['The aim of this study was to investigate the association of serum vitamin B12 with the progression of periodontitis and risk of tooth loss in a prospective cohort study.', 'In the Study of Health in Pomerania, 1648 participants were followed from 2002-2006 to 2008-2012 (mean duration 5.9 years). Serum vitamin B12 was measured by chemiluminescent enzyme immunoassay. Probing pocket depth (PD) and clinical attachment loss (CAL) were measured to reflect periodontal status on a half-mouth basis at each survey cycle. Tooth numbers are based upon a full-mouth tooth count.'] Is serum vitamin B12 inversely associated with periodontal progression and risk of tooth loss : a prospective cohort study?