Enamel hypoplasia is an exclusive ectodermal disturbance, related to alterations in the organic enamel matrix which can cause white flecks, narrow horizontal bands, lines of pits, grooves, and discoloration of the teeth. It can result in compromised oral health that causes physiological and psychological disturbances. Management of enamel hypoplasia not only includes esthetic and functional rehabilitation of the patient but also requires a positive rapport building with the patient due to psychosocial issues. The present case reports elucidate step-by-step management of 16-year-old female patient who presented with localized enamel hypoplasia with severely decayed anterior teeth, poor dental esthetics, and oligodontia of the lower teeth.

OBJECTIVE: To investigate the prevalence of tooth agenesis and associated dental anomalies in Latvian adolescent dental patients and compare it to other European countries.
METHODS: Cross-sectional study of 2692 11-to-14-year-old patients (39.9% males and 60.1% females) attending Riga Stradins University Institute of Stomatology with panoramic radiographs taken between August 2020 and September 2021. Patients with any genetic syndromes were excluded. Data on tooth agenesis (excluding third molars) and other dental anomalies were recorded.
RESULTS: The prevalence of tooth agenesis in Latvian adolescent dental patients was 9.3% with no statistically significant difference between genders (χ2 test, p = 0.472). The most commonly missing teeth were mandibular second premolars, followed by upper lateral incisors and upper second premolars. There was a statistically significant association with the presence of other dental anomalies in tooth agenesis patients (p < 0.001).
CONCLUSIONS: This study found that the prevalence of non-syndromic tooth agenesis in Latvian adolescent dental patients was 9.3% with no statistically significant differences between the genders. Patients with tooth agenesis have a statistically significant possibility of the presence of other dental anomalies (p < 0.001).

Dental agenesis is one of the most common developmental anomalies in humans and it is frequently associated with several other oral abnormalities. The present case describes non-familial agenesis of permanent teeth in a twenty-one-year-old boy with no apparent systemic abnormalities. The treatment included a personalized and interdisciplinary approach involving endodontics, orthodontics, implant-supported restorations and prosthetic treatments. The treatment plan was thoroughly elaborated using photographic analysis, study models, orthopantomogram, CBCT and cephalograms. Virtual smile design, diagnostic waxing and mock-ups previsualized the treatment objectives. The edentulous spaces were reconstructed by inserting dental implants and monolithic zirconia implant-supported restorations. The final results showed a highly esthetic and functional rehabilitation. Periodic check-ups have shown that the stability of the result is well maintained and that the implant-supported restorations are an optimal solution for patients with multiple anodontia.

Hypodontia, i.e., missing one or more teeth, is a relatively common human disease; however, oligodontia, i.e., missing six or more teeth, excluding the third molars, is a rare congenital disorder. Many genes have been shown to cause oligodontia in non-syndromic or syndromic conditions. In this study, we identified two novel PAX9 mutations in two non-syndromic oligodontia families. A mutational analysis identified a silent mutation (NM_006194.4: c.771G>A, p.(Gln257=)) in family 1 and a frameshift mutation caused by a single nucleotide duplication (c.637dup, p.(Asp213Glyfs*104)) in family 2. A minigene splicing assay revealed that the silent mutation resulted in aberrant pre-mRNA splicing instead of normal splicing. The altered splicing products are ones with an exon 4 deletion or using a cryptic 5\' splicing site in exon 4. Mutational effects were further investigated using protein expression, luciferase activity assay and immunolocalization. We believe this study will not only expand the mutational spectrum of PAX9 mutations in oligodontia but also strengthen the diagnostic power related to the identified silent mutation.

UNASSIGNED: To analyse the pathogenic genes in a patient with hypohidrotic ectodermal dysplasia (HED) and explore the relationship between pathogenic genes and the oligodontia phenotype.
UNASSIGNED: Clinical data and peripheral blood were collected from a patient with HED. Pathogenic genes were analysed by whole-exon sequencing (WES) and verified by Singer sequencing. The secondary and tertiary structures of the variant proteins were predicted to analyse their toxicity.
UNASSIGNED: The patient exhibited a severe oligodontia phenotype, wherein only two deciduous canines were left in the upper jaw. WES revealed a hemizygous EDA variant c.466C > T p.(Arg156Cys) and a novel heterozygous EVC2 variant c.1772T > C p.(Leu591Ser). Prediction of the secondary and tertiary structures of the EDA variant p.(Arg156Cys) and EVC2 variant p.(Leu591Ser) indicated impaired function of both molecules.
UNASSIGNED: The patient demonstrated a more severe oligodontia phenotype when compared with the other patients caused by the EDA variant c.466C > T. Since Evc2 is a positive regulator of the Sonic Hedgehog (Shh) signal pathway, we speculated that the EVC2 variant p.(Leu591Ser) may play a synergistic role in the oligodontia phenotype of HED, thereby exacerbating the oligodontia phenotype. Knowledge of oligodontia caused by multiple gene variants is of great significance for understanding individual differences in oligodontia phenotypes.

