Participants, eligibility criteria, and settings
DISEASE, RECRUITMENT
Recruitment for the study started in October 2010 and continued to December 2012. In total, 300 participants who were referred to the Specialist Clinic for Orthodontic Dentistry, Public Dental Service (Mölndal, Sweden) were invited to participate in the study. The study population for the study was patients’ residents to one of nine different Public Dental Service Clinics. Five experienced orthodontists were involved in the orthodontic treatment. Inclusion criteria of the study were age between 12 and 20 years and scheduled for orthodontic treatment of both the upper and lower arches with fixed appliances (MBTTM (McLaughlin, Bennett, Trevisi), pre-adjusted with 0.022-inch slots; 3M Unitek Orthodontic Products, Monrovia, CA, USA) for an expected treatment duration of at least 1 year. The exclusion criteria were treatment with a removable appliance or a lingual fixed appliance and patients with severe disease. Severe disease was defined as patients who, due to their health, were not suitable for general dental care. The patients received information both verbally and in writing regarding the study. After agreeing to participate, each patient signed an informed consent form (or the caregiver signed if the patient was <18 years of age). All the participants lived in communities with a natural fluoride level of < 0.1 mg/L in tap water.