Modern trends in Class III orthognathic treatment: A time series analysis

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.

Velopharyngeal Function Change after 2-Jaw Orthognathic Surgery in Patients with Cleft: A Study of 162 Consecutive Cases

BACKGROUND

Orthognathic surgery (OGS) is a common intervention used to correct midfacial hypoplasia in patients with cleft. Previous studies have reported that Le Fort I maxillary advancement may affect velopharyngeal function, but similar investigations focusing on 2-jaw OGS have not been conducted.

METHODS

A total of 162 consecutive patients with cleft lip and palate who underwent 2-jaw OGS between 2015 and 2020 were enrolled. Clinical data were collected, and preoperative and postoperative skeletal measurements were obtained from cephalometric images. Velopharyngeal function was evaluated using perceptual analysis and nasopharyngoscopy. A logistic regression model was used for risk factors associated with changes in velopharyngeal function.

RESULTS

After 2-jaw OGS, 82.1% of patients showed no change in velopharyngeal function, 3.7% experienced improvement, and 14.2% exhibited worsening of function. Changes in velopharyngeal function were statistically significant compared with velopharyngeal status before OGS. Multivariable logistic regression revealed that the amount of maxillary advancement independently predicted the deterioration of velopharyngeal function after OGS (odds ratio, 1.74; 95% CI, 1.20 - 2.52; P = 0.004). The receiver operating characteristic curve based on maxillary advancement demonstrated good discrimination, with an area under the curve of 0.727 (95% CI, 0.62 - 0.83; P = 0.001). The Youden index was 4.27 mm.

CONCLUSIONS

Despite the risk of velopharyngeal function deterioration in patients with cleft palate undergoing OGS, some individuals experienced improved function after 2-jaw OGS. The extent of maxillary advancement has a negative effect on velopharyngeal function.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Three-Dimensional Changes of Condylar Position After Bimaxillary Surgery to Correct Skeletal III Malocclusion: Cone Beam Computed Tomography Voxel-Based Superimposition Analysis

BACKGROUND

The stability of the condylar position within the first 3 months after orthognathic surgery in patients with skeletal Class III malocclusion is crucial for subsequent orthodontic treatment.

PURPOSE

The purpose was to compare condylar positional changes 3 months after bimaxillary surgery to correct skeletal Class III deformities, utilizing the conventional two-dimensional combined with cone beam computed tomography voxel-based superimposition analysis.

STUDY DESIGN, SETTING, SAMPLE

This retrospective cohort study included skeletal Class III patients undergoing bimaxillary orthognathic surgery at Khon Kaen University, Thailand, in 2020. Exclusion criteria were patients with temporomandibular disorder symptoms, facial asymmetry prior to the surgery, or surgical complications.

EXPOSURE VARIABLE

The exposure variable was the timing, both preoperatively and 3 months postoperatively. This 3-month postoperative time point was chosen because complete healing of the bimaxillary surgery is expected by then, without any potential influence of condylar changes resulting from subsequent orthodontic treatment.

MAIN OUTCOME VARIABLES

The outcome variables are condylar position measurement, joint space (mm), and axial condylar angle (degrees).

COVARIATES

Demographics (age, sex) and surgical details (direction and amount of movement) were collected as covariates.

ANALYSES

Statistical analysis of condylar positional changes and correlations was performed using paired t-test and linear correlation (P value < .05), respectively.

RESULTS

The sample included 11 subjects (22 condyles), with a mean age of 24 ± 5.24 years. Both two-dimensional measurements and voxel-based three-dimensional superimposition showed significant changes in condylar position 3 months after bimaxillary surgery: inferior (0.45 ± 0.26 mm, P < .001), posterior (0.46 ± 0.39 mm, P = .003), lateral (0.38 ± 0.42 mm, P = .01) displacement, and inward rotation (5.21 ± 2.54°, P < .001). No significant correlation was found between jaw movement distance and condylar changes.

CONCLUSION AND RELEVANCE

To our knowledge, this is the first study to report measures of condylar changes at 3 months, when complete healing of the osteotomies would be expected, using Le Fort I osteotomy for maxillary advancement combined with bilateral sagittal split ramus osteotomy for mandibular setback. These changes are small in magnitude and may be of little relevance to patient care.

Does artificial intelligence predict orthognathic surgical outcomes better than conventional linear regression methods?

OBJECTIVES

To evaluate the performance of an artificial intelligence (AI) model in predicting orthognathic surgical outcomes compared to conventional prediction methods.

