Genetic background of supernumerary teeth

A novel APC mutation associated with Gardner syndrome in a Chinese family

Gardner syndrome (GS) is a specific form of familial adenomatous polyposis (FAP), which manifests as colorectal polyps, multiple osteomas and soft tissue tumors, and in the oral cavity as osteomas of the jaws, odontomas, and abnormal tooth counts. The underlying cause of GS is attributed to mutations in the APC gene. Mutations in this gene disrupt the normal functioning of the protein and lead to the development of GS. To further investigate GS, a family affected by the syndrome was selected from Dongguan, Guangdong Province. The family members underwent a comprehensive survey, which involved collecting clinical data and peripheral venous blood samples. The samples were then used for genetic analysis. Whole exome sequencing (WES) and Sanger sequencing techniques were utilized to screen and identify specific mutation sites in the APC gene. The clinical findings for the GS family included the presence of gastrointestinal polyps and odontomas. After analyzing the genetic sequencing results, a novel mutation site c.4266dupA on the APC gene was found in the patients, which leading to the APC protein truncation. As a result of this study, it is suggested that odontoma may be an early indicator of GS. Additionally, the identification of this novel mutation site in the APC gene expands the known spectrum of genetic mutations associated with the disease. This discovery has significant implications for the early diagnosis of GS, thus enabling timely intervention to reduce the risk of developing colon cancer and other related diseases.

Management of a supernumerary tooth fused to the labial surface of a permanent maxillary central incisor

Key Clinical Message

Management of supernumerary teeth fused to the labial surface of permanent maxillary central incisors would require a multidisciplinary approach comprising of endodontic treatment, periodontal recontouring, and cosmetic composite restoration.

Abstract

The reported cases of supernumerary teeth fused to the labial surface of maxillary central incisors are rare. Such cases need multidisciplinary approaches. Herein, management of a supernumerary tooth fused to the labial surface of a maxillary central incisor is reported. Due to the presence of a communication path between the root canal systems of the two fused teeth, root canal therapy was performed first for the maxillary left central incisor and the supernumerary tooth. The crown of the supernumerary tooth was then removed in a surgical setting while preserving the root to maintain the thin covering of alveolar bone and prevent future periodontal problems. Subsequently, an esthetic composite restoration was performed.

Geminated Supernumerary Premolar Impacted in the Palate: A Report of a Rare Case and Review of the Literature

Supernumerary teeth are dental anomalies characterized by the presence of an excessive number of teeth in relation to normal dentition. Among these, the supernumerary premolars have a prevalence of 0.29% to 0.64%, making it a very rare finding. On the other hand, gemination is a developmental disturbance in the shape of the teeth where a partial cleavage of a single tooth germ results in the formation of a singular root and a singular pulp chamber but two partially or totally separated crowns. Although these anomalies as individual entities are fairly common in clinical practice, the occurrence of both anomalies in a single tooth is an extremely rare occurrence. We hereby report a rare case of impacted geminated supernumerary premolar in a 45-year-old female patient. A thorough search of the literature revealed that only four cases listing this anomaly have been reported in the literature thus deserving a mention. In addition to the case presentation, the authors have also reviewed the existing literature on this anomaly.

Analysis of Health Profile and Treatment Needs of Patients with Special Health Care Needs at a Malaysian Teaching Hospital: A 6-Year Observation

Aims and Objectives

Special care dentistry (SCD) provides oral health care to disabled individuals in an environmental, cultural or social setting that supports their oral health. This study aimed to analyze the profiles of patients managed at an SCD clinic in a teaching hospital based on their sociodemographic background, medical condition or disability, dental diagnosis and treatment provided.

Materials and Methods

This retrospective audit study included patients seen from the clinic's inception in January 2017 until June 2022, retrieved from the faculty's record management system. The pattern of patients seen was arranged on an Excel sheet and analyzed using SPSS. Quantitative data were analyzed via descriptive analysis (frequency) and chi-square test (P < 0.05).

