Single-cell RNA-seq of in vitro expanded cells from cranial neural crest reveals a rare odontogenic sub-population.

Ecto-mesenchymal cells of mammalian tooth germ develops from cranial neural crest cells. These cells are recognised as a promising source for tooth development and regeneration. Despite the high heterogeneity of the neural crest, the cellular landscape of in vitro cultured cranial neural crest cells (CNCCs) for odontogenesis remains unclear. In this study, we used large-scale single-cell RNA sequencing to analyse the cellular landscape of in vitro cultured mouse CNCCs for odontogenesis. We revealed distinct cell trajectories from primary cells to passage 5 and identified a rare Alx3+/Barx1+ sub-population in primary CNCCs that differentiated into two odontogenic clusters characterised by the up-regulation of Pax9/Bmp3 and Lhx6/Dmp1. We successfully induced whole tooth-like structures containing enamel, dentin, and pulp under the mouse renal capsule using in vitro cultured cells from both cranial and trunk neural crests with induction rates of 26.7% and 22.1%, respectively. Importantly, we confirmed only cells sorted from odontogenic path can induce tooth-like structures. Cell cycle and DNA replication genes were concomitantly upregulated in the cultured NCCs of the tooth induction groups. Our data provide valuable insights into the cell heterogeneity of in vitro cultured CNCCs and their potential as a source for tooth regeneration.

The Essential Role of Proteoglycans and Glycosaminoglycans in Odontogenesis.

Tooth development and regeneration are regulated through a complex signaling network. Previous studies have focused on the exploration of intracellular signaling regulatory networks, but the regulatory roles of extracellular networks have only been revealed recently. Proteoglycans, which are essential components of the extracellular matrix (ECM) and pivotal signaling molecules, are extensively involved in the process of odontogenesis. Proteoglycans are composed of core proteins and covalently attached glycosaminoglycan chains (GAGs). The core proteins exhibit spatiotemporal expression patterns during odontogenesis and are pivotal for dental tissue formation and periodontium development. Knockout of core protein genes Biglycan, Decorin, Perlecan, and Fibromodulin has been shown to result in structural defects in enamel and dentin mineralization. They are also closely involved in the development and homeostasis of periodontium by regulating signaling transduction. As the functional component of proteoglycans, GAGs are negatively charged unbranched polysaccharides that consist of repeating disaccharides with various sulfation groups; they provide binding sites for cytokines and growth factors in regulating various cellular processes. In mice, GAG deficiency in dental epithelium leads to the reinitiation of tooth germ development and the formation of supernumerary incisors. Furthermore, GAGs are critical for the differentiation of dental stem cells. Inhibition of GAGs assembly hinders the differentiation of ameloblasts and odontoblasts. In summary, core proteins and GAGs are expressed distinctly and exert different functions at various stages of odontogenesis. Given their unique contributions in odontogenesis, this review summarizes the roles of proteoglycans and GAGs throughout the process of odontogenesis to provide a comprehensive understanding of tooth development.

PRX1-positive mesenchymal stem cells drive molar morphogenesis.

Mammalian teeth, developing inseparable from epithelial-mesenchymal interaction, come in many shapes and the key factors governing tooth morphology deserve to be answered. By merging single-cell RNA sequencing analysis with lineage tracing models, we have unearthed a captivating correlation between the contrasting morphology of mouse molars and the specific presence of PRX1+ cells within M1. These PRX1+ cells assume a profound responsibility in shaping tooth morphology through a remarkable divergence in dental mesenchymal cell proliferation. Deeper into the mechanisms, we have discovered that Wnt5a, bestowed by mesenchymal PRX1+ cells, stimulates mesenchymal cell proliferation while orchestrating molar morphogenesis through WNT signaling pathway. The loss of Wnt5a exhibits a defect phenotype similar to that of siPrx1. Exogenous addition of WNT5A can successfully reverse the inhibited cell proliferation and consequent deviant appearance exhibited in Prx1-deficient tooth germs. These findings bestow compelling evidence of PRX1-positive mesenchymal cells to be potential target in regulating tooth morphology.

