Decoding the multifaceted signatures and transcriptomic characteristics of stem cells derived from apical papilla and dental pulp of human supernumerary teeth.

Supernumerary teeth are advantaged sources for high-quality stem cell preparation from both apical papilla (SCAP-Ss) and dental pulp (DPSCs). However, the deficiency of the systematic and detailed comparison of the biological and transcriptomic characteristics of the aforementioned stem cells largely hinders their application in regenerative medicine. Herein, we collected supernumerary teeth for SCAP-S and DPSC isolation and identification by utilizing multiple biological tests (e.g., growth curve, cell cycle and apoptosis, adipogenic and osteogenic differentiation, and quantitative real-time polymerase chain reaction). Furthermore, we took advantage of transcriptome sequencing and multifaceted bioinformatic analyses to dissect the similarities and diversities between them. In this study, we found that SCAP-Ss and DPSCs showed indistinctive signatures in morphology and immunophenotypes, whereas with diversity in cell vitality and multi-lineage differentiation as well as gene expression profiling and differentially expressed genes-associated gene ontology and signaling pathways. Collectively, our data indicated the diversity of the multifaceted signatures of human supernumerary teeth-derived stem cells both at the cellular and molecular levels, which also supplied new references for SCAP-Ss serving as splendid alternative stem cell sources for regenerative medicine purposes.

Rare Genetic Variants in Human APC Are Implicated in Mesiodens and Isolated Supernumerary Teeth.

The activation of Wnt/ß-catenin signalling is a prerequisite for odontogenesis. APC, a member of the AXIN-CK1-GSK3ß-APC ß-catenin destruction complex, functions to modulate Wnt/ß-catenin signalling to establish regular teeth number and positions. APC loss-of-function mutations are associated with the over-activation of WNT/ß-catenin signalling and subsequent familial adenomatous polyposis (FAP; MIM 175100) with or without multiple supernumerary teeth. The ablation of Apc function in mice also results in the constitutive activation of ß-catenin in embryonic mouse epithelium and causes supernumerary tooth formation. The objective of this study was to investigate if genetic variants in the APC gene were associated with supernumerary tooth phenotypes. We clinically, radiographically, and molecularly investigated 120 Thai patients with mesiodentes or isolated supernumerary teeth. Whole exome and Sanger sequencing identified three extremely rare heterozygous variants (c.3374T>C, p.Val1125Ala; c.6127A>G, p.Ile2043Val; and c.8383G>A, p.Ala2795Thr) in APC in four patients with mesiodentes or a supernumerary premolar. An additional patient with mesiodens was compound as heterozygous for two APC variants (c.2740T>G, p.Cys914Gly, and c.5722A>T, p.Asn1908Tyr). Rare variants in APC in our patients are likely to contribute to isolated supernumerary dental phenotypes including isolated mesiodens and an isolated supernumerary tooth.

Type II Pfieffer misdiagnosed as Crouzon syndrome with additional features of supernumerary teeth and localized symmetrical gigantism: a case report.

BACKGROUND: Pfieffer syndrome is among the syndromes seen in the recognized variant of the FGFR2 gene. There are several conditions related to this variant and a very closely related condition is Crouzon syndrome. This case is important to report because the neonate was a delayed referral from another region, without clear counseling and information on the gravity of situation. We describe additional features , not previously described in Pfieffer or Crouzon syndrome, supernumerary teeth and localized symmetrical gigantism of thumbs and great toes on both sides. That a genetic testing is essential to further manage and counsel to avoid lost opportunities for future births. Several cases are seen in this unit annually, and there is need for a more consolidated and comprehensive counseling and genetic testing. Once early diagnosis is done and the case is recognized to be untreatable, it was avert the need to refer. CASE PRESENTATION: A 2-week-old male African neonate referred from outside the region, presented with massive proptosis soon after delivery, with signs of pan-ophthalmitis and neonatal sepsis. The infant had additional multiple malformations and features initially diagnosed as Crouzon syndrome , but later confirmed after genetic testing to be Type II Pfieffer syndrome. A through clinical evaluation and genetic testing would prevent undue referral to a tertiary center, or if needed, the baby should have been referred much earlier. The uniqueness of this case is the presence of supernumerary teeth. CONCLUSION: A complicated, difficult to remedy case, referred to tertiary center, investigated, and sent back home with no significant intervention. Genetic test confirmed the typical findings of Pfieffer Type II. Presented for describing additional unique features of supernumerary teeth and localized gigantism and ethical challenges in management.

