Malocclusions are common and comprise a range of different types, such as crowding and increased overjet. Approximately 70% of children and adolescents present with some degree of malocclusion, often of mild severity. In Sweden, publicly funded orthodontic treatment is provided free of charge to about 30% of children and adolescents. Treatment is prioritised for those with the greatest treatment need, based on the severity of malocclusion.

Untreated malocclusions may impair oral health-related quality of life (OHRQoL). The magnitude of the impact may differ depending on the type and severity of malocclusion; however, current knowledge is limited and largely based on earlier research in need of updating. Findings may also vary depending on how OHRQoL is measured. The orthodontic-specific instrument Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ) was developed to assess the impact of malocclusion on OHRQoL; however, a Swedish version was not previously available.

To determine malocclusion severity and eligibility for orthodontic treatment, various assessment methods are used in both clinical practice and research. Photographs are increasingly used in place of clinical examination or dental study models, although it is not yet established whether photograph-based assessments perform equally well.

Although dental care for children and adolescents is publicly funded and free of charge in Sweden, disparities in both oral health and access to dental care persist. However, less is known about whether orthodontic treatment uptake differs between population groups.

This thesis investigated malocclusion in adolescents, its association with OHRQoL, and how orthodontic treatment is distributed within the public dental care system. The work was conducted using several approaches. Previous research was synthesised in a systematic review to examine associations between malocclusion and OHRQoL. Clinical data were collected and analysed to examine how different malocclusion traits relate to adolescents’ OHRQoL. The PIDAQ instrument was translated, culturally adapted, and evaluated for use in Swedish adolescents. In addition, photograph-based assessment of malocclusion was evaluated by comparison with more comprehensive assessment methods. Finally, registry data were used to investigate sociodemographic differences in orthodontic treatment uptake.

Key conclusions: Malocclusion negatively affects adolescents’ OHRQoL, with poorer OHRQoL reported by females and the most significant impact observed for crowded front teeth. The orthodontic-specific OHRQoL instrument PIDAQ is valid for use in Swedish adolescents. Photographs can be used for reliable malocclusion assessment. Orthodontic treatment uptake within publicly funded care is unevenly distributed across sociodemographic groups, with lower levels observed among males, individuals with a foreign background, and those whose parents have lower educational attainment. The findings may contribute to the development of more effective clinical practices and enhanced strategies for equity within publicly funded orthodontic care.