[Etiology and clinical treatment strategies for second primary molars without permanent tooth germs].

Congenital tooth agenesis is a type of craniofacial developmental anomaly with reduced number of teeth, which is caused by disturbances in tooth germ development. If the number of missing teeth is less than six (excluding the third molars), it is termed as hypodontia. The second premolars are most commonly affected. When the second premolars are missing, the second primary molars are more prone to suffer from retention, infraocclusion, caries, pulpitis, or periapical periodontitis. Without timely prevention and appropriate treatment, congenital loss of second premolars may cause adverse effects on the patients' tooth arrangement, occlusal function, craniofacial development, and even future prosthetic treatment. This review summarises the aetiological and diagnostic features of the agenesis of second premolars, and discusses the clinical considerations of retaining or extracting the second primary molars without permanent tooth germs, when the absence of permanent tooth germs is fully established or not, so as to provide references for dentists.

Spatiotemporal expression profiles of c-Mpl mRNA in the tooth germ: Comparative expression dynamics of vascularization-related genes.

BACKGROUND: Vascularization is an essential event for both embryonic organ development and tissue repair in adults. During mouse tooth development, endothelial cells migrate into dental papilla during the cap stage, and form blood vessels through angiogenesis. Megakaryocytes and/or platelets, as other hematopoietic cells, express angiogenic molecules and can promote angiogenesis in adult tissues. However, it remains unknown which cells are responsible for attracting and leading blood vessels through the dental papilla during tooth development. METHODS: Here we analyzed the spatiotemporal expression of c-Mpl mRNA in developing molar teeth of fetal mice. Expression patterns were then compared with those of several markers of hematopoietic cells as well as of angiogenic elements including CD41, erythropoietin receptor, CD34, angiopoietin-1 (Ang-1), Tie-2, and vascular endothelial growth factor receptor2 (VEGFR2) through in situ hybridization or immunohistochemistry. RESULTS: Cells expressing c-Mpl mRNA was found in several parts of the developing tooth germ, including the peridental mesenchyme, dental papilla, enamel organ, and dental lamina. This expression occurred in a spatiotemporally controlled fashion. CD41-expressing cells were not detected during tooth development. The spatiotemporal expression pattern of c-Mpl mRNA in the dental papilla was similar to that of Ang-1, which preceded invasion of endothelial cells. Eventually, at the early bell stage, the c-Mpl mRNA signal was detected in morphologically differentiating odontoblasts that accumulated in the periphery of the dental papilla along the inner enamel epithelium layer of the future cusp region. CONCLUSION: During tooth development, several kinds of cells express c-Mpl mRNA in a spatiotemporally controlled fashion, including differentiating odontoblasts. We hypothesize that c-Mpl-expressing cells appearing in the forming dental papilla at the cap stage are odontoblast progenitor cells that migrate to the site of odontoblast differentiation. There they attract vascular endothelial cells into the forming dental papilla and lead cells toward the inner enamel epithelium layer through production of angiogenic molecules (e.g., Ang-1) during migration to the site of differentiation. C-Mpl may regulate apoptosis and/or proliferation of expressing cells in order to execute normal development of the tooth.

Tooth pattern, development, and replacement in the yellow catfish, Pelteobagrus fulvidraco.

Studies of teleost teeth are important for understanding the evolution and mechanisms of tooth development, replacement, and regeneration. Here, we used gross specimens, microcomputed tomography, and histological analysis to characterize tooth structure, development, and resorption patterns in adult Pelteobagrus fulvidraco. The oral and pharyngeal teeth are villiform and conical. Multiple rows of dentition are densely distributed and the tooth germ is derived from the epithelium. P. fulvidraco exhibits a discontinuous and non-permanent dental lamina. Epithelial cells surround the teeth and are separated into distinct tooth units by mesenchymal tissue. Tooth development is completed in the form of independent tooth units. P. fulvidraco does not undergo simultaneous tooth replacement. Based on tooth development and resorption status, five forms of teeth are present in adult P. fulvidraco: developing tooth germs, accompanied by relatively immature tooth germs; mature and well-mineralized tooth accompanied by one tooth germ; teeth that have begun resorption, but not completely fractured; fractured teeth with only residual attachment to the underlying bone; and teeth that are completely resorbed and detached. Seven biological stages of a tooth in P. fulvidraco were also described.

