Analysis of the Relationship Between Micrognathia and Cleft Palate: A Systematic Review

Arthrogryposis multiplex congenita: dental and maxillofacial phenotype - A scoping review

INTRODUCTION

Arthrogryposis multiplex congenita (AMC) is a heterogeneous group of disorders associated with decreased fetal movement, with a prevalence between 1/3000 and 1/5200 live births. Typical features of AMC include multiple joint contractures present at birth, and can affect all joints of the body, from the jaw, and involving the upper limbs, lower limbs and spine. The jaws may be affected in 25 % of individuals with AMC, with limited jaw movement and mouth opening. Other oral and maxillofacial deformities may be present in AMC, including cleft palate, micrognathia, periodontitis and delayed teething. To our knowledge, oral and maxillofacial abnormalities have not been systematically assessed in individuals with AMC. Therefore, this scoping review was conducted to identify, collect, and describe a comprehensive map of the existing knowledge on dental and maxillofacial involvement in individuals with AMC.

METHODOLOGY

A scoping review was conducted in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews guidelines. The PRISMA guidelines for scoping reviews were followed and databases were searched for empirical articles in English and French published until October 2022. We searched MEDLINE, Embase, Web of Science and ERIC databases. Two authors independently reviewed the articles and extracted the data.

RESULTS

Of a total of 997 studies that were identified, 96 met the inclusion criteria and were subsequently included in this scoping review. These 96 studies collectively provided insights into 167 patients who exhibited some form of oral and/or maxillofacial involvement. Notably, 25 % of these patients were within the age range of 0-6 months. It is worth highlighting that only 22 out of the 96 studies (22.9 %), had the primary objective of evaluating dental and/or maxillofacial deformities. Among the patients studied, a prevalent pattern emerged, revealing that severe anomalies such as micrognathia (56 %), high-arched palate (29 %), cleft palate (40 %), limited mouth opening (31 %), and dental anomalies (28 %) were frequently observed. Importantly, many of these patients were found to have more than one of these anomalies. Even though these maxillofacial impairments are known to be associated with dental problems (e.g., cleft palate is associated with oligodontia, hypodontia, and malocclusion), their secondary effects on the dental phenotype were not reported in the studies.

CONCLUSION

Our findings have uncovered a notable deficiency in existing literature concerning dental and maxillofacial manifestations in AMC. This underscores the need for interdisciplinary collaboration and the undertaking of extensive prospective cohort studies focused on AMC. These studies should assess the oral and maxillofacial abnormalities that can impact daily functioning and overall quality of life.

Classification of Skeletal Phenotypes of Preadolescent Patients With Isolated Cleft Palate Using Principal Component Analysis and Cluster Analysis

This study aimed to classify the skeletal phenotypes of preadolescent patients with isolated cleft palate using principal component analysis and cluster analysis. Sixty-four preadolescent female patients with isolated cleft palate (incomplete hard palate and complete soft palate cleft group, n=51; complete cleft of the hard and soft palate group, n=13; the mean age when lateral cephalograms were taken, 7.08±0.76 y) were included. Ten angular and 2 ratio cephalometric variables were measured on a lateral cephalogram. Cluster analysis was performed using 3 representative variables obtained from principal component analysis (SN-GoMe, SNA, and SNB). The differences in the variables among the clusters were characterized using the Kruskal-Wallis test. As a result of the analysis, 6 clusters were obtained from 3 groups: the retrusive maxilla and mandible group: cluster 3 (14.1%, moderately hyperdivergent pattern), cluster 5 (17.2%, severely hyperdivergent pattern); the normal maxilla and mandible group: cluster 1 (23.4%, normodivergent pattern), cluster 4 (12.5%, moderately hyperdivergent pattern), cluster 6 (20.3%, severely hyperdivergent pattern); the normal maxilla and protrusive mandible group: cluster 2 (12.5%, normodivergent pattern). The distribution of isolated cleft palate types did not differ among the 6 clusters ( P >0.05). Two thirds of the patients (68.7%, clusters 1, 2, 4, and 6) had a normal anteroposterior position of the maxilla, while one third of the patients (31.3%, clusters 3 and 5) showed a retrusive mandible. These results indicate that isolated cleft palate patients have diverse maxillo-mandibular growth patterns compared with patients with cleft lip and palate.