The aim of this systematic review was to describe the clinical and genetic features of syndromes showing oligodontia as a sign. The review was performed according to the PRISMA 2020 checklist guidelines, and the search was conducted using PubMed, Scopus, Lilacs, Web of science, Livivo, and EMBASE and supplemented by a gray literature search on Google Scholar and ProQuest, applying key terms relevant to the research questions. The systematic review identified 47 types of syndromes in 83 studies, and the most common was hypohidrotic ectodermal dysplasia, which was reported in 24 patients in 22 studies. Other common syndromes that reported oligodontia included Axenfeld-Rieger syndrome, Witkop\'s syndrome, Ellis-van Creveld syndrome, blepharocheilodontic syndrome, and oculofaciocardiodental syndrome. The X-linked mode of inheritance was the most reported (n = 13 studies), followed by the autosomal dominant (n = 13 studies). The review describes the main syndromes that may have oligodontia as a clinical sign and reinforces the need for orodental-facial examining for adequate diagnosis and treatment of the affected patients. Molecular analysis in order to better understand the occurrence of oligodontia is imperative.

Tooth agenesis, one of the most common developmental defects in humans, not only impairs oral function but can also lead to craniofacial deformities. Bibliometric analysis can reveal significant shifts in research and publishing trends within specific fields. This study aims to provide a comprehensive overview of the research hotspots in tooth agenesis and predict future trends through bibliometric analysis. We searched for English-language publications related to tooth agenesis from 2001 to 2021 on the Web of Science. The publications were limited to original and review articles, and bibliometric parameters such as publication year, country, institution, author, journal, citations, and keywords were extracted and analyzed using VOSviewer, Microsoft Excel 2010, and CiteSpace. A total of 2,287 papers were ultimately selected. The results show that the USA holds a leading position in the field of tooth agenesis research. A total of 9,803 authors participated in these studies, with Alexandre R Vieira from the USA being the most prolific and most cited author. This study indicates that multidisciplinary management has become the consensus first choice for treating dental agenesis. Gene mutations related to tooth agenesis continue to be a research hotspot attracting scholarly attention. Exploring the relationship between tooth agenesis and cancer may be a future research direction. These findings contribute to potential collaborations among experts in future research on the genetic causes of tooth agenesis and tumor development and to assist the scientific community by identifying research gaps in this field.

Background: The risk of palatally displaced canines (PDCs) rises in patients with tooth agenesis. The orthodontic extrusion and alignment of PDCs require adequate anchorage to enable tooth movement and control the side effects. There is no paper presenting treatment in the case of severe oligodontia with simultaneous PDCs and the use of mini-implants (MIs) for their orthodontic extrusion. Case presentation: A 15-year-old patient presented with non-syndromic oligodontia and bilateral PDCs. Cone beam computed tomography revealed that both PDCs were in proximity to the upper incisors\' roots. There was no evident external root resorption of the incisors. The \"canines first\" approach was chosen. MIs were used both as direct and indirect anchorage. First, the extrusive forces of cantilevers were directed both occlusally and distally. Next, the buccal directions of forces were implemented. Finally, fixed appliances were used. PDCs were extruded, aligned, and torqued. Proper alignment and occlusion were achieved to enable further prosthodontic restorations. Conclusions: The use of MIs made it possible to avoid collateral effects, reduce the risk of complications, and treat the patient effectively. MIs provide adequate anchorage in demanding cases. The use of MIs for the extrusion of PDCs made it possible to offer this treatment option to patients with severe oligodontia. The presented protocol was effective and served to circumvent treatment limitations associated with an inadequate amount of dental anchorage and a high risk of root resorption.

BACKGROUND: Ectodermal dysplasias are inherited disorders, which are characterized by congenital defects in two or more ectodermal structures such as skin, sweat glands, hair, nails, teeth, and mucous membranes.
METHODS: Here, we describe a new observation of significant oligodontia in a female patient with the EDA gene variant c.742-2A>G.
RESULTS: The results strongly suggest that the EDA gene variant c.742-2A>G is pathogenic. The oligodontia in the proband was exceptionally severe.
CONCLUSIONS: We demonstrate that the very rare splice acceptor variant EDA c.742-2A>G is associated with severe oligodontia even in females. Our study points that this variant is pathogenic. An early identification of this variant is crucial for planning adequate treatment and follow-up in time by a multidisciplinary team.

BACKGROUND: WNT signaling is pivotal in embryogenesis and tissue homeostasis. Aberrant WNT signaling, due to mutations in components of this pathway, contributes to the development and progression of human cancers, including colorectal cancer. AXIN2, encoded by the AXIN2 gene, is a key negative regulator and target of the canonical WNT signaling pathway. Germline mutations in AXIN2 are associated with absence of permanent teeth (hypo- and oligodontia) and predisposition to gastrointestinal polyps and cancer. The limited number of patients makes an accurate genotype-phenotype analysis currently challenging.
METHODS: We present the case of a 55-year-old male with colorectal polyposis and hypodontia. Genetic testing confirmed a novel frameshift germline mutation in exon 8 of the AXIN2 gene. In addition, we provide an updated overview of germline AXIN2 mutations reported in literature.
CONCLUSIONS: Although the number of missing teeth is less severe in our patient than in some previously reported cases, our findings provide additional evidence that missing teeth and gastrointestinal neoplasia are associated with rare pathogenic AXIN2 germline mutations.