ABSTRACT
<p><b>OBJECTIVE</b>To observe two-year natural progression of chronic periodontitis in mild, moderate and advanced periodontitis patients.</p><p><b>METHODS</b>The periodontal status of 169 untreated chronic periodontitis patients aged from 22 to 64, were examined for two years. Periodontal measurements were performed on all teeth except the third molars and 6 sites examined for each tooth. Probing depth (PD), attachment loss (AL), and bleeding on probing (BOP) were measured at baseline, one year, and two year by a same experienced periodontist. Forty-five patients were diagnosed as having mild periodontitis, 87 with moderate, and 37 with advanced periodontitis. The changes of attachment level in these three group patients were analyzed. The site with change of AL greater than 3 mm (DeltaAL > or = 3 mm) were defined as periodontal disease activity (PDA) sites. The occurrence of PDA in three groups was compared.</p><p><b>RESULTS</b>(1) The average AL levels at 1 year and at 2 year were greater than that at baseline in mild, moderate and advanced periodontitis. (2) The percentage of sites with AL > or = 1 mm in three groups all increased from baseline to 1 year and to 2 year. (3) The occurrence of periodontal disease activity increased significantly from mild (0.14% at site level, 15.56% at subject level), moderate (0.39%, 29.89%) to advanced (0.73%, 43.24%) periodontitis patients. (4) The mean baseline AL and PD levels in active sites were greater than that in inactive sites (PD: 3.03 +/- 0.45 vs. 2.87 +/- 0.38, P < 0.05; AL: 2.25 +/- 0.93 vs. 1.77 +/- 0.90, P < 0.01).</p><p><b>CONCLUSION</b>Untreated advanced periodontitis patients were the risk population for further periodontal breakdown.</p>