In the first study of its kind, University of Florida College of Dentistry researchers are testing the power of a natural human hormone to biochemically move teeth faster and less painfully during orthodontic treatment.
“Most of orthodontics has traditionally dealt with physics, the biomechanics of applying a force against a tooth to move it,” said study investigator Timothy Wheeler, DMD, PhD, Professor and Chairman of Orthodontics. “Ours is the first study to use a naturally occurring hormone, recombinant human relaxin, to biochemically augment tooth movement and retention.”
Relaxin is best known as the hormone that helps women’s pelvic ligaments stretch in preparation for giving birth. It does this by softening collagen and elastin in the tissues, loosening strong, cord-like fibers until they have the consistency of limp spaghetti noodles.
That ability prompted researchers to consider relaxin a possible way to accelerate tooth movement and prevent relapse, a condition where the tooth migrates back to its original position after braces are removed.
“You can imagine normal collagen and elastic fibers to be like rubber bands that attach to the tooth to hold it in place,” said Dr. Wheeler. “Those tissue fibers resist the force of the orthodontic treatment applied to move the tooth and, when that force is removed, say when the braces are taken off, the elasticity of the tissues springs the tooth back into position.”
UF researchers will evaluate whether injecting relaxin into the gums will loosen the collagen and elastic fibers and reorganize them so teeth can move more freely into orthodontic alignment. Once the teeth have been moved, researchers will administer another injection of relaxin under the premise that it will further soften gum tissue fibers, preventing them from pulling teeth back into their original position.
The study will be the first of many to test the hormone as an orthodontic therapy, and it is hoped the drug could cut treatment time in half and eliminate the need for retainers after braces have been removed. The issue of retention—a term used to indicate the tooth remains in the position to which it has been moved without relapse—is a crucial aspect of the study. For most patients, retainers are a lifetime commitment, and when patients don’t wear retainers as prescribed, teeth gradually relapse, nullifying years of orthodontic treatment and expense.
An important goal of future studies is to determine dosage and timing of drug delivery as well as delivery methods other than injection. The patent for the drug, which received the green light from the Food and Drug Administration last April for testing in human subjects, is owned by BAS Medical, a California-based company. BAS Medical is the sponsor of the UF study, which will establish safety and proof of principle on 40 people before a series of multicenter studies could begin testing the drug on hundreds worldwide.
“This is the first step orthodontics has taken to deal with the biologic control of tooth movement, and what the final product will be is hard to tell at this point. Obviously, we want to make it easily available, easily delivered, and as pain-free as possible,” said Dr. Wheeler. “This initial proof of principle trial will help us define how to accomplish that."