For years some of the world's top dental researchers have been debating the merits of calcium phosphate products without reaching a consensus. Now attorneys in New York are stepping in to thrash out the scientific evidence in court.
At issue is the claim printed in capital letters on each package of Trident Xtra Care gum: "STRENGTHENS AND REBUILDS TEETH." That's untrue, according to Jerome Noll, an attorney who filed a lawsuit on behalf of everyone in the state who bought the gum.
"We have alleged that this claim is both misleading and deceptive and therefore violates New York law," said Noll, who filed an amended complaint against Trident maker Cadbury Adams U.S.A. in Queens County Supreme Court on August 4.
A spokesperson for Kraft, the parent company of Cadbury, said the company would have no comment.
— Jerome Noll, attorney
The lawsuit could shine light on a gray area in which dental product companies interpret the research on various chemicals and devices and spin it in the most convincing way possible -- while trying to stay within the boundaries of both federal and state law.
The "strengthens" claim has attracted the ire not only of Noll's clients but also of Cadbury competitor Wrigley, whose complaints in 2008 were submitted to the Federal Trade Commission (FTC).
The FTC has yet to rule on the matter. In the meantime, an increasing number of studies have cropped up in the dental literature, along with more calcium phosphate products on store shelves.
What is it?
It's not hard to see why the minerals are getting so much attention. Most experts agree that they have huge potential in treating caries because they are the primary constituents of tooth enamel. The lesions that dentists spend most of their time fixing begin when acids dissolve calcium and phosphate from hydroxyapatite. In theory, replacing them could be as effective as pouring asphalt into a pothole.
The problem is that calcium and phosphate are not very soluble on their own. Among the researchers who have published most extensively on the topic is Eric Reynolds, Ph.D., a University of Melbourne dean of dentistry and health scientists. Noting that cheese appeared to inhibit caries, he hit upon the idea of combining calcium phosphate with casein, the key protein in cheese. The result is casein phosphopeptide amorphous calcium phosphate (CPP-ACP).
Reynolds has teamed up with various partners to market his formulation of CPP-ACP as Recaldent. In addition to Trident Xtra Care, the compound can also be found in MI Paste (also sold as Tooth Mousse).
And Recaldent is far from the only game in town. Other groups are marketing formulations of calcium phosphate, including NovaMin, SensiStat, amorphous calcium phosphate, and tricalcium phosphate. They can be found in toothpastes, rinses, gels, and sealants, as well as in prophy paste and gum.
Does it work?
The research on Recaldent as an agent for remineralization has gone farther than research on the competing products. While most of the others rely on laboratory tests with only a handful of clinical trials, Recaldent has slowed or reversed demineralization in some controlled clinical trials.
In some of them, participants wore enamel slabs while chewing sugar-free gum with or without Recaldent. Overall, as reported in Acta Odontologica Scandinavica (January 2009, Vol. 67:6, pp. 321-332), the participants whose gum had the active ingredient experienced about 8% more remineralization than those with plain gum and 14% more than those who didn't chew gum at all (p = 0.00001).
The substance also passed the test of a trial, reported in Caries Research (April 2008, Vol. 42:3, pp. 171-184), in which 2,720 patients were randomly assigned to chew a Recaldent gum or a plain sugar-free gum. Researchers used x-rays to measure the kids' caries at the beginning and after two years. They found that the Recaldent chewers' caries progressed 18% less and remineralized 53% more than the caries of the plain gum chewers (p = 0.03).
But such findings haven't convinced everyone. One reason is that participants in the enamel slab tests took off their appliances at meal time. Another is that Reynolds, the inventor, has been involved in almost all the research. Scientists normally don't consider a phenomenon proven until it has been duplicated by separate teams. Some studies by independent researchers have not found a benefit to using Recaldent.
So reviewers assessing the evidence so far have reached conflicting conclusions.
Writing in the Journal of Contemporary Dental Practice (May 2009, Vol. 1:10, pp. 1-9), reviewers at the University of Valencia sounded upbeat. "Use of CPP-ACP-based compounds offers a potential for use in the prevention of dental caries," they wrote.
But three months later, Domenick Zero, D.D.S., director of the Indiana University Oral Health Research Institute, disagreed. "The clinical benefits of CPP-ACP in paste form with and without fluoride have not yet been substantiated by credible scientific evidence," he wrote in Advances in Dental Research (August 2009, Vol. 21:1, pp. 30-34).
Gummed up
Into this muddy territory has plunged Cadbury with its claims for Trident Xtra Care. Health claims in general seem to have boosted sales of chewing gum, which are up over 10% since 2007, according to the lawsuit, which cites statistics from Mintel, a market research company. And sugar-free gum has been gaining market share over other chewing gum, reported a July 28, 2009, article in the New York Times. It quoted Cadbury's Doris Tancredi as saying "the oral care segment is clearly outpacing the overall category."
The ADA, noting that gum chewing appears to improve oral health by increasing saliva flow, has given its Seal of Acceptance to several gums, including other brands of sugar-free Trident -- but notably not Xtra Care.
"In need of a less-expensive way to keep teeth healthy, consumers have turned to retail shelves and over-the-counter products," the lawsuit states.
One such consumer was Joshua Hirsch, a Queens County resident who "bought Trident Xtra Care because he saw the representation that Trident Xtra Care would rebuild his teeth." Likewise, Soraya Balbin of New Jersey, bought the gum in New York where she works, "hoping to rebuild her teeth."
Even if Recaldent does remineralize teeth, that's not the same as rebuilding them, the lawsuit said. "A reasonable consumer would believe that the unqualified promise that a chewing gum 'rebuilds teeth' means that damage to teeth (whether the damage was caused by decay, disease, trauma, or other cause) can be reversed and repaired, not simply that portions of a weakened enamel might be remineralized."
That's probably true, said Ed Zinman, D.D.S., a San Francisco attorney who specializes in dental law. "There are certain products that remineralize teeth," he said. "Fluoride is the primary one. But it's misleading to say it rebuilds a tooth."
In addition to unspecified damages and attorneys' fees, Noll is requesting that Cadbury stop saying the gum "rebuilds teeth."
If successful, the suit could spur action against other calcium phosphate products. GC America's MI Paste website, for example, says the product "strengthens your teeth" and "helps condition, protect, and rebuild your tooth surfaces." (The company declined to comment for this article.)
And Arm & Hammer says its Whitening Booster Plus with Enamel Strengthening (which contains a different formula of ACP developed by the ADA Foundation) "helps to strengthen tooth enamel."
So will this lawsuit settle the matter once and for all? Not likely. For one thing, it doesn't challenge the remineralization claims, just the word "rebuilds." For another, making bold advertising claims is just too effective, noted Dr. Zinman.
"If they make $10 million in sales, they might settle for $1 million and still come out ahead," he said. "It's the cost of doing business."
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