Results

A 220% surge in the number of patients treated between January 2017 and June 2022, from two to 91 years old, with more male patients seen. Most patients had an intellectual disability (49.7%), followed by medical compromised (16.4%) and genetic conditions or syndromes (12.0%). 43% of had caries, which is more prevalent in women, and 31.6% had periodontal disease, with the majority being between the ages of 21 and 40. Periodontal treatment accounted for most of the dental treatment (76.1%). Even though only a small percentage of endodontic therapy was performed (2.4%), a significant association was found between the treatment, gender and age group of patients seen in the clinic.

Conclusion

Considering their health profile, oral diagnosis and therapy, this study demonstrated the varied sorts of patients encountered in an SCD specialist clinic. This useful information will be beneficial in the development of a comprehensive care dentistry center for this community.

Plasticity of Dental Cell Types in Development, Regeneration, and Evolution

Recent years have improved our understanding of the plasticity of cell types behind inducing, building, and maintaining different types of teeth. The latest efforts were aided by progress in single-cell transcriptomics, which helped to define not only cell states with mathematical precision but also transitions between them. This includes new aspects of dental epithelial and mesenchymal stem cell niches and beyond. These recent efforts revealed continuous and fluid trajectories connecting cell states during dental development and exposed the natural plasticity of tooth-building progenitors. Such "developmental" plasticity seems to be employed for organizing stem cell niches in adult continuously growing teeth. Furthermore, transitions between mature cell types elicited by trauma might represent a replay of embryonic continuous cell states. Alternatively, they could constitute transitions that evolved de novo, not known from the developmental paradigm. In this review, we discuss and exemplify how dental cell types exhibit plasticity during dynamic processes such as development, self-renewal, repair, and dental replacement. Hypothetically, minor plasticity of cell phenotypes and greater plasticity of transitions between cell subtypes might provide a better response to lifetime challenges, such as damage or dental loss. This plasticity might be additionally harnessed by the evolutionary process during the elaboration of dental cell subtypes in different animal lineages. In turn, the diversification of cell subtypes building teeth brings a diversity of their shape, structural properties, and functions.

Dental Anomalies in a Sample of Lebanese Children: a Retrospective Study

Background

Dental anomalies (DAs) represent a significant chapter in pediatric dentistry with a lot of practical relevance. Both primary and permanent dentitions may be affected.

Objective

The main objective of our study was to evaluate, using digital panoramic radiographs, the prevalence, distribution, and patterns of DAs in a sample of Lebanese children aged between 8 and 15 years old.

Methods

112 digital panoramic radiographs of patients aged between 8 and 15 years (60 males and 52 females) from the year 2017 till 2022 attending the department of Pediatric Dentistry and Dental Public Health at the Faculty of Dental Medicine at the Lebanese University were assessed for DAs of number (hypodontia, oligodontia, hyperdontia), of size (microdontia, macrodontia), of shape (fusion, gemination, dilaceration, taurodontism), of position (transposition, ectopia, impaction), and of structure (dentin dysplasia, amelogenesis imperfecta, dentinogenesis imperfecta). The data were analyzed statistically using Chi-square and Fisher's exact tests.

Results

Out of 112 patient radiographs, 84 showed at least one DA, which suggests a very high prevalence (75%). Among them, 36.9% exhibited multiple types of anomalies. These 84 patients showed a total of 274 DAs, distributed equally among males and females.

Conclusion

Dentists should be alerted to the presence of DAs. Their high prevalence requires careful clinical and radiological examinations for early detection. Regular monitoring is mandatory and could guide preventive approaches to minimize associated dental complications.

