Quistes Dentígeros Asociados a Sacos Foliculares Patológicos de Terceros Molares Incluidos

Establecer la frecuencia y características de quistes dentígeros asociados a sacos foliculares de terceros molares incluidos, extraídos en las clínicas de cirugía oral de la Facultad de Odontología de la Universidad Nacional de Colombia. Estudio cuantitativo, se realizó el análisis histopatológico de 30 sacos foliculares de terceros molares incluidos con col oración de hematoxilina-eosina. Se analizaron 30 biopsias de sacos foliculares de terceros molares superiores e inferiores correspondientes a 21 pacientes con edades comprendidas entre los 17 a 36 años (media: 25,3). De los sacos estudiados 25 (83,3 %) se diagnosticaron como quiste dentígero y 5 (16,7 %) como saco folicular, siendo más frecuente el diagnóstico de quiste dentígero en la zona mandibular. El saco folicular asociado al tercer molar incluido tiene alta capacidad de desarrollar patolo gía odontogénica quística, siendo la más frecuente el quiste dentígero con predilección a la ubicación anatómica en la mandíbula.

To establish the frequency and characteristics of dentigerous cysts associated with follicular sacs of impacted third molars extracted in the oral surgery clinics at the School of Dentistry at Universidad Nacional de Colombia. Quantitative study, a histopathological analysis of 30 follicular sacs of impacted third molars with hematoxylin-eosin staining was performed. 30 biopsies of follicular sacs of upper and lower third molars corresponding to 21 patients aged between 17 and 36 years (mean: 25.3) were analyzed. Of the sacs studied 25 (83.3%) were diagnosed as dentigerous cysts and 5 (16.7%) as follicular sacs, with the diagnosis of dentigerous cysts being more frequent in the mandibular area. The follicular sac associated with impacted third molars has a high capacity to develop cystic odontogenic pathology, being the most frequent the dentigerous cyst with a predilection for the anatomical location in the mandible.

Avaliação das alterações moleculares dos folículos dentários em relação à idade cronológica / Evaluation of molecular changes in dental follicles in relation to chronological age

O Folículo dental (FD) é um tecido de origem ectomesenquimal. Aproximadamente 57% dos adultos apresentam terceiro molar mandibular impactado, sendo esse elemento dentário com maior prevalência de impactação dental. Há maior incidência de alterações patológicas em indivíduos mais velhos em comparação com indivíduos mais jovens. Porém os mecanismos envolvidos na formação de cistos e tumores relacionados aos FDs não estão bem elucidados, e, por isso, alguns autores defendem a extração profilática dos terceiros molares inclusos. Durante o envelhecimento cronológico, padrões epigenéticos mudam, e um padrão de hipometilação global do DNA pode ser encontrado concomitantemente com hipermetilação de vários genes supressores tumorais. A metilação do DNA é um dos mecanismos que regula as vias de sinalização celular, como a da MAPK/ERK, que atuam no controle da proliferação e diferenciação. Alguns pesquisadores descobriram um aumento na atividade do ERK 1/2 durante o processo de envelhecimento, o que poderia contribuir para a ocorrência de doenças, e a sua desregulação está envolvida na indução e na progressão de doenças como câncer e doenças autoimunes. Portanto, o presente estudo teve por objetivo avaliar se os FDs de indivíduos jovens e indivíduos mais velhos apresentam diferença no perfil de metilação global do DNA, e avaliar o padrão de imunoexpressão da forma fosforilada ERK1/2 (pERK1/2) nos FDs. A metilação global do DNA (percentual de 5mC) e a hidroximetilação (5hmC) foram avaliadas por ELISA em 59 amostras. Testamos a correlação entre o conteúdo de 5mC e 5hmC e a correlação de cada um com a idade dos pacientes. Examinamos a imunorreatividade do pERK 1/2 para avaliar a ativação das vias MAPK/ERK em 46 amostras de FD. As amostras apresentaram variação entre 13 e 31 anos de idade. Os resultados mostraram uma relação inversamente proporcional entre o conteúdo de 5hmC e idade até os 19 anos, portanto o percentual de 5hmC nos FDs tende a diminuir linearmente com o envelhecimento. O estudo imuno-histoquímico mostrou um padrão variável de imunoexpressão de pERK1/2 com 46% (21/46) das amostras exibindo menos de 10% de células positivas, enquanto 24% (11/46) das amostrasapresentaram imunopositividade entre 10 e 50% e 30% (14/46) das amostras mais de 50% das células de FD. Não foi observado diferença nas idades entre esses grupos. Em conclusão, nossos resultados sugerem que a hidroximetilação global do DNA possui alteração no seu padrão durante o envelhecimento e que a via de sinalização celular MAPK/ERK está ativa nos FDs.

