Impact of kindergarten dental outreach service in primary school students

Abstract

Introduction: A substantial proportion of dental caries in primary teeth remains untreated among Hong Kong children. The Faculty of Dentistry, University of Hong Kong, has been providing kindergarten outreach dental services (KDOS), comprising oral examination, oral health education, and silver diamine fluoride application. Objectives: 1) To evaluate the association between KDOS and various oral health-related outcomes, including dental caries experience, treatment received, and oral health-related quality of life (OHRQoL) in primary school students; 2) To explore the association between caries in primary teeth and subsequent caries risk in permanent teeth. Methods: A retrospective observational study was conducted. Grade 3 or 4 primary school students participating in the School Dental Care Service were recruited from four school dental clinics in 2022. A cross-sectional questionnaire survey was administered to children and their parents to collect self-reported data. Children's clinical examination and treatment records were provided by the Hong Kong SAR government Department of Health. Children’s OHRQoL was assessed using two Child Perceptions Questionnaire (CPQ) short forms. The stabilized inverse probability of treatment weight and overlap weighting were used to address confounding across different objectives. The stabilized inverse probability of censoring weight was used to account for missing data. Results: Among 964 children (8 to 10 years old when recruited) with complete clinical data, 18.7% and 81.3% were classified as the exposure and non-exposure groups, respectively. From Grades 1 to 3, the respective prevalences of caries experience were 54.6%, 60.7%, and 57.6%, and the mean dmft (standard deviation, SD) scores were 2.5 (3.1), 2.4 (2.8), and 2.0 (2.4). After adjustment, the exposure group showed a lower prevalence of decayed primary teeth in Grade 3 (difference -9.8%; 95% CI -18.0 to -1.6; P=0.019) and a lower mean number of decayed primary teeth in Grade 2 (difference -0.4; 95% CI -0.7 to -0.1; P=0.017). The exposure was not significantly associated with treatment received. Among 883 children with complete questionnaire data, the median (Q1, Q3) total scores were 3.0 (2.0, 5.0) for CPQ-ISF:8 and 2.0 (1.0, 4.0) for CPQ-RSF:8. After adjustment, no significant association was observed between exposure and overall OHQoL. However, exposure was significantly associated with a reduced oral symptoms subscale score by CPQ-RSF:8 (mean difference -0.25; 95% CI -0.49 to -0.01; P=0.043). Item-level analyses also revealed that the exposure group reported significantly less frequent mouth sores (adjusted common odds ratio 0.62; 95% CI 0.44 to 0.88; P=0.008). Compared with children without prior caries in primary teeth, those with caries experience in primary teeth in Grade 1 were nearly three times as likely to develop caries in their permanent teeth in Grade 3 (adjusted risk ratio 2.8; 95% CI 1.7 to 4.8; P<0.001). Conclusion: The KDOS demonstrated an encouraging long-term impact in preventing caries in primary teeth among primary school children. The overall OHRQoL was favorable among the study children. KDOS was associated with better OHRQoL in the oral symptoms domain and the mouth sores item. Caries in primary teeth increased the risk of caries in permanent teeth.