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Oral check-ups of a representative sample of 12-year-old children showed low rates of tooth decay but high rates of early erosion. 

A large proportion of Hong Kong’s primary school children aged 12 years have begun to lose some of their tooth surfaces because of erosion by acid in their diet, according to a study published in the journal BMC Public Health by researchers at the HKU Faculty of Dentistry.

Three-quarters of the 600 12-year-old primary school children who took part in the study showed early signs of dental erosion. In addition, one-fifth of the children had past or current tooth decay. The likelihood of tooth decay and the severity of dental rosion were associated with the frequency of drinking certain drinks.

The findings lead the research team to recommend: “Screening programmes can be provided to identify risk groups for early preventive measures. This can strategically enhance the cost-effectiveness of dental treatment”.

Noting that children are particularly prone to dental erosion, which can lead to tooth sensitivity, reduced ability to chew, altered appearance, and complex and costly treatment, the team aimed to investigate the dental health of a sample of children who were representative of all 12-year-olds in Hong Kong. Hence, the researchers randomly selected one primary school on Hong Kong Island, two in Kowloon, and four in the New Territories, to roughly match the ratio of children living in those three districts.

A total of 600 children aged 12 years received oral examinations; 53% of them were boys, and 60 children were in Hong Kong, 234 in Kowloon, and 306 in the New Territories. Questionnaires that had been completed by the parents showed that one-fifth of the children drank soft drinks or fruit juice at least once every 2 days and about one-seventh drank vitamin C drinks at least once every 2 days.

Of the 600 children, 21% had any current or past dental decay (teeth with untreated decay, missing teeth because of decay, or filled teeth). The average number of affected teeth per child was about 0.3, and half of these cases were decayed teeth that remained untreated. Still, the prevalence of any tooth decay in Hong Kong was lower than the reported figures for Cambodia, mainland China, and Thailand, the authors comment.

Statistical analysis revealed that girls had higher odds of experiencing tooth decay than boys (odds ratio [OR], 1.751). Children who drank soft drinks or vitamin C drinks at least once every 2 days had double the odds of tooth decay (OR, 1.952 and 2.157, respectively) when compared with children who drank such drinks less frequently.

When the mouth was examined as six regions (sextants), the average number of regions showing any dental erosion was 1.6. Exactly three-quarters of the children showed at least one region with any sign of dental erosion, but no child showed any regions containing severe dental erosion. Only one-quarter of the children had erosion-free teeth in all six regions. Overall, the prevalence of dental erosion was higher in Hong Kong than in southern China, the authors comment.

Statistical analysis revealed that dental erosion had progressed further for children who drank fruit juice at least once every 2 days than for those who drank fruit juice less frequently (beta, 0.377), and for children who had experienced dental decay (caries) than for those who had not (beta, 0.591). The researchers conclude that “many children had early signs of erosion, which was related to fruit juice consumption”, while noting that fruit juices are commonly drunk in Hong Kong as part of what is perceived as a healthy diet. Moreover, they add: “It was plausible that children who had caries consumed more acidic food”.

The authors caution that the method of erosion assessment used (Basic Erosive Wear Examination) may not exclude other forms of tooth wear and does not distinguish between tooth enamel and dentine. In addition, because the parents’ questionnaire did not ask about exact types of acidic drinks, their acidity and amounts drunk, or other possibly relevant risk factors, the authors call for further research on dental erosion. Nevertheless, since Hong Kong has so far lacked data on dental erosion in children and young adults, the researchers hope their current findings “would be useful to the dental profession and the government for planning dental services in Hong Kong”.

This research was supported by the Health and Health Services Research Fund of the Food and Health Bureau of the Hong Kong Special Administrative Region. The research team members were Dr Shinan Zhang, Dr Alex MH Chau, Prof Edward CM Lo (Chair Professor of Dental Public Health), and Dr Chun-hung Chu (Clinical Associate Professor in Community and Family Dentistry).

Source: Zhang S, Chau AMH, Lo ECM, Chu CH. Dental caries and erosion status of 12-year-old Hong Kong children. BMC Oral Health 2014;14:7.
Medline link to research article: http://www.ncbi.nlm.nih.gov/pubmed/24397565
Free full-text research article: http://www.biomedcentral.com/1471-2458/14/7

For more information about the HKU Faculty of Dentistry, please visit http://facdent.hku.hk; Facebook page: www.facebook.com/facdent

For a Faculty Factsheet on dental acid erosion, please see: http://facdent.hku.hk/engagement/community/pdf/DentalAcidErosion.pdf

Media enquiries:
Dr Chun-hung Chu, Clinical Associate Professor in Community and Family Dentistry, HKU Faculty of Dentistry; Tel: 2859 0287; E-mail: chchu@hku.hk
Mr Oi-sing Au, Communications & Development Officer, HKU Faculty of Dentistry; Tel: 2859 0454; E-mail: singau@hku.hk