Identification of a novel missense mutation in non-syndromic familial multiple supernumerary teeth.

OBJECTIVE: This study intended to evaluate the involvement of genetic factors in the etiology of non-syndromic multiple supernumerary teeth. DESIGN: We filtered the single nucleotide polymorphisms (SNPs) of the proband and his mother with similar phenotypes through whole-genome sequencing (WGS). By integrating multiple databases related to human genome mutations and disease information for mutation annotation, we excluded the SNPs of people without supernumerary teeth. Subsequently, the bioinformatics analysis tools (Sorting Intolerant From Tolerant (SIFT) < 0.05, Polymorphism Phenotyping (PolyPhen) > 0.90) were used to screen out the most correlated SNPs of the disease, besides, Gene Ontology (GO) analysis (P<0.05, FDR<0.05) and Sanger sequencing was applied to further verify the candidate pathogenic mutation point. RESULTS: A novel heterozygous variant in fer-1 like family member 6 (FER1L6) gene likely denoted pathogenicity in non-syndromic familial multiple supernumerary teeth. We identified a cohort of 3499 non-synonymous SNPs (nsSNPs), and only 142 nsSNPs with the score of SIFT < 0.05 and PolyPhen > 0.90 were retained. Then we got 54 nsSNPs from 31 candidate genes through GO analysis. Sanger sequencing revealed a missense variant in exon 31 of the FER1L6 gene, causing a transition from guanine to adenine in position 1447 of protein kinase C conserved region 2. CONCLUSIONS: We identified a novel heterozygous chromosome 8q24.13 mutation of FER1L6, which was a new mutation site identified in non-syndromic familial multiple supernumerary teeth through genetic analysis of a Chinese family.

RUNX2 Nonsense Mutation Associated with Cleidocranial Dysplasia with Unusual Dental Features.

Purpose: The purpose of this case report is to describe a RUNX2 nonsense mutation associated with cleidocranial dysplasia (CCD) with unusual dental features. The patient was a 12-year-old Brazilian girl who sought dental care due to over-retention of primary teeth and absence of erupted permanent teeth. Clinical and radiographic examinations revealed multiple impacted permanent teeth, a prominent cingulum of the permanent impacted maxillary incisors and enamel defects (hypoplasia and hypomineralization) in addition to skeletal abnormalities. No supernumerary teeth were present. The diagnostic hypothesis of CCD was raised and the patient was refer- red to the genetic medical service, where the diagnosis was cofirmed. After RUNX2 genetic screening, including polymerase chain reaction and sequencing of both DNA strands, a heterozygous nonsense mutation was identified in exon 2 (c.193 C>T [Q65X]). This article reports unusual dental features in a patient with CCD.

Assessment of risk factors and molecular biomarkers in children with supernumerary teeth: a single-center study.

BACKGROUND: Supernumerary teeth are considered one of the commonly observed dental anomalies in children. Several theories have been proposed to explain the presence of supernumerary teeth, including environmental and genetic factors. This study aimed to identify the different risk factors and molecular biomarkers in patients presented with supernumerary teeth. METHODS: This case-control study included 240 children, 6 to 12-year-old. They were divided into a test group (n = 120 children presented with supernumerary teeth) and a control group (n = 120 children with no supernumerary teeth). Questionnaires were distributed to assess demographics and exposure to several environmental factors. Ten extracted supernumerary teeth from the test group were processed for histopathological analysis. RESULTS: Male gender, dental history of severe oral infection or medical history of chemotherapy treatment, previous history of taking medication or illness during pregnancy, family history of neoplastic disorders, use of electronic devices, and living beside agricultural fields or industrial areas were found to be statistically significant associated with the risk of supernumerary teeth development. Immunohistochemistry panel revealed that supernumerary teeth showed enhanced expression of wingless (Wnt) and sonic hedgehog (SHH) proteins as well as a reduced expression of adenomatous polyposis coli (APC) protein, denoting molecular derangement in a group of pathways classically believed to be involved in its pathogenesis. CONCLUSIONS: Males were more frequently affected by supernumerary teeth than females. Several risk factors were notably correlated with the existence of supernumerary teeth. Additionally, molecular biomarkers assessment demonstrated a high expression level of pro-tumorigenic proteins such as Wnt and SHH in patients with supernumerary teeth.

