Family relationships are complex and dinamic, and inflenced by health conditions, perception and actions of each member. Altered aesthetics of the orofacial area has an effect on the emotions, social contacts, self-esteem and psychological development of the child, and child’s condition affects family activities. Therfore parents with children during the period of change of dentition most often turn to the dentist and orthodontist. The success of treatment during this period largely depends on the child's cooperativeness, which is conditioned by the dynamic processes of growth and psychological development. The factors of treatment success need to be evaluated from biological, biomechanical, psychological and public health aspects. The proposed research continues the ongoing activities of analyzing the psychosocial impact of impaired dental aesthetics which my team dealt with in the project over the previous five-year period. The aim would be to investigate the determinants of treatment demands, the cooperability of children during treatment, and drop-out from treatment, primary orthodontic. Craniodentofacial biometric predictors (dental, skeletal, soft tissues) and psychosocial factors would be analyzed. The role of family and parents/caregivers would be at the forefront. Psychometric, anthropometric, photogrammetric and cephalometric measurements would be used. To examine parents' perceptions of their child's quality of life (oral symptoms, oral functions, aesthetics, psychological and social aspects) and the impact of the child's dentition and occlusion on family relationships, an instrument Parenter/Caregiver perception Questionnaire, that has not been used so far in Croatia would be translated in Croatian (forward and backward translation). Its metric abilities are unknown in Croatian socio-cultural environment. The parents' assessment would be compared to that of the children as assessed by the Child Perception Questionnaire. Family Impact Scale and Early Childhood Oral Health Impact Scale instruments would be also translated and validated to measure parental emotions, family activities, family conflicts, and financial difficulties that may be associated with impaired dental status, malocclusion, dental therapy, and cooperability during therapy. In addition, children and parents would independently assess the degree of satisfaction with their orofacial appearance, the need for therapy, and indicate whether they wanted to be treated. The predictors of seeking, demanding and cooperability will be explored by hierarchical regression analysis and mediation and moderation models. Defining the determinants of patient cooperability during therapy and the success of therapy can provide guidance for directing limited public health system resources to the selection of patients who will benefit most from it.