Cone beam computed tomography volumetric airway changes after orthognathic surgery: a systematic review

The Effects of the Maxillary Movements in Angle Class 2 and 3 Malocclusion Treatment on Nose Air Flow Amount, Rate, and Resistance

Maxillary movements performed during orthognathic surgery affect the external and internal anatomy of the nose. The functional and anatomical effects may change nasal airway parameters after the surgery, and these alterations can be examined objectively by rhinomanometry. In this study, patients who underwent maxillary orthognathic surgery were divided into 3 groups based on their surgical plans: advancement (group 1), impaction and advancement (group 2), and setdown and advancement (group 3). Preoperative and postoperative rhinomanometric data including the average nasal volume, minimum cross-sectional area, average airflow resistance of the right and left nasal passageways, and an average of both nasal passages were collected. The study included 50 patients who underwent orthognathic surgery between October 2021 and October 2022. There were 20 patients each in group 1 and group 2 and 10 patients in group 3. The average nasal passage volume increased in the advancement (group 1) and impaction-advancement (group 2) groups. In addition, the advancement (group 1) group had a decreased average airflow resistance. Setdown-advancement (group 3) group did not show a positive or negative effect on nasal airway parameters. Maxillary movements during orthognathic surgery revealed no adverse effect on nasal parameters. Moreover, advancement and impaction positively affected nasal functional and anatomical parameters.

Three-dimensional assessment of upper airway changes associated with mandibular positional deviations following fibula free flap reconstruction

OBJECTIVES

Fibula free flaps (FFF) are the standard approach to mandibular reconstruction after partial resection, with the goal of restoring aesthetics and masticatory function. The graft position affects both and must be carefully selected. Correlations between sagittal positioning and upper airway anatomy are known from orthognathic surgery. This study aims to evaluate changes in mandibular position and upper airway anatomy after reconstructive surgery with FFF and corresponding correlations.

MATERIALS AND METHODS

Mandibular position after reconstruction was evaluated using three-dimensional datasets of pre- and postoperative computed tomography scans of patients treated between 2020 and 2022. Three-dimensional measurements were performed on both condyles and the symphyseal region. Changes in upper airway volume and minimum cross-sectional area (minCSA) were analysed. Intra-rater reliability was assessed. Correlations between changes in upper airway anatomy and sagittal mandibular position were tested.

RESULTS

The analysis included 35 patients. Intra-rater reliability was good to excellent. Condylar deviations and rotations were mostly rated as small. Changes in symphyseal position were considerably greater. Median airway volume decreased in the oropharynx and hypopharynx. Posterior deviation of the symphysis was associated with a decreasing minCSA in the hypopharynx and vice versa.

CONCLUSIONS

The overall accuracy of mandibular reconstructions with FFF is high, but there is room for optimization. The focus of research should be extended from masticatory to respiratory rehabilitation.

CLINICAL RELEVANCE

Effects on respiratory function should be considered prior to graft positioning. The clinical relevance of upper airway changes within the complex rehabilitation of reconstructive surgery patients needs to be further investigated.

Influencing factors for the development of obstructive sleep apnea after orthognathic surgery in skeletal class III patients: A systematic review

This systematic review aimed to investigate the factors that may contribute to the development of OSA after orthognathic surgery in patients with skeletal class III. Electronic searches of PubMed, Embase, Web of Science, and Cochrane databases were conducted up to December 10, 2022. In total, 277 studies were retrieved and screened according to the inclusion and exclusion criteria, and 14 were finally selected. All studies were of medium quality (moderate risk of bias). The occurrence of OSA after orthognathic surgery in patients with class III skeletal relationships depends on surgical factors and patient self-factors. Surgical factors include surgery type, amount of maxillary and mandibular movement, and the patient's postoperative swelling. Patient self-factors include weight, age, gender, and hypertrophy of the soft palate, tonsils, and tongue. According to information in the 14 selected articles, the incidences of OSA after Le Fort I impaction and BSSO setback, BSSO setback, and Le Fort I advancement and BSSO setback were 19.2%, 8.57%, and 0.7%, respectively, mostly accompanied with greater amounts of mandibular recession. However, no clear evidence exists to confirm that orthognathic surgery is a causative factor for postoperative sleep breathing disorders in patients with mandibular prognathism. The wider upper airway in patients with class III skeletal might be the reason for the rare occurrence of OSA after surgery. In addition, obesity and advanced age may lead to sleep apnea after orthognathic surgery. Obese patients should be advised to lose weight preoperatively.

