Anti-bacterial effect of citric acid treatment of periodontally diseased root surfaces in vitro.

This investigation examined whether citric acid may exert an anti-bacterial effect against plaque deposits on root surfaces in vitro. Aerobic and anaerobic blood-agar plate cultures were prepared from plaque samples obtained from the proximal root surfaces of 20 periodontally diseased human teeth following extraction. Ten teeth were exposed to saturated citric acid (pH 1) for 3 min, followed by rinsing in sterile 0.85% saline and plaque samples were then obtained immediately adjacent to those sites sampled initially. Controls consisted of using sterile water instead of citric acid on a further five teeth. The numbers of colonies present on pre- and post-treatment culture plates were counted at 24 h. The results indicated that citric acid application reduced, in all instances, the numbers of colonies grown from post-exposure plaque samples as compared to pre-exposure samples. No colonies were detected in 55% of aerobic and 30% of anaerobic cultures of acid-treated root surface samples. For aerobic cultures, citric acid exposure reduced the number of colonies grown from greater than 10(4) to less than 100 in 95% of the root surfaces sampled, while for anaerobic cultures, reduction from greater than 10(4) to less than 100 was found in 80% of surfaces sampled. The findings indicate that citric acid exerts anti-bacterial activity against microbial plaque deposits present on periodontally diseased root surfaces in vitro.