Will growing new teeth come sooner than we think?

Dr. Paul Sharpe has earned an international reputation for his research into using stem cells to grow new teeth. He has demonstrated in animal studies that a natural tooth, together with its associated bone, root, and nerves, will grow from a tooth “bud” or “primordium” of stem cells placed into an incision in the gum. He will be among the invited speakers this week at the First International Conference on Dental and Craniofacial Stem Cells in New York City. There he will discuss his most recent research into the niches in tooth pulp where stem cells reside.(1) “In the future we envision,” explains Dr. Sharpe, “a patient who loses a tooth and wants a replacement will be able to choose between current methods and a biological-based implant—a new natural tooth—derived from the patient’s own dental stem cells.” Notwithstanding steady progress in the prevention and treatment of dental disease, the toothless and those lacking some or most of their teeth still make up a huge population. According to dental-health surveys, about 70 percent of adults in the United States have lost at least one tooth; about 58 percent of those aged 50 and older have fewer than the 21 teeth considered ‘functional dentition’; and about 18 percent aged 65 or older have no natural teeth at all.(2) To be sure, it will be some years before there is no one removing a mouthful of dentures at night to place them in a cup on the bedside table. Yet the work of Dr. Sharpe and other investigators has brought another option into view. In 2004, for example, he and his colleagues reported in the Journal of Dental Research (JDR) that they had used stem cells to grow teeth in mice.(3) The stem cells used in that work were not human dental stem cells but rather mouse embryonic stem cells and bone-marrow-derived stem cells. Even so, as the editor of JDR said in a commentary, “Clearly, the future for regenerative and tissue-engineering application to dentistry is one with immense potential, capable of bringing quantum advances in treatment for our patients.”(4) Later Dr. Sharpe and his team received the William J. Gies Award for best paper published in JDR that year in the category of biomaterials and bioengineering. Dr. Sharpe has noted the particular advantages that human dental stem cells offer in taking this research further: Unlike human embryonic stem cells, they are plentiful and raise no ethical issues—a potential source becomes available every time a dentist or dental surgeon pulls a loose baby tooth or a molar; unlike bone-marrow stem cells, dental stem cells do not require an additional invasive procedure to obtain; and dental stem cells can be preserved for the donor’s own use, eliminating the chance of rejection if later used for the donor. Although experiments in growing new teeth remain early-stage research, other applications of dental stem cells have already been demonstrated in human studies. These cells have been successfully used to regrow jawbone and treat periodontal disease. Moreover, leading-edge research in regenerative dentistry fosters progress in regenerative medicine as well. Teeth, unlike, say, the pancreas or the heart, are readily accessible, making it relatively easy to do procedures that demonstrate general principles in organ restoration. As Dr. Sharpe once quipped, “Patients just have to come in and open their mouths.”

Footnotes: 1 Title: The rodent incisor mesenchymal stem cell niche. 2 Sources: “Oral Health Resources,” 2008, National Center for Chronic Disease Prevention and Promotion, Centers for Disease Control and Prevention (CDC), and “Oral Health, U.S., 2002,” produced by the CDC and the National Institutes of Health. These data derive from various surveys conducted in prior years. “Oral Health, U.S., 2002” defines the functional dentition of 21 as enough “to eat, speak, and socialize without active disease, discomfort, or embarrassment” without need of dentures. A full set of adult teeth numbers 32. 3 Ohazama A, Modino SA, Miletich I, Sharpe PT. Stem-cell-based tissue engineering of murine teeth. J Dent Res. 2004;83:518-522. 4 Smith AJ. Tooth tissue engineering and regeneration—a translational vision! J Dent Res. 2004;83:517.