MATERIALS AND METHODS

Preoperative and posttreatment lateral cephalograms from 705 patients who underwent combined surgical-orthodontic treatment were collected. Predictors included 254 input variables, including preoperative skeletal and soft-tissue characteristics, as well as the extent of orthognathic surgical repositioning. Outcomes were 64 Cartesian coordinate variables of 32 soft-tissue landmarks after surgery. Conventional prediction models were built applying two linear regression methods: multivariate multiple linear regression (MLR) and multivariate partial least squares algorithm (PLS). The AI-based prediction model was based on the TabNet deep neural network. The prediction accuracy was compared, and the influencing factors were analyzed.

RESULTS

In general, MLR demonstrated the poorest predictive performance. Among 32 soft-tissue landmarks, PLS showed more accurate prediction results in 16 soft-tissue landmarks above the upper lip, whereas AI outperformed in six landmarks located in the lower border of the mandible and neck area. The remaining 10 landmarks presented no significant difference between AI and PLS prediction models.

CONCLUSIONS

AI predictions did not always outperform conventional methods. A combination of both methods may be more effective in predicting orthognathic surgical outcomes.

Virtual surgical planning in orthognathic surgery: a dental hospital's 10-year experience

PURPOSE

The primary objective of this study was to evaluate how the utilization of virtual surgical planning (VSP) and the epidemiological profile of patients undergoing orthognathic surgery (OGS) have changed in the past decade.

METHODS

The records of patients who had undergone orthognathic surgery at a national dental hospital were reviewed. Trends in VSP, epidemiological data, presentation of dentofacial deformity, and management details were recorded.

RESULTS

A total of 1184 patients were included in this study. The majority of the patients seeking treatment in this dental hospital were young Chinese adults with dentofacial deformities requiring bimaxillary surgeries. Most patients presented with a skeletal Class III pattern (79.0%), and asymmetry was diagnosed in 80.8% of all cases.

CONCLUSION

There was an initial slow pick-up rate for VSP, but this rapidly increased to a high adoption rate of 98.7-100% between 2019 and 2021. Together with an increasing body of evidence suggesting greater accuracy in VSP, utilization in this technology can be enhanced with greater familiarity with the technology and improvements in the VSP services.

Orthognathic Surgery Trending: Retrospective Ten Years Cases Analysis in Nineveh Province, Iraq

AIMS

The study aimed at analyzing patient's case sheets in regard to the incidence of skeletal discrepancy present in cases and its relation with the demographic profile of the sample. All these are chronicled for more than 10 years periods.

METHODOLOGY

This is a retrospective study analysis of the orthognathic case sheets for more than 10 years period. The total numbers of patients are 678. Patient's case sheet was already prepared by the Multi-Disciplinary Team Orthognathic Surgery Clinic in Al-Salam Teaching Hospital, which is the only authorized committee in Nineveh Health Directorate.

RESULTS

The highest age percentage is between (18 and 27 y/76%). Angle class III cases are the uppermost cases (36%) from the total. A significant P value is clear at the level ≤0.05 and ≤0.01 between surgery type and discrepancy in anterior segmental osteotomies (upper and lower) which is performed in bi-maxillary protrusion cases and Angle class II cases (0.01**). Similarly, anterior segmental osteotomies (upper jaw only) which are indicated in both open bite and Angle Class II cases documented as a statistically significant P value (0.02*). The positive correlation is shown in all variables with the disharmony or facial discrepancies. Esthetic and beauty as causes for treatment recorded more than function in relation to time series.

CONCLUSION

This study documents that patients with skeletal class III accounted for the largest percentage (64%) in the study group. A high increase in patients number seeking treatment for their discrepancy is obvious with time from 2009 till 2022.

Comparison between one-jaw and two-jaw designs in virtual surgery planning for patients with class III malocclusion

Orthognathic surgery is highly effective for treating maxillomandibular discrepancies in patients with class III malocclusion. However, whether one- or two-jaw surgery should be selected remains controversial. Our study aimed to evaluate quantitative differences between one-jaw and two-jaw surgical designs. In total, 100 consecutive patients with skeletal class III malocclusion who underwent orthognathic surgery with preoperative three-dimensional simulation between August 2016 and November 2021 were recruited. Based on the same final occlusal setup, a two-jaw surgery design and two types of one-jaw design were created. In total, 400 image sets, including preoperative images and three types of surgical simulation, were measured and compared. The one-jaw mandibular setback design led to improvement in most cephalometric measurements and facial symmetry. Although the one-jaw maxillary advancement design improved the ANB angle and facial convexity, it induced maxillary protrusion and reduced facial symmetry. Compared with the other designs, the two-jaw design provided significantly closer cephalometric measurements to the normative values, better symmetry, and less occlusal cant. Overall, the two-jaw design provided a quantitatively better facial appearance in terms of symmetry, proportion, and profile. Although an optimal surgical design necessitates thorough preoperative evaluation and a shared decision-making process, two-jaw surgery can be considered for improving overall facial esthetics and harmony.

