A study on the change of head posture and hyoid bone position before and after rapid maxillary expansions

Bae, Hyeon Cheol; Lee, Jin Woo; Cha, Kyung Suk

Abstract

The present study assessed the effects of Rapid Maxillary Expansion on head posture and hyoid bone position. For this study, 32 Angle's class III patients - hellman 3c ~ adult stage, mean age 12y9m ? were selected divided into two group, A,B according to craniocervical angulation. Craniocervical angulation Increased in Group A and decreased in Group B after the therapy. And 23 Angle's class I persons ~ same hellman stage, mean age 12y7m ~ were selected for the control group. Cephalometric analysis of skeletal pattern, pharyngeal space, head posture, hyoid bone position was performed. The result were as follows, 1. Comparison of skeletal pattern and pharyngeal space 1) All two group(A,B) had Mandibular plane inclined inferiorly and no pharyngeal space change was observed after RME therapy. 2) Skeletal pattern and pharyngeal space of Group A, B were normal before and after treatment. 2. Comparison of head posture 1) Craniocervical angulation of Group A was increased after treatment. That of Group B was decreased and mandibular plane was inclined inferiorly after treatment. 2) Before treatment, craniocervical inclination was normal in Group A but larger than normal in Group B. After treatment, all two groups(A, B) had normal craniocervical angulation. 3. Comparison of hyoid bone position 1) After treatment, long axis of hyoid in Group A, B was not changed. Antero- posteriorly, hyoid position was changed posteriorly in Group A but no change was founded in Group B after treatment. Vertically, hyoid bone position were not changed in two group except increase in APHFH in Group A after treatment. 2) Long axis of hyoid bone was normal in Group A, B before and after treatment. Anteroposteriorly, hyoid bone position was more anterior than Group B, C before treatment but all the position of two groups had normal position after treatment. Vertical position of hyoid bone was normal in all two groups before and after treatment.