The epidemiology of supernumerary teeth and the associated molecular mechanism

Follistatin controls the number of murine teeth by limiting TGF-β signaling

Supernumerary teeth are common developmental anomalies of dentition. However, the factors and mechanisms driving their formation remain largely unknown. Here, we report that conditional knockout of Fst, encoding an antagonist for the transforming growth factor β (TGF-β) signaling pathway, in both oral epithelium and mesenchyme of mice (Fst CKO ) led to supernumerary upper incisor teeth, arising from the lingual dental epithelium of the native teeth and preceded by an enlarged and split lingual cervical loop. Fst-deficiency greatly activated TGF-β signaling in developing maxillary incisor teeth, associated with increased epithelium cell proliferation. Moreover, Fst CKO teeth exhibited increased expression of Tbx1, Sp6, and Sox2, which were identified as direct targets of TGF-β/SMAD2 signaling. Finally, we show that upregulation of Tbx1 in response to Fst-deficiency was largely responsible for the formation of extra teeth in Fst CKO mice. Taken together, our investigation indicates a novel role for Fst in controlling murine tooth number by restricting TGF-β signaling.

Minimally invasive intraoral removal of mesiodens via a transnasal, non-endoscopic approach: a systematic review on the purpose of 10 cases

Mesiodens, which emerge towards the nasal cavity, often require consultation in maxillofacial practice. Typically accessed through wide palatal flaps with ostectomy, this method involves limited visibility and poses the risk of damaging the roots and apex of adjacent dental structures. This study advocates a minimally invasive technique that involves vestibulotomy between the central incisors, facilitating direct and rapid access through nasal floor dissection, minimizing comorbidities. A systematic review was performed, following the PRISMA guidelines, apropos on ten clinical cases reported in this study. The MEDLINE/Pubmed and Web of Science databases were searched. Several variables were considered and are presented comprehensively in tables and figures. Additionally, 10 case reports with mesiodens in the maxilla were submitted to surgical treatment using a minimally invasive intraoral transnasal disinclusion. The initial literature search resulted in 37 articles, of which 9 met the inclusion criteria for the analysis. Regarding postoperative complications, no bone exposure, incisor root damage, extensive surgical approach, palatal or vestibular hematoma, or palatal necrosis was observed. However, 10% experienced superficial damage to the nasopalatine neurovascular, while 80% and 20% presented mild and moderate postoperative facial edema, respectively. Hypoesthesia in 20% of patients recovered in the first week, 40% in the first month and 40% at 3 months. The minimally invasive intraoral, transnasal, non-endoscopic approach emerges as a safe and predictable alternative to conventional surgical techniques. Presumes minimal postoperative complications, mitigating the risk of excessive bone removal and damage to adjacent structures.

Clinical and imaging analysis of 22 cases of supernumerary teeth in the mandibular region

PURPOSE

This study aimed to describe clinical and imaging analysis of supernumerary teeth in the mandibular region of 22 cases.

STUDY DESIGN

Retrospective study.

METHODS

This study enrolled patients diagnosed with supernumerary teeth who underwent cone beam computed tomography (CBCT) at Stomatology Hospital of Xi'an Jiaotong University from August 2016 to September 2022. Participants included individuals aged 7-29 years of both genders. The following variables were examined: number of supernumerary teeth, location, shape, direction, length, relationship with adjacent teeth and surrounding anatomical structures, and secondary effects.

RESULTS

Out of 236 subjects, 22 (6.02%) were found to have supernumerary teeth in the mandibular region, with a total of 62 teeth identified. The male-to-female ratio was 5:6. Most supernumerary teeth were located in the lingual side of the mandibular region, particularly in the 34-35 tooth area (21.66%), followed by the 44-45 tooth region. The vast majority of supernumerary teeth (96.77%) were impacted, and more than half (51.67%) were located near the mental nerve canal. The average length of the supernumerary teeth was 10.5 mm. While no primary complications were observed, some secondary symptoms were noted, such as the ectopic eruption of adjacent teeth and crowding of permanent teeth.

CONCLUSION

The supernumerary teeth in the mandibular area have regional characteristics, which can provide for clinical diagnosis and treatment. CBCT can accurately analyze the location of supernumerary teeth and their secondary effects, and provides the treatment plan on that basis.

