Relationship of the subgingival microbiota to a chairside test for aspartate aminotransferase in gingival crevicular fluid.

BACKGROUND

The aim of the present study was to evaluate the association between the occurrence of certain specific periodontal pathogens and aspartate aminotransferase (AST) levels in gingival crevicular fluid (GCF).

METHODS

Thirty systemically healthy subjects with moderate to advanced periodontitis were selected. Within each subject, the AST contents of GCF from sites with probing depth between 5 mm and 7 mm were measured using a chairside colorimetric test. AST-positive site refers to one that had an AST level > or = 800 microIU. Subgingival plaque samples from one AST-positive and one negative site were collected for microbiological examination. One site with probing depth < or = 3 mm and no gingival inflammation was selected as a healthy control. Clinical parameters of the chosen sites, including the plaque index and gingival index scores, probing depth, and clinical attachment level were measured. Culture and immunofluorescence (IF) were used for detecting common periodontal pathogens, including Actinobacillus actinomycetemcomitans, Peptostreptococcus micros, Campylobacter rectus, Eikenella corrodens, Fusobacterium nucleatum, Capnocytophaga species, Prevotella intermedia, Prevotella melaninogenica, and Porphyromonas gingivalis. Logistic regression was used to analyze the correlation between the AST test and certain specific pathogens.

RESULTS

The GCF scores and total cultivable bacterial counts were higher in AST-positive sites than either AST-negative or healthy sites. The prevalence and proportions of specific periodontal pathogens such as C rectus, E. corrodens, F. nucleatum, Capnocytophaga species, P. intermedia, and P. gingivalis were significantly higher in positive than in negative sites. In analyzing the correlation of the proportion of 6 pathogens with the AST test by logistic regression, only P. gingivalis showed a significant positive correlation. The odds ratio of having a high proportion of P. gingivalis in the presence of a positive AST test was 1.21.

CONCLUSIONS

The present study showed that at AST-positive sites, there is a higher prevalence and higher proportion of certain periodontal pathogens. Although only the correlation of P. gingivalis and AST values was statistically significant, the results imply that certain periodontal pathogens may be associated with elevation of AST levels in GCF.