A team at King’s College London is currently testing the ability of a treatment tested for Alzheimer’s, called Tideglusib, to help regrow tooth material by stimulating stem cells; this technique could one day eliminate the need for man-made fillings.

A new experimental dental treatment could one day make the need for fillings obsolete.
According to a news release by King's College London, researchers there have found “a new method of stimulating the renewal of living stem cells in tooth pulp using an Alzheimer’s drug.” 
Typically, when patients have a cavity, the holes are filled with cement or fillings; however, over time, gaps can lead to infection or eventually extraction. 
So the team decided to test a therapy including Tideglusib, which has previously been used in clinical trials to treat Alzheimer’s disease.
The Guardian notes that "previous work by the team has shown that the drug stimulates stem cells in the centre of the tooth, triggering them to develop into odontoblasts (specialised tooth cells) and boosting the production of dentine, allowing larger defects to be reverse."
According to the press release, "Using biodegradable collagen sponges to deliver the treatment, the team applied low doses of [Tideglusib] to the tooth. They found that the sponge degraded over time and that new dentine replaced it, leading to complete, natural repair."
While the method was successful, its efficacy in humans is still questionable; researchers have already embarked on the next step in the testing process which is to try it on larger rat teeth.