[Clinical study of the correlation between bad breath and subgingival microflora]

A dark field microscopic examination of subgingival microorganisms and gas chromatographic analysis of volatile sulphur compounds were employed to investigate the role of subgingival microflora in the production of bad breath. Subjects (11 female, 13 male; aged 24 to 61) were divided into the following 2 groups on the basis of apparent bad breath by the olfactory judgement; bad breath group (group B, n = 13), and no bad breath group (group N, n = 11). A gas tight syringe was employed to withdraw 5 ml mouth air samples, which were injected directly into the gas chromatograph. Volatile sulphur compounds produced in mouth air were analyzed by gas chromatograph to determine volumes of CH3SH. Subgingival plaque samples were taken with sterilized paper points from the deepest site of probing depth in each subjects. The samples were examined by means of dark field microscopy and 100 bacteria in randomly selected fields were classified on a percentage basis into one of the following morphological categories: (1) spirochetes, (2) motile rods, (3) filaments, (4) fusiforms, (5) straight rods, and (6) coccoid cells. Total cell counts per 1 ml were calculated from bacterial counts of each categories. Comparison of 2 independent means from each groups were carried out by Wilcoxon's rank sum test for nonparametric values. Correlations of bacterial data with CH3SH values in mouth air were determined by means of Spearman rank correlation cofficient. Results were as follows; 1. Significant differences existed in the microbial flora between the 2 groups: percentage of spirochetes and motile rods in group B were significantly higher than those in group N (p less than 0.01). Total cell counts of group B were significantly greater than group N, and there were statistically significant differences (p less than 0.01). 2. CH3SH values in mouth air had positive correlations with the percentage of spirochetes, the percentage of motile rods, and total cell counts. These results are consistent with the view that subgingival microorganisms play a certain role in the production of bad breath. Moreover, it was suggested that spirochetes and motile rods are related to the mechanism of bad breath production.