Three-dimensional analysis of the pharyngeal airway space and hyoid bone position after orthognathic surgery

Postsurgical Volumetric Airway Changes in Class III Patients Receiving Bimaxillary Orthognathic Surgery

The purpose of the present study was to investigate the pharyngeal airway space (PAS) changes in class III patients receiving bimaxillary orthognathic surgery and correlate the PAS volume and minimum axial section changes with the magnitude of the surgical movement. This research involved a retrospective sample composed of 38 patients with class III skeletal occlusions. Three-dimensional measurements of the PAS volume and minimum axial section were conducted. Cephalometric points were used to verify the extent of jaw-hyoid bone movement. No significant differences were found between pre and postoperative total PAS volume (P = 0.280), nasopharyngeal volume (P = 0.545), oropharyngeal volume (P = 0.297), and minimum axial section (P = 0.568). Anterior movement of point A and posterior nasal spine were significantly associated with an increase in total PAS volume, oropharyngeal volume, and minimum axial section (P < 0.05). However, the posterior movement of menton was significantly associated with a decrease in total PAS volume, oropharyngeal volume, and minimum axial section (P < 0.05). The results of the present study indicated that PAS is not negatively affected by bimaxillary surgery in class III patients. However, the planning of class III patients who are prone to the development of airway problems should be done carefully.

Three-Dimensional Assessment of Upper Airway Volume and Morphology in Patients with Different Sagittal Skeletal Patterns

BACKGROUND

The relationship between respiratory function and craniofacial morphology has garnered significant attention due to its implications for upper airway and stomatognathic development. Nasal breathing plays a key role in craniofacial growth and dental positioning. This study investigated upper airway morphology and volume differences among individuals with class I, II, and III skeletal anomalies.

METHODS

Ninety orthodontic patients' CBCT scans were analyzed to assess the oropharynx and hypopharynx volumes. Skeletal diagnosis was established based on the cephalometric analysis.

RESULTS

A significant volume change in the oropharynx and pharynx was demonstrated when comparing class II with class III anomalies (p = 0.0414, p = 0.0313). The total volume of the pharynx was increased in class III anomalies. The area of the narrowest part of the pharynx (MIN-CSA) significantly decreased in classes I and II compared to class III (p = 0.0289, p = 0.0003). Patients with Angle class III anomalies exhibited higher values in the narrowest pharyngeal segment. Gender differences were significant in pharyngeal volumes and morphologies across malocclusion classes.

CONCLUSIONS

The narrowest segment of the pharynx had the highest values in patients with Angle class III. The volume of the oropharynx was found to be greater in patients with Angle class III versus patients with Angle class II.

Airway changes in patients with unilateral cleft lip/palate (UCL/P) after maxillary advancement

OBJECTIVES

To assess the effect on the retropalatal airway (RPA), retroglossal airway (RGA), and total airway (TA) volumes and cephalometrics (SNA, SNB, ANB, PP-SN, Occl-SN, N-A, A-TVL, B-TVL) after maxillary advancement orthognathic surgery in patients with unilateral cleft lip/palate (UCL/P) using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

The CBCT scans of 30 patients (13 males and 17 females, 17-20 years old) with UCL/P were evaluated at two time points: preoperative (T1) and postoperative (T2). The interval between T1 and T2 ranged from 9-14 weeks, except for two patients in whom the interval was 24 weeks. Intraexaminer reliability was measured with an intraclass correlation coefficient test. A paired t-test was used to compare the airway and cephalometric measurements between T1 and T2, with a P value of .05 being considered significant.

RESULTS

From T1 to T2, significant increases were found in the volumes of RPA (from 9574 ± 4573 to 10,472 ± 4767, P = .019), RGA (from 9736 ± 5314 to 11,358 ± 6588, P = .019), and TA (from 19,121 ± 8480 to 21,750 ± 10,078, P = .002). In addition, the RGA (from 385 ± 134 to 427 ± 165, P = .020) and TA (from 730 ± 213 to 772 ± 238, P = .016) sagittal area increased significantly. For minimal cross-sectional area (MCA), only the RPA increased significantly (from 173 ± 115 to 272 ± 129, P = .002). All cephalometric changes were statistically significant between T1 and T2 except for SNB.

CONCLUSIONS

Maxillary advancement in patients with UCL/P produces statistically significant increases in the retropalatal (volumetric and MCA), retroglossal (volumetric and sagittal), and total (volumetric and sagittal) airways based on data from CBCT imaging.

Causes of Reoperation Consultation and Clinical Review of Actual Reoperation After Previous Orthognathic Surgery

OBJECTIVE

To investigate the causes of reoperation consultation, and the actual percentage and procedures of reoperation after previous orthognathic surgery.

METHODS

The samples consisted of 30 patients who visited our clinic for reoperation consultation from October 2015 to September 2021 (6 males and 24 females; mean age at reoperation consultation, 28.4 y). Patient's causes of reoperation consultation were divided into "esthetic dissatisfaction," "airway changes," "temporomandibular disorders," "uncomfortable occlusion," and "other complications". In terms of esthetic dissatisfaction, the more detailed esthetic problem was evaluated by the clinical chart, facial photographs, and radiographs. In patients who actually underwent reoperation, the actual percentage and procedures of reoperation were investigated.