MSCT 3D Analysis of Nasopharyngeal Airway After Le Fort I Maxillary Setback Surgeries

In recent years, maxillary Le Fort I osteotomy setback has been widely applied in correcting maxilla prognathism. In the meantime, airway considerations have attracted more and more attention. The aim of this research was to observe the alteration of nasopharyngeal airway indexes after maxilla setback and offer evidence for the effectiveness and safety of maxillary Le Fort I setback surgeries. As for a retrospective cross-sectional study, 40 patients diagnosed with maxilla prognathism and undergoing maxillary setback surgeries were enrolled. They were grouped by the type of maxillary setback operations as group A (integral maxillary setback, n=19) and group B (segmental maxillary setback, n=21). Multislice computed tomography data were collected 1 week before (T0) and more than 3 months (T1) after surgery. 3D reconstruction and evaluation of the pharyngeal airway were conducted to analyze nasopharyngeal airway index variation before and after surgery and the difference between group A and group B. Preoperative and postoperative nasopharyngeal airway volume showed no statistical significance in group A (P=0.872) and group B (P=0.169) as well as other indexes of the nasopharynx. The comparison of postoperative airway changes between group A and group B also showed no significant difference. Both integral and segmental maxillary Le Fort I osteotomy setbacks have slight impact on nasopharyngeal airway dimensions and are safe within a specific setback range.

Correlation between polysomnographic parameters and volumetric changes generated by maxillomandibular advancement surgery in patients with obstructive sleep apnea: a fluid dynamics study

STUDY OBJECTIVES

Maxillomandibular advancement surgery (MMA) is a therapeutic option for obstructive sleep apnea (OSA). The main objective of this study was to determine the impact of MMA on the physical and airflow characteristics of the upper airway based on data obtained by computational fluid dynamics (CFD) and to correlate these data with polysomnography parameters. Other objectives included the identification of presurgical variables that could help avoid surgeries likely to have a low success rate.

METHODS

This was a retrospective observational study of 18 patients with moderate-severe OSA who underwent MMA. Polysomnography and computed axial tomography imaging were performed before and after the surgery. Three-dimensional models for CFD study were made based on the images obtained.

RESULTS

MMA achieved an average increase in airway volume of 43.75%, with a mean decrease in the maximum airway velocity of 40.3%. We found significant correlations between improved apnea-hypopnea index values and both the increase in airway volume and decrease in maximum airway speed. Patients with a maximum velocity of less than 7.2 m/s before the intervention had a high rate of surgical failure (43%).

CONCLUSIONS

MMA generates a significant increase in the volume of the upper airway, which was associated with improved flow conditions in the CFD simulation. These findings also correlated with improved polysomnography parameters. Thus, CFD simulation on three-dimensional anatomical models of patients with OSA could contribute to the better selection of candidates for MMA.

CITATION

Furundarena-Padrones L, Cabriada-Nuño V, Brunsó-Casellas J, et al. Correlation between polysomnographic parameters and volumetric changes generated by maxillomandibular advancement surgery in patients with obstructive sleep apnea: a fluid dynamics study. J Clin Sleep Med. 2024;20(3):371-379.

Exploring the relationship between the number of systematic reviews and quality of evidence: an orthognathic surgery-based study

OBJECTIVE

We analyzed the quality and quantity of systematic reviews (SRs) of orthognathic surgery, the most frequently published topic in maxillofacial surgery.

STUDY DESIGN

We searched the PubMed database for SRs of orthognathic surgery with no restriction on the language of publication date. We assessed the certainty of evidence presented according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocol and the Leiden Manifesto using the Grading of Recommendations Assessment, Development, and Evaluation approach. We analyzed the data using descriptive statistics, Pearson´s correlation test, and linear regression.

RESULTS

Of the 171 SRs evaluated, approximately one fifth presented evidence with a high level of certainty. The number of orthognathic surgery SRs has been increasing, and many SRs were published after very similar topics had already been published. There is no relationship between the impact factor and the certainty of evidence.

CONCLUSIONS

An excessive number of SRs of orthognathic surgery are published, and many SRs are superfluous, simply reporting previous findings. Clinicians should not base treatment decisions solely on the evidence presented in SRs, and journal editors and reviewers should evaluate these SRs more critically, particularly when they address topics that have already been covered in the literature.

Do Patients Detect Changes in Breathing After Orthognathic Surgery?

BACKGROUND

Orthognathic surgery addresses facial aesthetics and function in patients with dentofacial deformities. It is associated with changes in upper airway volume (UAV). If changes in UAV are perceived by asymptomatic patients is unclear.

PURPOSE

The purpose was to measure associations between changes in UAV and patient-reported benefits using patient-reported outcome measures.

STUDY DESIGN

A sample presenting dentofacial deformities without reported breathing problems undergoing orthognathic surgery was retrospectively studied. Patients aged 18-30 years with 12-month follow-up were included. Patients with systemic disease, drug abuse, mental health disorder, or temporomandibular joint dysfunction were excluded.

PREDICTOR

The predictor variable was changes in UAV measured in 3-dimensional computed tomography. Subjects were grouped into increased or decreased UAV.

MAIN OUTCOME VARIABLE

The primary outcome variable was changes in health-related quality of life measured with Oral Health Impact Profile 49 (OHIP-49).

COVARIATES

Weight, height, age, sex, and sub-scaled OHIP-49 were registered. Cephalometric measurements of hard tissue movements were recorded.

ANALYSES

Mean, standard deviation, and a level of statistical significance at P < .05 were used. Differences in OHIP-49 were compared using unpaired t-test. The correlation between covariates and outcomes was analyzed using the Spearman's rank test. Analysis of covariance between the predictor and outcome, adjusted for covariates (body mass index), was performed.

