Machine Learning Effectively Diagnoses Mandibular Deformity Using Three-Dimensional Landmarks.

BACKGROUND: Jaw deformity diagnosis requires objective tests. Current methods, like cephalometry, have limitations. However, recent studies have shown that machine learning can diagnose jaw deformities in two dimensions. Therefore, we hypothesized that a multilayer perceptron (MLP) could accurately diagnose jaw deformities in three dimensions (3D). PURPOSE: Examine the hypothesis by focusing on anomalous mandibular position. We aimed to: (1) create a machine learning model to diagnose mandibular retrognathism and prognathism; and (2) compare its performance with traditional cephalometric methods. STUDY DESIGN, SETTING, SAMPLE: An in-silico experiment on deidentified retrospective data. The study was conducted at the Houston Methodist Research Institute and Rensselaer Polytechnic Institute. Included were patient records with jaw deformities and preoperative 3D facial models. Patients with significant jaw asymmetry were excluded. PREDICTOR VARIABLES: The tests used to diagnose mandibular anteroposterior position are: (1) SNB angle; (2) facial angle; (3) mandibular unit length (MdUL); and (4) MLP model. MAIN OUTCOME VARIABLE: The resultant diagnoses: normal, prognathic, or retrognathic. COVARIATES: None. ANALYSES: A senior surgeon labeled the patients' mandibles as prognathic, normal, or retrognathic, creating a gold standard. Scientists at Rensselaer Polytechnic Institute developed an MLP model to diagnose mandibular prognathism and retrognathism using the 3D coordinates of 50 landmarks. The performance of the MLP model was compared with three traditional cephalometric measurements: (1) SNB, (2) facial angle, and (3) MdUL. The primary metric used to assess the performance was diagnostic accuracy. McNemar's exact test tested the difference between traditional cephalometric measurement and MLP. Cohen's Kappa measured inter-rater agreement between each method and the gold standard. RESULTS: The sample included 101 patients. The diagnostic accuracy of SNB, facial angle, MdUL, and MLP were 74.3, 74.3, 75.3, and 85.2%, respectively. McNemar's test shows that our MLP performs significantly better than the SNB (P = .027), facial angle (P = .019), and MdUL (P = .031). The agreement between the traditional cephalometric measurements and the surgeon's diagnosis was fair. In contrast, the agreement between the MLP and the surgeon was moderate. CONCLUSION AND RELEVANCE: The performance of the MLP is significantly better than that of the traditional cephalometric measurements.

Sagittal Cephalometric Evaluation Without Point Nasion: Sagittal G-Triangle Analysis.

ABSTRACT: This study aims to introduce a new sagittal cephalometric measurement, the sagittal G-triangle analysis, to accurately and reproducibly assess the sagittal jaw relationship. Sagittal G-triangle analysis, which consists of angles AXK and BXK, is based on an equilateral triangle (Bo-X-K) constructed using 5 cephalometric landmarks (Ba, Bo, Po, Or, and G). To test the diagnostic efficiency of this analysis, pretreatment cephalometric radiographs of 120 female and 120 male Chinese patients were randomly selected. For each enlisted subject, angles SNA and SNB as well as angles AXK and BXK were measured and recorded. On the basis of the SNA and SNB results, subjects were categorized into 6 groups: maxillary retrognathism, normal maxilla, maxillary prognathism, mandibular retrognathism, normal mandible, and mandibular prognathism. The diagnostic efficiency of angles AXK and BXK were evaluated using various statistical tests. A high correlation was detected between angles SNA and AXK as well as between angles SNB and BXK. Female patients with angle AXK between -2.255° and 2.860° and male patients with angle AXK between -2.615° and 2.120° were considered to have a normal maxilla position. Female patients with angle BXK between -2.61° and 2.93° and male patients with angle BXK between -2.275° and 0.610° were considered to have a normal mandible position. In conclusion, sagittal G-triangle analysis could be used as an alternative method for the evaluation of the sagittal position of the maxilla and mandible in cephalometric analysis.

[Orthodontic treatment of adult patients with mandibular retrognathia]. / Ortodonticheskoe lechenie vzroslykh patsientov s nizhnei retrognatiei.