RESULTS

The most prevalent causes for reoperation consultation were "esthetic dissatisfaction" (n = 21, 70.0%), followed by "airway changes" (n = 11, 36.7%), "uncomfortable occlusion" (n = 8, 26.7%), "other complications" (n = 5, 16.7%), and "temporomandibular disorder" (n = 4, 13.3%). Less than half of patients actually underwent reoperation (n = 13, 43.3%). Actual reoperation procedures included minor revision surgery, reconstruction surgery, or complete reoperation according to the patient's need. In case of complete reoperation, more accurate and predictable results were obtained by using virtual surgical planning, customized surgical guides, titanium surgical plates made with computer-aided design and computer-aided manufacturing technique, and a 3-dimensional printing method.

CONCLUSION

It is important to communicate with patients about expectations for facial esthetic improvement by orthognathic surgery for obtaining the patient's postoperative satisfaction.

Effects of the Orthognathic Surgery on the Voice Characteristics of Skeletal Class III Patients

OBJECTIVES

To analyze the effects of the bimaxillary orthognathic surgery on the voice characteristics of skeletal Class III cases, and to evaluate correlations between acoustic and skeletal changes.

METHOD

Skeletal Class III adult patients (7 male, 18 female) were asked to pronounce the sounds "[a], [ɛ], [ɯ], [i], [ɔ], [œ], [u], [y]" for 3 seconds. Voice records and lateral cephalometric x-rays were taken before the surgery (T0) and 6 months after (T1). Voice records were taken for the control group with 6 months of interval (n=20). The formant frequencies (F0, F1, F2, and F3), Shimmer, Jitter and Noise to Harmonic Ratio (NHR) parameters were considered with Praat version 6.0.43.

RESULTS

In the surgery group, significant differences were observed in the F1 of [e], F2 and Shimmer of [ɯ] and F1 and F2 of [œ] and F1 of [y] sound, the post-surgery values were lower. F3 of [u] sound was higher. In comparison with the control group, ΔF3 of the [ɔ], ΔF3 of the [u] and ΔF1 of the [y] sound, ΔShimmer of [ɛ], [ɯ], [i], [ɔ], [u] and [y], and the ΔNHR of [ɔ] sound significantly changed. The Pearson correlation analysis proved some correlations; ΔF2 between ΔSNA for [ɯ] and [œ] sounds, ΔF1 between ΔHBV for [y] sound.

CONCLUSION

Bimaxillary orthognathic surgery changed some voice parameters in skeletal Class III patients. Some correlations were found between skeletal and acoustic parameters. We advise clinicians to consider these findings and inform their patients.

Three-dimensional evaluation of mandibular condyle and coronoid process according to sex, age, and skeletal deformities

OBJECTIVE

To correlate the volume of the mandibular condyle (MC) and the coronoid process (CP) with sex, age, and skeletal deformities.

METHODS

The structures were visualized through semi-automatic segmentation of the 3D model and complemented with manual segmentation, using the ITK-SNAP 3.0 software. Mann-Whitney, Kruskal-Wallis, and the Dunn test were performed (p < 0.05).

RESULTS

The MC volume showed statistical differences between sex and skeletal deformities. Men and Class III patients showed higher values. CP volume was not influenced by age or skeletal deformities. However, statistical differences were found between sex, with higher values for men.

CONCLUSION

MC volume was influenced by sex and skeletal deformities, while CP was influenced only by sex. Women have smaller volumes for these structures. Age is not correlated with the volume of MC and CP. The highest and lowest values of condylar volume were found for Class III and II individuals, respectively.

Retrospective study on the pharyngeal airspace in the lateral cephalogram - A mathematical model to predict changes due to bimaxillary orthognathic surgery

The aim of this study was the development of a statistical model for reliable prediction of Posterior Airway Space (PAS) changes in lateral cephalograms (LCR) of patients after bimaxillary orthognathic surgery. The LCRs of patients who underwent bimaxillary orthognathic surgery were retrospectively analyzed. The anteroposterior dimension of the PAS was measured at three levels in the pre-operative and postoperative LCR: On the nasopharyngeal (SPAS), oropharyngeal (MAS), and hypopharyngeal level (IAS). The data of 139 patients were collected. The following changes of the PAS were measured: in class II patients SPAS: 0.291 mm (SD = 2.570 mm); MAS: 2.444 mm (SD = 2.986 mm); IAS: 0.750 mm (SD = 3.017 mm); in class III patients SPAS: 1.377 mm (SD 3.212 mm); MAS: 0.962 (SD: = 3.135 mm); IAS: 0.370 mm (SD = 3.468 mm). Linear regression analysis showed for class II patients, a significant influence of mandibular movement on MAS (p = 0.049) and a significant effect of maxillary and mandibular movements on SPAS (p = 0.001) and MAS (p = 0.022) in class III patients. The other jaw displacements had no significant impact on the investigated PAS levels. While the presented method does not permit exact prediction of the dimension of the PAS, it is still an easily accessible method of orientation for the surgeon. The surgeon can initiate three-dimensional examinations to provide exact three-dimensional prediction based on this calculation.

