Morphotypes of the subgingival microflora in diabetic adolescents in Finland

The morphotypes of the subgingival microflora from 85 12 to 18-year-old Finnish adolescents with insulin-dependent diabetes mellitus (IDDM) were studied in Gram- and Rhodes-stained smears. A comparison was made with subgingival plaque samples from paired age- and sex-matched healthy controls. Significant differences were found in the distribution of the morphotypes. The microflora in the IDDM patient group contained significantly lower proportions of Gram-positive and Gram-negative cocci and total Gram-positive bacteria and higher proportions of Gram-negative rods, fusiforms, and total Gram-negative bacteria. In the Rhodes-stained samples, the patients had more straight and curved rods and less fusiforms than the controls. The proportions of spirochetes and flagellated bacteria were almost identical in both groups. The clinical periodontal status of the subjects had been reported in a separate study. In spite of similar Plaque Index scores, the patients had more gingivitis than the controls. This finding may be explained by the distribution of morphotypes: more Gram-negative rods and total Gram-negative bacteria (periodontally more pathogenic forms) in the diabetic patients.