The cell surface hyaluronidase TMEM2 plays an essential role in mouse neural crest cell development and survival.

Hyaluronan (HA) is a major extracellular matrix component whose tissue levels are dynamically regulated during embryonic development. Although the synthesis of HA has been shown to exert a substantial influence on embryonic morphogenesis, the functional importance of the catabolic aspect of HA turnover is poorly understood. Here, we demonstrate that the transmembrane hyaluronidase TMEM2 plays an essential role in neural crest development and the morphogenesis of neural crest derivatives, as evidenced by the presence of severe craniofacial abnormalities in Wnt1-Cre-mediated Tmem2 knockout (Tmem2CKO) mice. Neural crest cells (NCCs) are a migratory population of cells that gives rise to diverse cell lineages, including the craniofacial complex, the peripheral nervous system, and part of the heart. Analysis of Tmem2 expression during NCC formation and migration reveals that Tmem2 is expressed at the site of NCC delamination and in emigrating Sox9-positive NCCs. In Tmem2CKO embryos, the number of NCCs emigrating from the neural tube is greatly reduced. Furthermore, linage tracing reveals that the number of NCCs traversing the ventral migration pathway and the number of post-migratory neural crest derivatives are both significantly reduced in a Tmem2CKO background. In vitro studies using Tmem2-depleted mouse O9-1 neural crest cells demonstrate that Tmem2 expression is essential for the ability of these cells to form focal adhesions on and to migrate into HA-containing substrates. Additionally, we show that Tmem2-deficient NCCs exhibit increased apoptotic cell death in NCC-derived tissues, an observation that is corroborated by in vitro experiments using O9-1 cells. Collectively, our data demonstrate that TMEM2-mediated HA degradation plays an essential role in normal neural crest development. This study reveals the hitherto unrecognized functional importance of HA degradation in embryonic development and highlights the pivotal role of Tmem2 in the developmental process.

The significant role of glycosaminoglycans in tooth development.

This review delves into the roles of glycosaminoglycans (GAGs), integral components of proteoglycans, in tooth development. Proteoglycans consist of a core protein linked to GAG chains, comprised of repeating disaccharide units. GAGs are classified into several types, such as hyaluronic acid, heparan sulfate, chondroitin sulfate, dermatan sulfate, and keratan sulfate. Functioning as critical macromolecular components within the dental basement membrane, these GAGs facilitate cell adhesion and aggregation, and play key roles in regulating cell proliferation and differentiation, thereby significantly influencing tooth morphogenesis. Notably, our recent research has identified the hyaluronan-degrading enzyme Transmembrane protein 2 (Tmem2) and we have conducted functional analyses using mouse models. These studies have unveiled the essential role of Tmem2-mediated hyaluronan degradation and its involvement in hyaluronan-mediated cell adhesion during tooth formation. This review provides a comprehensive summary of the current understanding of GAG functions in tooth development, integrating insights from recent research, and discusses future directions in this field.

Three-dimensional changes in the cranial base associated with soft-diet feeding.

BACKGROUND: Masticatory activity affects the morphology of the maxillo-mandibular complex, however, its influence on the cranial base remains to be elucidated. The recent integration of quantitative morphometric analysis with 3D imaging enabled a comprehensive and high-resolution morphological characterization of the craniofacial complex. We aimed to investigate the influence of masticatory activity on the morphology of the growing cranial base by three-dimensional (3D) geometric morphometric approach using micro-CT. METHODS: The micro-CT data was reanalyzed to illustrate the 3D shape of the cranial base, and wireframe models were generated by connecting landmarks on the images. In the original study, mice were fed a soft diet (SD) of powdered pellets or a conventional hard diet (HD) for 6 weeks from 3 to 9 weeks of age, immediately after weaning. A principal component (PC) analysis analyzed shape variations and assessed their significance, while canonical variate (CV) analysis facilitated the comparison and differentiation of groups based on shape, unveiling meaningful shape distinctions. RESULTS: Three PCs were extracted that significantly separated the SD and HD groups among those explaining variations in shape. These PCs were related to the length of the sphenoid bone, the width of the anterior part of the sphenoid bone, and the length of the cranial base. Furthermore, one CV effectively distinguished SD from HD, and CV analysis showed that the sphenoid was shortened in the length and narrowed at the border of the temporal bone in SD mice. CONCLUSIONS: Masticatory loading affects the skeletal development of the cranial base. The morphology of the sphenoid bone was affected in both the sagittal and transverse axes.