The dental follicle (DF) is a tissue of ectomesenquimal origin. Approximately 57 % of young adults have impacted third molars, which is the most prevalent impacted tooth. The incidence of pathological changes is greater among older individuals than younger individuals. However, the mechanisms behind the formation of cysts and tumors related to DFs have not been fully clarified and, therefore, some researchers defend the prophylactic extraction of third molars. During chronological aging, epigenetic patterns change and a global DNA hypomethylation pattern can be found concomitantly with hypermethylation of several tumor suppressor genes. DNA methylation is one of the regulators of cell signaling pathways, such as the MAPK/ERK pathway. Some researchers have found an increase in ERK1/2 activity during the aging process, which may contribute to the occurrence of disease, and its dysregulation is involved in the induction and progression of diseases such as cancer and autoimmune diseases. Thus, the aim of the present study was to evaluate whether DFs in young and older individuals differ in terms of global methylation and hydroxymethylation and to evaluate the immunoexpression pattern of phosphorylated ERK1/2. Global DNA methylation (5mC content) and hydroxymethylation (5hmC) were evaluated by ELISA in 59 DF samples We tested the correlation between 5mC and 5hmC content, and the correlation of each with patients' age. We examined ERK1/2 immunoreactivity for the evaluation of the activation of the MAPK pathways in 46 DF samples. Age of patients of the 59 samples of DFs raged from 13 to 31 years. An inversely proportional relation was found between the 5hmC content and age up to 19 years, therefore, the percentage of 5hmC in the DFs tends linearly decrease with aging. The immunohistochemical study showed a variable pattern of immunoexpression of pERK 1/2 with 46% (21/46) of the samples showing less than 10% of positive cells, while 24% (11/46) of the samples showed immunopositivity between 10 and 50% and 30% (14/46) of the samples greater than 50% of the DF cells. There was no difference in age among these groups. In conclusion, our results suggest that the global hydroxymethylation of DNA changes in its pattern during aging and that the MAPK/ERK cell signaling pathway is active in DFs.

miR-214 inhibits the osteogenic differentiation of dental follicle cells in vitro / 口腔疾病防治

Objective @# To investigate the effect of miR-214 on the osteogenic differentiation of dental follicle cells (DFCs).@*Methods@#Purified DFCs were cultured in vitro by bidirectional differential passage, with the untransfected DFCs as the control group (DFCs group). The expression of miR-214-3p in DFCs was upregulated and downregulated by transfection of miR-214-3p(miR-214 mimics group) or miR-214-3p inhibitors(miR-214 inhibitor group) into DFCs. The expression levels of miR-214, alkaline phosphatase (ALP), osteonectin (OSN) and runt-related transcription factor-2(RUNX-2) were detected by qRT-PCR after 7 days of osteogenesis induction, the protein expression levels of RUNX-2 and β-catenin were detected by western blot, and the formation of mineralized nodules was observed with alizarin red staining after 14 days of osteogenesis induction. @*Results @# Compared with the DFCs group, in the miR-214 mimics group, the expression of miR-214 was upregulated after 7 days of osteogenesis induction. The mRNA expression of ALP, OSN and RUNX-2 in the miR-214 mimics group was lower than that in the DFCs group, but only ALP in the two groups was statistically significant (P > 0.05); the mRNA expression of ALP, OSN and RUNX-2 in the miR-214 inhibitor group was higher than that in the DFCs group, and the difference was statistically significant (P < 0.05). The protein expression of RUNX-2 and β-catenin in the miR-214 mimics group was lower than that in the miR-214 inhibitor group. The number of calcified nodules in the miR-214 mimics group was significantly less than that in the DFCs group, while that in the miR-214 inhibitor group was significantly higher than that in the DFCs group. @*Conclusion@#The upregulation of miR-214 can downregulate the expression of β-catenin, can inhibit the expression of ALP, OSN and RUNX-2 related to osteogenesis, and can inhibit osteogenic differentiation. The downregulation of miR-214 demonstrated the opposite results; miR-214 may downregulate the expression of β-catenin and inhibit the osteogenic differentiation of DFCs.

