Effect of bilateral sagittal split ramus osteotomy setback on the soft palate and pharyngeal airway space

Validation of a Finite Element Model for Clinical and Virtual Evaluation of the Changes in Airway Dimensions Following Class III Bimaxillary Orthognathic Surgery

Introduction

The aim of this study was to evaluate pharyngeal airway changes in adult skeletal Class III cases whose bimaxillary surgical treatments were planned with different amounts of maxillary and mandibular movement using lateral cephalometric radiographs and finite element analysis (FEA). Our null hypothesis was that bimaxillary orthognathic surgery in which maxillary forward movement (MF) is greater than mandibular backward movement (MB) will result in more expansion of the pharyngeal airway.

Materials and Methods

A total of 31 individuals (11 females, 20 males) with class III skeletal deformity were included in the study. Patients who underwent bimaxillary orthognathic surgery with greater maxillary advancement (MF > MB) were categorized in Group 1 (n = 15), and those with greater mandibular set-back (MB > MF) as Group 2 (n = 16). Changes in airway dimensions were evaluated from lateral cephalometric radiographs. In addition, FEA modeling was used to determine pharyngeal airway changes with 5 different MF/MB combinations performed in skeletal class III bimaxillary surgeries.

Results

Nasopharyngeal and oropharyngeal airway dimensions increased in direct proportion to the amount of MF. Hypopharyngeal volume decreased compared to preoperative value in direct proportion to the decrease in MB. According to the FEA models, total pharyngeal airway volume decreased when MF was less than or equal to MB, was nearly unchanged when MF was 2 mm greater than MB, and increased when MF was 4 mm greater than MB. The results of FEA and lateral cephalometric analysis were compatible.

Conclusion

Our results supported the null hypothesis. We concluded that when possible, planning slightly more maxillary advancement than mandibular set-back will not have an adverse impact on the airway. Although the skeletal deformity only causes forward displacement of the mandible, dividing the skeletal correction between the maxilla and mandible may be considered to avoid the risk to patients' quality of life in terms of respiratory function.

Quantitative changes of upper airway in class III patients undergoing bimaxillary surgery after one-year follow-up: a retrospective study

Background

Bimaxillary surgery is often performed for class III malocclusion, and its complex influence on the upper airway has been well considered. The aim of this research was to provide a scaled formula between upper airway volume changes and bone movements in Class III patients after orthognathic surgery.

Materials and methods

Using a retrospective study design, the investigators enrolled a total of 30 class III malocclusion patients who were undergoing bimaxillary surgery as the study subjects. The subjects included 15 males and 15 females, and their average age was 23.3 ± 3.4 years. CBCT (cone beam tomography) was performed both before and one year after the surgery for each patient. The changes in the soft palate, tongue and upper airway were measured by using CBCT data that was collected before and after surgery. 3D superimposition of CBCT was performed to calculate three-dimensional jaw movements. A multiple regression analysis was used to calculate the quantitative relationship between airway volume changes and jaw movements.

Results

The nasopharynx airway volume was observed to be increased by 1064.0 ± 1336.2 mm³, whereas the retropalatal and retroglossal airway volumes were observed to be decreased by 1399.0 ± 2881.6 mm³ and 1433.8 ± 3043.4 mm³, respectively, after the surgery. One millimetre forward and downward movements of the PNS resulted in increases of 626.90 mm³ and 392.18 mm³ in nasopharynx airway volume, respectively. Moreover, one millimetre retrogression of the B point caused decreases of 314.6 mm³ and 656.6 mm³ in the retropalatal and retroglossal airway volume, respectively. The changes in the soft palate contributed to the decrease in the retropalatal airway volume, whereas the tongue compensated for the decrease in the retroglossal airway volume.

Conclusion

The movements of the PNS and B points could be used to predict upper airway volumetric changes in Class III patients after maxillary advancement and mandibular setback.

Changes in Tongue Area, Pharyngeal Area, and Pharyngeal Airway Velocity after Correction of Mandibular Prognathism

This study aimed to investigate the correlation between the amount of mandibular setback, and the related changes of the tongue area, pharyngeal area, and pharyngeal airflow velocity. Twenty-five patients treated for mandibular prognathism, and serial cephalograms were obtained (T1: preoperation, T2: more than one year postoperation). The postoperative area of the tongue, pharyngeal airway space, and pharyngeal airflow velocity were investigated. Statistical analysis was performed with the Student t-test and Pearson correlation. The amount of mandible setback was significant after surgery (12.8 mm; p < 0.001). The pharyngeal area was significantly reduced 115.5 mm² (p = 0.046). There was a slight reduction of the tongue area (43.2 mm²; p = 0.305) and an increase of pharyngeal airflow velocity (0.3 m/s; p = 0.133). The Pearson correlation coefficient test showed no statistical significance among the amount of horizontal setback and vertical movement of the mandible, such as the reductions in the tongue area, the pharyngeal airway space, and the increase in pharyngeal airflow velocity. Larger amounts of mandibular setback caused a significant reduction of pharyngeal airway area, but without significant changes of the tongue area and pharyngeal airflow velocity.

