Adverse Effect of Chlorhexidine and the Development of Resistant Strains, of Bacteria

The authors studied the possibility of adverse effects of chlorhexidine digluconate as applied to the oral area and the possible development of resistant Streptococcus mutans as a result of prolonged application.Different groups of experimental rats were respectively treated with 0.2% and 2.0% aquous solutions of chlorhexidine digluconate for 35 days. However, there were not observed any abnormal findings on the dental surfaces, gingivae and oral mucosa.In another series of tests with mice to which chlorhexidine digluconate was orally administerea in 5 different dosages of 12mg/Kg, 120mg/Kg, 180mg/Kg, 240mg/Kg, and 300mg/Kg, the 12mg/Kg group was found to show a normal healthy growth without abnormal findings.Five Streptococcus mutans strains were subjected to the dilution method in an effort to study the possibility of the development of resistant strains as a result of prolonged use of chlorhexidine digluconate. The result indicated that it would be difficult for resistant strains to develop.An experiment with primary school pupils, in which 3rd grade pupils were either treated with 2.0% solution or rinse of chlorhexidine digluconate in conjunction with instruction in the proper use of the toothbrush for a year, showed no abnormalcy on the dental surfaces, gingivae and oral mucosa. An application of chlorhexidine digluconate on a weekly basis proved successful in inhibiting the formation of dental plaques, and findings of this part of our studies will be given in a later report.