They then shone a non-ionising, low-power laser on the exposed tooth structure and the soft tissue underneath it. This allowed the light to reach the dental stem cells deep inside the pulp of the tooth.
Twelve weeks after a single 5-minute treatment, new dentin had formed in the cavity. Similar dentin production was seen in mice and in cultured human dental stem cells.
The author writes as if this new process will eliminate fillings, but if you read the article that is not the case at all. The experiment showed dentin growth but not enamel. Never the less it is pretty amazing!