Connexin 43 expression in tooth germ and benign odontogenic tumors.

OBJECTIVE: The aim of this study was to investigate and compare the immunohistochemical expression of connexin 43 (Cx43) in tooth germs (TGs), ameloblastic fibromas (AFs), ameloblastic fibro-odontomas (AFOs), and conventional ameloblastomas (AMs). STUDY DESIGN: Nine TGs, 12 AFs, 12 AFOs, and 27 AMs were evaluated for Cx43 expression by immunohistochemistry. RESULTS: Most of the TGs expressed Cx43 in the mesenchyme (77.6%) and in the late stages of odontogenesis. Cx43 was more highly expressed (P < .05) in the mesenchymal layer of all groups than in the epithelial layer except for the AFOs. When comparing the expression of Cx43 in the different layers of the analyzed groups, statistically significant differences were observed between AFO vs AM (*P = .0158) in the epithelial layer and between AF vs AFO (P** = .0046) in the mesenchymal layer. CONCLUSIONS: The results obtained in this study showed that Cx43 is a protein with important expression in the mesenchymal layer of the embryonic and odontogenic tissues studied. It could be speculated that Cx43 participates in mineralization events based on the relationship of the expression of this protein between the epithelial and mesenchymal layers of odontogenic tissues.

Spatial distribution of CD34 protein in primordial odontogenic tumour, ameloblastic fibroma and the tooth germ.

BACKGROUND: Primordial odontogenic tumour is a benign mixed neoplasm of recent description, which has histological similarities with other odontogenic tumours such as the ameloblastic fibroma. In this article, we investigate the architecture of the sub-epithelial layer of mesenchymal cells expressing the marker CD34 in primordial odontogenic tumour. OBJECTIVE: Analyse the spatial patterns of CD34 expression in primordial odontogenic tumour and compare them with those in ameloblastic fibroma and the normal tooth germ by means of objective imaging approaches, to better characterise these lesions. METHODS: Two cases of primordial odontogenic tumour, four cases of ameloblastic fibroma and two cases of tooth germ in cap and bell stages were used for morphological, structural and immunohistochemical analyses. RESULTS: CD34 expression was found in vascular endothelium of primordial odontogenic tumour, ameloblastic fibroma and tooth germ. In addition, a characteristic sub-epithelial expression was observed only in primordial odontogenic tumour, corresponding to 84%-86% of the sample boundaries. Moreover, the zone expressing CD34 corresponded with a higher cellularity, which was absent in ameloblastic fibroma and tooth germ. CONCLUSION: Image analysis of the primordial odontogenic tumour architecture revealed characteristics absent in other odontogenic tumours and tooth germs. This study provides additional information to support the idea that this neoplasm is a distinct entity from early stage AF or developing odontoma.

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

BACKGROUND: Ep-CAM, a transmembrane glycoprotein expressed in most epithelium in normal conditions, has diverse roles in these tissues, including in cell adhesion, proliferation, differentiation, cell cycle regulation, migration and intracellular signaling. It is also over-expressed in most malignant neoplasia, participating in the initiation, progression, and metastatic dissemination of the tumor. The expression and roles of this protein in oral neoplasia, 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 their totality 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% of cells; + 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 epithelium of 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 of ameloblastic carcinoma included were strong positive to MOC-31. No correlation was observed between protein expression and gender, age, clinical variants, or histological subtypes. CONCLUSIONS: Overexpression was found in TG and ameloblastic carcinoma compared to AM; further studies with different experimental strategies are suggested to clarify the biological significance of this finding.

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)

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

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.

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)

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.

Perilipin 1 and adipophilin immunoexpression suggests the presence of lipid droplets in tooth germ, ameloblastoma, and ameloblastic carcinoma.

