Outcomes and assessment schedule for the trial
| Outcome | Time point | Definition | |
| Primary outcome | |||
| Contribution | CMEpost | T1–T0 | △PMW/△IMW×100% |
| Secondary outcomes | |||
| Skeletal and dental changes | △PNW | (T1-T0) & (T2-T0) | / |
| △ANW | (T1-T0) & (T2-T0) | / | |
| △PMW | T1–T0 | / | |
| △AMW | T1–T0 | / | |
| △PAW | (T1-T0) & (T2-T0) | / | |
| △AAW | (T1-T0) & (T2-T0) | / | |
| △IMW | (T1-T0) & (T2-T0) | / | |
| △IPW | (T1-T0) & (T2-T0) | / | |
| BIpost | (T1-T0) & (T2-T0) | (△R_MA +△L_MA)/2 | |
| BIpre | (T1-T0) & (T2-T0) | (△R_PA +△L_PA)/2 | |
| Contribution of skeletal expansion | CNEpost | T1-T0 | △PNW/△IMW×100% |
| CNEpre | T1-T0 | △ANW/△IPW×100% | |
| CMEpre | T1-T0 | △AMW/△IPW×100% | |
| CAEpost | T1-T0 | △PAW/△IMW×100% | |
| CAEpre | T1-T0 | △AAW/△IPW×100% | |
| Recurrence rate of expansion | RNEpost | (T1-T2)/(T1-T0) | △PNW(T2-T1)/△PNW(T1-T0) |
| RNEpre | (T1-T2)/(T1-T0) | △ANW(T2-T1)/△ANW(T1-T0) | |
| RAEpost | (T1-T2)/(T1-T0) | △PAW(T2-T1)/△PAW(T1-T0) | |
| RAEpre | (T1-T2)/(T1-T0) | △AAW(T2-T1)/△AAW(T1-T0) | |
| RME | (T1-T2)/(T1-T0) | △IMW(T2-T1)/△IMW(T1-T0) | |
| RPE | (T1-T2)/(T1-T0) | △IPW(T2-T1)/△IPW(T1-T0) | |
| VAS for pain | From the first postoperative day until T1 | Record every 3 days by patients (VAS score 1–10) | |
| Operative time | Immediately after surgery | Duration of the operation procedure | |
| Treatment costs | T0~T2 | Total cost of surgery, maxillary expansion and examinations. | |
| Safety indicators | |||
| Number of adverse events | Total | T0~T2 | Number of all type of adverse events |
| Specific | Number of each type of adverse events | ||
| Incidence of adverse events | Total | T0~T2 | Number of patients having adverse events / total number of patients×100%. |
| Specific | Number of patients having specific adverse events / total number of patients×100% | ||
‘T1–T0’ represents the value difference between T1 and T0. ‘T2–T0’ represents the value difference between T2 and T0. ‘T0–T2’ represents the duration between T0 and T2. ‘△’ represents the change of the parameter between two time points.