East Asian and Southern European craniofacial class III phenotype: two sides of the same coin?

OBJECTIVES

The skeletal class III phenotype is a heterogeneous condition in populations of different ethnicities. This study aimed to analyse the joint and ethnicity-specific clustering of morphological features in skeletal class III patients of Asian and European origins.

MATERIALS AND METHODS

This cross-sectional study involved South Korean and Spanish participants who fulfilled the cephalometric, clinical, and ethnic-related selection criteria. Radiographic records were standardised, calibrated, and measured. A total of 54 skeletal variables were selected for varimax factorial analysis (VFA). Subsequently, a cluster analysis (CA) was performed (mixed method: k-means and hierarchical clustering). Method error and precision were assessed using ICC, Student's t-test, and the Dahlberg formula.

RESULTS

A total of 285 Korean and Spanish participants with skeletal class III malocclusions were analysed. After performing VFA and CA, the joint sample revealed three global clusters, and ethnicity-specific analysis revealed four Korean and five Spanish clusters. Cluster_1_global was predominantly Spanish (79.2%) and male (83.01%) and was characterised by a predominantly mesobrachycephalic pattern and a larger cranial base, maxilla, and mandible. Cluster_2_global and Cluster_3_global were mainly South Korean (73.9% and 75.6%, respectively) and depicted opposite phenotypes of mandibular projection and craniofacial pattern.

CONCLUSIONS

A distinct distribution of Spanish and South Korean participants was observed in the global analysis. Interethnic and interethnic differences were observed, primarily in the cranial base and maxilla size, mandible projection, and craniofacial pattern.

CLINICAL RELEVANCE

Accurate phenotyping, reflecting the complexity of skeletal class III phenotype across diverse populations, is critical for improving diagnostic predictability and future personalised treatment protocols.

A Cross-Sectional Study of Factors Influencing Pre-Operative Anxiety in Orthognathic Patients

Orthognathic treatment is an important treatment modality to manage severe dentofacial discrepancies. Patients awaiting orthognathic surgery often experience increased anxiety, which may adversely affect post-operative recovery and treatment satisfaction. This study investigated the effects of a number of factors on pre-operative anxiety in orthognathic patients. Seventy patients prospectively recruited from three orthognathic centres in the UK completed a pre-operative questionnaire that included validated scales for measuring anxiety, social support, resilience, and coping styles. Sociodemographic data and satisfaction with the information provided by the clinical team were also elicited from the questionnaire. Univariable analysis showed that social support from a significant other (p = 0.026), resilience (p < 0.001), and satisfaction with the information provided by the clinical team (p = 0.002) were significantly associated with reduced anxiety, whilst avoidance coping (p < 0.001) and coping through seeking social support (p = 0.006) were significantly related to increased anxiety. With the exception of coping by seeking social support, these relationships retained significance in a multivariable regression analysis. Neither gender nor ethnicity moderated the effects of social support on pre-operative anxiety. These findings suggest potential avenues for clinicians to address with future interventions to reduce pre-operative anxiety. Further qualitative research may provide greater clarity on the relationship between these variables and anxiety.

Public interest in Invisalign in developed and developing countries: A Google Trends analysis

Objective:

To investigate long-term changes and possible seasonal variations in Google search volumes related to Invisalign in developed and developing countries.

Design:

Cross-sectional, Google search-based study.

Methods:

Google Trends (GT) was accessed to retrieve the Relative Search Volume (RSV) of Google queries related to the search term ‘Invisalign’ in 10 countries selected on the basis of population size, Internet usage and socioeconomic criteria between 1 January 2004 and 30 June 2021. The countries examined were the following: Australia, Brazil, Italy, Mexico, Philippines, Saudi Arabia, Spain, Thailand, UK and USA. By applying the time series decomposition method, the trend component and the seasonal variation were identified.

Results:

Overall, RSVs regarding Invisalign have increased significantly in all countries with the developed countries outperforming developing countries throughout most of the observation period. There was no meaningful pattern when the trends were compared either on a monthly or quarterly basis. Similar peaks and valleys were found in Australia - Brazil, UK - USA, Italy - Spain and Saudi Arabia - Philippines - Thailand.

Conclusions:

Public interest in online information for Invisalign has grown significantly over the years across countries of diverse socioeconomic and cultural backgrounds while seasonal patterns were observed in the related Google searches. Seasonal fluctuations seemed to follow the academic calendar. The study results may have direct implications on practice management and professional development.

Time series analysis

INTRODUCTION

This article describes a simple method of applying a time series analysis to sample data sets using a free and open statistical software program, Language R.

