The growing visibility of charcoal and charcoal-based dentifrices, including many that are offered for sale on the Internet, raises questions about the re-emerging practice of brushing teeth with products containing charcoal. A literature review in the Journal of the American Dental Association (JADA) by researchers at the University of Maryland School of Dentistry (UMSOD) concludes that dental practitioners are urged to educate their patients about unproven claims of oral benefit and safety when using charcoal and charcoal-based dentifrices. These include potential increased risks of developing caries with the use of these nonfluoridated or possibly charcoal-inactivated fluoride products.
The paper, "Charcoal and Charcoal-based Dentifrices, A Literature Review," was published in June online ahead of print by JADA, which does so to enable readers to access findings in dentistry without delay. The results of the literature review "showed insufficient clinical and laboratory data to substantiate the safety and efficacy claims of charcoal and charcoal-based dentifrices," said authors John K. Brooks, DDS, clinical professor in the Department of Oncology and Diagnostic Sciences; Nasir Bashirelahi, PhD, professor in the department; and Mark A. Reynolds, DDS, PhD, professor in the Department of Advanced Oral Sciences and Therapeutics.
"Recently, use of charcoal-based toothpastes has gained popularity in the marketplace. However, there is insufficient scientific evidence that these products effectively promote tooth whitening, oral detoxification, or provide any therapeutic properties (antibacterial, antifungal, or antiviral)," said the lead author, Dr. Brooks.
Furthermore, Dr. Brooks noted the review showed "unproven claims of safety," particularly in regard to the principal ingredient, charcoal, and in some products, to bentonite clay. The latter belongs to a heterogeneous group of clays with various industrial applications and has served as an ingredient in skin care products, medication, and toothpaste.
As for the use of charcoal, the first recorded use for oral hygiene is credited to Hippocrates in ancient Greece. It has since been used for cleaning teeth in many parts of the world including the United Kingdom, Italy, Cameroon, Nigeria, Tanzania, Republic of Senegal, Bangladesh, India, and Malaysia. Powdered charcoal, soot, or coal ash has been applied to teeth with fingers, chewing sticks, or cloth.
In recent times, sales of charcoal dentifrices and powders have rapidly emerged into the Internet marketplace. For the purposes of the study, the authors selected the first 50 consecutive charcoal dentifrices from Google.com and Amazon.com for ascertainment of product assortment and advertising promotions.
To conduct the literature review, the authors identified 118 potentially eligible articles published through February 2017, selecting randomized, controlled clinical trials with a follow-up duration of three months or longer. The results showed insufficient clinical and laboratory data to substantiate the safety and efficacy claims of charcoal and charcoal-based dentifrices.
"Larger-scale and well-designed studies are needed to establish conclusive evidence," the authors concluded.
Charcoal has been recognized as an abrasive mineral to the teeth and gingiva, which is the mucosal tissue of the gums. Inclusion in products raises concerns about damage to these oral structures, as well as increasing caries susceptibility due to the potential loss of enamel. Twenty-eight percent of these products claimed to be low-abrasive but laboratory test results for dentin abrasivity were provided for only one product, the study found.
"Thirty-eight percent of the products were promoted as fortifying, strengthening, or remineralizing the teeth," the authors wrote, "and yet only one of these products contained fluoride, a compound well recognized to enhance enamel mineralization."
Of three other charcoal dentifrices advertised as containing fluoride, none were promoted as providing remineralization. And for any of the four products containing fluoride, the authors raised an intriguing question: would the fluoride be rendered either chemically inert or minimally effective by the charcoal?
The American Dental Association Seal of Acceptance was not displayed with any of the 50 products.