Sequencing analysis of exons 5 and 6 in RUNX2 in non-syndromic patients with supernumerary tooth in Kelantan, Malaysia.

OBJECTIVE: The aim of this study is to do a sequencing analysis of RUNX2 in non-syndromic patients with supernumerary tooth. MATERIALS AND METHODS: Fifty-three patients with supernumerary tooth were identified retrospectively from 1,275 radiographic reviews who attended the Hospital Universiti Sains Malaysia (USM) Dental Clinic. Informed consent was obtained from the patients prior to the study. Blood samples were collected from 41 patients and DNA extractions were performed out of which 10 samples were chosen randomly for PCR amplification using designated primers for RUNX2 followed by DNA sequencing analysis. RESULTS: This study involved 28 male patients (68.3%) and 13 female patients (31.7%) with a gender ratio of 2.2:1 and mean age of 15.9 ± 6.2 years. DNA extraction yielded ~ 40 ng/µl of concentrated DNA, and each DNA sample had more than 1500 bp of DNA length. The purity ranged between 1.8 and 2.0. DNA sequencing analysis did not reveal any mutations in exons 5 and 6 of RUNX2. CONCLUSION: This study did not reveal any mutations in exons 5 and 6 of RUNX2 in non-syndromic patients with supernumerary tooth. CLINICAL RELEVANCE: Analysis of mutations in RUNX2 is important to enhance the understanding of tooth development in humans.

Gas1 Regulates Patterning of the Murine and Human Dentitions through Sonic Hedgehog.

The mammalian dentition is a serially homogeneous structure that exhibits wide numerical and morphological variation among multiple different species. Patterning of the dentition is achieved through complex reiterative molecular signaling interactions that occur throughout the process of odontogenesis. The secreted signaling molecule Sonic hedgehog (Shh) plays a key role in this process, and the Shh coreceptor growth arrest-specific 1 (Gas1) is expressed in odontogenic mesenchyme and epithelium during multiple stages of tooth development. We show that mice engineered with Gas1 loss-of-function mutation have variation in number, morphology, and size of teeth within their molar dentition. Specifically, supernumerary teeth with variable morphology are present mesial to the first molar with high penetrance, while molar teeth are characterized by the presence of both additional and absent cusps, combined with reduced dimensions and exacerbated by the presence of a supernumerary tooth. We demonstrate that the supernumerary tooth in Gas1 mutant mice arises through proliferation and survival of vestigial tooth germs and that Gas1 function in cranial neural crest cells is essential for the regulation of tooth number, acting to restrict Wnt and downstream FGF signaling in odontogenic epithelium through facilitation of Shh signal transduction. Moreover, regulation of tooth number is independent of the additional Hedgehog coreceptors Cdon and Boc, which are also expressed in multiple regions of the developing tooth germ. Interestingly, further reduction of Hedgehog pathway activity in Shhtm6Amc hypomorphic mice leads to fusion of the molar field and reduced prevalence of supernumerary teeth in a Gas1 mutant background. Finally, we demonstrate defective coronal morphology and reduced coronal dimensions in the molar dentition of human subjects identified with pathogenic mutations in GAS1 and SHH/GAS1, suggesting that regulation of Hedgehog signaling through GAS1 is also essential for normal patterning of the human dentition.

Genetic Pattern, Orthodontic and Surgical Management of Multiple Supplementary Impacted Teeth in a Rare, Cleidocranial Dysplasia Patient: A Case Report.