Synergistic role of retinoic acid signaling and Gata3 during primitive choanae formation.

Developmental defects of primitive choanae, an anatomical path to connect the embryonic nasal and oral cavity, result in disorders called choanal atresia (CA), which are associated with many congenital diseases and require immediate clinical intervention after birth. Previous studies revealed that reduced retinoid signaling underlies the etiology of CA. In the present study, by using multiple mouse models which conditionally deleted Rdh10 and Gata3 during embryogenesis, we showed that Gata3 expression is regulated by retinoid signaling during embryonic craniofacial development and plays crucial roles for development of the primitive choanae. Interestingly, Gata3 loss of function is known to cause hypoparathyroidism, sensorineural deafness and renal disease (HDR) syndrome, which exhibits CA as one of the phenotypes in humans. Our model partially phenocopies HDR syndrome with CA, and is thus a useful tool for investigating the molecular and cellular mechanisms of HDR syndrome. We further uncovered critical synergy of Gata3 and retinoid signaling during embryonic development, which will shed light on novel molecular and cellular etiology of congenital defects in primitive choanae formation.

Craniofacial and dental characteristics of three Japanese individuals with genetically diagnosed SATB2-associated syndrome.

Craniofacial defects are one of the most frequent phenotypes in syndromic diseases. More than 30% of syndromic diseases are associated with craniofacial defects, which are important for the precise diagnosis of systemic diseases. Special AT-rich sequence-binding protein 2 (SATB2)-associated syndrome (SAS) is a rare syndromic disease associated with a wide variety of phenotypes, including intellectual disability and craniofacial defects. Among them, dental anomalies are the most frequently observed phenotype and thus becomes an important diagnostic criterion for SAS. In this report, we demonstrate three Japanese cases of genetically diagnosed SAS with detailed craniofacial phenotypes. The cases showed multiple dental problems, which have been previously reported to be linked to SAS, including abnormal crown morphologies and pulp stones. One case showed a characteristic enamel pearl at the root furcation. These phenotypes add new insights for differentiating SAS from other disorders.

Prognostic Factors for Orthognathic Surgery in Children With Cleft Lip and/or Palate: Dentition and Palatal Morphology.

To determine dental and palatal morphology in children with cleft lip and/or palate (CL/P) and identify morphological prognostic factors for orthognathic surgery (OGS).Retrospective cohort study.Orthodontic department of a university dental hospital.This study included 80 patients with bilateral and unilateral CL/P who had lateral cephalograms at the ages of 7 (T1), 15 (T2) years, and a dental plaster model at T1.Plaster models at T1 were scanned with a three-dimensional (3D) scanner. Morphological features were extracted from 3D models with geometric morphometrics software as principal components (PCs). The combinations of the PCs and other predictive factors (ie, the No. of clefts in the lip and alveolus, the palatal repair method, sex, cephalometric variables at T1, and the No. of missing teeth) were examined by logistic regression to determine the predictability for OGS. The need for OGS and skeletal and dental discrepancies at T2 were examined as outcomes.Shrinkage of the palate, including vertical shallowing and transverse narrowing of the posterior maxilla and cleft-side asymmetry of the anterior maxilla at T1, as well as the No. of clefts in the lip and alveolus, the palatal repair method, male sex, several cephalometric variables for the sagittal and vertical dimensions, and the No. of missing teeth, were found to be predictive factors for OGS.Morphological prognostic factors for OGS in children with CL/P were determined.

