Artificial intelligence can help to create customised dental crowns within seconds, team led by HKU
Dental crowns are recommended for patients with damaged teeth, either as a result of accidents or injuries, or for those who need root canal surgery to treat infections.
Currently, it takes about five to 15 minutes to design a crown, using software where crown templates are fine-tuned to better suit the patient, according to lead researcher James Tsoi Kit-hon, an associate professor in dental materials science at HKU.
But there are no universal standards for the design of the chewing surface of the dental crown. Current artificial crowns also mainly rely on a try-on to see if patients feel any discomfort.
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Tsoi said crowns designed using these existing methods were often too large or too thin. “When a crown is too big, it won’t fit the patient, who then will have to wait for another crown to be made and try it on. If it is too thin, it could break during the manufacturing process or become worn out in a short time.”
“We should balance the lifespan and the functionality of the dental device. Now generative AI comes into play to optimise both factors,” he said.
The team of researchers from HKU, ShanghaiTech University, Drexel University and the University of Minnesota in the United States, and Britain’s University of Manchester published their findings in the peer-reviewed journal Dental Materials in March.
Study author Ding Hao, a postdoctoral fellow at the HKU faculty of dentistry who researches clinical artificial intelligence, said the AI algorithm consisted of a generator which produced crown designs and a discriminator that could distinguish between real teeth and AI-generated ones.
“We trained the generator to create crowns based on 600 sets of natural and healthy dental casts, which were then cross-checked by the discriminator. The generator went through 150,000 cycles of training to hone its designs which appeared so close to natural teeth that the discriminator could no longer tell them apart,” Ding said.
In the study, the team found that AI-generated crowns were more similar to natural teeth in terms of their shape and functions than artificial crowns created with conventional methods.
The HKU-led team said their breakthrough was a key step towards leveraging the dental industry in the Greater Bay Area, which covers the Pearl River Delta, including Hong Kong, and produces 25 to 30 per cent of dental prostheses globally.
Tsoi said the team was in touch with dental laboratories for the AI algorithm to be potentially licensed for use in the Greater Bay Area.“If a dental lab is interested in using our technology, scientists there can train the algorithm with their own data and turn it into their know-how,” Tsoi said. He said this approach could protect patient privacy because the lab or clinic would be the one training the algorithm locally, without transferring its data to a third party.
China produced 415 million dental prostheses in 2021, most of which were exported, according to the Intelligence Research Group, a Beijing-based consulting firm.
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Crystal Chen Yanning, a PhD student in dental materials science at HKU who is also part of the research group, said the team was recruiting patients in need of posterior single crown restoration for a clinical trial. This will come with two years of follow-up to compare the performance of AI-designed crowns with conventional ones, and different ceramic materials for crowns.
“We focus on the first molar, or sixth tooth from the midline, which is key for chewing,” Chen said. “There are raised points on the crown called cusps and pits named fossae … Every patient has different oral conditions. Extracting features of their cusps and fossae helps to generate their individualised crowns
The team said their next step would be to use the software to produce dental prostheses such as bridges – which are used to fill a gap from missing teeth – and dentures.
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