Dental management of a patient with Moebius syndrome: A case report

BACKGROUND

Moebius syndrome (MBS) is a nonprogressive and rare congenital neuromuscular disorder involving the facial nerve and abductor nerve; it mainly manifests as facial paralysis and eye strabismus paralytic symptoms. Tissues in the oral cavity are also compromised, characterized by microstomia, micrognathia, tongue malformation, cleft lip, high arched palate or cleft palate, bifid uvula, and dental malocclusion. Therefore, dentistry plays a fundamental and crucial role in caring for these individuals. However, there is limited available data on MBS treatment, particularly regarding dental management.

CASE SUMMARY

This case report presents dental treatment of a 21-year-old man with MBS and discusses crucial interactions among oral complications of MBS. In this case, the patient was clinically characterized by congenital neuromuscular disorder, occlusal disorders, and tooth and gum problems. It is noteworthy that the patient presented early eruption of deciduous teeth 2 mo after birth, which has not been reported in other MBS cases and suggests a potentially new clinical manifestation of this syndrome. It is important to note that MBS cannot be cured, and oral manifestations of this syndrome can be managed by a multidisciplinary health care team that helps the patient maintain oral hygiene and dental health. After a series of oral treatments, no obvious poor oral hygiene, swollen gums, or abnormal imaging results were observed after 2 years of follow-up.

CONCLUSION

This case addressed the oral clinical manifestations of MBS and difficulties experienced during dental management, and suggested early tooth eruption as a potentially new clinical manifestation of this syndrome. Knowledge of the loop-mediated association among oral complications of this syndrome is essential to perfecting treatments.

Maxillary Arch Dimensions in 6-Year-Old Cleft Children in Northern Finland: A Cross-Sectional Study

The aim was to cross-sectionally examine the maxillary arch dimensions in 6-year-old children with cleft lip and/or palate and to compare them with the initial cleft sizes among patients with cleft palate. The study included 89 patients with clefts treated at the Oulu University Hospital. The subjects were divided into three groups: cleft palate, cleft lip, and cleft lip and palate. Study casts were scanned, and the maxillary arch dimensions were examined using a 3D program (3Shape Orthoanalyzer, Copenhagen, Denmark). The statistical methods Student's t-test and one-way ANOVA were used to compare the means (SD) between the groups. Spearman's correlation coefficient was used to determine the correlation between cleft severity and maxillary dimensions. A significant difference was found between different initial cleft sizes in terms of distance between the second deciduous molar and the first incisor on the right side. The intermolar width showed a negative correlation with the initial cleft size. The dimensions were shorter for clefts affecting the palate and largest for clefts affecting only the lip. Larger clefts resulted in a shorter maxilla on the right side. Many dimensions became shorter when the initial cleft was larger. Clefts of the palate resulted in smaller maxillas.

Fetal micrognathia in the first trimester: An ominous finding even after a normal array

OBJECTIVE

To evaluate the prognosis of fetuses with a prenatal diagnosis of micrognathia in the first trimester.

STUDY DESIGN

Over a 3-year period, patients with fetal micrognathia were detected at the time of nuchal translucency screening. The medical records of these pregnancies were reviewed, including maternal demographics, sonographic findings, genetic testing results and pregnancy outcomes.

RESULTS

Forty-three cases of first-trimester micrognathia were included in this study. Chromosomal abnormalities were detected in seven cases. Of the fetuses with a normal array, further investigation of monogenic disorders with whole-exome sequencing was undertaken in 13 cases. Monogenic syndromes were identified in eight cases, including six with de-novo dominant alleles and two with recessive conditions. Whole-exome sequencing was refused in 23 cases; among these, other additional anomalies were found on anatomic ultrasound in 10 cases.

CONCLUSION

This study demonstrated that caution should be adopted when finding an apparently isolated micrognathia in early gestation, even with a normal array. A diagnosis of genetic syndrome or multiple anomalies on subsequent scans is most likely, and will affect the final prognosis.

