EFFECT OF A COMBINED CHLORHEXIDINE AND NAF MOUTHRINSE - AN IN-VIVO HUMAN CARIES MODEL STUDY

Chlorhexidine (CHX) is probably the most widely used and the most pote nt chemical plaque inhibitory agent, whereas fluoride (F-) is the only truly accepted anticaries agent available at present. As they have di screte mechanisms of action, a combination effect of these agents on h uman dental caries may exist. The inhibitory effect of CHX on the form ation of, and acid production in, plaque may reduce a relatively extre me cariogenic challenge sufficiently for it to be overcome by the loca l F- concentrations achieved by brushing or rinses. The aim of this st udy was to evaluate the possible caries inhibitory effect of combining 2.2 mM CHX mouthrinses used twice daily with daily 11.9 mM NaF rinses in an in vivo human caries model using plaque-retaining bands on prem olars scheduled for extraction. Nine subjects (a total of 28 teeth) we re fitted with the bands for 4 wk. Saliva and plaque samples were coll ected before and after the study period for bacterial cultures, and th e tooth surfaces were analyzed by microradiography after careful tooth extractions. The combination of CHX and F- rinses resulted in enamel mineral loss only slightly higher than that observed in ''sound'' enam el and clearly less than with F- rinses alone. Both total plaque bacte ria and Streptococcus mutans were reduced by CHX rinses, confirming th e discrete mechanisms of action.