Pathological Changes in Radiographically Normal Dental Follicule: A CBCT Study

Introduction: Dental follicle arises from odontogenicmesenchyme which result in tooth formation. Study aimed toestimate pathological alteration in follicle of impacted thirdmolar(ITM) in cone beam computer tomography (CBCT)and correlation with patient’s age, gender, site and angularposition.Material and Methods: Dental follicle (DF) from 80 ITMwere collected from 68 patients with follicular space ≤ 1.5 mmas measured from the CBCT. dental follicle associated withimpacted teeth were extracted and sent for histopatholicalexamination. statistical analysis was performed.Results: In 80 follicles which were evaluated for patholocalchanges were taken from patients ranging from age of 18to 50 years with a mean age of 37.5 years out if which 21were females and 19 were males. Pathological alterationwere found associated with 10 (35%) follicles which wasstatistically significant (p < 0.001). Incidence of pathologywas slightly more in females and in mandibular jaw. Lesionswere most commonly seen in jaws which were distoangularlyand horizontally impacted.Conclusion: it was concluded that radiographically normalappearing impacted teeth may be associated with variouspathology. So histopatholoic evaluation of all impacted teethis mandatory

Explanation for the signs and symptoms of tooth eruption: mast cells

Abstract This study contributes to the understanding of the mechanisms associated with signs and symptoms of tooth eruption, by investigating the presence of mast cells in pericoronal tissues during the intraosseous (Group 1) and submucosal (Group 2) phases of eruption. We compared findings for these two groups with each other and with those for the oral mucosa (Group 3). In each group, 14 specimens were analyzed microscopically after hematoxylin and eosin staining and immunohistochemical analysis of c-Kit and tryptase expression. Results revealed that the number and density of mast cells is different in follicular tissues according to the eruption phase, which may mean that: 1) masticatory trauma of the oral mucosa and dental follicles in the submucosa may explain why reduced enamel epithelium exposes enamel to the cells of the connective tissue; 2) exposure of antigenic enamel proteins might correspond to the release of sequestered antigens, which may lead to the interaction of IgE and a greater number of mast cells in the region; and 3) the consequent degranulation and the local release of mediators, such as histamine, leukotrienes, prostaglandins, proteases, cytokines and growth factors, contribute to the understanding of signs and symptoms associated with tooth eruption.

Resumo Para contribuir com a compreensão dos mecanismos relacionados à sintomatologia e aos sinais associados à erupção dentária, investigou-se a presença de mastócitos nos tecidos pericoronários na fase intraóssea (Grupo 1) e submucosa (Grupo 2), comparando-os entre si e com a mucosa bucal (Grupo 3). Em cada grupo, 14 espécimes foram analisados microscopicamente em cortes corados com hematoxilina e eosina, e imunocitoquimicamente marcados com Ckit e Triptase. Pelos resultados obtidos, concluiu-se que a quantidade/densidade dos mastócitos é diferente nos tecidos foliculares de acordo com a fase de erupção, o que permite inferir que: 1) O traumatismo decorrente da mastigação sobre o conjunto "mucosa bucal com o folículo pericoronário na submucosa" pode explicar porque o epitélio reduzido exporia o esmalte às células do tecido conjuntivo; 2) A exposição das proteínas do esmalte com propriedades antigênicas corresponderia à liberação de antígenos sequestrados que levariam à interação de IgE e mastócitos em número aumentado na região; e 3) A consequente degranulação e liberação de mediadores no local, como histamina, leucotrienes, prostaglandinas, proteases, citocinas e fatores de crescimento, contribuem para a compreensão dos sinais e sintomatologia atribuídos à erupção dentária.

Assessment of fragile histidine triad expression in ameloblastoma, odontogenic keratocyst and dentigerous cyst

Background: FHIT (Fragile histidine triad) a member of tumor suppressor family, has been extensively studied in many solid tumors including head and neck squamous cell carcinoma. Among all head and neck cyst and tumors odontogenic lesions account approximately 3%-9%. The molecular pathogenesis of these lesions is less explored. Defects in cell cycle regulators and tumor suppressor genes could result in the development of odontogenic cyst and tumors. Hence, we aimed to determine the significant role of a tumor suppressor gene FHIT in most commonly occurring odontogenic lesions mainly ameloblastoma, odontogenic keratocyst and dentigerous cyst. Subjects and Methods: Immunohistochemical analysis of FHIT was done in ameloblastoma, odontogenic keratocyst, dentigerous cyst and dental follicle. Interpretation of the stained slides were done using standard scoring criteria by two pathologist. The results were subjected for statistical analysis. Results: Expression of FHIT varied among the groups, with highest negative expression in ameloblastoma 44.4% followed by odontogenic keratocyst 14% and 100%positive expression was seen in dentigerous cyst. The expression levels between the groups were statistically insignificant. Conclusion: The varied expression or negative expression of FHIT could be considered as an indicator for aggressive behavior and transformation of preneoplastic/cystic epithelium.