Exploring the role of DNMT1 in dental papilla cell fate specification during mouse tooth germ development through integrated single-cell transcriptomics and bulk RNA sequencing.

OBJECTIVES: This study aimed to investigate the regulatory mechanisms governing dental mesenchymal cell commitment during tooth development, focusing on odontoblast differentiation and the role of epigenetic regulation in this process. METHODS: We performed single-cell RNA sequencing (scRNA-seq) of dental cells from embryonic day 14.5 (E14.5) mice to understand the heterogeneity of developing tooth germ cells. Computational analyses including gene regulatory network (GRN) assessment were conducted. We validated our findings using immunohistochemistry (IHC) and in vitro loss-of-function analyses using the DNA methyltransferase 1 (DNMT1) inhibitor Gsk-3484862 in primary dental mesenchymal cells (DMCs) isolated from E14.5 mouse tooth germs. Bulk RNA-seq of Gsk-3484862-treated DMCs was performed to identify potential downstream targets of DNMT1. RESULTS: scRNA-seq analysis revealed diverse cell populations within the tooth germs, including epithelial, mesenchymal, immune, and muscle cells. Using single-cell regulatory network inference and clustering (SCENIC), we identified Dnmt1 as a key regulator of early odontoblast development. IHC analysis showed the ubiquitous expression of DNMT1 in the dental papilla and epithelium. Bulk RNA-seq of cultured DMCs showed that Gsk-3484862 treatment upregulated odontoblast-related genes, whereas genes associated with cell division and the cell cycle were downregulated. Integrated analysis of bulk RNA-seq data with scRNA-seq SCENIC profiles was used to identify the potential Dnmt1 target genes. CONCLUSIONS: Dnmt1 may negatively affect odontoblast commitment and differentiation during tooth development. These findings contribute to a better understanding of the molecular mechanisms underlying tooth development and future development of hard-tissue regenerative therapies.

Células madre en odontología: nuevas perspectivas / Stem cells in dentistry: new perspectives

En el campo de la odontología, prevalecen actualmente alternativas terapéuticas con una filosofía conservadora. Sin embargo, con el advenimiento de los tratamientos con células madre (CM), se amplían las posibilidades terapéuticas, que buscan la combinación y el equilibrio entre la intervención tradicional y las posibilidades de reposición de estructuras anatómicas dañadas, a través de la regeneración de tejidos utilizando células madre o sus derivados (AU)

In the dentistry field, therapeutic alternatives with a conservative philosophy currently prevail. However, with the advent of stem cell (SC) treatments, therapeutic possibilities are expanding, seeking a combination and balance between traditional intervention and the pos- sibility of replacing damaged anatomical structures through tissue regeneration, using stem cells or their derivatives (AU)

