Orthognathic Surgery In Skeletal Class Research Articles

Impacts of mandibular setback with or without maxillary advancement for class III skeletal correction on sleep-related respiratory parameters: A systematic review and meta-analysis.

A systematic review and meta-analysis was conducted to evaluate the impacts of mandibular setback with or without maxillary advancement for class III skeletal correction on respiratory parameters measured by polysomnography (PSG) and to compare these respiratory parameters between these procedures for class III skeletal correction. Six electronic databases were searched up to June 2023. Studies comparing PSG parameters before and after orthognathic surgery for skeletal class III patients were selected for further analysis. The outcomes of interest were apnoea-hypopnea index (AHI), respiratory disturbance index (RDI), the lowest oxygen saturation (lowest SpO2), the average oxygen saturation (mean SpO2), and the 3% oxygen desaturation index (3% ODI). Data extraction, methodological quality assessment, risk of bias assessment, meta-analysis, and subgroup analysis were performed. Sixteen studies with a total of 476 patients who underwent orthognathic surgery for class III skeletal correction were included for meta-analysis. The risk of bias level was moderate for most studies. All PSG parameters before and after orthognathic surgery were not significantly different. The different surgical procedures also did not significantly affect post-operative PSG parameters. 5.8% of patients developed post-operative obstructive sleep apnoea (OSA). Most of them underwent a large distance of mandibular setback. There is a moderate level of evidence that mandibular setback with or without maxillary advancement for class III skeletal correction does not pre-dispose young and healthy patients to obstructive sleep apnoea when evaluated in the short term after surgery. However, post-operatively developed OSA was found in several isolated cases that underwent a large amount of mandibular setback with or without maxillary advancement.

Volumetric analysis of pharyngeal airway dimensions and hyoid bone position following orthognathic surgery in skeletal class III patients: a cross sectional cephalometric study

Background: Objective of the study was to determine linear and volumetric changes in pharyngeal airway dimensions in class III patients treated by different modalities of orthognathic surgery and to compare the results of different orthognathic surgical modalities, and determine the change at the position of the hyoid bone. Methods: Pre and post-treatment lateral cephalogram of 53 class III adult patients who were treated by different modalities of orthognathic surgery studied to assess the changes in pharyngeal airway dimensions and hyoid bone position after orthognathic surgery. 28 patients were treated with mandibular set back, and 25 patients were treated with Bijaw surgery. Lateral cephalogram records were taken before treatment (T1), after surgery (T2), the end of the fixed treatment (T3) and 1 year after debonding (T4).   Results: Interception of both surgical modalities has significant impact on various skeletal and pharyngeal parameters i.e., BMeH (0.00), PNS (0.009), MPS (0.13), GOP (0.001), IPS (0.007), SAS (0.006), and MAS (0.00). OJ (overjet) and OB (overbite) was significant especially after time interval of one year. In Bijaw groups, PPST4 parameter was significantly increased (0.0000), SPST4 (0.000), GOP (0.000), EPS (0.000) and IPS parameter was significantly decreased (0.045). Significant difference was observed in T4 time interval in superior pharyngeal airway space, posterior airway space and middle airway space with (p<0.05). Conclusions: Pharyngeal airway is significantly altered following orthognathic surgery in class III patients and it depends on the type of surgical modality employed were Bijaw surgery has significant impact on oropharyngeal and hypopharyngeal airway space.

Subregional pharyngeal changes after orthognathic surgery in skeletal Class III patients analyzed by convolutional neural networks-based segmentation

