The Composition of the Subgingival Microbiota After Periodontal Therapy

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Abstract
The purpose of the study was to determine the composition of the microbiota in periodontally diseased pockets by dark field microscopy prior to treatment, after scaling and root planing, and after periodontal surgery. Eighteen patients with untreated chronic periodontitis were selected. Preoperative or baseline clinical data included Plaque Index (PlI), Gingival Index (GI) and Probing Depth (PD). Subgingival microbial debris from the surface with the deepest probing depth in each of the six sextants was collected and the pooled microbial sample was examined by differential dark‐field microscopy. The relative proportions of bacterial forms were classified into four groups: coccoid cells, motile rods, spirochetes and others. The patients were instructed in oral hygiene and received several sessions of scaling and root planing, some of these in conjunction with occlusal therapy. The clinical and microbial status was reevaluated prior to the surgical treatment phase. At least 6 weeks after the last surgical intervention aimed at facilitating access for debridement and pocket reduction, the clinical data and microbial composition were recorded again. The results indicated a significant increase in the mean percentage of coccoid cells and a significant decrease in the proportions of spirochetes and motile rods from baseline to postinitial therapy and from postinitial therapy to postsurgery. Some differences were noted between subjects in their response to therapy. Although 16 of 18 cases showed a decrease in the percentages of spirochetes and motile rods as a result of therapy, two patients showed an increase in the proportions of spirochetes and motile organisms and a decrease in the proportion of coccoid cells. These microbial changes were accompanied by a deterioration of the clinical status of these patients. In general, GI and P1I scores and PD measurements varied directly with the proportions of spirochetes or motile rods, and inversely with the proportion of coccoid cells. The greatest clinical improvement with respect to P1I and GI scores and PD occurred between baseline and the completion of initial therapy. Relatively little if any change in these clinical parameters was detectable in the interval betweens the completion of initial therapy and the postsurgical phase, despite the continued shift in bacterial composition from a flora associated with diseased sites toward one associated with periodontally healthy sites.
Funding Information
  • U.S. Public Health Service (DE‐02636)
  • University of Pennsylvania (DE‐40759)