London: Medical research teams in the US and Europe are heading towards a technique that can grow adult teeth. Growing teeth would be a more natural and cheaper alternative to dentures, dental implants and bridges

In London researcher Paul Sharpe of Kings College, is seeking funding of $5.2 million to begin testing people within three years. The teeth would be “completely normal and identical in every way to existing teeth.”

He plans to use stem cells grown in a lab which are then reimplanted at the site of the missing tooth. It would take about two months to grow into a full tooth. It is estimated that the technique is ten years away from fruition.

While in Chicago, Tom Diekwisch of the University of Illinois is studying tooth regenration in animals.

Different teams are using different approaches. But the techniques generally involve directing immature stem cells to develop into tooth tissue.

At the US Harvard School of Dental Medicine another team headed by Pamela Yelick has used rat stem cells to grow well-formed crowns, with layers of enamel, dentin and pulp. Her team also has grown pig tooth crowns.

It is likely that tooth repairs will precede whole teeth. Stem cells could, for example be used to repair cracked teeth rather than use synthetic materials. It also might be possible to regenerate pulp inside the tooth, thereby eliminating the need for root canals.

The key to growing or regenerating teeth is coaxing stem cells to do the job. A stem cell is an unspecialized cell that can develop into a specialized cell.

Stem cell research is under way on many fronts. For example, researchers hope to coax stem cells to produce insulin for diabetics, regenerate heart muscle for cardiac patients or repair spinal cord injuries for paraplegics.

Some researchers are obtaining stem cells from human embryos, which opponents consider unethical because embryos are destroyed in the process. But the stem cells that would be used to grow or repair teeth would not come from embryos. They instead could be obtained from such sources as the patient’s mouth, jaw, blood or existing teeth. Some researchers prefer to use the term progenitor cells.

Although improved dental care is enabling more people to keep their teeth, tooth loss remains a huge problem. By age 44, nearly seven in 10 American adults have lost at least one tooth to decay or gum disease. And about one in four elderly adults have lost all of their teeth.

It costs anywhere from $1,500 to $3,000 to replace a lost tooth with an implant or a bridge.