Ep-CAM (MOC-31) expression in tooth germ and ameloblastoma

Background: Ep-CAM, a transmembrane glycoprotein expressed in most epithelium in normal conditions, hasdiverse roles in these tissues, including in cell adhesion, proliferation, differentiation, cell cycle regu-lation, migration and intracellular signaling. It is also over-expressed in most malignant neoplasia, partic-ipating in theinitiation, progression, and metastatic dissemination of the tumor. The expression and roles of this protein in oralneoplasia, particularly in odontogenic tumors, remain unestablished. The objective of this study consisted in analyzing the expression of this protein in ameloblastoma and tooth germ.Material and Methods: Ep-CAM (MOC-31) expression was evaluated by immunohistochemistry in tooth germs(TG) (n = 16) ameloblastomas (AM) (n = 60) and 2 ameloblastic carcinomas. Sections were visualized in theirtotality with an optical microscope, and positivity observed in cell membrane and cytoplasm was graded according to the following semi-quantitative scale: Neg, "essentially unstained", for negative sections or staining <5% ofcells; + for staining of 5-50% of cells; ++ for staining >50% of cells.Results: Most tooth germs expressed MOC-31 (81.3%), strong staining was observed both in the inner epitheliumof the enamel organ and in the adjacent stellate reticulum. 16.7% of the AM cases showed MOC-31 expression,the immunoexpression expression was diffuse at the cytoplasmic and membrane level. The only two cases ofameloblastic carcinoma included were strong positive to MOC-31. No correlation was observed between proteinexpression and gender, age, clinical variants, or histological subtypes.Conclusions: Overexpression was found in TG and ameloblastic carcinoma compared to AM; further studies withdifferent experimental strategies are suggested to clarify the biological significance of this finding. (AU)

Immunohistochemical localization of vascular factors in tooth germ of amphibian (Cynops pyrrhogaster) / Localización inmunohistoquímica de factores vasculares en germen dentario de anfibios (Cynops pyrrhogaster)

SUMMARY: Vascular endothelial growth factor (VEGF) and its receptor, VEGFR-2, are known to regulate blood vessel endothelium growth. They play important role in human and rodents teeth development. In newt jaws, there are sequential developmental teeth germs following behind the mature teeth. We examined the immunohistochemical localization of VEGF and its receptor and showed the specific expression pattern of VEGF and VEGF receptor in Cynops pyrrhogaster sequential tooth development. The intensity of immunoreactivity for VEGF in the inner enamel epithelium was weaker than that in the outer enamel epithelium in the dentine matrix formation and mineralization stages. Finally, at the enameloid maturation and enamel-like matrix formation stage, immunoreactivity for VEGF in inner enamel epithelium was stronger than in the outer enamel epithelium. The intensity of immunoreactivity for VEGFR-2 was positive for the outer enamel epithelium throughout tooth development. The crown sides of the odontoblasts were stained especially strongly for VEGF and VEGFR-2 during the dentine matrix formation and mineralization stage of the enameloid maturation and enamel- like matrix formation stage. We postulate that the expression of VEGF in the inner enamel epithelium and odontoblast widely effects tooth development in newts, as well as in human and rodents.

RESUMEN: Se sabe que el factor de crecimiento endotelial vascular (VEGF) y su receptor, VEGFR-2, regulan el crecimiento del endotelio de los vasos sanguíneos. Desempeñan un papel importante en el desarrollo de los dientes humanos y de los roedores. En las mandíbulas de tritón, hay gérmenes dentales de desarrollo secuenciales que siguen a los dientes maduros. Examinamos la localización inmunohistoquímica de VEGF y su receptor y mostramos el patrón de expresión específico de VEGF y receptor de VEGF en el desarrollo secuencial de dientes de Cynops pyrrhogaster. La intensidad de la inmunorreactividad para VEGF en el epitelio interno del esmalte era más débil que en el epitelio externo del esmalte en las etapas de formación y mineralización de la matriz de dentina. Finalmente, en la etapa de maduración del esmalte y de formación de la matriz similar al esmalte, la inmunorreactividad para VEGF en el epitelio interno del esmalte fue más fuerte que en el epitelio externo del esmalte. La intensidad de la inmunorreactividad para VEGFR- 2 fue positiva para el epitelio externo del esmalte durante el desarrollo del diente. Los márgenes de la corona de los odontoblastos se tiñeron especialmente para VEGF y VEGFR-2 durante la etapa de formación de la matriz de dentina y mineralización de la etapa de maduración del esmalte y la etapa de formación de la matriz similar al esmalte. Postulamos que la expresión de VEGF en el epitelio interno del esmalte y odontoblastos afecta ampliamente el desarrollo de los dientes en tritones, así como en humanos y roedores.

