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Drops of the liquid solution are applied to a human tooth. Photo: Zhejiang University

Chinese scientists ‘make first perfect replica’ of tooth enamel

  • New material is almost identical in structure to human enamel, which does not regenerate itself
  • Crystal-like mineral can grow on teeth and last permanently, researchers say

Scientists at a Chinese university say they have discovered the world’s first material that can repair damaged tooth enamel once and last for life.

A few drops of the liquid solution can fix all invisible cracks and wear on an ageing molar, according to researchers at Zhejiang University in Hangzhou, eastern China, whose work was published on Friday in the journal Science Advances.

The material, calcium phosphate ion clusters, can grow a thin layer of protective shield on teeth, the research showed. The transparent, crystal-like mineral has a structure resembling fish scales and a high mechanical strength – almost identical to the enamel on a human tooth.

Its repair of the tooth “would be permanent”, wrote the researchers, led by Professor Tang Ruikang at the university’s chemistry department.

A tooth’s non-repaired left side (darker) and repaired right side (lighter) are compared using a fluorescent chemical. Photo: Zhejiang University

The technology could be developed as an effective remedy in clinical practice for enamel erosion, the main cause of tooth decay, Tang’s team said. Tooth decay affects almost half of the world’s population, costing dental patients in the United States and European Union a combined US$200 billion annually, according to the World Dental Federation.

Enamel, the outer covering of teeth, is the hardest tissue in the human body, protecting teeth during biting and chewing food.

Unlike other tissues such as muscle, bone and skin, enamel is generated by cells that die immediately after completing their job. The human body cannot produce more of them, so when enamel breaks or chips, it will not regenerate itself.

For decades, researchers around the world have conducted studies to seek a solution, but the artificial materials tested previously could not recreate precisely the fine structure of natural enamel, leaving gaps or holes that could cause it to break off real enamel.

Wouldn’t it be nice if our teeth fixed themselves, just like pandas’ do?

Tang’s team claim their new material can grow seamlessly on human teeth. They mixed two different types of repairing material together to form tiny clusters of mineral particles only 1.5 nanometres in diameter – smaller than a strand of human DNA.

Unlike in previous experiments, these clusters could remain stable for a long time without clumping together, making precise reconstruction of an enamel-like structure possible.

Chen Haifeng, associate professor at Peking University’s biomedical engineering department, said that the research was a positive step but that the new material might need improvements before clinical use.

For instance, the artificial layer requires two days to grow, which could be difficult for dentists to schedule with patients.

Many children use so much toothpaste it’s unhealthy, experts warn

The liquid solution contains triethylamine, a toxic substance with a very strong smell, which may pose a health risk, according to Chen. “But it doesn’t mean we can’t do anything,” he said.

The researchers said the chemical would quickly vaporise and none would be left in the teeth after the protective shield had formed.

Some products preventing enamel erosion and decay, such as toothpaste with enamel-strengthening ingredients, are already available in shops.

“Prevention is the best approach,” Chen said. “We should never wait until the damage is done. Our teeth are a miracle of nature. Artificial replacement will never do the job as well.”

This article appeared in the South China Morning Post print edition as: discovery promises end to tooth decay