Evaluation of pharyngeal airway and hyoid bone position in skeletal Class 1 individuals with different vertical growth patterns in Turkish population

Amaç: Bu araştırmada, iskeletsel Sınıf 1 ilişkiye sahip bireylerde dik yön büyüme paterninin farengeal havayolu boyutlarına ve hyoid kemik pozisyonuna etkisinin değerlendirilmesi amaçlanmıştır. Gereç ve Yöntem: Bu retrospektif araştırmaya, ANB açısı temel alınarak iskeletsel Sınıf 1 ilişkiye sahip toplam 72 birey (36 kadın, 36 erkek; ortalama yaş: 17.78 ± 1.39 yıl) dahil edildi. Bireyler dik yön büyüme paternine göre; normodiverjan, hipodiverjan ve hiperdiverjan olmak üzere 3 gruba ayrıldı. Lateral sefalometrik radyografiler üzerinde farengeal havayolu ve hyoid kemik pozisyonu ölçümleri, 1 açısal ve 10 lineer ölçüm kullanılarak yapıldı. Verilerin analizinde bağımsız örneklem t-testi ve tek yönlü varyans analizi (ANOVA) kullanılarak grup içi ve gruplar arası farklılıklar değerlendirildi (p&lt;0.05). Bulgular: Verilerin grup içi karşılaştırmalarında farengeal havayolu boyutlarına ait ölçümlerin cinsiyetler arasında benzer olduğu (p˃0.05) ve tüm gruplarda hyoid kemiğin servikal vertebralara ve mandibular düzleme olan uzaklıklarının kızlarda anlamlı düzeyde daha az olduğu görüldü (p&lt;0.05). Normodiverjan, hipodiverjan ve hiperdiverjan bireylerin farengeal havayolu boyutları ve hyoid kemik pozisyonunda istatistiksel olarak anlamlı farklılıklar olmadığı belirlendi. Sonuç: Normodiverjan, hipodiverjan ve hiperdiverjan bireylerde farengeal havayolu boyutlarının ve hyoid kemik pozisyonlarının benzer olduğu görüldü. Bununla birlikte, tüm gruplarda erkeklerde hyoid kemiğinin kızlara göre daha aşağıda ve daha önde pozisyonlandığı belirlendi.

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

The aim of this systematic review was to provide a structured overview of three-dimensional airway volume changes in relation to various orthognathic surgeries. Clinical human studies performing pre- and postoperative three-dimensional airway volume assessments to investigate volumetric changes of the airway after orthognathic surgery were included. Pre-determined inclusion and exclusion criteria were applied in an extensive search of the PubMed, Embase, and Web of Science electronic databases. The cut-off date was set to January 1, 2022. Forty-one articles reporting retrospective and prospective case-control and case series studies were included. All studies were determined to be of medium quality (moderate risk of bias). The included studies were categorized by type of intervention. Pre- and postoperative volumes were extracted from the available data, and volume changes as a percentage of the preoperative levels were calculated. Isolated mandibular setback surgery generally decreased the airway volume. Isolated maxillary or mandibular advancement, bimaxillary advancement, and surgically assisted maxillary expansion generally increased the airway volume in the total airway and oropharynx, among which the effect of bimaxillary advancement surgery appeared most significant. High heterogeneity exists in the terminology and definitions of the airway and its segments. A more uniform methodology for airway volume measurement is needed to provide an insight into the impact on the airway of specific types of surgical intervention. In conclusion, airway volumes are affected after orthognathic surgery, which may be of clinical significance, especially in patients who are predisposed to obstructive sleep apnoea.

Three-dimensional evaluation of hyoid bone position in nasal and mouth breathing subjects with skeletal Class I, and Class II

BACKGROUND

This retrospective study investigated the effect of breathing pattern, skeletal class (Class I, Class II), and age on the hyoid bone position (HBP) in normodivergent subjects.

METHODS

A total of 126 subjects (61 males, 65 females) aged 7-9 years and 10-12 years were scanned using cone-beam computed tomography (CBCT). All participants were classified according to the anteroposterior skeletal pattern into (Class I, Class II). Each skeletal group was further divided according to the breathing mode into mouth breathers (MB) and nasal breathers (NB). The HBP was measured accordingly. Independent sample t-test and Mann Whitney U test were used to detect significant differences between the groups, and binary logistic regression was used to identify MB predictive indicators.

RESULTS

The breathing mode and skeletal class affected the vertical HBP in subjects with 7-9 years, while they affected the anteroposterior HBP in subjects with 10-12 years. Regarding the age effect, hyoid bone was located more anteriorly in the older NB subjects, and hyoid bone was more inferiorly in the older age group. A regression equation of the significant variables was formulated, C3-Me (P: 001, OR: 2.27), and H-EB (P: 0.046, OR: 1.16) were positively correlated with occurrence of MB.

