Soft-tissue, non-osteogenic distraction of the mandible and lower face in bilateral hemifacial microsomia-technical report.

The aim of this study is to present a sequential strategy of soft-tissue, non-osteogenic distraction with a novel device, followed by microvascular bony reconstruction for severe cases of mandibular hypoplasia. The case of a 21-year-old woman with Goldenhar syndrome is presented, whose mandible remained severely hypoplastic despite previous attempts at distraction and was not suitable for further osteogenic distraction. Soft tissue deficiency and pin track scarring prevented free fibular transfers. A personalized distractor, anchored to the cranium and the mandibular symphysis, was designed to expand the soft tissues while allowing for physiological temporomandibular joint (TMJ) movement without compression forces. Internal distractors were placed along the osteotomies to prevent condylar luxation. After completion of the soft tissue distraction, the native mandible was resected except for the condyles and reconstructed with two free fibula flaps. This report represents the proof of concept of a sequential approach to severe lower face soft-tissue and bone deficiency, which preserves TMJ function and avoids the transfer of poorly matched skin to the face.

Three-dimensional measurements of symmetry for the mandibular ramus.

BACKGROUND: The study examines a sample of patients presenting for viscerocranial computer tomography that does not display any apparent signs of asymmetry, assesses the three-dimensional congruency of the mandibular ramus, and focuses on differences in age and gender. METHODS: This cross-sectional cohort study screened viscerocranial CT data of patients without deformation or developmental anomalies. Segmentations were obtained from the left and right sides and superimposed according to the best-fit alignment. Comparisons were made to evaluate three-dimensional congruency and compared between subgroups according to age and gender. RESULTS: Two hundred and sixty-eight patients were screened, and one hundred patients met the inclusion criteria. There were no statistical differences between the left and right sides of the mandibular ramus. Also, there were no differences between the subgroups. The overall root mean square was 0.75 ± 0.15 mm, and the mean absolute distance from the mean was 0.54 ± 0.10 mm. CONCLUSION: The mean difference was less than one millimetre, far below the two-millimetre distance described in the literature that defines relative symmetry. Our study population displays a high degree of three-dimensional congruency. Our findings help to understand that there is sufficient three-dimensional congruency of the mandibular ramus, thus contributing to facilitating CAD-CAM-based procedures based on symmetry for this specific anatomic structure.

Helical distraction is superior to linear and circular distraction in mandibular distraction osteogenesis: an in silico study.

Helical mandibular distraction is theoretically better than linear or circular distraction. However, it is not known whether this more complex treatment will result in unquestionably better outcomes. Therefore, the best attainable outcomes of mandibular distraction osteogenesis were evaluated in silico, given the constraints of linear, circular, and helical motion. This cross-sectional kinematic study included 30 patients with mandibular hypoplasia who had been treated with distraction, or to whom this treatment had been recommended. Demographic information and the computed tomography (CT) scans showing the baseline deformity were collected. The CT scans of each patient were segmented and three-dimensional models of the face created. Then, the ideal distraction outcomes were simulated. Next, the most favorable helical, circular, and linear distraction movements were calculated. Finally, errors were measured: misalignment of key mandibular landmarks, misalignment of the occlusion, and changes in intercondylar distance. Helical distraction produced trivial errors. In contrast, circular and linear distractions resulted in errors that were statistically and clinically significant. Helical distraction also preserved the planned intercondylar distance, while circular and linear distractions led to unwanted changes in the intercondylar distance. It is now evident that helical distraction offers a new strategy to improve the outcomes of mandibular distraction osteogenesis.

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.

Severity of Mandibular Dysmorphology in Treacher Collins Syndrome for Stratification of Perioperative Airway Risk.