Post-surgical complications of supernumerary teeth in the mandibular premolar area: A systematic review

In the mandibular premolar area, supernumerary teeth are a rare disorder that are rarely documented in the literature. The purpose of this study was to evaluate the post-surgical problems associated with the buccal and lingual techniques used to treat the extra teeth in this area. Using PubMed, PubMed Central, Science Direct, Cochrane, Wiley, and manual search, a thorough search was done to locate and identify cases and case series with extra teeth in the mandibular premolar region. For every study that was included, data on the surgical technique and postoperative problems were documented. Seven studies involving 90 patients were included. Supernumerary teeth in the mandibular premolar region were predominantly found in male patients (65.55 %), with most cases occurring in the right mandibular region (77.16 %). Postoperative complications after removing supernumerary teeth using buccal and lingual approaches were similar, with only one complication reported among the 90 cases reviewed. Although the findings suggest that surgical management of supernumerary teeth in the mandibular premolar region is relatively safe, caution is advised due to the limited sample size. Detailed pre-operative evaluation, a comprehensive treatment plan, and regular follow-up can minimize postoperative complications.

Human diprosopus: Case report of a rare congenital abnormality

Diprosopus is a congenital anomaly in which partial or complete duplication of craniofacial structures occurs. Because it is rare, the mortality rate is high, and information concerning this anomaly is scarce. This study describes a case of human diprosopus in a 9-year-old male individual, who has severe complications associated with the central nervous, cardiovascular, respiratory, and digestive systems. Since birth, he has been monitored in a specialized hospital environment, where he has undergone several surgeries and multidisciplinary treatments. Regarding the craniofacial aspects, he had agenesis of the corpus callosum, floor of the nasal cavity, and floor of the anterior cranial fossa, in addition to the presence of bone dysplasia, ocular hypertelorism and cleft palate with nasal and oral teratoma. Regarding dental characteristics, the patient has duplication of the maxilla, mandible, tongue, and some teeth. After complementary imaging exams, several supernumerary teeth were found, with some being impacted and in complex regions, with an indication for extraction due to the risks of impaction, irruptive deviation, root resorption, and associated cystic or tumoral lesions. Because of the numerous complications, knowledge, and preparation of the entire team is necessary for the correct management of the case.

Investigation of the fungiform papillae number in children with tooth number anomalies

OBJECTIVE

This cross-sectional study investigated the association between fungiform papillae (FP) numbers and tooth number anomalies in children, considering variables related to hypodontia and hyperdontia. The aim was to explore this association while adjusting for age and sex differences.

MATERIALS AND METHODS

A total of 144 children (aged 8-10) were categorized into hypodontia (n = 48), hyperdontia (n = 48), and control groups (n = 48). Clinical and radiographic diagnoses were used to classify tooth number anomalies. Hypodontia was categorized by number and location, while hyperdontia was categorized by number, shape, and location. FP were assessed using the Denver Papillae Protocol. Data analyses were performed using NCSS software, with p < 0.05 considered statistically significant.

RESULTS

The hypodontia group (22.5 ± 8.4) exhibited significantly lower FP than the control group (30.4 ± 9.2) and the hyperdontia group (27.9 ± 7.8) (p < 0.0005, p = 0.003, respectively). No significant difference existed between the hyperdontia and control groups. FP numbers in hypodontia subgroups showed no significant differences based on teeth agenesis numbers or locations. Similarly, hyperdontia subgroup analyses revealed no significant differences in FP numbers based on supernumerary teeth shapes (supplemental, conical, tuberculoid, paramolar) or the numbers of supernumerary teeth.

CONCLUSIONS

The lower FP numbers in children with hypodontia suggested an association between teeth and FP number. However, the non-significant difference in FP numbers with hyperdontia underscored the complexity of tooth development, warranting further investigations.

CLINICAL RELEVANCE

Children with hypodontia may exhibit distinct FP numbers compared to those without tooth number anomalies.