CONCLUSION

There were significantly different HBPs among subjects with different anteroposterior skeletal classes, breathing modes, and age cohorts. Moreover, C3-Me, and H-EB were significant predictors and correlated with increased likelihood of being MB subject.

Evaluation of ortogonblender software bone movement tools in bimaxillary orthognatic surgeries performed in dolphin software

The aim of this observational, longitudinal and retrospective study was to evaluate the fidelity of virtual surgical planning (VSP) performed on Dolphin Imaging & Management Solutions® 11.95 software on hard tissues, using the tools of the open-source software OrtogOnBlender - Blender3D. For this, linear, angular and 7-point anatomical measurements of the skeletal profile were used, and the discrepancies between the VSP and the result after bimaxillary orthognathic surgery were calculated. Pre- and postoperative cone beam CT (CBCT) scans of 43 consecutive patients with class II and III skeletal deformities were evaluated and the results of the VSP were compared to the 1-month postoperative results. All overlapping points presented values within the range considered clinically irrelevant (< 2 mm and < 4°) and differences were not significant (p > 0.05). The comparison of anatomical points showed lower values (≤ 2.11 mm) in point A of class II. For hard tissues, the comparison between VSP and 1-month postoperative tomography demonstrated the faithful results of virtual planning using this software.

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.

Accuracy of three-dimensional soft tissue profile prediction in orthognathic surgery

PURPOSE

To evaluate the accuracy of three-dimensional (3D) soft tissue prediction in bimaxillary orthognathic surgery.

METHODS

Cone-beam computed tomographs of 88 patients with class II (n = 46) and class III (n = 42) malocclusions, who underwent bimaxillary orthognathic surgery, were included in this retrospective study. 3D soft tissue prediction and postoperative outcome were compared by using ten landmarks of facial soft tissues. Patients' sex and age were also assessed. Results were analyzed using a mixed model methodology (p < 0.05).

RESULTS

The success criterion adopted was a mean discrepancy of < 2 mm. Most mandibular landmarks indicated a tendency for underprediction with a downward direction in class II patients, with some values > 2 mm. In class III, there was overprediction with a downward direction for the mandibular landmarks, with values < 2 mm. More accurate results were found in female and older patients.

CONCLUSIONS

3D surgical planning showed clinically acceptable results for predicting soft tissues in patients undergoing bimaxillary orthognathic surgery, with more accurate results for class III patients. Although some differences were found when age and sex were interacted, a consistent association between these variables could not be stated. These results support the clinician, as accuracy can provide a strong guide to the surgeon when planning surgical orthodontic treatment.

Upper Airway Changes Following Different Orthognathic Surgeries, Evaluated by Cone Beam Computed Tomography: A Systematic Review and Meta-analysis

PURPOSE

This study sought to assess the upper airway changes following different orthognathic surgeries using cone-beam computed tomography.

METHODS

An electronic search of the literature was conducted in major electronic databases including Medline (PubMed), Web of Science, Scopus, and Open Grey for articles published up to January 20, 2018. Human studies that evaluated the changes in the volume and minimum cross-sectional area of the upper airway or its subdivisions in patients who had undergone orthognathic surgery by use of cone-beam computed tomography were included. Manual search of the bibliographies of the included articles was also conducted. The included studies underwent risk of bias assessment.

RESULTS

A total of 1330 articles were retrieved. After excluding the duplicates and irrelevant articles, 41 studies fulfilled the eligibility criteria for this systematic review; out of which, 30 entered the meta-analysis. The majority of studies had a medium risk of bias. Mandibular setback, and maxillary advancement + mandibular setback decreased the volume of the upper airway (-6042.87 mm3 and -1498.78 mm3, respectively) and all its subdivisions in long-term (>3 months), except for the nasopharynx, the volume of which increased following maxillary advancement + mandibular setback. Mandibular advancement and maxillomandibular advancement both increased the upper airway volume in long-term (7559.38 mm3 and 7967.06 mm3, respectively); however, only the changes after the former procedure were significant. The minimum cross-sectional area increased after maxillomandibular advancement (161.43 mm2), and decreased following maxillary advancement + mandibular setback (-23.79 mm2) in long-term.

CONCLUSION

There is moderate evidence to suggest that mandibular advancement is the only orthognathic movement that provides a statistically significant change in long-term upper airway volume.

Deep Learning Based Airway Segmentation Using Key Point Prediction

The purpose of this study was to investigate the accuracy of the airway volume measurement by a Regression Neural Network-based deep-learning model. A set of manually outlined airway data was set to build the algorithm for fully automatic segmentation of a deep learning process. Manual landmarks of the airway were determined by one examiner using a mid-sagittal plane of cone-beam computed tomography (CBCT) images of 315 patients. Clinical dataset-based training with data augmentation was conducted. Based on the annotated landmarks, the airway passage was measured and segmented. The accuracy of our model was confirmed by measuring the following between the examiner and the program: (1) a difference in volume of nasopharynx, oropharynx, and hypopharynx, and (2) the Euclidean distance. For the agreement analysis, 61 samples were extracted and compared. The correlation test showed a range of good to excellent reliability. A difference between volumes were analyzed using regression analysis. The slope of the two measurements was close to 1 and showed a linear regression correlation (r2 = 0.975, slope = 1.02, p < 0.001). These results indicate that fully automatic segmentation of the airway is possible by training via deep learning of artificial intelligence. Additionally, a high correlation between manual data and deep learning data was estimated.