BACKGROUND: Patients with Treacher Collins syndrome (TCS) and attendant airway dysmorphology may be predisposed to airway complications in the perioperative period. However, limited data correlates severity of mandibular hypoplasia and airway status. This study aims to improve risk stratification for perioperative airway insufficiency in TCS by using a previously proposed mandibular severity index. METHODS: Patient demographics, perioperative airway status, difficulty of intubation, and Cormack Lehane grade were collected and compared using a TCS mandibular hypoplasia severity grading scale in patients with TCS treated between 2000 and 2022. RESULTS: Twenty-six patients underwent 222 procedures with institutional mandibular severity gradings as follows: 23% Grade I, 31% Grade II, 39% Grade III, 8% Grade IV. Our severity index was associated with intubation difficulty ( P <0.001) and difficult airway status ( P <0.001), with 72% of difficult airways found in grade III and grade IV patients. Mandibular retrusion and ramal hypoplasia subscores were positively correlated with measures of airway severity ( P <0.001), whereas the gonial angle was negatively correlated ( P <0.001). Age was negatively correlated with difficult visualization for endotracheal intubation ( P =0.02) but had no association with difficult airway status ( P =0.2). CONCLUSIONS: This study found a positive correlation between severity of maxillomandibular dysmorphology and perioperative airway difficulty in TCS patients. Our findings suggest that severely affected patients require heightened vigilance throughout life, as difficult airways may not completely resolve with aging. Given the risk of morbidity and mortality associated with airway complications, proper identification and preparation for challenging airways is critical for TCS patients.

[Lower jawbone structures symmetry evaluation using cone beam computed tomography]. / Otsenka simmetrichnosti kostnykh struktur nizhnei chelyusti po dannym konusno-luchevoi komp'yuternoi tomografii.

OBJECTIVE: To assess the prevalence and quantitative characteristics of skeletal asymmetries of the body and lower jaw branches in three-dimensional space. MATERIALS AND METHODS: Using depersonalized data archive, of 400 CBCT scans, forty studies were picked randomly. Patients aged 25 to 35 years participated in research, no history of maxillofacial reconstructive surgery; gender, race, and facial anomaly were ignored. Three experienced doctors, independently, identified 15 reference points on radiographic images of AUTOPLAN software. Expert consensus found in the orientation determination. Six planes and eight points were constructed, using Math algorithms and the Python OOP; body and branches of the lower jaw length measurements performed and processed automatically. RESULTS: The study identified symmetry, using a method for determining parameters of the lower jaw in 3D space (Priority Reference No.2023100466 at 10.01.2023), modern dentistry research method. Both sides of data obtained shown asymmetry of the body and branches of the lower jaw occurred in 45% (18 people) and 67.5% (27 people) of cases. Forty percent of cases were noted with Mild asymmetry of the lower jaw body (16 people), moderate asymmetry noted in 5% (2 people). These parameters were 57.5% for branches, (23 people) and 10% (4 people). Combined form of anomaly observed in 37.5% (15 people) of cases, among which 12 people (75%) showed adaptive compensation of anomalies, which requires further investigation on a larger number of patients. CONCLUSION: Lower body jaw asymmetry is prevalent (80%). Patients with moderate and serious anomaly form appeared in 15% of cases.

[Surgical treatment of a patient with mandibular micrognathia accompanied by obstructive sleep apnea syndrome using extended genioplasty]. / Khirurgicheskoe lechenie patsienta s mikrognatiei nizhnei chelyusti i sindromom obstruktivnogo apnoe vo sne metodom rasshirennoi genioplastiki.

A method for diagnosing, planning and surgical treatment of patients with micrognathia of the mandible with physiological occlusion is proposed, which makes it possible to objectively assess the severity of the anomaly and concomitant functional disorders of external respiration in the nasopharynx and oropharynx, as well as to identify the pathophysiological mechanisms of obstructive sleep apnea syndrome (OSAS) and develop an optimal surgical treatment plan with high functional and aesthetic results.

The Outcome of Mandibular Distraction Osteogenesis in Infants with Severe Pierre Robin Sequence in Vietnam.

The purpose of this study was to provide the experience of a single center with mandibular distraction osteogenesis (MDO) in Pierre Robin Sequence (PRS) patients. A longitudinal research analysis was conducted to identify PRS patients who underwent MDO at Vietnam National Children's Hospital between 2019 and 2021. The following criteria were used to determine inclusion: 1) those pediatric patients with PRS who were not well handled with conservative therapy, 2) those who received MDO with internal mandibular distractors, and 3) no previous treatment elsewhere. Demographic data, postoperative complications, and surgical results were all evaluated. The inclusion criteria were met by 73 patients. There were no difficulties associated with our distraction strategy. The majority of individuals with tracheostomies were successfully decannulated, and the remainder were able to avoid tracheostomies. Using MDO in PRS is an effective technique to avoid future airway issues. The success rate was lower and the complication rate higher for patients who had a tracheotomy before distraction and for those who underwent distraction at an age older than 2 months. The presence of laryngomalacia, gastric reflux disease, cardiac abnormalities, and GI anomalies did not increase the likelihood of MDO failure in PRS patients.

