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Developmental Cell Oct 2023Tooth enamel secreted by ameloblasts (AMs) is the hardest material in the human body, acting as a shield to protect the teeth. However, the enamel is gradually damaged...
Tooth enamel secreted by ameloblasts (AMs) is the hardest material in the human body, acting as a shield to protect the teeth. However, the enamel is gradually damaged or partially lost in over 90% of adults and cannot be regenerated due to a lack of ameloblasts in erupted teeth. Here, we use single-cell combinatorial indexing RNA sequencing (sci-RNA-seq) to establish a spatiotemporal single-cell census for the developing human tooth and identify regulatory mechanisms controlling the differentiation process of human ameloblasts. We identify key signaling pathways involved between the support cells and ameloblasts during fetal development and recapitulate those findings in human ameloblast in vitro differentiation from induced pluripotent stem cells (iPSCs). We furthermore develop a disease model of amelogenesis imperfecta in a three-dimensional (3D) organoid system and show AM maturation to mineralized structure in vivo. These studies pave the way for future regenerative dentistry.
Topics: Humans; Ameloblasts; Amelogenesis; Dental Enamel; Odontogenesis; Tooth
PubMed: 37582367
DOI: 10.1016/j.devcel.2023.07.013 -
L' Orthodontie Francaise Nov 2023The precise diagnosis of dental structural anomalies is an essential step preceding our restorative and orthodontic therapies. Indeed, first of all, it is necessary to...
INTRODUCTION
The precise diagnosis of dental structural anomalies is an essential step preceding our restorative and orthodontic therapies. Indeed, first of all, it is necessary to identify the type of structural anomaly and to determine if it is an isolated or a syndromic form: the dental anomaly could be included in a more complex clinical picture combining other clinical signs. Moreover, the establishment of the diagnosis will allow the practitioner to adapt his clinical protocol according to the observed dental structure anomaly. The choice of the bonding material, the type of preparation (no prep, prep less, complete eviction), and the application of a deproteinization protocol with sodium hypochlorite depend to the structural defect.
MATERIAL AND METHOD
The diagnosis of dental structural anomalies is based on several key points described in this article in order to facilitate the practitioner's diagnostic approach.
CONCLUSION
The diagnosis of amelogenesis or dentinogenesis imperfecta should justify the search for other signs to determine whether the anomaly of tooth structure is isolated or syndromic.
Topics: Humans; Amelogenesis; Dental Materials; Sodium Hypochlorite
PubMed: 37930342
DOI: 10.1684/orthodfr.2023.134 -
Matrix Biology : Journal of the... Aug 2024Extracellular matrix proteins play crucial roles in the formation of mineralized tissues like bone and teeth via multifunctional mechanisms. In tooth enamel,... (Review)
Review
Extracellular matrix proteins play crucial roles in the formation of mineralized tissues like bone and teeth via multifunctional mechanisms. In tooth enamel, ameloblastin (Ambn) is one such multifunctional extracellular matrix protein implicated in cell signaling and polarity, cell adhesion to the developing enamel matrix, and stabilization of prismatic enamel morphology. To provide a perspective for Ambn structure and function, we begin this review by describing dental enamel and enamel formation (amelogenesis) followed by a description of enamel extracellular matrix. We then summarize the established domains and motifs in Ambn protein, human amelogenesis imperfecta cases, and genetically engineered mouse models involving mutated or null Ambn. We subsequently delineate in silico, in vitro, and in vivo evidence for the amphipathic helix in Ambn as a proposed cell-matrix adhesive and then more recent in vitro evidence for the multitargeting domain as the basis for dynamic interactions of Ambn with itself, amelogenin, and membranes. The multitargeting domain facilitates tuning between Ambn-membrane interactions and self/co-assembly and supports a likely overall role for Ambn as a matricellular protein. We anticipate that this review will enhance the understanding of multifunctional matrix proteins by consolidating diverse mechanisms through which Ambn contributes to enamel extracellular matrix mineralization.
Topics: Humans; Animals; Dental Enamel Proteins; Amelogenesis; Amelogenesis Imperfecta; Mice; Dental Enamel; Extracellular Matrix; Amelogenin; Cell Adhesion
PubMed: 38815936
DOI: 10.1016/j.matbio.2024.05.007 -
Oral Diseases Sep 2023Amelogenesis imperfecta (AI) is one of the typical dental genetic diseases in human. It can occur isolatedly or as part of a syndrome. Previous reports have mainly... (Review)
Review
Amelogenesis imperfecta (AI) is one of the typical dental genetic diseases in human. It can occur isolatedly or as part of a syndrome. Previous reports have mainly clarified the types and mechanisms of nonsyndromic AI. This review aimed to compare the phenotypic differences among the hereditary enamel defects with or without syndromes and their underlying pathogenic genes. We searched the articles in PubMed with different strategies or keywords including but not limited to amelogenesis imperfecta, enamel defects, hypoplastic/hypomaturation/hypocalcified, syndrome, or specific syndrome name. The articles with detailed clinical information about the enamel and other phenotypes and clear genetic background were used for the analysis. We totally summarized and compared enamel phenotypes of 18 nonsyndromic AI with 17 causative genes and 19 syndromic AI with 26 causative genes. According to the clinical features, radiographic or ultrastructural changes in enamel, the enamel defects were basically divided into hypoplastic and hypomineralized (hypomaturated and hypocalcified) and presented a higher heterogeneity which were closely related to the involved pathogenic genes, types of mutation, hereditary pattern, X chromosome inactivation, incomplete penetrance, and other mechanisms.The gene-specific enamel phenotypes could be an important indicator for diagnosing nonsyndromic and syndromic AI.
