To evaluate the oral-health of preschool-children of incarcerated-mothers at nine United Arab Emirates (UAE) prison-nurseries and assess the oral-health knowledge and attitudes of the prison nurseries' caregivers.Cross sectional comparative study.A total of 128 and 254 preschool children formed the study and control groups respectively. All were examined clinically for dental caries using the dmft score and oral health and hygiene status indices. Knowledge and attitudes of all caregivers (n = 45) at prison nurseries were assessed using an interview questionnaire.The prevalence of caries was not significantly different between the two groups with 89.9% [mean-dmft 4.97 (± 3.61)] in the study group and 92.1% [mean-dmft 4.48 (± 3.60)] in the controls. Oral-hygiene in the control group was better with 18.2% having good oral-hygiene compared to 6.2% in the study-group. Oral-health knowledge and attitude of the caregivers of prison nurseries were not satisfactory.Despite the non-significant difference in the caries prevalence between the study and control groups, oral hygiene and care level of vulnerable-children of incarcerated-mothers were significantly poorer. Prisons' caregivers had poor knowledge and attitude of dental health matters.