ObjectivesTo evaluate the accuracy of fully automatic segmentation of pharyngeal volume of interests (VOIs) before and after orthognathic surgery in skeletal Class III patients using a convolutional neural network (CNN) model and to investigate the clinical applicability of artificial intelligence for quantitative evaluation of treatment changes in pharyngeal VOIs. Methods310 cone-beam computed tomography (CBCT) images were divided into a training set (n = 150), validation set (n = 40), and test set (n = 120). The test datasets comprised matched pairs of pre- and post-treatment images of 60 skeletal Class III patients (mean age 23.1 ± 5.0 years; ANB<-2⁰) who underwent bimaxillary orthognathic surgery with orthodontic treatment. A 3D U-Net CNNs model was applied for fully automatic segmentation and measurement of subregional pharyngeal volumes of pre-treatment (T0) and post-treatment (T1) scans. The model's accuracy was compared to semi-automatic segmentation outcomes by humans using the dice similarity coefficient (DSC) and volume similarity (VS). The correlation between surgical skeletal changes and model accuracy was obtained. ResultsThe proposed model achieved high performance of subregional pharyngeal segmentation on both T0 and T1 images, representing a significant T1–T0 difference of DSC only in the nasopharynx. Region-specific differences amongst pharyngeal VOIs, which were observed at T0, disappeared on the T1 images. The decreased DSC of nasopharyngeal segmentation after treatment was weakly correlated with the amount of maxillary advancement. There was no correlation between the mandibular setback amount and model accuracy. ConclusionsThe proposed model offers fast and accurate subregional pharyngeal segmentation on both pre-treatment and post-treatment CBCT images in skeletal Class III patients. Clinical significanceWe elucidated the clinical applicability of the CNNs model to quantitatively evaluate subregional pharyngeal changes after surgical-orthodontic treatment, which offers a basis for developing a fully integrated multiclass CNNs model to predict pharyngeal responses after dentoskeletal treatments.

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

BackgroundSkeletal 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.MethodsA 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.ResultsSignificant 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.ConclusionsAnteroposterior 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 quantitative changes of condyle in patients with skeletal class III malocclusion after bimaxillary orthognathic surgery with 5-year follow-up.

The present study aimed to characterize three-dimensional (3D) long-term quantitative condyle change including positional, surface, and volumetric alterations in patients with skeletal class III malocclusion treated with bimaxillary orthognathic surgery. Twenty-three eligible patients (9 males, 14 females, mean age: 28.28years old) treated from Jan. 2013 to Dec. 2016 with postoperative follow-up over 5years were retrospectively enrolled. Cone-beam computed tomography scan for each patient was conducted at 4 stages: 1week preoperatively (T0), immediately after surgery (T1), 12months postoperatively (T2), and 5-year postoperatively (T3). Positional changes, surface, and volumetric remodeling of condyle were measured in segmented visual 3D models and statistically compared between stages. Our 3D quantitative calibrations revealed that the condylar center shifted in anterior (0.23 ± 1.50mm), medial (0.34 ± 0.99), and superior (1.11 ± 1.10mm) directions and rotated outward (1.58 ± 3.11°), superior (1.83 ± 5.08°), and backward (4.79 ± 13.75°) from T1 to T3. With regard to condylar surface remodeling, bone formation was frequently observed in the anteromedial areas, while bone resorption was commonly detected in the anterolateral area. Moreover, condylar volume remained largely stable with a minimal reduction during the follow-up. Collectively, although condyle undergoes positional changes and bone remodeling after bimaxillary surgery in patients with mandibular prognathism, these changes largely fall in the range of physical adaptations in the long run. These findings advance the current understanding of long-term condylar remodeling after bimaxillary orthognathic surgery in skeletal class III patients.

Long-term evaluation of masseter muscle activity, dimensions, and elasticity after orthognathic surgery in skeletal class III patients.

To evaluate changes in the masseter muscle after orthognathic surgery using electromyography (EMG), ultrasonography (US), and ultrasound elastography (USE) in individuals with skeletal class III anomaly over long-term follow-up and compare with a control group. The study group included 29 patients with class III dentofacial deformities scheduled to undergo orthodontic treatment and orthognathic surgery. The control group included 20 individuals with dental class I occlusion. Assessment of the masseter muscles using EMG, US, and USE was performed before orthognathic surgery (T1) and at postoperative 3 months (T2) and 1 year (T3) in the study group, and at a single time point in the control group. All assessments were performed at rest and during maximum clenching. Masseter muscle activity, dimension, and hardness were analyzed. Electromyographic activity of the masseter muscle during maximum clenching was increased at postoperative 1 year but did not reach control group values. On ultrasonography, the masseter muscle showed minimal changes in dimension at postoperative 1 year compared to preoperative values and remained below control group values. The postoperative increase in masseter muscle hardness at rest and during maximum clenching persisted at postoperative 1 year. The results of this study suggest that after orthognathic surgery, additional interventions and much longer follow-up are needed to ensure better muscle adaptation to the new occlusion and skeletal morphology. All assessment methods are useful for comprehensively evaluating changes in the masticatory muscles after orthognathic surgery.