Evaluation of Changes in the Pharyngeal Airway Space as a Sequele to Mandibular Advancement Surgery: A Cephalometric Study

PURPOSE

To evaluate effect of mandibular advancement on pharyngeal airway space using lateral cephalogram.

MATERIALS AND METHODS

Twenty patients who were diagnosed with class II skeletal malocclusion and underwent surgical intervention for the correction of their dentofacial deformity following orthodontic treatment were included. The soft tissue changes in the pharyngeal space were brought about by the surgical intervention, and the changes that had occurred in increasing the airway were evaluated by using cephalogram.

RESULTS

The results of this study showed that following mandibular advancement surgery, the pharyngeal airway space increased along with an increase in the length and thickness of the uvula with a reduction in the angulation. All the changes remained stable in the late postoperative phase.

CONCLUSION

Patients who underwent mandibular advancement showed a significant increase in the pharyngeal airway space and that remained stable during the evaluation period. As a consequence, mandibular advancement seems to be the most stable surgical movement in relation to airway dimensional gains.

Postoperative Skeletal Stability and Pharyngeal Airway: Counterclockwise versus Clockwise Rotation during Mandibular Setback Surgery

Purpose

To compare the effects of counterclockwise rotation (CCR) and clockwise rotation (CR) of the mandible on the pharyngeal airway during mandibular setback surgery. Materials and Methods. Serial cephalograms of 40 patients with mandibular prognathism, including 20 who underwent CCR and 20 who underwent CR, were taken at the following time intervals: preoperatively (T1), immediately postoperatively (T2), >1 year after surgery (T3), final surgical changes (T31), postoperative stability (T32), and immediate surgical change (T21). Changes in menton (Me) and hyoid (H) positions, soft palate width, soft palate length, soft palate angle and craniovertebral angle (C2C4-SN), and pharyngeal airway spaces (nasal pharyngeal airway (NOP), uvula pharyngeal airway (UOP), tongue pharyngeal airway (TOP), and epiglottis pharyngeal airway (EOP)) were evaluated.

Results

The mean Me (T31) setback for CCR and CR was 12.56 and 13.06 mm, respectively, with 2.41 mm upward and 3.29 mm downward, respectively. The vertical Me position of CR exhibited significant downward movement compared with that of CCR. The mean H setback results for CCR and CR were 4.42 and 5.75 mm, respectively, with 1.47 mm downward and 2.97 mm downward, respectively. The C4C2-SN angles for CCR and CR increased by 2.68° and 3.65°, respectively, whereas their palatal angles increased by 2.35° and 5.25°, respectively. Pearson's correlation analysis (T31) revealed that for CCR, no pharyngeal airway spaces were significantly correlated with any measured variables. In CR, NOP was significantly correlated (r = 0.58) with the vertical Me position. Significant relapse (T32) was observed after CR in the horizontal (r = 0.58) with the vertical Me position. Significant relapse (T32) was observed after CR in the horizontal (r = 0.58) with the vertical Me position. Significant relapse (T32) was observed after CR in the horizontal (

Conclusion

Pharyngeal airway space narrowed postoperatively, and its patency was appropriately maintained through natural physiological regulation of the craniovertebral angle (C2C4-SN). Significant postoperative relapse was correlated with CR.

Change of the upper airway after mandibular setback surgery in patients with mandibular prognathism and anterior open bite

Purpose

It has been reported before that the amount of pharyngeal airway space (PAS) significantly decreases following mandibular setback (MS) surgery in patients with mandibular prognathism (MP). Further, MP patients with an anterior open-bite (AOB) presentation may show a larger decrease in PAS compared with those without AOB. However, studies on postoperative PAS changes in MP patients with AOB remain rare. This study sought to evaluate changes in PAS and hyoid bone positioning following MS surgery in MP patients with and without AOB.

Patients and methods

Twenty patients who underwent two jaw surgery involving MS movement were included. Patients were divided into a non-AOB group (n = 10; overbite > 2 mm) and an AOB group (n = 10; overbite < - 4 mm). Three-dimensional changes in PAS and hyoid bone positioning were compared and statistically evaluated pre- and postoperatively using computed tomography (CT).

