Longitudinal assessment of risk factors for periodontal disease is necessary to provide evidence that a putative risk factor or risk indicator is a true risk factor. The purpose of the present study was to explore longitudinally a variety of markers as possible periodontal risk factors in subjects with little or no periodontal disease at baseline. 415 subjects with mild or little periodontal disease were examined: medical and dental history; socioeconomic profile, clinical measurements, microbial samples and radiographic assessment of bone height were performed at baseline, and at a follow-up examination 2 to 5 years later. Mean probing pocket depth (PPD) at baseline was 1.99+/-0.37 mm while mean overall change was 0.1 mm which amounts to an annual rate of 0.04 mm. Overall mean clinical attachment level (1.75+/-0.6 mm) at baseline resulted in mean attachment change of 0.28 mm (0.12 mm annually). Alveolar crestal height (ACH) at baseline (mean 2.05+/-0.85 mm) resulting in a mean net loss of 0.1 mm. Approximately 10% of all sites presented for the second visit with attachment loss exceeding the threshold (4.4% annually), while only 2.2% of all sites exhibited attachment gain (0.88% annually). Older individuals exhibited greater mean bone loss but the least amount of attachment loss. Current smokers exhibited greater disease progression compared to non-smokers. Tooth morbidity (0.17 teeth/patient/year) was associated with greater baseline CAL and ACH loss, and an assortment of systemic conditions. Subjects who harbored Bacteroides forsythus (Bf) at baseline had greater loss in ACH; likewise, these subjects experienced greater proportions of losing sites and twice as much tooth mortality compared to Bf-negative patients. Baseline clinical parameters correlated strongly with the outcome, i.e., subjects with deeper mean pocket depth at baseline exhibited greater increase in pocket depth overtime; while subjects with greater attachment loss at baseline exhibited greater attachment loss between the 1st and 2nd visits.