Mechanical-physicochemical properties and biocompatibility of catechin-incorporated adhesive resins.

OBJECTIVES: Several anti-proteolytic dentin therapies are being exhaustively studied in an attempt to reduce dentin bond degradation and improve clinical performance and longevity of adhesive restorations. This study assessed the effect of epigallocatechin-3-gallate (EGCG) on long-term bond strength when incorporated into adhesives. MATERIAL AND METHODS: Adhesive systems were formulated with EGCG concentrations of 0 wt%: (no EGCG; control); 0.5 wt% EGCG; 1.0 wt% EGCG, and 1.5 wt% EGCG. Flexural strength (FS), modulus of elasticity (ME), modulus of resilience (MR), compressive strength (CS), degree of conversion (DC), polymerization shrinkage (PS), percentage of water sorption (%WS), percentage of water solubility (%WL) and cytotoxicity properties were tested. Dentin microtensile bond strength (µTBS) was evaluated after 24 h and again after 6 months of water storage. The adhesive interface was analyzed using scanning electron microscopy (SEM). RESULTS: No significant differences were found among the groups in terms of FS, ME, MR, CS and PS. EGCG-doped adhesives increased the DC relative to the control group. EGCG concentrations of 1.0 wt% and 0.5 wt% decreased the WS of adhesives. WL decreased in all cases in which EGCG was added to adhesives, regardless of the concentration. EGCG concentrations of 1.0 wt% and 0.5 wt% reduced cytotoxicity. EGCG concentrations of 1.0 wt% and 0.5 wt% preserved µTBS after 6 months of storage, while 1.5 wt% EGCG significantly decreased µTBS. SEM: the integrity of the hybrid layer was maintained in the 0.5 wt% and 1.0 wt% EGCG groups. CONCLUSION: EGCG concentrations of 1.0 wt% and 0.5 wt% showed better biological and mechanical performance, preserved bond strength and adhesive interface, and reduced cytotoxicity.

Effects of mineral trioxide aggregate, BiodentineTM and calcium hydroxide on viability, proliferation, migration and differentiation of stem cells from human exfoliated deciduous teeth.

The aim of the study was to evaluate the effects of the capping materials mineral trioxide aggregate (MTA), calcium hydroxide (CH) and BiodentineTM (BD) on stem cells from human exfoliated deciduous teeth (SHED) in vitro. SHED were cultured for 1 - 7 days in medium conditioned by incubation with MTA, BD or CH (1 mg/mL), and tested for viability (MTT assay) and proliferation (SRB assay). Also, the migration of serum-starved SHED towards conditioned media was assayed in companion plates, with 8 µm-pore-sized membranes, for 24 h. Gene expression of dentin matrix protein-1 (DMP-1) was evaluated by reverse-transcription polymerase chain reaction. Regular culture medium with 10% FBS (without conditioning) and culture medium supplemented with 20% FBS were used as controls. MTA, CH and BD conditioned media maintained cell viability and allowed continuous SHED proliferation, with CH conditioned medium causing the highest positive effect on proliferation at the end of the treatment period (compared with BD and MTA) (p<0.05). In contrast, we observed increased SHED migration towards BD and MTA conditioned media (compared with CH) (p<0.05). A greater amount of DMP-1 gene was expressed in MTA group compared with the other groups from day 7 up to day 21. Our results show that the three capping materials are biocompatible, maintain viability and stimulate proliferation, migration and differentiation in a key dental stem cell population.

Effects of mineral trioxide aggregate, BiodentineTM and calcium hydroxide on viability, proliferation, migration and differentiation of stem cells from human exfoliated deciduous teeth

Abstract Objective: The aim of the study was to evaluate the effects of the capping materials mineral trioxide aggregate (MTA), calcium hydroxide (CH) and BiodentineTM (BD) on stem cells from human exfoliated deciduous teeth (SHED) in vitro. Material and Methods: SHED were cultured for 1 - 7 days in medium conditioned by incubation with MTA, BD or CH (1 mg/mL), and tested for viability (MTT assay) and proliferation (SRB assay). Also, the migration of serum-starved SHED towards conditioned media was assayed in companion plates, with 8 μm-pore-sized membranes, for 24 h. Gene expression of dentin matrix protein-1 (DMP-1) was evaluated by reverse-transcription polymerase chain reaction. Regular culture medium with 10% FBS (without conditioning) and culture medium supplemented with 20% FBS were used as controls. Results: MTA, CH and BD conditioned media maintained cell viability and allowed continuous SHED proliferation, with CH conditioned medium causing the highest positive effect on proliferation at the end of the treatment period (compared with BD and MTA) (p<0.05). In contrast, we observed increased SHED migration towards BD and MTA conditioned media (compared with CH) (p<0.05). A greater amount of DMP-1 gene was expressed in MTA group compared with the other groups from day 7 up to day 21. Conclusion: Our results show that the three capping materials are biocompatible, maintain viability and stimulate proliferation, migration and differentiation in a key dental stem cell population.