Results

The mean magnitude of MS was 6.0 ± 2.8 mm and 5.6 ± 3.2 mm in the non-AOB group and AOB group, respectively. The oropharyngeal volume and upper hypopharyngeal volume were significantly reduced after surgery in both the groups (p = 0.006 and p = 0.003), while the retroglossal cross-sectional area was significantly reduced only in the AOB group (p = 0.028). Although the AOB group showed a larger decrease in PAS, the difference was not statistically significant between the groups. The position of the hyoid bone showed significant posterior and inferior displacement only in the AOB group, while the vertical displacement of the hyoid bone showed a statistically significant difference between the two groups.

Conclusion

PAS was significantly decreased after MS in both the groups, while only the AOB group presented a statistically significant reduction in the retroglossal cross-sectional area. Vertical displacement of the hyoid bone showed a statistically significant difference between the groups, while the PAS change was not. Surgeons should be aware of potential postoperative airway problems that may arise when performing MS surgeries.

3D Airway changes using CBCT in patients following mandibular setback surgery ± maxillary advancement

INTRODUCTION

The aim of this study was to determine the 3D airway changes that occur following mandibular setback surgery alone vs bimaxillary surgery in patients with similar skeletal start forms.

SETTING AND SAMPLE POPULATION

The University of Michigan School of Dentistry and Medical Center. A total of 85 patients undergoing mandibular setback with or without simultaneous maxillary advancement.

MATERIALS AND METHODS

A retrospective evaluation of pre- and post-surgical CBCT scans for patients undergoing mandibular setback surgery alone (14) vs bimaxillary surgery (71) was performed. Cross-sectional evaluation at standardized locations, minimum cross section and volumetric analysis were performed (Dolphin Imaging & Management Solutions).

RESULTS

Patients who underwent mandibular setback surgery alone showed a statistically significant average increase of 47.5 mm² in minimum axial area. Patients who underwent bimaxillary surgery showed a statistically significant increase in airway volume, minimum axial area, location of minimum axial area, and axial area at the retropalatal and retroglossal regions.

CONCLUSIONS

The results demonstrate that the mandible can be setback safely without decreasing airway dimensions. In borderline OSA patients, bimaxillary surgery remains the preferred approach due to the larger airway increases observed. Long-term follow-up with polysomnography must be conducted to determine the full functional implications of both procedures.

Comparison of Pharyngeal Airway between Mandibular Setback Surgery Patients (Skeletal Class III) and Nonsurgery Patients (Skeletal Classes I and II)

Purpose

We investigated the pharyngeal airway dimensions and their correlations in patients who underwent mandibular setback surgery versus those who did not.

Materials and Methods

One hundred and sixty cephalometric radiographs (120 patients) were obtained from patients with three skeletal malocclusion classifications: Class I and Class II in the nonsurgery group and Class III in the surgery group (preoperative and postoperative cephalograms). The following dimensions were measured: nasopharyngeal airway (NOP), uvulopharyngeal airway (UOP), shortest distance from the posterior tongue to the pharyngeal wall (TOP), and distance from the epiglottis to the pharyngeal wall (EOP). Paired t test, one-way analysis of variance, and Pearson correlation coefficients were used for statistical analysis.

Results

Preoperatively, UOP and TOP of skeletal Class III patients (15.2 mm and 16.6 mm) were significantly larger than those of skeletal Class II (11.5 mm and 12 mm) and Class II (12.3 mm and 12.9 mm) patients, respectively. No differences were observed in EOP between the three skeletal patterns. The hyoid bone of Class III patients was significantly anterior to that of Class I/II patients. Furthermore, UOP had a moderate negative correlation with soft palate length. Postoperatively, no significant difference (UOP, TOP, EOP, soft palate width, and hyoid bone) was found between the skeletal classes.

Conclusion

Preoperatively, UOP and TOP of skeletal Class III patients were significantly wider than those of skeletal Class I/II patients. Pre- and postoperatively, EOP did not exhibit significant differences among the three skeletal classifications. No differences were found in all postoperative pharyngeal airway dimensions between Class III patients and nonsurgery patients (Class I and Class II).

