Magazine Article

A rationale for combining chlorhexidine and fluoride for prevention of dental caries

Donnelly, Leeann, Larjava, Hannu S, Craig, Bonnie J

2000

Overview

Many preparations of CHX or fluoride are available for the prevention of gingivitis and caries (Table 2). Luoma et al.(f.16) states that \"clinical observations indicate single chemical agents used in prevention of dental diseases exert their action merely or predominately against either caries or gingivitis.\" McDermid et al.(f.18) has proposed that a combination of an anticaries and antiplaque agent may be useful and provide an additive protective effect if each agent acts at a different site. A potentially useful combination of CHX in any oral hygiene product with the addition of fluoride could be beneficial in reducing caries increments.(f.29) Since there can be an inhibitory effect on acid production and plaque formation by CHX, it may reduce the cariogenic challenge enough for fluoride to act more effectively.(f.27) There is evidence that, when used together for caries prevention, CHX and Fl provide additive benefits and together may prove valuable in the prevention of oral diseases.(f.12) A number of studies have been conducted on the effects of combining CHX and fluoride in the same vehicle and their interactions with one another (Table 2).(f.5,6,12-17,21,22) In spite of their opposite charges they have been shown to be successfully incorporated into the same vehicle without affecting their individual activity.(f.5,6,12-17,21,27,28) It appears that there is more damage to the outer structures of S. mutans by the combination of CHX and fluoride than by each agent alone.(f.20) It has been speculated that a combination of CHX and fluoride could exhibit a decrease in caries production and gingival inflammation.(f.6) There is clinical evidence that this is possible.(f.16) It has been shown that, when used together topically, sodium fluoride (NaF) and CHX in the same vehicle do not decrease the presence of free ionized fluoride or its protective action on enamel,(f.6,16) nor reduce the availability of CHX below therapeutic levels.(f.6,19) Chlorhexidine, a strong cationic compound, has the ability to form low-solubility salts with anions such as sulphate, phosphate and chloride(f.24,25) which can make it a difficult agent to incorporate into dental products without losing its antiseptic properties through interactions with other ingredients.(f.2) A fluoride used commonly in toothpaste, monofluorophosphate (MFP), was studied for its possible compatibility in formulations with CHX.(f.2) Results from this study showed that when clinically relevant concentrations of 0.2% CHX and 8.0% MFP were used, a visible precipitate formed in all samples.(f.2) This eliminated a large portion of the free CHX, leading the authors to conclude that MFP and CHX are not compatible.(f.2) In a study by Dolles et al.(f.5) it was found that when 2.0% CHX and 0.1% NaF were used together in a toothpaste, the NaF could be fully recovered, leading to the conclusion that ingredients other than the NaF were interacting and binding with the CHX. Sodium lauryl sulphate, a detergent commonly used in dentifrices, was studied for its compatibility with CHX and also found to react with and render CHX ineffective.(f.1) The time intervals of 3 to 120 minutes between use of CHX and sodium lauryl sulphate also showed that use of the two agents at a 3 minute interval did not decrease the plaque index and in fact the two agents need to be used at least 30 minutes apart or preferably greater than 120 minutes apart.(f.1) It is apparent that ingredients in toothpaste which are anionic such as sodium lauryl sulphate and MFP can have adverse affects on CHX both before and after its use. This may be due to ionic interactions(f.21) but to date no such interactions have been found with NaF and CHX.(f.12)

• Publisher: Newcom Media Inc
• Subject: Dental care / Fluorides