Shear bond strength of the adhesive/dentin interface after different etching protocols.

Background: Lack of bond stability between the composite resin and dentin remains one of the main reasons for having to replace esthetic restorations. Aim: This study aimed to evaluate the influence of chlorhexidine (CHX) on the bond strength of a total etching system to dentin tissue after degradation of the adhesive interface. Materials and Methods: One hundred and eighty fragments of human molars were divided into three groups (n = 15) according to the materials used during the acid-etching step: Group 1 (control), 37% phosphoric acid; Group 2, a combined solution of 37% phosphoric acid and 2% CHX; and Group 3, 37% phosphoric acid followed by 2% CHX. Following the restorative procedures, the groups were divided into four subgroups according to the number of thermal cycles (TC) and to the time of storage in water (SW), and then subjected to a shear strength test, until fracture: (A) 0 TC/24-h SW; (B) 500 TC/1-week SW; (C) 2,000 TC/1-month SW; and (D) 12,000 TC/6-month SW. Two-way analysis of variance and Duncan's complementary test were used to perform multiple comparisons. Results: After the 24-h and 1-week SW time periods, no statistically significant difference was found among the shear strength values of the control and the experimental groups: 5.48 ± 0.59 MPa, 5.44 ± 0.56 MPa, and 5.65 ± 0.94 MPa for G1, G2, and G3, respectively. However, the shear strength values decreased significantly in all the study groups after 1 month, namely 3.60 ± 0.41 MPa, 3.08 ± 0.65 MPa, and 3.49 ± 0.23 MPa for G1, G2, and G3, respectively. After 6 months, similar results were found for G1 and G3, namely 2.77 ± 0.58 MPa and 1.74 ± 0.52 MPa, respectively, whereas the 0.77 ± 0.26 MPa value found for G2 was significantly lower than those found for the G1 and G3 groups. No differences were found between the groups with respect to fracture-type frequencies. Conclusion: The use of CHX as an agent to rehydrate the dentin had a negative influence on bond strength.

Infantile osteopetrosis associated with osteomyelitis.

Osteopetrosis is a rare inherited disorder characterised by the inability to reabsorb and remodel bone due to an osteoclast dysfunction. An increase in bone mass and density results in severe skeletal malformation and bone marrow failure, which may be fatal. The aim of this study was to report a case of infantile osteopetrosis in a 6-year-old boy, who primarily complained of dental problems. The patient developed an osteomyelitis after a primary tooth extraction. We also reviewed the literature about this genetic bone disease, since the management of dental problems of these patients can be a challenge to the dentist. The diagnosis, clinical and radiographic features and treatment of the case were discussed in this work.

Impacted permanent incisors associated with compound odontoma.

Odontomas are the most common odontogenic tumours of the maxillary bones, characterised by a slow growth and benign behaviour. They are usually small, asymptomatic and diagnosed after routine radiographic examination. The aim of this study was to report a case of a compound odontoma in the anterior maxilla of a 7-year-old girl, which was causing the impaction of the maxillary right central and lateral incisors, as well as the prolonged retention of the corresponding primary teeth. We also aimed to review the literature about these tumours, since they are not part of the dentist's day-to-day clinical practice. The clinical and radiographic features, the diagnosis and treatment of the case were discussed in this work.

Immunological characteristics of mesenchymal stem cells.

Although bone marrow is the main source, mesenchymal stem cells have already been isolated from various other tissues, such as the liver, pancreas, adipose tissue, peripheral blood and dental pulp. These plastic adherent cells are morphologically similar to fibroblasts and have a high proliferative potential. This special group of cells possesses two essential characteristics: self-renewal and differentiation, with appropriate stimuli, into various cell types. Mesenchymal stem cells are considered immunologically privileged, since they do not express costimulatory molecules, required for complete T cell activation, on their surface. Several studies have shown that these cells exert an immunosuppressive effect on cells from both innate and acquired immunity systems. Mesenchymal stem cells can regulate the immune response in vitro by inhibiting the maturation of dendritic cells, as well as by suppressing the proliferation and function of T and B lymphocytes and natural killer cells. These special properties of mesenchymal stem cells make them a promising strategy in the treatment of immune mediated disorders, such as graft-versus-host disease and autoimmune diseases, as well as in regenerative medicine. The understanding of immune regulation mechanisms of mesenchymal stem cells, and also those involved in the differentiation of these cells in various lineages is primordial for their successful and safe application in different areas of medicine.