Relationship Between Stigma Experience and Self-Perception Related to Facial Appearance in Young Japanese Patients with Cleft lip and/or Palate.

OBJECTIVE: To examine the relationship between stigma experience related to facial appearance in Japanese youths with cleft lip and/or palate (CL/P) and their self-perception. DESIGN: A cross-sectional study. PARTICIPANTS: Sixty-nine Japanese youths with CL/P (11-18 years old). OUTCOME MEASURES: The participants' stigma experience in relation to facial appearance (measured with 7 single contextual scale items) and their self-perception (measured with 5 domain scores based on 30 perceptual items) were assessed using the Japanese version of the Youth Quality of Life Instrument-Facial Differences Module. Participants were categorized into high and low self-perception subgroups with a threshold of 1 standard deviation for each domain. The frequency of stigma experiences was compared between the following 2 subgroups: age, sex, cleft palate only versus other cleft, and high versus low self-perception. Correlations between the responses regarding stigma and all domain scores were examined. RESULTS: Sixteen percent of the participants reported experiencing stigma. Hearing others say something about their face occurred significantly more frequently in youths 15 to 18 years of age than in youths 11 to 14 years of age. Stigma frequency was not found to differ by sex or cleft type. Stigma experiences were significantly more frequent for youth with higher scores across negative self-perception domains as well as higher coping skills. Significant correlations were identified between responses regarding stigma items and all domain scores (r = 0.27-0.63, p < .05). CONCLUSIONS: It was found that stigma experiences related to facial appearance may influence negative self-perceptions of facial differences as well as higher coping skills among Japanese youths with CL/P.

Orthodontic Management of Severe Hypodontia and Impacted Maxillary Second Molars in a Patient with Sotos Syndrome.

Sotos syndrome is a genetic disorder characterized by distinct craniofacial features, overgrowth in childhood, and impaired intellectual development. We herein report the successful orthodontic treatment of a 14-year-old boy with Sotos syndrome caused by a heterozygous mutation in the NSD1 gene. He showed severe hypodontia, impaction of the maxillary second molars and a skeletal Class III jaw-base relationship. Orthodontic management, including space control by protraction of the maxillary first molars and traction of the impacted molars, was performed using fixed appliances and miniscrews. As a result, acceptable occlusion was obtained without any discernible relapse 18 months postretention.

Morphologic variations in the craniofacial structures in Japanese adults and their relationship with sex differences.

INTRODUCTION: The morphology of the human face varies broadly, with genetic and environmental factors determining these variations. Examining variations in the 3-dimensional (3D) craniomandibular morphology and identifying related factors (eg, sex differences) are important in orthodontic clinics. This study observed shape variations in the 3D facial morphology of Japanese adults showing skeletal Class 1 malocclusion and examined the association of sexual dimorphism with shape variations. METHODS: Sixty cone-beam computed tomography images of Japanese adults (30 males and 30 females) with skeletal Class I malocclusion were employed. In each cone-beam computed tomography image, wire mesh fitting was conducted as previously described. A principal component (PC) analysis after Procrustes registration and the PC clustering method was conducted to observe the shape variations. A PC regression analysis was conducted to determine the sexual morphologic characteristics. RESULTS: Nine PCs depicting 62% of the morphology were determined. Four typical phenotypes were found, mainly related to mandibular protrusion (PC1) and the vertical divergence of the face (PC2). PCs related to sex determination were PC3 (robustness of the mandibular angle in males), PC5 (greater size and shape of the coronoid and mastoid processes in males), and PC7 (greater maxillary width in males), accounting for 16% of total variations. CONCLUSIONS: The major shape variations in skeletal Class 1 subjects were related to nonsexual dimorphic characteristics (ie, mandibular protrusion and facial divergence). Sexual dimorphic characteristics were evaluated in detail and accounted for 16% of total morphologic variations.