Existence of a Neutral-Impact Maxillo-Mandibular Displacement on Upper Airways Morphology

Current scientific evidence on how orthognathic surgery affects the airways morphology remains contradictory. The aim of this study is to investigate the existence and extension of a neutral-impact interval of bony segments displacement on the upper airways morphology. Its upper boundary would behave as a skeletal displacement threshold differentiating minor and major jaw repositioning, with impact on the planning of the individual case. Pre- and post-operative cone beam computed tomographies (CBCTs) of 45 patients who underwent maxillo-mandibular advancement or maxillary advancement/mandibular setback were analysed by means of a semi-automated three-dimensional (3D) method; 3D models of skull and airways were produced, the latter divided into the three pharyngeal subregions. The correlation between skeletal displacement, stacked surface area and volume was investigated. The displacement threshold was identified by setting three ∆Area percentage variations. No significant difference in area and volume emerged from the comparison of the two surgical procedures with bone repositioning below the threshold (approximated to +5 mm). A threshold ranging from +4.8 to +7 mm was identified, varying in relation to the three ∆Area percentages considered. The ∆Area increased linearly above the threshold, while showing no consistency in the interval ranging from -5 mm to +5 mm.

A cross-sectional retrospective study of normal changes in the pharyngeal airway volume in white children with different skeletal patterns. Part 2: Cervical vertebral maturation method and hyoid bone

INTRODUCTION

The purpose of this cross-sectional retrospective study was to evaluate the patterns of pharyngeal airway volume change determined by cervical vertebral maturation (CVM) stage and compare it with that which was characterized by chronological age. Correlations between hyoid bone positions and airway volumes were also examined.

METHODS

CVM staging was determined from cone-beam computed tomography scans of 420 white patients aged 9-15 years. Patients were stratified on the basis of sex and skeletal pattern to establish pharyngeal airway volume clusters for each CVM stage. The horizontal and vertical positions of hyoid bones were measured using Hyoidius and Sella.

RESULTS

Males had larger pharyngeal airway volumes compared with females. In males, the largest increases in pharyngeal airway volumes occurred at an earlier CVM stage than females. No statistically significant differences in pharyngeal airway volumes were noted in subjects with skeletal Class I, II, and III malocclusion. The hyoid bone in males was more anteriorly and inferiorly positioned compared with females. The Class III group had a further forward position of the hyoid bone than the Class I and II groups.

CONCLUSIONS

The patterns of pharyngeal airway change obtained using CVM staging did not correlate well with traditional maturational models for skeletal growth. It implies that chronologic age could be a relatively reliable indicator for the assessment of pharyngeal airway volumes in adolescents, as outlined in part 1 of the present study. Subjects with anteriorly and superiorly positioned hyoid bones exhibited smaller pharyngeal airway volumes, which highlights the role of soft tissue and its influence on airway patency.

How does bimaxillary orthognathic surgery change dimensions of maxillary sinuses and pharyngeal airway space?

OBJECTIVES

To assess changes in the maxillary sinus (MS) and pharyngeal airway space (PAS) after bimaxillary orthognathic surgery using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

The CBCT scans of 48 patients were divided into two groups: group 1: maxillary advancement and mandibular setback (n = 24); group 2: maxillomandibular advancement (n = 24). The CBCTs were acquired 1 to 2 months preoperatively and 6 to 8 months postoperatively. A kappa test was used to determine intra- and interexaminer agreement. Area, volume, and linear measurements of MSs and PASs obtained before and after surgery were compared using a mixed model (P < .05).

RESULTS

All variables of the MS showed significant postsurgical reductions in both groups, except the MS length, which showed a significant increase in group 2. Volume and minimum axial area of PAS showed statistically significant postsurgical increases in both groups (P < .05).

CONCLUSIONS

Despite the reduction in the MS and the increase in the PAS, results indicated that the airway was not negatively affected after maxillomandibular advancement and maxillary advancement with mandibular setback.

Upper airway changes following high oblique sagittal split osteotomy (HSSO)

The aim of this study was to evaluate volumetric changes of the posterior airway space (PAS) following bimaxillary surgery using a high oblique sagittal split osteotomy (HSSO) of the mandibular ramus. The cone beam CTs of Class II and Class III patients taken before (T0) and 6-12 months after surgery (T1) were analyzed using 3D software (Mimics® Innovation Suite 18.0). The PAS was divided into three segments (superior, middle, inferior) by three planes parallel to the Frankfurt horizontal plane intersecting at the posterior nasal spine, the velum palatinum and the epiglottis. Total (TPAS) and partial volumes (SPAS = superior, MPAS = middle, IPAS = inferior) were calculated. For the 25 Class II patients, a highly significant increase (p<0.001) of the total, middle and inferior airway space (TPAS: +33.6%, MPAS: +43.1%, IPAS: +55.9%) was found, while the increase of the upper airway space was statistically not significant (+5.4%, p = 0.074). For the 28 Class III patients, the total, middle and inferior airway space increased statistically insignificantly (TPAS: +4.6%, p = 0.265, MPAS: +2.7%, p = 0.387, IPAS: +2.8%, p = 0.495), while the increase of the upper airway space was statistically significant (+9.7%, p = 0.010). Bimaxillary orthognathic surgery using the HSSO technique led to a significant increase of PAS for Class II patients and could conserve the PAS for Class III patients.

