The natural history of periodontal disease-Part 2: In populations with access to dental care: The Studies of Health in Pomerania (SHIP)

In this descriptive analysis of the 21-year follow-up data from the SHIP-START cohort and the 7-year follow-up data from the SHIP-TREND cohort, we report the progression of clinical attachment levels (CAL), age effects on CAL change, and a detailed description of CAL progression and remission. At baseline, 4307 and 4420 persons participated in SHIP-START and SHIP-TREND, respectively. At the final follow-up, 1181 and 2507 subjects were available for evaluation, respectively. In SHIP-START and SHIP-TREND participants, the mean CAL progressed by 0.04 and 0.02 mm/year, respectively. The older the participants were, the lower the average annual change in mean CAL (from 0.043 to 0.031 mm/year); annual tooth loss was 0.11-0.14 teeth/year. When participants were ranked according to their annual change in mean CAL, remission was more frequently observed in older subjects. To correctly understand the data, it is important to realize that selection bias due to dropouts during follow-up favored younger and more health-conscious persons. In addition, extraction of severely periodontally compromised teeth during follow-up biased the progression towards zero. Another explanation for these low CAL progression rates is that most sites had little or no change in CAL; this means that CAL progression was partly offset by CAL remission. Therefore, changes in mean CAL do not adequately describe the temporal course of periodontitis. Older age was not a risk factor for CAL progression in either cohort.