The Accuracy and Stability of Intentional Change of Frontal-Ramal Inclination in Orthognathic Surgery for Facial Asymmetry Patients.

Facial asymmetry can be defined as differences in the left and right sides of the face, and most of the patients with facial asymmetry have different left and right frontal-ramal inclinations (FRIs). Restoring the symmetry of both FRIs is important in the surgery of facial asymmetry patients, but it is very difficult to achieve perfect symmetry through conventional orthognathic surgery. However, by using 3-dimensional (3D) virtual planning and CAD/CAM technolo gies, intentional change of FRIs can be possible so the symmetry can be improved. The purpose of this study is to evaluate the surgical accuracy and long-term stability of intentional change of FRIs by 3D virtual surgery, CAD/CAM-assisted orthognathic surgery for patients with facial asymmetry. The study included 20 patients who had undergone orthognathic surgery for skeletal class III malocclusion from January 2019 to December 2021. To evaluate the accuracy of surgery, 3D facial cone beam computed tomography (CBCT) taken immediately after surgery (T1) and virtual surgery data (Tv) were measured and the difference values were calculated. The evaluation of the long-term stability of intentional change of FRI was performed by measuring T1 and T2 (3D facial cone beam computed tomography images taken 6mo after surgery) and the difference values were calculated. The difference values of FRIs in the left and right proximal segments of each patient were calculated. And then, for comparison depending on the direction of rotation, increased FRI groups (n=20, medial rotation) and decreased FRI groups (n=20, lateral rotation) were analyzed separately. As a result, all difference values at both (ΔT1-Tv) and (ΔT2-T1) were <1 degree. As a result of analyzing the entire FRI by dividing it into decreasing and increasing groups, the mean value of (ΔT1-Tv) was 0.225 degrees for the decreasing group and 0.275 degrees for the increasing group. It means that the proximal segment moved less than the movement implemented by the virtual surgery through actual surgery but it shows a very small error, which means that the overall operation almost accurately implements the virtual surgical planning. Compared with (ΔT1-Tv), the mean value of (ΔT2-T1) showed a much smaller error value, and no specific tendency was observed. This indicates that the stability after surgery is very good. Based on this study, using 3D virtual surgery planning and CAD/CAM technologies for treating patients with facial asymmetry was very useful, and surgery could be performed accurately and predictably. In particular, left-right symmetry was almost perfectly achieved through virtual simulation and could be implemented through actual surgery. Therefore, it can be said that the use of these 3D technologies is recommended for the surgical approach of facial asymmetry.

Artificial Intelligence Splint in Orthognathic Surgery for Skeletal Class III Malocclusion: Design and Application.

Digital splints are indispensable in orthognathic surgery. However, the present design process of splints is time-consuming and has low reproducibility. To solve these problems, an algorithm for artificial intelligent splints has been developed in this study, making the automatic design of splints accessible. Firstly, the algorithm and program of the artificial intelligence splint were created. Then a total of 54 patients with skeletal class III malocclusion were included in this study from 2018 to 2020. Pre and postoperative radiographic examinations were performed. The cephalometric measurements were recorded and the difference between virtual simulation and postoperative images was measured. The time cost and differences between artificial intelligent splints and digital splints were analyzed through both model surgery and radiographic images. The results showed that the efficiency of designing splints is significantly improved. And the mean difference between artificial intelligent splints and digital splints was <0.15mm in model surgery. Meanwhile, there was no significant difference between the artificial intelligent splints and digital splints in radiological image analysis. In conclusion, compared with digital splints, artificial intelligent splints could save time for preoperative design while ensuring accuracy. The authors believed that it is conducive to the presurgical design of orthognathic surgery.

Comparison of the Post-Surgical Position of the Temporomandibular Joint after Orthognathic Surgery in Skeletal Class III Patients and Patients with Cleft Lip and Palate.

