Chlorhexidine is a bis-biguanide formula with cationic properties. The molecule is symmetric with two 4, chlorophenyl rings and two biguanide groups linked by a hexamethylene chain. As a disinfectant called Hibitane, the drug was introduced more than 20 years ago.
Chlorhexidine has an affinity for bacteria probably due to the positively charged chlorhexidine molecule and the negatively charged groups on the bacterial cell wall. Binding increases permeability of the cell wall and permits the agent to penetrate into the cytoplasm and cause death.
Flotra et al. (1972) reported substantial reduction in the amount of plaque and gingivitis in 50 soldiers who used chlorhexidine and tooth brushing for 50 months. Flora stated, however, that established periodontitis was not influenced i.e. subgingival plaque was unaffected. A number of reports have shown the affinity of chlorhexidine for proteins, bacteria and extracellular polysaccharides of bacterial origin. During a mouthrinse, chlorhexidine molecules immediately bind to acidic macromolecules on oral surfaces and are retained there. From these areas of retention, the drug is gradually released and the concentration of chlorhexidine in the mouth is kept on a level sufficient to create a bacteriostatic environment for a prolonged period of time.
Chlorhexidine rinses kill only about 80% of the bacteria in the saliva. Moreover, two daily mouth rinses are capable of keeping the relatively low level of variable microorganisms in the saliva fairly constant. When chlorhexidine usage is terminated, the number of bacteria returns to pre-experimental values within 48 hours. Chlorhexidine has been reported to be effective against Candida albicans in vitro and in vivo (denture stomatitis). There is no evidence that chlorhexidine is permanently retained in the body. The drug may penetrate the oral mucosa, but the amounts are probably very small. Some of the more serious side effects reported are: interference of taste sensation, staining, mucosal desquamations and possible interference with anti-viral mechanisms. Side effects increase with increasing use of the drug.
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