In Vitro and In Vivo Evaluation of a Polycaprolactone (PCL)/Polylactic-Co-Glycolic Acid (PLGA) (80:20) Scaffold for Improved Treatment of Chondral (Cartilage) Injuries.

Articular cartilage is a specialized tissue that provides a smooth surface for joint movement and load transmission. Unfortunately, it has limited regenerative capacity. Tissue engineering, combining different cell types, scaffolds, growth factors, and physical stimulation has become an alternative for repairing and regenerating articular cartilage. Dental Follicle Mesenchymal Stem Cells (DFMSCs) are attractive candidates for cartilage tissue engineering because of their ability to differentiate into chondrocytes, on the other hand, the polymers blend like Polycaprolactone (PCL) and Poly Lactic-co-Glycolic Acid (PLGA) have shown promise given their mechanical properties and biocompatibility. In this work, the physicochemical properties of polymer blends were evaluated by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM) and were positive for both techniques. The DFMSCs demonstrated stemness by flow cytometry. The scaffold showed to be a non-toxic effect when we evaluated it with Alamar blue, and the samples were analyzed using SEM and phalloidin staining to evaluate cell adhesion to the scaffold. The synthesis of glycosaminoglycans was positive on the construct in vitro. Finally, the PCL/PLGA scaffold showed a better repair capacity than two commercial compounds, when tested in a chondral defect rat model. These results suggest that the PCL/PLGA (80:20) scaffold may be suitable for applications in the tissue engineering of articular hyaline cartilage.

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.

An Imaging Perspective to Multiple Calcifying Hyperplastic Dental Follicles - A Report of Three Cases.

Rationale: Multiple Calcifying Hyperplastic Dental Follicle (MCHDF) is an extremely rare condition and is characterised by multiple impacted permanent teeth, with enlarged dental follicles, containing calcifications. Cone-beam computed tomography (CBCT) is the ideal exam for the identification of this condition. Patient Concerns: The present study seeks to compare the behaviour of MCHDF in imaging exams of three clinical cases with their MCHDF imaging diagnoses, in which a change about tooth eruption was observed. Diagnosis: CBCT proved to be an important diagnostic tool for MCHDF, as it is able to identify these small calcifications, as well as measure the size of the follicle.Treatment Outcomes and Take. Away Lessons: With a consistent imaging diagnosis, less invasive treatments become a viable option for this condition, since functional and aesthetic involvement is common in these patients, who often tend to be quite young.

Revisiting the human dental follicle: From tooth development to its association with unerupted or impacted teeth and pathological changes.

Dental follicles are involved in odontogenesis, periodontogenesis, and tooth eruption. Dental follicles are unique structures, considering that their remnants can persist within the jawbones after odontogenesis throughout life if the tooth does not erupt. Pathological changes may occur in these tissues as individuals age. The changes range from benign to life threatening. Thus, the assessment of age-related changes in dental follicles associated with unerupted teeth is of paramount importance. In this review, we summarize the physiological roles and changes in dental follicles in odontogenesis, tooth eruption, and aging, in addition to the pathological changes associated with these structures. We encourage investigators to consider this peculiar tissue as a unique model and explore its potential to clarify its importance from the viewpoints of developmental biology, tissue physiology, and pathology.

Similar Features, Different Behaviors: A Comparative In VitroStudy of the Adipogenic Potential of Stem Cells from Human Follicle, Dental Pulp, and Periodontal Ligament.

Dental tissue-derived mesenchymal stem cells (DT-MSCs) are a promising resource for tissue regeneration due to their multilineage potential. Despite accumulating data regarding the biology and differentiation potential of DT-MSCs, few studies have investigated their adipogenic capacity. In this study, we have investigated the mesenchymal features of dental pulp stem cells (DPSCs), as well as the in vitro effects of different adipogenic media on these cells, and compared them to those of periodontal ligament stem cells (PLSCs) and dental follicle stem cells (DFSCs). DFSC, PLSCs, and DPSCs exhibit similar morphology and proliferation capacity, but they differ in their self-renewal ability and expression of stemness markers (e.g OCT4 andc-MYC). Interestingly, DFSCs and PLSCs exhibited more lipid accumulation than DPSCs when induced to adipogenic differentiation. In addition, the mRNA levels of adipogenic markers (PPAR, LPL, and ADIPOQ) were significantly higher in DFSCs and PLSCs than in DPSCs, which could be related to the differences in the adipogenic commitment in those cells. These findings reveal that the adipogenic capacity differ among DT-MSCs, features that might be advantageous to increasing our understanding about the developmental origins and regulation of adipogenic commitment.