This article describes a case report of the patient with mandibular retrognathia, class II malocclusion, constriction and deformation of dental arches and bimaxillary protrusion. Due to the patient's refuse to undergo the orthognathic surgery, after diagnostic, it was decided to carry out the orthodontic dentoalveolar compensation. The combined use of the functional fixed telescopic appliance (FFTA), bracket system and orthodontic miniscrews made it possible to effectively normalize the mandibular position, achieve orthognathic occlusion, eliminate bimaxillary protrusion and improve the face profile. This method significantly reduced invasiveness and time of orthodontic treatment.

Neuroimaging findings in Emanuel Syndrome.

Emanuel syndrome is a rare inherited chromosomal abnormality caused by an unbalanced translocation of chromosomes 11 and 22. Clinically, Emanuel syndrome is characterized by a wide spectrum of congenital anomalies, dysmorphisms, and developmental disability often confused with other similar syndromes. Outside of genetic testing, diagnosis remains challenging and current literature on typical radiologic findings is limited. We present classic neuroimaging findings of Emanuel syndrome consistent with prior literature including microcephaly, microretrognathia, external auditory canal stenosis, and cleft palate; and also introduce the additional maxillofacial anomaly of dysplastic middle ear ossicles, to our knowledge not previously described in the literature. Recognition of findings leading to earlier diagnosis of Emanuel syndrome may improve outcomes and quality of life for patients and their families.

Three-dimensional volumetric analysis of condylar head and glenoid cavity after mandibular advancement.

The aim of this study was to assess condylar resorption, spatial change in glenoid cavity, and its risk factors after mandibular advancement by three-dimensional volumetric analysis. Subjects consisted of 30 condyles of 15 patients diagnosed with mandibular retrognathism who underwent Le Fort I and bilateral sagittal split ramus osteotomy advancement. CBCT images were taken before surgery (T0), immediately after surgery (T1), and postoperatively at 6 months (T2) and 1 year (T3). Condylar resorption was observed in 21 condyles. The posterior was the most affected region, while the anterior was the least affected. The volume of the glenoid cavity was significantly increased after surgery regardless of the presence or absence of resorption. However, the cavity recovered close to its original volume over time. At 1 year after surgery, the volume was not significantly different from the preoperative volume. Counterclockwise rotation of the proximal segment was found to be a risk factor affecting resorption based on correlation analysis. Mandibular advancement appeared to generate excessive mechanical stress on the posterior condyle, and might be responsible for the resorption. Counterclockwise rotation might have added stress to the region. Articular spatial change was transient and did not appear to be related to condyle resorption.

Impact of orthognathic surgery on velopharyngeal function by evaluating speech and cephalometric radiographs.

BACKGROUND: Maxillary retrognathia is a well-known consequence of abnormal facial growth in patients with cleft lip and palate. Orthognathic surgery improves facial appearance and occlusion but may induce velopharyngeal insufficiency. The aim of this study was to evaluate the effect of orthognathic surgery on velopharyngeal function by using speech analysis and lateral cephalometric radiographs. PATIENTS AND METHODS: We conducted a retrospective study of 47 patients who underwent maxillary advancement ±â€¯mandibular setback between 2006 and 2016. Preoperative and 1 year postoperative audio recordings were blinded for scoring by three trained speech therapists. Preoperative and 1 year postoperative lateral cephalometric radiographs were used to obtain information about skeletal movement and its relationship with the velopharyngeal area. Correlations between speech outcomes and cephalometric radiographs were determined. RESULTS: Hyponasality improved significantly after surgery (p < 0.05), whereas hypernasality deteriorated significantly only in patients who underwent maxillary advancement alone (p < 0.05). No difference in speech parameters was found between patients with hypernasality or patients who had a pharyngoplasty preoperatively and the rest of the group. No correlation was found between the amount of maxillary advancement and hypernasality. A significant correlation (r < -0.49, p < 0.05) was found between the preoperative velar length and hypernasality postoperatively. CONCLUSIONS: Maxillary advancement has a negative impact on velopharyngeal function, whereas bimaxillary surgery seems to protect from deterioration. No difference was found in the amount of maxillary advancement or in velopharyngeal measurements between the Le Fort I group and the bimaxillary group. A short soft palate is a predictor of hypernasality after orthognathic surgery.

Release of syngnathia by anticlockwise rotation and mandibular advancement using bilateral alloplastic temporomandibular joint prostheses: a new approach.

