New dental membrane goes from hard to soft and back again for a tight fit during implantation

May 4, 2021
A malleable dental membrane promises to make many treatments easier. (Pexels/Andrea Piacquadio)

A malleable dental membrane promises to make many treatments easier. (Pexels/Andrea Piacquadio)

Researchers are seeking a patent for an implant known as a dental membrane that is designed to be both flexible and sturdy, combining the advantages of two traditional kinds of membranes used in people with gum disease.

The new implant can transform from a firm sheet into a pliable putty and then harden again depending on the surrounding temperature and moisture levels, and has so far been tested in anatomical models.

"This polymer thus provides clinicians with versatile products with a combination of properties that simply was not available until now," the researchers wrote in the patent application for the device, which was published by the World Intellectual Property Organization on March 25.

Periodontitis, or gum disease, affects nearly half of adults over 30 in the United States. If left untreated, it can lead to loose and lost teeth. When the bacteria that cause periodontitis enter the bloodstream, they can also exacerbate respiratory and cardiovascular diseases, rheumatoid arthritis and diabetes.

For those who do seek treatment, during a procedure called guided bone regeneration, dental membranes are inserted into the mouth as a barrier between the gums and a wound or bone defect caused by periodontal disease. These membranes are most commonly used in preparation for a tooth implant, said device co-inventor Joachim Kohn, an emeritus professor of chemistry at Rutgers University and president of the International Union of Societies for Biomaterials Science and Engineering.

The stiff membrane is needed because the soft tissue grows much faster than bone and, if they aren't kept apart, will invade the wound and fill it with scar tissue instead of the bone that's meant to be regrowing.

Dental membranes are made from a range of materials that include metal, collagen and plastics. One type, known as degradable or resorbable membranes, isn't removed after being placed in the mouth; it naturally breaks down over time and is absorbed by the body.

"But they are flimsy and they don't really keep their shape enough to protect the empty space where you want to grow bone," Kohn said.

Non-degradable, or non-resorbable, membranes are much stronger but must eventually be surgically removed. 

The dental membrane that Kohn and his colleagues developed is made using the amino acid tyrosine, commonly encountered in cheese, and other naturally occurring nutrients and materials classified as safe by the U.S. Food and Drug Administration, he says.

The polymer — a substance made from large molecules composed of repeating smaller units — starts out as a firm, whitish sheet that resembles lightly frosted glass. 

"As soon as you warm it up a little bit by holding it into your hand or ... blowing some hot air over it, it becomes really nice and soft," Kohn said. "You can shape it into whatever shape you need to create a tight fit between the bone and the empty space."

When immersed in water at temperatures of around 37 degrees Celsius, which Kohn and his team used to mimic warm saliva in the mouth, the polymer hardens again after about 10 minutes.

"Now it stays hard, so it has basically combined the advantages of the soft, degradable materials with the strength of the non-degradable membranes," Kohn said. "And since it's designed to be degradable, you don't need to take it back out again."

The researchers practiced inserting the implant into a plastic anatomical model of the human mouth with a pit carved out to represent bone defects. In this simulated procedure, the device could be implanted as successfully as traditional dental membranes. 

However, Kohn says, this experiment doesn't reveal how well the membrane will perform after implantation. The next step will be to test the membrane in animals. 

Kohn and his colleagues are searching for companies to further develop the membrane and prepare it for commercial use. At this point, he says, it's unclear how the cost of their device will compare with traditional dental membranes.

"This is a rather young and early-stage project," Kohn acknowledged. 

The new membrane builds on previous work his laboratory has done to design polymers for several medical applications, including a mesh pouch that fits around pacemakers and releases antibiotics after they are inserted to prevent infection. 

Kohn says the polymer his team developed for the new dental membrane could potentially also be used to make implants for other parts of the body.

The National Science Foundation and National Institutes of Health provided funding for the invention.

The application for the patent, "Degradable phase changing polymers for dental/medical applications," was filed July 17, 2020, to the World Intellectual Property Organization. It was published March 25 with the application number PCT/US2020/042518. The earliest priority date was Sept. 17, 2019. The inventors of the pending patent are Joachim Kohn, Rutgers University; Amir Fakhrzadeh, Flemington & East Brunswick Family & Cosmetic Dental Group; and Julian Chesterman, On Demand Pharmaceuticals, Inc. The assignee is Rutgers, The State University of New Jersey.

Parola Analytics provided technical research for this story.

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