METHODS

Records of new patients who visited 2 different university-affiliated orthodontic departments in 2 different countries were collected. Time series analysis was performed by applying Language R software. The data sets and codes were provided for tutorial and illustrative purposes.

RESULTS

Using time series decomposition, the trend component and the seasonal variation were separated and visualized graphically.

CONCLUSIONS

Time series analysis may be helpful to clinicians by providing a simple tool to evaluate patient characteristics and manage the practice.

A severe skeletal Class III malocclusion treated with Le Fort I combined with sagittal split ramus osteotomy, mandibular body ostectomy and tongue reduction surgery. A case report

This case report describes the orthodontic-orthognathic management of a 17-year-old male patient with extremely severe skeletal Class III malocclusion due to a marked mandibular protrusion with a small and narrowed upper jaw which increased the remarkable concave facial profile. Dental articulation was entirely lacking, resulting in great difficulty in masticating food. A two-jaw surgery combined with mandibular body ostectomy was performed to correct mandibular asymmetry and the severe sagittal skeletal discrepancy (Wits appraisal –36.5 mm and ANB angle –14.3°). Bi-maxillary surgery was performed in two-stages; the first surgery consisted of maxillary advancement with Le Fort I osteotomy followed by a second surgery where a combination of sagittal split ramus osteotomy (SSRO) and mandibular body ostectomy was performed to correct the severe mandibular prognathism. A partial glossectomy was also carried out to address macroglossia. After a total treatment time of 32 months, a Class I occlusion with a favorable facial profile and lip competence were obtained. The occlusion was made approximately ideal, and mastication improved remarkably. Three years after retention, the occlusion was stable and no relapse was observed. The patient’s complaints and orthodontic problems were completely resolved. Therefore, a combination of two-jaw surgeries with Le Fort I maxillary osteotomy, mandibular SSRO, mandibular ostectomy, and glossectomy may be a viable option in the correction of extremely severe anteroposterior skeletal discrepancy.

Comparison of one-jaw and two-jaw orthognathic surgery in patients with skeletal Class III malocclusion using data from 10 multi-centers in Korea: Part I. Demographic and skeletodental characteristics

Objective

To investigate demographic and skeletodental characteristics of one-jaw (1J-OGS) and two-jaw orthognathic surgery (2J-OGS) in patients with skeletal Class III malocclusion.

Methods

750 skeletal Class III patients who underwent OGS at 10 university hospitals in Korea between 2015 and 2019 were investigated; after dividing them into the 1J-OGS (n = 186) and 2J-OGS groups (n = 564), demographic and skeletodental characteristics were statistically analyzed.

Results

2J-OGS was more frequently performed than 1J-OGS (75.2 vs. 24.8%), despite regional differences (capital area vs. provinces, 86.6 vs. 30.7%, p < 0.001). Males outnumbered females, and their mean operation age was older in both groups. Regarding dental patterns, the most frequent maxillary arch length discrepancy (ALD) was crowding in the 1J-OGS group (52.7%, p < 0.001) and spacing in the 2J-OGS group (40.4%, p < 0.001). However, the distribution of skeletal pattern was not significantly different between the two groups (all p > 0.05). The most prevalent skeletal patterns in both groups were hyper-divergent pattern (50.0 and 54.4%, respectively) and left-side chin point deviation (both 49.5%). Maxillary spacing (odds ratio [OR], 3.645; p < 0.001) increased the probability of 2J-OGS, while maxillary crowding (OR, 0.672; p < 0.05) and normo-divergent pattern (OR, 0.615; p < 0.05) decreased the probability of 2J-OGS.

Conclusions

In both groups, males outnumbered females, and their mean operation age was older. The most frequent ALD was crowding in the 1J-OGS group, and spacing in the 2J-OGS group, while skeletal characteristics were not significantly different between the two groups.

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.

Current Trends in Orthognathic Surgery in Poland—A Retrospective Analysis of 124 Cases