Topics: Humans; Amelogenesis Imperfecta; Dental Enamel; Dental Enamel Hypoplasia; Dental Enamel Proteins; Phenotype
PubMed: 37154292
DOI: 10.1111/odi.14599 -
International Orthodontics Dec 2023The aim of this systematic review (Prospero CRD42022323188) is to investigate whether an association exists in patients with amelogenesis imperfecta (AI) between...
INTRODUCTION
The aim of this systematic review (Prospero CRD42022323188) is to investigate whether an association exists in patients with amelogenesis imperfecta (AI) between occlusal characteristics and genotype on the one hand and enamel structural phenotype on the other.
MATERIAL AND METHODS
Reports up to May 2023 assessing occlusion of individuals with AI were browsed in a systematic search using Medline, Embase, ISI Web of Science, and the grey literature. Randomised control trials, case control studies, and case series specifying both occlusion, assessed by cephalometric or clinical analysis, and genotype or dental phenotype in patients with AI were included without any age limitation. Two authors independently selected the publications and extracted the data in accordance with the PRISMA statement. The risk of bias was assessed with the Critical Appraisal Checklists from the Johanna Briggs Institute.
RESULTS
Twenty-five articles were chosen from the 261 results. Most of the included publications were case series (n=22) and case control studies (n=3). Thirteen studies reported both a genotype (ENAM, FAM83H, FAM20A, DLX3, CNMM4, WDR72) and occlusal diagnostic. The methodological quality of the studies was moderate. All AI phenotypes showed an open bite (OB) rate around 35%, except mixed form. The other malocclusions were not often mentioned. No correlation between occlusal phenotype and genotype or AI phenotype could be identified in patients with AI, as most studies had short occlusal descriptions and small sample sizes.
CONCLUSION
OB malocclusions were more frequently reported in AI. This review highlighted the need for a more accurate description of orofacial features associated with AI, to better clarify the role of amelogenesis genes in the regulation of craniofacial morphogenesis and identify patients requiring orthognathic surgery at an early stage.
Topics: Humans; Amelogenesis Imperfecta; Genotype; Phenotype; Dental Enamel; Malocclusion; Open Bite; Proteins
PubMed: 37494776
DOI: 10.1016/j.ortho.2023.100789 -
Journal of Dental Research Aug 2023Tooth enamel is generated by ameloblasts. Any failure in amelogenesis results in defects in the enamel, a condition known as amelogenesis imperfecta. Here, we report...
Tooth enamel is generated by ameloblasts. Any failure in amelogenesis results in defects in the enamel, a condition known as amelogenesis imperfecta. Here, we report that mice with deficient autophagy in epithelial-derived tissues ( and conditional knockout mice) exhibit amelogenesis imperfecta. Micro-computed tomography imaging confirmed that enamel density and thickness were significantly reduced in the teeth of these mice. At the molecular level, ameloblast differentiation was compromised through ectopic accumulation and activation of NRF2, a specific substrate of autophagy. Through bioinformatic analyses, we identified , , , , , and as candidate genes related to amelogenesis imperfecta and the NRF2-mediated pathway. To investigate the effects of the ectopic NRF2 pathway activation caused by the autophagy deficiency, we analyzed target gene expression and NRF2 binding to the promoter region of candidate target genes and found suppressed gene expression of , , , and but not of and . Taken together, our findings indicate that autophagy plays a crucial role in ameloblast differentiation and that its failure results in amelogenesis imperfecta through ectopic NRF2 activation.
Topics: Mice; Animals; Ameloblasts; Amelogenesis Imperfecta; X-Ray Microtomography; NF-E2-Related Factor 2; Amelogenesis; Mice, Knockout; Tumor Suppressor Proteins; Repressor Proteins
PubMed: 37249312
DOI: 10.1177/00220345231169220 -
Journal of Dentistry Jun 2024To summarize studies published between 2017 and 2023 examining the clinical diagnosis and restorative management of amelogenesis imperfecta (AI) in children and... (Review)
Review
OBJECTIVE
To summarize studies published between 2017 and 2023 examining the clinical diagnosis and restorative management of amelogenesis imperfecta (AI) in children and adolescents.
