Decision making in periodontal therapy

. 7 patients completed 2 years of observation following initial therapy. Triplicate probing measurements were used to identify sites with ≥ 1 mm of probing attachment change between any 2 of the following time points; immediately pre‐instrumentation; immediately post‐instrumentation; 3 months; 12 months and 24 months. 24% of sites lost probing attachment directly due to instrumentation. 12% of sites lost probing attachment at 24 months compared to pre‐instrumentation, but over 1/3 of these lost attachment at the time of instrumentation. 47 sites lost probing attachment from post‐instrumentation to 24 months. 22 of these sites were shallow buccal or lingual sites and their attachment apparatus may have remodelled. The initially deeper of these sites displayed other clinical features more consistent with inflammatory periodontitis. Sites that initially gained probing attachment due to treatment but which later lost were identified. These sites may have had a reversal of the enhanced epithelial adaption. 17 other patients were monitored over a period of 31/2 years and sites losing probing attachment were identified using linear analysis of regression. The diagnostic predictability of clinical signs to reveal probing attachment loss at 31/2 years was calculated. In general, predictability values improved with increasing time interval. Increase in probing depth, particularly if combined with a high frequency of bleeding, showed the highest predictability. The effect of therapy on probing attachment levels should be considered in the identification of sites with probing attachment loss. Persistent bleeding, combined with high residual probing depths or increase in probing depth, may be a useful adjunct to probing attachment loss in identifying diseased sites.