Denis O'Mullane, B.D.S., Ph.D., F.D.S., F.F.D., and John Clarkson, B.D.S., Ph.D.:
The extent to which practitioners make use of new methods for identifying patients at risk of dental caries and for diagnosing early carious lesions is not known. However, a worldwide increase in sales of new instruments for carrying out these tasks would seem to indicate rising interest in new techniques.
It is likely that dental practitioners choose combinations of appropriate preventive approaches for arresting or reversing early carious lesions. In the systematic review conducted by Research Triangle Institute (Bader, Shugars, Rozier, et al., 2000), it is pointed out that surprisingly few studies have been conducted on the results obtained with combined methods. For example, only four studies were found that had examined the effectiveness of combining chlorhexidine and fluoride (Spets-Happonen, Luoma, Forss, et al., 1991; Luoma, Ronnberg, 1987; Tenovuo, Hakkinen, Paunio, et al., 1992; Petersson, Magnusson, Andersson, et al., 1998) and only one study was found on the combined effect of chlorhexidine and sealants (Zikert, Emilson, Krasse, 1982).
Yet there is considerable theoretical data available to support the idea of using a combination of methods to stop or reverse early carious lesions. For example, it is now well-established that fluoride�s primary method of action is a topical one. Fluoride ions, when present at the plaque/enamel interface, reduce demineralization and promote remineralization in the presence of a cariogenic challenge (Margolis, 1993). To ensure that fluoride bestows maximum preventive benefit, it is important to maintain the ambient level of fluoride in saliva and plaque. Clearly, combining fluoride mouth rinses, fluoride toothpastes, fluoride tablets, and fluoride gels and varnishes in patients in either fluoridated or nonfluoridated communities will help maintain fluoride levels (Mainwaring, Naylor, 1978; Blinkhorn, Holloway, Davies, 1983; Murray, Rugg-Gunn, Jenkins, 1991).
Another example of a theoretical basis for a combined preventive approach involves the distribution of coronal caries by tooth surface in many communities, particularly those in which fluoride is widely used. Since the preventive effects of fluoride are concentrated on smooth surfaces, it is not surprising that data from many of these communities show that caries lesions in children and young adults tend to be confined to posterior teeth and occlusal surfaces. Hence, additional benefit is likely to be obtained by the concurrent use of fluorides and fissure sealants (Horowitz 1980). With respect to root caries, epidemiologists have traditionally attempted to distinguish between lesions which are soft and theoretically active and lesions which are hard and theoretically inactive. Thus, measures that promote the transition from soft to hardened status are considered to be beneficial (Baysan, Lynch, Ellwood, et al., 2001).
The preceding discussion forms the basis for our conference presentation. For example, studies by Ripa and colleagues (1987), Goggin and colleagues (1991), Sterritt and colleagues (1994), and Selwitz and colleagues (1995) have measured the benefits of a combined fluoride and fissure sealant approach. Ripa and colleagues found that a combination of pit and fissure sealants and weekly fluoride mouthrinsing almost completely eliminated the incidence of new carious lesions over a 2-year period. However, these studies also illustrate the difficulties in choosing an appropriate experimental design for studies of combined therapies in which the contribution of each therapy needs to be established. Those difficulties will be highlighted in our presentation, and proposals for future studies will be presented. New technologies aimed at maintaining an effective level of fluoride ions in the oral cavity, such as low-release devices, will also be considered (Toumba, Curzon, 1993).
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