BACKGROUND: Increased lipogenesis and lipid droplet accumulation are observed in diverse tumors, and these processes are associated with poor prognosis in several tumors, representing potential therapeutic targets. The presence of lipid droplets in odontogenic tissues and/or tumors is unknown. METHODS: Immunohistochemistry for perilipin 1 and adipophilin was performed in 12 human tooth germs (TG), 27 conventional ameloblastoma (AM), and 8 ameloblastic carcinoma (AC) samples. Cytoplasmic staining was analyzed using an immunoreactive score (IRS), and the results were compared for the TG, AM, and AC samples by Kruskal-Wallis test followed by Dunn's post-test and confirmed by Mann-Whitney U test. RESULTS: Perilipin 1 was negative in 91.7% of the TG samples, positive in 48.2% of the AM samples, and positive in 87.5% of the AC samples. Adipophilin was positive in 100% of the TG samples, 92.6% of the AM samples, and 100% of the AC samples. The perilipin 1 and adipophilin IRS revealed statistically significant differences between the TG, AM, and AC samples (p = .007 and p = .018, respectively). The perilipin 1 levels among the TG and AC samples were statically significant (**p = .0085), as well as the adipophilin levels when TG and AM samples were compared (**p < .0029). CONCLUSIONS: Adipophilin exhibits significant activity in human tooth development. The immunoexpression of perilipin 1 and adipophilin in the AM and AC samples suggests the presence of lipid droplets, providing further evidence of metabolic alterations in these tumors. Additional studies with larger samples and alternative techniques are necessary to confirm these findings.

Methylphenidate effects on mice odontogenesis and connections with human odontogenesis.

The purpose of this study is to evaluate the effects of Methylphenidate exposure on mice odontogenesis and connect them by bioinformatics with human odontogenesis. Thirty-two pregnant Swiss mice were divided into treated group and control group, which received, respectively, 5 mg/kg of Methylphenidate and saline solution from the 5th to the 17th day of pregnancy. The mouse embryos tooth germs were analyzed through optical microscopy, and the data collected were analyzed statistically by Fisher's exact test. The presence and similarity of Methylphenidate-associated genes (Pharmgkb database) in both organisms and their interaction with dental development genes (AmiGO2 database) were verified on STRING database. Rates of tooth germ malformations were higher in treated than in control group (Control: 18; Treated: 27; p = 0.035). Mouse embryo malformations were connected with 238 interactions between 69 dental development genes with 35 Methylphenidate genes. Fourteen interactions for four Methylphenidate genes with four dental development genes, with human experimental data, were connected with mouse phenotype data. By homology, the interactions and conservation of proteins/genes may indicate similar outcomes for both organisms. The exposure to Methylphenidate during pregnancy affected odontogenesis in mouse embryos and may affect human odontogenesis. The study of malformations in mice, with a bioinformatics approach, could contribute to understanding of the Methylphenidate effect on embryo development. These results may provide novel hypotheses for further testing and reinforce the FDA protocol: as Methylphenidate is included in category C, its use during pregnancy should be considered if the benefits outweigh the risks.

Expression of caveolin-1 in tooth germ, ameloblastoma and ameloblastic carcinoma.

BACKGROUND: The caveolin-1 protein (structural component of membrane caveolae) plays important roles in several biological functions, such as endocytosis, cell adhesion, and cell signaling. However, this protein has been associated with mechanisms of tumorigenesis in several neoplasms. The expression patterns and roles of caveolin-1 in the oral epithelium and in embryonic and odontogenic tumor tissues are still unclear. MATERIAL AND METHODS: The expression of caveolin-1 was evaluated in samples of the normal gingival epithelium (n=7), human tooth germ (TG) (n=12), ameloblastoma (AM) (n=83), and ameloblastic carcinoma (AC) (n=9) by immunohistochemistry. Additionally, AM samples were analyzed by qRT-PCR and Western blot. RESULTS: Most TG (91.7%), AM (73.5%) and AC (100%) samples showed diverse patterns of immunohistochemical positivity for caveolin-1, while only one gingival sample was positive. The transcript levels of cav-1 were significantly upregulated by 14.9-fold in AM tissue (P = 0.0014) compared to those in normal gingival epithelial tissue, as shown by qRT-PCR. Presence of caveolin-1 protein was confirmed by Western blot analysis. The caveolin-1 immunoexpression patterns throughout the stages of TG show its importance during odontogenesis. CONCLUSIONS: The overexpression of caveolin-1 in AM and AC compared to its expression in normal gingival epithelium (adult tissue) suggests a possible role of caveolin-1 in protumoral events, but due to the similar immunoexpression observed in AM and AC, caveolin-1 may not necessarily participate in the malignant transformation process. However, future studies are needed to clarify and confirm these hypotheses.