Age-Related Metabolic Pathways Changes in Dental Follicles: A Pilot Study.

Aging is not a matter of choice; it is our fate. The "time-dependent functional decline that affects most living organisms" is coupled with several alterations in cellular processes, such as cell senescence, epigenetic alterations, genomic instability, stem cell exhaustion, among others. Age-related morphological changes in dental follicles have been investigated for decades, mainly motivated by the fact that cysts and tumors may arise in association with unerupted and/or impacted teeth. The more we understand the physiology of dental follicles, the more we are able to contextualize biological events that can be associated with the occurrence of odontogenic lesions, whose incidence increases with age. Thus, our objective was to assess age-related changes in metabolic pathways of dental follicles associated with unerupted/impacted mandibular third molars from young and adult individuals. For this purpose, a convenience sample of formalin-fixed paraffin-embedded (FFPE) dental follicles from young (<16 y.o., n = 13) and adult (>26 y.o., n = 7) individuals was selected. Samples were analyzed by high-performance liquid chromatography-mass spectrometry (HPLC-MS)-based untargeted metabolomics. Multivariate and univariate analyses were conducted, and the prediction of altered pathways was performed by mummichog and Gene Set Enrichment Analysis (GSEA) approaches. Dental follicles from young and older individuals showed differences in pathways related to C21-steroid hormone biosynthesis, bile acid biosynthesis, galactose metabolism, androgen and estrogen biosynthesis, starch and sucrose metabolism, and lipoate metabolism. We conclude that metabolic pathways differences related to aging were observed between dental follicles from young and adult individuals. Our findings support that similar to other human tissues, dental follicles associated with unerupted tooth show alterations at a metabolic level with aging, which can pave the way for further studies on oral pathology, oral biology, and physiology.

Alterações idade-dependente nas vias metabólicas de folículos dentários: um estudo piloto / Age-related metabolic pathways changes in dental follicles: a pilot study

Envelhecer não é uma escolha; é nosso destino. O declínio funcional dependente do tempo que afeta a maioria dos organismos vivos está vinculado às alterações em variados processos celulares, incluindo senescência celular, alterações epigenéticas, instabilidade genômica, exaustão de células-tronco, entre outras. As alterações morfológicas relacionadas à idade nos folículos dentários associados a dentes não-erupcionados têm sido investigadas há décadas, principalmente motivado pelo fato de que cistos e tumores podem surgir em associação a dentes inclusos e/ou impactados. Quanto mais entendemos a fisiologia dos folículos dentários, mais nos tornamos capazes de contextualizar eventos biológicos que podem estar associados à ocorrência de lesões odontogênicas cuja incidência aumenta com a idade. Assim, nosso objetivo foi avaliar as alterações metabólicas relacionadas à idade em amostras de folículos dentários associados à terceiros molares inferiores inclusos/impactados de indivíduos adolescentes e adultos. Uma amostra de conveniência de folículos dentários fixados em formalina e embebidos em parafina de indivíduos adolescentes (<16 anos, n= 13) e adultos (>26 anos, n= 7) foi selecionada. As amostras foram preparadas e submetidas à cromatografia líquida de alta eficiência acoplada a espectrometria de massa (HPLC-MS) em análise metabolômica untargeted. Análises uni- e multivariadas foram conduzidas, e a previsão de vias alteradas foi realizada pelas abordagens mummichog e GSEA. Folículos dentários de indivíduos adolescentes e adultos mostraram diferenças nas vias relacionadas à biossíntese do hormônio esteróide C21, biossíntese dos ácidos biliares, metabolismo da galactose, biossíntese de androgênio e estrogênio, metabolismo do amido e sacarose e metabolismo do lipoato. Nossos achados sugerem que, assim como outros tecidos humanos, os folículos dentários associados a dentes não erupcionados apresentam, durante o envelhecimento, alterações em nível metabólico, o que pode abrir caminho para novos estudos sobre biologia, fisiologia e patologia oral.