We describe a new approach to the planning of treatment and subsequent operation on a patient with syngnathia and severe mandibular retrognathism. To facilitate a large mandibular advancement we applied alloplastic temporomandibular joint (TMJ) prostheses to the coronoid processes after anticlockwise rotation of the mandible. To the best of our knowledge this is the first documented case of its kind.

Study of condylar positional changes after sagittal split osteotomy for mandibular advancement: A prospective cohort study.

PURPOSE: To analyse the possible morphologic and positional changes of the mandibular condyles after orthognathic surgery. MATERIAL AND METHODS: A prospective cohort study was performed. Patients with mandibular retrognathism were surgically treated to advance the mandible. The study group included seventeen patients (34 condyles) treated with sagittal split osteotomies alone (4 patients) or in combination with maxillary osteotomies (13 patients). Only condyles located on the mandibular side that advance during surgery were studied, therefore only 25 condyles entered this prospective study. Beside it, a group of 6 patients undergoing maxillary surgery as only procedure, maxillary group, was also studied to determinate the influence of maxillary surgery on condylar displacement. Computed tomographies and lateral cephalometric radiographs were performed two weeks before surgery and one year after the surgical procedures. Different variables which analyse the position and morphology of the mandible were studied. The data obtained were analysed statistically by computing R2 values. RESULTS: In the maxillary group they were small displacements in magnitude and not significant. In the study group, 8 condyles showed morphological changes with alteration on reference points. In the remainder 17 condyles different displacements were noted after surgery. Several of these positional changes were predictable and did not affect postoperative mandibular stability. CONCLUSIONS: condylar displacements that occur after sagittal split osteotomies for mandibular advancement show significant correlation with the degree of mandibular advancement and can be defined by mathematical formulae. Maxillary osteotomies do not seem to influence condylar position when bimaxillary procedures take place.

Growth and Development of Craniofacial Structures in Patients at Different Ages With Unrepaired Submucous Cleft Palate.

PURPOSE: Submucous cleft palate (SMCP) is a particular subtype of cleft palate deformity; research related to the craniofacial features of patients with SMCP is comparatively rare. The study objective was to perform a cephalometric comparison of the craniofacial features of patients with SMCP and non-cleft controls at different ages. MATERIALS AND METHODS: The sample in this cross-sectional study was composed of 2 groups: SMCP patients and non-cleft controls. The primary predictor variables were study group (cleft and non-cleft) and age. Age was divided into 3 groups. The outcome variables of interest were craniofacial measurements. The measurements used reflect cranial length, cranial angle, maxillary sagittal length and protrusion, maxillary vertical height, pharyngeal depth, facial height, mandibular length and protrusion, mandibular plane angle, and intermaxillary relation. Adjusted cephalometric craniofacial measurements between the groups were compared in 3 age groups using generalized linear models after being adjusted for age and gender. RESULTS: The study included 60 SMCP patients and 60 non-cleft controls. SMCP patients and non-cleft controls were divided into 3 subgroups: those aged 5 to 7 years, those aged 9 to 11 years, and those aged 18 to 30 years. Patients with SMCP at age 5 to 7 years showed a shortened cranial base length, maxillary sagittal length and height, and bony pharynx depth. Patients with SMCP at age 9 to 11 years showed a smaller maxillary sagittal length and bony pharynx depth and an inharmonious jaw relationship. Patients with SMCP at age 18 to 30 years showed a smaller maxillary sagittal length and height and an inharmonious jaw relationship. CONCLUSIONS: SMCP is associated with progressive maxillary retrognathism and reduced profile convexity from childhood to adulthood.

Determining the Patient-Specific Optimum Osteotomy Line for Severe Mandibular Retrognathia Patients.