Volumetric changes of the upper airway following maxillary and mandibular advancement using cone beam computed tomography

The objective of this project was to retrospectively evaluate changes in volume of different compartments of the upper airway in response to maxillary, mandibular, and bimaxillary advancement surgeries and to predict the extent of volumetric changes associated with these surgical movements. Pre- and post-surgical cone beam computed tomography scans of 36 patients were evaluated for changes in nasal cavity, nasopharyngeal, oropharyngeal, and hypopharyngeal compartments. The amount of movement for each surgery was measured from skeletal landmarks to reference planes and was correlated with volumetric changes. Maxillary advancement of 4.0±2.2mm increased the oropharyngeal volume significantly (41.40%), and mandibular advancement of 3.8±1.6mm also significantly increased the oropharyngeal volume (21.17%). Bimaxillary advancement of 5.1±1.3mm for the maxilla and 6.4±3.1mm for the mandible significantly increased nasopharyngeal (27.45%), oropharyngeal (66.39%), and hypopharyngeal (52.48%) volumes. Furthermore, for every millimeter anterior movement, oropharyngeal volume increased by 2319.2±771.8mm³. Bimaxillary advancement showed a greater increase than isolated maxillary and mandibular advancement in all pharyngeal compartments. Every millimeter of advancement in the bimaxillary group led to a significant increase in oropharyngeal volume, while every millimeter downward movement showed a significant increase in nasopharyngeal volume.

Computational fluid dynamics study of the pharyngeal airway space before and after mandibular setback surgery in patients with mandibular prognathism

The purpose of this study was to investigate the relationship between the pressure drop in the pharyngeal airway space (ΔP_PAS) and the minimum cross-sectional area (minCSA) of the pharyngeal airway before and after mandibular setback surgery using computational fluid dynamics, in order to prevent iatrogenic obstructive sleep apnoea. Eleven patients with mandibular prognathism underwent bilateral sagittal split osteotomy for mandibular setback. Three-dimensional models of the upper airway were reconstructed from preoperative and postoperative computed tomography images, and simulations were performed using computational fluid dynamics. ΔP_PAS and the minCSA of the pharyngeal airway were calculated, and the relationship between them was evaluated by non-linear regression analysis. In all cases, the minCSA was found at the level of the velopharynx. After surgery, ΔP_PAS increased significantly and the minCSA decreased significantly. The non-linear regression equation expressing the relationship between these variables was ΔP_PAS=3.73×minCSA^-2.06. When the minCSA was <1cm², ΔP_PAS increased greatly. The results of this study suggest that surgeons should consider bimaxillary orthognathic surgery rather than mandibular setback surgery to prevent the development of iatrogenic obstructive sleep apnoea when correcting a skeletal class III malocclusion.

Cone-beam computed tomography evaluation of the maxillofacial features of patients with unilateral temporomandibular joint ankylosis undergoing condylar reconstruction with an autogenous coronoid process graft

Objective

To evaluate the changes in the jaws and the upper airways of unilateral temporomandibular joint ankylosis patients who underwent condylar reconstruction via autogenous coronoid process grafts using cone-beam computed tomography (CBCT).

Study design

The 27 included patients underwent CBCT examinations at three stages: T0 (within two weeks before surgery), T1 (two weeks after surgery), and T2 (an average of 13 months after surgery). Forty items related to the maxillofacial hard tissues and the upper airway collected at the three times and the coronoid process graft volumes after surgery were compared.

Results

Some integral items related to the mandibular hard tissues exhibited statistical difference shortly after surgery. Some integral items related to maxillofacial hard tissues changing obviously long period after surgery may result from graft remodeling. Asymmetry-related item regarding local neo-condyle and some airway items were significantly different between T0 and T1. Due to variations in graft remodeling, some related local asymmetry items and airway items differed significantly between T0 and T2.

Conclusions

Anteriorly and inferiorly located neo-condyles and a trend toward the pronation of the mandible were observed and the narrowness of the upper airway was improved shortly after surgery. The grafts remodeled differently and some integral and asymmetry items related to neo-condyle changed. The improvements in the upper airway were slightly reduced.

Surgical Maxillary Advancement Increases Upper Airway Volume in Skeletal Class III Patients: A Cone Beam Computed Tomography-Based Study

STUDY OBJECTIVES

Although volumetric changes of the upper airway occur following surgical advancement of the maxilla, few studies investigated these changes using three-dimensional imaging techniques. Thus, the goal of this study was to verify whether the surgical advancement of the maxilla affects the volume of the upper airway and to determine any association of these volume changes with sex and age.

METHODS

Preoperative and postoperative cone-beam computed tomography (CBCT) scans of 14 patients (8 male and 6 female) who underwent maxillary advancement to correct skeletal class III deformities were assessed to determine the postoperative volumetric changes in the upper airway. Preoperative and postoperative airway volume measurements were compared by means of paired t-test, which was also used to compare airway volume between genders. Pearson correlation coefficient was used to verify whether a correlation between age and upper airway volume was present.

RESULTS

Maxillary advancement produced significant upper airway volume increases (mean 20.94%, p < 0.05) on nearly half of our sample. However, sex and age did not seem to influence upper airway volume in our sample of skeletal class III patients.

