Correlation between bacterial counts in saliva and subgingival plaque

The aim of this study was to examine the correlation between the number and type of bacteria from periodontal pockets more than 4 mm deep and saliva in 26 patients. Periodontal pocket samples were taken with paper points and transferred to 0.1 ml of enriched thioglicollate broth. Saliva samples were collected simultaneously in aseptic flasks. Both samples were processed within the first hour. They were inoculated in Schaedler agar plus 5 micrograms/ml vitamin K and 5% blood, TSBV agar and MGB agar to perform colony counts and identification. Spirochete counts per microscopic field were obtained by direct light microscopy of Gram-stained preparations. The results show a fair to good correlation between both samples for anaerobic, pigmented gram-negative rods, anaerobic non-pigmented gram-negative rods, spirochetes, facultative gram-negative rods other than Actinobacillus actinomycetemcomitans, anaerobic, gram-positive cocci and anaerobic gram-positive rods (Spearman correlation coefficient 0.51 to 0.96). The correlation coefficient values for A.a., facultative gram-positive rods, facultative gram-positive cocci and facultative gram-negative cocci were lower than 0.21. There were no significant differences between the counts in both samples for all the bacterial groups (Student's t test, p > 0.1). We may conclude that, under the experimental conditions of the present study, saliva samples and periodontal pocket samples are equally useful to detect subgingival organisms associated with periodontal disease in the oral cavity. Saliva samples were useful to evaluate risk and periodontal therapy in individual patients or groups.