In the last few years, researchers have made significant strides not only in understanding how bacteria settle into their particular niches but also in developing methods to prevent certain harmful strains from doing so. At the University of Alabama School of Dentistry, Page Caufield, a professor of oral biology, found that humans are colonized by S. mutans-the cavity-causing bacteria-during a “window of infectivity,” around two years of age. At that time, S. mutans is usually passed from the primary caregivers probably as they spew saliva droplets while talking into the face of a child whose teeth are emerging. “The window opens and closes,” says Caufield. “If children aren’t infected by S. mutans then, another bacteria species moves in and uses that niche. People don’t exchange S. mutans as adults.”In an attempt to prevent the transmission of S. mutans to children, Caufield and his team will soon begin clinical trials on 250 mothers who carry particularly harmful strains of the bacteria. Their teeth will be treated with Chlorzoin, an antimicrobial dental sealant, that can effectively block colonization of S. mutans for up to six months, during their children’s window of infectivity. The researchers say that the procedure will have no effect on the other bacteria-beneficial or otherwise-that began colonizing the babies’ mouths from the moment they were born. Thus they hope that the trials will prove this a safe means of allowing 250 children to live a life free of the S. mutans strains that have plagued their mothers.
Chlorzoin is also undergoing clinical trials in several other countries. The largest clinical trial involves more than 1,300 school-age children in Dundee, Scotland. The children, who have been identified as at high-risk for S. mutans, are having their teeth painted with the sealant several times over three years. Researchers hope that it will reduce S. mutans populations to a level so low that cavities will be prevented.
In the meantime, Chlorzoin, which was developed by researchers at the University of Toronto and approved as a prescription drug in Canada in 1993, is already being sold by Oralife, a Toronto-based company that has teamed up with a Canadian dental insurance company to train dentists to use Chlorzoin. The dentists will include Chlorzoin as part of a decay-prevention program in children and adults who have especially virulent strains of S. mutans or conditions such as dry mouth that exacerbate tooth decay. If the program proves successful, Ross Perry, president of Oralife, anticipates that dental sealants will soon be used in the United States.
According to Perry, approximately 10 percent of North Americans are at high risk for tooth decay, while another 10 to 15 percent are at medium risk. The amount spent on restorative dentistry by these two groups accounts for 60 percent of the total dollars spent on dentistry. “By doing this treatment over two years, S. mutans can be reduced, and adults can move down a notch in their risk factor,” he says. “Before this program, insurance companies never paid for prevention. They always paid after a person was infected.”