[Effects of scaling and root planing on clinical parameters and bacterial flora in periodontal pockets. 2. Correlation between decrease of probing pocket depth and pretreatment status].

Scaling and root planing is one of the most fundamental and effective procedures in periodontal therapy. The purpose of this study was to investigate statistically whether clinical or microbiological parameters before treatment are related to changes in probing pocket depth (PD). Two kinds of numerical values represented changes in PD. One was pocket difference (A-B: A; PD before the treatment and B; PD after treatment) and the other was rate of pocket decrase [(A-B)/A x 100]. Twenty four sites in six patients with periodontal pockets deeper than 4 mm were selected for this study. Clinical parameters such as PD, probing attachment level (PAL), gingival crevicular fluid (GCF) volume, gingival bleeding index (GBI) and suppurative index (SI) were recorded at each site. Subgingival plaques sampled at the same site were evaluated by phase contrast microscopy. The results obtained were as follows: 1. Of all the clinical parameters changes in PD were most positively correlated with PD before treatment. 2. The microbiological approach revealed that total bacterial count divided by PD value was more negatively correlated with changes in PD than total bacterial number. It was further, revealed that numbers of rods and motile bacteria were more closely correlated with changes in PD than the counts of bacterial groups. At sites where coccoid cells were relatively dominant, PD tended to decrease readily. Motile bacteria, on the other hand, exhibited just the opposite relationship. These results suggest that periodontal treatment should be more effective in periodontal pockets harboring both smaller numbers of rods and motile bacteria.