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Abstract Background Dental caries is a major public health problem in many countries. Since the last territority-wide dental survey of Hong Kong preschool children was conducted in 2001, a survey to update the information is necessary. This study aimed to describe the dental caries experience of preschool children in Hong Kong and factors affecting their dental caries status. Methods A stratified random sample of children from seven kindergartens in Hong Kong was surveyed in 2009. Ethical approval from IRB and parental consent was obtained. Clinical examinations of the children were performed by two calibrated examiners using disposable dental mirrors, an intra-oral LED light and ball-ended periodontal probes. A questionnaire to investigate possible explanatory factors for caries status was completed by the children’s parents. Caries experience was recorded using the dmft index. Multifactor-ANOVA was used to study the relationship between dental caries experience, and the background and oral health-related behaviours of the children. Results Seven hundred children (53% boys), mean age 5.3 ± 0.7 years were examined. The mean dmft score of the surveyed children was 2.2 and 51% of them had no caries experience (dmft = 0). Most (>95%) of the decayed teeth were untreated. Statistically significant correlations were found between dental caries experience of the children and their oral health-related habits, family income, parental education level and parental dental knowledge. Conclusions Early childhood dental caries was prevalent among the preschool children in Hong Kong. Their caries experience was associated with their oral health-related behaviours, socio-economic background, and parental education and dental knowledge.

Abstract Objectives To study the dietary behavior and knowledge about dental erosion and self-reported symptoms that can be related to dental erosion among Chinese adults in Hong Kong. Methods Chinese adults aged 25-45 years were randomly selected from a list of registered telephone numbers generated by computer. A telephone survey was administered to obtain information on demographic characteristics, dietary habits, dental visits, and knowledge of and presence of self-reported symptoms that can be related to dental erosion. Results A total of 520 participants were interviewed (response rate, 75%; sampling error, ± 4.4%) and their mean age was 37. Most respondents (79%) had ever had caries, and about two thirds (64%) attended dental check-ups at least once a year. Respondents had a mean of 5.4 meals per day and 36% had at least 6 meals per day. Fruit (89%) and lemon tea/water (41%) were the most commonly consumed acidic food and beverage. When asked if they ever noticed changes in their teeth, most respondents (92%) said they had experienced change that can be related to erosion. However, many (71%) had never heard about dental erosion and 53% mixed up dental erosion with dental caries. Conclusion Hong Kong Chinese adults have frequent intake of food and many have experienced symptoms that can be related to dental erosion. Their level of awareness of and knowledge about dental erosion is generally low, despite most of them have regular dental check-ups. Dental health education is essential to help the public understand dental erosion and its damaging effects.

Background: The application of 38 % silver diamine fluoride (SDF) has been shown to be effective in arresting early childhood caries (ECC). Since SDF is not available in certain countries, some dentists use adjunctive application of 25 % silver nitrate (AgNO3) and 5 % sodium fluoride (NaF) to arrest ECC. This randomised controlled trial will systematically compare the efficacy of a 25 % AgNO3 solution followed by 5 % NaF varnish with that of a 38 % SDF solution in arresting ECC when applied at half-yearly intervals over a 30-month period.Methods/design: This study is a randomised, double-blinded, non-inferiority clinical trial. The hypothesis tested is that adjunctive application of 25 % AgNO3 followed by 5 % NaF is at least not appreciably worse than a 38 % SDF in arresting ECC. Approximately 3100 kindergarten children aged 3-4 years will be screened and at least 1070 children with caries will be recruited. This sample size is sufficient for an appropriate statistical analysis (power at 90 % (β = 0.10) with a 2-sided type-I error of α = 0.05), allowing for an overall 20 % drop-out rate. The children will be randomly allocated into 2 groups to treat their caries over a 30-month period: Group A - biannual adjunctive application of a 25 % AgNO3 solution and a 5 % NaF varnish, and Group B - biannual adjunctive application of a 38 % SDF solution followed by a placebo varnish. Clinical examinations will be conducted at 6-month intervals. Primary outcome measured is the number of active caries surfaces which are arrested. Information on confounding factors such as oral hygiene habits will be collected through a parental questionnaire.Discussion: We expect that adjunctive application of 25 % AgNO3 solution and 5 % NaF varnish and of 38 % SDF solution can both effectively arrest ECC. Lower concentrations of silver and fluoride are contained in 25 % AgNO3 and 5 % NaF, respectively, than in 38 % SDF; therefore, AgNO3/NaF are more favourable for use in young children. Because its use for caries management is painless, simple, low-cost, and approved in many countries, AgNO3/NaF could be widely recommended and promoted as an alternative treatment to conventional invasive management of ECC.Trial Registration: ClinicalTrials.gov: NCT02019160 . Date of registration: 11 December 2013. [ABSTRACT FROM AUTHOR]