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"The results of this study give tobacco chewers yet one more reason to quit," said lead author Scott Tomar, D.M.D., Dr.P.H., National Center for Chronic Disease Prevention and Health Promotion, CDC. "We already know that chewing tobacco use is a risk factor for gingival (gum) recession and oral cancer," he said. "The damage that it can do to teeth is another item we can add to the list of health consequences."
The CDC-NIH study of dental caries and chewing tobacco use in the United States is the first large-scale, detailed analysis of the relationship between dental decay and the leafy form of tobacco. The study results appear in the November issue of the Journal of the American Dental Association.
The researchers analyzed dental caries and tobacco use data from more than 14,000 adults aged 18 and over. The data were collected by the National Center for Health Statistics between 1988-1994 as part of the Third National Health and Nutrition Examination Survey.
The researchers distinguished between the two types of spit tobacco, also called smokeless tobacco, and other types of tobacco such as cigarettes, pipes, and cigars. Spit tobacco comes in two forms, chew and snuff. Chewing tobacco is a bulky, leafy form of tobacco that is packaged as loose leaf, plugs, or twists, and snuff is a finely ground or shredded tobacco.
The survey data revealed that 6 percent of men aged 18 and older use some form of spit tobacco, a figure that is consistent with other recent studies on tobacco use. (The researchers limited their data analysis to men since the vast majority of spit tobacco users are men.) Of the men who use spit tobacco, 59 percent use the chewing tobacco form. Almost half of those who use chewing tobacco also use one or more other types of tobacco.
The study showed that men who use chewing tobacco exclusively were four times more likely than those who had never used tobacco to have one or more decayed or filled root surface. Men who currently use only chewing tobacco also were more likely than former tobacco users or those who currently used only snuff to have root caries. On average, the men who used chewing tobacco exclusively had 3.84 decayed or filled root surfaces (out of 112 possible surfaces), more than any other tobacco-use group and those who had never used tobacco.
The researchers also found a dose-dependent relationship between chewing tobacco use and the likelihood of having root caries. The more packages of chew a man used each week, the more likely he was to have a decayed or filled root surface. Additionally, the more years a man had used chewing tobacco, the more likely he was to have a decayed or filled root surface.
The researchers speculate that the high sugar content in chewing tobacco is one reason the product is associated with an increased risk of dental caries on tooth roots and crowns. Additionally, the way chewing tobacco is used might also help promote tooth decay, the scientists say. A typical user holds a wad of chew in his cheek for 30 minutes at a time and uses the product in this manner throughout the day, exposing the teeth to the tobacco for several hours. Moreover, both chew and snuff can contribute to gingival (gum) recession and therefore make tooth roots more vulnerable to decay.
"This study shouldn't give chewers the idea they can switch to snuff," said study author Deborah Winn, Ph.D., National Institute of Dental and Craniofacial Research, NIH. "Spit tobacco users should be aware that both chew and snuff are addictive and can cause oral disease." According to Dr. Winn, earlier studies have linked spit tobacco in various forms to gingival recession, oral lesions, and oral cancer.
The Centers for Disease Control and Prevention in Atlanta, Ga., and the National Institutes of Health in Bethesda, Md., are part of the Federal government's Department of Health and Human Services.