparse partial least squares-discriminant analysis (sPLS-DA). Ellipses indicate 95% confidence intervals. d PCA clusters plaque and modern healthy site calculus distinctly. e Microbial profile differences between plaque and modern healthy site calculus are sufficient for discrimination of sample types by sPLS-DA. Ellipses indicate 95% confidence intervals