Study design, sample size, and data collection
This study evaluated 58 children aged between 10 to 12 years referred to a private orthodontic office from 1st November to 30th December 2018 for orthodontic treatments in Shiraz/ Iran. To determine the sample size, we employed G* power statistical power analysis program 3.1.1 . A sample size of 50 was established, using a power of 0.85 and effect size of P = 0.23 for a two-tailed Spearman correlation test (p < 0.05). The sample size was increased to 58 to protect the study from any possible future droppings.
The treatment plan of patients included a removable orthodontic appliance with a midline screw along with a labial bow and Adams or Delta clasps on posterior teeth. Moreover, the inclusion criteria were negative history of orthodontic treatment, absence of maxillofacial syndromes such as cleft lip or palate, and absence of any mental disorders. Patients were instructed to use appliance all around the day except during eating meals, drinking hot liquids, and brushing their teeth, and cleaning their appliance.
The tools employed in this study were GSES, index of orthodontic treatment need-dental health component (IOTN-DHC) and aesthetics component (IOTN-AC), and acceptance of orthodontic appliance questionnaire.
The GSES tool is comprised of 10 items, which are scored according to a 4-point Likert scale. Each item has four answer choices, and the respondents should choose the statement that best describes their condition. The choices include totally opposite to me (score 1), slightly resembles me (score 2), highly resembles me (score 3), and perfectly resembles me (score 4).
This tool is a single-component questionnaire and the scores of the items should be simply summed up to yield the final score. The total score can range from 10 to 40. Higher total scores indicate higher GSE of the individual. In this study, the Persian version of GSES was used. The validity and reliability of the Persian questionnaire have been previously verified .
In IOTN-DHC, the severity of malocclusion is classified into five grades. The higher grades indicate greater need for orthodontic treatment. Accordingly, the orthodontic treatment need can be divided into the following groups including group 1 (no need or slight need for orthodontic treatment; Grades 1 and 2), group 2 (moderate need for orthodontic treatment; Grade 3), group 3 (severe need for orthodontic treatment; Grade 4), and group 4 (very severe need for orthodontic treatment; Grade 5).
In IOTN-AC assessment, 10 images of different dentitions are presented to the patients where they are requested to pick the image with the highest resemblance to their dental status. The images are interpreted as: (1) complete satisfaction or slight dissatisfaction with the appearance of the teeth for images 1-4, (2) moderate satisfaction with the appearance of the teeth for images 5-7, and (3) complete dissatisfaction with the appearance of the teeth for images 8-10.
The acceptance questionnaire was used to assess the acceptance of removable orthodontic appliance by patients. It consisted of 10 incomplete statements, which needed to be completed by patient’s choice. The available answer choices were scored using a 6-point Likert scale. In order to help patients understand the answer items, each answer was accompanied by a matching facial expression (Table 1). Scores 5 to 0 were allocated to the answer choices from left to right. The higher scores indicated higher acceptance and satisfaction with the respective item. The total score of this questionnaire ranged from 0 to 55. A higher total score indicated that the problems of using the removable orthodontic appliance were better accepted by patient and reflected privileged motivation to continue the treatment.
After complete elucidation of the nature of the study and all procedures to the participants, the written consent forms were obtained from the parents before the commencement of the study. Afterwards, the participants filled out GSES and IOTN-AC questionnaires; and IOTN-DHC scores were determined for each patient by researcher [T.BM]. Patients filled out these questionnaires in the absence of their parents. The researcher explained the questions in the questionnaires to the patients and instructed them on how to fill it out.
The removable orthodontic appliance was then delivered to the patients and the first follow-up session was scheduled one month (T1) after delivery. At this session, the patients filled out the acceptance questionnaire for the first time. The acceptance questionnaire was also proposed to the patients three (T2), and six (T3) months after delivery. The data of all questionnaires were collected and underwent statistical analysis.
Data were analyzed using SPSS version 25 using descriptive and inferential statistics. In inferential statistics, the reliability of Persian version of GSES and acceptance questionnaire were evaluated by Cronbach’s alpha test.
According to the result of one-sample Kolmogorov-Smirnov test for normality assessment of variables, Friedman two-way analysis of variance (ANOVA) and Wilcoxon signed rank test were applied to analyze the changes in individual and total scores yielded from acceptance questionnaire at T1, T2, and T3. The Spearman’s rho was calculated to assess the correlation between the GSES scores and IOTN-DHC, IOTN-AC and mean total and individual scores (for the 10 items) of the acceptance questionnaire filled out at T1, T2, and T3.