CONCLUSIONS

Surgical advancement of the maxilla may produce significant volume increases in the upper airway of skeletal class III patients regardless of sex and age.

Sleep-disordered breathing following mandibular setback: a systematic review of the literature

INTRODUCTION

A mandibular setback reduces space in the pharyngeal airway, and it has been suggested that it might induce sleep-disordered breathing.

OBJECTIVES

An evidence-based literature review was conducted to identify the effect of mandibular setback on the respiratory function during sleep.

METHODS

The authors performed a systematic review of pertinent literature published up to 2014. A structured search of literature was performed, with predefined criteria. A survey of the PubMed, ScienceDirect, and Cochrane database was performed. A manual search of oral and maxillofacial surgery-related journals was accomplished. Potentially relevant studies then had their full-text publication reviewed.

RESULTS

A total of 1,780 publications were evaluated, through which nine papers (seven case series and two case-control studies) were selected for the final review. No evidence of sleep disorder after six months was related in 223 patients. In one study, two patients developed obstructive sleep apnea syndrome after surgery, and in another two studies, seven patients presented an increase of obstructive apneas/hypopneas events and oxygen desaturation index. Most of the patients analyzed were young and thin.

CONCLUSION

There was no evidence of postoperative sleep apnea syndrome after a mandibular setback surgery. However, one should always consider a potential reduction of the upper airway space during the treatment plan. Obese patients and those submitted to large amounts of mandibular setbacks present a higher chance to develop obstructive sleep apnea syndrome.

The "Rubber Band" and "Slingshot" Effects of the Posterior Airway Space in Mandibular Orthognathic Surgeries

INTRODUCTION

Mandibular surgeries are the most common orthognathic procedures that are undertaken. The pharyngeal airway space (PAS) is influenced by the changes in the sagittal changes of the mandible. Mandibular advancement surgeries are used to an advantage in obstructive sleep apnea cases to improve the airway space. On the contrary, there can be a considerable decrease in the airway space during mandibular setback procedures. Numerous studies have been conducted to study the effect of changes in the PAS during mandibular procedures. However, a combined radiographic and endoscopic analysis of the airway space has been sparsely done in recent literature.

MATERIALS AND METHODS

Thirty-one patients with mandibular discrepancies who needed mandibular surgeries were chosen. The assessment of PAS was done using both lateral cephalograms and endoscopic examination.

RESULTS

As lateral cephalograms can study only the two-dimensional changes in the PAS, endoscopic examination both pre operatively and post operatively enabled the exact assessment of mandibular surgeries on the PAS. The PAS responds to setback mandibular surgery by modifying itself- called the "Rubber band" effect and in advancement surgeries as "Slingshot effect".

Effects of Le Fort I Osteotomy on the Nasopharyngeal Airway-6-Month Follow-Up

PURPOSE

The literature discussing the impact of a single Le Fort I osteotomy on nasopharyngeal airways is limited. This study assessed the volumetric changes in the nasopharyngeal airway after a single Le Fort I osteotomy and explored the correlation between these changes and 3-dimensional surgical movements of the upper jaw.

MATERIALS AND METHODS

This retrospective study was conducted in 40 patients who had undergone a single Le Fort I (maxillary advancement with or without impaction) to correct Class III malocclusion with maxillary hypoplasia. Preoperative (T1) and 6-month postoperative (T2) cone-beam computed tomographic (CBCT) scans of these patients were used for analysis. Maxillary surgical movements and volumetric changes in the nasopharyngeal airway were measured. The reproducibility of the measurements was evaluated using paired t tests and intraclass correlation coefficients. The Wilcoxon test and Pearson correlation coefficient were applied to evaluate the volumetric changes in the nasopharyngeal airway space and assess the correlations of these changes to the maxillary surgical movements.

RESULTS

Six patients were excluded from the study owing to major differences (>5°) in their head and neck posture between the T1 and T2 CBCT scans. The errors of the repeated measurements were insignificant (P > .05), with a high level of agreement (r = 0.99; P < .05) between the repeated digitization of the landmarks. There was a statistically significant impact of a Le Fort I osteotomy on the right maxillary sinus (decreased by 17.8%) and the lower retropalatal space (expanded by 17.3%; P < .05). The correlation between the change in airway volume and the magnitude of surgical maxillary movements was moderate (r = .4). Similarly, there was a moderate correlation between changes in the upper nasopharynx and those in the hypopharynx.

CONCLUSION

The single Le Fort I osteotomy was found to increase the retroglossal airway volume. This could be important for the treatment of obstructive sleep apnea in patients with maxillary deficiency. A long-term follow-up assessment of a larger sample with a functional assessment of airway would be beneficial to confirm these findings.

