Written By Kevin Kerfoot / Reviewed By Ray Spotts
Researchers with King's College London Faculty of Dentistry, Oral & Craniofacial Sciences recently pinpointed why mice don't have replacement teeth by comparing gene expression in the dental lamina, the area that forms the teeth, of the mouse and the minipig, which has two sets of teeth.
Wnt signalling is known to be required for tooth replacement in other vertebrates and the researchers now show that Wnt activity is absent in a rudimentary form of the dental lamina (RSDL) in mice. This structure forms in the mouse but then disappears, stopping the generation of another set of teeth.
Forming additional replacement teeth
Using sophisticated genetic techniques, the researchers activated Wnt signalling in the mouse RSDL at E15.5 and E16 stages of development, revitalizing this structure, and additional teeth were formed as a consequence.
These results – published in Development - demonstrate the potential of the RSDL as a source for replacement teeth in mice, and provide an experimental system suitable for studying the mechanisms behind replacement.
"Why the potential for tooth replacement varies so much across vertebrates is an intriguing question," says Ph.D. student Elena Popa. "Our results show that, although the mouse normally does not form a second replacement set of teeth, it still has the potential to do so given the right signals."
Tooth replacement advancement
These results provide a conceptual advancement in the tooth-replacement field, as well as providing new insights into how traits are lost during mammalian evolution and how they might be restored. They report that culturing the RSDL in isolation stimulated its tooth-forming potential, suggesting that the first generation of teeth might prevent replacement teeth from developing; the previous set of teeth also influence the development of a next set.
"This is relevant to human tooth replacement, as structures similar to the RSDL have been identified next to the permanent teeth during development. In normal development of our teeth, therefore, the second set or permanent tooth may inhibit the generation of a third set of teeth," added Professor Abigail Tucker.
Regenerating Dental Tissue
Collaborative research between the Kornberg School of Dentistry and the College of Engineering uses stem cells to regrow the pulp-dentin complex that makes up the center of a tooth so that undergoing a root canal may someday be a more pleasant experience.
Associate Professor of Endodontology Maobin Yang, director of the Regenerative Health Research Laboratory at the Kornberg School of Dentistry, and Professor and Department Chair of Bioengineering Peter Lelkes’ collaborating research focuses on using dental stem cells to regenerate the pulp tissue - including blood vessels and nerves - and dentin tissue that comprises the inside of a tooth.
“These two tissues come from a similar region and have a close relationship to each other,” Yang says. “They make up the pulp-dentin complex.
“If dentin decay is not that severe, the pulp can generate new dentin to repair it - all this happens naturally. But when we see patients, most have the pulp infected, so the nerve has to be taken out. The root canal is then empty, so we currently fill up the root canal with inert treatment.”
In an effort to find a better treatment than the inert substance typically used in root canals, Yang began to research the use of stem cells in conjunction with a small scaffold to simultaneously regenerate both tissues that form the pulp-dentin complex. In generating the tissue using stem cells, there’s one major problem.
“When you put the components into the canal, they don’t have spatial control, so they don’t know where to grow the pulp and the dentin - the dentin outside and the pulp inside. So we need structure,” Yang continued.
Their findings were published in the journal Tissue Engineering.
Lelkes, a Laura H. Carnell Professor, worked with Yang to develop a bioengineered two-sided scaffolding to guide the tissue growth. “The beauty of the system is that we have shown in vitro that we can engineer a two-sided scaffold, and can guide the stem cells to differentiate into both pulp cells and dentin, producing odontoblasts that will eventually repair the root canal,” Lelkes says. “We can do this differentially with great efficacy.”
Growing full teeth is still a bit distant in the research, because the various materials that make up teeth are complex and differ in their components. Most similar research focuses on regenerating parts of the tooth and regenerating the nerve and dentin, as they are, is particularly valuable, as root canal treatment is such a common procedure.
The next step for the researchers is to test the tissue growth technique in animal models.
“I believe in the next 10 years, or even sooner, when patients come to the endodontist for a root canal treatment, we will be able to provide an alternative, equivalent or even better treatment modality, which is to regrow the nerves and the blood vessels and to grow new pulp back into your tooth, instead of using inert material,” Yang added. “With investments and with lots of research, I believe that we will get there soon.”
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With over 30 years of writing and editing experience for newspapers, magazines and corporate communications, Kevin Kerfoot writes about natural health, nutrition, skincare and oral hygiene for Trusted Health Products’ natural health blog and newsletters.
Founder Ray Spotts has a passion for all things natural and has made a life study of nature as it relates to health and well-being. Ray became a forerunner bringing products to market that are extraordinarily effective and free from potentially harmful chemicals and additives. For this reason Ray formed Trusted Health Products, a company you can trust for clean, effective, and healthy products. Ray is an organic gardener, likes fishing, hiking, and teaching and mentoring people to start new businesses. You can get his book for free, “How To Succeed In Business Based On God’s Word,” at www.rayspotts.com.