Why canines induce resorption of neighboring roots? An imaging correlation

ABSTRACT Despite the explanations about the mechanisms and reasons why dental follicles of unerupted maxillary canines do not cause root resorption in neighboring teeth, questions remain about the time expected for this event and the lack of protocols for preventive clinical management, which may serve as insights for further studies. Here, these mechanisms are correlated with imaging findings of CT scans and 3D reconstructions of a typical clinical case.

RESUMO Apesar das explicações dos mecanismos e dos porquês os folículos pericoronários dos caninos superiores não irrompidos podem reabsorver as raízes dos dentes vizinhos, questiona-se a inexistência de previsibilidade do tempo em que isso ocorre e a ausência de protocolos de condutas clínicas preventivas, como insights para novas pesquisas. Correlaciona-se, também, esses mecanismos com os aspectos imaginológicos de cortes tomográficos e reconstruções 3D de um caso clínico característico.

Three-Dimensional Spheroid Formation of Cryopreserved Human Dental Follicle-Derived Stem Cells Enhances Pluripotency and Osteogenic Induction Properties

BACKGROUND: Enhancement and maintenance of the stemness of mesenchymal stem cells (MSCs) is one of the most important factors contributing to the successful in vivo therapeutic application of these cells. In this regard, three-dimensional (3D) spheroid formation has been developed as reliable method for increasing the pluripotency of MSCs. Moreover, using a new protocol, we have previously shown that dental tissues of extracted wisdom teeth can be effectively cryopreserved for subsequent use as a source of autologous stem cells. The main purpose of this study is to analyze the stemness and in vitro osteogenic differentiation potential of 3D spheroid dental MSCs compared with conventional monolayer cultured MSCs. METHODS: In this study, MSC-characterized stem cells were isolated and cultured from long-term cryopreserved dental follicles (hDFSCs), and then 2D hDFSCs were cultured under 3D spheroid-forming conditions using a newly designed microchip dish. The spheroids (3D hDFSCs) thus produced were investigated and characterized with respect to stemness, MSC marker expression, apoptosis, cell cycle analysis, extracellular matrix (ECM) production, and osteogenic and adipogenic differentiation properties. RESULTS: In terms of MSC and senescence markers, spheroid cells showed no difference when compared with 2D hDFSCs; however, 3D hDFSCs were observed to have a higher proportion of cell cycle arrest and a larger number of apoptotic cells. Moreover, spheroids showed substantially increased levels of pluripotency marker (early transcription factors) and ECM protein expression. Compared with 2D hDFSCs, there was also a notable enhancement in the osteogenic induction potential of spheroids, although no differences were observed with respect to in vitro adipogenesis. CONCLUSION: To the best of our knowledge, this is the first study to demonstrate the application of a spheroid culture system for dental follicle-derived stem cells using a microchip dish. Although further studies are needed, including in vivo transplantation, the results obtained in this study indicate that spheroid hDFSCs derived from cryopreserved dental follicle tissues could be used as a valuable source of autologous stem cells for bone tissue regeneration.

Neurotrophin 3 promotes osteogenic differentiation of human dental follicle cells / 华西口腔医学杂志

OBJECTIVE@#This study aims to investigate the effect of neurotrophin 3 (NT-3) on the osteogenic differentiation of human dental follicle cells (hDFCs).@*METHODS@#hDFCs were isolated and cultured in vitro. Immunocytochemical staining was used to identify the origin of hDFCs. The effects of different NT-3 concentrations on hDFCs proliferation were detected by using CCK-8 assay. The alkaline phosphatase (ALP) activities and mRNA expression levels of bone morphogenetic protein-2 (BMP-2) and osteocalcin (OCN) were determined to investigate the effects of NT-3 on hDFCs osteogenesis. The difference in the number of mineralized nodules was detected using alizarin red staining.@*RESULTS@#Vimentin and cytokeratin staining results showed that hDFCs originated from the mesenchymal cells. NT-3 exerted no evident effect on hDFCs proliferation. The ALP activity and the BMP-2 and OCN mRNA expression levels of hDFCs were significantly improved under treatment with different NT-3 concentrations (25, 50, and 100 ng·mL ⁻¹) compared with those in the control group. BMP-2 and OCN mRNA relative expression levels of hDFCs reached the highest when the NT-3 concentration was 100 ng·mL ⁻¹. The number of mineralized nodules reached the maximum when the hDFCs were treated with 50 and 100 ng·mL ⁻¹ NT-3.@*CONCLUSIONS@#Appropriate mass concentration of NT-3 can promote the osteogenic differentiation of hDFCs.