Aging is not a matter of choice; it is our fate. The 'time-dependent functional decline that affects most living organisms' is coupled with several alterations in cellular processes, including cell senescence, epigenetic alterations, genomic instability, stem cell exhaustion, amongst others. Age-related morphological changes in dental follicles have been investigated for decades, mainly motivated by the fact that cysts and tumors may arise in association with a unerupted and/or impacted teeth. The more we understand dental follicles' physiology, the more we become able to contextualize biological events that can be associated with the occurrence of odontogenic lesions which incidence increases with age. Thus, our objective was to assess age-related changes in metabolic pathways of dental follicles associated with unerupted/impacted mandibular third molars from young and adult individuals. For this purpose, a convenience sample of formalin-fixed paraffin-embedded dental follicles from young (<16 y.o., n = 13) and adult (>26 y.o., n = 7) individuals was selected. Samples were analyzed by high-performance liquid chromatography-mass spectrometry (HPLC-MS)-based untargeted metabolomics. Multivariate and univariate analyses were conducted, and the prediction of altered pathways was performed by mummichog and GSEA approaches. Dental follicles from young and older individuals showed differences in pathways related to C21-steroid hormone biosynthesis, bile acid biosynthesis, galactose metabolism, androgen and estrogen biosynthesis, starch and sucrose metabolism and lipoate metabolism. Our findings support that similar to other human tissues, dental follicles associated with unerupted tooth show alterations at a metabolic level with aging, which can pave the way for further studies on oral pathology, oral biology and physiology.

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.

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.

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.

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

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.

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 analysis of human homologue of drosophila patched (PTCH) in dental follicles of impacted third molars / Análisis imunohistoquímico del homólogo humano del gen parcheado de drosofila (PTCH) en folículos dentales de terceros molares retenidos

This study investigated the immunodetection of PTCH in epithelial components of dental follicles associated with impacted third molars without radiographic signs of pathosis. One hundred and five specimens of dental follicles associated with impacted third molars with incomplete rhizogenesis (between Nolla's stage 6 and 9) were surgically removed from 56 patients. Epithelial cell proliferation was determined by using immunohistochemical labeling. Statistical analysis was performed using Fisher exact test and a level of significance of 5 percent. Of the 105 dental follicles collected, 3 were PTCH-positive. The specimens with squamous metaplasia and epithelial hyperplasia had higher rates of positivity for PTCH, as well as those with active remnants of odontogenic epithelium. This study suggests that the odontogenic cells of the dental follicle might be proliferating during the rhizogenesis, while the squamous metaplasia and hyperplasia of the epithelial lining and proliferative odontogenic epithelial rests show the differentiation potential of dental follicles.

Se investigó la inmunodetección de PTCH en los componentes epiteliales de los folículos dentales asociados a terceros molares retenidos sin signos radiográficos y morfológicos de patología. Fueron quirúrgicamente extraídos de 56 pacientes 105 muestras de folículos dentales asociadas a terceros molares retenidos con rizogénesis incompleta (entre el estadio de Nolla 6 y 9). La proliferación de células epiteliales se deteminó mediante inmunohistoquímica. El análisis estadístico se realizó mediante la prueba exacta de Fisher. De los 105 folículos dentales recogidos, 3 fueron PTCH-positivos. Las muestras con metaplasia escamosa e hiperplasia epitelial tuvieron mayores tasas de positividad para PTCH, así como aquellos con los restos de proliferación del epitélio odontogénico. En conclusión, este estudio sugiere que las células odontogénicas del folículo dental podrían estar proliferando durante la rizogénesis, mientras que la metaplasia escamosa e hiperplasia del epitelio y de restos epiteliales odontogénicos en proliferación muestran el potencial de diferenciación de los folículos dentales.

Collagen and elastic fibers in odontogenic entities: analysis using light and confocal laser microscopic methods.

Dentigerous cyst (DC) and keratocystic odontogenic tumor (KOT) are odontogenic lesions arising from epithelial elements, such as those observed in dental follicles (DF), that have been part of the tooth forming apparatus. These lesions show different clinical and histological characteristics, as well as distinct biological behavior. This study aimed to qualify and quantify collagen and elastic fibers by means of histochemical techniques with light and confocal laser microscopic methods in three odontogenic entities. Eleven DF, 13 DC (n=10 with inflammation, n=3 without inflammation) and 13 KOT were processed to the following techniques: Hematoxylin and Eosin, Masson's Trichrome, Picrosirius, Direct Blue, and Orcein. DF and DC without inflammation exhibited collagen with similar characteristics: no parallel pattern of fiber orientation, thick fibers with dense arrangement, and absence of distinct layers. A comparison between DC with inflammation and KOT revealed similar collagen organization, showing distinct layers: thin collagen fibers with loose arrangement near the epithelium and thick fibers with dense arrangement in distant areas. The only difference found was that KOT exhibited a parallel collagen orientation in relation to the odontogenic epithelia. It may be suggested that the connective tissue of DC is a reactive tissue, inducing an expansive growth associated with fluid accumulation and inflammatory process, which in turn may be present as part of the lesion itself. In KOT, loosely arranged collagen may be associated with the behavior of the neoplastic epithelium.