Integration of multimodal data in the developing tooth reveals candidate regulatory loci driving human odontogenic phenotypes

Human odontogenic aberrations such as abnormal tooth number and delayed tooth eruption can occur as a symptom of rare syndromes or, more commonly, as nonsyndromic phenotypes. These phenotypes can require extensive and expensive dental treatment, posing a significant burden. While many dental phenotypes are heritable, most nonsyndromic cases have not been linked to causal genes. We demonstrate the novel finding that common sequence variants associated with human odontogenic phenotypes are enriched in developmental craniofacial enhancers conserved between human and mouse. However, the bulk nature of these samples obscures if this finding is due to the tooth itself or the surrounding tissues. We therefore sought to identify enhancers specifically active in the tooth anlagen and quantify their contribution to the observed genetic enrichments. We systematically identified 22,001 conserved enhancers active in E13.5 mouse incisors using ChIP-seq and machine learning pipelines and demonstrated biologically relevant enrichments in putative target genes, transcription factor binding motifs, and in vivo activity. Multi-tissue comparisons of human and mouse enhancers revealed that these putative tooth enhancers had the strongest enrichment of odontogenic phenotype-associated variants, suggesting a role for dysregulation of tooth developmental enhancers in human dental phenotypes. The large number of these regions genome-wide necessitated prioritization of enhancer loci for future investigations. As enhancers modulate gene expression, we prioritized regions based on enhancers' putative target genes. We predicted these target genes and prioritized loci by integrating chromatin state, bulk gene expression and coexpression, GWAS variants, and cell type resolved gene expression to generate a prioritized list of putative odontogenic phenotype-driving loci active in the developing tooth. These genomic regions are of particular interest for downstream experiments determining the role of specific dental enhancer:gene pairs in odontogenesis.

Bioarchaeological Notes on the Commingled Human Remains Held in the Church of Saint Francis of Paola, Sant’Angelo di Brolo, Sicily, Italy

In this study, we examine human skeletal remains from the church of Saint Francis of Paola located in the small town of Sant’Angelo di Brolo, in the Italian region of Sicily. The preserved skeletal remains were temporarily transferred from their permanent resting place in the crypt for a macroscopic examination and evaluation. Various established methods were used to estimate age at death, sex, stature, any evidence of disease(s) as well as the fact that there was a minimum of 15 individuals. The findings were then subdivided into different groups of pathologies and recorded as individual cases. Amongst which, dental issues and cases of trauma were most prevalent. Additional conditions such as joint disease, congenital, metabolic and multifactorial disorders were also identified. The prevalence of dental decay indicates that the group’s diet consisted largely of carbohydrates, and that their oral hygiene was poor. Furthermore, evidence of trauma and poor healing suggested that the town was isolated from the main medical centres of the island. Severe complications of traumas linked with a loss of movement and overall independence, as well as physical pain, must have had a significant impact on the lives of those affected.

The Human Genetics of Dental Anomalies

The development of tooth is a highly complex procedure and mastered by specific genetic programs. Genetic alterations, environmental factors, and developmental timing can disturb the execution of these programs, and result in various dental anomalies like hypodontia/oligodontia, and supernumerary teeth, which are commonly seen in our clinical practice. Advances in molecular research enabled the identification of various genes involved in the pathogenesis of dental anomalies. In the near future, it will help provide a more accurate diagnosis and biological-based treatment for these anomalies. In this article, we present the molecular phenomenon of tooth development and the genetics of various dental anomalies.

Extraction of Supernumerary Nasal Tooth by Endoscopic Approach

The occurrence of the supernumerary tooth in the nasal cavity is uncommon. If not diagnosed and treated early, it may lead to various complications. Nasal endoscopy not only helps in proper diagnosis but also is an effective approach towards the extraction of the nasal tooth. It increases precision and reduces morbidity associated with the surgery.

Phenotypic heterogeneity of non-syndromic supernumerary teeth: genetic study

BACKGROUND

Numerical dental anomalies, through their phenotypic diversity and etiological complexity, represent a very topical chapter in dental practice. In Romania, there is no recent complex genetic study, regarding supernumerary teeth (ST), as a whole.