Isolation and culture of stem cells derived from dental pulp of permanent teeth: a successful method / Isolation and culture of stem cells derived from dental pulp of permanent teeth: a successful method

Objective: To establish cultures of cells from the pulp of permanent teeth by the explant method assessing parameters usually presented by stem cells, such as the expression of certain markers and the differentiation ability into osteogenic, adipogenic, and chondrogenic lineages. This study also aimed to assess the expression of ALDH1 (aldehyde dehydrogenase 1) enzyme activity on the isolated cells. Materials and method: The pulp tissue, obtained from wisdom teeth, was placed in a 6-well plate containing proper culture medium, and stored at 37 °C and 5% CO2 for cell proliferation and plastic adherence. Cells were tested for the expression of surface markers and for ALDH1 enzyme activity, by flow cytometry. In addition, cells were assessedfor multi-differentiation potential. Results: The isolated cells showed high expression of CD44 (98.8%), CD73 (100%), and CD90 (97.2%), and moderate expression of STRO-1 (18.4%) and ALDH1 (16.2%), by flow cytometry. Similarly, the cells showed differentiation ability into all three lineages of cells tested. Conclusion: Our results suggest that the explant method - or cell proliferation method - is suitable for the isolation and cultureof stem cells from dental pulp of permanent teeth. The isolated cells may be considered stem cells, based on the current criteria for their characterization, such as plastic adherence, expression of certain markers, and the absence of others, as well as multi-differentiation potential, which showed to be promising for the application in tissue regeneration.

Stem cells and their niches: importance in tissue engineering applied to dentistry / Células-tronco e seus nichos: importância na engenharia de tecidos aplicada à odontologia

Niches are special microenvironments in tissue where stem cells are located. At these sites, which are a compound of stromal cells, extracellular matrix and soluble factors, complex molecular interactions that maintain the essential properties of stem cells occur, such as self-renewal and differentiation into multiple lineages, according to the organism?s needs. Some adult stem cell niches have already been described, but the majority of them remain unclear, including the dental pulp stem cell niches. Dental pulp stem cells have been isolated from deciduous and permanent teeth and have the potential to self-renew and differentiate. However, little is known about the exact anatomic location of these cells, and the relationship between stem cells and surrounding cells in dental pulp. Understanding how stem cells behave in the niche is extremely important in order to extract these cells from their natural habitat, expand them in vitro and transplant the stem cells back to the patient, to repair and/or regenerate tissues and organs, with no risks to the individual?s integrity. Likewise, the knowledge of stem cell biology is crucial to the development of stem cell therapies, based on tissue engineering applied to dentistry, seeking the regeneration of dental tissues damaged or lost by caries, trauma or genetic diseases.

Os nichos são microambientes especiais nos tecidos onde células-tronco de várias origens estão localizadas. Nestes sítios específicos, formados por vários tipos de células, matriz extracelular e fatores solúveis, complexas interações moleculares ocorrem para que a célulatroncomantenha sua capacidade de autorrenovação e permaneça no seu estado indiferenciado ou se especialize em determinada linhagemcelular, atendendo desta maneira as necessidades do organismo. Alguns nichos de células-tronco adultas já foram descritos, embora a maioriapermaneça desconhecida, como o das células-tronco pulpares. As células-tronco pulpares, já foram isoladas tanto de dentes decíduos comode permanentes e apresentam as características essenciais de uma célula-tronco, como capacidade de autorrenovação e multi-diferenciação.Apesar disso, pouco se sabe a respeito da localização anatômica destas células na polpa, assim como as possíveis interações funcionais entreas células-tronco pulpares e as células do estroma circundante. O entendimento de como as células-tronco interagem com o microambienteonde estão inseridas é essencial para que se possa extrair as mesmas do seu habitat natural, cultivá-las in vitro e aplicá-las em diferentessítios para que promovam o reparo e/ou regeneração de tecidos e órgãos, sem que isso represente um risco à integridade do organismo. Da mesma forma, o conhecimento de como estas células se comportam e respondem ao meio é fundamental para o desenvolvimento de terapias baseadas na utilização de células-tronco, que através da engenharia de tecidos aplicada à odontologia, visa à reestruturação de tecidos dentários danificados e/ou perdidos por cárie, trauma ou distúrbios genéticos.