PURPOSE: The purpose of this study is to suggest a patient-specific osteotomy line to optimize the distractor position and thus to minimize the disadvantages of conventional mandibular distraction osteogenesis (MDO) protocols. In addition, this study also aims to compare the conventional MDO protocols with the new MDO protocol proposed in this study in terms of both orthodontic outcomes and mechanical effects of osteotomy level on callus stabilization by means of the finite element method. METHODS: A preoperative patient-specific 3-dimensional bone model was created and segmented by using computed tomography images of an individual patient. Virtual orthodontic set-up was applied to the segmented model prior to the virtual surgery. In order to compare the proposed osteotomy line with the conventional lines used in clinical applications, virtual surgery simulations were performed and callus tissues were modelled for each scenario. The comparison of the success of each osteotomy line was carried out based on the occlusion of the teeth. RESULTS: The osteotomy line determined using the method proposed in this study has resulted in far less malocclusion than the conventional method. Namely, any angular deviation from the optimum osteotomy line determined in this study might result in deep-bite or open-bite. On the other hand, the finite element analysis results have indicated that this deviation also negatively affects the callus stability. CONCLUSION: In order to achieve a better MDO treatment in terms of occlusion of the teeth and the callus stability, the location of the osteotomy line and the distractor position can be computationally determined. The results suggest that MDO protocol developed in this study might be used in clinic to achieve a better outcome from the MDO treatment.

Are there risk factors for osseous mandibular inferior border defects after bilateral sagittal split osteotomy?

PURPOSE: Bone defects of the inferior mandibular border (osseous inferior border defects) can cause unesthetic postoperative outcomes after bilateral sagittal split osteotomy (BSSO). The aim of this study was to estimate the frequency of osseous inferior border defects after BSSO and to identify risk factors for this complication. MATERIALS AND METHODS: This retrospective study included consecutive patients who underwent BSSO for mandibular retrognathia. The primary outcome was the presence/absence of osseous inferior border defects. Predictors included the mandibular movement, rotation of the occlusal plane, postoperative proximal segment position, pattern of lingual fracture, occurrence of bad split, and presence of third molars. RESULTS: The study sample consisted of 200 patients and had a mean follow-up of 13 months. The mean mandibular advancement and rotation was respectively 5.8 mm and 5.4° clockwise. Osseous inferior border defects were present in 7.0% of splits and in 12.5% of patients. Significant risk factors for inferior border defects included increased advancement, increased clockwise rotation, cranial rotation of the proximal segment, and a split originating in the lingual cortex. CONCLUSION: In conclusion, osseous inferior border defects occur significantly more often in cases with large mandibular advancement, increased clockwise rotation of the occlusal plane, malpositioning of the proximal segment, and a split originating in the lingual cortex.

Risk factors related to aggressive condylar resorption after orthognathic surgery for females: retrospective study.

OBJECTIVE: The aim of the present study was to identify the risk factors for aggressive condylar resorption (ACR) after orthognathic surgery. METHODS: A total of 25 female patients with osteoarthritis (OA) scheduled for orthognathic surgery were divided into two groups: those who exhibited ACR (ACR (+), n = 8) and those who did not exhibit ACR (ACR (-), n = 17) after surgery. Clinical indices were used to determine the extent of mandibular advancement, the presence of temporomandibular disorder (TMD), and relevant medical treatment histories (including the use of oral contraceptive (OC) medication. TMJ dysfunction was clinically evaluated in terms of pain, the presence of sounds (clicks or crepitus), and disc displacement, joint effusion (JE), and synovial hyperplasia (SH); these were further investigated with the aid of magnetic resonance imaging (MRI). The cephalographic findings were compared with the normal profiles of Japanese subjects. RESULTS: The mean (with SD) extent of mandibular advancement was 11.4 mm (2.4) in ACR (+) and 4.1 mm (1.8) in ACR (-). The TMD medical history of ACR (+) was much more extensive than that of ACR (-); all patients in ACR (+) had a history of OC use. More patients in ACR (+) than in ACR (-) had TMJ dysfunction and disc displacement, JE, and SH on MRI. Preoperative cephalograms showed that ACR (+) patients exhibited counterclockwise rotation of the mandible and retrognathism that was attributable to a small sella-nasion-B (SNB) angle, a wide mandibular plane angle, and a negative inclination of the ramus. CONCLUSIONS: The present findings suggest that the development of ACR after orthognathic surgery to treat mandibular retrognathism may be associated with coexisting TMJ pathologic abnormality.

Timing of Surgical Removal of Odontoma in a Growing Orthodontic Patient: A Case Report.