Correlation between the Pharyngeal Airway Space and Head Posture after Surgery for Mandibular Prognathism

Purpose. The aim of this study was to determine the correlation between the pharyngeal airway space and head posture after mandibular setback surgery for mandibular prognathism. Materials and Methods. Serial lateral cephalograms of 37 patients with mandibular prognathism who underwent intraoral vertical ramus osteotomy (IVRO) were evaluated before (T1) and immediately (T2), between 6 weeks and 3 months (T3), and more than 1 year (T4) after surgery. Paired t-tests and Pearson's correlation analysis were used to evaluate the postoperative changes in all cephalometric parameters, including the mandible, hyoid, head posture (craniocervical angle), and pharyngeal airway space. Results. The mandible and hyoid were set back by 12.8 mm and 4.9 mm, respectively, at T2. Furthermore, the hyoid showed significant inferior movement of 10.7 mm, with an 8 mm increase in the tongue depth. The upper oropharyngeal airway (UOP) shortened by 4.1 mm, the lower oropharyngeal airway (LOP) by 1.7 mm, and the laryngopharyngeal airway by 2 mm. The craniocervical angle showed a significant increase of 2.8°. UOP and LOP showed a significant correlation with the craniocervical angle at T2 and T4. Conclusions. Our findings conclude that the oropharyngeal airway space is significantly decreased and correlated with a change in the head posture after mandibular setback surgery.

Soft tissue response after Class III bimaxillary surgery

OBJECTIVE

To analyze the impact of surgical change in anterior face height and skeletal relapse on the long-term soft tissue profile.

MATERIALS AND METHODS

Cephalometric radiographs of 81 patients taken before surgery and at five time points during a 3-year follow-up period were analyzed. All patients had Le Fort I and bilateral sagittal split osteotomies. The patients were divided into three subgroups according to the change in anterior face height during surgery. Calculations of soft to hard tissue ratios were based on the long-term soft tissue response relative to the surgical repositioning.

RESULTS

The horizontal surgical repositioning varied considerably, depending on whether anterior face height was increased or decreased. For upper lip prominence, the pattern of long-term change was the same irrespective of change in face height. In all groups, upper lip thickness decreased in both the short term and the long term, particularly in patients with surgical increase in face height. Lower lip thickness increased in the short term but decreased during the follow-up period. There were significant associations between horizontal soft tissue and corresponding hard tissue changes, except for soft tissue A-point and upper lip, when face height was increased. The ratios were higher for mandibular variables than for maxillary variables, particularly for B-point and pogonion when anterior face height had decreased.

CONCLUSION

A change in facial height influences the soft tissue response. The mandibular soft tissues closely follow skeletal relapse beyond 2 months postsurgery. The findings have clinical implications for the relative maxillary and mandibular repositioning when planning surgery.

Dimensional changes of maxillary sinuses and pharyngeal airway in Class III patients undergoing bimaxillary orthognathic surgery

OBJECTIVE

To evaluate the pharyngeal airway and maxillary sinus volume changes after mandibular setback surgery combined with maxillary advancement and/or impaction surgery.

MATERIALS AND METHODS

Seventeen Class III skeletal patients (11 females, 6 males) who required bimaxillary orthognathic surgery were selected. Volumetric measurements were performed using cone beam computed tomography (CBCT) scans preoperatively and 3.9 ± 0.87 months postoperatively. All the CBCT scans were assessed and analyzed using MIMICS 14.0 software. Preoperative and postoperative volumes of pharyngeal airway and maxillary sinuses and the relationship between the amounts of surgical movement of the jaws and the above volumes were statistically evaluated.

RESULTS

The pharyngeal airway area presented no significant change except for the lower and total pharyngeal airway volumes in males, in whom a significant decrease was observed (4196.27 ± 2061.11 mm(3) and 3375.53 ± 3624.67 mm(3), respectively). No significant change was observed in the minimal cross-sectional area of the pharyngeal airway. There was a significant decrease in the volume of the maxillary sinuses after the surgery by 3448.09 ± 3315.56 mm(3). No correlation was found between the amount of skeletal movement and the change in the volume of pharyngeal airway or maxillary sinuses.

CONCLUSION

There was a significant decrease only for lower and total pharyngeal airway volumes in males and a significant decrease in the volume of the maxillary sinuses.

