To guide the clinical treatment by comparing the clinical effect, comfort, compliance and effectiveness of MRC myofunctional appliance and traditional tongue function appliances in the treatment of children′s open bite malocclusion.

A total of 12 children (6-11 years, 5 male and 7 female) children with open bite malocclusion at the department of orthodontics of Suzhou Stomatological Hospital were randomly divided into two groups: MRC myofunctional appliance group and traditional tongue spur group. VAS was used to evaluate the wearing comfort; Morisky scale was used to evaluate the patients′ compliance; the treatment time to correct the open bite was recorded respectively to evaluate the clinical treatment efficiency; and the changes of dental arch width were measured by analyzing the model. The t-test was used to evaluate the difference between the two groups.

Both the therapeutic effect of the two groups were effective. The comfort of the group wearing MRC myofunctional appliance was significantly better than that of the traditional tongue spur group, and there was no significant difference in compliance between the two groups. The score of the treatment with MRC myofunctional appliance was (9.9±1.6) months, while the score with traditional tongue spur appliance was (7.2 ± 1.6) months. The variance between the two groups was homogeneous, and the effectiveness of the traditional tongue spur group was slightly better than that of the MRC myofunctional appliance group, with significant difference (sig = 0.790, t = 4.128, P<0.001) . In addition, there was no significant difference in the width of dental arch in the maxillary first molar area before and after treatment in traditional tongue spur group. The width of 53-63 before and after treatment in MRC myofunctional appliance group was (33.0 ± 1.8) and (36.7 ± 2.1) mm, the width of 16-26 was (46.7 ± 1.7) and (48.4 ± 1.9) mm, and the difference was statistically significant (t_cuspid = -5.004, P_cuspid<0.001; t_{first molar} = -5.063, P_{first molar}<0.001) . In a word, the width of anterior and posterior segment of dental arch in MRC myofunctional appliance group increased significantly.

Compared with the traditional tongue spur therapy, the MRC myofunctional appliance group is more comfortable and acceptable. This technique is effective in treatment of openbite. Combined use of the two techniques are recommanded.