Chlorhexidine and thymol in a varnish can prevent root caries, but chlorhexidine rinse is probably useless against caries of all kinds.
This finding is perhaps the biggest surprise in a comprehensive review of nonfluoride caries-preventive agents performed by a panel of the American Dental Association (ADA) and published in summary in the September issue of the Journal of the American Dental Association, with a more detailed report available on the organization’s Center for Evidence-Based Dentistry Web site.
“We are moving toward management of caries as a chronic condition, rather than putting in a filling and watching until it breaks,” Michael Rethman, DDS, lead author of the review and vice president for scientific research at the ADA foundation, told Medscape Medical News.
Most dentists agree that proper hygiene, diet, and use of fluoride can help prevent caries, but there is little consensus on what else works.
For example, 7.7% of children and 17.3% of adults were prescribed chlorhexidine rinse, according to a survey cited in the review. About a third of adults and children were told to use xylitol gum.
The confusion is not surprising, as there has not been enough research performed on most such substances, the ADA panel found. Dr. Rethman cautioned that the panel was only reporting on the scientific data and said individual clinicians should also bring their experience to decisions about these substances. In addition, in an accompanying statement, the ADA pointed out that the findings only summarized the scientific evidence and should not be interpreted as the standard of care.
Stuart Fischman, DMD, professor emeritus of oral diagnostic sciences at the State University of New York at Buffalo, said the panel had taken the right approach in emphasizing that no substances have been as well proven as fluoride for preventing caries. “I think they have taken the right tone,” he told Medscape Medical News.
Still, the recommendations could prove disappointing to practitioners casting about for a reliable tool in cases of caries that resist fluoride and other well-established treatments. For example, many companies have recently marketed products containing calcium phosphate as a means of remineralizing dental lesions. Perhaps the most familiar in the United States is MI Paste (GC America).
The panel found a handful of studies suggesting promise for calcium phosphate in various forms, but it could not pool the results because the substances were too different from each other. It concluded that the evidence was “insufficient” to recommend either for or against them.
In contrast, the panel found several adequate studies on 0.05% to 0.12% chlorhexidine rinses for coronal caries. It pooled the results from 4 randomized controlled trials and found that the difference between the number of decayed, missing, or filled surfaces in patients who used chlorhexidine and those who used a placebo was not statistically significant. The panel obtained similar findings for root caries.
Dr. Fischman said he was not surprised by the results. “The role in caries has never really been accepted by professionals,” he said. However, he added that this review said nothing about the potency of chlorhexidine varnishes for periodontal disease.
In addition, for a varnish combining chlorhexidine with thymol, the panel found 3 randomized controlled trials showing efficacy against root caries, and concluded that this approach works.
In contrast, studies on chlorhexidine and thymol varnish for coronal caries did not show a statistically significant advantage, so the panel did not support this treatment.
There was not enough evidence to make conclusions about chlorhexidine varnish without thymol for adults, and 10% to 40% chlorhexidine varnish without thymol did not seem to reduce the incidence or caries in children.
Evidence for chlorhexidine gels was also lacking.
Among the panel’s other findings were that:
Xylitol chewing gum marginally reduces the incidence of caries in children, and children with caries experience could also benefit from xylitol lozenges or hard candy, but there is not enough evidence to recommend xylitol syrup for children younger than 2 years or to recommend xylitol dentifrice.
There is not enough evidence for using triclosan, iodine, or sialogues against caries.
There is not enough evidence that xylitol, chlorhexidine, or calcium products given to mothers can reduce caries in children.
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