Histopathological evaluation of dental follicles associated with impacted third molars

Aim: To histologically evaluate dental follicles of impacted third molars with no radiographic evidence of pathology. Methods: We carried out both a quantitative and qualitative analysis of pericoronal follicles removed from impacted third molars and investigated the association with clinical data. The sample included 36 extracted dental follicles of impacted third molars, obtained from 28 patients, which presented with no radiographic evidence of pathologies. Results: None of the follicles analyzed showed any pathological entity. The epithelial lining was observed in 61.1% of samples, being identified as reduced enamel epithelium. We found a significant relation between the the presence of inflammatory infiltrate and the group aged over 21 years (64.3%; p<0.05). Conclusions: Considering the absence of pathological lesions, we suggest that impacted third molars should only be extracted in young-aged individuals due to specific pathologies or indications

Effect of hypoxia on the biological characteristics of human dental follicle cells / 华西口腔医学杂志

<p><b>OBJECTIVE</b>This study aimed to investigate the effects of hypoxia on the characteristics of human dental follicle cells (hDFCs).</p><p><b>METHODS</b>The tissue explant collagenase method was used to isolate hDFCs from young permanent teeth. The immunofluorescence technique was used to detect cell surface markers, and the multi-differentiation potential was detected by multilineage differentiation induction assay. Then, the hypoxic microenvironment was physically mimicked, and the cells were divided into the normoxia group (20%O₂) and the hypoxia group (2%O₂). The effects of hypoxia on cell migration and proliferation were examined by Transwell chamber test and CCK-8 assay, respectively. The gene and protein expression levels of stemness-related markers at both oxygen concentrations were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot, respectively. After osteogenic induction of both groups, qRT-PCR was performed to evaluate the osteogenesis-related gene, and alizarin red staining was used to assess the formation of mineralized nodules.</p><p><b>RESULTS</b>With the multi-differentiation capacity of osteogenic cells, adipogenic cells, and nerves, hDFCs demonstrate strong stem cell characteristics and possess the criteria of mesenchymal stem cells, which can meet the requirements of seed cells in dental tissue engineering. Hypoxia was conducive to the maintenance of hDFC stemness. Hypoxia promoted the migration and proliferation of hDFCs. The hDFCs were induced to osteogenic differentiation under hypoxic conditions, thereby enhancing osteogenesis.</p><p><b>CONCLUSIONS</b>Hypoxic microenvironment plays an important role in maintaining the stemness and promoting the proliferation, migration, and differentiation of hDFCs. Thus, this microenvironment could also serve several important functions in future clinical applications.</p>

Naked cuticle homolog 2 positively regulates the osteogenic differentiation of rat dental follicle cells / 中华口腔医学杂志

Objective@#To examine the expression of naked cuticle homolog 2 (Nkd2) in the process of root development and osteogenic differentiation of dental follicle cells of rat (rDFC), in order to explore the molecular mechanisms of Nkd2 on the osteoblast differentiation of rDFCs.@*Methods@#Immunohistochemical analysis was used to detect the expression of Nkd2 in the base dental follicle of the mandibular first molar of rat at 1, 3, 5, 7, 9, 11 and 13 days postnatal. Mineralization nodule formation of rDFCs was detected by alizarin red staining and cetylpyridine. The change of Nkd2 during osteogenic differentiation of rDFCs was evaluated by Western blotting and the associations between Nkd2 and osteogenic cytokines of alkaline phosphatase (ALP), Runt-related transcription factor-2 (RUNX2) and osteocalcin (OCN) were examined. The rDFCs were transfected with small interfering RNA (siRNA) to knock down the expression of Nkd2 and Western blotting and quantitative real-time PCR (qPCR) were adopted to explore the effects of Nkd2 on osteogenic differentiation by detecting variations of Nkd2 and osteogenic factors ALP, RUNX2, OCN among silencing group (Si), negative control RNA group (Nc) and mock control group (Mock), respectively.@*Results@#The expression of Nkd2 in the base dental follicle of the mandibular first molar of rat was time dependent. Mineralization nodules of rDFCs and absorbance of cetylpyridine after osteogenic induction increased gradually (the absorbances of cetylpyridine were 0 week: 0.017±0.005, 1 week: 0.702±0.044, 2 weeks: 1.812±0.531, 3 weeks: 2.767±0.253, respectively). Results of Western blotting showed that Nkd2 (1.60±0.23) of mineralization group was significantly higher than that of control group (1) (P<0.05) at the early stage of osteogenic differentiation along with the expression of other osteogenic factors. The protein and mRNA of Nkd2 and osteogenic factors were significantly decreased in Si group compared with Nc and Mock groups (P<0.05), and no changes between Nc and Mock groups were observed. The changes of protein in Si, Nc and Mock groups were Nkd2: 0.42±0.10, 1.12±0.07, 1, ALP: 0.70±0.15, 1.11±0.14, 1, RUNX2: 0.58±0.08, 0.93±0.08, 1 and OCN: 0.64±0.06, 0.99±0.02, 1, respectively. The mRNA variances in Si, Nc and Mock groups were Nkd2: 0.39±0.05, 0.96±0.10, 1, ALP: 0.15±0.13, 1.01±0.07, 1, RUNX2: 0.39±0.31, 0.97±0.13, 1, OCN: 0.17±0.08, 1.08±0.21, 1, respectively.@*Conclusions@#Nkd2 participates in the root development process in rat and may acts as a positive role in the early stage of osteogenic differentiation of rDFCs in rat.