Background: Cleidocranial dysplasia (CCD) is a rare, autosomal dominant skeletal dysplasia with a prevalence of one per million births. The main causes of CCD are mutations in the core-binding factor alpha-1 (CBFA1) or runt-related transcription factor-2 (RUNX2), located at the 6p21 chromosomal region. RUNX2 plays important roles in osteoblast differentiation, chondrocyte proliferation and differentiation, and tooth formation. The disease is characterized by clavicular aplasia or hypoplasia, Wormian bones, delayed closure of cranial suture, brachycephalic head, maxillary deficiency, retention of primary teeth, inclusion of permanent teeth, and multiple supernumerary teeth. Materials and Methods: A 22-year-old girl suffering from cleidocranial dysplasia with short stature, narrow shoulders, craniofacial manifestations (short face, broad forehead, etc.) and dental anomalies (different lower dental elements under eruption, supernumerary and impacted multiple teeth, etc.) was examined at our service (Complex Operative Unit of Odontostomatology of Policlinico of Bari). RX Orthopantomography (OPG) and cone beam computed tomography (CBCT) were requested to better assess the position of the supernumerary teeth and their relationships with others and to evaluate the bone tissue. Results: Under eruption was probably caused by dental interferences with supernumerary teeth; hence, extractions of supernumerary upper canines and lower premolars were performed under general anaesthesia. Surgery outcome was excellent with good tissue healing and improvements in the therapeutic possibilities with future orthodontics. Conclusions: The objective of this article is to give an update about radiological, clinical, and molecular features of CCD and to alert the health team about the importance of establishing an early diagnosis and an appropriate treatment in these patients to prevent impacted teeth complications and to offer them a better quality of life.

Phenotypic dento-osseous characterization of a Brazilian family with Familial Adenomatous Polyposis.

OBJECTIVE: To perform a phenotypic characterization of the dento-osseous anomalies in a Brazilian family with Familial Adenomatous Polyposis (FAP) and to investigate the adenomatous polyposis coli (APC) causative variant. DESIGN: The study included a family of 14 individuals (Group A: affected; Group B: non-affected). The frequency of radiographic findings in both groups was evaluated according to the Dental Panoramic Radiograph Score (DPRS) diagnostic method. The accuracy and reproducibility of DPRS were tested. The DNA was isolated from the index patient's saliva and submitted to whole-exome and Sanger sequencing approach. RESULTS: DPRS ≥ 7 was observed in 80 % of Group A but in none of Group B. The most common findings in Group A were dense bone islands (60 %), hazy sclerosis (40 %), osteomas (40 %), and supernumerary tooth (20 %). DPRS has proved to be a reliable method while DPRS ≥ 5 and DPRS ≥ 7 were taken as positive for FAP, and reproducible diagnosis test considering that the evaluators correctly identified the affected patients (Kappa agreement>0.8, p = 0.002). A nonsense heterozygous mutation in the APC gene (c.1370C > G; p.Ser457*) of the index case was detected. CONCLUSION: FAP patients have a higher frequency of dento-osseous anomalies (p = 0.005). Bone abnormalities were more prevalent than dental anomalies (p = 0.001). Thus, FAP patients should be referred for dental examination and genetic counseling to perform early diagnosis of dento-osseous anomalies and evaluate the implications of the molecular findings in each particular family.

Isolated and Sporadic Human Mesiodens Is Associated with a Synonymous Variant in the ACVR2A Gene.

Purpose: The purpose of this study was to use targeted next-generation sequencing (NGS) to identify possible causative genes for isolated and sporadic human mesiodens. Methods: The targeted panel consisted of 101 target genes related to tooth development. NGS of this panel was initially performed on a discovery set (39 cases and 27 controls); association tests were performed after genotyping of nine selected variants in a validation set (57 cases and 56 controls). Results: Among these nine variants, a synonymous variant, ACVR2A (rs1128919) associated with mesiodens was identified. Moreover, in silico analysis was performed and demonstrated the instability of mRNA with the G allele. Conclusions: The formation of isolated and sporadic human mesiodens is associated with a synonymous variation in ACVR2A (rs1128919).

Non-syndromal multiple supernumerary and permanent impacted teeth in mother and her one child.

Multiple permanent impacted supernumerary teeth are rare and are most of the times associated with syndromes. The prevalence for non-syndromic multiple supernumerary teeth is less than 1%. We herein presenting a case of non-syndromic multiple supernumerary impacted teeth in a female patient and her child. The patient has three children; out of them, two had normal dentition and the youngest child had 60 teeth (35 impacted supernumerary with 25 erupted teeth). The patient herself had a total of 54 teeth. Their medical history was not significant. The systemic investigations were not suggestive of any syndrome and disease. Very few cases reported more than 30 supernumerary and impacted teeth bilaterally in both the jaws. This case report becomes unique as both mother and her child presented with more than 30 supernumerary impacted teeth.