PATIENTS, MATERIALS AND METHODS

In this research, through the specific genetic study of the phenotypic variability of ST, completed with clinical examinations and paraclinical investigations, to which statistical determinations were added, we performed a complex genetic-clinical and statistical analysis of ST, within a representative group, consisting of 574 patients, who came for specialized dental treatment, between 01/01/2018-05/30/2019, at the private dental offices (Lucky Dental), in Bucharest, Romania.

RESULTS

Following this study, it was possible to characterize the phenotypic variability of ST, to analyze the pattern of abnormality genetic transmission in the families of investigated patients, to identify people at risk, and specify the therapeutic conduct of choice, specific to each case.

CONCLUSIONS

We consider this paper to be of interest for medical practice by bringing new, recent data on the current prevalence of non-syndromic ST, their clinical phenotypes, and the specifics of their genetic determinism in the studied population group.

Conservative surgical management of a supernumerary tooth in the nasal cavity

A 9-year-old girl presented with a foreign body obstruction inside her nose. The condition led to pain and nasal congestion. CT showed the presence of a radiopaque mass similar to a tooth in the right nasal cavity. Diagnosis of a supernumerary intranasal tooth was made and extraction was performed under general anaesthesia. An ectopic tooth in the nasal cavity is rare and surgical removal is recommended to eliminate the symptoms.

Management of Two Cases of Supernumerary Teeth

Supernumerary teeth are commonly observed as an isolated developmental anomaly. While the familial tendency of supernumerary teeth has been documented, its genetic causality has not yet been determined. The purpose of this paper was to presents two cases with supernumerary teeth and the process leading to the diagnosis and determination of their underlying conditions. Cases were evaluated and family histories reviewed. Genetic counseling was recommended for the probands and followed by genetic testing of selected family members. The proband of family one, who has multiple supernumerary teeth, was determined to have a RUNX2 missense mutation (c.379C>T, p. Pro127Ser) and diagnosed with cleidocranial dysplasia. The proband of family two, who has a premolar region supernumerary tooth, was reported to have no bone defects also presented with a RUNX2 missense mutation (c.1381G>C, p. Gly461Arg). When patients present with multiple supernumerary teeth, a recommendation and guidance to genetic counseling and testing may facilitate accurate diagnosis and management.

Non-syndromic cleft lip with or without palate-susceptible SNPs is associated with hyperdontia

BACKGROUND

Non-syndromic supernumerary teeth (NSST) or hyperdontia may share common genetic determinants with non-syndromic cleft lip with or without palate (NSCL/P). The aim of this study was to test the associations between five genome-wide-associated NSCL/P-susceptible single nucleotide polymorphisms (SNPs) (rs2235371, rs7078160, rs8049367, rs4791774, and rs13041247) and the occurrence of NSST.

MATERIALS AND METHODS

A total of 163 cases and 326 controls were recruited and their genomic DNA was extracted from blood samples. Five NSCL/P-susceptible SNPs (rs2235371, rs7078160, rs8049367, rs4791774, and rs13041247) were genotyped by TaqMan method. Odds ratio (OR) and 95% confidence interval (CI) were used to estimate the associations between the SNPs and the risk of NSST by PLINK software.

RESULTS

Rs4791774 (A > G) and rs13041247 (T > C) were associated with risk of NSST (rs4791774: P_add  = 0.011, OR, 95% CI = 0.62, 0.43-0.90; rs13041247: P_homo  = 0.031, OR, 95% CI = 1.79, 1.05-3.05) and one supernumerary tooth (rs4791774: P_dom  = 0.009, OR, 95% CI = 0.56, 0.36-0.87; rs13041247: P_homo  = 0.034, OR, 95% CI = 1.82, 1.05-3.15). Rs4791774 (A > G) was also showed association with risk of upper arch supernumerary teeth only (P_add  = 0.010, OR, 95% CI = 0.60, 0.41-0.89).

CONCLUSION

Non-syndromic cleft lip with or without palate-susceptible loci rs4791774 (A > G) and rs13041247 (T > C) were associated with the risk of supernumerary teeth.