Graphene oxide/multi-walled carbon nanotubes as nanofeatured scaffolds for the assisted deposition of nanohydroxyapatite: characterization and biological evaluation.

Nanohydroxyapatite (nHAp) is an emergent bioceramic that shows similar chemical and crystallographic properties as the mineral phase present in bone. However, nHAp presents low fracture toughness and tensile strength, limiting its application in bone tissue engineering. Conversely, multi-walled carbon nanotubes (MWCNTs) have been widely used for composite applications due to their excellent mechanical and physicochemical properties, although their hydrophobicity usually impairs some applications. To improve MWCNT wettability, oxygen plasma etching has been applied to promote MWCNT exfoliation and oxidation and to produce graphene oxide (GO) at the end of the tips. Here, we prepared a series of nHAp/MWCNT-GO nanocomposites aimed at producing materials that combine similar bone characteristics (nHAp) with high mechanical strength (MWCNT-GO). After MWCNT production and functionalization to produce MWCNT-GO, ultrasonic irradiation was employed to precipitate nHAp onto the MWCNT-GO scaffolds (at 1-3 wt%). We employed various techniques to characterize the nanocomposites, including transmission electron microscopy (TEM), Raman spectroscopy, thermogravimetry, and gas adsorption (the Brunauer-Emmett-Teller method). We used simulated body fluid to evaluate their bioactivity and human osteoblasts (bone-forming cells) to evaluate cytocompatibility. We also investigated their bactericidal effect against Staphylococcus aureus and Escherichia coli. TEM analysis revealed homogeneous distributions of nHAp crystal grains along the MWCNT-GO surfaces. All nanocomposites were proved to be bioactive, since carbonated nHAp was found after 21 days in simulated body fluid. All nanocomposites showed potential for biomedical applications with no cytotoxicity toward osteoblasts and impressively demonstrated a bactericidal effect without the use of antibiotics. All of the aforementioned properties make these materials very attractive for bone tissue engineering applications, either as a matrix or as a reinforcement material for numerous polymeric nanocomposites.

Zn-doped etch-and-rinse model dentin adhesives: Dentin bond integrity, biocompatibility, and properties.

OBJECTIVE: This study assessed a 6 month resin/dentin bond's durability and cytotoxic effect of Zn-doped model dentin adhesives. The mechanical and physicochemical properties were also tested. METHODS: A model etch-and-rinse single-bottle adhesive was formulated (55wt.% Bis-GMA, 45wt.% HEMA, 0.5wt.% CQ, 0.5wt.% DMAEMA) and Zinc methacrylate (Zn-Mt) or ZnO nanoparticles (ZnOn) were added to the model's adhesive, resulting in three groups: Group Control (control model adhesive); Group Zn-Mt (1wt.% Zn-Mt incorporated to adhesive) and Group ZnOn (1wt.% ZnOn incorporated to adhesive). The microtensile bond strength (mTBS) was assessed after 24h or 6 months in water storage. Mechanical properties (diametral tensile strength/DTS, flexural strength/FS, flexural modulus/FM, resilience modulus/RM, and compressive strength/CS) and physicochemical properties (polymerization shrinkage/PS, contact angle/CA, water sorption/WS, and water solubility/WS) were also tested. Cytotoxicity was evaluated with SRB biochemical assay. RESULTS: No significant difference in the DTS, FS, FM, CS, CA, WS, and WS were found when 1% of ZnOn or Zn-Mt was added to the model dentin adhesive. Group Zn-Mt decreased the RM of adhesive. Groups Zn-Mt and ZnOn decreased the PS of adhesives. Group ZnOn reduced the cytotoxicity of adhesive. Group ZnOn preserved mTBS after 6 months storage without degradation areas as seen by SEM analysis. SIGNIFICANCE: The 1wt.% ZnOn may preserve the integrity of the hybrid layer and may reduce cytotoxicity and polymerization shrinkage of model dentin adhesive. The addition of Zn-Mt to the adhesive had no beneficial effects.

