Relationship between some subgingival bacteria and periodontal pocket depth and gain or loss of periodontal attachment after treatment of adult periodontitis

We studied the association between post-treatment periodontal disease activity and subgingival Bacteroides gingivalis, Bacteroides intermedius, spirochetes and motile rods. 20 adults, 22-62 years, with moderate-to-severe periodontitis participated in a split-mouth treatment study. All individual quadrants received supragingival cleaning and in addition, subgingival scaling and a NaHCO3-NaCl-H2O2 slurry, subgingival scaling alone, slurry alone, or no subgingival treatment. Post-treatment periodontal disease status was determined over a period of 12 months by changes in probing periodontal pocket depth and probing periodontal attachment level. Subgingival specimens obtained by paper point-sampling were evaluated for B. gingivalis and B. intermedius using indirect immunofluorescence and for spirochetes and motile rods using bright light phase contrast microscopy. A total of 142 periodontitis lesions representing all 4 quadrants of the 20 subjects were studied. The relationship between clinical data and bacteria was analyzed using logistic regression. The probability of the study organisms being present in subgingival sites at 3 to 6 months after treatment increased with increased residual pocket depth. The presence of B. gingivalis showed a strong positive association (p less than 0.004) with loss of periodontal attachment. A significant association was also found for spirochetes (p less than 0.008) but not for motile rods (p greater than 0.35) or B. intermedius (p greater than 0.13). Similar results were obtained at 12 months after therapy, except that the presence of motile rods was significantly associated with loss of periodontal attachment (p less than 0.03). Caution must be exercised when using B. gingivalis or spirochetes to evaluate treatment efficacy. If the presence of these organisms was utilized to indicate progressing periodontitis, many active lesions could be identified, and only 1 to 17% and 13 to 43% of sites in remission at 3-6 months after therapy would be expected to harbor B. gingivalis and spirochetes, respectively. The consequences of treating periodontal sites in remission would mainly be limited to cost and inconvenience. However, since several active periodontitis lesions did not reveal the organisms, treatment decisions based solely on the absence of the organisms may result in the omission of needed therapy. As a practical consideration, periodontal treatment should be continued as long as B. gingivalis and maybe spirochetes are detectable in the subgingival microflora. In the absence of these organisms, and until additional periodontal pathogens have become known, the decision to continue or conclude periodontal therapy must b