Supernumerary Tooth Patterns in Non-Syndromic White European Subjects

Supernumerary teeth form at an incidence of about 3% in the population, with differences among races and various clinical consequences. Information on detailed patterns, and especially on white subjects, is scarce in the literature. Therefore, we aimed to investigate the patterns of non-syndromic permanent supernumerary teeth in a white European population. A record review was performed in different orthodontic clinics and identified 207 eligible individuals with 258 supernumerary teeth. Approximately 80% of the subjects had one supernumerary tooth, while 15% had two. Supernumerary tooth formation was more often evident in males (male/female: 1.65). However, there was no sexual dimorphism in its severity. The following pattern sequences, with decreasing prevalence order, were observed in the maxilla: 21 > 11 > 12 > 18 > 28 and in the mandible: 34 > 44 > 35 > 45 > 42. Supernumerary teeth were most often unilaterally present, without sexual dimorphism. In the maxilla, they were more often anteriorly present, whereas in the mandible, an opposite tendency was observed. Supernumerary teeth were consistently more often observed in the maxilla than in the mandible; 74% were impacted, 80% had normal orientation (13% horizontal, 7% inverted), and 53% had normal size. The present thorough supernumerary tooth pattern assessment enables a better understanding of this condition with clinical, developmental, and evolutionary implications.

Pediatric Molar Hyperdontia: A Descriptive Case Report

Background

Hypergenetic molars are uncommon in children and adolescents. Furthermore, the presence of multiple eumorphic supernumerary molars (SNMs) in children is sporadic. The author, therefore, reports a nonsyndromic case of multiple supplemental SNMs in a child.

Case description

A ten year old boy primarily complaining of cheek biting was found to have six molars on the maxillary left quadrant. Following investigations and case discussion, four molars and fibroma were surgically removed under general anesthesia.

Discussion

This paper discusses the prevalence and management of SNMs in the pediatric population while documenting the first case of multiple eumorphic SNMs in the mixed dentition.

How to cite this article

Venkatesh SP. Pediatric Molar Hyperdontia: A Descriptive Case Report. Int J Clin Pediatr Dent 2023;16(5):763-768.

The Role of Artificial Intelligence in the Accurate Diagnosis and Treatment Planning of Non-Syndromic Supernumerary Teeth: A Case Report in a Six-Year-Old Boy

Hyperdontia can cause numerous aesthetic and functional problems. The diagnosis is made radiologically, and the most commonly used radiological method is orthopantomography, while CBCT is also used. CBCT has the advantage of being three-dimensional. Artificial Intelligence is widely used in medicine and dentistry, and it can create a specific algorithm to aid in diagnosis and suggest therapeutic procedures. In a case report, a 6-year-old boy was diagnosed with a supernumerary tooth between the upper central incisors. Orthopantomography revealed another impacted supernumerary tooth, and the patient was referred for CBCT. A platform for analyzing dental images, based on artificial intelligence, Diagnocat (Diagnocat Inc., San Francisco, CA, USA), was used for analysis and the AI system identified the supernumerary teeth and provided a complete plan for treatment. The use of AI in dentistry allows for faster and more accurate diagnosis and treatment planning.

Tooth Migration in a Female Patient with Hyperdontia: 11-Year Follow-Up Case Report

We described an 11-year follow-up of a patient with a non-syndrome multiple supernumerary teeth who had one extra tooth in the maxilla and four additional premolars in the mandible. Together with an additional distal migration of the second lower right premolar to the ramus of the mandible that also occurred, it comprises a unique combination of conditions that were not previously presented in the literature. We showed the significance of routine X-rays in cases of hyperdontia since the additional teeth may develop later than expected and the patient may not experience any symptoms.

Heterozygous Variants in FREM2 Are Associated with Mesiodens, Supernumerary Teeth, Oral Exostoses, and Odontomas

BACKGROUND

Supernumerary teeth refer to extra teeth that exceed the usual number of dentitions. A mesiodens is a particular form of supernumerary tooth, which is located in the premaxilla region. The objective of the study was to investigate the genetic etiology of extra tooth phenotypes, including mesiodens and isolated supernumerary teeth.

METHODS

Oral and radiographic examinations and whole-exome sequencing were performed on every patient in our cohort of 122 patients, including 27 patients with isolated supernumerary teeth and 94 patients with mesiodens. A patient who had multiple supernumerary teeth also had odontomas.

RESULTS

We identified a novel (c.8498A>G; p.Asn2833Ser) and six recurrent (c.1603C>T; p.Arg535Cys, c.5852G>A; p.Arg1951His, c.6949A>T; p.Thr2317Ser; c.1549G>A; p.Val517Met, c.1921A>G; p.Thr641Ala, and c.850G>C; p.Val284Leu) heterozygous missense variants in FREM2 in eight patients with extra tooth phenotypes.

CONCLUSIONS

Biallelic variants in FREM2 are implicated in autosomal recessive Fraser syndrome with or without dental anomalies. Here, we report for the first time that heterozygous carriers of FREM2 variants have phenotypes including oral exostoses, mesiodens, and isolated supernumerary teeth.