Persistent infection by Staphylococcus epidermidis in endodontic flare-up: a case report.

Endodontic flare-ups are challenging situations and may result from selective growth of specific bacterial species; microbial cultures and antibiograms should be used to allow faster, successful management of refractory lesions. A 47-year-old man reported pain on percussion after uncomplicated retreatment of the maxillary left canine for prosthetic purposes. In the following days, pain dramatically increased, leading to removal of the filling and use of intracanal medication. After many unsuccessful attempts to resolve the problem, a microbial culture of the root canal detected the presence of Staphylococcus epidermidis. An antibiogram determined the best drug combination to control this infection: tetracycline (oxytetracycline hydrochloride, 500 mg orally) plus third-generation cephalosporin (ceftriaxone, 1 g intramuscularly). Once the infection was controlled, the root canal was obturated. There was a reduction in the area of radiolucency, and the patient reported no pain at a 2-year follow-up.

Influence of dental chair backrest inclination on the registration of the mandibular position.

STATEMENT OF PROBLEM: Varying the inclination of the dental chair backrest might alter the distribution of occlusal contact points. PURPOSE: The purpose of this study was to identify the influence of backrest inclination on the registration of the mandibular position. MATERIAL AND METHODS: Ten participants aged between 18 and 30 years with a complete permanent dentition, uncompromised motor function, no tooth mobility, and no temporomandibular disorders were selected. To register interocclusal contacts, an autopolymerizing methylmethacrylate device was adapted to the maxillary anterior teeth and a composite resin increment was added to the mandibular central incisors. Contacts were registered with the following variations in the inclination of the dental chair backrest: 90 degrees, 120 degrees, and 180 degrees. A standardized digital photograph was made of each mark in each backrest position, and the images were superimposed to measure the distances in registration from 90 to 120 and from 90 to 180 degrees. Data were analyzed with the Student paired t test (α=.05). RESULTS: When the chair was inclined from the 90-degree to the 120-degree position, the mandible was repositioned posteriorly by a mean of 0.67 mm, but the difference was not statistically significant. When the chair was inclined from the 90-degree to the 180-degree position, however, the mandible was repositioned posteriorly by a statistically significant mean of 1.41 mm. CONCLUSIONS: Mandibular position is influenced by increasing inclination, and this influence was statistically significant at a 180-degree incline.

In Vitro and in Vivo Studies of Novel Poly(D,L-lactic acid), Superhydrophilic Carbon Nanotubes, and Nanohydroxyapatite Scaffolds for Bone Regeneration.

Poly(D,L-lactide acid, PDLLA) has been researched for scaffolds in bone regeneration. However, its hydrophobocity and smooth surface impedes its interaction with biological fluid and cell adhesion. To alter the surface characteristics, different surface modification techniques have been developed to facilitate biological application. The present study compared two different routes to produce PDLLA/superhydrophilic vertically aligned carbon nanotubes:nanohydroxyapatite (PDLLA/VACNT-O:nHAp) scaffolds. For this, we used electrodeposition and immersion in simulated body fluid (SBF). Characterization by goniometry, scanning electron microscopy, X-ray diffraction, and infrared spectroscopy confirmed the polymer modifications, the in vitro bioactivity, and biomineralization. Differential scanning calorimetry and thermal gravimetric analyses showed that the inclusion of VACNT-O:nHA probably acts as a nucleating agent increasing the crystallization rate in the neat PDLLA without structural alteration. Our results showed the formation of a dense nHAp layer on all scaffolds after 14 days of immersion in SBF solution; the most intense carbonated nHAp peaks observed in the PDLLA/VACNT-O:nHAp samples suggest higher calcium precipitation compared to the PDLLA control. Both cell viability and alkaline phosphatase assays showed favorable results, because no cytotoxic effects were present and all produced scaffolds were able to induce detectable mineralization. Bone defects were used to evaluate the bone regeneration; the confocal Raman and histological results confirmed high potential for bone applications. In vivo study showed that the PDLLA/VACNT-O:nHAp scaffolds mimicked the immature bone and induced bone remodeling. These findings indicate surface improvement and the applicability of this new nanobiomaterial for bone regenerative medicine.