The analysis aims at assessing the current trends in orthognathic surgery. The retrospective study covered a group of 124 patients with skeletal malocclusion treated by one team of maxillofacial surgeons at the University Hospital in Zielona Góra, Poland. Various variables were analysed, including demographic characteristics of the group, type of deformity, type of osteotomy used, order in which osteotomy was performed and duration of types of surgery. The mean age of the patients was 28 (ranging from 17 to 48, SD = 7). The group included a slightly bigger number of females (59.7%), with the dominant skeletal Class III (64.5%), and asymmetries were found in 21.8% of cases. Types of osteotomy performed during surgeries were divided as follows: LeFort I, segmental LeFort I, BSSO, BSSO with genioplasty, LeFort I with BSSO, LeFort I with BSSO and genioplasty, segmental LeFort I with BSSO, isolated genioplasty. Bimaxillary surgeries with and without genioplasty constituted the largest group of orthognathic surgeries (49.1%), and a slightly smaller percentage were one jaw surgeries (46.7%). A statistically significant correlation was found between the type of surgery and the skeletal class. In patients with skeletal Class III, bimaxillary surgeries were performed significantly more often than in patients with skeletal Class II (57.5% vs. 20.0%; p = 0.0002). The most common type of osteotomy in all surgeries was bilateral osteotomy of the mandible modo Obwegeser–Epker in combination with Le Fort I maxillary osteotomy (42.7%). The order of osteotomies in bimaxillary surgeries was mandible first in 61.3% of cases. The longest surgery was bimaxillary osteotomy with genioplasty (mean = 265 min), and the shortest surgery was isolated genioplasty (mean = 96 min). The results of the analysis show a significant differentiation between the needs of orthognathic surgery and the types of corrective osteotomy applied to the facial skeleton.

The Surgery-first Approach to Orthognathic Surgery

ABSTRACT

The purpose of this study was to compare the outcomes between the conventional surgical approach (CSA) and the surgery-first approach (SFA) for both traditional orthognathic osteotomies (LeFort/BSSO) and anterior segmental osteotomies (ASO). This was a retrospective cohort study of patients treated at the Hanoi Plastic Surgery Center from January 2000 to December 2012. The study predictors were the type (LeFort/BSSO or ASO) and timing (CSA or SFA) of surgery. The study outcomes were total treatment time and the rates of complication and relapse. 146 patients were included in the study, of whom 99 (67.8%) were treated with traditional osteotomies and 47 (32.2%) were treated with ASO. In the traditional osteotomy group, there were no significant differences in complication (P = 0.84) or relapse (P = 0.77) rates between CSA and SFA. There were no complications or relapses in the ASO group. Total treatment time was significantly decreased when using the SFA for both orthognathic osteotomies (-3.9 months, P < 0.01) and ASO (-3.3 months, P < 0.01). Our results showed that the SFA was able to achieve similar clinical outcomes to CSA but in a shorter treatment time. The SFA was effective for not only traditional orthognathic osteotomies but also ASO.

How much deep learning is enough for automatic identification to be reliable?

OBJECTIVES

To determine the optimal quantity of learning data needed to develop artificial intelligence (AI) that can automatically identify cephalometric landmarks.

MATERIALS AND METHODS

A total of 2400 cephalograms were collected, and 80 landmarks were manually identified by a human examiner. Of these, 2200 images were chosen as the learning data to train AI. The remaining 200 images were used as the test data. A total of 24 combinations of the quantity of learning data (50, 100, 200, 400, 800, 1600, and 2000) were selected by the random sampling method without replacement, and the number of detecting targets per image (19, 40, and 80) were used in the AI training procedures. The training procedures were repeated four times. A total of 96 different AIs were produced. The accuracy of each AI was evaluated in terms of radial error.

RESULTS

The accuracy of AI increased linearly with the increasing number of learning data sets on a logarithmic scale. It decreased with increasing numbers of detection targets. To estimate the optimal quantity of learning data, a prediction model was built. At least 2300 sets of learning data appeared to be necessary to develop AI as accurate as human examiners.

CONCLUSIONS

A considerably large quantity of learning data was necessary to develop accurate AI. The present study might provide a basis to determine how much learning data would be necessary in developing AI.

Evaluation of Condylar Positional, Structural, and Volumetric Status in Class III Orthognathic Surgery Patients

BACKGROUND AND OBJECTIVES

The need to evaluate the condylar remodeling after orthognathic surgery, using three-dimensional (3D) images and volume rendering techniques in skeletal Class III patients has been emphasized. The study examined condylar positional, structural, and volumetric changes after bimaxillary or single-jaw maxillary orthognathic surgeries in skeletal Class III patients using the cone-beam computed tomography.

MATERIALS AND METHODS

Presurgical, postsurgical, and one-year post-surgical full field of view (FOV) cone-beam computed tomography (CBCT) images of 44 patients with skeletal Class III deformities were obtained. Group 1 underwent a bimaxillary surgery (28 patients: 24 females and 4 males), with mean age at the time of surgery being 23.8 ± 6.0 years, and Group 2 underwent maxillary single-jaw surgery (16 patients: 8 females and 8 males), with mean age at the time of surgery being 23.7 ± 5.1 years. After the orthognathic surgery, the CBCT images of 88 condyles were evaluated to assess their displacement and radiological signs of bone degeneration. Three-dimensional (3D) condylar models were constructed and superimposed pre- and postoperatively to compare changes in condylar volume.

