West Virginia University is one of three U.S. universities testing a new technology that incorporates “shape memory” material for clear plastic dental aligners, an alternative to traditional metal braces.
“To make these materials that actually have memory is a big breakthrough,” said Dr. Peter Ngan, Branson-Maddrell Endowed Professor and chair of the WVU School of Dentistry Department of Orthodontics. “Having this technology allows us to start doing research on this material which will be the future direction of making aligners that are not available yet commercially.”
Silver braces have been around for about 100 years, while clear aligners have been in the marketplace for about two decades. However, Ngan said most orthodontists don’t think plastic performs as well as metal.
“The clear aligners still need to be improved to the point that there are two materials — clear aligners and metal braces — that are as good as each other,” he said. “Our goal is to see if we can get both of these treatments to achieve the same goal and also make sure the patient is happy.”
With funds from endowments created by orthodontic alumni and other friends of the School of Dentistry, researchers purchased 3D printers from Graphy Inc. The Korean-based company developed the technology that uses thermoplastic to make the aligners.
“This isn’t a hard plastic, so if you take it out and put it in hot water it will shrink and soften up, and that will make it easy to put back in your mouth,” Ngan said. “Then the mouth temperature will harden it back to its original shape and move the teeth accordingly.”
Thermoplastic’s softness makes it a better fit than metal for pairing with “tooth attachments,” restorative materials that clinicians glue onto teeth. Thermoplastic also allows for adding layers, varying the thickness of each aligner in order to reposition a patient’s teeth more efficiently.
Unlike their metal counterparts, the aligners can be removed so patients can brush and floss.
To make a thermoplastic aligner, a patient’s mouth is scanned and a dental mold is created, as with other plastic aligners. But instead of sending the scan out to a company that will manufacture the aligner, orthodontists using the Graphy printer can immediately make aligners onsite in their dental practices.
“It’s as convenient as having a Xerox machine,” Ngan said.
To advance their understanding of how thermoplastic can be used in orthodontics, Ngan and his team are collaborating with the WVU Benjamin M. Statler College of Engineering and Mineral Resources. Sam Mukdadi, associate professor of mechanical, materials and aerospace engineering, is conducting several assessments with mechanical engineering students.
For example, Egon Mamboleo, a graduate teaching assistant from Morgantown, simulated the biomechanical behavior of the aligners and the stress response of the teeth, periodontal ligaments and surrounding bones. Mamboleo is studying the shapes and orientations of tooth attachments to show how aligners can be specifically refined for each patient.
“Thermoplastic aligners exhibit better grab and contact with the teeth and, therefore, can achieve higher efficacy in moving teeth than conventional aligners,” Mukdadi said.
Ngan added that he believes about 50% of orthodontic patients will be using clear aligners within the next few years.
“We’re comfortable using silver braces, it’s just that more adults are focusing on their oral health and they don’t want to look like teenagers with silver in their mouth,” Ngan said.
“These are suitable for all ages so it’s the patient’s choice. When our residents and graduate students go into practice, they will be using this in their offices.”