Two Rare Cases of Non-Syndromic Paramolars with Family Occurrence and a Review of Literature

Supernumerary teeth (or hyperdontia) are teeth that exceed the normal number of deciduous or permanent teeth in the oral cavity. The occurrence of supernumerary teeth without any associated syndrome has been frequently reported and many case reports have been published. This article reports two rare cases of familial occurrence of multiple paramolars without the presence of any other syndrome for two consecutive generations. Limited cases of bilateral maxillary or mandibular paramolars have been reported. In addition, prevalence, classification, etiology, complications, diagnosis and therapeutic strategies that may be adopted when supernumeraries occur are discussed. A review of similar cases published in the literature is included as well.

Twin supernumerary teeth: A tale of two cases

Multiple supernumerary teeth are one of the most common developmental anomalies in humans. They could be associated with prolonged retention of deciduous teeth, displacement or rotation of the adjacent teeth, crowding, aberrations in the root morphology (dilacerations), and failure in eruption or impaction of the succedaneous teeth. This article highlights 2 cases of non-syndromic mandibular twin supernumerary teeth in young female clients with a chief complaint of spacing between the teeth and over-retained deciduous teeth. A diligent clinical and radiographic monitoring is warranted considering the early innocuous effects and delayed adverse effects of this condition.

Clinical and radiological findings in a severe case of cleidocranial dysplasia

Cleidocranial dysplasia (CCD) is a rare congenital autosomal dominant condition, causing hypoplasia of the clavicle, abnormal formation of teeth, skeletal and craniofacial bones. CCD is caused by the mutation of RUNX2/CBFA1 present in the short arm of chromosome 6 at position 21.1, a transcription factor essential for the formation of teeth, cartilage and bone. Patients with CCD show the classical features of excessive mobility of the shoulder bone, lack of resorption of the deciduous teeth, failure to erupt permanent teeth, multiple impacted and supernumerary teeth, and open fontanelle and sutures of the skull. In this article we report a case of CCD in a 16-year-old male patient, with an aim to highlight the clinical, radiological and recommended treatment guidelines.

Investigation of SOSTDC1 gene in non-syndromic patients with supernumerary teeth

Background

The etiology of supernumerary teeth is still unclear however heredity is believed to be a major factor and this idea was supported by several case reports. Recently, a relationship between supernumerary tooth formation and deficiency of Uterine Sensitization Associated Gene-1 (Usag-1), a rat gene that is expressed in sensitized endometrium, was reported in mice. The human homolog gene for Usag-1, Sclerostin Domain Containing 1 (SOSTDC1), shows 85% identity with mouse Usag-1. The present study aimed to investigate SOSTDC1 coding regions in non-syndromic patients with one or more supernumerary teeth.

Material and Methods

Twenty-five non-syndromic patients (21 male and 4 female) aged 5-15 years, with one or more supernumerary teeth were included in the study. Saliva samples were collected from patients and DNA samples were isolated and analyzed using PCR.

Results

Eight phenotypes of supernumerary tooth formation were observed in the study. From the DNA analysis, 2 novel and 3 previously identified sequence alterations were identified however, in investigating the Usag-1 homolog SOSTDC1 gene, the present study could not find any phenotype-genotype relationship.

Conclusions

There are many SOSTDC1 homolog genes in the human genome and future studies should investigate these candidate genes. Also studies in larger case groups including family members may reveal the hereditary pattern.

Key words:Genetics, Usag-1, mesiodens, DNA sequencing, pediatric dentistry, PCR.

The mineral content of the hard dental tissue of mesiodens

OBJECTIVE

Mesiodens is the most common form of supernumerary tooth mainly located between the maxillary central incisors. Its etiology is not completely understood but both genetic and environmental factors are assumed. The degree of mineralization and inorganic element content in hard tooth tissues is poorly understood as well as is the durability and suitability for allo- and auto-transplantation. Therefore aim of this study was to examine the content of inorganic elements.