Tracheostomy, the Not So Definitive Airway?: Tracheostomy Morbidity in Pediatric Craniofacial Patients.

BACKGROUND: Tracheostomy is the definitive treatment for airway management in severe cases of craniofacial-associated upper airway obstruction, like the Pierre-Robin sequence, but is associated with significant morbidity. The purpose of this study was to examine tracheostomy-associated morbidities and mortalities in craniofacial patients to identify opportunities to improve clinical care and patient prognosis. METHODS: The study was a retrospective review of pediatric craniofacial patients who were tracheostomized between 2016 and 2022. Data regarding their demographics, craniofacial diagnoses, endoscopic airway anomalies, intubation grade of view classification, tracheostomy-related complications, and causes of mortality were analyzed. RESULTS: Sixteen of the 17 tracheostomized pediatric patients had the Pierre-Robin sequence, with 5 of those patients having an additional syndromic craniofacial diagnosis. Additional airway anomalies were found in 82.4% of the patients. The mean length of hospital stay after tracheostomy was 4.08 months. Infection was the most common complication, observed in 94.1% of patients, followed by stomal granulation in 76.5% of patients. Two mortalities were observed: one following the compassionate removal of ventilator support and the other following the accidental dislodgment of the tracheostomy tube. CONCLUSIONS: Tracheostomy-related complications were observed in all craniofacial patients in this group. Compared with the general pediatric population, tracheostomized craniofacial patients may endure longer hospital stays and greater stomal granulation rates. Mandibular distraction osteogenesis may allow for tracheostomy avoidance in these patients, and future research should focus on comparing the long-term complication rates and outcomes between tracheostomy mandibular distraction osteogenesis in this challenging patient population.

Morphological integration in inferior alveolar canal and mandibular shapes.

OBJECTIVE: During embryogenesis of mandible, the initial ossification centre begins at the bifurcation of the inferior alveolar (IA) and the mental nerves. Additionally, in congenital anomalies like craniofacial microsomia (CFM), the IA canal is completely absent on the microsomic side. These observations led us to hypothesise that there may be a morphological integration between these structures - the IA nerve and the mandibular shapes. Therefore, the primary objective of this study was to test for morphological integration between these structures and the secondary objective was to determine if there were shape variations in these structures among skeletal Classes I, II and III subjects. SETTING AND SAMPLE POPULATION: The sample size of the study is 80 full-head cone-beam computed tomography (CBCT) scans (age 16-56 years). METHODS: We retrieved CBCT scans from our archived database using specific inclusion/exclusion criteria. In the de-identified CBCT scans, traditional coordinate landmarks and sliding semi-landmarks were placed on the mandible and the IA canal (proxy for IA nerve). Using geometric morphometric analyses, we tested integration between the IA canal and the mandibular shapes. We used Procrustes ANOVA to test for overall shape variations among the three skeletal classes (Classes I, II and III). RESULTS: The IA canal and posterior/inferior border of mandible showed strong integration (r-PLS = .845, P = .001). Similar strong integration was also observed between the IA canal and the overall shape of the mandible (r-PLS = .866, P = .001). Additionally, there was a statistically significant variation in overall shape between skeletal Class I and Class II (P = .008) and Class II and Class III (P = .001). CONCLUSIONS: The strong integration between two structures suggests that the IA nerve may play a role in establishing mandibular shape early in development. We posit this may be important in driving mandibular defects seen in CFM, which warrants further investigation.

[Sequential treatment of oral and maxillofacial deformities with hemifacial microsomia].

The incidence of the first and second branchial arch syndrome namely hemifacial microsomia (HFM) is the second only to cleft lip and palate, and it is a very common craniofacial developmental deformity. This congenital condition affects the development of the orbit, ear, and mandible, and the clinical manifestations of each patient are significantly heterogeneous. Clinical treatment needs to formulate corresponding treatment measures according to different degrees of tissue deformity at different ages. This article puts forward personal suggestions for the sequential treatment of oral and maxillofacial deformities of HFM from the perspective of patient age and classification.

Feeding Outcomes After Mandibular Distraction for Airway Obstruction in Infants.

