Shell extract helps rebuild pearly whites


© Shutterstock

Researchers in China have shown that the organic component of mother of pearl can help repair damaged teeth, by acting as a template for the mineralisation of tooth enamel.

Tooth enamel is made up of rod-like crystals of hydroxyapatite, a calcium phosphate mineral. It is the hardest tissue in the body, but is susceptible to erosion by food and bacterial acids. Once gone, it never naturally reforms, and cavities must be fixed using manmade materials. Methods of artificially rebuilding enamel often involve extreme temperature, pressure or pH conditions that make them impractical for clinical use.

Researchers from the Chinese Academy of Sciences and Fujian Medical University, both in Fuzhou, are working towards a more feasible solution using the natural composite, nacre (mother of pearl), from the inside of mollusc shells.

Nacre is composed of layers of aragonite, a form of calcium carbonate, separated by an organic matrix of proteins and biopolymers called the Water Soluble Matrix (WSM). The WSM acts as a template for aragonite crystal growth during nacre formation, so the researchers thought it might also be able to influence the structure of hydroxyapatite crystals in enamel. They tested this using extracted human molars that had been deliberately damaged with a strong acid.

The teeth were immersed in a solution containing the isolated nacre WSM from mussel shells, along with calcium and phosphate ions, for three days. Scanning electron microscope images revealed that hydroxyapatite crystals with the correct shape and orientation formed on the surface of the tooth. The new ‘enamel’ was also similar to the real thing in terms of smoothness and hardness. Without the WSM, the crystals that formed were randomly orientated.

‘Our study demonstrates that WSM is an effective template for hydroxyapatite remineralisation,’ says Zanyong Zhuang, one of the researchers involved. ‘It is much cheaper and easier to extract than other protein templates, and is a natural agent that would be physiologically safe in clinical restoration.’

Zhuang admits, however, that there are many other things to consider when dealing with teeth in situ. Paul Anderson from the Institute of Dentistry at Queen Mary University of London, UK, agreed that further experimentation is needed. ‘This work is intriguing,’ he says, ‘but the mechanism of enamel growth has been well studied, and the [template] mechanism proposed here seems to contradict that. Clinical enamel repair is still a very long way off.’

References

X Li et al, CrystEngComm, 2013, DOI: 10.1039/c3ce26947g


Related Content

Human enamel mimic whitens teeth

24 June 2013 Research

news image

Fluorapatite crystals can non-abrasively restore tooth colour

Patching up tooth enamel

25 January 2011 News Archive

news image

Scientists have been able to rebuild eroded tooth enamel with a hydrogel

Most Read

Antimicrobial resistance will kill 300 million by 2050 without action

16 December 2014 News and Analysis

news image

UK report says resistance will cost global economy $100 trillion

Cutting edge chemistry in 2014

10 December 2014 Research

news image

We take a look back at the year's most interesting chemical science stories

Most Commented

Smart skin for prosthetic limbs senses heat and touch

12 December 2014 Research

news image

Ultra-thin plastic skin can bend and flex without affecting the skin's ability to detect stimuli

Chemistry behind the ‘blue man’ unlocked

1 November 2012 Research

news image

Biochemical model suggests that silver ions, not nanoparticles, cause a rare skin complaint