DATA
The review incorporated publications on clinical diagnosis, patient-reported outcomes, clinical trials, cohort studies, and case reports that included individuals below 19 years of age with non-syndromic AI.
SOURCES
A literature search was conducted across electronic databases, PubMed, Web of Science, and CINAHL, including papers published between 2017 and 2023. The search yielded 335 unique results, of which 38 were eligible for inclusion.
RESULTS
New evidence on the genetic background of AI makes it now advisable to recommend genetic testing to supplement a clinical AI diagnosis. The discussions of the dental profession and the public on social media do not always incorporate recent scientific evidence. Interview studies are finding that the impact of AI on quality of life is more severe than previously appreciated. New evidence suggests that single-tooth ceramic crowns should be the first choice of treatment. Due to incomplete reporting, case reports have been of limited value.
CONCLUSION
In young patients with AI symptoms of pain and hypersensitivity decreased, and aesthetics were improved following all types of restorative therapy. Resin composite restorations were mainly performed in cases with hypoplastic AI and mild symptoms. Single tooth ceramic crown restorations have a high success rate in all types of AI and can be used in young individuals with AI.
CLINICAL SIGNIFICANCE
Prosthetic rehabilitation in adolescents with severe AI is cost effective, improves esthetics, reduces tooth sensitivity, and improves oral health-related quality of life.
PubMed: 38909645
DOI: 10.1016/j.jdent.2024.105149 -
Nature Dec 2023Ameloblasts are specialized epithelial cells in the jaw that have an indispensable role in tooth enamel formation-amelogenesis. Amelogenesis depends on multiple...
Ameloblasts are specialized epithelial cells in the jaw that have an indispensable role in tooth enamel formation-amelogenesis. Amelogenesis depends on multiple ameloblast-derived proteins that function as a scaffold for hydroxyapatite crystals. The loss of function of ameloblast-derived proteins results in a group of rare congenital disorders called amelogenesis imperfecta. Defects in enamel formation are also found in patients with autoimmune polyglandular syndrome type-1 (APS-1), caused by AIRE deficiency, and in patients diagnosed with coeliac disease. However, the underlying mechanisms remain unclear. Here we show that the vast majority of patients with APS-1 and coeliac disease develop autoantibodies (mostly of the IgA isotype) against ameloblast-specific proteins, the expression of which is induced by AIRE in the thymus. This in turn results in a breakdown of central tolerance, and subsequent generation of corresponding autoantibodies that interfere with enamel formation. However, in coeliac disease, the generation of such autoantibodies seems to be driven by a breakdown of peripheral tolerance to intestinal antigens that are also expressed in enamel tissue. Both conditions are examples of a previously unidentified type of IgA-dependent autoimmune disorder that we collectively name autoimmune amelogenesis imperfecta.
Topics: Humans; Amelogenesis Imperfecta; Autoantibodies; Celiac Disease; Immunoglobulin A; Polyendocrinopathies, Autoimmune; Proteins; Ameloblasts; Dental Enamel; AIRE Protein; Antigens; Intestines
PubMed: 37993717
DOI: 10.1038/s41586-023-06776-0 -
Cureus Dec 2023Amelogenesis imperfecta (AI) is a rare genetic disorder affecting children and adults. Knowledge about AI is limited to clinical representation and radiographical... (Review)
Review
Amelogenesis imperfecta (AI) is a rare genetic disorder affecting children and adults. Knowledge about AI is limited to clinical representation and radiographical findings. Various treatments are provided to children with AI, yet no definitive treatment guideline has been suggested in the literature. This scoping review highlights the knowledge of the etiology and classification of AI and synthesizes these findings in a comprehensive review, focusing mainly on the various forms of AI in children and management with a restorative conservative approach. Five electronic databases, namely, PubMed, Google Scholar, Embase, Web of Science, and Scopus, were searched for the relevant articles. The search was performed in two phases: first for title and abstract, and second for full-text articles. The studies included in this scoping review were published from 2013 to August 2023. The data extraction was done on a customized sheet. A total of 33 studies were included in this review, of which 19 were reports and series, seven were observational, and seven were reviews. Most patients included in this review suffered from the hypoplastic type of AI (54%), followed by hypomatured (36%), and hypocalcified (10%). The treatment modalities explained were divided into the following three phases: temporary, transient, and permanent. Almost all included reports suggested the requirement for guidelines for treating AI among young children. This scoping review suggests the need for guidelines for treating AI in children. Moreover, pediatric dentists should prioritize early diagnosis and treatment and long-term follow-up for AI in children to effectively enhance the patient's psychological well-being and overall quality of life.
PubMed: 38179349
DOI: 10.7759/cureus.49968