Supernumerary teeth in patients with cleft lip and palate: the tooth germs do not separate

ABSTRACT Introduction: Supernumerary teeth in cases of cleft lip and palate do not result from the division of normal germs before the formation of hard tissue. Deciduous and permanent teeth odontogenesis begins after the face has formed, either with or without the cleft. Discussion: The most acceptable hypothesis to enable understanding of the presence of supernumerary teeth on one or both sides of the cleft palate is hyperactivity of the dental lamina in its walls. This hyperactivity, with the formation of more tooth germs, must be attributed to mediators and genes related to tooth formation, under strong influence of local epigenetic factors, whose developmental environment was affected by the presence of the cleft. Conclusion: The current concepts of embryology no longer support the fusion of embryonic processes for the formation of the face, but rather the leveling of the grooves between them. All human teeth have a dual embryonic origin, as they are composed of ectoderm and mesenchyme/ectomesenchyme, but this does not make it easy for them to be duplicated to form supernumerary teeth.

RESUMO Introdução: Os dentes extranumerários nas fissuras labiopalatinas não são resultado da divisão dos germes normais antes da formação do tecido duro. A odontogênese dos decíduos e permanentes inicia-se depois de formada a face, com ou sem fissuras. Discussão: A hipótese mais plausível para compreender a presença dos dentes extranumerários em um ou nos dois lados da fissura labiopalatina é a hiperatividade da lâmina dentária em suas paredes. Essa hiperatividade, com formação de mais germes dentários, deve ser atribuída aos mediadores e genes relacionados à formação dos dentes, sob forte influência de fatores epigenéticos locais, cujo ambiente de desenvolvimento foi afetado pela presença da fissura. Conclusão: Os conceitos atuais da embriologia não fundamentam mais a fusão de processos embrionários para a formação da face, e sim o nivelamento dos sulcos entre eles. Todos os dentes humanos têm uma dupla origem embrionária, pois se compõem de ectoderma e mesênquima/ectomesênquima, mas isso não facilita sua duplicação para formar dentes extranumerários.

Odontoma e retenção dentária: relato de caso / Odontoma and dental retention: case report

Este relato de caso teve como objetivo descrever a realização de um procedimento cirúrgico de remoção de um odontoma composto em um paciente pediátrico, e a partir disto elucidar a importância do diagnóstico precoce, assim como o seu tratamento. Um paciente do sexo masculino de 8 anos com ausência de erupção dos germes dentários 21 e 22 e retenção prolongada dos dentes 61 e 62. Foi realizado o planejamento cirúrgico de remoção do tumor e dos elementos dentários não esfoliados. Durante o acompanhamento de 6 meses do paciente houve a erupção do dente 22 e o 21 permaneceu retido, o qual se encontra em acompanhamento ortodôntico para manutenção do espaço e possível tracionamento orto-cirúrgico. Portanto, o diagnóstico e investigação de situações clínicas e radiográficas sugestivas de odontomas são imprescindíveis para evitar danos futuros a dentição permanente... (AU)

This case report aimed to describe the performance of a surgical procedure of removal of a compound odontoma in a pediatric patient, and from this to elucidate the importance of early diagnosis and treat ment. A male patient 8 years old without no eruption of tooth germs 21 and 22 and prolonged retention of teeth 61 and 62. Surgical planning was carried out to remove the tumor and the unexfoliated teeth. During the 6-month follow-up of the patient, the eruption of tooth 22 and 21 remained retained, which is under orthodontic follow-up to space maintenance and possible ortho-surgical traction. Therefore, the diagnosis and investigation of clinical and radiographic situations suggestive of odontomas are essential for prevent future damage to permanent teeth.removal of a compound odontoma in a pediatric patient, and from this to elucidate the importance of early diagnosis and treatment. A male patient 8 years old without no eruption of tooth germs 21 and 22 and prolonged retention of teeth 61 and 62. Surgical planning was carried out to remove the tumor and the unexfoliated teeth. During the 6-month follow-up of the patient, the eruption of tooth 22 and 21 remained retained, which is under orthodon tic follow-up to space maintenance and possible ortho-surgical traction. Therefore, the diagnosis and investigation of clinical and radiographic situations suggestive of odontomas are essential for prevent future damage to permanent teeth... (AU)