Immunological characteristics of mesenchymal stem cells

Although bone marrow is the main source, mesenchymal stem cells have already been isolated from various other tissues, such as the liver, pancreas, adipose tissue, peripheral blood and dental pulp. These plastic adherent cells are morphologically similar to fibroblasts and have a high proliferative potential. This special group of cells possesses two essential characteristics: self-renewal and differentiation, with appropriate stimuli, into various cell types. Mesenchymal stem cells are considered immunologically privileged, since they do not express costimulatory molecules, required for complete T cell activation, on their surface. Several studies have shown that these cells exert an immunosuppressive effect on cells from both innate and acquired immunity systems. Mesenchymal stem cells can regulate the immune response in vitro by inhibiting the maturation of dendritic cells, as well as by suppressing the proliferation and function of T and B lymphocytes and natural killer cells. These special properties of mesenchymal stem cells make them a promising strategy in the treatment of immune mediated disorders, such as graft-versus-host disease and autoimmune diseases, as well as in regenerative medicine. The understanding of immune regulation mechanisms of mesenchymal stem cells, and also those involved in the differentiation of these cells in various lineages is primordial for their successful and safe application in different areas of medicine.

Células-tronco mesenquimais e sua aplicação na Odontologia / Mesenchymal stem cells and their application in Dentistry

Este estudo teve como objetivo realizar uma revisão de literatura sobre as células-tronco pulpares, células indiferenciadas que possuem uma elevada capacidade de proliferação, autorrenovação e diferenciação em variados tipos celulares e seu uso na engenharia de tecidos aplicada à Odontologia. Bases de dados: As bases de dados utilizadas foram Pubmed e Bireme. Seleção dos trabalhos: Foi realizada por meio das palavras-chave: “Células-tronco mesenquimais”; “Polpa dentária”; “Bioengenharia”. Conclusões: A capacidade de multidiferenciação, as altas taxas de proliferação e o acesso relativamente fácil fazem da polpa de dentes decíduos e permanentes uma atraente fonte de células-tronco mesenquimais, as quais poderiam ser empregadas na regeneração tecidual. Algumas pesquisas evidenciaram que células-tronco pulpares foram capazes de produzir tecidos dentários como dentina, polpa e até estruturas similares a dentes in vivo. Os avanços dos estudos utilizando células-tronco abrem oportunidades para o desenvolvimento novas terapias que procuram regenerar e/ou substituir dentes perdidos ou danificados por diferentes motivos...

This study aimed to conduct a review of the literature on pulp stem cells, undifferentiated cells that have a high capacity for proliferation, self-renewal and differentiation into various cell types and their use in tissue engineering applied to Dentistry. Data sources: The databases used were Pubmed and Bireme. Selection of works: Was performed using the keywords: “Células-tronco mesenquimais”; “Polpa dentária”; “Bioengenharia”. Conclusions: The ability to multipotent differentiation, high rates of proliferation and relatively easy access make the pulp tissue from deciduous and permanent teeth an attractive source of mesenchymal stem cells, which could be used for tissue regeneration. Some studies reported that dental pulp stem cells were capable of producing dental tissues like dentin, pulp and even teeth-like structures in vivo. The progress of stem cell biology research provides opportunities for developing new therapies that seek to regenerate and/ or replace lost or damaged teeth for different reasons...

Perda precoce de molares decíduos em crianças atendidas na Faculdade de Odontologia da Universidade Federal da Bahia / Early loss of deciduous molars in children assisted by the School of Dentistry of the University of Bahia