Three-dimensional reconstruction of systematic histological sections: application to observations on palatal shelf elevation

Normal mammalian secondary palate development undergoes a series of processes, including palatal shelf (PS) growth, elevation, adhesion and fusion, and palatal bone formation. It has been estimated that more than 90% of isolated cleft palate is caused by defects associated with the elevation process. However, because of the rapidly completed elevation process, the entire process of elevation will never be easy to clarify. In this article, we present a novel method for three-dimensional (3D) reconstruction of thick tissue blocks from two-dimensional (2D) histological sections. We established multiplanar sections of the palate and tongue in coronal and sagittal directions, and further performed 3D reconstruction to observe the morphological interaction and connection between the two components prior to and during elevation. The method completes an imaging system for simultaneous morphological analysis of thick tissue samples using both synthetic and real data. The new method will provide a comprehensive picture of reorientation morphology and gene expression pattern during the palatal elevation process.

Characteristics of craniofacial morphology and factors affecting them in patients with isolated cleft palate

Background

Myriad maxillo-mandibular occlusal relationships are observed in patients with isolated cleft palate (ICP), unlike in patients with other cleft types, such as cleft lip and palate.

Objectives

This study aimed to categorise the characteristics of craniofacial morphology in patients with ICP, and investigate the clinical factors affecting these categorised morphological characteristics.

Methods

Thirty-six girls with ICP (age (mean ± SD): 5.36 ± 0.36 years) underwent cephalometric measurement. Their craniofacial morphology was categorised using cluster analysis. Profilograms were created and superimposed onto the standard Japanese profilograms to visualise the morphological characteristics of each group (cluster). The mean values and variations in the linear and angular measurements of each group were compared with the Japanese standards and statistically analysed using Dunnett’s test after the analysis of variance. Fisher’s exact test was used to analyse the differences between the cleft types (cleft in the hard and/or soft palate) and skills of the operating surgeons in the groups.

Results

Cluster analysis of craniofacial morphologies in patients with ICP resulted in the formation of three categories: the first cluster exhibited a relatively harmonious anteroposterior relationship between the maxilla and the mandible (22.2%); the second cluster exhibited crossbite owing to a significantly smaller maxilla (33.3%); and the third cluster exhibited a smaller mandible with posterior rotation showing skeletal class II malocclusion (44.4%). Differences in cleft types and surgeons were not associated with the distribution of patients in each cluster.

Conclusions

Patients with ICP exhibited characteristic morphological patterns, such as bimaxillary retrusion or severe mandibular retrusion, besides the anterior crossbite frequently found in patients with cleft lip and palate . Understanding the typical morphological characteristics could enable better diagnostic categorisation of patients with ICP, which may eventually improve orthodontic treatment planning.

Clinical outcomes of prenatal diagnosis of the fetal micrognathia: A case report

RATIONALE

Micrognathia is a subtle facial malformation characterized by a small mandible and receding chin. Fetal micrognathia is often associated with chromosomal abnormalities, skeletal dysplasia, and various syndromes. Once it is dignosised, detailed fetal malformation screening and chromosome examination should be carried out.

PATIENT CONCERN

One pregnant woman with suspicion of fetal micrognathia was referred from her local hospital to our hospital for detailed fetal malformation screening and fetal echocardiography. Examination of the fetus was performed using a two-dimensional and three-dimensional ultrasound probe in multiple planes. The fetus showed micrognathia without glossoptosis with features of the inferior facial angle (IFA) ≤50° and his tongue reached anterior mandibular border box during normal movement.

DIAGNOSES

The fetus was diagnosed as isolated micrognathia prenatally without multisystem abnormalities.

INTERVENTIONS

Amniocentesis was performed and the fetus was found to carry 46XN with 6q14.1 duplication, the significance of which was unclear.

OUTCOMES

The fetus was labored through vagina at 38 weeks gestation. A small soft cleft palate was diagnosed after delivery.

LESSONS

This case suggests that once prenatal diagnosis of the fetal micrognathia has been made, we should carefully examine the presence of fetus's multisystem developmental abnormalities and due consideration should be given for associated soft cleft palate.