A comparative study of the accuracy between two computer-aided surgical simulation methods in virtual surgical planning

OBJECTIVE

The aim of this retrospective and observational study was to compare the accuracy of two different virtual surgical planning (VSP) protocols, namely, the CASS method and the modified CASS method.

MATERIALS AND METHODS

The patients underwent bimaxillary orthognathic surgery, planned using either the CASS method or the modified CASS method. Linear and angular discrepancies between the VSP outcome and postoperative outcome for both groups were compared for maxilla, mandible, and chin segments. Aside from the comparison between both groups, additional criteria were used to determine the accuracy of the protocol based on a linear and angular difference between planned and actual outcomes of less than 2 mm and 4°, respectively. The intergroup comparisons were performed by one-way ANOVA, with the level of significance set at 5%.

RESULTS

A total of 21 patients, of both genders, were assigned into group I (n = 11), planned with the CASS method, and group II (n = 10), planned with the modified CASS method. Both the CASS and modified CASS methods presented similar accuracy with regard to linear differences for the maxilla, mandible, and chin segments, except for ΔX for the mandibular segment, where the modified CASS method showed slightly better accuracy. However, there was a statistically significant difference with regard to angular differences in the chin segment, with the CASS method shown to be the more accurate. Aside from Δpitch for the chin segment, no linear or angular differences exceeded 2 mm or 4°.

CONCLUSION

Although statistically significant differences were found with regard to angular measurements in the chin segment, the accuracy of the modified CASS method for virtual planning can be considered as clinically equivalent, with a performance comparable to that of the CASS method.

Changes in pharyngeal airway dimensions following incremental and maximum bite advancement during Herbst-rapid palatal expander appliance therapy in late adolescent and young adult patients: a randomized non-controlled prospective clinical study

OBJECTIVES

This was a parallel, assessor-blinded, randomized, non-controlled prospective trial with the objective to evaluate and compare the effects of maximum advancement (MA) and incremental advancement (IA) of mandible with cast-splint-type Herbst-rapid palatal expander (RPE) appliance on pharyngeal airway dimensions and hyoid bone position in skeletal Class II late adolescents and young adults.

MATERIALS AND METHODS

A total of 48 patients (19 male and 29 female, mean age: 15.45 ± 1.42 years) with skeletal Class II malocclusion were treated with cast-splint Herbst-RPE appliance. Inclusion criteria were skeletal Class II malocclusion, mandibular retrognathia, bilateral Class II molar and canine relationship, increased overjet, normal or decreased vertical dimensions, minimal crowding, and no missing teeth. Enrolled subjects were randomly allocated into two groups according to mandibular advancement type: IA and MA Herbst-RPE therapy. The outcome assessor was blinded. Advancement in MA group was adjusted until tête-à-tête incisor relationship or super Class I molar relationship was obtained. Initial forward movement in IA group was 4-5 mm and followed by bimonthly 2 mm of subsequent advancements. Skeletal, pharyngeal airway, and hyoid measurements were performed using lateral cephalometric films. Statistical significance was set at P value of less than 0.05.

RESULTS

Hypopharyngeal airway dimensions (P < 0.000), oropharyngeal airway dimensions (P < 0.001, P < 0.007), and PASmin values (P < 0.010, P < 0.009) were increased and soft palate angle (P < 0.018, P < 0.007) was decreased in MA and IA groups significantly. Hyoid bone measurements revealed a significant difference in H-Cv2 distance (MA: P < 0.002-P < 0.002; IA: P < 0.001-P < 0.043) and H-Cv3 distance (P < 0.005, P < 0.001) for both groups. However, all these changes did not differ among the MA and IA activation groups. ANB°, Wits, overjet, and overbite measurements decreased and SNB°, Co-Gn, Na-Me, ANS-Me, and S-Go increased with the treatment significantly in both mandibular advancement groups (P < 0.000-P < 0.040).

CONCLUSIONS

Herbst-RPE appliance provided a similar improvement in the oropharyngeal and hypopharyngeal airway dimensions and similar changes in sagittal and vertical hyoid position for both maximum and IA protocols in patients with skeletal Class II malocclusion.

TRIAL REGISTRATION

ISRCTN69743543.

Accuracy of 3D virtual surgical planning for maxillary positioning and orientation in orthognathic surgery

OBJECTIVE

This retrospective and observational study evaluated the accuracy of a 3D virtual surgical planning (VSP) for the maxillary positioning and orientation in patients undergoing bimaxillary orthognathic surgery, comparing the planned and postoperative outcomes.