O objetivo deste estudo foi avaliar a perda precoce de molares decíduos em crianças atendidas na Faculdade de Odontologia da Universidade Federal da Bahia, nos anos de 2010 e 2011. Foram examinados 153 prontuários de crianças entre 03 e 09 anos de idade, onde destas, 35,3% apresentaram perda precoce de molares decíduos, sendo 59,25% do sexo masculino e 40,75% do feminino. A maior frequência de perda precoce de molares decíduos ocorreu em pacientes com nove anos de idade (37%). Quanto à distribuição das perdas em relação ao elemento dentário, observou-se que o segundo molar decíduo inferior esquerdo (75) foi o dente mais acometido, perfazendo um total de 17,1%. Em relação à arcada dentária, as perdas que ocorreram exclusivamente na mandíbula totalizaram 51,9% dos casos, enquanto que 12,9% ocorreram somente na maxila, e, em 35,2% dos prontuários avaliados, as perdas ocorreram em ambas as arcadas. Ressalta-se a fundamental importância de práticas e métodos educativos e preventivos no atendimento às crianças, para que a perda precoce de dentes decíduos seja reduzida, e, quando existente, mantenedores de espaço sejam instalados para prevenir possíveis consequências das perdas prematuras de molares decíduos, como a ocorrência de maloclusões.

The aim of this study was to evaluate the early loss of deciduous molars in children assisted by the School of Dentistry of the Federal University of Bahia (FOUFBA) in the years of 2010 and 2011. Data was collected through the exploration of the medical records of 153 children, between 03 and 09 years old. We found that 35.3% of the records evaluated had early loss of one or more deciduous molars, where 59,25% were males and 40.75% females. The higher frequency of early loss of deciduous molars occurred in patients who are nine years old (37%). The lower left second deciduous molar was the most frequently tooth lost (17.1%). With regard to the arcade, the losses that occurred exclusively in the mandible corresponded to 51.9%, whereas 12,9% occurred only in the maxilla and in 35.2% of the records accessed, the losses occurred in both arches. The results of this study emphasizes the fundamental importance of practices and methods in educational and preventive dental care for children, so that the early loss of deciduous tooth could be reduced, and, if it occurs, space maintainers should be installed to prevent unwanted consequences of premature tooth loss.

Displasia dentinária do tipo I: diferentes aspectos da mesma condição / Dentinal Dysplasia Type I: different aspects of the same condition

A displasia dentinária do tipo I (DD1) é um distúrbio hereditário raro caracterizado pela presença de dentes com esmalte normal e uma dentina atípica. Clinicamente, os dentes apresentam características morfológicas normais, ao passo que, radiograficamente, podem ser observadas raízes curtas e mal formadas. O presente estudo apresenta o caso de duas crianças, ambas com sete anos de idade, onde a DD1 foi diagnosticada, porém, com aspectos clínicos e radiográficos diferentes. O objetivo deste estudo foi apresentar aspectos distintos da mesma condição patológica, tendo em vista que a DD1 pode apresentar uma variabilidade considerável não só de paciente para paciente, mas também de dente para dente em um mesmo indivíduo. No primeiro caso, a queixa principal da paciente era a esfoliação prematura dos dentes, tanto espontaneamente como por trauma menor. Radiograficamente, as raízes apresentavam-se curtas e com um aspecto bastante atípico. Já no segundo caso, verificou-se uma retenção dos dentes permanentes, onde só os primeiros molares estavam presentes na cavidade bucal. Ao exame radiográfico, os dentes não irrompidos apresentavam-se praticamente sem raízes e a polpa dentária bastante obliterada. Os primeiros molares apresentavam taurodontismo. Em ambos os casos, após terem sido realizados os procedimentos preventivos e/ou curativos, um tratamento reabilitador foi planejado.

Dentinal dysplasia type I (DD1) is a rare inherited dentin abnormalitie caractherized by the presence of normal enamel and atypical dentin. Clinically, the teeth have normal morphological caractheristics and radiographically the teeth display defective root formation. This report describes two 7-year-old children that showed characteristic dental features of DD1 with clinical and radiographic differences.