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.

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.

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.

Prognóstico entre eixo de erupção dos caninos permanentes superiores e espaço para erupção dos segundos molares inferiores / Prognosis between superior permanent canines teeth eruption axis and second lower molars space for eruption

Resumo O objetivo deste estudo foi verificar a associação entre a má posição do germe dos segundos molares inferiores com o eixo de erupção dos caninos permanentes superiores na dentadura mista. A amostra foi composta por 506 radiografias panorâmicas digitais, no período intertransitório da fase de dentadura mista, na faixa etária de 7 a 12 anos, de ambos os sexos. Os caninos foram avaliados utilizando-se a divisão da porção anterior do hemiarco em cinco setores sendo o setor 1 a melhor posição para eixo de erupção correto e 5 para a pior. Para a localização do germe dos segundos molares inferiores foi utilizada a distância horizontal entre a face distal dos primeiros molares inferiores e a borda anterior do ramo da mandíbula. Os dados foram analisados por tabelas de distribuição de frequências e regressão logística, com estimação dos Odds Ratio brutos e os respectivos intervalos de confiança. Não houve associação significativa entre o sexo e o eixo de erupção de caninos permanentes superiores (p>0,05). Houve associação entre a má posição de segundos molares inferiores e o eixo de erupção de caninos. Participantes com má posição de segundos molares inferiores apresentaram 3,40 (IC 95%, 2,12-5,47) vezes mais chance de ter o eixo de erupção de caninos permanentes superiores mal posicionados. Conclui-se que houve associação entre a má posição de segundos molares inferiores e o eixo de erupção de caninos.(AU)

Abstract This study aimed to associate malposition of lower second molar germ with the upper permanent canine teeth eruption axis in the mixed dentition. The sample included 506 digital panoramic radiographies taken in the mixed dentition inter-transitional period in the age group of 7 to 10 years of both sexes. The canines were assessed by dividing the anterior portion of the hemiarch into five sectors, in which sector 1 was the best position for the correct eruption axis and 5 was the worst. For locating the lower second molar germ, a horizontal distance was used between the distal aspect of the lower first molars and the anterior margin of the mandibular ramus. The data was analyzed with frequency distribution and logistic regression tables, estimating crude Odds Ratio and respective confidence intervals. There was no significant association between sex and upper permanent canines eruption axis (p>0.05). There was association between the lower second molars malposition and canines eruption axis. Participants with malposition of lower second molars presented 3.40 (95% CI, 2.12-5.47) times more likely to present upper permanent canines eruption axis malpositioned. It was concluded that there was association between the malposition of lower second molars and the canine eruption axis. (AU)

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.

Dental trauma on primary teeth at different root resorption stages-A dynamic finite element impact analysis of the effect on the permanent tooth germ.

BACKGROUND/AIM: Dental trauma is a common emergency in children with primary teeth. The aim of this study was to determine stress propagation to the permanent tooth germ and surrounding bone and soft tissues during dental trauma to primary central incisors with three levels of physiological root resorption. MATERIAL AND METHODS: Stresses were determined using finite element analysis (FEA). Cross-sectional models were created using cone-beam computed tomography images of 3.5, 5, and 6 years olds, representing three different physiological root resorption stages of a maxillary primary central incisor. The models included periodontal ligament, bone, and soft tissues. An impact with an asphalt block moving at 1 m/s,was simulated for two impact two directions, frontal on the labial tooth surface, and on the incisal edge. Stresses and strains were recorded during impact. RESULTS: The impact caused stress concentrations in the surrounding bone and soft tissues and permanent tooth germ, regardless of the direction of impact and the primary tooth resorption stage. Impact stresses in dental follicles and surrounding bone increased in models with more physiological root resorption of the primary tooth. Incisal impact generated higher stress concentrations in surrounding bone and soft tissues and permanent tooth germ regardless of physiological root resorption stage. The primary incisor with no physiological root resorption showed high stress concentrations at its root apex. CONCLUSION: During impact to a primary incisor, stresses most significant for potential damage to the formation of permanent enamel and dentin were at the dental follicle and surrounding bone tissue with the three levels of physiological root resorption.

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.

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)

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.