What does the study say? The study explains how scientists have been able to trigger odontoblasts with a low power laser. What are odontoblasts? Odontoblasts are specialized cells in teeth that grow dentin, the inner portion of your tooth.
So, in a sense, it is true that you can regrow tooth structure with a laser. But this doesn't mean that fillings and root canals are a thing of the past or that this is anything new. This isn't a groundbreaking study because we have other materials on the market already that can trigger those odontoblasts to grow dentin. The process is called pulp capping and is used when decay (caries lesion) extends deep into the tooth. If the decay is near the pulp, but not invading the pulp, we can lay down this material that triggers those odontoblasts and causes them to grow a protective layer of dentin called tertiary dentin, that will protect the pulp from dying as a result of the deep decay.
Here's the problem with the conclusion of the article: once dentin is decayed, the only cure for it is to remove it. Just like rust on a car, you can't magically disinfect the decayed dentin. Also, once the decayed dentin is removed the remaining odontoblasts in the tooth can't regrow sufficient amount of dentin to fill the void, and they can't regrow fast enough to protect the pulp. If you have a deep cavity, you will still need a filling.
If the decay has by chance extended all the way to the pulp, you then need to remove the pulp as well by performing a root canal. So root canals and fillings are still going to be needed to fix teeth that have had deep cavities.
The best medicine though is prevention. It's better to brush and floss regularly and have regular professional cleanings so that you won't need fillings or root canals.
