Patient recruitment
malocclusion
MAY, RECRUITMENT
A preliminary screening was performed of schoolchildren during the period from April 2019 to May 2019. Ten public and private schools were randomly selected from the database of all primary schools in Damascus city, Syria. Intra- and extra-oral clinical examination was performed by the principal investigator (A.H.H.) for 1700 children with an average age of 7 years (range: 6-8 years), including 767 female and 933 male children at the medical clinics of the selected schools. Initially, 90 children with class III malocclusion (52 boys, 43 girls) were expected to be suitable for inclusion in the trial. A formal invitation letter was sent to the parents of candidate children asking them to visit the Department of Orthodontics at the University of Damascus for further analysis and to assess the need for early correction of the deformity. All invited parents came for this in-depth assessment. The following inclusion criteria were used: age between 6 and 8, edge-to-edge incisor relationship or anterior crossbite, class III relationships at the permanent first molars or mesial-step relationships at primary second molars, absence of discrepancy between the centric relation and the maximum intercuspation position, short or normal-face pattern, normal or deep overbite, and no temporomandibular joint disorders or craniofacial anomalies. The radiological inclusion criteria were (1) mild to moderate mandibular prognathism (SNB > 80°, and 0 ≤ANB≥4) and (2) normal or horizontal growth pattern (Bjork’s sum ≤396° ±5°). Fifty seven patients met the inclusion criteria. Information sheets were given to parents of eligible patients. The need for two low-dose CT images, and the possibility of postponing treatment if the child fell into the control group were elaborately explained before taking their written informed consents. Six parents refused to participate in this trial. Therefore the resultant sampling frame included 51 patients. Simple random sampling was used to select 38 patients for this trial who were then assigned randomly to the chin cup and the control groups. The CONSORT flow diagram of patients’ recruitment, follow-up, and entry into data analysis is given in
