Comparing study on the hyoid bone position after treatment of class Ⅲ malocclusion using improved appliance FR Ⅲ / 华西口腔医学杂志

<p><b>OBJECTIVE</b>This study aims to compare the changes of hyoid bone position before and after treatment of Angle class Ⅲ malocclusion using improved appliance FR Ⅲ.</p><p><b>METHODS</b>Forty patients with Angle class Ⅲ malocclusion were chosen and divided into two groups, namely, experimental and control. Each group had 20 patients. The young patients in the experi-mental group were treated using improved appliance FR Ⅲ, whereas those in the control group were treated using classic appliance FR Ⅲ. The hyoid bone position of the two groups were comparatively analyzed using an X-ray film before and after treatment.</p><p><b>RESULTS</b>Compared with the condition before treatment, the condition after treatment showed that the hyoid bone position of young patients with Angle class Ⅲ malocclusion treated using improved appliance FR Ⅲ, H-FH, H-S, H-Ptm, and Ar-H-Me exhibited an increased angle (P<0.01), whereas the hyoid bone position of those treated using H-MP and H-Gn showed a decreased angle (P<0.01). The hyoid bone position of young patients with Angle class Ⅲ malocclusion treated using classic appliance FR Ⅲ, H-FH, H-S, and H-Ptm had an increased angle (P<0.05). Moreover, the hyoid bone position of those treated using Ar-H-Me had an increased angle (P<0.01), and the hyoid bone position of those treated using H-MP and H-RGn had a decreased angle (P<0.05).</p><p><b>CONCLUSIONS</b>Compared with the hyoid bone position before treatment, the hyoid bone position after treatment of the young patients with Angle class Ⅲ malocclusion treated using improved appliance FR Ⅲ may move backward and downward, and the mandibular and hyoid bone position may move through clockwise rotation. The mandibular and hyoid bone position of young patients with Angle class Ⅲ malocclusion treated using classic appliance FR Ⅲ obtained a large angle by moving clockwise. The man-dibular bone moves backward and downward, thereby improving the hyoid bone in backward and upward directions. This condition makes a significant difference in treating the hyoid bone position of young patients with functional Angle class Ⅲ malocclusion.
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Retrospective study on change in pharyngeal airway space and hyoid bone position after mandibular setback surgery

OBJECTIVES: The purpose of this study was to evaluate changes in the pharyngeal airway space and hyoid bone position after mandibular setback surgery with bilateral sagittal split ramus osteotomy (BSSRO) and to analyze the correlation between the amount of mandibular setback and the amount of change in pharyngeal airway space or hyoid bone position. MATERIALS AND METHODS: From January 2010 to February 2013, a total of 30 patients who were diagnosed with skeletal class III malocclusion and underwent the same surgery (BSSRO) and fixation method in the Division of Oral and Maxillofacial Surgery, Department of Dentistry at the Ajou University School of Medicine (Suwon, Korea) were included in this study. Lateral cephalograms of the 30 patients were assessed preoperatively (T1), immediately postoperatively (T2), and 6 months postoperatively (T3) to investigate the significance of changes by time and the correlation between the amount of mandibular setback and the amount of change in the airway space and hyoid bone position. RESULTS: Three regions of the nasopharynx, oropharynx, and hypopharynx were measured and only the oropharynx showed a statistically significant decrease (P<0.01). A significant posterior and inferior displacement of the hyoid bone was found 6 months after surgery (P<0.01). Analysis of the correlation between the amount of mandibular setback and the amount of final change in the airway space and hyoid bone position with Pearson's correlation showed no significant correlation. CONCLUSION: In this study, the oropharynx significantly decreased after mandibular setback surgery, and changes in the surrounding structures were identified through posteroinferior movement of the hyoid bone during long-term follow-up. Therefore, postoperative obstructive sleep apnea should be considered in patients who plan to undergo mandibular setback surgery, and necessary modifications to the treatment plan should also be considered.