RESULTS

Condylar position was found to be immediately altered after surgery in the maxillary single-jaw surgery group, but at the one-year follow-up, the condyles returned to their pre-surgical position. There was no significant difference in condylar position when comparing between pre-surgery and one-year follow-up in any of the study groups. Condylar rotations in the axial and coronal planes were significant in the bimaxillary surgery group. No radiological signs of condylar bone degeneration were detected one year after the surgery. Changes in condylar volume after surgery were found to be insignificant in both study groups.

CONCLUSIONS

At one year after orthognathic surgery, there were no significant changes in positional, structural, or volumetric statuses of condyles.

Factors associated with the stability of compensatory orthodontic treatment of Class III malocclusion in the permanent dentition

INTRODUCTION

This study aimed to assess the stability of compensatory treatment of Class III malocclusion in permanent dentition.

METHODS

Thirty-six patients (21 women and 15 men; mean age, 20 years) with Class III malocclusion were subjected to the compensatory treatment of permanent dentition and followed up for at least 3 years after orthodontic treatment (T3). Multivariate Poisson regression was performed to assess the influence of clinical, cephalometric, and dental cast variables at the beginning (T1) and the end of treatment on the stability of Class III malocclusion.

RESULTS

Overjet changed from -0.25 mm (-3 to 0.5 mm) at T1 to 1.4 mm (1-2.5 mm) at the end of treatment and 0.8 mm (0-1.5 mm) at T3. Clinical relapse (overjet <1 mm and/or canine Class III relations) was observed in 11 patients (30.6%). Patients treated with extraction of mandibular premolars (risk ratio [RR] = 2.13 × 10^-07, P <0.001), with better orthodontic end outcomes (RR = 1.16, P = 0.009) and which had lower maxillary incisor inclination at T1 (RR = 1.08, P = 0.035) showed a lower risk of relapse. Demographic (sex, age), clinical (length of treatment and posttreatment, number of treatment phases, time of Class III elastics), cephalometric (SNA, SNB, ANB, Wits appraisal, SNGoGn, IMPA), and dental cast (peer assessment rating index and arch dimensions) variables were not significantly associated with clinical relapse at T3.

CONCLUSIONS

The stability of compensatory treatment of Class III malocclusion in permanent dentition is multifactorial, with few predictive variables. Patients treated with extraction and better orthodontic finishing had a lower risk of relapse, whereas larger maxillary incisor inclination at baseline increased the risk of relapse.

Course of the Maxillary Vein and its Positional Relationship With the Mandibular Ramus Require Attention During Mandibuloplasty

PURPOSE

The maxillary vein is associated with major hemorrhage, an intraoperative risk factor during mandibuloplasty. Our objectives in this study were to identify the anatomical course of the maxillary vein relative to the mandible, and to ascertain the relationship of its course with that of the maxillary artery.

METHODS

Thirteen sides of 13 cadavers in the possession of the Department of Anatomy of Tokyo Dental College were used. The maxillofacial region was first dissected, after which the upper part of the mandibular ramus was removed and the maxillary artery, maxillary vein, and pterygoid venous plexus were identified. The length of the maxillary vein and its height from the mandibular plane were then measured, and its anatomical course was recorded.

RESULTS

The maxillary vein ran downward along the inner aspect of the temporal muscle, then from the base of the coronoid process it ran horizontally near the bone surface of the inner aspect of the mandibular ramus. After joining the inferior alveolar vein, it joined the superficial temporal vein to form the retromandibular vein. The mean length of the maxillary vein was 22.2 ± 3.2 mm. At the posterior margin of the mandibular ramus, its mean height above the mandibular plane was 34.2 ± 5.4 mm. From the posterior margin of the mandibular ramus to the lowest point of the mandibular notch, the maxillary vein was located within the areolar connective tissue directly above the periosteum adjoining the inner aspect of the mandibular ramus.

CONCLUSIONS

In the wide area from the center of the maxillary notch to the posterior margin of the mandibular ramus, the maxillary vein runs extremely close to the periosteum on the inner aspect of the mandibular ramus, suggesting that it may pose a risk of hemorrhage in various oral surgical procedures.

Trends in surgical-orthodontic management of Class III malocclusions in Western Australia

Aim

The aim of this retrospective cohort study was to identify trends in the surgical-orthodontic management of skeletal Class III malocclusions in Western Australia between 1985 and 2016.

Methods

The records of 225 patients (132 females, 93 males) who received combined surgical-orthodontic correction of their Class III malocclusion between 1985 and 2016 were retrospectively assessed. The subjects were divided into three groups according to surgery type: Group (1) maxillary advancement only; Group (2) mandibular setback only; Group (3) two-jaw surgery.