SETTING AND SAMPLE POPULATION

Seventy consecutive patients of both sexes, who were submitted to bimaxillary orthognathic surgery between 2015 and 2019 were included in our study.

MATERIAL AND METHODS

The patients were evaluated by fusing preoperative planning and postoperative outcome using cone-beam computed tomography scan evaluation. Three-dimensional VSP and postoperative outcomes were compared by using three linear and three angular measurements. The main outcome interest was the difference between the VSP movement, and the surgical movement obtained. The success criterion adopted was a mean linear difference of <2 mm and a mean angular difference of <4°.

RESULTS

Results were analysed using a linear mixed model with fixed and random effects, at α = .05. No significant statistical differences were found for linear and angular measurements between the planned and postsurgical outcomes (P > .05). All overlapping points presented values within the range considered clinically irrelevant (<2 mm; <1°).

CONCLUSIONS

Three-dimensional VSP was executed with a high degree of accuracy. When comparing the planned and postsurgical outcomes, all overlapping points presented values within the range considered clinically irrelevant.

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

OBJECTIVE

To evaluate the morphological changes of the upper airway of patients with skeletal Class III malocclusion after undergoing bilateral mandibular ramus dislocated mandibular retrogression (SSRO) or SSRO combined with Le Fort I maxillary osteotomy and 3-dimensional imaging.

METHODS

All previous studies related to the upper airway in patients with skeletal class III malocclusion and orthognathic surgery were collected from the PubMed, EMB, Cochrane Library, Web of science, ClinicalKey, EBSCO, Weipu, Wanfang, China National Knowledge Infrastructure, and Chinese BioMedical Literature databases. The search date ends in August 2017. RevMan5.3 software was used to perform a meta-analysis related to upper airway morphology. Ten studies were included.

RESULTS

The meta-analysis showed that 6 months after SSRO, CV1, and CV2 did not change significantly (P >0.05), whereas CV3 and CV4 narrowed (P <0.05) and remained narrow after 1 year (P <0.05). (CV1,CV2,CV3,CV4: Plans parallel to the FH plane passing through the most anterior inferior point of the anterior arch of the atlas, the 2nd cervical vertebra, the 3rd cervical vertebra, the 4th cervical vertebra.) There was no significant change in nasopharyngeal volume or laryngeal pharyngeal volume (P >0.05), but oropharyngeal volume and total volume decreased (P ≤0.01). Six months after SSRO combined with Le Fort I maxillary osteotomy, the minimum cross-sectional area of the upper airway was smaller (P <0.05), there was no significant change in nasopharyngeal volume or oropharyngeal volume (P >0.05), and oropharynx volume and total volume decreased (P <0.05).

CONCLUSIONS

Single and double jaw surgery has no significant effect on nasopharynx and oropharynx, but reduces laryngopharynx and total volume; however, whether this will result in postoperative obstructive sleep apnea-hypopnea syndrome or become ameliorated over time requires more in-depth study and a longer period of clinical observation.

Linear measurements of sinus floor elevation based on voxel-based superimposition of cone beam computed tomography images

BACKGROUND

Postsurgical evaluation of sinus floor elevation regularly involves linear measurements of the elevated volumes in the cone beam computed tomography (CBCT) images. The accuracy of measurements could be compromised due to ill-defined sinus floor outline if implants are placed simultaneously.

PURPOSE

The aim was to examine a CBCT superimposition method to improve the measurement accuracy.

MATERIALS AND METHODS

Twenty patients who received transalveolar sinus floor elevation with immediate implantation were enrolled. CBCTs before and after surgery were transformed into digital imaging and communications in medicine format and imported into the Dolphin Imaging software. Voxel-based superimposition was automated to merge the files. In the superimposed image, parameters including alveolar bone height, protruded implant length, and total elevated height were measured. The superimposition and measurements were performed independently by two examiners and in two timepoints with 1-week time interval. We used intraclass correlation coefficient (ICC) to analyze the interexaminer and intraexaminer agreements.

RESULTS

Of measured parameters, the mean of difference between two timepoints ranged from 0.18 to 0.26 mm by examiner 1, and from 0.16 to 0.20 mm by examiner 2. ICCs were equal or greater than 0.98, indicating perfect intraexaminer agreement. For interexaminer reliability, the largest mean of difference was 0.27 mm in measuring alveolar bone height between two examiners. ICCs were greater than 0.98, showing perfect interexaminer agreement.

CONCLUSIONS

The voxel-based superimposition of pre- and post-surgical CBCT images with Dolphin Imaging is an effective and reliable way for linear measurements so as to assess the surgical outcome. There is minimal effect on reproducibility of measured data by different timepoints or performers.

Early and long-term changes in the muscles of the mandible following orthognathic surgery

OBJECTIVES

The aim of the present study is to evaluate the early and long-term postoperative dimensional changes of the muscles of the mandible in patients with orthognathic surgery for class II and class III malocclusions by using ultrasonography (US).