Evaluation of gubernacular tract with cone beam computed tomography in impacted supernumerary teeth

The gubernacular canal or gubernacular tract is filled by the gubernacular cord, which includes fibrous connective tissue containing peripheral nerves, blood and lymphatic ducts besides the epithelial cells from the fragmented dental laminae, including epithelial growth factor. The purpose of this study was to evaluate the gubernacular tract in unerupted supernumerary teeth by cone beam computed tomography. Sixty-four unerupted supernumerary teeth were selected from 44 patients (21 females, 23 males, 12-68 years). Gubernacular tract characteristics were evaluated in five different groups: No alteration, bending of gubernacular tract, contraction of gubernacular tract, obliterations of gubernacular tract, difference between erupted direction. Unerupted supernumerary teeth were classified according to their position. The presence and characteristics of the gubernacular tract in the supernumerary teeth were evaluated by cone beam computed tomography. In our study, the frequency of the gubernacular tract was found to be 31.7%. There was no significant difference between the presence of gubernacular tract and gender, age and gubernacular tract characteristics. It was found that gubernacular tract characteristics did not change according to gender, quadrant, age and unerupted positions. Cone beam computed tomography is an efficient method for the evaluation of the gubernacular tract in unerupted supernumerary teeth. Conducting these studies in larger populations will provide more detailed information about the prognosis of impacted supernumerary teeth

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Effect of a novel bioceramic root canal sealer on the angiogenesis-enhancing potential of assorted human odontogenic stem cells compared with principal tricalcium silicate-based cements

Abstract Objective: This study evaluated the angiogenesis-enhancing potential of a tricalcium silicate-based mineral trioxide aggregate (ProRoot MTA), Biodentine, and a novel bioceramic root canal sealer (Well-Root ST) in human dental pulp stem cells (hDPSCs), human periodontal ligament stem cells (hPLSCs), and human tooth germ stem cells (hTGSCs). Methodology: Dulbecco's modified Eagle's medium was conditioned for 24 h by exposure to ProRoot MTA, Biodentine, or Well-Root ST specimens (prepared according to the manufacturers' instructions). The cells were cultured in these conditioned media and their viability was assessed with 3-(4,5-dimethyl-thiazol-2-yl)-5-(3-carboxy-methoxy-phenyl)-2-(4-sulfo-phenyl)-2H tetrazolium (MTS) on days 1, 3, 7, 10, and 14. Angiogenic growth factors [platelet-derived growth factor (PDGF), basic fibroblast growth factor (FGF-2), and vascular endothelial growth factor (VEGF)] were assayed by sandwich enzyme-linked immunosorbent assay (ELISA) on days 1, 7, and 14. Human umbilical vein endothelial cell (HUVEC) migration assays were used to evaluate the vascular effects of the tested materials at 6-8 h. Statistical analyses included Kruskal-Wallis, Mann-Whitney U, and Friedman and Wilcoxon signed rank tests. Results: None of tricalcium silicate-based materials were cytotoxic and all induced a similar release of angiogenic growth factors (PDGF, FGF-2, and VEGF) (p>0.05). The best cell viability was observed for hDPSCs (p<0.05) with all tricalcium silicate-based materials at day 14. Tube formation by HUVECs showed a significant increase with all tested materials (p<0.05). Conclusion: The tricalcium silicate-based materials showed potential for angiogenic stimulation of all stem cell types and significantly enhanced tube formation by HUVECs.

¿Cuál es su diagnóstico? / What is your diagnosis?

