Abstract: PURPOSE: To compare the efficacy of tongue appliance combined with chin-cup and facemask in the treatment of anterior crossbite, as well as the effects on the position of hyoid bone and airway, so as to provide reference for clinic. METHODS: Sixty cases with anterior crossbite were selected after treatment, using tongue appliance combined with chin-cup (n=30) and facemask (n=30). Cephalometric radiographs were taken before and after treatment, skeletal, dental, hyoid, and airway space measurements were analyzed with Winceph 9.0 and AutoCAD 2016. SPSS 21.0 software package was used for statistical analysis. RESULTS: Both appliances had a good effect on anterior crossbite. After treatment, SNA, ANS-PNS significantly increased(P<0.05), and SN-MP significantly increased(P<0.05). The upper anterior teeth showed a buccal inclination(P<0.01), the lower anterior teeth had a lingual inclination, and the overjet became normal(P<0.01). UL-E increased in both groups(P<0.05), PLA significantly increased in tongue appliance combined with chin-cup group(P<0.05). H-C3 decreased in both groups(P<0.05), while H-S, H-Ar increased(P<0.01), suggesting that the hyoid bone moved backward and downward. PNS-UPW increased in both groups(P<0.01), and U-MPW increased in facemask group(P<0.01). CONCLUSIONS: Facemask and tongue appliance combined with chin-cup can both promote the development of the maxilla, cause a clockwise rotation of the mandible, and effectively correct the anterior crossbite. Both methods can cause a backward and downward displacement of hyoid bone. Facemask can enlarge the width of nasopharynx and palatopharynx airway, while only the width of nasopharynx can be increased by tongue appliance combined with chin-cup.

Key words: Anterior crossbite, Orthodontic treatment, Tongue appliance, Facemask, Cephalometry