FAM20B-catalyzed glycosaminoglycans control murine tooth number by restricting FGFR2b signaling.

BACKGROUND: The formation of supernumerary teeth is an excellent model for studying the molecular mechanisms that control stem/progenitor cell homeostasis needed to generate a renewable source of replacement cells and tissues. Although multiple growth factors and transcriptional factors have been associated with supernumerary tooth formation, the regulatory inputs of extracellular matrix in this regenerative process remains poorly understood. RESULTS: In this study, we present evidence that disrupting glycosaminoglycans (GAGs) in the dental epithelium of mice by inactivating FAM20B, a xylose kinase essential for GAG assembly, leads to supernumerary tooth formation in a pattern reminiscent of replacement teeth. The dental epithelial GAGs confine murine tooth number by restricting the homeostasis of Sox2(+) dental epithelial stem/progenitor cells in a non-autonomous manner. FAM20B-catalyzed GAGs regulate the cell fate of dental lamina by restricting FGFR2b signaling at the initial stage of tooth development to maintain a subtle balance between the renewal and differentiation of Sox2(+) cells. At the later cap stage, WNT signaling functions as a relay cue to facilitate the supernumerary tooth formation. CONCLUSIONS: The novel mechanism we have characterized through which GAGs control the tooth number in mice may also be more broadly relevant for potentiating signaling interactions in other tissues during development and tissue homeostasis.

Associations of the microRNA gene polymorphisms with the risk of non-syndromic supernumerary teeth in a Chinese population.

OBJECTIVE: Non-syndromic supernumerary teeth (NSST) are a common type of dental anomaly. microRNAs (miRNAs) play an important role in craniofacial and tooth development. Therefore, we hypothesized that single nucleotide polymorphisms (SNPs) of miRNAs may be associated with the susceptibility of NSST. MATERIALS AND METHODS: Four miRNA SNPs (rs2910164, rs11614913, rs2043556, and rs2682818) were selected, and their associations with NSST susceptibility were evaluated in a case-control study (163 NSST patients and 326 healthy controls). RESULTS: rs2910164 was significantly associated with a risk of lower NSST (additive model: OR = 4.00, 95 % CI = 1.76-9.09, P = 0.001), and rs2682818 showed nominal association with a risk of upper NSST (additive model: OR = 1.40, 95 % CI = 1.02-1.91, P = 0.037) and NSST among male patients (additive model: OR = 1.62, 95 % CI = 1.08-2.43, P = 0.020). CONCLUSION: Genetic variants of miR-146a/rs2910164 and miR-618/rs2682818 were likely associated with the risk of NSST in the Chinese population.

Impaired dentin mineralization, supernumerary teeth, hypoplastic mandibular condyles with long condylar necks, and a TRPS1 mutation.

Tricho-rhino-phalangeal syndrome type I, an autosomal dominant condition, is caused by heterozygous pathogenic variants in a zinc finger transcription factor, TRPS1, which has important roles in development of endochondral bones, teeth, and hair. Clinical manifestations of the patients include short stature, sparse, fine and slow-growing scalp hair, bulbous nose, supernumerary teeth, hip dysplasia, brachydactyly, and cone-shaped epiphyses of the phalangeal bones. OBJECTIVE: To clinically, radiographically, and molecular genetically investigate a patient with tricho-rhino-phalangeal syndrome type I. MATERIALS AND METHODS: Clinical and radiographic examination and mutation analysis of TRPS1 were performed. RESULTS: Clinical and radiographic examination indicated the patient had tricho-rhino-phalangeal syndrome type I. Sequencing of the TRPS1 gene revealed a heterozygous pathogenic variant (c.2762G>A; p.Arg921Gln). Oral examination showed supernumerary teeth, large dental pulp spaces, dental pulp stones, microdontia of the maxillary permanent lateral incisors, absence of the mandibular left second premolar and short root of the maxillary right second premolar, and hypoplastic mandibular condyles with long condylar necks. CONCLUSION: TRPS1 has an important function in regulating bone and dentin mineralization. Having large dental pulp spaces suggests that impaired dentin mineralization was the result of the TRPS1 pathogenic variant. This is the first patient with a TRPS1 pathogenic variant who had impaired dentin mineralization. This is also the third report showing the association between TRPS1 pathogenic variants and the presence of supernumerary teeth.