Results

A trend towards two-jaw surgery for Class III correction was observed. Between 1985 and 2016, 123 patients (55%) were treated via two-jaw surgery; 97 patients (43%) were treated via maxillary advancement alone and five patients (2%) were treated via mandibular setback alone. Between 2011 and 2016, 61% were treated via two-jaw surgery; 37% were treated via maxillary advancement surgery; 2% were treated via mandibular setback surgery. Gender affected surgery type: two-jaw surgery (60% female); maxillary advancement (62% female); mandibular setback (17% female). A greater proportion of females received Class III surgical management in comparison with males (59:41).

Conclusion

Two-jaw surgery is the most common procedure for the surgical correction of skeletal Class III malocclusions in Western Australia. Of the single jaw procedures, isolated maxillary advancement surgery is more common than mandibular setback procedures.

Evaluating the July Effect in Oral and Maxillofacial Surgery: Part II-Orthognathic Surgery

PURPOSE

The purpose of this study was to determine if there is an increased postoperative complication rate in orthognathic surgery during the first academic quarter (Q1) (July to September).

MATERIALS AND METHODS

The American College of Surgeons National Surgical Quality Improvement Program database was accessed to identify cases with Current Procedural Terminology codes pertaining to orthognathic procedures from 2008 to 2017. Procedures were separated into 2 groups based on time in the academic year: Q1 (July to September) versus remaining quarters (RQ). The inclusion criteria were Current Procedural Terminology codes representing operations resulting in movement of the dentate portion of the jaws and age of 18 years or older. Patient demographic characteristics and perioperative complications were compared between the groups. Descriptive statistics, Fisher exact tests, and χ² tests were executed.

RESULTS

The Q1 cohort included 877 cases, and the RQ cohort included 2,062 cases. The average age of patients was 47.0 ± 19.5 years in Q1 versus 47.2 ± 19.4 years in RQ. The most frequent complications were blood transfusion (11.97% in Q1 vs 12.57% in RQ, P = .64), reoperation (8.67% in Q1 vs 8.84% in RQ, P = .87), and combined superficial and deep-space infection (5.02% in Q1 vs 5.76% in RQ, P = .51). Medical complications involving other organ systems were rare (<1%). Analyses showed no significance between complication rate and time of year.

CONCLUSIONS

The results of this study indicate that there is no association between time of year and complication rates after orthognathic surgery. Additional investigations could be useful in shining light on this topic as it pertains to the training of future surgeons.

Automated identification of cephalometric landmarks: Part 2- Might it be better than human?

OBJECTIVES

To compare detection patterns of 80 cephalometric landmarks identified by an automated identification system (AI) based on a recently proposed deep-learning method, the You-Only-Look-Once version 3 (YOLOv3), with those identified by human examiners.

MATERIALS AND METHODS

The YOLOv3 algorithm was implemented with custom modifications and trained on 1028 cephalograms. A total of 80 landmarks comprising two vertical reference points and 46 hard tissue and 32 soft tissue landmarks were identified. On the 283 test images, the same 80 landmarks were identified by AI and human examiners twice. Statistical analyses were conducted to detect whether any significant differences between AI and human examiners existed. Influence of image factors on those differences was also investigated.

RESULTS

Upon repeated trials, AI always detected identical positions on each landmark, while the human intraexaminer variability of repeated manual detections demonstrated a detection error of 0.97 ± 1.03 mm. The mean detection error between AI and human was 1.46 ± 2.97 mm. The mean difference between human examiners was 1.50 ± 1.48 mm. In general, comparisons in the detection errors between AI and human examiners were less than 0.9 mm, which did not seem to be clinically significant.

CONCLUSIONS

AI showed as accurate an identification of cephalometric landmarks as did human examiners. AI might be a viable option for repeatedly identifying multiple cephalometric landmarks.

Predicting soft tissue changes after orthognathic surgery: The sparse partial least squares method

OBJECTIVES

To develop a prediction algorithm for soft tissue changes after orthognathic surgery that would result in accurate predictions (1) regardless of types or complexity of operations and (2) with a minimum number of input variables.

MATERIALS AND METHODS

The subjects consisted of 318 patients who had undergone the surgical correction of Class II or Class III malocclusions. Two multivariate methods-the partial least squares (PLS) and the sparse partial least squares (SPLS) methods-were used to construct prediction equations. While the PLS prediction model included 232 input variables, the SPLS method included a reduced number of variables generated by a handicapping algorithm via the sparsity control. The accuracy between the PLS and SPLS models was compared.

RESULTS

There were no significant differences in prediction accuracy depending on surgical movements, the sex of the subjects, or additional surgeries. The predictive performance with a reduced set of 34 input variables chosen using the SPLS method was statistically indistinguishable from the full set of variables with the original PLS prediction model.