Biocompatibility of two types of resins for prosthetic usage/Biocompatibilidade de dois tipos de resina para uso protético

The purpose of the present study was evaluate the biological compatibility of materials used to manufacture prostheticappliances. A heat-polymerized colorless resin and one visible light-cured denture base material were tested by the implantation of probe discs, in the dorsal connective tissue of 12 Wistar rats. The animals were sacrificed at 7, 14, 21 and 28 days after implantation. The specimens were prepared for light microscopy observation. It was noted that either after light microscopy observations, both resins demonstrated a good level of biocompatibility within the connective tissue of the dorsum of the animals studied.

O objetivo deste trabalho foi avaliar a compatibilidade de biológica de materiais usados na confecção de aparelhosprotéticos. Foram testadas uma resina incolor ativada termicamente e uma resina rosa ativada por luz visível. Discosdestas resinas foram implantados no tecido conjuntivo do dorso de 12 ratos Wistar. Os animais foram sacrificados em 7,14, 21 e 28 dias após a implantação. Os cortes foram preparados para observação em microscopia de luz. Observou-seque as duas resinas demonstraram bom nível de compatibilidade no tecido conjuntivo.

Avaliação de um programa de saúde bucal / Evaluation of an oral health promotion program

O presente trabalho avaliou, utilizando o Índice de Higiene Oral - Simplificado (IHO-S), a efetividade de um programa supervisionado de saúde bucal. Participaram da pesquisa 76 escolares de uma escola municipal de Taubaté - SP, de ambos os sexos, com idade entre 6 a 12 anos. O programa constou da apresentação de palestras, jogos pedagógicos; gincanas e competições, envolvendo as crianças e os professores, abordando hábitos alimentares, higiene bucal, cárie dentária e o uso do flúor. Adicionalmente foram realizadas escovação supervisionada e aplicação de substância evidenciadora de biofilme dentário. Foram realizados três ciclos de atividades, com intervalo de um mês entre cada um deles. Após cada ciclo, foi medido o IHO-S de cada um dos participantes. A análise dos dados obtidos evidenciou diferença significativa na média do IHO-S obtida na primeira, segunda e terceira avaliação, entre o gênero masculino e feminino e diferença significativa na média do IHO-S obtida na primeira, segunda e terceira avaliação, para a primeira, segunda e quarta séries. Foi concluído que o programa proposto no presente estudo mostrou-se efetivo no controle do biofilme dentário e viável para ser aplicado em escolares do primeiro grau

Efeito do estímulo de substâncias liberadas por cimentos endodônticos sobre macrófagos em cultura / Effect of stimulation by substances leached from endodontic sealers on macrophages cells in culture

O selamento biológico dos canais radiculares, almejado pelo tratamento endodôntico, depende não somente dos passos operatórios e substâncias utilizadas nesse processo, mas também do sistema imune do paciente. Portanto, o objetivo desse trabalho in vitro foi analisar a viabilidade de macrófagos previamente ativados com interferon-gama (IFN-g) e lipopolissacarídeos (LPS) e estimulado por substâncias liberadas por 3 cimentos endodônticos. Material e Métodos - Meio de cultura foi condicionado por cimentos comumente utilizados em Endodontia (à base de óxido de zinco e eugenol, resinoso e à base de hidróxido de cálcio) durante 1h ou 24h. Macrófagos foram obtidos de líquido de ascite do peritônio de camundongos e semeados em 42 poços (2 x 105 células/poço) em placas de 96 poços. Após a ativação com IFN-g e LPS de E. coli a mensuração da citotoxicidade de substâncias liberadas dos cimentos foi obtida através do teste de redução do MTT. A absorbância dos poços foi lida em espectrofotômetro usando um filtro de 562 nm. Os dados de seis réplicas foram comparados pelo teste estatístico de Friedman. O nível de significância foi de 5%. Resultados - A viabilidade de células controle e das tratadas pelas substâncias liberadas pelos cimentos foi similar. Os grupos tratados com o cimento de óxido de zinco e eugenol apresentaram diferenças significantes na viabilidade celular. A viabilidade de células de células tratadas com meios condicionados por 1h foi menor do que o daquela de células tratadas com meio condicionado por 24h. Conclusão - Independentemente do tempo de condicionamento (1h ou 24h) as substâncias liberadas durante a presa dos cimentos endodônticos testados não foram citotóxicas aos macrófagos peritoniais de camundongos ativados e em cultura

[Ethics in the authorship of scientific papers]. / Etica em autoria de trabalhos científicos.

This article stresses the importance of ethical relations involved in intellectual production, particularly as regards quantity, quality, authorship and publication. It reaffirms the importance of ethics while managing workgroups, and the effective participation in the development of experimental projects.

