Early childhood caries (ECC) remains the single most common chronic childhood disease. Untreated caries can cause tooth loss and compromised dentition. Severe ECC can also influence nutrition intake, cognitive development, general health and quality of life. In Hong Kong, approximately half of 5-year-old children suffer from ECC, and more than 90% of these caries remain untreated. Thus, the development of effective strategies for promoting the oral health of preschool children is warranted. The Faculty of Dentistry of the University of Hong Kong has provided kindergarten-based dental outreach services to selected kindergartens since 2008. In 2020, the project expanded to serve all kindergarten children in Hong Kong. The aim of the service is to improve oral health through the prevention and control of ECC among preschool children. The service provides dental screening and silver diamine fluoride treatment for ECC management. In addition, the parents receive oral health talks, and teachers receive training in delivering regular oral health education at kindergarten. The objectives of this service are to improve oral and general health of preschool children, develop the children’s good oral health-related behaviours, maintain the children’s psychological well-being and reduce the burden on their family. This paper describes this kindergarten-based dental outreach service.

Qualitative research collects non-numerical data that explores human behaviour, attitudes, beliefs and personality characteristics unamendable to quantitative research. The qualitative research questions are open-ended, evolving and non-directional. The study design is flexible and iterative. Purposive sampling is commonly used. The sample size is determined by theoretical saturation. Data collection is generally through in-depth interviews, focus groups and observations. Qualitative research commonly uses thematic analysis and framework analysis, although there is no consensus on analysing qualitative data. The reporting format can be comprehensive, a summary, developmental or selective, subject to the research question. Qualitative research’s potential functions are to describe the form or nature of what exists (contextual), to examine the reasons for or associations between what exists (explanatory), to appraise the effectiveness of what exists (evaluative), and to aid the development of strategies (generative). Qualitative research can be time consuming to conduct because it explores evolving questions; difficult to generalise because it recruits limited participants; and arduous when it comes to making systematic comparisons because responses are subjective. However, qualitative research can provide depth and detail, create openness, simulate people’s individual experiences and avoid pre-judgements. This concise review provides an overview and suggestions for dental researchers when conducting a qualitative study.

In 2021, the World Health Organization included silver diamine fluoride (SDF) as an essential medicine to manage caries in adults and children. SDF was developed in the 1960s, but its use for children became unpopular in Japan because of the decline and low prevalence of early childhood caries. This mixed methods study explored the knowledge, practices and attitudes towards SDF therapy among dentists promoting fluoride use in Japan. It also investigated senior dentists’ perceptions of SDF therapy in Japan. The quantitative study invited all 173 members of the largest organisation promoting fluoride use in Japan to complete a web-based questionnaire survey. Sixty (60/173; 35%) dentists promoting fluoride use in Japan completed the questionnaire survey. All dentists knew of SDF treatment, and 50 (50/60; 83%) used SDF for dental care. Fifty-nine dentists (59/60; 98%) agreed that SDF therapy was simple and quick. All 60 dentists agreed that SDF was effective to arrest caries; 51 dentists (51/60; 85%) agreed that SDF was effective to prevent caries. Most dentists (51/60; 85%) were concerned about SDF’s unaesthetic staining. Fifty-seven dentists (57/60; 95%) used SDF to arrest primary posterior teeth, and 52 dentists (52/60; 87%) used SDF to arrest root caries. However, 25 dentists (25/60; 42%) did not use SDF to prevent caries in permanent teeth. The qualitative study interviewed 12 senior dentists using snowball sampling and achieved data saturation. The dentists opined that SDF therapy was effective, simple, painless, non-invasive and inexpensive. SDF is seldom used in Japan at present because of the unaesthetic black staining and the low prevalence of early childhood caries; however, it can regain popularity by arresting root caries in the aging population.

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Limited data are available regarding the patient-based outcomes of SDF therapy in the kindergarten setting. This study aims to evaluate the dental fear and anxiety (DFA) of preschool children after participating in a school-based outreach service using SDF to arrest early childhood caries (ECC). The study recruited 3- to 5-year-old children with untreated ECC. A trained dentist performed a dental examination and applied SDF therapy to the carious lesions. ECC experience was measured using the dmft index. Questionnaires for parents were used to collect the children’s demographic information and their dental treatment experiences. The children’s DFA before and immediately after SDF therapy was assessed using the self-reported Facial Image Scale (FIS) on a Likert scale of 1 (very happy) to 5 (very distressed). The association between the children’s DFA after SDF therapy and the potentially related factors, including demographic background, caries experience, and DFA before SDF therapy, were analysed using bivariate analysis. Three hundred and forty children (187 boys, 55%) joined this study. Their mean (SD) age and dmft scores were 4.8 (0.9) and 4.6 (3.6), respectively. Most of them (269/340, 79%) never had a dental visit. After SDF therapy, 86% (294/340) of the children exhibited no or low DFA (FIS ≤ 3), whereas 14% (46/340) reported high DFA (FIS > 3). No factor was associated with children’s DFA after SDF therapy (p > 0.05). This study showed most preschool children with ECC exhibited no or low DFA after SDF therapy in a school setting.

In this qualitative study, the researchers explored principals’ perspectives on a free outreach dental service with silver diamine fluoride (SDF) therapy for children in kindergarten. Two researchers recruited kindergarten principals using purposive sampling. They conducted individual semi-structured interviews to collect the principals’ perspectives regarding their adoption of and experience with the service. They manually transcribed the interview verbatim into text and followed a thematic approach for data analysis. The researchers interviewed eight principals. The principals identified the prevalent caries status and importance of oral health promotion for kindergarten children. They acknowledged that the service enhanced dental knowledge, fostered oral hygiene practice and improved children’s oral health. To adopt this service, they needed to ensure adequate capacity to perform the service. They had no concern with staining by SDF because the parents were informed and consented to the SDF therapy. They appreciated the free service provided by a professional team managed by a reputable university. In conclusion, the principals were generally satisfied with the outreach dental service. They realised the necessity of oral health promotion. They found that parents accepted the SDF therapy although the SDF stained their children’s carious teeth. They needed support from their teachers and the children’s parents to run the service.