CONCLUSIONS

The prediction method proposed in the present study was accurate for a wide range of orthognathic surgeries. A reduced set of input variables could be selected through the SPLS method while simultaneously maintaining a prediction level that was as accurate as that of the original PLS prediction model.

Three-dimensional longitudinal evaluation of facial mimicry in orthognathic class III surgery

The effect of bimaxillary orthognathic surgery on facial mimicry was assessed longitudinally in 15 patients with dentoskeletal class III facial dysmorphism (seven men, eight women, mean age 28 years). The patients were analysed pre-surgery and at 6, 12, and 24 months post-surgery while performing verbal (five vowels) and non-verbal (open and closed mouth smile, lip purse) soft tissue facial movements. The three-dimensional motions of right and left nasogenian, crista philtri, cheilion, and lower lip landmarks were detected by an optoelectronic instrument, and a total mobility index was obtained. Differences between the sides were quantified by the symmetry index. Patient values were compared to those collected previously from healthy volunteers by computing z-scores. On average, no significant differences were found in the mobility of the buccal soft tissues at 24 months after surgery (ANOVA P-value, range 0.075-0.808), with positive median z-scores (pooled mean value close to 0.6). Symmetry indices ranged around the control reference values, showing no stage-related differences (Friedman test P-value, range 0.252-0.937), and exceeding 90% for all movements at 24 months after surgery. Bimaxillary osteotomy does not compromise facial mimicry in either verbal or non-verbal facial movements.

Time series analysis of patients seeking orthodontic treatment at Seoul National University Dental Hospital over the past decade

Objective

This paper describes changes in the characteristics of patients seeking orthodontic treatment over the past decade and the treatment they received, to identify any seasonal variations or trends.

Methods

This single-center retrospective cohort study included all patients who presented to Seoul National University Dental Hospital for orthodontic diagnosis and treatment between January 1, 2005 and December 31, 2015. The study analyzed a set of heterogeneous variables grouped into the following categories: demographic (age, gender, and address), clinical (Angle Classification, anomaly, mode of orthodontic treatment, removable appliances for Phase 1 treatment, fixed appliances for Phase 2 treatment, orthognathic surgery, extraction, mini-plate, mini-implant, and patient transfer) and time-related variables (date of first visit and orthodontic treatment time). Time series analysis was applied to each variable.

Results

The sample included 14,510 patients with a median age of 19.5 years. The number of patients and their ages demonstrated a clear seasonal variation, which peaked in the summer and winter. Increasing trends were observed for the proportion of male patients, use of non-extraction treatment modality, use of ceramic brackets, patients from provinces outside the Seoul region at large, patients transferred from private practitioners, and patients who underwent orthognathic surgery performed by university surgeons. Decreasing trends included the use of metal brackets and orthodontic treatment time.

Conclusions

Time series analysis revealed a seasonal variation in some characteristics, and several variables showed changing trends over the past decade.

Extensive Surgical Procedures Result in Better Treatment Outcomes for Bisphosphonate-Related Osteonecrosis of the Jaw in Patients With Osteoporosis

PURPOSE

To identify the risk factors associated with relapse or treatment failure after surgery for bisphosphonate-related osteonecrosis of the jaw (BRONJ) in patients with osteoporosis.

PATIENTS AND METHODS

We performed a retrospective cohort study of BRONJ in patients with osteoporosis who had undergone surgical procedures from 2004 to 2016 at the Department of Oral and Maxillofacial Surgery, Seoul National University Dental Hospital. The predictor variables were a set of heterogeneous variables, including demographic (age, gender), anatomic (maxilla or mandible, or both, affected location), clinical (disease stage, etiology, comorbidities, history of intravenous bisphosphonate intake), time (conservative treatment before surgery, bisphosphonate treatment before the development of BRONJ, discontinuation of the drug before surgery, interval to final follow-up, interval to reoperation in the case of relapse or treatment failure), and perioperative variables (type of anesthesia, type of surgical procedures). The primary outcome variable was relapse after surgery that required reoperation (yes vs no). The descriptive and bivariate statistics were computed to assess the relationships between the study variables and the outcome. To determine the risk factors, we conducted a survival analysis using the Cox model.

RESULTS

The final sample included 325 subjects with a median age of 75 years, and 97% were women. After surgery, 30% of patients did not completely recuperate and underwent repeat surgery. The interval from the first surgery to reoperation ranged from 10 days to 5.6 years. Relapse or treatment failure most often occurred immediately after surgery. The type of surgical procedure and mode of anesthesia were the most important factors in the treatment outcome. A drug holiday did not appear to influence the likelihood of relapse after surgery.

CONCLUSIONS

Treatment of BRONJ in patients with osteoporosis might benefit from more careful and extensive surgical procedures rather than curettage performed with the patient under local anesthesia.