In patients with skeletal malocclusion and odontoma, the prioritization of treatment is ofgreat importance. Ifsurgical removal of odontoma is postponed, the probability of adjacent teeth impaction increases. In this case, skeletal treatment was performed before odontoma rgery due to concerns about facial appearance and the patient's fear of surgery, and therefore adjacent tooth failed to erupt.

Study of Genial Tubercles of Craniofacial Anomalies Individuals on Cone Beam Computed Tomography Scans.

PURPOSE: Genial tubercles (GTs) are bony protuberances on the lingual aspect of the mandible symphysis, where genioglossus and geniohyoid muscles are inserted. In the literature, few papers report their real dimensions. Cleft lip and palate are craniofacial anomalies involving the maxilla, but the anatomical structures of the mandible can be altered when these have associated with the cleft, some syndrome. This study aimed to evaluate the GTs of 30 individuals and to make their measurements in cone beam computed tomography examinations. METHODS: A sample of 30 individuals, 19 of them with cleft lip and palate, 6 individuals with Treacher Collins syndrome (TCS), and 5 individuals with Pierre Robin sequence, was used. The GTs were evaluated about the amount and the following measurements were performed: A--distance from the apex of the central incisors to GT, B--mandibular thickness in the region of GT, C-GT height, D-GT width, and E--distance from inferior border of mandible to GT. RESULTS: The individuals presented since the absence of GTs to 3. The TCS group had the highest average of the measurements A, D, and E with statistical difference (P = 0.006) (P = 0.011) and (P = 0.017), respectively. The Pierre Robin sequence group had the highest average measurement of B and C, but there was no statistical difference. CONCLUSIONS: The difference in the measurements can be explained perhaps because individuals with TCS have glossoptosis and changes on retrognathic mandible, which would affect the position of the GT.

Unilateral and bilateral dental transpositions in the maxilla-dental and skeletal findings in 63 individuals.

AIM: This was to elucidate dental and skeletal findings in individuals with unilateral and bilateral maxillary dental transpositions. MATERIAL AND METHODS: The sample comprised of radiographic materials from 63 individuals with maxillary dental transpositions from the Departments of Odontology at the Universities of Copenhagen and Aarhus and by the Danish municipal orthodontic service. The cases were divided into three groups: unilateral transposition of the canine and first premolar (Type 1U), bilateral transposition of canine and first premolar (Type 1B), and unilateral transposition of canine and lateral incisor (Type 2). The dentitions were analysed regarding agenesis and dental morphological anomalies on panoramic radiographs, and craniofacial aspects were cephalometrically analysed on profile images The results were statistically evaluated. RESULTS: All groups demonstrated increased occurrences of agenesis (Type 1U and Type 1B: 31 agenesis in 15 patients; and Type 2 three agenesis in three patients). Taurodontic root morphology was most dominant in Type 1U. Peg-shaped lateral incisors showed an increased occurrence, though not in Type 1U. Skeletally, Type 1B and Type 1U demonstrated maxillary retrognathia (more pronounced in Type 1B). Type 2 showed a significant posterior inclination of the maxilla. CONCLUSION: Transpositions of maxillary canines involve dental and skeletal deviations. Dental deviations were predominantly taurodontic root morphology and agenesis. Regarding skeletal deviations, bilateral transpositions of the canines and the first premolars are associated with skeletal changes. Unilateral transpositions are possibly a localised deviation with minor or no skeletal involvements. The results indicate a possible difference in the aetiologies of unilateral and bilateral transpositions.

Influence of maxillary advancement surgery on skeletal and soft-tissue changes in the nose - a retrospective cone-beam computed tomography study.