Robin sequence is a congenital issue resulting in airway obstruction, difficulty feeding, and failure to thrive. Mandibular Distraction Osteogenesis is used to improve airway obstruction in these patients, but little data exists characterizing feeding outcomes following surgery. This study aims to evaluate feeding outcomes and weight gain following mandibular distraction for airway correction in infants. A single-center retrospective chart review was conducted, and patients under 12 months old who underwent mandibular distraction between December 2015 and July 2021 were included in the study. The presence of cleft palate, distance of distraction, and polysomnography results were recorded. The primary outcomes were the length of distraction, need for nasogastric tube or G-tube at discharge, time lapsed to achieve full oral feeds, and weight gain (kilogram). Ten patients met the criteria. Of those 10 patients, 4 were syndromic, 7 had a cleft palate, and 4 had a congenital cardiac diagnosis. The average length of stay postsurgery was 28 days. Eight patients achieved full oral feeds in an average of 65.6 days. Five patients required nasogastric tube or G-tube at discharge, with 3 of these patients later transitioning to full oral feeds. All patients gained weight 3 months postsurgery with an average of 0.521 kg/mo. Patients who achieved full oral feeds gained an average of 0.549 kg/mo. Patients with supplementation gained an average of 0.454 kg/mo. All patients demonstrated improvement in airway obstruction with an average postoperative apnea hypopnea index of 1.64. Further investigation is necessary to identify challenges seen in feeding after mandibular distraction osteogenesis and improve care.

Himi-Lengthening Genioplasty: A Modified Technique for the Correction of Mandibular Asymmetry.

Mandibular asymmetry is among the most common facial anomalies. Traditionally, mandibular asymmetry with malocclusion has been treated with orthognathic surgery and genioplasty. However, routine genioplasty cannot achieve a satisfactory contour. Hence, this study presents a modified technique, himi-lengthening genioplasty, to resolve this matter. By combining this technique with orthognathic surgery, the authors successfully corrected mandibular asymmetry in 1-stage surgery, achieved ideal occlusion, and reconstructed the esthetic contour. No complications occurred during the 6-month follow-up period. Therefore, the authors recommend our modified surgical technique for its effectiveness, security, stability, and simplicity.

Craniofacial Microsomia: New Updates in Spinal Anomalies.

INTRODUCTION: Craniofacial microsomia (CFM) involves anomalies of the first and second pharyngeal arches, mainly of the mandible, maxilla, ears, and vertebral spine. This study aimed to identify the frequency and morphology of spinal anomalies of individuals with clinical diagnoses of CFM. In addition, the correlation between spinal anomalies and craniofacial involvement was performed. MATERIALS AND METHODS: This study was a retrospective review of individuals with a clinical diagnosis of craniofacial microsomia. The inclusion criteria were a clinical diagnosis of CFM with no overlap with any other syndromes of first and second pharyngeal arches and radiograph availability in the hospital's database. Prevalence and morphology of spinal anomalies were calculated and clinical details were recorded: types of spinal anomalies and correlations according to OMENS score. RESULTS: The sample consisted of 46 individuals with a clinical diagnosis of CFM, 24 (52,2%) female and 22 (47,8%) male (1M:1F). Twenty-one (45,7%) had unilateral craniofacial involvement and 25 (54,3%), bilateral. Twenty-eight (60,9%) individuals presented spinal anomalies. Those with unaltered spinal morphology showed a slight preference toward OMENS scores under 5: 7 patients did, only one of which had spinal alterations (14,3%); 68,8% (22) in the group with scores 5 to 9 (n=32) and 71,4% (5) in the 10 to 15 group (n=7) did as well. DISCUSSION AND CONCLUSIONS: Spinal anomalies in individuals with CFM are more common than usually reported in medical literature, mainly when associated with radial anomalies and correlate with statistical significance to facial features, mainly the OMENS score.

Is a Difficult Airway Team Needed for Intubation at Removal of Mandibular Distraction Devices for Infants With Robin Sequence?

