EFFECT OF NONSURGICAL PERIODONTAL THERAPY .5. PATTERNS OF PROBING ATTACHMENT LOSS IN NON-RESPONDING SITES

Incisors, cuspids and premolars in 33 patients with advanced chronic periodontitis were treated by plaque control and 1 single episode of supra- and subgingival debridement. Results were monitored by probing attachment level measurements for 6 sites of each tooth every 3rd mo. during 24 mo.; 1368 sites were observed. From these were selected 280 non-responding sites showing 1.0 mm or more loss of probing attachment at 24 mo. compared to baseline. Scatter diagrams of the sequence of 9 probing attachment recordings obtained during the 24 mo. study were produced for each of these 280 sites. Study of these scatter diagrams resulted in identification of 7 different patterns of probing attachment change over time. A linear pattern of gradual loss of probing attachment throughout the 24 mo. observation period was found for 73% of the non-responding sites. Of the less frequently seen patterns, 3 approximated a linear course and 3 were non-linear. Linear analysis of regression as a statistical method to determine attachment loss for individual sites seems to be suitable for sites with linear patterns and for sites approximating a linear pattern. The insensitivity of regression analysis in non-linear patterns may be acceptable if a cautious analysis is warranted.