Oral hygiene procedures can help to control the growth of bacteria that have adhered to the tooth surface. The main oral hygiene procedure is toothbrushing with toothpaste. Active ingredients have been added to toothpaste to try to enhance the control of adherent organisms. Other oral hygiene products, such as mouthwash, also contain components that may contribute to the control of adherent organisms, and can be used as adjuncts to toothbrushing. Antibacterial agents that may be found in oral hygiene products can be divided into the following groups (Addy, 1997; Eley, 1999):
bisguanide antiseptics phenols and essential oils
quaternary ammonium compounds natural products metal ions fluorides detergents enzymes oxygenating agents
The most effective antibacterial agent that can be used to control the growth of adherent bacteria appears to be chlorhexidine (bisguanide antiseptic). Chlorhexidine is thought to adsorb to the acquired enamel pellicle where it interacts with the bacteria that attach to the tooth surface (Addy, 1997). It acts by increasing the bacterial cell membrane permeability, which is then followed
T h e effect of phosphate-based glasses on the form ation and viability of oral bacterial biofilms April M iranda Mulligan
by coagulation of the cytoplasmic macromolecules (Eley, 1999). Chlorhexidine is available as a mouthwash. Recently, chlorhexidine has also been incorporated into toothpaste and sugar-free chewing gum (Cianco, 1992). Unfortunately, the long-term use of this antibacterial agent is limited because of the side effects associated with its use such as severe staining of the teeth (Moran etal., 1995).
Triclosan (phenol) has been reported to be approximately 65% as effective as chlorhexidine (Cianco, 1992) and is found in a number of mouthwashes and toothpastes (Eley, 1999; Moran, 1997). In some of the triclosan-containing products that are available, the active ingredient is combined with zinc citrate, which is also an antibacterial agent (Addy, 1997). The addition of zinc citrate in this case appears to increase the effectiveness of these products (Cianco, 1992). In other triclosan-containing products, triclosan is combined with a co polymer, polyvinylmethyl ether maleic acid (Addy, 1997). By itself, triclosan is not very effective at adsorbing to oral surfaces. Thus, a high level of the agent may be lost through swallowing, for example (Cianco, 1992; Marsh, 1991b). The addition of the co-polymer to products containing triclosan increases the ability of triclosan to adsorb to oral surfaces and, therefore, increases its effectiveness. No significant adverse effects of triclosan-containing products have been reported (Cianco, 1992).
Listerine is a mouthwash containing thymol, menthol, eucalyptol and methylsalicylate (essential oils) (Cianco, 1992). It acts by destroying the bacterial cell walls, inhibiting bacterial enzymes and extracting bacterial lipopolysaccharides (Mandel, 1994). Various studies {in vitro and in vivo) have shown Listerine to be effective at inhibiting plaque formation (Fine et al., 2000;
T h e effect o f phosphate-based glasses on the form ation and viability of oral bacterial biofilms April M iranda Mulligan
Charles et al., 2000; Pan et al., 1999; Riep et al., 1999). It has been shown to be slightly more effective than triclosan-containing mouthwash {in vivo) (Eley, 1999). However, adverse effects have been reported including a burning sensation and a dislike of the taste in some users (Cianco, 1991).
Cetylpyridinium chloride (quaternary ammonium compound) can be found in a wide range of mouthwashes (Addy, 1997). Cetylpyridinium chloride appears to be less effective than chlorhexidine, triclosan and essential oils (Listerine) (Cianco, 1992; Eley, 1999). Cetylpyridinium chloride can adsorb onto oral surfaces and has antibacterial activity equivalent to chlorhexidine. However, it has been suggested that cetylpyridinium chloride is rapidly desorbed from oral surfaces, perhaps explaining why it is less effective than chlorhexidine. It has also been suggested that cetylpyridinium chloride may be inactivated when it adsorbs to oral surfaces (Eley, 1999). In some users cetylpyridinium chloride- containing mouthwashes cause staining of teeth (Cianco, 1992).
Sanguinarine (natural product) can be found in mouthwashes and toothpaste (Godowski, 1989). In vivo studies have shown that sanguinarine-containing products are effective at reducing dental plaque (Harper etal., 1990; Kopczyk et al., 1991; Southard et al., 1984). However, in sanguinarine-containing products, sanguinarine is combined with zinc ions. Therefore, it can be difficult to determine whether the properties of these products are due to sanguinarine and/or zinc ions. Sanguinarine is believed to inhibit bacterial enzyme activity and reduce glycolysis (Marsh, 1992). The only side effect that has been reported with sanguinarine products is a burning sensation in some users (Cianco, 1992).
T h e effect of phosphate-based glasses on the formation and viability of oral bacterial biofiims April M iranda Mulligan
Fluoride can be found in mouthwashes, toothpaste and gels. Dental hygiene products are available that contain amine fluoride, stannous fluoride and sodium fluoride (Kagermeier-Callaway et al., 2000; Netuschil et al., 1995; Tanzer et al., 2001). Dental hygiene products containing stannous fluoride have been shown to possess plaque inhibitory properties (in vitro and in vivo), although this is likely to be due to the presence of the tin ions rather than the fluoride ions (Addy etal., 1997; Cianco, 1992; Svatun, 1978; Wade et ai., 1997). Stannous fluoride causes tooth staining, although only slight (Brecx et ai., 1993).
Sodium lauryl sulphate (detergent) can be found in mouthwashes and toothpastes (Addy et ai., 1992). It is claimed that sodium lauryl sulphate removes some dental plaque from the tooth surface and loosens the rest, making it easier for removal by toothbrushing. Studies (in vitro and in vivo) carried out to determine the effectiveness of sodium lauryl sulphate-containing products show variable results (Jenkins etal., 1991; Kozlovsky & Zubery, 1993; Landa etal., 1997).
Toothpaste containing amyloglucosidase and glucose oxidase (enzymes) is currently available (Moran et ai., 1989). These enzymes can produce a reaction that gives rise to a strong oxidising agent, which has antibacterial properties (Cianco, 1992). Toothpaste is also available containing mutanase and glucanase (Marsh, 1992). However, mutanase has been shown to have adverse effects on soft tissue (Cianco, 1992). Enzyme-containing products have been reported to be effective at reducing plaque by some authors, while others have cast doubt on their efficacy (Martin, 1992; Moran et ai., 1989).
Oxygenating agents, such as hydrogen peroxide, can be found in mouthwashes. Information regarding the effectiveness of oxygenating agents is
T h e effect of phosphate-based glasses on the form ation and viability of oral bacterial biofilms April M iranda Mulligan
limited, although the available information suggests that oxygenating agents are not particularly efficient at controlling dental plaque (Cianco, 1992; Eley, 1999).
1.5 PHOSPHATE-BASED GLASSES