Effects of orthognathic surgery on oropharyngeal airway: a meta-analysis

Oropharyngeal changes caused by orthognathic surgery have been a concern because the sleep quality of patients may be enhanced or worsened by these changes. The purpose of this meta-analysis was to identify, review and compare scientific literature about changes in airway in adult patients undergoing orthognathic surgery to correct anteroposterior osseous discrepancies. An electronic search of four databases was carried out up to July 2010, with supplemental hand searching of the references of the retrieved articles. Quality assessment of the included articles was carried out. Data were extracted and a meta-analysis was performed. Heterogeneity was assessed amongst the studies and results were presented in forest plots. 49 studies met the inclusion criteria. Only studies with moderate or high methodological soundness were included in the review. Moderate evidence was found to support a significant decrease in the oropharyngeal airway in mandibular setback surgery, a milder decrease in bimaxillary surgery to correct Class III and an increase in maxillomandibular advancement surgery. Evidence is lacking on airway volume changes after orthognathic surgery.

Comparison of pharyngeal airway changes on plain radiography and cone-beam computed tomography after orthognathic surgery

PURPOSE

The purpose of the present prospective study was to develop a 3-dimensional analysis of the airway using cone-beam computed tomography (CBCT) and to determine whether changes in the airway before and after orthognathic surgery correlate on 2-dimensional lateral cephalogram and 3-dimensional CBCT images.

MATERIALS AND METHODS

Patients requiring orthognathic surgery during 2004 to 2005 were recruited for the present study. Lateral cephalograms and CBCT scans were obtained at 3 points: preoperatively, within 1 month postoperatively, and after 6 months postoperatively. The nasopharynx, oropharynx, and hypopharynx were segmented on both the radiograph and the CBCT scan for each patient in a repeatable manner at each point. For the lateral cephalogram, linear measurements in the middle of each of the 3 segments were obtained. For the CBCT, volumetric measurements of each of the 3 segments were obtained. The intrarater variability was assessed, and Pearson's correlation was used to compare the 2 imaging modalities.

RESULTS

A total of 20 patients scheduled for orthognathic surgery were recruited for the present study. Of the 20 patients, 13 were female and 7 were male. The mean age at surgery was 23.85 years (range 14 to 43). Of the 20 patients, 6 underwent maxillary advancement only, 8 underwent mandibular advancement with or without genioplasty, and 6 underwent 2-jaw surgery or mandibular setback. We examined the entire cohort without separation into procedure or examination point and found a weak, but statistically significant, correlation between the linear and volume measurements in the nasopharyngeal and oropharyngeal regions but not in the hypopharyngeal region (r = 0.43, P < .002; r = 0.49, P < .0002; r = 0.16, P = .26, respectively). The maxillary advancement group (n = 6) demonstrated a correlation between the linear and volume measurements in the nasopharyngeal region (r = 0.53, P = .03). The mandibular advancement with or without genioplasty group (n = 8) showed a correlation in the nasopharyngeal and oropharyngeal regions (r = 0.55, P < .02, and r = 0.46, P = .05, respectively). For the combination/setback procedures (n = 6), a correlation was found in the oropharyngeal region (r = 0.64, P < .01). All other comparisons between the linear and volume measurements did not correlate. Additionally, no correlations were found between the linear and volumetric change in airway size between 6 months postoperatively and preoperatively, except for the oropharyngeal region (r = 0.67, P < .01).

CONCLUSION

We present a method of measuring the airway that could be used for both 2-dimensional and 3-dimensional images. It includes segmentation of the pharyngeal airway into its nasopharyngeal, oropharyngeal, and hypopharyngeal components. Correlations were found between the linear and volumetric measurements of the segmented airway in patients who had undergone orthognathic surgery; however, the correlations were generally weak.

Changes in the pharyngeal airway space and hyoid bone position after mandibular setback surgery for skeletal Class III jaw deformity in Japanese women

INTRODUCTION

The purpose of the study was to examine the changes in stability of pharyngeal airway space (PAS) and hyoid bone position after 2 types of mandibular osteotomies in comparison with a control group.

METHODS

The subjects included 46 Japanese women with skeletal Class III malocclusion. Twenty-five patients with mandibular prognathism underwent single-jaw surgery with bilateral sagittal split ramus osteotomy (SSRO), and 21 patients underwent bilateral intraoral vertical ramus osteotomy (IVRO). The control subjects included 30 volunteer women with normal occlusion. The treated subjects were assessed at the beginning of treatment, immediately after surgery, and after postsurgical treatment.

RESULTS

The Class III subjects had a significantly wider PAS than did the control subjects. Significant decreases in the lower PAS were observed after orthognathic surgery. The hyoid bone showed upward and forward movement with upward movement of the lower border of the PAS during the postsurgical stage in the SSRO group. In contrast, the anterior border of the PAS and the hyoid bone showed considerable backward movement in the IVRO group.

