Patterns of attachment loss in advanced periodontitis patients monitored following initial periodontal treatment

2 main concepts seem to exist for the progression of periodontitis: (1) a slow continuous process of attachment loss; (2) periodic bursts of activity followed by quiescence or remission. This study addresses this problem and presents data for 69 sites having experienced a net loss of probing attachment amounting to greater than or equal to 3.0 mm over 42 months. The sites originated from 16 adult patients monitored after nonsurgical treatment of advanced chronic periodontitis. Probing attachment level recordings were obtained every 3rd month. The sequential probing attachment level data for each site were smoothed using cubic splines. Subjective evaluation of the raw and the smoothed data from the study sites suggested that the majority of the sites seemed to lose probing attachment in a continuous fashion, and over periods of 12 months or more. The smoothed curves were subjected to principal components analysis, which allowed the 69 sites to be ordered according to curve similarity. Nonparametric runs test failed to show that the shape of the curves for the sites was significantly associated with any of the following characteristics: patient, tooth type, tooth surface, initial probing depth, bleeding frequency, occurrence of suppuration, or a combination of inflammatory characteristics of sites.