The effects of human dental pulp stem cells-conditioned medium on the osteogenic differentiation of human dental follicle stem cells in vitro / 实用口腔医学杂志

Objective:To evaluate the effects of human dental pulp stem cells-conditioned medium(HDPSCs-CM)on the osteogenic differentiation of human dental follicle stem cells(HDFSCs) in vitro.Methods:HDFSCs were in vitro cultured,purified and identified.CCK-8 assay was applied to evaluate the HDFSCs viability after 7 days cultured by HDPSCs-CM;the morphological changes of HDFSCs were observed;the osteogenic differentiation was studied by alkaline phosphatase(ALP) staining and alizarin red staining.The mRNA expression of POSTN,Col-Ⅰ,ALP,BSP and OPN was detected by Real-Time PCR.Results:Induced by HDPSCs-CM,HDFSCs exhibited several characteristics of cementoblast or osteoblast lineages.In the induction group the viability of HDFSCs was inhibited(P<0.05 or P<0.01),ALP staining was stronger and there were more mineralized nodules,the expression levels of POSTN,Col-Ⅰ,ALP,BSP and OPN were upregulated(P<0.05 or P<0.01).Conclusion:HDPSCs-CM can promote the osteogenic differentiation of HDFSCs.

Cambios histopatológicos de los folículos dentales en relación al espacio pericoronario y posición de terceros molares no erupcionados / Histopathological changes in dental follicles in relation to pericoronal spaces and position of the unerupted third molars

Objetivos: Determinar los cambios histopatológicos de los folículos dentales, en relación al espacio pericoronario y la posición de terceros molares no erupcionados. Material y Métodos: Se incluyeron en la investigación 128 folículos dentales, extraídos de 105 pacientes de ambos sexos. La medida de los espacios pericoronarios y la posición de los terceros molares fueron obtenidas de las radiografías panorámicas. Las muestras foliculares se enviaron para su estudio histológico; fueron fijadas en formol al 10% y coloreadas con Hematoxilina-Eosina, para posteriormente ser leídas por un Patólogo Oral. Los datos obtenidos fueron anotados en fichas para luego ser evaluadas estadísticamente mediante la prueba de chi-cuadrado. Resultados: De los participantes, 60,9% eran del sexo femenino y el 39.1% del masculino con edades entre 15 a 49 años. Se encontró un (76,6%) de cambios histopatológicos foliculares. La relación de los cambios histopatológicos y la medida de espacios pericoronarios no fue estadísticamente significativa (p=0,470), sin embargo se observó una alta prevalencia de patología folicular (75,7%) en el grupo de medidas =2,5mm, donde no debió observarse alteraciones. La relación entre cambios histopatológicos y la posición IB del tercer molar (90,9%) según la clasificación de Pell y Gregory fue estadísticamente significativa (p=0,031). Conclusiones: Los cambios histopatológicos en etapas tempranas no son observables radiográficamente, por lo que es indispensable el estudio histológico complementario. Se recomienda extraer profilácticamente los terceros molares no erupcionados, para evitar el desarrollo de patología folicular y enviar de manera rutinaria todas las muestras foliculares para su estudio histológico.

Objectives: To determine the histopathological changes of the dental follicles in relation to pericoronary space and the position of un erupted third molars. Material and Methods:128 dental follicles taken from105 patients of both sexes were included in the research. The measurement of pericoronal spaces and position of the third molars were obtained from panoramic radiographs. Follicular samples were sent for histological study; they were fixed in10% formalin and stained with hematoxylin-eosin and then were read by an oral pathologist. The data were recorded on cards and then been evaluated statistically using the chi-square test. Results: Of the participants, 60.9% were femaleand 39.1% of men aged15-49years. One (76.6%) follicular histopathological changes were found. The relationship between histopathological changes and measure spaces pericoronal was not statistically significant (p =0.470), but a high prevalence of follicular pathology (75.7%) were observed in the group of measures=2.5mm, where should not be changes. The relationship between histopathological changes and IB position of the third molar (90.9%) according to the classification of Pelland Gregory was statistically significant (p =0.031). Conclusions: Histopathological changes at early stages are not observable radiographically, so the complementary histology is indispensable. It is recommended prophylactically extract unerupted third molars to prevent follicular pathology development and routinely send all follicular samples for histological examination.

