하악전돌증환자에 있어 악교정수술 전후의 두부자세변화에 관한 연구

The change of head posture after orthognathic surgery in mandibular prognathism

According to the functional matrix theory which is one of the many theories on Growth and Development of the craniofacial region, regardless of normal or not, the craniofacial structure of an individual is influenced by a balance between the surrounding skeletal structures including the cranial base, cranial vault, and cervical vertebra and the soft tissues. Head posture may support the equilibration in cranio-cervical region by three musculo-aponeurotic systems which are composed of intracranial aponeurotic system, posterior cervical musculo-aponeurotic system, anterior musculo-aponeurotic system. The facial weight suspending to anterior cranial base is transported to posterior cervical muscles by way of two intracranial dural aponeurotic system and also it is reacted with anterior musculoaponeurotic system continuing to cranial base from abdominal viscera, hyoid bone and mandible anteriorly and thus, equilibration between craniofacial region and cervical region is accomplished by tension of these muscles finally. About the interrelation between head posture and craniofacial morphology, Linder-Aronson have advocated the correlation between the nasopharyngeal airway adequacy and cranio-cervical postural relation, and which is two important biological factor contributing to craniofactial growth. And Solow and others have postulated the interrelationship between craniofacial morphology, airway adequacy and head posture, and he advocated also that hyoid position relates to craniocervical angle and it is contributed to the resting position of mandible and pharynx. Athanausiou et al. have studied the relationship between the change of the position of the hyoid and the pharyngeal depth after orthognathic surgery. Wenzel and Fromm-Lundburg have measured the craniocervical angle postoperatively and compared the altered maxillofacial structure with the change of head position. The author tried-to study the relationship between the craniocervical angle, airway adequacy and the position of the hyoid bone after the alteration of the dentofacial structure through the orthognathic surgery. To study the postoperative relationship, lateral cephalometric analysis was done on 117 normal Korean adults(61 males, 56famales) and 41 patients treated by orthognathic surgery. The following results were obtained : 1. The craniocervical angle of mandibular prognathism group was smaller than the normal group and significantly increased postoperatively. 2. The craniocervical angle showed a significant relationship with the hyoid bone position in both group. 3. The position of the hyoid bone was more anteroinferiorly positioned in the mandibular prognathism group and moved posteriorly after surgery. 4. The change of craniocervical angle was most sensitive to the change of hyoid bone postoperatively. 5. The pharyngeal area showed a positive correlation with the pharyngeal depth. There was no significance between the mandibular prognathism group and the normal group. The mandibular prognathism group showed no difference of pharyngeal area between pre and postoperation. Through the above results, the following conclusion was obtained : In spite of the change of the craniofacial structure postoperatively, the change of craniocervical angle was harmonized to the change of hyoid bone with one unit, maintaining static airway adequacy.