Amalgam vs. Composite: Filling in the Blanks

By Cedric Jackson

Throughout human history, we’ve commonly accepted that when adult teeth are lost, new ones won’t grow back in their place. However, a recent study shows promise for a drug that aims to do just that– regenerate lost teeth.

The Basics of the Study

The study is the result of a combined effort between the University of Fukui and Kyoto University. It found that the antibody of the USAG-1 gene stimulates tooth growth. The full name of the gene in question is the uterine sensitization associated gene-1.

The study from Kyoto University looked specifically at mice and ferrets who suffered from tooth agenesis, a congenital condition that causes the absence of all or some teeth.

Choosing Which Gene to Study

This study built on existing dentistry knowledge concerning agenesis, including genetic causes. A topic of interest for many years, scientists hoped that looking at the genetic causes of tooth agenesis could help adults with these congenital conditions.

Katsu Takahashi, one of the study’s lead authors and a Kyoto University Graduate School of Medicine senior lecturer, mentions that we already knew which fundamental molecules are linked to tooth development. Among the various molecules, two of them are Wnt and BMP (bone morphogenetic protein).

These two hormones do more than just influence tooth development, they’re involved in the earliest stages of embryotic development. At this stage in development, the hormones modulate tissue and organ growth.

While it’s known these hormones are involved in tooth production, they aren’t ideal candidates for regenerating teeth. That’s because their involvement in other organ and tissue growth means that any changes to the hormones could potentially affect the entire body.

The team behind the study strategically left those hormones alone and instead looked for a common factor. USAG-1 was a good option because it antagonizes both of those.

Going into the study, the team already knew that when you suppress the USAG-1 gene, teeth grow to some extent. They just didn’t know how well it would work.

More Details on the Study

Once the team decided to focus on USAG-1, it chose to examine several of its monoclonal antibodies. Monoclonal antibodies are frequently found in arthritis and cancer treatments, as well as in vaccine development.

The team began by trying various antibodies. Some of the antibodies confirmed why a remedy based on BMP or Wnt molecules wouldn’t work. The fact that mice given some of the antibodies had low rates of birth and survival reenforced this theory.

The Successful Antibody

As research continued, the antibody found with the most promise only disrupted USAG-1 from interacting with BMP; it did not affect the Wnt molecule whatsoever. After seeing initial success with this antibody, the team expanded its focus on it. The team quickly found BMP signaling in mice determines how many teeth the rodents grew. The scientists also discovered that giving the mice just one dose of this antibody could generate a new tooth.

After confirming the results in mice, the researchers then confirmed the same results in ferrets.

Future Steps

The USAG-1 antibody shows promise for regenerating missing teeth, especially from congenital conditions. However, there are still several steps before the team can start looking at tests on humans.

Ferrets were a productive step in that direction since their dental patterns are actually similar to those of humans. Next, researchers plan to complete similar tests on dogs, pigs, and other animals.

What It Teaches Researchers About Future Studies

This study was the first to connect monoclonal antibodies, such as the one in question for USAG-1, to tooth regeneration. This means that it can potentially inspire a new direction for research. In the future, new research may look for additional monoclonal antibodies capable of delivering similar effects or discover unique ways of using the same antibody.

At the very least, the study shows promise for treating congenital tooth agenesis in the future.

What This Means for Humans

To put the demand for regenerating lost teeth in perspective, consider approximately 1% of adults have fewer than the normal 32 teeth due to congenital conditions. The study on the new drug looked specifically at mice with congenital conditions. As such, experts are optimistic that the results can apply to humans as well.

If the upcoming tests on animals go well, the team can eventually move onto human testing. If successful, the antibody can become the basis of a treatment that offers an alternative to implants, dentures, and other current treatments.

Author: Cedric Jackson writes about a variety of topics, including dentistry and medicine.

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