Three-Dimensional Morphological Changes of the Upper Airway in Patients With Skeletal Class III Malocclusion After Orthognathic Surgery

Quantification of pharyngeal airway space changes after two-jaw orthognathic surgery in skeletal class III patients

BACKGROUND

Skeletal class III malocclusion is a common dentofacial deformity. Orthognathic treatment changes the position of the jaws and affects the shape of the upper airway to some extent. The aim of this study was to use multislice spiral computer tomography data and orthognathic knowledge to quantify the relationship between the amount of surgical movement of the maxilla or mandible in all three spatial planes and the changes in airway volume that occurred.

METHODS

A retrospective study of 50 patients was conducted. Preoperative and postoperative linear changes related to skeletal movements of the maxilla and mandible were measured and compared to changes in the most constricted axial level (MCA) and its anteroposterior (MCA-AP) and transverse diameters (MCA-TV). Correlation tests and linear regression analysis were performed.

RESULTS

Significant interactions were observed between the anterior vertical movement of the maxilla and the MCA-AP. The anteroposterior movement distance of the mandible was significantly correlated with changes in the oropharyngeal, velopharyngeal, total airway volume, MCA, MCA-AP, and MCA-TV. The change in the mandibular plane angle was significantly correlated with the change in velopharyngeal volume, total airway volume (nasopharynx, oropharynx, velopharynx), and MCA. The linear regression model showed that oropharyngeal volume decreased by 350.04 mm³, velopharyngeal volume decreased by 311.50 mm³, total airway volume decreased by 790.46 mm³, MCA decreased by 10.96 mm² and MCA-AP decreased by 0.73 mm² when point B was setback by 1 mm.

CONCLUSIONS

Anteroposterior mandibular control is the key to successful airway management in all patients. This study provides estimates of volume change per millimeter of setback to guide surgeons in treatment planning.

Three-Dimensional Evaluation of Upper Airway Changes After Bimaxillary Surgery of Skeletal Class 3 Patients

The aim of this study was to evaluate the 3-dimensional changes in upper airway space of class 3 patients after surgery with sleep-related breathing disturbance. This is a retrospective cohort study included 25 patients who had undergone bimaxillary orthognathic surgery with maxillary advancement and mandibular setback for skeletal class 3 deformity. The changes in minimum axial area, nasopharyngeal and oropharyngeal airway volume were determined by cone-beam computed tomography images, as well as the sleep parameters by polysomnography preoperatively and postoperatively. The impacts of mandibular setback and maxillary advancement amounts on the airway structures were evaluated and compared with other parameters. The results show that pharyngeal volume measurement means were found to be significantly increased postoperatively ( P <0.05). No significant difference was observed in the mean values of minimum axial area and sleep parameters after the operation ( P> 0.05). A positive relationship was determined between the oropharyngeal volume and minimum axial area changes at a rate of 60% ( r : 0.600). No relationship was revealed between airway volume changes and polysomnographic parameters. An increase in the total airway volume and no postoperative sleep-related disturbance symptoms were observed in the patients treated by maxillary advancement and mandibular setback surgery.

A 3-Dimensional Measurements of Bone and Airway Variables After Le Fort I Distraction Osteogenesis in Patients With Cleft Lip and/or Palate-Induced Midface Hypoplasia: A Retrospective Study

