A root canal ranks high on most people’s list of dreaded dental procedures, and it results in a dead tooth susceptible to further decay. Now US scientists have developed a peptide hydrogel designed to regenerate dental pulp after a root canal, preserving the tooth.
Their research was presented at the recent 256th National Meeting & Exposition of the American Chemical Society.
During a root canal, the dentist drills off the top of an infected tooth to access the soft tissue inside. The dentist then removes the infected dental pulp and fills the space with tiny rubber rods called gutta percha and caps the repaired tooth with a crown.
The team from the New Jersey Institute of Technology wanted to develop a material that could be injected in place of the gutta percha and would stimulate both new blood vessel growth and proliferation of dental pulp stem cells, within the tooth.
Principal investigator Vivek Kumar drew on his previous experience developing a hydrogel that stimulates the former when injected under the skin of rats and mice. The hydrogel, which is liquid during injection, contains peptides that self-assemble into a gel at the injection site. The peptides contain a snippet of a protein called vascular endothelial growth factor, which stimulates the growth of new blood vessels.
Kumar, then a postdoctoral researcher at Rice University, and his co-workers showed that the self-assembling peptide hydrogel stimulated angiogenesis and persisted under the rodents’ skin for as long as three months.
“We asked the question, if we can stimulate angiogenesis in a limb, can we stimulate angiogenesis in other regions that have low blood flow?” Kumar said. “One of the regions we were really interested in was an organ in and of itself—the tooth.”
So Kumar and colleague Peter Nguyen added another domain to the self-assembling angiogenic peptide: a piece of a protein that makes dental pulp stem cells proliferate.
When the team added the new peptide to cultured dental pulp stem cells, they found that the peptide not only caused the cells to proliferate, but also activated them to deposit calcium phosphate crystals—the mineral that makes up tooth enamel. However, when injected under the skin of rats, the peptide degraded within one to three weeks.
“This was shorter than we expected, so we went back and redesigned the peptide backbone so that we currently have a much more stable version,” Kumar said.
Now, the team is injecting the peptide hydrogel into the teeth of dogs that have undergone root canals to see if it can stimulate dental pulp regeneration in a living animal. If these studies go well, the researchers plan to move the hydrogel into human clinical studies.