Changes in hyoid bone position after orthodontic treatment of patients with mandibular deviation / Cambios en la posición del hueso hioides después del tratamiento ortodóntico de pacientes con desviación mandibular

OBJECTIVES: The aim of this study was to observe the influence of orthodontic treatment on the hyoid position of patients with different vertical skeletal craniofacial patterns of mandibular deviations. METHODS: A total of 60 patients with mandibular deviations, including 30 males and 30 females with a mean age of 15.4 years, were recruited. They were equally divided into average angle, high angle, and low angle groups, with a 1:1 gender ratio. Their hyoid position was measured before and after orthodontic treatment. The data were analysed using paired ttests and analysis of variance (ANOVA). RESULTS: After treatment, the hyoid body in the high angle group presented significant forward and upward movements (p = 0.012 and p = 0.005). The hyoid body in the low angle group exhibited significant forward movement (p = 0.048) and a significant increase in the hyoid inclination (p = 0.00). In the average angle group, the hyoid body significantly moved downward (p = 0.031) and the thyrohyoid moved upward (p = 0.046). The ANOVA showed that orthodontic treatment significantly influenced the vertical position and inclination degree of the hyoid (F = 6.37, p = 0.003; F = 6.204, p = 0.004; and F = 3.393, p = 0.025). The average angle group displayed significant differences in these indices compared with the high angle and low angle groups. Orthodontic treatment significantly influenced the mandibular plane angle in the high angle group (p = 0.012). CONCLUSION: Orthodontic treatment influences the hyoid position of patients with different vertical skeletal craniofacial patterns of mandibular deviations by varying degrees.

OBJETIVOS: El objetivo de este estudio fue observar la influencia del tratamiento ortodóntico en la posición hioidea de pacientes con diferentes patrones craneofaciales esqueléticos verticales de desviaciones mandibulares. MÉTODOS: Se reclutaron un total de 60 pacientes con desviaciones mandibulares, incluyendo 30 hombres y 30 mujeres con una edad media de 15.4 años. Los pacientes fueron divididos a partes iguales en grupos de ángulo promedio, ángulo alto, y ángulo bajo, con una proporción de género de 1:1. Su posición hioidea fue medida antes y después del tratamiento ortodóntico. Los datos se analizaron mediante pruebas t pareadas y análisis de varianza (ANOVA). RESULTADOS: Luego del tratamiento, el cuerpo del hioides en el grupo de ángulo alto presentó movimientos significativos hacia adelante y hacia arriba (p= 0.012 y p= 0.005). El cuerpo del hioides en el grupo de bajo ángulo exhibió avance significativo (p = 0.048) y un aumento significativo en la inclinación del hioides (p = 0.00). En el grupo de ángulo promedio, el cuerpo del hioides se movió significativamente hacia abajo (p = 0.031) y el tirohioideo se movió hacia arriba (p = 0.046). El Orthodontic Treatment of Patients with Mandibular Deviation análisis de ANOVA mostró que el tratamiento ortodóntico influye significativamente sobre el grado de inclinación y posición vertical del hioides (F = 6.37, p = 0. 003; F = 6.204, p = 0.004 y F = 3.393, p = 0. 025). El grupo de ángulo promedio mostró diferencias significativas en estos índices en comparación con los grupos de ángulo bajo y ángulo alto. El tratamiento ortodóntico influyó significativamente en el ángulo del plano de la mandíbula en el grupo de alto ángulo (p = 0.012). CONCLUSIÓN: El tratamiento ortodóntico influye en la posición hioidea de pacientes con diferentes patrones craneofaciales esqueléticos verticales de desviaciones mandibulares de diversos grados.