Gene regulatory network during the osteogenic differentiation process of dental follicle stem cells:A bioin-formatic analysis / 实用口腔医学杂志

Objective:To study the gene regulatory network during the osteogenic differentiation process of dental follicle stem cells (DFSCs)with bioinformatic analysis.Methods:The differentially expressed genes during the osteogenic diffrentiation process of DF-SCs were selected from the GEO Datasets.Then the relationship among the genes were analysed using DAVID and GeneMANIA data-base.Results:Numerous differentially expressed genes during the osteogenic differentiation process of DFSCs were obtained,289 genes with significance of different expression(P <0.05)were enriched into “cell differentiation”,“cell proliferation”,“skeletal sys-tem development”and “calcium signaling pathway”subgroups.ALPL,CTSK,TUFT1 ,TGFBR2,FHL2,ROR2,STC1 ,POSTN, ZBTB1 6,FRZB,PRELP and IGFBP5 were enriched into the “skeletal system development”subgroup.The 1 2 genes exhibited interac-tions,including co-expression,co-localization,genetic interaction and signal pathways.Conclusion:There is a complex molecular regulatory network among the differentially expressed genes during the osteogenic differentiation process of DFSCs.It is necessary to an-alyse the osteogenic differentiation process of DFSCs as a whole from WNT,TGFbeta,MAPK siganal pathyways,Homeobox transcrip-tion factors and osteogenic differentiation marker genes.

Expression and significance of wingless-type MMTV integration site family, member 5A/receptor tyrosine kinase-like orphan receptor 2 in the rat dental follicle / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To observe the expression of wingless-type MMTV integration site family, member 5A (Wnt5A)/receptor tyrosine kinase-like orphan receptor 2 (Ror2) signal in the dental follicle cells during the normal eruption of the teeth as well as to explore the relationship between the expression of dental follicle cells and the formation of mature osteoclasts and eruption of the teeth.</p><p><b>METHODS</b>The mandibulars of 1-13 d old SD rats were separated to observe the growth and develop-ment of the teeth and alveolar bone through hematoxylin-eosin(HE) staining. Ror2 and Wnt5A expressions in rat dental follicle were also observed through immunohistochemistry. Dental follicle cells from the lower first intact molar germs of 5-6-day old SD rats were separated and cultured.</p><p><b>RESULTS</b>On the second day after birth, the dental follicle began to differentiate into periodontal tissues, but no obvious changes were observed in the alveolar bone one to three days after birth. On the fourth day, the number of osteoclasts increased significantly. The results of immunohistochemistry showed that Wnt5A was not significantly expressed in rat dental follicle tissues before the fourth day, but positive expression was expressed in the next day and continued to express to thirteenth days. Ror2 was expressed in the rat dental follicle at postnatal days 1-3, but weak expression was found in days 4-13.</p><p><b>CONCLUSIONS</b>Wnt5A and Ror2 expressions in the process of tooth eruption have specific time distributions, suggesting that these expressions may participate in the regulation of the eruption of the teeth.</p>

Progress in the study of dental tissue-derived stem cells / 实用口腔医学杂志

Dental stem cells(DSCs)possess the characteristics of stem cells and can be effectively obtained from iatro-waste products (such as impacted wisdom tooth and the extracted teeth for orthodontic reason).It has been proved that DSCs are the important sources of stem cells for tissue engineering and regenerative medicine research.Research of these stem cells will create broader space for tissue engi-neering and regenerative medicine and will have important values in translational research.This review gives an overview of the research pro-gress of dental stem cells,and presents some new findings of several common dental stem cells as well as the application in tissue regenera-tion.

Comparison of proliferative activity of epithelial cells between the follicles of impacted teeth / Comparación de la actividad proliferativa de las células epiteliales entre los folículos de dientes impactados

The aim of this comparative observational study was to compare the proliferative activity of dental follicles surrounding impacted maxillary canines and mandibular third molars. Following extraction, forty follicles of the impacted mandibular third molars and 40 follicles of the impacted maxillary canines were removed. Epithelial cell proliferative activity of these samples was assessed using immunohistochemical labeling for Ki-67, minichromosome maintenance 2 (MCM-2) protein and epithelial growth factor receptor (EGFR). Intensity and extent of Ki-67, MCM-2 and EGFR expressions were evaluated by a scoring formula. The lining epithelium of the maxillary canine follicles had mean scores of 4.65±0.27 for Ki-67, 1.25±0.33 for MCM-2 and 7.30±0.23 for EGFR which were not significantly different than those expressed in the mandibular third molar follicles (4.46±0.26 for Ki-67, 1.39±0.33 for MCM-2 and 7.21±0.20 for EGFR). The expression of Ki-67 and MCM-2 could not be detected in the epithelial remnants within the connective tissue in both groups. EGFR expression, detected in the epithelial remnants in both groups, was not significantly different (7.28±0.14 in the canine group as opposed to 7.21±0.16 in the third molar group). Based on these findings, it can be deduced that impacted mandibular third molars and maxillary canines carry similar risk of pathology development.