MATERIALS AND METHODS

This study included 26 mesiodens teeth and 26 normal central incisor teeth as controls. All specimens were prepared for SEM/EDS analysis which was aimed at specific sites on the enamel, dentine and cementum in order to evaluate the weight percentage and ratio of important inorganic elements.

RESULTS

and Conclusion. The results showed that there was a difference in the weight percentage of selected inorganic elements (calcium, phosphorus, oxygen, carbon, magnesium and sodium) in all three types of dental hard tissues but the differences were mostly expressed in the cementum tissue. The statistical analysis showed that the differences were marginally significant especially for calcium and phosphorus values and ratio in the enamel and dentine. The carbon and magnesium content in all three hard tissues showed the most differences, but overall, the hard tissues mineral content of the mesiodens did not differs significantly from healthy teeth.

High incidence of cervical ribs indicates vulnerable condition in Late Pleistocene woolly rhinoceroses

Mammals as a rule have seven cervical vertebrae, a number that remains remarkably constant. Changes of this number are associated with major congenital abnormalities (pleiotropic effects) that are, at least in humans, strongly selected against. Recently, it was found that Late Pleistocene mammoths (Mammuthus primigenius) from the North Sea have an unusually high incidence of abnormal cervical vertebral numbers, approximately ten times higher than that of extant elephants. Abnormal numbers were due to the presence of large cervical ribs on the seventh vertebra, indicating a homeotic change from a cervical rib-less vertebra into a thoracic rib-bearing vertebra. The high incidence of cervical ribs indicates a vulnerable condition and is thought to be due to inbreeding and adverse conditions that may have impacted early pregnancies in declining populations. In this study we investigated the incidence of cervical ribs in another extinct Late Pleistocene megaherbivore from the North Sea and the Netherlands, the woolly rhinoceros (Coelodonta antiquitatis). We show that the incidence of abnormal cervical vertebral numbers in the woolly rhinoceros is unusually high for mammals (15,6%, n = 32) and much higher than in extant Rhinoceratidae (0%, n = 56). This indicates that woolly rhinoceros lived under vulnerable conditions, just like woolly mammoths. The vulnerable condition may well have contributed to their eventual extinction.

A novel mutation of adenomatous polyposis coli (APC) gene results in the formation of supernumerary teeth

Supernumerary teeth are teeth that are present in addition to normal teeth. Although several hypotheses and some molecular signalling pathways explain the formation of supernumerary teeth, but their exact disease pathogenesis is unknown. To study the molecular mechanisms of supernumerary tooth‐related syndrome (Gardner syndrome), a deeper understanding of the aetiology of supernumerary teeth and the associated syndrome is needed, with the goal of inhibiting disease inheritance via prenatal diagnosis. We recruited a Chinese family with Gardner syndrome. Haematoxylin and eosin staining of supernumerary teeth and colonic polyp lesion biopsies revealed that these patients exhibited significant pathological characteristics. APC gene mutations were detected by PCR and direct sequencing. We revealed the pathological pathway involved in human supernumerary tooth development and the mouse tooth germ development expression profile by RNA sequencing (RNA‐seq). Sequencing analysis revealed that an APC gene mutation in exon 15, namely 4292‐4293‐Del GA, caused Gardner syndrome in this family. This mutation not only initiated the various manifestations typical of Gardner syndrome but also resulted in odontoma and supernumerary teeth in this case. Furthermore, RNA‐seq analysis of human supernumerary teeth suggests that the APC gene is the key gene involved in the development of supernumerary teeth in humans. The mouse tooth germ development expression profile shows that the APC gene plays an important role in tooth germ development. We identified a new mutation in the APC gene that results in supernumerary teeth in association with Gardner syndrome. This information may shed light on the molecular pathogenesis of supernumerary teeth. Gene‐based diagnosis and gene therapy for supernumerary teeth may become available in the future, and our study provides a high‐resolution reference for treating other syndromes associated with supernumerary teeth.