An Investigation of Hyoid Bone Position and Airway Space in Class III Malocclusion after Orthognathic Surgery

A Cephalometric Study on Changes in Pharyngeal Airway Space, Tongue and Hyoid Bone Positions Following the Surgical Correction of Mandibular Prognathism

PURPOSE: This study was aimed at measuring the changes in the hyoid bone position, tongue position, and pharyngeal airway space in subjects with mandibular setback osteotomies. METHODS: Twenty patients were evaluated retrospectively for their changes in pharyngeal airway space, tongue and hyoid bone positions. All patients underwent surgical mandibular setback using bilateral sagittal split osteotomies. The cephalometric analysis was performed preoperatively, and 1 week, 3-6 months, and 1 year postoperatively. RESILT: The hyoid bone moved inferiorly and posteriorly immediately after surgery, and it returned to the preoperative position during follow-up period. The nasopharyngeal airway space was not significantly changed after surgery. A considerable decrease in the oropharyngeal and hypopharyngeal airway spaces following mandibular setback surgery was found. The upper and lower tongue was posteriorly repositioned immediately after surgery. During follow-up period, the hypopharyngeal airway space and lower tongue posture returned to the preoperative positions, but the oropharyngeal airway space and upper tongue posture were not significantly changed. The position of pogonion remarkably changed to backward immediately after surgery, but slightly anterior advancement was found during follow-up period. CONCLUSION: Immediately after mandibular setback surgery, the oropharyngeal and hypopharyngeal airway spaces obviously decreased due to posterior and inferior repositions of the tongue and hyoid bone. During follow-up period, lower tongue and hyoid bone returned to the preoperative positions, it was related to advancement of the pogonion in this period. The narrowing of the oropharyngeal airway space and posterior movement of the upper tongue posture were relatively permanent after mandibular setback surgery. We suspected this phenomenon had an influence on maintaining the total volume of oral cavity against mandibular setback.

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

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.

Evaluation of hyoid bone position and airway size in Class III malocclusion / 대한치과교정학회지

This study was performed to evaluate the hyoid bone position and airway in skeletal class III malocclusion and to prove the correlation between airway, hyoid bone position and mandibular position. The sample, considered of 47 class III malocclusion patients for experimental group and 52 class I malocclusion students for control group. Twenty three linear and angular measurements about hyoid bone position, airway size, mandibular position were taken from the lateral cephalograms. The differences between skeletal class III malocclusion group and normal occlusion group were compared and the correlation were evaluated statistically. The results obtained were as follows, 1. There were significant difference in S-APH, A-APH, N-APH, LAH-PBR, AA-PNS, PNS-ad between class I and class III malocclusion groups. 2. The hyoid bone was more anteriorly positioned in class III malocclusion group than class I malocclusion group and skeletal airway size in class III malocclusion group was smaller than class I malocclusion group. 3. There were significant difference in several measurements especially vertical and angular measurements of hyoid bone position and airway size between male and female. Usually the measurements in male were larger than female. 4. There were no significant correlation between hyoid bone position and airway size also airway size, and didn't showed significant correlation with mandibular position. 5. S-APH showed negative correlation with Wits appraisal and A-APH, N-APH showed positive correlation with Wits appraisal. On the contrary vertical measurements of hyoid bone position showed positive correlation with lower facial height.

A study on positional change of the hyoid bone before and after activator therapy in angle's Class III malocclusion patients / 대한치과교정학회지

This study was conducted to assess the positional changes of hyoid bone following the use of activator in Angles class III malocclusion patients with functional factors. For this study, 40 Angle's class I patients and 40 Angle's class III patients, totally 80 subjects were used. They are all in Hellman's dental age IIIB-IIIC ranges. In lateral cephalogram to compare Angle's class I group and Angle's class III group, and the positional changes of the hyoid bone before and after the use of activator in Angle's class III malocclusion group. The results were obtained as follows; 1. Comparison of Angle's class I group and Angle's class III group. In comparison to Angle's class I group, hyoid bone is more anteriorly and superiorly positioned in Angle's class III group. The hyoid bone showed reverse inclination to the mandibular plane in Angle's class III malocclusion group. 2. Comparison of the hyoid positional change before and after use of Activator in Angle's class III malocclusion group. The hyoid bone is displaced posteriorly and inferiorly in vertical relationship. The hyoid bone also showed counter-clockwise rotation. 3. No statistical difference was found between after Activator use data of Angle's class III malocclusion group and Angle's class I group. It is concluded that the hyoid bone in Angle's class III malocclusion group changed its position, similar to Angle's class I malocclusion group.