The ontogeny of Robin sequence

The triad of micrognathia, glossoptosis, and concomitant airway obstruction defined as "Robin sequence" (RS) is caused by oropharyngeal developmental events constrained by a reduced stomadeal space. This sequence of abnormal embryonic development also results in an anatomical configuration that might predispose the fetus to a cleft palate. RS is heterogeneous and many different etiologies have been described including syndromic, RS-plus, and isolated forms. For an optimal diagnosis, subsequent treatment and prognosis, a thorough understanding of the embryology and pathogenesis is necessary. This manuscript provides an update about our current understanding of the development of the mandible, tongue, and palate and possible mechanisms involved in the development of RS. Additionally, we provide the reader with an up-to-date summary of the different etiologies of this phenotype and link this to the embryologic, developmental, and genetic mechanisms.

Pathogenesis of Cleft Palate in Robin Sequence: Observations From Prenatal Magnetic Resonance Imaging

PURPOSE

The etiology of the palatal cleft in Robin sequence (RS) is unknown. The purpose of this study was to assess the position of the fetal tongue at prenatal magnetic resonance imaging (MRI) and to suggest a potential relation between tongue position and development of the cleft palate seen in most patients with RS.

MATERIALS AND METHODS

This is a retrospective case-and-control study including fetuses with prenatal MRIs performed in the authors' center from 2002 to 2017. Inclusion criteria were 1) prenatal MRI of adequate quality, 2) liveborn infant, and 3) postnatal diagnosis of RS (Robin group) or cleft lip and palate (CLP group). Patients with postnatal RS without a palatal cleft were excluded. A control group with normal facial morphology was matched by gestational age. The outcome variable was tongue position at fetal MRI, described as within the cleft, along the floor of the mouth (normal), other, or indeterminate.

RESULTS

One hundred twenty-two patients with mean gestational age at MRI of 25.8 ± 4.9 weeks were included (Robin, n = 21 [17%]; CLP, n = 47 [39%]; control, n = 54 [44%]). The tongue was visualized within the palatal cleft in 76.2% of the Robin group and 4.3% of the CLP group. The tongue was found along the floor of the mouth (normal) in the remainder of the Robin and CLP groups and in 100% of the control group.

CONCLUSION

These findings suggest a relation between in utero tongue position and the development of cleft palate in RS.

Dislocated Tongue Muscle Attachment and Cleft Palate Formation

In Pierre Robin sequence, a retracted tongue due to micrognathia is thought to physically obstruct palatal shelf elevation and thereby cause cleft palate. However, micrognathia is not always associated with palatal clefting. Here, by using the Bmp7-null mouse model presenting with cleft palate and severe micrognathia, we provide the first causative mechanism linking the two. In wild-type embryos, the genioglossus muscle, which mediates tongue protrusion, originates from the rostral process of Meckel's cartilage and later from the mandibular symphysis, with 2 tendons positive for Scleraxis messenger RNA. In E13.5 Bmp7-null embryos, a rostral process failed to form, and a mandibular symphysis was absent at E17.5. Consequently, the genioglossus muscle fibers were diverted toward the lingual surface of Meckel's cartilage and mandibles, where they attached in an aponeurosis that ectopically expressed Scleraxis. The deflection of genioglossus fibers from the anterior-posterior toward the medial-lateral axis alters their direction of contraction and necessarily compromises tongue protrusion. Since this muscle abnormality precedes palatal shelf elevation, it is likely to contribute to clefting. In contrast, embryos with a cranial mesenchyme-specific deletion of Bmp7 (Bmp7:Wnt1-Cre) exhibited some degree of micrognathia but no cleft palate. In these embryos, a rostral process was present, indicating that mesenchyme-derived Bmp7 is dispensable for its formation. Moreover, the genioglossus appeared normal in Bmp7:Wnt1-Cre embryos, further supporting a role of aberrant tongue muscle attachment in palatal clefting. We thus propose that in Pierre Robin sequence, palatal shelf elevation is not impaired simply by physical obstruction by the tongue but by a specific developmental defect that leads to functional changes in tongue movements.