The authors retrospectively analyzed the effects of Le Fort I advancement with distraction osteogenesis on skeletal and airway variables in patients with midfacial hypoplasia induced by cleft lip and/or palate using 3-dimensional computed tomography reconstructions. The authors enrolled 23 subjects with moderate-to-severe midface hypoplasia induced by cleft lip and palate who were treated with Le Fort I distraction osteogenesis (mean age, 19.22±3.48 y; male/female ratio, 20/3); computed tomography images (1 before distraction and another at completion of distraction) were acquired. A 3-dimensional craniometric findings and airway volumes for the nasal cavity, nasopharynx, velopharynx, and upper and lower oropharynx were compared before and after distraction. The relationships between craniofacial morphology and changes in airway volume were also assessed ( P <0.05 was considered significant). Significant increases were observed in airway volumes for the nasal cavity (13.85%), nasopharynx (50.82%), velopharynx (29.57%), and upper oropharynx (36.92%) ( P =0.007, P <0.001, P =0.023, and P <0.001, respectively), whereas no significant changes were observed for the lower oropharynx ( P =0.117). Maxillary horizontal advancement was positively correlated with the airway volumes of the nasopharynx and upper oropharynx after distraction osteogenesis ( rs =+0.451, P =0.031; rs =+0.548, P =0.007); however, no significant correlations were observed for the nasal cavity and velopharynx. The authors' finding indicate that despite rotation of the mandible along with the maxilla, this change does not impact airway volume at the mandibular level. Le Fort I distraction osteogenesis can be feasible for patients with cleft lip and palate-induced midface hypoplasia, with satisfactory appearance and occlusion. Long-term detailed follow-up of the patients postdistraction osteogenesis is warranted.

Is the volume of the maxillary sinus altered after LeFort I orthognathic surgery? A systematic review and meta-analysis

PURPOSE

This systematic review and meta-analysis aimed to investigate anatomical changes in the maxillary sinus after LeFort I osteotomy.

METHODS

The study protocol was developed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols, and it was registered with the International Prospective Register of Systematic Reviews under registration number CRD42021236412.

RESULTS

Our search strategy yielded 64 articles. Of these, 31 were duplicate studies, and 33 were independently reviewed by two authors for eligibility. Of these 33 studies, 24 were excluded as they did not meet the inclusion criteria. Finally, nine studies met the criteria for inclusion, and they were critically reviewed.

CONCLUSION

This systematic review and meta-analysis revealed that maxillary sinus volume decreases after one-piece and multisegment osteotomies in both skeletal class II and class III male and female patients, with one-piece LeFort I osteotomy technique showing a greater reduction in the sinus volume than the multisegment osteotomy technique. The maxillary sinus thickness remained constant postoperatively.

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.

Sequential Changes in Pharyngeal Airway Dimensions After Mandibular Setback Surgery and Its Correlation With Postsurgical Stability in Patients With Mandibular Prognathism

PURPOSE

This study aimed to evaluate the sequential changes in the pharyngeal airway dimensions after mandibular setback surgery and to verify its correlation with postsurgical mandibular stability in patients with mandibular prognathism.

PATIENTS AND METHODS

This retrospective study included 28 patients with mandibular prognathism who underwent surgical orthodontic treatment and isolated mandibular setback surgery. Patients who had cone-beam computed tomography before surgery, immediately after surgery, at short-term follow-up (11.8 ± 5.1 months), and long-term follow-up (43.0 ± 13.1 months) were included. Airway dimensions, including distance, minimum cross-sectional area, and airway volume, were measured to evaluate the changes following mandibular setback surgery. With the measurements of postsurgical mandibular relapse, the relationship between sequential changes in airway dimensions and the mandible was verified using correlation analysis.

RESULTS

Airway dimensions decreased immediately after mandibular setback surgery. The decreased airway dimensions recovered during short-term follow-up and maintained to the long-term follow-up. The mandible was set back 7.7 ± 5.1 mm at pogonion immediately after surgery. Postsurgical skeletal relapse was 1.1 mm at pogonion during short-term follow-up. During long-term follow-up, the mandible moved 0.4 mm anteriorly, which was about 50% of the changes during short-term follow-up. Statistically significant correlations were found between the sequential changes in airway dimensions and the postsurgical skeletal relapse.

CONCLUSION

The decreased airway dimensions following mandibular setback surgery recovered during short-term follow-up and maintained to the long-term follow-up. Dimensional recovery of the pharyngeal airway was correlated with postsurgical skeletal relapse during the 1-year follow-up period.