The Association Between Runx Signaling and Craniofacial Development and Disease.

PURPOSE OF REVIEW: The Runx family genes (Runx1, Runx2, Runx3, and Cbfb) are important transcriptional regulators in the development of various tissues. We herein highlight the roles of the Runx family genes in morphogenesis in the craniofacial regions and in the pathogenesis of congenital morphological problems in these regions. RECENT FINDINGS: A recent analysis using conditional Runx mutant animals and a human genetic study identified the novel roles of Runx genes in the development of the tooth, salivary glands, and the palate. In an animal study, Runx1/Cbfb signaling was found to regulate the Lgr5 expression and maintain the stem cells in the dental epithelium in the growing incisors. Aberrant Runx1/Cbfb signaling induced male-specific involution of the convoluted granular cell differentiation of the submandibular gland. In palatogenesis, Runx1/Cbfb signaling regulated the Tgfb3 expression in the fusing palatal epithelium through Stat3 activation. The combination of a human genetic study and a phenotype analysis of mutant animals revealed the various roles of Runx genes in the development of the tooth, palate, and salivary glands. Runx genes have functional redundancy in various tissues, which still hinder the roles of Runx genes in morphogenesis. Future studies may reveal the novel roles of Runx signaling.

Comparison of 3-D mandibular surfaces generated by MRI and CT.

OBJECTIVE: The purpose of this study was to evaluate the errors of three-dimensional mandibular surfaces generated using magnetic resonance imaging (MRI) when computed tomography (CT) was set as the gold standard. SETTINGS AND SAMPLE POPULATION: Seven patients with orthognathic deformities who had undergone CT and MRI scans were included in the study. MATERIALS AND METHODS: Mandibular surfaces were generated on each CT and MR image by the surface-rendering method. Intra-individual reliability between CT and MRI was statistically tested by the confidence limits of agreement (LOA) for systematic error, 95% confidence interval minimal detectable change (MDC95 ) for random error and intra-class correlation coefficient (ICC). RESULTS: The average total error was 1.6 mm. The greatest MDC95 was observed in the coronoid region in all directions. The other regions showed MDC95 values of < 1.8 mm (transvers direction), 3.5 mm (vertical direction) and 1.7 mm (antero-posterior direction). ICCs showed 'almost perfect' agreement with respect to all regions. CONCLUSION: Random errors were quantified for 3-D rendering of the mandible from MRI data. Although the coronoid region showed the greatest errors, the other regions of the mandibular surfaces generated using MRI were able to be evaluated.

Prosthetic and orthodontic rehabilitation of a patient with severe maxillary central incisor root resorption associated with impacted maxillary canines.

OBJECTIVE: This case report describes the orthodontic and prosthetic rehabilitation of a patient with resorption of the roots of the maxillary central incisors due to the ectopic maxillary canines. CLINICAL CONSIDERATIONS: A 16-year-old woman presented with severe resorption of the roots of the maxillary central incisors due to the ectopic maxillary canines. The impacted canines were orthodontically tracted with a lingual arch-supporting temporary central incisors and vertical elastics, and, undesirable root proximity was later corrected by moving the canines distally 1.5 mm apart. Gingival replacement cords were placed into the gingival sulcus of the canines, and tooth preparation was performed along with rotary gingival curettage of the interdental papilla. Convex form was provided for the mesial and labio-distal subgingival contour of the restorations. CONCLUSIONS: The creeping attachment of the interdental papilla was successfully achieved by the orthodontic arrangement of interdental distance and the prosthetic stimulus via the retraction cord, rotary curettage, and convex mesial subgingival contours. In addition, selective retraction of the labio-distal gingiva by overcontoured restorations moved the gingival zenith position (GZP) distally. Finally, the canine crown morphology and gingival level mimicked the central incisors. CLINICAL SIGNIFICANCE: This clinical report introduces a treatment workflow of to recover the esthetic disturbance due to severe root resorption of the maxillary central incisors associated with impacted maxillary canines. The present orthodontic and prosthetic procedure can improve both hard and soft tissue esthetics and could be used in similar cases, such as malformed teeth and tooth autotransplantation or transposition with disturbances in the interdental papilla height or the GZP.

