Tooth repair with the natural materials of the teeth will allow rebuilding teeth damaged by decay.
"What we're hoping to have happen is to catch [decaying teeth] early and remineralize them," said Sally Marshall, a professor at the University of California at San Francisco. Marshall gave a talk last week at the spring meeting of the Materials Research Society on rebuilding the inner portions of teeth.
While regrowing your uncle's toothless grin from scratch is still a decade away, the ability to use some of the body's own building materials for oral repair would be a boon to dentists, who have been fixing cavities with metal fillings since the 1840s.
Marshall thinks she's just a few years away from knowing how to restore dentin. Give the ability to restore dentin and enamel conventional fillings will become obsolete.
Some skeptics of the prospects for radical life extension see body rejuvenation as a very distant prospect. Yet a method to restore dentin and enamel is a form of rejuvenation. Granted this rejuvenation is only done to teeth. But teeth are a part of the body. So rejuvenation therapy to one part of the body is just a few years away.
We need the ability to grow replacement dental enamel as our teeth wear with age.
Dental enamel is the hardest tissue produced by the body. It cannot regenerate itself, because it is formed by a layer of cells that is lost by the time the tooth appears in the mouth. The enamel spends the remainder of its lifetime vulnerable to wear, damage, and decay. For this reason, it is exciting to consider the prospect of artificially growing enamel, or even whole teeth, using culturing and transplantation techniques.
Consider how people wear braces to straighten teeth. Also, people get replacement crowns put on teeth. But instead of replacement crowns imagine braces that hold a covering over teeth and that inside the covering cells get inserted that can grow enamel. You'd wear enamel growing incubators over your teeth to build them back up after years of wear and tear. The existing teeth would get recapped periodically using the same types of cells that created the teeth in the first place.
Some Japanese scientists have made progress on methods to grow enamel-forming cells in larger numbers.
In the emergent field of tooth-tissue engineering, several groups have developed their own approaches. Although there has been some success in producing enamel-like and tooth-like tissues, problems remain to be solved before the technology comes close to being tested in humans. One of the issues has been how to produce, in culture, sufficient numbers of enamel-forming cells.
Today, during the 85thth General Session of the International Association for Dental Research, a team of researchers from the Institute of Medical Science, the University of Tokyo (Japan), reports on a new technique for culturing cells that have the capacity to produce enamel.
The scientists boosted cell growth by use of a special feeder cell layer. My guess: some day synthetic surfaces and drugs that serve in their place.
This group has recently shown that epithelial cells extracted from the developing teeth of 6-month-old pigs continue to proliferate when they are cultured on top of a special feeder layer of cells (the feeder-layer cells are known as the 3T3-J2 cell line). This crucial step boosts the number of dental epithelial cells available for enamel production. In the study being reported today, the researchers seeded the cultured dental epithelial cells onto collagen sponge scaffolds, along with cells from the middle of the tooth (dental mesenchymal cells). The scaffolds were then transferred into the abdominal cavities of rats, where conditions were favorable for the cells in the scaffolds to interact and develop. When removed after 4 weeks, the remnants of the scaffolds were found to contain enamel-like tissue. The key finding of this study was that even after the multiple divisions that occurred during propagation of the cells in culture, the dental epithelial cells retained the ability to produce enamel, as long as they were later provided with an appropriate environment.
Useful human treatments still lie years in the future. But these results provide hope for better dental repair solutions 10 to 15 years from now.
I expect the rate of increase in this research to accelerate as microfluidic devices, gene chips, nanomaterials, and other tools for working at small scales provide scientists with much faster and easier ways to manipulate and measure cells and cellular components.
Tooth root material was grown in pigs using stem cells isolated from wisdom teeth of humans.
Los Angeles, CA., Dec.20, 2006-A multi-national research team headed by USC School of Dentistry researcher Songtao Shi, DDS, PhD, has successfully regenerated tooth root and supporting periodontal ligaments to restore tooth function in an animal model. The breakthrough holds significant promise for clinical application in human patients.
The study appears December 20 in the inaugural issue of PLoS ONE.
Utilizing stem cells harvested from the extracted wisdom teeth of 18- to 20-year olds, Shi and colleagues have created sufficient root and ligament structure to support a crown restoration in their animal model. The resulting tooth restoration closely resembled the original tooth in function and strength.
Here is the abstract and the full text of the research paper.
Mesenchymal stem cell-mediated tissue regeneration is a promising approach for regenerative medicine for a wide range of applications. Here we report a new population of stem cells isolated from the root apical papilla of human teeth (SCAP, stem cells from apical papilla). Using a minipig model, we transplanted both human SCAP and periodontal ligament stem cells (PDLSCs) to generate a root/periodontal complex capable of supporting a porcelain crown, resulting in normal tooth function. This work integrates a stem cell-mediated tissue regeneration strategy, engineered materials for structure, and current dental crown technologies. This hybridized tissue engineering approach led to recovery of tooth strength and appearance.
The researchers used swine (i.e. pigs) to grow the teeth in.
To accomplish functional tooth regeneration, we used swine because of the similarities in swine and human orofacial tissue organization. Swine SCAP were loaded into a root-shaped HA/TCP block that contained an inner post channel space to allow the subsequent installation of a porcelain crown (Figure 5A). A lower incisor was extracted and the extraction socket was further cleaned with a surgical bur to remove remaining periodontal tissues (Figure 5A). The HA/TCP block containing SCAP was coated with Gelfoam (Pharmacia Canada Inc., Ontario, Canada) containing PDLSCs and inserted into the socket and sutured for 3 months (Figure 5B–E). CT examination revealed a HA/SCAP-Gelfoam/PDLSC structure growing inside the socket with mineralized root-like tissue formation and periodontal ligament space. The surface of the implanted HA/SCAP-Gelfoam/PDLSC structure was surgically re-opened at three months post-implantation, and a pre-fabricated porcelain crown resembling a minipig incisor was inserted and cemented into the pre-formed post channel inside the HA/TCP block (Figure 5F–H). After suture of the surgical opening, the porcelain crown was retained in situ and subjected to the process of tooth function for four weeks (Figure 5I, J). CT and histologic analysis confirmed that the root/periodontal structure had regenerated (Figure 5K–M). Moreover, newly formed bio-roots demonstrated a significantly improved compressive strength than that of original HA/TCP carriers after six-month implantation (Figure 5N). These findings suggest the feasibility of using a combination of autologous SCAP/PDLSCs in conjunction with artificial dental crowns for functional tooth regeneration.
We need the ability to grow replacement parts. Every step in that direction is something to be cheered. Way to go scientists!