Objective: The purpose of our research is to compare the post-surgical position of the temporomandibular joint in skeletal Class III patients and patients with cleft lip and palate treated with two-jaw orthognathic surgery using a three-dimensional computer tomography image. Materials and Methods: Twenty-three skeletal Class III patients with mandibular prognathism associated with maxillary retrognathism in group 1 and twenty cleft mid-face retrusion skeletal Class III patients in group 2 were enrolled in this study. All subjects were treated with two-jaw orthognathic surgery. Computed tomography scans were taken in all subjects at 3 weeks preoperatively and 6 months postoperatively. Three-dimensional craniofacial skeletal structures were build-up, and assessed the temporomandibular joint position changes before and after surgery. Results: Forty-three selected patients were separated into two groups. The mean age of patients was 22.39 ± 4.8 years in group 1 and 20.25 ± 3.8 years in group 2. The range of mean three-dimensional discrepancy of the selected condylar points was 0.95–1.23 mm in group 1 and 2.37–2.86 mm in group 2. The mean alteration of intercondylar angle was 2.33 ± 1.34° in group 1 and 6.30 ± 2.22° in group 2. The significant differences in the discrepancy of TMJ and changes in intercondylar angle were confirmed within the intra-group and between the two groups. Conclusions: Significant changes in postoperative TMJ position were present in both groups. Furthermore, the cleft group presented significantly more postoperative discrepancy of TMJ and more changes in intercondylar angle after surgery. This finding may be a reason leading to greater postoperative instability in cleft patients compared with skeletal Class III non-cleft patients. Clinical Trial Registration Number: IRB No: 202201108B0.

Surgical Accuracy of 3D Virtual Surgery and CAD/CAM-Assisted Orthognathic Surgery for Skeletal Class III Patients.

Orthognathic surgery is an effective surgical method to achieve functionality and facial esthetics for mandibular prognathism. If surgery is performed with a conventional method, errors may occur in the surgical preparation process and the surgical procedures, and there is a limitation in that the accuracy of surgery is determined according to the surgeon's experience and tactual sense. However, with the recent development of three-dimensional (3D) virtual planning and CAD/CAM technology, more 3D and predictable surgical planning and more accurate and time-saving surgery have become possible. The purpose of this study is to evaluate the surgical accuracy of 3D Virtual Surgery, CAD/CAM-Assisted Orthognathic surgery for Skeletal Class III Patients. The study included 18 patients who had undergone orthognathic surgery for skeletal class III malocclusion from January 2020 to December 2021. To evaluate the accuracy of the virtual planning, 3D facial cone-beam computed tomography taken immediately after surgery (T1) and virtual surgery data (Tv) were superimposed in each patient. Landmarks were set on each of the maxillary segment, mandibular distal segment, and left and right mandibular proximal segment, and the difference between T1 and Tv was compared 3D on the x , y , and z -axis. (ΔT: T1-Tv). As a result, the average distance between Tv and T1 at each landmark, all landmarks except for the posterior nasal spine of the maxillary segment showed <1mm. In particular, the differences across the x and z -axis were very small, while the difference across the y -axis tend to be large. The comparison of the position of each segment in virtual surgery and actual surgery was as follows. It can be seen that all segments were located slightly downward, and the medial pole of the mandibular proximal segment was located posterolateral and the lateral pole was located anteromedial after the actual surgery compared with the virtual planning. It means that the proximal segment was slightly rotated, but the difference was within 1mm, so it can be considered that the surgery was accurate. Base on this study, orthognathic surgery using 3D virtual surgery planning and CAD/CAM technologies was very accurate. By applying these cutting-edge technologies to clinical practice, it was possible not only to increase the predictability of surgery but also to improve the convenience of surgery. Therefore, it is thought that it will be important for clinicians to make continuous efforts to applicate cutting-edge technologies to be developed in the future to patient diagnosis and surgery.

Four‐dimensional assessment of facial expression before and after orthognathic surgery in skeletal Class III patients

AbstractAimIt is widely known that orthognathic surgery affects changes in facial soft tissue morphology. However, the effect of orthognathic surgery on facial expression remains to be verified. The purpose of this study was to examine the pros and cons of the effects of orthognathic surgery on facial expression in skeletal Class III patients.MethodsFifteen patients (5 males, 10 females) were captured pre‐surgery and at 6 months' post‐surgery using Kinect camera while performing facial soft tissue movements (opening mouth, smiling, and blowing). The three‐dimensional coordinates, amount of movement, and velocity of the eight facial soft tissue landmarks during motion were obtained. As controls, 15 Japanese healthy volunteers with Class I occlusion were included.ResultsDifferences in the three‐dimensional coordinate values during movement were confirmed, and there were some landmarks in the lower face region of the preoperative patient that showed significant differences compared with the control. Total amount of movement and velocity of Pogonion during smiling were significantly smaller than those of the control group, but there was no significant difference between the control and postoperative groups at any landmarks after surgery. It was suggested that patients with skeletal Class III may have limited movement in some movements, and it was confirmed that with orthognathic surgery, the aspect of movement would be similar to that of the control.ConclusionsOrthognathic surgery may be beneficial to the facial muscles without limiting facial movements.