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.

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: Padd  = 0.011, OR, 95% CI = 0.62, 0.43-0.90; rs13041247: Phomo  = 0.031, OR, 95% CI = 1.79, 1.05-3.05) and one supernumerary tooth (rs4791774: Pdom  = 0.009, OR, 95% CI = 0.56, 0.36-0.87; rs13041247: Phomo  = 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 (Padd  = 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.

Lack of association between PAX6/SOSTDC1/FAM20B gene polymorphisms and mesiodens.

BACKGROUND: The purpose of this study was to analyze the association between the genetic polymorphism of genes (PAX6, SOSTDC1and FAM20B) and the susceptibility to mesiodens. METHODS: This study was carried out on 50 patients with mesiodens and 50 controls. The family history of each patient with mesiodens were recorded. Genomic DNA was extracted from saliva samples, and single nucleotide polymorphisms were detected in all exons and exon/intron boundaries of PAX6, SOSTDC1 and FAM20B using Sanger sequencing. The data were analyzed using pearson chi-square test with theoretical frequency ≥ 5. For theoretical frequency less than 5 but at least 1 (≤20% cell), the data were analyzed by continuity correction. For the rest, Fisher's Exact test was used. A P-value< 0.05 was considered statistically significant. The Odds ratio (OR) and confidence intervals (CI) were recorded. RESULTS: Three polymorphisms were detected in PAX6. Two polymorphisms were detected in SOSTDC1. Twenty-nine polymorphisms were detected in FAM20B. Although, the T allele of FAM20B (rs3766626) appears to be associated with mesiodens (P = 0.051), there were no significant differences of PAX6/SOSTDC1/FAM20B gene polymorphisms between the two groups. The T allele of FAM20B (rs3766626) was associated with susceptibility to two mesiodens (P < 0.001; OR = 8.333; CI = 2.516-27.600). CONCLUSIONS: Lack of association between PAX6/SOSTDC1/FAM20B gene polymorphisms and mesiodens in the population studied was detected. Further studies with large samples on T allele of FAM20B (rs3766626) are needed.

Main genetic entities associated with supernumerary teeth. / Principales entidades genéticas asociadas con dientes supernumerarios.

Supernumerary teeth represent a common human dental anomaly, defined as presence of extra teeth-more than the normal number foreseen in primary or permanent dentition. The prevalence has been reported between 0.2 to 3%, and is more frequent in males than females. The etiology is heterogeneous, highly variable and most of the cases are idiopathic. However, the presence of multiple impacted or erupted supernumerary teeth is rare and associated with some genetic syndromes: cleidocranial displasia, familial adenomatous polyposis, trichorhinophalangeal syndrome type I, Rubinstein-Taybi syndrome, Nance-Horan syndrome, Opitz G/BBB syndrome, oculofaciocardiodental syndrome and Robinow syndrome (autosomal dominant). The supernumerary teeth should be considered in order to possibly diagnose these entities with the aim of offering an interdisciplinary management and treatment, as well as offer adequate family genetic counseling.

Los dientes supernumerarios representan una anomalía dental frecuente en los seres humanos. Esta afección se define como la presencia de una mayor cantidad de dientes que los previstos en cuanto a los dientes de leche o a los permanentes. Según se ha notificado, la prevalencia varía entre el 0,2 % y el 3 % y es más frecuente en los varones que en las mujeres. Su etiología es heterogénea, sumamente variable y, en la mayoría de los casos, idiopática. Sin embargo, la presencia de múltiples dientes supernumerarios retenidos o erupcionados es infrecuente y está asociada con ciertos síndromes genéticos, como displasia cleidocraneal, poliposis adenomatosa familiar, síndrome tricorrinofalángico de tipo I, síndrome de Rubinstein-Taybi, síndrome de Nance-Horan, síndrome de Opitz G/BBB, síndrome oculofaciocardiodental y síndrome de Robinow (autosómico dominante). Se deben considerar los dientes supernumerarios para diagnosticar estas entidades a fin de ofrecer un abordaje interdisciplinario, además de brindar asesoramiento genético familiar adecuado.

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 (SOS-TDC1), 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