Dental Tribune Asia Pacific

Nepal teeth to uncover origins of birth defects

By Daniel Zimmermann, DTI
April 28, 2011

HONG KONG/NEW YORK, USA/LEIPZIG, Germany: For Himalaya tourists, the remote village of Jiri in Nepal is just a regular stopover on the way into the mountains. Professor Richard J. Sherwood from Dayton in the US however thinks the small group of natives living there could hold the key to understanding the origin of common birth defects, such as cleft lip or palate.

In a field study, the anthropologist and biomedical expert is currently examining the teeth of hundreds of villagers, which, according to him, could explain one day why the early development of facial properties can go seriously wrong.

The reason why Prof. Sherwood chose such a remote place was pramatic. The population of Jiri had been part of several biomedical studies since the 1980s and, therefore, much of the ground work including genotyping by blood sampling had been already done. In addition, people in Jiri, also called Jirel, have had a homogeneous diet and never received orthodontic care, which are two important factors to study natural variations in the craniofacial apparatus, Sherwood says.

In order to obtain data quickly, he set up a small dental clinic in the village in January last year where local dentists are taking traditional dental casts and sending them to the US regularly. At  Wright State University in Dayton, they are digitally scanned and examined further. Sherwood uses to visit Jiri himself two or three times a year. According to him, there are over 15 people working on the project at the moment including a dentist, dental assistant and physician in Nepal.

"Before we established the dental clinic, there was no local dentist and most people had never seen a dentist in their life." he says. "As part of our study, participants are given a tooth cleaning and general oral exam. We also provide some services, such as fillings, free of charge."

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A pilot study back in 2005 had already produced 200 impressions. Sherwood recently told the newspaper Dayton Daily that he is aiming to take samples from at least one-fifth of Jiri’s current population―about 1,500 people―until funding runs out in 2012. His study has already received more than US$2 million from the National Institute of Dental and Craniofacial Research, a US federal agency based near Washington D.C. and part of the National Health Institute that supports research with the potential to improve oral, dental and craniofacial health.

Sherwood told Dental Tribune ONLINE that he intends to publish preliminary results next year. Through the study of normal variations in the Jiri population he hopes to find genetic clues that could explain why cleft palates develop differently as well as gain new insights into other dental conditions, such as crowding.

According to the American-Speech-Language-Hearing Association, one out of every 700 newborns (more than 6,000) in the US are affected by cleft lip and/or palate each year. In less developed countries like China, reports suggest that tens of thousand are affected, most of which are left untreated, leading to death or, in the majority of cases, lifelong impairments.

Besides genetics, the condition can be also linked to bad health habits, such as smoking, or environmental factors, including exposure of the foetus to drugs, pesticides or radioactivity. For example, after the nuclear power plant incident in Chernobyl in the Soviet Union in 1986, a fivefold increase of cleft lip or palate cases in newborns was registered.

“Abnormalities can be thought of as the extreme ends of the normal distribution in a trait but even relatively minor conditions, for example malocclusions, may have significant impact on the psychological well-being of individuals if they feel self-conscious about how they look,” Sherwood concludes. “If we are able to identify the genetic influences on normal variation it will, of course, have implications on the study of facial abnormalities.”

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