EFFECTS OF CHLORHEXIDINE-FLUORIDE MOUTHRINSES ON VIABILITY, ACIDOGENIC POTENTIAL, AND GLYCOLYTIC PROFILE OF ESTABLISHED DENTAL PLAQUE

Inhibition of dental plaque acidogenicity by chlorhexidine (CHX) mouth rinses has been ascribed to a long-lasting bacteriostatic effect due t o binding of CHX to oral surface structures combined with a slow relea se rate from the binding sites. The present aims were to study the eff ects of CHX-containing mouthrinses on the viability and glycolytic act ivity of established plaque in order to assess the bactericidal versus the bacteriostatic effects. Following 2 days of plaque accumulation, three groups of 10 students rinsed with either 12.0 mM NaF, 0.55 mM CH X plus NaF, or with 2.2 mM CHX plus NaF. Plaque samples were collected before and 90 min after mouthrinsing. The pH in pooled pre- and post- rinse plaque samples was recorded before and up to 10 min after the ad dition of D-[U-C-14]glucose. Total colony-forming units in each sample were determined. High-performance liquid chromatography analyses show ed lactate to be the major extracellular glycolytic metabolite in all samples. CHX-NaF markedly reduced the colony-forming units, the pH fal l from fermentation of glucose, as well as glucose consumption and lac tate formation, whereas NaF alone exhibited no such effects. The reduc tion of glucose consumption by the CHX-NaF mouthrinses corresponded to the reduction of colony-forming units, indicating no bacteriostatic e ffect. The plaque pH in vivo was monitored in each student 90 min afte r mouthrinsing with the test solutions prior to and up to Ih after a s ucrose mouthrinse using touch microelectrodes. The CHX-NaF mouthrinses reduced the fall in pH significantly (p < 0.05) as compared with the NaF mouthrinse. The results suggested that the reduced acid formation by dental plaque following a CHX mouthrinse is due to a bactericidal e ffect rather than a long-lasting bacteriostatic action.