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

The activation of Wnt/β-catenin signalling is a prerequisite for odontogenesis. APC, a member of the AXIN-CK1-GSK3β-APC β-catenin destruction complex, functions to modulate Wnt/β-catenin signalling to establish regular teeth number and positions. APC loss-of-function mutations are associated with the over-activation of WNT/β-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 β-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.

A Third Supernumerary Tooth Occurring in the Same Region: A Case Report

The presence of a supernumerary tooth is one of the most common dental anomalies, and surgical treatment is often required to address this anomaly. Moreover, it may lead to malocclusion, and long-term follow-up is important to monitor its status. A 4-year-and-11-month-old boy was referred to our hospital for dental caries treatment. At 5 years and 5 months of age, a radiographic examination showed a supernumerary tooth (first supernumerary tooth) near the permanent maxillary left central incisor, and it was extracted 6 months later. Eighteen months after the extraction of the first supernumerary tooth, a new supernumerary tooth (second supernumerary tooth) was detected in the same region, which was extracted when the patient was aged seven years and seven months. Seven months later, another supernumerary tooth (third supernumerary tooth) was detected and extracted immediately. However, the permanent maxillary left central incisor did not erupt spontaneously even after 6 months. Therefore, surgical exposure was performed, and the central incisor erupted into the oral cavity. This report describes our experience with this patient with three metachronous supernumerary teeth and their management until the eruption of the permanent tooth. This report highlights the importance of long-term follow-up after supernumerary tooth extraction until the permanent teeth in that region have erupted completely.

Tooth number abnormality: from bench to bedside

Tooth number abnormality is one of the most common dental developmental diseases, which includes both tooth agenesis and supernumerary teeth. Tooth development is regulated by numerous developmental signals, such as the well-known Wnt, BMP, FGF, Shh and Eda pathways, which mediate the ongoing complex interactions between epithelium and mesenchyme. Abnormal expression of these crutial signalling during this process may eventually lead to the development of anomalies in tooth number; however, the underlying mechanisms remain elusive. In this review, we summarized the major process of tooth development, the latest progress of mechanism studies and newly reported clinical investigations of tooth number abnormality. In addition, potential treatment approaches for tooth number abnormality based on developmental biology are also discussed. This review not only provides a reference for the diagnosis and treatment of tooth number abnormality in clinical practice but also facilitates the translation of basic research to the clinical application.

Taurodontism in simultaneous existence with multiple supernumerary teeth: A case report

Supernumerary teeth and taurodontism are both common dental anomalies when found as isolated entities. However, simultaneous presence in the same individual without a syndrome is rarely reported in the literature. This case report describes a 20-year-old non-syndromic male with multiple supernumerary teeth in association with multiple molar and premolar taurodonts and no family history of genetic predisposing factors. Taurodontism was measured and confirmed through cone-beam computed tomography for accuracy of the classification. Early diagnosis with the aid of radiographic imaging and persistent follow-up are crucial to treatment.

The heritability of vocal tract structures estimated from structural MRI in a large cohort of Dutch twins

While language is expressed in multiple modalities, including sign, writing, or whistles, speech is arguably the most common. The human vocal tract is capable of producing the bewildering diversity of the 7000 or so currently spoken languages, but relatively little is known about its genetic bases, especially in what concerns normal variation. Here, we capitalize on five cohorts totaling 632 Dutch twins with structural magnetic resonance imaging (MRI) data. Two raters placed clearly defined (semi)landmarks on each MRI scan, from which we derived 146 measures capturing the dimensions and shape of various vocal tract structures, but also aspects of the head and face. We used Genetic Covariance Structure Modeling to estimate the additive genetic, common environmental or non-additive genetic, and unique environmental components, while controlling for various confounds and for any systematic differences between the two raters. We found high heritability, h2, for aspects of the skull and face, the mandible, the anteroposterior (horizontal) dimension of the vocal tract, and the position of the hyoid bone. These findings extend the existing literature, and open new perspectives for understanding the complex interplay between genetics, environment, and culture that shape our vocal tracts, and which may help explain cross-linguistic differences in phonetics and phonology.

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.