OBJECTIVES: Surgical correction of skeletal maxillary retroposition is often associated with changes in the morphology of the nose. Unwanted alar flaring of the nose is observed in many cases. The aim of the present study was therefore to investigate the influence of surgical advancement of the maxilla on changes in the soft-tissue morphology of the nose. Having a coefficient that allows prediction of change in the nasal width in Caucasian patients after surgery would be helpful for treatment planning. MATERIALS AND METHODS: All 33 patients included in this retrospective study were of Caucasian descent and had skeletal Class III with maxillary retrognathia. They were all treated with maxillary advancement using a combination of orthodontic and maxillofacial surgery methods. Two cone-beam computed tomography (CBCT) datasets were available for all of the study's participants (16 female, 17 male; age 24.3 ± 10.4 years): the first CBCT imaging was obtained before the planned procedure (T0) and the second 14.1 ± 6.4 months postoperatively (T1). Morphological changes were recorded three-dimensionally using computer-aided methods (Mimics (Materialise NV, Leuven/Belgium), Geomagic (Geomagics, Morrisville/USA)). Statistical analysis was carried out using SPSS 21 for Mac. RESULTS: The mean sagittal advancement of the maxilla was 5.58 mm. The width of the nose at the alar base (Alb) changed by a mean of + 2.59 mm (±1.26 mm) and at the ala (Al) by a mean of + 3.17 mm (±1.32 mm). Both of these changes were statistically highly significant (P = 0.000). The increase in the width of the nose corresponded to approximately half of the maxillary advancement distance in over 80 % of the patients. The nasolabial angle declined by an average of -6.65° (±7.71°). CONCLUSIONS: Maxillary advancement correlates with a distinct morphological change in nasal width. This should be taken into account in the treatment approach and in the information provided to patients.

Anatomic study to determine a safe surgical reference point for mandibular ramus osteotomy.

OBJECTIVE: The purpose of this study was to identify a surgical reference point on the mandibular ramus that can be used during ramus osteotomy to prevent injury to the inferior alveolar nerve. MATERIALS AND METHODS: A total of 125 subjects' mandibles were analyzed and compared on a three-dimensional (3D) model constructed from computed tomography (CT). 25 volunteer subjects with normal class I occlusion (group I, control), 50 consecutive subjects (25 females and 25 males) diagnosed with mandibular retrognathism (group II), and 50 consecutive subjects (25 females and 25 males) with prognathism (group III) were included. This study created a landmark (the midwaist point) at the halfway point on a horizontal plane between the most concave points on the anterior and posterior borders of mandibular ramus, with the vertical plane bisecting the horizontal plane. The midwaist point was compared to other anatomic landmarks including antilingula, lingula, and mandibular foramen for correlation. RESULTS: The distance from the midwaist point to lingula and mandibular foramen along the horizontal plane was not significantly different among three groups. Lingula and mandibular foramen were mostly located within 2 mm posterior of the midwaist point, whereas the locations of lingula and mandibular foramen along the vertical plane to the midwaist point were highly variable. CONCLUSION: The midwaist point is an excellent intraoperative reference point that can help surgeons to identify the position of the lingual and the mandibular foramen, thus preventing inferior alveolar nerve injury.

A patient with severe maxillary gingival exposure treated with combined compression osteogenesis of the anterior alveolar bone and conventional Le Fort I osteotomy.

Excessive gingival exposure at the maxillary anterior region during not only smiling (a gummy face) but also at rest creates both functional and aesthetic problems for patients. We herein introduce a unique treatment procedure for mandibular retrognathia with a gummy face. This procedure combines conventional Le Fort I osteotomy and following corticotomy at the anterior region of the maxilla. Subsequently, the anterior segment is continuously compressed (compression osteogenesis) in a posterior-superior direction until it reaches an ideal position. This procedure appears to safely and adequately resolve both the aesthetic and functional complaints associated with patients with a gummy face.

3-dimensional facial simulation in orthognathic surgery: is it accurate?

PURPOSE: The purpose of this study was to measure the accuracy of 3D computer simulation of soft tissue changes after orthognathic surgery. MATERIALS AND METHODS: Consecutive patients who underwent orthognathic surgery were studied by photogrammetric facial scanning and cone-beam computed tomography before and after surgery. The photogrammetric scan was then fused to the cone-beam computed tomogram, creating a patient-specific image. The surgery was simulated in 3D form and the simulated soft tissue face was compared with the actual facial scan obtained 6 months postoperatively. Absolute millimeter differences between the simulated and actual postoperative changes in selected cephalometric skin markings were computed. RESULTS: The study was composed of 23 subjects (mean age, 31 yr; 13 women and 10 men). Eighteen different cephalometric landmarks were measured (total, 28). For 15 landmarks, the difference between actual and simulated measurements was smaller than 0.5 mm. Only 3 landmarks had a difference of 0.5 mm, and these were in the region of the labial landmarks. CONCLUSION: Based on the present study, 3-dimensional computer surgical simulation of the soft tissue of the face for routine orthognathic surgery is accurate enough for routine clinical use.