Evaluation of mandibular positional changes after orthognathic surgery in skeletal class II and class III surgery-first approach patients

PurposeThe aim of this study was to predict and compare postoperative changes of mandibular position between mandibular setback and advancement surgery in a surgery-first approach (SFA). Materials and methodsThe study population included patients who underwent mandibular setback or advancement surgery using bilateral sagittal split ramus osteotomy, those were divided into two groups: mandibular setback and advancement surgery. Surgical and postoperative mandibular positional changes were evaluated by lateral cephalograms and CTs taken within 2 months before surgery (T0), 1 week after surgery (T1), and after the debonding procedure (T2). The postoperative mandibular positional changes were predicted from the increase in vertical dimension (VD) in surgical occlusion and the counterclockwise rotation to the preoperative VD on the lateral cephalograms and CT at T1. Furthermore, resultant measurement on postoperative mandibular positional changes was performed. Finally, we compared the prediction with actual positional changes of the mandible after the debonding procedure. ResultsNine SFA patients with mandibular setback surgery and six with advancement surgery were evaluated and significant mandibular changes from T0 to T1 and from T1 to T2 were observed. Negative correlation between horizontal surgical changes and postoperative horizontal changes was present in both groups. The difference between the predicted and actual amount of postoperative mandibular movement was significant in the mandibular advancement surgery group. ConclusionPostoperative mandibular relapse appeared much larger in the mandibular advancement surgery group than in the setback group. Therefore, it is more important to consider the postoperative mandibular position change in mandibular advancement surgery in SFA.

Main approaches of three-dimensional (3D) imaging examinations in the assessment, treatment, and follow-up of patients with skeletal Class III: a concise systematic review

Introduction: Class III malocclusion presents with several skeletal and dental factors, highlighting the large or protruding jaw, retrusive maxilla, protrusive mandibular dentition, retrusive maxillary dentition, or combinations. The importance of evaluating class III malocclusions, as well as their treatments, through three-dimensional (3D) images are highlighted. Objective: To present a concise systematic review of the approach of 3D imaging exams to conduct class III malocclusion treatments, as well as to follow up after orthognathic surgery. Methods: Clinical studies with qualitative and/or quantitative analysis were included, following the rules of the systematic review-PRISMA. Results and Conclusion: A total of 105 articles was found involving class III malocclusion and ortho-surgical treatments guided by three-dimensional (3D) images. A total of 44 articles were fully evaluated and 16 were included and discussed in this study. Positional, structural, and volumetric condylar changes after orthognathic surgery in skeletal Class III patients have been well elucidated using cone-beam computed tomography. In addition, the virtual surgical planning and the surgical splint manufactured in CAD/CAM facilitate treatment planning and offer an accurate surgical result in orthognathic surgery. The application of pre-engineered bone guidance splints allows the treatment of craniofacial deformities with precision. Therefore, the three-dimensional (3D) tool allows for the accuracy of treatments and planning of orthognathic surgery, as well as the best postoperative follow-up.

Correction of Severe Skeletal Class II High Angle with Mandibular Retrusion and Gummy Smile by Double-Jaw Surgery.

This report describes the treatment of severe skeletal Class II malocclusion in a young woman with a gummy smile and pronounced lower anterior facial height. Overjet and overbite were +12.0 mm and -1.0 mm, respectively. Cephalometric analysis revealed inferior positioning of the maxilla and severe mandibular retrusion with clockwise rotation. Both the upper and lower anterior teeth showed labial inclination. Based on a diagnosis of a skeletal Class II high angle with mandibular retrusion and a gummy smile, double-jaw orthognathic surgeries for upper and lower premolar extraction were chosen to gain ideal occlusion and an improvement in the esthetic facial profile. Le Fort I osteotomy was performed to move the anterior and posterior teeth upward by 4.0 mm and achieve mandibular counterclockwise rotation. Short lingual sagittal split ramus osteotomy was performed to move the mandible forward by 3.0 mm. As a result, normal overjet and overbite were achieved together with a straight profile and a good smile. After surgery, electromyographic evaluation of anterior temporal muscle activity showed an improvement in the percentage overlapping coefficient value (a symmetric index of bilateral muscle activity) from 28.1% to 63.2% compared to at pre-treatment. The pattern of jaw movement also showed an improvement. These results suggest that orthognathic surgery in skeletal Class II cases can improve not only malocclusion and the skeletal relationship of the jaws, but also masticatory function and jaw movement.