MATERIAL AND METHODS

Twenty-six patients who underwent bimaxillary orthognathic surgery for class II or class III malocclusions (14 and 12 patients, respectively) were ultrasonographically examined. The length, width, and cross-sectional area of the masseter and suprahyoid muscles were measured at three different time points: T₀ (preoperatively), T₁ (early postoperatively at 1 month after the surgery), and T₂ (late postoperatively at 9 months). A repeated measures ANOVA was used to calculate statistically significant dimensional changes of the mandibular muscles.

RESULTS

Statistically significant dimensional changes were found postoperatively in class II malocclusion patients only. The digastric muscle showed higher values for the length and lower values for the width (p < .05) at T₁. The geniohyoid muscles were higher in length at T₁ and lower in cross-sectional area (CSA) (p < .05) at T₂. A decreased measured length and an increased measured width were found in case of the mylohyoid muscle (p < .05) at T₂. The early and long-term postoperative dimensional changes of the masseter muscle were not statistically significant.

CONCLUSIONS

The mandibular muscles showed a variable adaptive response to the orthognathic surgery. US should be considered for the long-term follow-up of muscular dimensional changes in class II malocclusion patients.

CLINICAL RELEVANCE

From a clinical perspective, US is a reliable, non-invasive, and widely available method, which allows monitoring the postoperative muscular changes occurring in class II malocclusion patients.

Influence of mandibular setback surgery on three-dimensional pharyngeal airway changes

The aim of this study was to investigate the factors influencing three-dimensional changes in pharyngeal airway space after mandibular setback surgery. Airway changes in 48 skeletal class III patients who had undergone mandibular setback surgery alone (n=25, group 1) or with maxillary surgery (n=23, group 2) were analyzed. Linear parameters, cross-sectional area, and volumes of the pharyngeal airway were evaluated before (T0), immediately after (T1), and 1year after surgery (T2) by cone beam computed tomography. Although the reduced airway volume and cross-sectional area recovered slightly in the long term after surgery, the total pharyngeal airway volume (TPV) was significantly reduced compared to baseline, by 15% in group 1 and 12% in group 2. Regression analysis showed that maxillary posterior impaction in two-jaw surgery had a protective effect on preserving TPV. A change in body mass index from T0 to T2 was an important predictor of decreased TPV in one-jaw surgery patients. Maxillary posterior impaction can be a reliable option for compensating the pharyngeal airway reduction after mandibular setback surgery. Postoperative weight gain can increase the risk of postoperative pharyngeal airway reduction. Therefore, these factors need to be considered before and after mandibular setback surgery.

Three-dimensional pharyngeal airway changes in dento-skeletal class II patients after two-jaw orthognathic surgery with segmentation - a pilot study

PURPOSE

To investigate short- and long-term post-surgical three-dimensional changes of pharyngeal airway morphology and hyoid bone position in dento-skeletal class II deformity patients after two-jaw surgery with segmentation.

METHODS

Relations between skeletal movement, hyoid bone position and three-dimensional pharyngeal airway changes were retrospectively analyzed on pre- and post-surgical CBCTs in dento-skeletal class II patients who underwent orthognathic two-jaw surgery with segmentation.

RESULTS

While long-term significant reductions in length (P= 0.003), surface area (P= 0.042) and volume (P= 0.004) were found in the nasopharynx, the highly significant increases in oropharyngeal airway length, surface area, volume and the minimal cross-sectional area (P < 0.05) prevailed only in the short-term. Although a significant antero-superior movement of the hyoid bone was detected both in short- and long-term follow-up CBCTs (P < 0.05), only its superior, but not the anterior movement was found to be associated with an increased lateral width of the oropharyngeal minimal cross-sectional area.

CONCLUSION

Two-jaw orthognathic surgery with segmentations in dento-skeletal class II patients improved oropharyngeal airway parameters significantly in the short-, but not long-term.

Accuracy of two-dimensional pharyngeal airway space prediction for bimaxillary orthognathic surgery

PURPOSE

The aim of this retrospective study was to evaluate the accuracy of two-dimensional (2D) virtual surgical planning (VSP) of pharyngeal airway space (PAS) in patients submitted to bimaxillary orthognathic surgery.

METHODS

This study was conducted with lateral cephalograms acquired through cone-beam computed tomography records of 33 patients, divided into group 1-patients submitted to maxillary advancement and mandibular setback (n = 17) and group 2-patients submitted to maxillomandibular advancement (n = 16). Records were taken 1 to 2 months prior to surgery, which was used to perform the 2D VSP (T_p), and 6 to 8 months after surgery (T₁). In Dolphin Imaging software, the anteroposterior size of the PAS was calculated at the level of four craniometric points: A, occlusal plane (Mx), B, and pogonion (Pog). Two previously calibrated examiners performed these measurements. Statistical analyses were conducted using Kendall and t tests at a 5% level of significance.

RESULTS

There was a concordance between the two examiners at all points and times. In group 1, points A and B have statistically significant differences between the PAS measurements performed in T_p and T₁, while in group 2, none of the PAS points showed statistically significant differences when comparing T_p to T₁.

CONCLUSIONS

2D computer-based cephalometric prediction in Dolphin Imaging software offers a good orientation to professionals during the surgical procedure of bimaxillary surgeries since its use is considered clinically relevant in daily practice.