PURPOSE: Difficult airway teams (DATs) are typically present to assist intubation at the initial mandibular distraction osteogenesis (MDO) operation for infants with Robin sequence (RS). In some institutions, the RS diagnosis triggers a "difficult airway" label for the infant, requiring DAT presence for future operations. By the time of distractor removal, however, breathing and airway anatomy are significantly improved. The objective of this study was to measure intubation difficulty and perioperative respiratory complications at MDO device removal as a proxy for the necessity for coordination with a DAT. METHODS: This is a retrospective study including infants with RS from 2013 to 2021 who had MDO during infancy. Patients were excluded if they had a tracheostomy or MDO device failure. Predictor variables included demographic data, comorbidities, and apnea-hypopnea indices (AHIs) from pre- and immediate post-MDO polysomnograms. The primary outcome measures were number of intubation attempts, laryngoscopy grade, and perioperative respiratory events at the distractor removal operation. Descriptive statistics were computed including Fisher's exact, paired sample t-tests, and Wilcoxon rank tests, and P < .05 was considered statistically significant. RESULTS: The sample included 47 (60% male) patients with a mean age at MDO of 12.0 ± 15.7 weeks. Significant improvement in AHI was seen after MDO (pre-MDO: 26.8 ± 18.4 events/hour; post-MDO 2.78 ± 2.66 events/hour; P < .001). Average number of intubation attempts decreased from 2.09 ± 1.36 to 1.30 ± 0.75 (P < .001) and the most common post-MDO laryngoscopy grade was 1 (69%). There were no intraoperative and 2 (4%) minor postoperative respiratory events, both in patients with repaired congenital cardiac disease and not related to traumatic intubation. CONCLUSION: Neither difficult intubations nor perioperative respiratory events associated with intubation trauma were seen at distractor removal, suggesting that specialty airway assistance is not routinely needed after successful MDO. DAT presence should be determined on a case-by-case basis based on specific patient risk factors.

Orthomorphic surgery for correction of mandibular dysmorphology post TMJ ankylosis. A report of 4 cases and review of literature / Cirugía ortomórfica para la corrección de la dismorfología mandibular posterior a la anquilosis de la ATM. Un informe de 4 casos y revisión de la literatura

La dismorfología mandibular es predominantemente el resultado de una deficiencia o exceso de crecimiento no coordinado. La anquilosis unilateral de la articulación temporomandibular durante la fase de crecimiento activo, si no se opera, produce cambios en el tamaño y la forma de la mandíbula y las estructuras circundantes. El uso de la cirugía ortognática para corregir las deformidades faciales que surgen de las discrepancias en las relaciones espaciales, aunque bien aceptado, no puede corregir las anomalías que surgen de una morfología alterada. La corrección quirúrgica utilizando principios ortomórficos restaura la morfología sin cambiar el estado oclusal, lo que demuestra ser una adición invaluable al repertorio de un cirujano maxilofacial.Cuatro pacientes previamente operados por anquilosis unilateral de la articulación temporomandibular que presentaban asimetría mandibular fueron tratados mediante corrección ortomórfica. El factor etiológico en todos los pacientes reclutados fue un traumatismo en la articulación temporomandibular durante la infancia. Los pacientes fueron evaluados para cambios neurosensoriales, evaluación de la apertura bucal antes y después de la cirugía, evaluación postoperatoria de la simetría mandibular y complicaciones postoperatorias al 3.er día, 3 semanas y 3 meses después de la cirugía. Se observó una buena a moderada corrección de la asimetría en todos los casos. Se observó parestesia del nervio mentoniano en un paciente. No se observaron complicaciones postoperatorias.La técnica descrita se puede utilizar como complemento de la cirugía ortognática convencional o como una alternativa de tratamiento de una sola etapa confiable para entidades dismórficas complejas. (AU)

Mandibular dysmorphology is predominantly a result of uncoordinated growth deficiency or surfeit. Unilateral temporomandibular joint ankylosis during the active growth phase, if left unoperated, brings about changes in the size and shape of the mandible and the surrounding structures. The use of orthognathic surgery in correcting the facial deformities arising from discrepancies in spatial relationships although well accepted is unable to correct anomalies arising from an altered morphology. The surgical correction using orthomorphic principles restore the morphology without changing the occlusal status, thus proving to be an invaluable addition to a maxillofacial surgeon’s repertoire.Four patients previously operated on for unilateral temporomandibular ankylosis having mandibular asymmetry were managed by orthomorphic correction. The etiological factor in all the recruited patients was trauma to the temporomandibular joint during childhood. The patients were evaluated for neurosensory changes, assessment of mouth opening before and after surgery, postoperative assessment of mandibular symmetry, and postoperative complications on 3rd day, 3 weeks, and 3 months postoperatively. Good to moderate asymmetry correction was seen in all the cases. Mental nerve paraesthesia was noted in one patient. No postoperative complications were noted.The described technique can be used as a complement to conventional orthognathic surgery or as a reliable single-stage treatment alternative for complex dysmorphic entities. (AU)

Application of Computer-Assisted Preoperative Planning in Treating Congenital Bilateral Zygomatico-Maxillo-Mandibular Fusion: A Case Report and Literature Review.