Surgery-first approach reduces the overall treatment time without damaging long-term stability in the skeletal class III correction: a preliminary study

BackgroundCompared to the conventional approach, including preoperative orthodontic preparation, the so-called surgery-first approach (SFA) seems to reduce the overall treatment time in the correction of skeletal class III dentofacial deformity. However, there have been controversies about postoperative skeletal stability with SFA. Therefore, we investigated the long-term stability and the overall treatment time after maxillomandibular surgery for skeletal class III correction with or without preoperative orthodontic preparation.MethodsThis retrospective study included eight patients who underwent maxillomandibular surgery for class III correction with the SFA (SFA group) and 20 patients who underwent the conventional approach (CA group). A comparative study of the change in the maxillary and mandibular position on preoperative (T1), 1-day (T2), 6-month (T3), and 2-year (T4) postoperative lateral cephalograms. We calculated the overall treatment time for each group.ResultsAt the presurgical stage (T1), there was no bias in the skeletal features between the two groups. In the surgical change from T1 to T2, the mandible (point B) of the CA group was significantly moved superiorly. Short-term changes from T2 to T3 revealed that the mandible moved forward in both groups, whereas the maxillary position showed no significant changes. Long-term changes from T3 to T4 demonstrated that none of the measured parameters showed any significant differences. Finally, the average of overall treatment time was 15.1 months in the SFA group and 26.0 months in the CA group.ConclusionsThese findings suggest that SFA in bimaxillary orthognathic surgery for skeletal class III correction leads to predictable long-term skeletal stability, similar to surgery with CA. Furthermore, SFA reduced the overall treatment time compared to CA.

Long-term condylar remodelling after bimaxillary orthognathic surgery in skeletal Class III patients

In this study, we aimed to evaluate long-term condylar remodelling in skeletal Class III patients who underwent bimaxillary orthognathic surgery using cone-beam computed tomography (CBCT). Twenty-three patients were studied retrospectively, and a total of 4 CBCT scans were obtained for each subject: 1 month before surgery (T0), immediately after the surgery (T1), 6 months after the surgery (T2), and 6.1 (±2.1 years after the surgery) (T3). Condylar remodelling was measured using the condylar volume, height, width, and depth. To examine a significant change, a one-way repeated measures analysis of variance was performed. The correlation between postoperative skeletal movement and condylar volume was assessed using Spearman’s correlation analysis. Condylar volume and height showed a significant decrease from T1 to T2 but a significant increase from T2 to T3. Furthermore, a significant decrease was observed between T1 and T3. The condylar width and depth showed no significant changes. Postoperative skeletal movement showed no correlation with the change in condylar volume. The change in condylar volume mostly occurred as the condylar height changed. However, it did not contribute much to the postoperative skeletal movement.

The Effect of Orthognathic Surgery on the Hyoid Bone Position in Skeletal Class III Patients: An Evaluation Using Cephalometric Analysis.

BACKGROUNDThis study aimed to investigate the positional changes of the hyoid bone following orthognathic surgery in skeletal class III patients.METHODSThis double-blinded quasi-experimental study was carried out in Mashhad University of Medical Sciences, Iran, from Apr 2019 to Jun 2020. All skeletal Class III patients who were candidates for orthogenetic surgery were included. They underwent mandibular setback surgery using bilateral sagittal split osteotomy. Cephalometric assessments in relation to hyoid bone position and posterior airway space (PAS) were conducted one day preoperatively (T0), as well as one week (T1), six months (T2) and one year (T3) postoperatively, determining the parameters like the Long axis of the hyoid bone (LAH), Retrognation (RGn), Hyoidale (H), Palatal plane (PP), Mandibular plane (MP) and C3 Vertebrae (C3). All cephalograms were examined using AudaxCeph, Planmeca software. The data analysis was performed via SPSS-19 (P<0.05)RESULTS25 class III patients, including 18 females (72%) and 7 males (28%) with a mean age of 24.32±5.87, were studied. The cephalometric analysis demonstrated significant decreases in variable angles during the follow-up periods, except for LAH-MP angle (P<0.001). The hyoid bone moved downward and backward relative to its original position following the mandibular setback surgery. However, the bone gradually returned to the preoperative location between 6 to 12 months postoperatively. CONCLUSIONThe findings revealed the downward and backward movement of the hyoid bone following the mandibular setback surgery, returned near to its preoperative position after 1 year, postoperatively.