Evaluation of Facial Appearance-Related Quality of Life in Young Japanese Patients With Cleft Lip and/or Palate.

OBJECTIVE: (1) To confirm the reliability of a Japanese version of the Youth Quality of Life Instrument-Facial Differences Module (YQOL-FD); (2) to assess the quality of life (QoL) related to facial difference in Japanese youths with cleft lip and/or palate (CL/P) using this instrument; and (3) to examine the QoL differences according to age, sex, and cleft type. DESIGN: A cross-sectional study. SETTING: Japanese youths with CL/P were recruited through our hospital and asked to complete the YQOL-FD. PARTICIPANTS: Sixty-nine Japanese youths (age, 11-18 years) with CL/P. OUTCOME MEASURES: The domain scores of stigma, negative consequences, negative self-image, positive consequences, and coping in the YQOL-FD, and the reliability of such scores were evaluated. RESULTS: The instrument showed an acceptable internal consistency (Cronbach α = 0.74-0.92) and test-retest reliability (intraclass correlation coefficient = 0.94-0.98), except for the coping domain. The individual's domain scores were spread out from the lowest score to the high scores among all domains, thus indicating the negative and positive impacts of living with facial differences regarding their QoL may vary among individuals with CL/P. All domain scores in the 15- to 18-year-old group were significantly higher than those in 11- to 14-year-old group; there were no significant differences according to sex or cleft type. CONCLUSIONS: The instrument showed acceptable reliability, except for the coping domain. There were individual variations in QoL concerning the facial difference among Japanese youths with CL/P as measured by the YQOL-FD, suggesting the importance of individual evaluations. Perceptions were influenced by age, but not sex or cleft type.

Comparison of clinical outcomes between Invisalign and conventional fixed appliance therapies in adult patients with severe deep overbite treated with nonextraction.

INTRODUCTION: The use of aligner therapy for orthodontic treatment has increased substantially in the past decade. However, no study has compared treatment outcomes between the conventional fixed appliance and Invisalign therapies in patients with a severe deep overbite. METHODS: This study included 50 consecutive adult patients who underwent treatment with either Invisalign (n = 25; mean age, 23.3 ± 8.5 years) or a conventional fixed appliance (n = 25; mean age, 23.1 ± 6.5 years) to correct overbite >5 mm and >60% deep overbite. Cephalometric analysis and peer assessment rating was used to compare the clinical outcome between groups. RESULTS: Cephalometric analysis showed significant differences in N-Me (P = 0.0005) and Mp-L6 (P = 0.0001) between Invisalign and fixed appliance treatment groups. No significant differences were observed in the peer assessment rating analysis or total treatment duration between the 2 groups. CONCLUSIONS: Both Invisalign and conventional fixed appliances were effective in treating patients with a severe deep overbite. Invisalign therapy may be preferable over conventional fixed appliance therapy in patients with high angle and deep overbite. However, because this study had a retrospective design, the results should be viewed with caution.

The validation of orthodontic artificial intelligence systems that perform orthodontic diagnoses and treatment planning.