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Estudio de la proliferación celular en gérmenes dentarios humanos / Cell proliferation study in human tooth germs

El objetivo de este estudio fue conocer la expresión de MCM4-5-6 en gérmenes dentarios humanos en estado de campana. Materiales y Métodos Se obtuvieron preparados histológicos de 4 maxilares fetales incluidos en parafina en el archivo de bloques de la cátedra de Histología de la Facultad de Odontología, UdelaR. Se procedió al corte de los mismos en secciones para técnica de rutina (HE) y de IHQ para MCM 4, 5 y 6. Resultados: Las diferentes regiones del órgano del esmalte mostraron 100 % de positividad en el estrato intermedio, una variación de 100 % a 0 % en el epitelio interno del órgano del esmalte, desde el sector cervical al sector incisal del mismo, y0% tanto en el retículo estrellado como en el epitelio externo del órgano del esmalte. Conclusiones: Los resultados obtenidos permitieron evidenciar y confirmar la acción proliferativa de las diferentes zonas del órgano del esmalte.

The aim of this study was to determine the expression of MCM4-5-6 in human tooth germs in the bell stage. Materials and methods: Histological samples were collected from four fetal maxillae placed in paraffin at the block archive of the Histology Department of the School of Dentistry, UdelaR. Sections were made for HE routine technique and for immunohistochemistry technique for MCM4-5-6. Results: Different regions of the enamel organ showed 100% positivity in the intermediate layer, a variation from 100% to 0% in the inner epithelium from the cervical loop to the incisal area, and 0% in the stellar reticulum as well as the outer epithelium. Conclusions: The results show and confirm the proliferative action of the different areas of the enamel organ.

Aspectos radiográficos de imágenes periapicales asociadas a incisivos primarios traumatizados / Aspectos radiográficos de imagens periapicais associadas a incisivos decíduos traumatizados / Radiographic aspects of periapical images associated with traumatized primary incisors

Las imágenes radiolúcidas periapicales que involucran dientes primarios traumatizados se pueden confundir entre sí y dar lugar a diagnósticos erróneos y tratamiento. Por lo tanto, es importante identi-ficar las características radiográficas de las imágenes radiolúcidas periapicales en los incisivos prima-rios traumatizados, principalmente debido al hecho de que la superposición de imágenes se produce en esta región. Además, es frecuente observar la expansión del folículo haciendo que el diagnóstico radiográfico sea aún más difícil. El objetivo de este estudio fue describir, a través de una revisión de la literatura, las características radiográficas de las imágenes periapicales asociadas con los incisivos primarios traumatizados.

Periapical radiolucencies involving traumatized primary teeth can be confused with each other and lead to misdiagnosis and treatment. Therefore, it is important to identify radiographic characteristics of periapical radiolucent images in traumatized primary incisors, mainly due to the fact that overla-pping of images occurs in this region. Besides, it is frequent to observe follicle expansion making the radiographic diagnosis even more difficult. The objective of this study was to describe, through a literature review, the radiographic characteristics of periapical images associated with traumatized primary incisors.

As radioluscências periapicais envolvendo dentes decíduos traumatizados podem ser confundidas entre si e levar a um erro de diagnóstico e tratamento. Por isso, é importante identificar características radiográficas de imagens radiolúcidas periapicais em incisivos decíduos traumatizados, principalmente pelo fato que nesta região ocorre sobreposição de imagens e, é frequente observar expansão do folículo, dificultando ainda mais o diagnóstico radiográfico. O objetivo deste trabalho foi descrever através de uma revisão de literatura as características radiográficas de imagens periapicais associadas a incisivos decíduos traumatizados.

