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04 WORLD NEWS Dental Tribune Asia Pacific Edition | 12/2017 Parrotfish tooth research may ring in new era of biomaterial development By DTI SINGAPORE/BERKELEY, USA: The achievements of science are evolving constantly. However, there are many natural wonders that humanity has not been able to mimic yet. Among these are parrotfish teeth, which are one of the strongest and most abra- sion-resistant in the animal world. Investigating their structural make-up, a team of researchers has now determined the underly- ing properties that make the fish’s teeth strong enough to even bite stony corals. “Parrotfish teeth are really good all-round biters of hard things, and few other teeth in na- ture are harder or stiffer,” said lead author Dr Matthew Marcus from the Lawrence Berkeley National Laboratory in California. To feed, the investigated steephead par- rotfish Chlorurus microrhinos bite off corals and assimilate the or- ganic material within it. To do so, these fish have two sets of teeth: one for biting corals and a pharyn- geal set for grinding and chewing the bitten-off material. Aiming to find out what makes the fish’s teeth so resistant, the re- assemble into bundles interwo- ven like the warp and weft threads in fabric. The fibres gradually de- crease in size from 5 μm at the back to 2 μm at the tip, and accord- ing to Marcus, it is this size de- crease that makes the tooth struc- ture so hard. “The results also show that in nature, complex structures have evolved to carry out specialised extraordinary functions, like bit- ing coral, using simple, unsophis- ticated materials,” Marcus told na- notechweb.org. “Man-made mate- rials, in contrast, usually do the opposite—that is, we use high- tech materials with a very basic structure.” According to the researchers, the techniques used in the study could be employed to study human bone and teeth more thoroughly and help in the de- velopment of new biomimetic materials. The study, titled “Parrotfish teeth: Stiff biominerals whose microstructure makes them tough and abrasion-resistant to bite stony corals”, was published online ahead of print on 20 Oc- tober in the ACS Nano journal. Parrotfishes are named for their unique dentition, which forms a parrot-like )eak. Their teeth contain fluorapatite, which is among the stiffest and hardest )iominerals known and can also )e found in human teeth that have )een exposed to fluoride. searchers first measured their me- chanical properties in nano- indentation experiments. After- wards, they performed chemical analysis with a variety of tech- niques, including scanning elec- tron microscopy with energy-dis- persive X-ray analysis and elec- tron probe micro-analysis. As reported by nanotechweb. org, the results showed that it is not the material of parrotfish teeth that is special, but the ar- rangement of the crystals of the teeth. Studying the structure, the researchers found that the enam- eloid nanocrystals co-orient and Dental radiographs can reveal vitamin D deficiency By DTI HAMILTON, Canada: Human teeth hold vital information about vita- min D deficiency, and Canadian anthropologists have now found that this serious but often hidden condition can be detected on a simple dental radiograph. Identi- fying individuals who may have experienced vitamin D deficiency has significant potential for fur- ther understanding of the factors that may have compromised the health of people in the past. McMaster University re- searchers Prof. Megan Brickley, Lori D’Ortenzio and their col- leagues had previously discovered that human teeth hold a detailed and permanent record of serious vitamin D deficiency. This appears as microscopic deformities in den- tine and can be extremely valua- ble for understanding precisely when people, even those who lived centuries ago, were deprived of sunlight, necessary for the body’s production of vitamin D. The record is preserved by enamel, which protects teeth from breaking down, unlike bones, which are subject to decay. The problem with looking for such de- formities is that a tooth must be cut open to observe the patterns that form a lifetime’s vitamin D record, and the supply of post-mortem teeth available for study is limited. To avoid wasting precious specimens, the researchers looked for a way to isolate teeth for fur- ther investigation. By using radio- graphs to study the readily ob- servable shapes of the pulp horns, the researchers found a consist- ent, recognisable pattern that could prove helpful both to their Radiograph showing vitamin D deficiency: Chair shaped, constricted pulp horns in the left first mandi)ular molar and a second mandi)ular molar ()lack circles). studies of archaeological teeth, as well as to people who may not re- alise they are suffering from vita- min D deficiency. The pulp shape in a healthy person’s tooth resembles an arch topped by two cat ears, but in a person who has had a severe defi- ciency of vitamin D is asymmetri- cal and constricted, typically look- ing like the profile of a hard- backed chair. D’Ortenzio and Brickley’s pre- vious research had suggested such a recognisable pattern, and their examination of both historic and current teeth proved that ra- diographic images are consistent and reliable indicators of prior deficiency. “It was a real Eureka! It wasn’t just that it looked different. It was different,” remembered Brickley, who holds the Canada Research Chair in Bioarchaeology of Human Disease. “I think it’s really important. It was a piece of work that aimed to look more at past in- dividuals, but it has the potential to contribute to modern health- care as well.” Since the consequences of vitamin D deficiency can be se- vere—especially in terms of bone health—knowing who has had a deficiency can help identify peo- ple who may have ongoing issues to prevent worse damage, the re- searchers said. If regular dental ra- diographs show a problem, blood tests can confirm whether there is a current deficiency. Knowing more about ongoing vitamin D deficiency can also help to determine what is the best bal- ance between protecting people from harmful UV rays and mak- ing sure they get enough sun to maintain a healthy level of the vital nutrient. The study, titled “The rachitic tooth: The use of radiographs as a screening technique,” was pub- lished online on 7 November in the International Journal of Paleo- pathology. © J.S. Lamy/Shutterstock.com© McMaster University