Effect of non-surgical periodontal therapy. VI. Localization of sites with probing attachment loss.

Incisors, cuspids and premolars in 49 patients with advanced chronic periodontitis were treated with initial, non-surgical periodontal therapy. The results were monitored by probing attachment level measurements at 6 sites of each tooth every 3rd month during a period of 24 months. A series of 9 probing attachment level measurements for each site was subjected to linear regression analysis. The slope of the regression line, the projected probing attachment loss during the 24-month interval (delta y) and the probability level of the slope were calculated for each site. 2 groups of sites with probing attachment loss were identified: group 1: sites with delta y greater than 1.5 mm and p less than 0.05; group 2: sites with delta y greater than 1.0 mm and p less than 0.05. Group 1 included 120 sites (5%) and group 2 included 265 sites (10%) of the total of 2532 available sites. In both groups, probing attachment loss was more frequently noticed for sites with an initial probing depth less than or equal to 3.5 mm than for sites with initial probing depth greater than or equal to 7.0 mm. The finding that the majority of sites with probing, attachment loss was found amongst initially shallow or moderately deep lesions may indicate attachment loss due to trauma associated with therapy rather than loss as a result of a continuing, inflammatory disease process.