CLINICAL AND MICROBIOLOGICAL FEATURES OF SUBJECTS WITH ADULT PERIODONTITIS WHO RESPONDED POORLY TO SCALING AND ROOT PLANING

In a previous report, it was shown that scaling and root planing (SRP) decreased mean pocket depth and attachment level in subjects with adu lt periodontitis, as well as the levels and prevalence of Bacteroides forsythus, Porphyromonas gingivalis and Treponema denticola. However, a subset of subjects in that study exhibited mean loss of attachment f ollowing SRP. The purpose of the present investigation was to seek cli nical and microbiological differences between subjects who responded w ell or poorly to SRP. 57 subjects with adult periodontitis were treate d by full-mouth SRP under local anaesthetic. Clinical assessments of p laque, redness, suppuration, BOP, pocket depth and attachment level we re made at 6 sites per tooth prior to and 3 months post-SRP. Attachmen t level measurements were repeated at each visit and differences in me ans between visits used to assess change. 18 subjects showed mean atta chment loss 3 months post-SRP (poor response group), while 39 showed m ean attachment level gain (good response group). The prevalence and le vels of 40 subgingival taxa in subgingival plaque samples from the mes iobuccal site of each tooth (maximum 28 sites) in each subject prior t o and 3 months post-SRP were assessed using checkerboard DNA-DNA hybri dization. The prevalence of each species was computed for each subject and averaged across subjects in the 2 treatment-response groups at ea ch visit. Differences between groups were sought using the Mann-Whitne y test. There were no statistically significant differences between th e 2 response groups in any clinical parameter prior to therapy. Subjec ts in the good response group showed more attachment level gain at sit es with baseline pocket depths of <4 mm, 4-6 and >6 mm than poor respo nse subjects. Of 40 species evaluated, A. naeslundii genospecies 2 (A. viscosus), T. denticola, C. gracilis and C. rectus were significantly higher and more prevalent pre-therapy in the good response subjects. Mean attachment level change post SRP could be predicted using multipl e linear regression with A. naeslundii genospecies 2 (A. viscosus) and T. denticola as the predictor variables (r(2)=0.373, p<0.00001). Site s that gained >2 mm of attachment post therapy showed a significant de crease in the counts of P. gingivalis (7.5+/-3.5 to 0.2+/-0.2x10(5)), T. denticola (8.2+/-3.5 to 1.8+/-1.1x10(5)) and B. forsythus (11.1+/-5 .7 to 0.3+/-0.2x10(5)). The data of the present investigation indicate that SRP is most effective in subjects and sites with high levels of the subgingival species that this therapy affects.