Sociodemographic background
There are a number of studies showing that socioeconomic factors are related to children’s dental caries experience.^16,17,19,21 From 1993 to 2017, all oral health surveys concluded that household income was significantly associated with preschool children’s dental caries experience. Children from families with higher income and whose parents had a higher education level had lower dental caries prevalence. These results indicated that social inequality exists among the dental health of preschool children in Hong Kong. Underprivileged children may have a higher risk of developing caries lesions. Besides, the demographic characteristics also affect the dental caries experience. As Hong Kong was colonized by the British Empire, its culture, foods, and living lifestyles are slightly different from Mainland China. The epidemiological survey conducted in 2009 reported that children who were born in Mainland China had significantly higher dental caries experience than those born in Hong Kong.¹⁶ …

Water fluoridation
…  In Hong Kong, the water fluoridation program was introduced in 1960 with a fluoride level of 0.8 parts per million (ppm). After that, the mean dmft score of the 12-year-old children decreased dramatically from 4.4 in 1960 to 1.5 in 1968.^15,30 Subsequently, the concentration of fluoride increased to 1.0 ppm in 1976.³¹ However, the results of this survey indicated that the prevalence of dental fluorosis among 7- to 12-year-old children also increased to 64%.³⁰ Therefore, the concentration was adjusted to be 0.7 ppm in 1986. Later, the epidemiological survey in 1988 reported that the dental fluorosis remained prevalent (47%). Then, the concentration of fluoride was reduced to 0.5 ppm in 1988.³² Until now, the fluoride level has remained at 0.5 ppm in Hong Kong. Optimal fluoride concentration in drinking water was determined by various factors including environmental temperature, daily water consumption, and access to different sources of fluoride.³³ The amount of fluoride ingested during the summer time was higher than that during the winter time.³⁴ For people living in tropical or subtropical regions like in Hong Kong, they tend to consume more water than those living in cooler regions.³⁴

Besides, young children may be at risk of ingesting fluoride from toothpaste which is commercially available and affordable for most of the families. Therefore, the fluoride concentration in Hong Kong has been adjusted to be 0.5 ppm, which is lower than that in the cooler areas such as in the US (0.7 ppm).³⁵ (our emphasis)

Although water fluoridation is one of the most significant dental public health projects benefitting all residents in Hong Kong, the caries statuses of preschool children were unsatisfactory. Additional effective evidence-based oral health programs for preschool children are needed…

Toothpaste
… Prior to the eruption of the first primary teeth, caregivers are asked to clean the infant’s gum with moist gauze or a washcloth wrapped around the finger. From the eruption of the first tooth to age 2 years, children are recommended to have their teeth cleaned with a soft toothbrush with toothpaste. At age 2–6 years, a child can begin to use a pea-sized amount of fluoride toothpaste and brush his or her teeth twice daily.²²

… At present, all Hong Kong residents (100%) usually consume fluoridated tap water daily.²⁵ Fluoride toothpaste is commercially available and is affordable to most of the families in Hong Kong. It is suggested that children can start tooth brushing with fluoride toothpaste at the age of 2 years. The results of the 2011 territory-wide survey study showed that the majority (94.3%) of the children in Hong Kong used toothpaste.²⁰ However, only half of the parents indicated that their children used fluoridated toothpaste, while one-third did not know whether their children’s toothpastes contained fluoride.²⁰

*Read full study at http://fluoridealert.org/wp-content/uploads/chen-2019.pdf