Congenital fusion of the jaws (syngnathia) is a rare facial malformation with an unknown etiology. This disease may vary in severity with adhesion of soft tissue and bony fusion. It can be anterior fusion, unilateral or bilateral fusion, and complete fusion. The main problem of these patients is the difficulty of airway maintenance and feeding, and the most common postoperative complication is the relapse of bony fusion. Here, we report a young male patient with bony syngnathia, involving bilateral fusion of the ascending ramus and body of the mandible with the maxillary complex. We performed bone isolation by computer-assisted preoperative planning and used an insertional temporalis flap to fix the wound surface to prevent refusion of bone.

Hemifacial microsomia is linked to a rare homozygous variant V162I in FRK and validated in zebrafish.

OBJECTIVES: Hemifacial microsomia (HFM) is a common birth defect involving the first and second branchial arch derivatives. Although several chromosomal abnormalities and causal gene variants have been identified, genetic etiologies in a majority of cases with HFM remain unknown. This study aimed to identify genetic mutations in affected individuals with HFM. METHODS: Whole-exome sequencing and bioinformatics analysis were performed for 16 affected individuals and their family members. Sanger sequencing was applied for confirmation of selected mutations. Zebrafish embryos were used for in situ hybridization of candidate gene, microinjection with antisense morpholino, and cartilage staining. RESULTS: A homozygous missense mutation (c.484G > A; p.V162I) in the FRK gene was identified in an 18-year-old girl with HFM and dental abnormalities. Heterozygous mutation of this mutation was identified in her parents, who are first cousins in a consanguineous family. FRK is highly expressed in the Meckel's cartilage during embryonic development in mouse and zebrafish. Knockdown of frk in zebrafish showed a lower length and width ratio of Meckel's cartilage, abnormal mandibular jaw joint, and disorganized ceratobranchial cartilage and bone. CONCLUSIONS: We identified a recessive variant in the FRK gene as a novel candidate gene for a patient with HFM and mandibular hypoplasia and revealed its effects on craniofacial and embryonic development in zebrafish.

Mandibular morphology and distraction osteogenesis vectors in patients with Robin sequence.

The aims of this cohort study were to compare the mandibular morphology between patients with Robin sequence (RS) and controls, and to examine the effects of mandibular distraction osteogenesis (MDO) using different vectors. Measurements of the mandibles of 80 patients with RS and 46 controls aged< 90 days were made using computed tomography. The data were compared among isolated RS patients (n = 58), syndromic RS patients (n = 22), and controls. Patients with RS exhibited significantly shorter ramus and body lengths and larger symphyseal angles than controls (all P < 0.001). Patients with isolated RS had shorter body lengths (P < 0.001), while syndromic patients had shorter ramus and body lengths (both P < 0.001) than controls. Seventy RS patients underwent MDO. Pre-MDO (n = 37) and post-MDO (n = 29) mandibular measurements were compared between patients undergoing MDO with a vertical vector and those undergoing MDO with a horizontal vector. Polysomnography data from part of the cohort highlighted the effectiveness of both vectors. MDO with a horizontal vector conferred 11% and 36% increases in ramus and body length, respectively, while these increases were 34% and 27.5%, respectively, with a vertical vector. MDO with a vertical vector was effective in lengthening ramus and body components and should be considered in the presence of ramus hypoplasia.

Congenital mandibular coronoid process hyperplasia and associated diseases.

Coronoid process hyperplasia (CPH) is an oral and maxillofacial surgical disease that can result in restricted jaw movement due to an enlarged and elongated mandibular coronoid process. It is characterized by the painless progressive restriction of unilaterally or bilaterally mouth opening. Clinically, unexplained bilateral CPH is less common and therefore often overlooked or misdiagnosed, and coronoidectomy can be very effective on improving mouth opening. Currently, the exact etiology and mechanism of congenital CPH have not yet been fully understood, but it is generally believed to be genetically related. In this paper, the relationship of the congenital mandibular CPH with the related diseases was examined based on cases collected in our clinic and literature review for the clinical diagnosis and treatment of patients with restricted mouth opening associated with CPH.