A utilização da técnica da mão-sobre-a-boca (MSB) em odontopediatria: revisão de literatura / The utilization of the hand-over-mouth (HOM) technique in pediatric dentistry: a review of the literature

Esta revisão de literatura tem por objetivo principal trazer à tona aspectos clínicos, éticos e legais relacionados à utilização da técnica de mão-sobre-a-boca(MSB) em Odontopediatria. As principais indicações e contra-indicações, a percepção que os profissionais, pais e/ou responsáveis pelas crianças têm desta manobra e as implicações éticas e legais deste procedimento também são discutidos

Avaliação da indução de VEGF por ácido lipoteicóico em macrófagos e células pulpares / Lipoteichoic acid up-regulates VEGF expression in macrophages and pulp cells

O fator de crescimento vascular endotelial (VEGF) é um potente indutor de angiogênese, permeabilidade vascular e edema. O aumento da expressão de VEGF na polpa dentária pode resultar em pressão intra-pulpar aumentada e contribuir para dor e dano pulpar irreversível. O ácido lipoteicóico (LTA) é uma molécula anfifílica de bactérias gram-positivas que tem sido associada a patogênese da pulpite. Objetivo: Pesquisar se LTA regula a expressão de VEGF em células pulpares ou macrófagos; e avalliar se LT A causa morte celular em células pulpares ou macrófagos. Métodos: Células tipo odontoblasto (MOPC-23), células pulpares indiferenciadas (00-21), fibroblastos gengivais ou macrófagos foram estimulados com 0-80 µg/ml S. sanguis or S. mutans LTA, e a expressão de VEGF foi avaliada por ELlSA e RT-PCR. Foi também realizado o teste de exclusão "Trypan blue", o Teste de Citometria de Fluxo, e a análise do Ciclo Celular, e avaliado se as células morreram por consequência de necrose ou apoptose. As análises estatísticas realizadas foram ANOVA e o "Student t-test" com p' < ou = '0.05. Resultados: LTA induziu um aumento de 9 vezes na expressão proteica de VEGF em macrófagos, um aumento de 2.4 em MOPC-23, de 1.6 em 00-21 quando comparado aos controles. Em contraste, o LTA não induziu a expressão de VEGF em fibroblastos gengivais. A expressão VEGF mRNA permaneceu constante após exposição ao LTA, o que sugere que a regulação de VEGF nessas células é primariamente pós-transcricional. O LTA não causou morte celular significante nas concentrações utilizadas neste trabalho. MDPC-23 foi a única população celular que mostrou um aumento na proporção de células apoptóticas após exposição ao L T A, comparadas com o controle. Conclusão: LTA de streptococci induz elevação de VEGF em macrófagos e células pulpares, e aumento de apoptose em células tipo odontoblasto. Este trabalho constitui a primeira demonstração de que o LTA é suficiente para induzir a expressão de um fator pró-angiogênico.

Vascular endothelial growth factor (VEGF) is a potent inducer of angiogenesis, vascular permeability, and edema. Upregulation of VEGF expression in the dental pulp may result in increased intra-pulpal pressure, and contribute to pain and irreversible tissue damage. Lipoteichoic acid (LTA) is an amphiphilic molecule from Gram-positive bacteria that has been associated with the pathogenesis of pulpitis. Objective: To investigate if LTA regulates expression of VEGF in pulp cells or macrophages; and to evaluate if lTA causes cell death in pulp cells or macrophages. Methods: We stimulated mouse odontoblast-like cells (MDPC-23), undifferentiated pulp cells (OD-21), gingival fibroblasts or macrophages with 0-80 µg/ml S. sanguis or S. mutans LTA, and evaluated VEGF expression by ELlSA and RT -PCR. We also performed Trypan Blue Exclusion Assay, Flow Cytometry Assay, Cell Cycle analyses and evaluated if the cells have died as a consequence of necrosis or apoptosis. Statistical analyses were performed by one-way ANOVA and student t-tests at p' < OR ='0.05. Results: LTA induced up to 9-fold increase in VEGF protein expression in macrophages, 2.4-fold increase in MDPC-23, and 1.6-fold increase in OD-21 as compared to controls. In contrast, L T A did not induce VEGF expression in gingival fibroblasts. VEGF mRNA expression remained constant upon exposure to LTA, which suggests that VEGF regulation in these cells is primarily post-transcriptional. LTA did not cause significant cell death, at the concentrations used here. MDPC-23 was the only cell population that showed an increase in the proportion of apoptotic cells upon exposure to L TA, as compared to controls. Conclusion: Streptococcal LTA induces VEGF upregulation in macrophages and pulp cells, and increase in apoptosis of odontoblast-like cells. This work constitutes the first demonstration that LTA is sufficient to induce expression of a pro-angiogenic factor.