AIM: This study was aimed to evaluate two artificial intelligence (AI) systems that created a prioritized problem list and treatment plan, and examine whether the performance of the aforementioned systems was equivalent to orthodontists. MATERIALS AND METHODS: A total of 967 consecutive cases [800: training; 67: validation; 100: evaluation (40: randomly selected for the clinical evaluation)] were used. We used a stored document that describes (1) the patient's clinical information, (2) the prioritized list, and (3) a treatment strategy without digital tooth movement. Sentences of (1) were vectorized according to the bag of words method (V); sentences of (2) and (3) were relabelled with 423 and 330 labels, respectively. AI systems that output labels for the prioritized list (subtask 1) and treatment planning (subtask 2) based on the vectors V were developed using a support vector machine and self-attention network, respectively, while the system was trained to improve precision and recall. Clinical evaluations were conducted by four orthodontists (no faculty or residents; peer group) in two sessions: in the first session, peer group and the developed AI systems created problem lists and treatment plans; in the second session, two of the peer group (not AI) evaluated these lists and plans, including the lists and plans of the AIs, by scoring them using 4-point scales [unacceptable (1) to ideal (4)]. Scores were compared among the system and peer group (Wilcoxon signed-rank test, P < 0.05). RESULTS: The precision after system training was 65% and 48% for subtasks 1 and 2 respectively, with recall of 55% and 48%, respectively. The clinical evaluation of the AI system for subtask 1 showed a mid-rank. For subtask 2, the AI system had a significantly lower score than the three panels but the same rank with one panel. CONCLUSIONS: Two AI systems that output a prioritized problem list and create a treatment plan were developed. The clinical system ability of the former system showed a mid-rank in the peer group, and the latter system was almost equivalent to the worst orthodontist.

Determination of prognostic factors for orthognathic surgery in children with cleft lip and/or palate.

OBJECTIVE: To determine the prognostic factors for orthognathic surgery (OGS) in children with cleft lip and/or palate (CL/P) using artificial intelligence (AI) systems. DESIGN: Retrospective cohort study. SETTING: An orthodontic department at a university dental hospital. PARTICIPANTS: This study included 126 patients with bilateral and unilateral CL/P for whom lateral cephalograms were obtained at three time points: 7 (T1), 10 (T2) and 15 (T3) years of age. MAIN OUTCOME MEASURES: Cleft type, severity of lip separation at birth, number of missing teeth, sex, palatal repair methods and surgeons, cephalometric variables at T1 and T2, and the total duration of orthodontic treatment were examined as predictors. The need for OGS and skeletal and dental discrepancies at T3 was examined as outcomes. RESULTS: A total of six models were developed, with a mean area under the receiver operating characteristic curve of 0.93. Multiple prognostic factors for OGS were identified. In particular, the number of clefts in the lip and alveolus showed relatively high odds ratios, as did anterior crossbite at T3. Achieving palatal closure with the push-back method, rather than Furlow's method, was also found to be a predictive factor for anterior crossbite at T3, with high odds ratios. CONCLUSIONS: The prognostic factors for OGS determined by the AI systems were the number of clefts in the lip and alveolus, the palatal repair method, male sex, several cephalometric variables for the sagittal and vertical dimensions, growth patterns and the number of missing teeth.

Clinical applicability of automated cephalometric landmark identification: Part II - Number of images needed to re-learn various quality of images.

AIM: To estimate the number of cephalograms needed to re-learn for different quality images, when artificial intelligence (AI) systems are introduced in a clinic. SETTINGS AND SAMPLE POPULATION: A total of 2385 digital lateral cephalograms (University data [1785]; Clinic F [300]; Clinic N [300]) were used. Using data from the university and clinics F and N, and combined data from clinics F and N, 50 cephalograms were randomly selected to test the system's performance (Test-data O, F, N, FN). MATERIALS AND METHODS: To examine the recognition ability of landmark positions of the AI system developed in Part I (Original System) for other clinical data, test data F, N and FN were applied to the original system, and success rates were calculated. Then, to determine the approximate number of cephalograms needed to re-learn for different quality images, 85 and 170 cephalograms were randomly selected from each group and used for the re-learning (F85, F170, N85, N170, FN85 and FN170) of the original system. To estimate the number of cephalograms needed for re-learning, we examined the changes in the success rate of the re-trained systems and compared them with the original system. Re-trained systems F85 and F170 were evaluated with test data F, N85 and N170 from test data N, and FN85 and FN170 from test data FN. RESULTS: For systems using F, N and FN, it was determined that 85, 170 and 85 cephalograms, respectively, were required for re-learning. CONCLUSIONS: The number of cephalograms needed to re-learn for images of different quality was estimated.

