To investigate whether the RW-splint could be used to guide or determine the CR position of the lower jaw so as to provide help for the later diagnostic design.

20 class Ⅱ^Ⅰ malocclusion patients were recruited in orthodontic department of Foshan Stomatological Hospital. They were treated by RW-splint for half a year before orthodontic treatment. The overjet of anterior teeth were recorded before and after treatment.

The overjet of anterior teeth was (6.792 ± 0.795) mm before treatment and (7.720 ± 0.930) mm after half a year's treatment. The overjet of anterior teeth had significant difference (t=6.319, P ＜ 0.01). The overjet change of anterior teeth between before treatment and half year after treatment was (0.928 ± 0.657) mm.

The RW-splint wearing before treatment can be used to guide or determine the mandible in the CR position.

To compare the the rate of en-masse space closure with sliding mechanics between 3M SmartClip self-ligating brackets and 3M Gemini MBT twin brackets in the first premolar extraction patients.

20 Class I malocclusion patients who need first premolar extraction treatment were selected. One arch side of the second premolar and first molar were bonded with 3M self-ligating brackets and the other side bonded with Gemini MBT twin brackets. After leveling and alignment, 0.48 mm × 0.64 mm (0.019 inch × 0.025 inch) stainless steel wire and nickel titanium coil springs were used to close the space. An average rate of space closure per month (mm/month) was calculated in each side.

The median rates of tooth movement for the SmartClip bracket side (1.03 mm per month) and the Gemini MBT twin brackets side (1.00 mm per month) were not significantly different (t = 0.70, P = 0.48).

There was no significant difference in the rate of en-masse space closure between SmartClip brackets and Gemini MBT twin brackets.