Goodbye root canals? Researchers use lasers to regrow parts of teeth

For the millions of Americans who suffer cavities each year, the ominous threat of a root canal may soon be a worry of the past.

Now, researchers from Harvard University claim they have discovered a novel way of regrowing parts of people’s teeth using an unlikely tool: Lasers.

In a new study published in the journal Science Translational Medicine, lead researcher Praveen Arany and colleagues detailed how they used focused laser light therapy on rats to stimulate the growth of lost dentin, the calcified tissue that comprises teeth.  They noted that if the therapy proves effective in humans, it could potentially eliminate the need for crowns, fillings and other complex dental operations in the future.

The procedure’s success all revolves around a native protein called transforming growth factor beta, or TGF-beta.  During preliminary tests of dentin tissues, the researchers discovered that this growth factor changed very drastically when introduced to a focused beam of light.  Further analysis revealed that when hit with light, TGF-beta actually stimulated the stem cells already present in dentin.

“Once [TGF-beta] is activated by the laser, it can bind to stem cells resident in the tissue, and then it induces those stem cells to differentiate so they can proliferate and reform dentin,” David Mooney, the Pinkas Family Professor of Bioengineering at Harvard University, told FoxNews.com.

Numerous studies have focused on ways to manipulate stem cells in order to spur tissue regeneration, but most of these techniques have revolved around reintroducing altered stem cells into the patient or directing stem cell populations externally through added growth factors.  With this form of laser therapy, the only external factor that is being introduced is light, which activates TGF-beta that’s already in the body.

According to Mooney, it’s not the laser’s heat that stimulates TGF-beta but the energy of its photons.  When light is focused on dentin, the photons get absorbed into the tissue and activate molecules called reactive oxygen species (ROS), which naturally occur in the body.  These ROS then stimulate TGF-beta, which spurs the chain reaction ultimately leading to dentin reformation.

However, Mooney noted that the power of the laser must be at a specific level of intensity and cannot produce any heat in order to be effective.

“It’s kind of like Goldilocks, too little won’t do enough and too much will become destructive,” Mooney said. “It has to be just right.”

To test their light therapy’s effectiveness, the researchers created a group of rats with tooth defects, by using a drill to remove pieces of their dentin.  They then shined a laser on their exposed tooth structures and soft tissues underneath it.  Sure enough, after 12 weeks, the team observed that new dentin had formed in the rats’ teeth.

Given their trial’s success, Arany and his team hope to test this type of dentin regeneration in human clinical trials, which could potentially alter modern dentistry.  Currently, if a patient has a chipped or decayed tooth, dentists will use synthetic materials to fix the problem or perform a root canal if the tooth has become too infected. Yet, Arany noted that laser therapy could erase the need for these uncomfortable dental procedures, simply by regrowing the part of the tooth that is missing.

He also noted that focused laser therapy could be used to grow more protective dentin in teeth that have grown sensitive due to gum recession.

“As we grow older our gums recede, exposing our teeth root,” Arany, assistant clinical investigator for the National Institutes of Health, told FoxNews.com. “The root is covered by cementum, which is not as protective as enamel, so you get dentin sensitivity….What we hope is in tooth sensitivity, [laser therapy] is able to generate an intrinsic protective barrier on the inside of the tooth.”

Expanding beyond the world of dentistry, the researchers note that TGF-beta is found in other bodily tissues, such as skin and bone, and that laser therapy could potentially help regrow tissues in those systems, as well.  Also, since TGF-beta is known to control tissue inflammation, the growth factor could perhaps be stimulated to control certain inflammatory diseases.

But for now, the team is focused on TGF-beta in relation to teeth, and they are hopeful that their laser therapy could be used in a clinical setting relatively soon.

“This laser is already a big part of the clinic, since so many of the clinicians use it for other purposes,” Arany said.  “So the barrier to clinical trial translation is relatively low.”