El objetivo fue comparar la actividad proliferativa de los folículos dentarios que rodean a dientes caninos maxilares y terceros molares mandibulares impactados. Luego de realizada la extracción dentaria, se removieron 40 folículos dentarios de los terceros molares mandibulares impactados y 40 de caninos maxilares impactados. Se evaluó la actividad proliferativa de las células epiteliales de estas muestras mediante marcaje inmunohistoquímico para Ki-67, para la proteína de mantenimiento minicromosoma 2 (MCM-2) y para el receptor del factor de crecimiento epitelial (EGFR). Se evaluó la intensidad y extensión de Ki-67, MCM-2 y las expresiones de EGFR mediante una fórmula de puntuación. El epitelio de revestimiento de los folículos correspondientes a los caninos maxilares presentaron valores promedios de 4,65±0,27 para Ki-67, 1,25±0,33 para MCM-2 y 7,30±0,23 para EGFR, que no fueron significativamente diferentes de los expresados en los folículos de terceros molares mandibulares (4,46±0,26 para Ki-67, 1,39±0,33 para MCM-2 y 7,21±0,20 para EGFR). La expresión de Ki-67 y MCM-2 no pudo ser detectada en los restos epiteliales dentro del tejido conectivo en ambos grupos. La expresión de EGFR, detectada en los restos epiteliales en ambos grupos, no fue significativamente diferente (7,28±0,14 en el grupo de los caninos, y 7,21±0,16 en el grupo de los terceros molares). Sobre la base de estos resultados, se puede deducir que la retención de terceros molares y caninos maxilares conlleva un riesgo similar para el desarrollo de patología.

Immunohistochemical study of polycystin-1 in dentigerous cysts.

Background: The alterations involved in step-wise transformation of a dental follicle to dentigerous cyst (DC) is not clearly known. Primary cilium and its protein have been hypothesized to be associated with DC. Mutation of a ciliary protein, polycystin‑1 (PC1) is associated with autosomal dominant polycystic kidney disease. This study was performed to assess the immunohistochemical expression of PC1 between DC and postfunctional follicular tissue (PFFT). Materials and Methods: Thirty‑one consecutive PFFT and 15 DC formed the study group. The PFFT and DC tissues were stained with antibody against PC1. Statistical Package for Social Service was used to analyze data. Descriptive statistics and Student’s Chi‑square test were appropriately used. P ≤0.05 was taken as significant. Results: Fifteen DC (100%) and 7 (22.58%) PFFT were positive for PC1. The difference was statistically significant (P = 0.000). PC1 expression was observed in the cytoplasm with varying intensity. Discussion and Conclusion: All PC1 positive epithelial cells’ cytoplasm stained diffusely. Abnormal cytoplasmic expression of PC1 in all positive epithelial lining indicates that the PC1 probably is associated with cystic transformation.

Immunohistochemical analysis of CK 18 in dental follicles of impacted third molars: A pilot study.

Objective: Odontogenic tumors are lesions derived from epithelial, ectomesenchymal, and/or mesenchymal elements that still are, or have been, part of the tooth-forming apparatus. Approximately 80% of odontogenic tumors occur in the mandible, with a marked predilection for the posterior region, and are often associated with an unerupted tooth. The aim of this study was to determine whether cytokeratin (CK) 18 immunostaining decorated the follicular tissue removed at the time of prophylactic extraction of impacted mandibular third molars, which might suggest oncofetal transformation. Materials and Methods : Fifty-four impactions met the study inclusion criteria, of which 24 cases showed the presence of reduced enamel epithelium and/or connective tissue with odontogenic epithelium, which were subjected to CK 18 immunostaining. Results: All 24 cases with adequate epithelium were CK 18 immunonegative. Conclusion: There was no oncofetal transformation in the odontogenic epithelia of the dental follicles studied. Thus, although we reaffirm that evaluation of follicular tissue is imperative since disease conditions may be found in minute follicular spaces, development of odontogenic cysts and tumors is unlikely.