This study investigated the effect of a surface active compound, delmopinol, on plaque formation and established plaque in vitro, on the bacterial acid production from glucose and on the total viable bacterial counts in saliva. The antimicrobial effect was compared with that of chlorhexidine. The plaque-inhibiting effect was evaluated in an artificial mouth system, and the effect on bacterial acid production was registered as a decrease of pH in bacterial suspensions with various concentrations of delmopinol. It was shown that delmopinol is able to prevent plaque formation, to dissolve established plaque in vitro, and that it has 5-125 times higher minimum inhibitory concentrations than chlorhexidine. Saliva samples collected 1 min after rinsing with delmopinol showed on differences in the total number of bacteria in saliva as compared with controls. It was also shown that the bacterial acid production from glucose was reduced successively with increasing concentrations of delmopinol. The results indicate that delmopinol might be as effective as chlorhexidine against plaque formation and that delmopinol is capable of penetrating established plaque, thus promoting a more effective mechanical cleansing.

Delmopinol is a new surface active anti-plaque agent that has demonstrated a low antimicrobial effect in vitro. By use of a vitality staining technique, the antimicrobial effect on bacteria in plaque samples was tested after rinsing with delmopinol or chlorhexidine. 6 healthy male subjects volunteered to rinse for 4 days using a double-blind cross-over study design with a wash-out period between the rinsing regimens. No oral hygiene measures were allowed during the test periods and each test period started with a professional tooth cleaning procedure 2 days before the start of rinsing to allow for plaque formation. Rinsing was performed with 0.2% delmopinol hydrochloride or 0.2% chlorhexidine digluconate 2 x a day. Small samples of plaque were collected from the buccal surfaces of premolars and 1st molars before the first rinse on day 1 and then before and 1, 2, 4, 7, and 24 h after the last rinse on the 4th day. The plaque samples were immediately stained with propidium iodide and fluorescein diacetate to visualize dead and vital microorganisms respectively. The vitality of the microflora was evaluated using a fluorescence microscope. The baseline vitality values were 91% for chlorhexidine and 86% for delmopinol. At day 4, the plaque vitality for chlorhexidine was approximately 40% up to 4 h and 50% at 7 h and 60% at 24 h after the last rinse. Corresponding values for plaque vitality after delmopinol rinsing were between 70 and 80% on all sampling occasions.(ABSTRACT TRUNCATED AT 250 WORDS)

Delmopinol is a low molecular weight surface-active compound that has been shown to be effective against dental plaque both in vitro and in vivo and against gingivitis in vivo. To study the mode of action of delmopinol, the influence of the compound on the stability of bacterial suspensions, both with and without saliva, and on the zeta-potentials of oral streptococci was studied. The results showed that delmopinol reduced the magnitude of the zeta-potentials, but, in contrast, the colloidal stability of the bacterial suspensions without saliva was increased. The explanation of these observations could be that non-DLVO interaction components, such as repulsive hydration/steric forces, have come into effect at very close distances between two approaching bacterial cells. To judge from the present results, it is possible that delmopinol forms films on bacterial cells in a plaque, thereby facilitating mechanical removal.