RESULTS

Fifty-four subjects with a mean age of 20.89 years and 52% males were enrolled. The mean change in UAV was 0.12 cm3 (standard deviation [SD] 9.21, P = .93) with a mean absolute deviation of 7.28 cm3 (SD 5.54). The mean change in OHIP-49 score was 20.93 (SD 28.90). Twenty-seven (50%) subjects had increased UAV (7.4 cm3, SD 6.13) and the other had decreased (-7.17 cm3, SD 5.01) (P = .01). At follow-up, equal levels of mean OHIP-49 score were found, but because of a baseline difference (15.74, P = .048), the subjects with and without increased UAV improved in OHIP-49 score 13.04 (SD 30.53) and 28.81 (SD 25.33), respectively (P = .04).

CONCLUSIONS

Because equal levels of OHIP-49 score at follow-up, changes in UAV could not be associated with patient-reported health-related quality of life. Patient-reported outcome measure evaluations of orthognathic surgical treatment for airway obstruction should be performed in patients with a perceived impairment.

Current Trends in Orthognathic Surgery

Orthognathic surgery has evolved significantly over the past century. Osteotomies of the midface and mandible are contemporaneously used to perform independent or coordinated movements to address functional and aesthetic problems. Specific advances in the past twenty years include increasing fidelity with computer-assisted planning, the use of patient-specific fixation, expanding indications for management of upper airway obstruction, and shifts in orthodontic-surgical paradigms. This review article serves to highlight the contemporary practice of orthognathic surgery.

Volumetric changes in the upper airway on CBCT after dentofacial orthopedic interventions - a systematic review

OBJECTIVE

To provide a critical overview of the effect of various orthodontic and/or dentofacial orthopedic interventions on three-dimensional volumetric changes in the upper airway.

MATERIALS AND METHODS

Four databases were searched for clinical studies concerning 3D volumetric assessments based on CBCT before and after orthodontics interventions. The quality of the studies was assessed using the quality assessment tool of the National Heart, Lung and Blood Institute. After the use of inclusion and exclusion criteria, the pre-and post-treatment volumes were used to visualize the effect of various orthodontics interventions.

RESULTS

A total of 48 studies were included in this review and none of which were RCTs. The quality of all included studies was assessed as medium. Overall, there is a tendency for an increase in airway volumes after various orthodontic interventions, except for studies concerning extraction therapy with fixed appliances in adults, in which both increases and decreases in airway volumes have been reported.

CONCLUSION

Orthodontic treatment by growth modification and non-extraction therapy with fixed appliances, regardless of the malocclusion, generally showed positive effects on the airway volume. Orthodontic treatment in combination with extractions does not provide an unambiguous insight. A consensus on the methodology of the airway measurement and nomenclature is urgently needed in order to gain insight into the effect of different interventions on three-dimensional airway changes.

CLINICAL RELEVANCE

Various orthodontic treatments do not negatively influence the upper airway volume. However, extraction therapy in adults should be chosen with caution, especially in subjects belonging to a group susceptible to airway obstruction.

Automatic three-dimensional nasal and pharyngeal airway subregions identification via Vision Transformer

OBJECTIVES

Upper airway assessment requires a fully-automated segmentation system for complete or sub-regional identification. This study aimed to develop a novel Deep Learning (DL) model for accurate segmentation of the upper airway and achieve entire and subregional identification.

METHODS

Fifty cone-beam computed tomography (CBCT) scans, including 24,502 slices, were labelled as the ground truth by one orthodontist and two otorhinolaryngologists. A novel model, a lightweight multitask network based on the Swin Transformer and U-Net, was built for automatic segmentation of the entire upper airway and subregions. Segmentation performance was evaluated using Precision, Recall, Dice similarity coefficient (DSC) and Intersection over union (IoU). The clinical implications of the precision errors were quantitatively analysed, and comparisons between the AI model and Dolphin software were conducted.

RESULTS

Our model achieved good performance with a precision of 85.88-94.25%, recall of 93.74-98.44%, DSC of 90.95-96.29%, IoU of 83.68-92.85% in the overall and subregions of three-dimensional (3D) upper airway, and a precision of 91.22-97.51%, recall of 90.70-97.62%, DSC of 90.92-97.55%, and IoU of 83.41-95.29% in the subregions of two-dimensional (2D) crosssections. Discrepancies in volume and area caused by precision errors did not affect clinical outcomes. Both our AI model and the Dolphin software provided clinically acceptable consistency for pharyngeal airway assessments.

CONCLUSION

The novel DL model not only achieved segmentation of the entire upper airway, including the nasal cavity and subregion identification, but also performed exceptionally well, making it well suited for 3D upper airway assessment from the nasal cavity to the hypopharynx, especially for intricate structures.

CLINICAL SIGNIFICANCE

This system provides insights into the aetiology, risk, severity, treatment effect, and prognosis of dentoskeletal deformities and obstructive sleep apnea. It achieves rapid assessment of the entire upper airway and its subregions, making airway management-an integral part of orthodontic treatment, orthognathic surgery, and ENT surgery-easier.