Ética em autoria de trabalhos científicos / Ethics in the authorship of scientific papers

O texto alerta para a consciência da relação ética da produção intelectual no que refere a quantidade, qualidade, autoria e publicação. Reafirma a importância da questão ética do gerenciamento de grupos de trabalho e a efetiva participação no desenvolvimento do projeto experimental

Avaliação do desgaste de pontas diamantadas e sua influência na infiltração marginal de restaurações de resina composta / Evaluation of diamond burs grinding and its influence on microleakage of composite restorations

Avaliou-se neste estudo o desgaste de pontas diamantadas utilizadas em preparos cavitários e sua influência na microinfiltração de restaurações em resina composta. Para tanto, cinquenta incisivos bovinos e dez pontas diamantadas (KG Sorensen) foram utilizados. Para simular o desgaste das pontas foram empregados vinte dentes, descartados após utilização. Os trinta dentes remanescentes foram divididos em três grupos (n=10), de acordo com a quantidade de vezes que a ponta foi utilizada para a realização de preparos de classe V na face vestibular: Grupo I - preparos cavitários realizados com pontas novas (Controle); Grupo II - pontas utilizadas cinco vezes; Grupo III - pontas utilizadas dez vezes. As cavidades foram restauradas com Prime & Bond 2.1/TPH (Dentsply). Os dentes foram termociclados (500 ciclos - 5°C e 55°C), armazenados em corante Rodhamina B a 2 por cento por 24 h e seccionados no sentido vestíbulo-lingual. Os espécimes foram avaliados quanto à microinfiltração marginal em estereomicroscópio. As pontas diamantadas foram analisadas também em estereomicroscópio para avaliar o desgaste, antes de serem utilizadas e após o primeiro, quinto e décimo preparo cavitários. Para ambas as avaliações foram atribuídos escores, sendo os dados da microinfiltração submetidos ao teste de Kruskal-Wallis (a=0,05), não mostrando diferença significante entre os grupos. Os resultados do desgaste das pontas foram analisados pelo teste de Kruskal-Wallis e teste de Dunn para comparações múltiplas (a=0,05), evidenciando diferença significante entre as pontas novas e as utilizadas no quinto e décimo preparos. Embora as pontas diamantadas tenham exibido desgaste com o uso, não houve influência estatisticamente significante na infiltração marginal das restaurações

Resposta de fibroblastos de polpa humanos frente a substâncias liberadas por capeadores pulpares diretos / Human pulp fibroblasts response to substances leached from direct pulp capping materials

O objetivo do presente estudo foi o de avaliar os efeitos citotóxicos de substâncias liberadas durante a aplicação de materiais utilizados em capeamento pulpar direto, sobre fibroblastos de polpa dentária humana. Utilizou-se para o experimento meios condicionados pelas substâncias a serem testadas, divididas nos grupos a seguir: grupo I: controle (meio de cultivo sem condicionamento); grupo II: cimento de hidróxido de cálcio; grupo III: adesivo dentinário; grupo IV: ácido ortofosfórico a 37 por cento. O condicionamento foi realizado, colocando-se meio de cultivo fresco sobre os materiais de modo que a presa (grupo II), polimerização (grupo III) ou o contato direto (grupo IV) liberassem substâncias para esse meio de cultivo. Esse meio era colocado sobre as células durante todo o experimento, excetuando-se o grupo IV, onde o contato foi feito por um período de 15 segundos, conforme recomendações clínicas. Posteriormente foram realizadas contagens em hemocitômetro pelo método de exclusão por azul de Trypan, que cora somente as células mortas. As contagens foram realizadas em períodos de 0, 6, 12 e 24 horas para o experimento de viabilidade celular (curto prazo), onde se avaliou o percentual de células vivas sobre o total de células, e em períodos de 1, 3, 5 e 7 dias para o experimento de sobrevivência celular, no qual se avaliou o número absoluto de células vivas. Observou-se que as substâncias liberadas pelo adesivo dentinário são citotóxicas em qualquer período, diminuindo consideravelmente a viabilidade celular e afetando suas curvas de crescimento. Aquelas liberadas pelo ácido ortofosfórico a 37 por cento provocam diminuição da viabilidade somente nos primeiros momentos do contato com as células, enquanto as substâncias liberadas durante a presa do hidróxido de cálcio não são citotóxicas em nenhum momento