Expression of hMLH1 and hMSH2 proteins in ameloblastomas and tooth germs

Background: Mismatch repair proteins (MMRPs) are a group of nuclear enzymes that participate in the repair of base mismatches that occur during DNA replication in all proliferating cells. The most studied MMRPs are hMSH2 and hMLH1, which are known to be highly expressed in normal tissues. A loss of MMRPs leads to the accumulation of DNA replication errors in proliferating cells. Ki-67 is a biomarker regarded to be the gold-standard tool for determining cell proliferation by immunohistochemical methods. The aim of this study was to investigate the immunohistochemical expression of hMLH1, hMSH2 and Ki-67 proteins in ameloblastomas and tooth germs, to contribute to the understanding of the development of this odontogenic neoplasm. Material and Methods: Immunohistochemical assays to determine the presence of proteins hMSH2, hMLH1 and Ki-67 were performed in 80 ameloblastomas (40 solid and 40 unicystic) and five tooth germs. Results: Unicystic ameloblastomas showed higher MMRP expression (hMLH1: 62.5 ± 43.4; hMSH2: 83.3 ± 47.8) than did solid ameloblastomas (hMLH1: 59.4 ± 13.5; hMSH2: 75.8 ± 40.2). Additionally, the cell proliferation index assessed by Ki-67 was inversely proportional to the expression of MMRP. Comparison between tooth germs and ameloblastoma revealed significantly higher expression of hMLH1, hMSH2 and Ki-67 in tooth germs (p=0.02). Conclusions: The differences of MMRP and Ki-67 immunoexpression between ameloblastomas and tooth germ suggest that alterations in the MMRP mechanisms could participate in the biological behavior of ameloblastomas (AU)

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Predicción del tercer molar e indicaciones de germenectomía: reporte de un caso / Prediction of the third molar and indications of germectomy: report of a case

Los factores ambientales y evolutivos, los cambios en los hábitos dietéticos, entre otros, pueden desencadenar un papel etiológico en la aparición de anomalías dentales llevando a la especie humana a una disminución en la función masticatoria que trae como consecuencia una reducción en el tamaño de los maxilares originando la falta de espacio para la correcta posición de los dientes en el arco dental, lo que provoca un aumento en la incidencia de casos de segundos y terceros molares retenidos con su consecuente patología multisintomática ocasionando de esta manera un problema de salud pública. Diversos autores han utilizado las imágenes radiográficas para realizar análisis específicamente del tercer molar, basándose en una proyección lateral y panorámica para, mediante marcas y referencias, establecer un diagnóstico y determinar el riesgo y la necesidad de su extracción. La imagenología presenta una nueva herramienta que es la tomografía Cone Beam que nos permite adaptar los conocimientos clásicos del análisis del tercer molar a una imagen en tres dimensiones, aportando el factor profundidad (AU)

Environmental factors, evolutionary changes in dietary habits, among others can trigger an etiological role in the appearance of dental anomalies. Taking the human species to a decrease in masticatory function resulting in a reduction in the size of the jaws, resulting in a lack of space for the correct position of the teeth in the dental arch. Causing an increase in the incidence of second and third molars retained. Its eruption restriction consequent multisymptomatic pathology causing a public health problem in this way. Several authors have used the radiographic images to perform analyzes of the third molar. Based on a lateral and a panoramic radiographic projection, to establish a diagnosis and determine the risk and the need to extract it. Imaging diagnostic presents a new tool that is Cone Beam tomography that allows us to adapt the classical knowledge of the third molar analysis to an image in three dimensions, providing the depth factor (AU)

Remoção de terceiro molar superior deslocado para o espaço bucal / Removal of upper third molar displaced to the buccal space

Os autores descrevem um caso clínico de deslocamento de germe dentário de terceiro molar superior esquerdo para o espaço bucal em um paciente de 13 anos de idade. A localização do dente em posição profunda com envolvimento do corpo adiposo do bucinador dificultou a sua localização, ainda não descrita, nas condições em questão, na literatura. Com a Tomografia Computadorizada de Feixe Cônico (TCFC), foi possível localizar o dente deslocado e planejar a sua remoção. Os riscos e benefícios das extrações de germes de terceiros molares precisam ser avaliados devido ao grande risco de deslocamentos... (AU)

The authors describe a case of displacement of left upper third molar tooth germ to the buccal space in a patient 13 years old. The deep position of the tooth with involvement of the fat body of the buccinator made it difficult its location, still not described, under the concerned conditions, in the literature. With the cone beam computed tomography (CBCT), it was possible determine the location of the tooth and plan his removal. The risks and benefits of third molar tooth germ extraction should be evaluated because there is a greater chance of displacement... (AU)