Dental anomalies in non-syndromic orofacial clefts: a clinical approach

Orofacial clefts (OC) represent some of the most common congenital malformations and affect multiple structures in the craniofacial region. There are a wide range of morphological OC types within the spectrum of both non-syndromic OC (NSOC) and syndromic OC, including cleft lip (CL); cleft lip and palate (CLP) and cleft palate (CP). Here, we describe the most frequent dental anomalies seen in the permanent dentition of individuals with NSOC, comparing them between the three main cleft types (CL, CLP, CP). We present these findings from the perspective of prevalence relating to each anomaly, as well as the clinical characteristics and potential impact in the rehabilitation process. The investigation of dental anomalies associated with NSOC is important, helping to expand the phenotypic characterization of NSOC, improve initial diagnostics and establish appropriate rehabilitation and counseling.

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.

Revitalizing mouse diphyodontic dentition formation by inhibiting the sonic hedgehog signaling pathway

BACKGROUND

Tooth regeneration depends on the longevity of the dental epithelial lamina. However, the exact mechanism of dental lamina regression has not yet been clarified. To explore the role of the Sonic hedgehog (Shh) signaling pathway in regression process of the rudimentary successional dental lamina (RSDL) in mice, we orally administered a single dose of a Shh signaling pathway inhibitor to pregnant mice between embryonic day 13.0 (E13.0) and E17.0.

RESULTS

We observed that the Shh signaling pathway inhibitor effectively inhibited the expression of Shh signaling pathway components and revitalized RSDL during E15.0-E17.0 by promoting cell proliferation. In addition, mRNA-seq, reverse transcription plus polymerase chain reaction (RT-qPCR), and immunohistochemical analyses indicated that diphyodontic dentition formation might be related to FGF signal up-regulation and the Sostdc1-Wnt negative feedback loop.

CONCLUSIONS

Overall, our results indicated that the Shh signaling pathway may play an initial role in preventing further development of mouse RSDL in a time-dependent manner.

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.

Molar incisor hypomineralisation and dental anomalies: A random or real association?

BACKGROUND

Clinical observations suggest molar incisor hypomineralisation (MIH) may present with other dental conditions.

AIMS

The study aimed to determine the prevalence and variety of dental anomalies in children presenting with MIH.

DESIGN

A convenience sample of children referred to a UK dental hospital was recruited. Orthopantogram radiographs, taken as part of routine care, were assessed for dental anomalies. Two calibrated examiners reviewed the films separately and determined the presence and character of anomalies.

RESULTS

Radiographs were obtained from 101 patients, with an age range of 6-15 years. Co-existing hypodontia was identified in 12%, with lower second premolars being the most commonly missing teeth. Concurrent ectopic first permanent molars were identified in 8%, and infraocclusion of one or more primary molars was identified in 9%. Abnormal morphology was found in 9%, including macrodont and microdont teeth. In total, 29% of patients had an associated dental anomaly. Examiners had perfect agreement using Cohen's kappa coefficient.

CONCLUSION

This high prevalence of dental anomalies, particularly hypodontia, in children with MIH is a novel and clinically important finding. Further research is warranted considering the potential implications for assessment and treatment planning.

Analysis of the distribution of supernumerary teeth and the characteristics of mesiodens in Bengbu, China: a retrospective study

OBJECTIVES

To evaluate the distribution of supernumerary teeth (ST) and the characteristics of mesiodens.

METHODS

Panoramic radiographs of 48,700 outpatients were used to assess the distribution of ST. A total of 142 cone beam computed tomography (CBCT) images were used to evaluate the characteristics of mesiodens.

RESULTS

A total of 1.24% of individuals aged from 1 to 98 years were diagnosed with ST among 48,700 outpatients, and males had a higher percentage of ST than females (2.94:1); patients aged 6-12 years were the most frequently diagnosed. More females had ST impacted in bone than males. The percentages of patients with 1 and 2 ST were 0.949 and 0.290%, respectively. The most frequent location, crown direction, and morphology of mesiodens were palatal, inverted, and conical, respectively. The tooth lengths of mesiodens in males and of erupted mesiodens were longer than that those in females and of unerupted mesiodens, respectively. Inverted mesiodens had the shortest tooth length compared with vertical and horizontal mesiodens. These results were statistically significant.

CONCLUSIONS

The distribution of ST and mesiodens were both related to gender, and patients aged 6-12 years were the most frequently detected. The length of the mesiodens was associated with the growth direction and mesiodens eruption.

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.

