More than 26,000 children and young people are placed in out-of-home care in Sweden every year. Several studies show that children placed in out of home care have poorer health during childhood and are generally in poorer physical condition later in life. The overall aim of this thesis was to study dental health and dental care in children in out-of-home care (OHC), through registry-based research. Paper I was a registry-based study of dental health care utilisation among young adults who as children had been placed in societal out-of-home care. These young adults had more emergency dental visits and more extractions and fewer regular scheduled dental check-ups than their peers who had never experienced OHC.

Paper II was a systematic review/HTA to evaluate organisational models intended to ensure that children and young people in out-of-home care will receive health and dental care. We were unable to identify any study, of low or medium risk of bias, which examined the effects of organisational models on provision of health and dental care for children and young people in foster care and in institutions.

Papers III and IV were validation studies of the Swedish Quality Registry for Caries and Periodontal Diseases (SKaPa), undertaken to determine the accuracy of the registry and whether it was appropriate for application in the next study (Paper V) and for other research purposes. For dft/DFT, the validation studies showed high agreement between the data in the patient records and the SKaPa registry. However, e/M in deft/DMFT was shown to be uncertain.

Paper V was a registry-based study linking different registries, to investigate dental health and dental care in children in OHC. This study showed that children in OHC have more caries and undergo fewer dental health assessments than those who have never been placed in OHC. There was a difference in dental health examinations before and after the year 2017, with higher frequencies of assessments after the legislative amendment in 2017. However, differences remain.