Oct. 3, 2014

By Medical Discovery News

For all those who cringe at the thought of going to the dentist or hearing the word cavity, there is hope. Apparently, when low-power laser light is focused onto damaged teeth, it stimulates the regrowth of dentin to correct the damage. The laser light stimulates the stem cells that are already in teeth to differentiate and repair damage from within, so that someday dentists can repair or even regrow teeth without fillings.

Teeth consist of four different tissues, three of which are harder than bone (enamel, dentin, and cementum) while one (dental pulp) is soft. Enamel, the hardest material in the body, is the outer surface of the crown of a tooth. Once enamel has completely formed it cannot be repaired, but it can remineralize. It allows teeth to withstand large amounts of stress, pressure, and temperature differences.

Dentin lies beneath enamel and forms the main portion of a tooth through numerous microscopic channels called dentin tubules. These tubules house dentinal fibers, which are the trouble-makers responsible for transmitting pain stimuli. Cementum is a thin layer of tissue surrounding the root of a tooth. Within the center of the tooth is the pulp, which provides nutrition to the tooth and mediates dentin repair. The pulp contains nerves, blood vessels, lymph vessels, connective tissue, cells that produce dentin, and stem cells.

By adding specific molecules, stem cells are coaxed into regenerating or repairing tissues. Growth factors or chemicals, among others, stimulate them to differentiate into the types of cells that make up tissues. It is a challenge to stimulate stem cells in the body without them growing uncontrollably. As a result, most approaches to stem cells involve removing them from the body, manipulating them in the lab, and then returning them. However, scientists have found that lasers promote regeneration in the heart, skin, lung, and nervous tissues. The idea was that since teeth contain stem cells, laser light might be able to stimulate them to regenerate tooth tissue and repair damaged teeth.

To test this theory, scientists drilled holes in the dentin in the teeth of rats and then shined a non-ionizing, low-power laser on the damaged area and the pulp just above the stem cells. They then capped the damaged teeth to keep the animals comfortable and healthy. With just a single five-minute treatment, new dentin formed in the damaged area in 12 weeks. The laser seems to create micro-injuries and induce highly reactive oxygen species, which indirectly activate stem cells.

They also proved that dentin production could be stimulated with lasers in cultured human dental stem cells. However, this treatment still needs some work before it could benefit people, since the stem cells that produce enamel are not present in mature teeth. And dentists would still play a role in repairing damaged teeth.

Before this experiment, results of laser treatments have generally been inconsistent, making these results that much more significant. It is the first time scientists have been able to determine how low-power laser treatment works on the molecular level. Scientists aim to advance this study into human clinical trials and even use this approach to regenerate other tissues.

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