Clinical applicability of automated cephalometric landmark identification: Part I-Patient-related identification errors.

OBJECTIVES: To determine whether AI systems that recognize cephalometric landmarks can apply to various patient groups and to examine the patient-related factors associated with identification errors. SETTING AND SAMPLE POPULATION: The present retrospective cohort study analysed digital lateral cephalograms obtained from 1785 Japanese orthodontic patients. Patients were categorized into eight subgroups according to dental age, cleft lip and/or palate, orthodontic appliance use and overjet. MATERIALS AND METHODS: An AI system that automatically recognizes anatomic landmarks on lateral cephalograms was used. Thirty cephalograms in each subgroup were randomly selected and used to test the system's performance. The remaining cephalograms were used for system learning. The success rates in landmark recognition were evaluated using confidence ellipses with α = 0.99 for each landmark. The selection of test samples, learning of the system and evaluation of the system were repeated five times for each subgroup. The mean success rate and identification error were calculated. Factors associated with identification errors were examined using a multiple linear regression model. RESULTS: The success rate and error varied among subgroups, ranging from 85% to 91% and 1.32 mm to 1.50 mm, respectively. Cleft lip and/or palate was found to be a factor associated with greater identification errors, whereas dental age, orthodontic appliances and overjet were not significant factors (all, P < .05). CONCLUSION: Artificial intelligence systems that recognize cephalometric landmarks could be applied to various patient groups. Patient-oriented errors were found in patients with cleft lip and/or palate.

Camouflage Treatment for Skeletal Maxillary Protrusion and Lateral Deviation with Classic-Type Ehlers-Danlos Syndrome.

We herein report the case of a 19-year-old female with a transverse discrepancy, skeletal Class II malocclusion, severe crowding with concerns of classic-type Ehlers-Danlos syndrome (EDS), aesthetics problems and functional problems. The main characteristics of classic EDS are loose-jointedness and fragile, easily bruised skin that heals with peculiar "cigarette-paper" scars. The anteroposterior and transverse skeletal discrepancies can generally be resolved by maxilla repositioning and mandibular advancement surgery following pre-surgical orthodontic treatment. However, this patient was treated with orthodontic camouflage but not orthognathic surgery because of the risks of skin bruising, poor healing and a temporomandibular disorder. A satisfactory dental appearance and occlusion were achieved after camouflage treatment with orthodontic anchor screws and the use of Class II elastics, including the preservation of the stomatognathic functions. Acceptable occlusion and dentition were maintained after a two-year retention period. This treatment strategy of orthodontic camouflage using temporary anchorage, such as anchor screws and Class II elastics, may be a viable treatment option for skeletal malocclusion patients with EDS.

Comprehensive Orthodontic Treatment of a Patient With Prader-Willi Syndrome.

Prader-Willi syndrome (PWS) is a rare genetic disorder caused by a defect in paternally expressed genes in the 15q11-q13 region. Prader-Willi syndrome affects many parts of the body and involves craniofacial and dentofacial abnormalities. We herein report the successful 2-stage orthodontic treatment of an 8-year-old girl with PWS caused by paternal 15q11-q13 deletion. She presented with a skeletal class II relationship with mandibular deviation, a deep overbite, and severe crowding of the lower dental arch. Functional appliance therapy was utilized to improve her skeletal discrepancy. The second phase of orthodontic treatment using fixed appliances was started at 14.5 years old, which improved her remained crowding and large overbite. As a result, her facial appearance and occlusion were improved without any discernible relapse after 2 years of retention. We describe the outcomes of orthodontic treatment for a patient with PWS and discuss the specific attention during orthodontic treatment.