Dental anomalies: prevalence and associations between them in a large sample of non-orthodontic subjects, a cross-sectional study

Background

To analyze the prevalence and associations between dental anomalies detectable on panoramic radiographs in a sample of non-orthodontic growing subjects.

Methods

For this cross-sectional study, digital panoramic radiographs of 5005 subjects were initially screened from a single radiographic center in Rome. Inclusion criteria were: subjects who were aged 8–12 years, Caucasian, and had good diagnostic quality radiographs. Syndromic subjects, those with craniofacial malformation, or orthodontic patients were excluded and this led to a sample of 4706 subjects [mean (SD) age = 9.6 (1.2) years, 2366 males and 2340 females]. Sample was subsequently divided into four subgroups (8, 9, 10, and 11–12 year-old groups). Two operators examined panoramic radiographs to observe the presence of common dental anomalies. The prevalence and associations between dental anomalies were also investigated.

Results

The overall prevalence of dental anomalies was 20.9%. Approximately, 17.9% showed only one anomaly, 2.7% two anomalies, while only 0.3% had more than two anomalies. The most frequent anomalies were the displacement of maxillary canine (7.5%), hypodontia (7.1%), impacted teeth (3.9%), tooth ankylosis (2.8%), and tooth transposition (1.4%). The lower right second premolar was the most frequent missing teeth; 3.7% had only one tooth agenesis, and 0.08% had six or more missing tooth (Oligodontia). Mesiodens was the most common type of supernumerary tooth (0.66%). Two subjects had taurodontic tooth (0.04%). Tooth transpositions and displacement of maxillary canine were seen in 1.4 and 7.5%, retrospectively (approximately 69 and 58% were in the 8 and 9 year-old groups, retrospectively). Significant associations were detected between the different dental anomalies (P < .05).

Conclusions

The results of our study revealed significant associations among different dental anomalies and provide further evidences to support common etiological factors.

Electronic supplementary material

The online version of this article (doi:10.1186/s12903-017-0352-y) contains supplementary material, which is available to authorized users.

Genetic Disorders of Dental Development: Tales from the Bony Crypt

PURPOSE OF REVIEW

The ebb and flow of genetic influence relative to the understanding of craniofacial and dental disorders has evolved into a tacit acceptance of the current genetic paradigm. This review explores the science behind craniofacial and dental disorders through the lens of recent past and current findings and using tooth agenesis as a model of advances in craniofacial genetics.

RECENT FINDINGS

Contemporary studies of craniofacial biology takes advantage of the technological resources stemming from the genomic and post-genomic eras. Emerging data highlights the role of key genes and the epigenetic landscape controlling these genes, in causing dentofacial abnormalities. We also report here a novel Glu78FS MSX1 mutation in one family segregating an autosomal dominant form of severe tooth agenesis as an illustration of an evolving theme, i.e., different mutations in the same gene can result in a spectrum of dentofacial phenotypic severity. The future of clinical therapeutics will benefit from advances in genetics and molecular biology that refine the genotype-phenotype correlation. Indeed, the past century suggests a continued convergence of genetic science in the practice of clinical dentistry.

A novel NHS mutation causes Nance-Horan Syndrome in a Chinese family

Background

Nance-Horan Syndrome (NHS) (OMIM: 302350) is a rare X-linked developmental disorder characterized by bilateral congenital cataracts, with occasional dental anomalies, characteristic dysmorphic features, brachymetacarpia and mental retardation. Carrier females exhibit similar manifestations that are less severe than in affected males.

Methods

Here, we report a four-generation Chinese family with multiple affected individuals presenting Nance-Horan Syndrome. Whole-exome sequencing combined with RT-PCR and Sanger sequencing was used to search for a genetic cause underlying the disease phenotype.

Results

Whole-exome sequencing identified in all affected individuals of the family a novel donor splicing site mutation (NM_198270: c.1045 + 2T > A) in intron 4 of the gene NHS, which maps to chromosome Xp22.13. The identified mutation results in an RNA processing defect causing a 416-nucleotide addition to exon 4 of the mRNA transcript, likely producing a truncated NHS protein.