CONCLUSIONS

The posttreatment morphology of the PAS in both Class III groups approached that of the control group. The IVRO group showed a reduction in the airway dimensions, especially during the postsurgical period, which occurred during surgery in the SSRO group.

Sagittal mandibular development effects on the dimensions of the awake pharyngeal airway passage

OBJECTIVE

To test the hypothesis that sagittal mandibular development has no effects on the dimensions of the awake pharyngeal airway passage.

MATERIALS AND METHODS

Ninety-one subjects (age 15-25 years) with a normal vertical growth pattern of the mandible, normally positioned maxilla, and various sagittal mandibular developments were divided into three groups based on the sagittal mandibular development. Group I included 37 subjects who had a normally positioned mandible (76 degrees < or = angle between 'S,' 'N,' and 'B'; it represents the antero-posterior position of the maxilla in relation to the anterior cranial base [SNB] < or = 82 degrees ), Group II included 31 subjects in whom the mandible was retrognathic (SNB < 76 degrees ), and Group III included 23 subjects in whom the mandible was prognathic (SNB > 82 degrees ) in relation to the anterior cranial base. Lateral cephalograms were traced manually to evaluate the pharyngeal airway passage.

RESULTS

The length of the soft palate was significantly smaller in mandibular prognathism subjects than in subjects with mandibular retrognathism (P < .01). The thickness of the soft palate was significantly greater among subjects with mandibular prognathism than in subjects with normal (P < .01) and retrognathic (P < .001) mandibular development. The sagittal mandibular development had no effect on the dimensions of the nasopharyngeal and hypopharyngeal airway passage. The depth of the oropharynx was comparable among the subjects with normal and retrognathic mandibles but was greater (P < .001) among subjects with mandibular prognathism.

CONCLUSIONS

The hypothesis is rejected. Sagittal mandibular development had significant effects on the dimensions of the awake pharyngeal airway passage.

Mandibular distraction osteogenesis for pediatric airway management. J Oral Maxillofac Surg. 2010;68:1512-1523. [PMID: 20417010 DOI: 10.1016/j.joms.2009.09.099]

PURPOSE

Mandibular retrognathia may cause upper airway obstruction in the pediatric patient due to tongue collapse and physical obstruction in the hypopharyngeal region. Mandibular distraction osteogenesis (DO) may be a useful treatment option to avoid tracheostomy. This study reviews 35 patients who underwent DO as treatment for concomitant jaw discrepancy and corrective airway management.

PATIENTS AND METHODS

Thirty-five consecutive patients, 20 male and 15 female, with airway obstruction were evaluated retrospectively using clinic and hospital records. The mean age was 3.5 months (range, 36 weeks' gestation to 4 years). The group consisted of patients with Pierre Robin sequence, Stickler syndrome, Opitz's syndrome, Down syndrome with obstructive sleep apnea, Goldenhar's syndrome, Treacher Collins syndrome, and mandibular retrognathia. All patients had obstruction limited to the upper airway related to severe retrognathia and posterior tongue-base displacement confirmed with direct laryngoscopy. All patients underwent mandibular DO to avoid or remove a tracheostomy and allow development of speech and normal feeding. Each patient underwent bilateral mandibular corticotomies and placement of 2 percutaneous Kirchner wires and extraoral distraction devices. Following a 0-day latency, DO was performed at 3 to 5 mm per day (mean: 4 mm per day) for a mean total of 22.5 mm (range, 15-32 mm). The mean consolidation period was 28 days (range, 20-42 days). Preoperative radiographs (lateral cephalometric radiograph and/or CT scan) were obtained in all cases preoperatively and at least 3 months postoperatively for analysis.

RESULTS

All patients experienced resolution of obstructive upper airway symptoms during the DO process. No patient required tracheostomy, and pre-existing tracheostomy devices were decannulated before DO completion. Apnea monitors failed to trigger in any patient postdistraction, and sleep studies were normal. The mean follow-up period was 9 months (range, 4-18 months). Radiographic analysis revealed the mean increase in posterior airway space was 12 mm. The mean decrease in overjet was 12 mm. Mandibular length increased a mean of 15 mm, and the sella-nasion-B point angle increased a mean of 16 degrees. DO complications included premature consolidation requiring manual refracture, hypertrophic scarring, device replacement, apertognathia with resolution within 8 to 12 weeks following device removal, and intraoral pin exposure. There were no cases of pin site infections or development of temporomandibular ankylosis.

CONCLUSION

Mandibular distraction osteogenesis is a viable option for the pediatric patient with upper airway obstruction due to mandibular deficiency to avoid a tracheostomy or other surgical intervention. Mandibular DO treats the etiology of the disease process and may allow for future growth.