Teeth: Small but Mighty and Mighty Important. A Comprehensive Review of Children's Dental Health for Primary Care Clinicians

Healthy teeth allow us to eat and stay well-nourished. Although primary care clinicians receive limited training about teeth, given the common nature of dental problems, it is important that they understand and recognize normal and abnormal dental conditions and can implement primary and secondary prevention of dental conditions in their practice. PubMed has been used to search the scientific literature for evidence on the following topics: normal dental development, dental abnormalities, malocclusion, teething, dental caries and related epidemiology and prevention, fluoride, dental injury and its management and prevention; and identification, prevention and treatment of gingivitis and periodontal disease. Literature review relied on randomized controlled trials, meta-analyses, systematic reviews, and Cochrane reviews when relevant and available. Other sources of evidence included cohort and case-control studies. Consensus statements and expert opinion were used when there was a paucity of high-quality research studies. The literature has been synthesized on these topics to make them relevant to pediatric primary care clinicians, and as available, the strength of evidence has been characterized when making clinical recommendations.

Process of ectopic tooth formation in the maxillary sinus: follow-up observation of one case

Objective

This study was performed to investigate the process of ectopic tooth formation.

Methods

A patient with an ectopic tooth was followed for 6 years. The tooth size and mineralization were evaluated by paranasal sinus computed tomography every 3 years.

Results

The ectopic tooth was present in the nasal crest of the maxilla and did not change significantly during the 6-year follow-up period. However, the patient developed a new ectopic tooth in the maxillary sinus (ETm). This tooth, located in the posterior wall of the left maxillary sinus, initially appeared as a small region of soft tissue on computed tomography. After 3 years, the area of mixed density had significantly increased, and some of it had significantly mineralized to form an ETm. After 6 years, the ETm had further mineralized and enlarged in situ. The width between the left and right sides of the ETm in 2018 (9.08 ± 2.09 mm) was significantly larger than that in 2015 (7.51 ± 2.18 mm), indicating that ETm formation is a gradual process of mineralization.

Conclusion

Ectopic teeth can gradually form by in situ mineralization after adolescence, suggesting that ectopic teeth are genetically regulated and result from a programmed formation process occurring at a specific time point.

Advances of Wnt signalling pathway in dental development and potential clinical application

Wnt signalling pathway is widely studied in many processes of biological development, like embryogenesis, tissue homeostasis and wound repair. It is universally known that Wnt signalling pathway plays an important role in tooth development. Here, we summarized the function of Wnt signalling pathway during tooth initiation, crown morphogenesis, root formation, and discussed the therapeutic potential of Wnt modulators.

Third Dentition Is the Main Cause of Premolar Supernumerary Tooth Formation

While the prevalence of supernumerary teeth (ST) is high in permanent dentition, the etiology of ST in humans remains unclear. However, multiple murine models of ST have elaborated on dated mechanisms traditionally ascribed to ST etiology: one involves the rescue of rudimental teeth, and the second considers the contribution of odontogenic epithelial stem cells. It remains unclear whether these mechanisms of ST formation in mice are applicable to humans. The third dentition is usually regressed apoptotic-that is, the teeth do not completely form in humans. Recently, it was suggested that ST result from the rescue of regression of the third dentition in humans. The present investigation evaluates the proportion of collected general ST cases that evinced a third dentition based on the clinical definition of ST derived from the third dentition. We also investigated the contribution of SOX2-positive odontogenic epithelial stem cells to ST formation in humans. We collected 215 general ST cases from 15,008 patients. We confirmed that the general characteristics of the collected ST cases were similar to the results from previous reports. Of the 215 cases, we narrowed our analysis to the 78 patients who had received a computed tomography scan. The frequency of ST considered to have been derived from the third dentition was 26 out of 78 cases. Evidence of a third dentition was especially apparent in the premolar region, was more common in men, and was more likely among patients with ≥3 ST. SOX2-positive odontogenic epithelial stem cells within the surrounding epithelial cells of developing ST were observed in non-third dentition cases and not in third dentition cases. In conclusion, the third dentition is the main cause of ST in humans. The odontogenic epithelial stem cells may contribute to ST formation in cases not caused by a third dentition.

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.

Electronic supplementary material

The online version of this article (10.1186/s12903-019-0788-3) contains supplementary material, which is available to authorized users.

Supernumerary teeth in the bilateral buccal space: a rare case

Supernumerary teeth are usually found in the alveolus, but may occasionally be sited in unusual places. We report a rare case of a patient who presented with two supernumerary teeth in the bilateral buccal space.