Dark field microscopy of the subgingival microflora in insulin-dependent diabetics

The subgingival microflora was assessed by means of dark field microscopy in 106 pockets of 47 subjects with long-term insulin-dependent diabetes mellitus (IDD). The microbiota of 55 healthy sulci (probing depth < 4 mm) and 51 periodontally diseased (probing depth > or = 4 and 6 mm) pockets were analyzed. The mean duration of the IDD of the diabetic subjects was 23.7 years (range from 10 to 41 years). The diabetic patients, aged 30-65 years, were under medical treatment at the III Department of Medicine, University of Helsinki Central Hospital, and at 2 clinics of the Helsinki Health Centre. Based upon their long-term medical records, 26 subjects were assessed to have poorly controlled insulin-dependent diabetes mellitus (PIDD) and 21 had controlled insulin-dependent diabetes (CIDD). The PIDD subjects exhibited higher mean blood glucose levels (12.9 +/- 4.6 mmol/l, mean +/- S.D.) than the CIDD subjects (7.9 +/- 3.6 mmol/l) (p < 0.001, t-test). The mean glycosylated hemoglobin HBA1 (HBA1c) levels were 11.2 +/- 4.6% (10.3 +/- 1.2%) and 8.8 +/- 1.8% (7.7 +/- 1.4%) for PIDD and CIDD subjects, respectively. These differences were statistically significant (p < 0.01 and p < 0.001, t-test). For each individual, site-specific recordings were made for plaque index and bleeding index scores, probing depth, loss of attachment and radiographic loss of alveolar bone. Dark field microscopy analysis of the presence of spirochetes, motile rods, cocci, non-motile rods, filaments and fusiforms was performed in the total of 106 pockets. According to the results of the dark field microscopy, the % of spirochetes and motile rods in the periodontally diseased pockets was significantly higher in the PIDD than in the CIDD subjects (9.2 +/- 13.4% and 10.8 +/- 14.3% versus 4.0 +/- 5.2% and 3.1 +/- 3.2%, p < 0.01 and p < 0.001, chi 2-test, respectively). Moreover, the PIDD subjects had lower mean %s of coccoid cells in periodontally diseased sites than the CIDD subjects (52.1 +/- 20.8% versus 60.7 +/- 9.0%, p < 0.001, chi 2-test).