<p dir="ltr"><b>Introduction:</b> Early childhood caries (ECC) is a multifactorial disease influenced by biological, behavioral, and social determinants. Parental behaviors and family environments play an important role in its development and prevention. Using parental support interventions have been proposed as a strategy to promote preventive routines and reduce the burden of disease, particularly in populations at increased risk. However, evidence regarding the effectiveness of such interventions at different stages of the disease trajectory remains limited.</p><p dir="ltr"><b>Aim:</b> The overall aim of this thesis was to improve the understanding of parental support programs for preventing early childhood caries, with particular attention to children at increased risk of disease. It had three specific aims: to evaluate oral health outcomes within a parental support program integrated into child health services; to assess the effect of a phone-delivered motivational interviewing-based intervention following treatment for severe ECC under general anesthesia (GA); and to examine associations between parental psychosocial factors, children's caries burden, and child oral health-related quality of life.</p><p dir="ltr"><b>Materials and methods:</b> This thesis was based on three studies. Study I evaluated oral health outcomes among children participating in an extended home visiting program delivered through collaboration between the Child Health Services and the Social Services in a socioeconomically disadvantaged area. Studies II and III were based on a randomized controlled trial evaluating a parental support intervention delivered by telephone following treatment of severe ECC under GA. Clinical examinations were conducted using the International Caries Detection and Assessment System (ICDAS) for caries registration. Study II assessed caries progression and behavioral outcomes during a two-year follow-up period. Study III examined parental psychosocial factors and children's oral health-related quality of life using questionnaires and path analysis.</p><p dir="ltr"><b>Results:</b> In the early preventive context (Study I), participation in the extended home visiting program was associated with higher reported toothbrushing frequency and a lower prevalence of cavitated caries at 18 months as well as a higher proportion of children remaining caries-free at 36 months. In contrast, in the secondary preventive context (Study II), the motivational interviewing-based intervention delivered by phone did not reduce caries recurrence following treatment under general anesthesia. Caries progression during follow-up was substantial in both the intervention and control group. Study III showed that parental psychosocial factors, including stress, dental fear and dental beliefs, were not significantly associated with the child's caries burden at the one-year follow-up. Baseline caries burden emerged as the strongest predictor of subsequent caries burden. However, participation in the parental support program was associated with improved child oral health- related quality of life as reported by caregivers.</p><p dir="ltr"><b>Conclusions: </b>The findings suggest that the implications of parental support interventions may differ depending on the stage of disease. Early parental support integrated within child health services was associated with improvements in oral health behaviors and differences in early caries outcomes. In contrast, among children with established severe ECC, parental support did not appear sufficient to modify the clinical course of disease but was associated with improved child oral health-related quality of life. These findings highlight the importance of early preventive efforts while illustrating the complex challenges of modifying disease progression once severe early childhood caries has developed.</p><h3 dir="ltr">List of scientific papers</h3><p dir="ltr">I. <b>Brännemo I,</b> Dahllöf G, Cunha Soares F, Tsilingaridis G. Impact of an extended postnatal home visiting programme on oral health among children in a disadvantaged area of Stockholm, Sweden. Acta Paediatr. 2021;110(1):230-236. Published open access under the CC BY NC license. <a href="https://doi.org/10.1111/apa.15457" rel="noreferrer" target="_blank">https://doi.org/10.1111/apa.15457</a></p><p dir="ltr">II. <b>Brännemo I,</b> Hasselblad T, Levinsson A, Dahllöf G, Tsilingaridis G. Phone-based parental support program for caries prevention in children: a randomized controlled trial. JDR Clin Transl Res. 2024;10(3):304-314. Published open access under the CC BY license Commons Attribution 4.0 License. <a href="https://doi.org/10.1177/23800844241296054" rel="noreferrer" target="_blank">https://doi.org/10.1177/23800844241296054</a></p><p dir="ltr">III. <b>Brännemo I,</b> Levinsson A, Hasselblad T, Dahllöf G, Tsilingaridis G. Parental psychosocial factors and children's oral health-related quality of life: data from a caries prevention study with phone- based support. BMC Oral Health. 2025;25(1):94. Published open access under the CC BY license. <a href="https://doi.org/10.1186/s12903-025-05446-z" rel="noreferrer" target="_blank">https://doi.org/10.1186/s12903-025-05446-z</a></p>