light and stem cells repair teeth
May 29, 2014

Scientists Stimulate Dental Stem Cells With Laser

Brett Smith for - Your Universe Online

Researchers led by a team from Harvard University have successfully used a low-power laser to stimulate stem cell differentiation within the body, according to a study published on Wednesday by Science Translational Medicine.

[ Watch the Video: What Are Stem Cells? ]

The study team used a laser to stimulate dental stem cells and cause them to form dentin – the hard tissue that makes up the majority of a tooth. The study was also able to identify and describe the molecular mechanism behind the growth process.

Study author David Mooney noted that the work could eventually lead to testing of a non-invasive dental procedure.

"Our treatment modality does not introduce anything new to the body, and lasers are routinely used in medicine and dentistry, so the barriers to clinical translation are low," said Mooney, a professor of bioengineering at Harvard's School of Engineering and Applied Sciences (SEAS), in a recent statement. "It would be a substantial advance in the field if we can regenerate teeth rather than replace them."

The study team began by drilling holes in the molars of rodents. Next, the team treated the tooth pulp containing dental stem cells with a low-power laser, applied short term caps, and kept the animals secure and in good health. After around 12 weeks, observations confirmed that the treatment regimen induced improved dentin development.

"It was definitely my first time doing rodent dentistry," said study author Dr. Praveen Arany, a clinical investigator at the National Institutes of Health. “The dentin was strikingly similar in composition to normal dentin, but did have slightly different morphological organization.”

“Moreover, the typical reparative dentin bridge seen in human teeth was not as readily apparent in the minute rodent teeth, owing to the technical challenges with the procedure,” he added.

Arany told BBC News reporter James Gallagher that the procedure could potentially replace the dreaded root canal procedure in some cases.

"The laser tool and the mechanism we have outlined would ideally be used in pulp capping that would prevent root canal treatment and hopefully preserve the tooth without the need for it to be eventually extracted,” he said. "But once you reach the pulp and the pulp is necrotic, the cells you have to work with are no longer there so this would not work in those cases.”

The study team also conducted a series of culture-based tests to discover the specific molecular system behind the regenerative effects of the laser procedure. They found that a common regulatory cell protein called transforming growth factor beta-1 (TGF-ß1) helped to trigger the dental stem cells’ growth. TGF-ß1 is prevalent in a dormant form until triggered by any one of several molecules.

In stimulation process, the laser first activated reactive oxygen species (ROS), chemically dynamic molecules including oxygen that have a crucial role in cellular operations. The ROS triggered the dormant TGF-ß1complex which then separated the stem cells into dentin.

The study team said the discovery of this mechanism confirms anecdotal evidence surrounding the effectiveness of low-level light therapy (LLLT), also known as Photobiomodulation (PBM).

"We are also excited about expanding these observations to other regenerative applications with other types of stem cells," Arany said.

Image Caption: These tooth models show the relative size comparison of a human tooth versus a rat tooth -- to give an idea of the technical challenges involved with performing dentistry on such a small scale. NOTE: The small "rat tooth" is not an actual rat tooth but rather a resized human tooth. Credit: James Weaver, Harvard's Wyss Institute