Conclusions

The donor splicing site mutation NM_198270: c.1045 + 2T > A of the NHS gene is the causative mutation in this Nance-Horan Syndrome family. This research broadens the spectrum of NHS gene mutations, contributing to our understanding of the molecular genetics of NHS.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-016-0360-9) contains supplementary material, which is available to authorized users.

Clear double layer Bioplast feeding plate for neonates with cleft palate

An infant with cleft palate was referred to cleft clinic of the Orthodontic Department. The mother was concerned to feed the child because of the escape of milk from the nose. Intraoral examination revealed a large palatal cleft extending from hard to soft palate involving uvula. The impression was taken and dental cast obtained. A 3 mm soft and afterward a 1 mm hard Bioplast plate was pressed using Biostar device (Scheu-Dental Gmbh, Iserlohn, Germany) on the model. Finally, a hole was prepared on the anterior part to put a thread through it. The infant tolerated the plate immediately and encounters no difficulties during feeding. The inlaying soft Bioplast plates eliminate the risk of tissue irritation, whereas the covering hard Bioplast plate supplies endurance. The fabrication of the clear Bioplast feeding plate is easy and less time-consuming compared with acrylic plates and may be recommended in crowded and overloaded cleft centers.

Prevalence and management of natal/neonatal teeth in cleft lip and palate patients

Objective:

The aim of this study was to determine the prevalence and distribution of natal/neonatal teeth in infants with cleft lip and palate (CLP) according to gender, involving jaw and side and to show the management of some cases.

Materials and Methods:

A retrospective study was carried out on medical history and photographic records of 69 infants with CLP, who were treated at the CLP clinic of Yeditepe University between years 2014–2015. The presence of neonatal teeth was determined, and if present the gender, type of cleft, and position were recorded. Statistical analysis was performed.

Results:

Neonatal teeth were observed in 7% of the study group. No significant differences were found between cleft types and gender (P > 0.05). The prevalence of neonatal teeth in bilateral, unilateral and isolated cleft type was 16.5%, 6.5%, and none, respectively. All neonatal teeth were located in the maxilla and on the cleft-side (100%).

Conclusion:

The presence of natal/neonatal teeth in infants with CLP was not rare. In all of these cases the teeth were located adjacent to the cleft region. In isolated palatal cleft, where the alveolar region including the teeth buds are away from the cleft, no neonatal teeth were observed. It may be concluded that neonatal teeth in infants with CLP are frequently present and located inside the borders of the presurgical orthopedic treatment (POT) plate. Therefore, if possible, immediate extraction of the neonatal teeth is advised or if not possible because of systemic health reasons, modifications of the plate are required.

Developmental Disorders Affecting Jaws

Teeth are housed in mandible and maxilla and are known to undergo variations in clinical presentation depending on the degree of abnormality during growth and development. It is essential to identify these variations in normal anatomy so that appropriate treatment can be initiated to address the anomaly. Some normal anatomic variations are harmless and best left alone, whereas others require intervention. Radiology plays a vital role in identification of such anomalies. This article focuses on the diagnostic radiographic interpretation and strategies to include pertinent differential diagnosis. Also discussed is the importance of advanced imaging and its appropriateness in the diagnosis and interpretation.

Multiple Geminated Supernumerary Premolars: A Rare Case Report

Supernumerary teeth may be defined as any teeth or tooth substance in excess of the usual configuration of 20 deciduous and 32 permanent teeth. Gemination is defined as an attempt by a single tooth bud to divide, with a resultant formation of either a large tooth with a bifid crown or two completely divided teeth throughout the crown and root. Geminated supernumerary premolar is a rarity and the possibility of multiple occurrences is even rarer. An exhaustive review of English literature and a PubMed search conducted using the terms “gemination” and “multiple geminated supernumerary” revealed no case of multiple geminated supernumerary premolars. We report a case of multiple geminated supernumerary premolars in a 23-year-old male.