Orthognathic Surgery in Skeletal Class l Patient with Facial Asymmetry

The purpose of this case report was to describe the considerations in surgical orthodontic treatment of a patient with skeletal Class I malocclusion and facial asymmetry. A 22-year-old male presented with a chief complaint of facial asymmetry. Clinical examination showed severe facial asymmetry to the right side at his chin point. Also he showed lip canting and straight facial profile. Intraorally, he exhibited posterior crossbite in the right side with severe mandibular dental midline deviation to the right. After presurgical orthodontic treatment with dental decompensation was done, sagittal split ramus osteotomy (SSRO) with mandibular body shaving was done to correct the mandibular asymmetry. After orthodontic treatment, posterior crossbite and midline of the dentition was corrected, and asymmetry of the mandible was improved. For the patient with facial asymmetry, it is critical to eliminate dental compensation orthodontically and to move the teeth to their proper positions to avoid relapse and obtain stability.

A New Approach to Set the Absolute Midsagittal Plane of the Mandible Using a Similarity Index in Skeletal Class III Patients with Facial Asymmetry

This study sought to test the feasibility of a newly developed plane called computed modified absolute mandibular midsagittal plane (cmAMP) based on the similarity index (SI) for evaluating the stereoscopical symmetry of the mandible by comparison with other proposed midsagittal planes. This study involved 29 adult patients (15 men, 14 women; average age, 23.1 ± 6.9 years) with skeletal Class III facial asymmetry who underwent bimaxillary orthognathic surgery. Using cone-beam computed tomography images taken before and 1 year after surgery, cmAMP with the highest SI value between the two anterior segments of the hemi-mandible was set by a computer algorithm. Results show that the SI using cmAMP had the highest value (0.83 ± 0.04) before surgery compared to the other midsagittal planes, and was not significantly different from the SI (0.80 ± 0.05) using a facial midsagittal plane (MSP) after surgery. The distance (1.15 ± 0.74 mm) and angle (2.02 ± 0.82°) between MSP and cmAMP after surgery were significantly smaller than those between MSP and other midsagittal planes. In conclusion, the cmAMP plane best matches the two anterior segments of hemi-mandible symmetrically and is the closest to MSP after orthognathic surgery in skeletal Class III patients with facial asymmetry.

Effects of different nose types on class II treatments for female patients

BackgroundThe aim of this study was to evaluate the effect of different nose types on the perception of facial aesthetics following camouflage treatment and orthognathic surgery for skeletal class II female patients.MethodsA pre-treatment profile photograph of a skeletal class II adult patient was selected from the department archive. Two constructed photographs were created to represent orthognathic surgery and camouflage treatments with the aid of computer software. A total of 18 constructed images was composed using three profiles (pre-treatment, post-camouflage, and post-orthognathic surgery) and six nose types. These photographs were shown to the three groups (orthodontists, plastic surgeons, and lay people), and they were asked to assign an attractiveness score to each photo ranging from 0 to 100, with 0 indicating the least attractive and 100 indicating the most attractive.ResultsFor the convex nose profiles, anterior movement of the mandible obtained by orthognathic surgery did not result in a significant change in the scores given by the lay people. When surgical or camouflage treatment was not implemented and, instead, just rhinoplasty was performed for these profiles, there was a significant increase in the aesthetic scores given by all groups. For the straight nose profiles, orthognathic surgery increased the attractiveness scores given by all groups. Furthermore, for all the profiles, extraction treatment did not affect the aesthetic scores given by any of the groups (P > 0.05).ConclusionsThe lay people perceived that having a convex-bridged nose was a bigger problem than having a retrognathic profile. Overall, in terms of skeletal and dental orthodontic treatments, nose shape should be considered during the treatment planning process.