RESUMO
The aim of this study was to develop a mixture of dimethacrylate isomers (PG6EMA) as a potential monomer for dental adhesives and composites. PG6EMA was synthesized de novo and characterized in the presence of ethanol (3%, 6% or 9%). BisGMA/TEGDMA (BTEG, 50/50 wt.%) was used as the resin control. Composites were formulated with 60 wt.% of either PG6EMA or BisGMA (40 wt.% TEGDMA and 70 wt.% filler). DMPA (0.2 wt.%) and DPI-PF6 (0.4 wt.%) were added as photoinitiators, irradiated with a mercury arc lamp (320-500 nm, 500 mW/cm2; Acticure). All materials were tested for polymerization kinetics (near-infrared), viscosity (η) and storage modulus (G', oscillatory rheometry). The composites were further characterized for water sorption/solubility, wet/dry flexural strength/modulus and polymerization stress. Data were analyzed with one-way ANOVA/Tukey's test (α = 0.05). The PG6EMA resins showed lower rates of polymerization compared with BTEG (p = 0.001) but high degrees of conversion (p = 0.002). Solvent concentration did not affect RPMAX but the 6% and 9% mixtures showed higher final DC, likely due to reduced viscosity. PG6EMA had much higher viscosity than BTEG (p <0.001) and lower G' (p = 0.003). Composites modified with PG6EMA have slower polymerization rates (p = 0.001) but higher final DC (p = 0.04) than the control. PG6EMA/TEGDMA showed lower dry/wet flexural strength and comparable dry modulus. The PG6EMA/TEGDMA composite showed a 18.4% polymerization stress reduction compared to the BTEG composite. Both base monomers had similar WS/SL and G'. Within its limitations, this study demonstrated that the newly synthesized PG6EMA was a viable alternative to BisGMA in dental composites.
Assuntos
Bis-Fenol A-Glicidil Metacrilato , Resinas Compostas , Teste de Materiais , Metacrilatos , Polimerização , Ácidos Polimetacrílicos , Resinas Compostas/química , Resinas Compostas/efeitos da radiação , Bis-Fenol A-Glicidil Metacrilato/química , Metacrilatos/química , Viscosidade , Ácidos Polimetacrílicos/química , Análise de Variância , Fatores de Tempo , Reprodutibilidade dos Testes , Valores de Referência , Resistência à Flexão , Polietilenoglicóis/química , Propriedades de Superfície , Solubilidade , Cinética , Reologia , Cimentos Dentários/química , Cura Luminosa de Adesivos Dentários/métodosRESUMO
Objetivo: O objetivo foi avaliar a resistência de união de seis adesivos experimentais contendo sistemas fotoiniciadores binários ou ternários, associados a três diferentes concentrações de MDP (0-12% em peso) após 12 meses de armazenamento em água destilada. Material e Métodos: Adesivos experimentais foram preparados com: bis-GMA, UDMA, bis-EMA, TEGDMA, HEMA, BHT e etanol, contendo sistemas fotoiniciadores binários (CQ/amina) ou ternários (CQ/amina/DPIHFP 0,5% em peso). Foi adicionado a esta composição 0%, 6% ou 12% em peso de MDP. Os sistemas adesivos foram aplicados seguindo o protocolo com condicionamento ácido. Moldes cilíndricos transparentes foram colocados sobre a dentina hibridizada, preenchidos com resina composta e fotopolimerizados. Os corpos-de-prova foram armazenados em água destilada a 37oC por 24h ou 12 meses e submetidos ao ensaio de microcisalhamento (n=6). Os dados foram analisados por ANOVA de três fatores e teste de Tukey (α=5%). Resultados: Para o sistema binário, após 12 meses de armazenamento, todos os valores de resistência de união foram semelhantes. Em relação à degradação da resistência de adesão ao longo do tempo, as formulações de MDP de 6% e 12% mostraram resistência de união mais estável do que 0% de MDP. Para o sistema ternário, todas as formulações (0%, 6% e 12% em massa de MDP) mostraram resistência de união estável em função do tempo. Conclusão: Para o sistema binário, as concentrações de 6 e 12% em massa de MDP foram capazes de manter a resistência de união em função do tempo, enquanto que para o sistema ternário, a estabilidade de união foi obtida independentemente da concentração de MDP. Pode-se concluir que, para a formulação dos adesivos utilizados neste estudo, independente do sistema fotoiniciador, a concentração de 12% MDP apresentou valores de resistência de união mais estáveis após 12 meses de armazenamento em água (AU)
Objective: The aim was to evaluate the bond strength of six experimental adhesives containing binary or ternary photoinitiator systems, associated with three different MDP concentrations (0-12wt%) after 12 months of storage in distilled water. Material and Methods: Experimental adhesives were prepared with: bis-GMA, UDMA, bis-EMA, TEGDMA, HEMA, BHT, and ethanol, containing binary (CQ/amine) or ternary (CQ/amine/DPIHFP (diphenyliodonium hexafluorophosphate) 0.5wt%) photoinitiator systems. It was added to this composition 0wt%, 6wt%, or 12wt% of MDP. The adhesive systems were applied following the etch-and-rinse protocol. Transparent cylindrical molds were placed on the hybridized dentin, filled with composite resin and light-cured. The specimens were stored in distilled water at 37oC for 24h or 12 months and submitted to a microshear bond strength test (n=6). Data were analyzed by three-way ANOVA and Tukey's test (α=5%). Results: For the binary system, after 12 months of storage, all bond strength values were similar. Regarding bond strength degradation over time, 6wt% and 12wt% MDP formulations showed more stable bond strength than 0wt% MDP. For the ternary system, all formulations (0wt%, 6wt% and 12wt%) showed stable bond strength over time. Conclusion: For the binary photoinitiator system, the 6wt% and 12wt% MDP concentrations were able to keep bond strength stable over time, while for the ternary system, bond strength stability was achieved regardless the MDP concentration. (AU)
Assuntos
Cimentos Dentários , Fotoiniciadores DentáriosRESUMO
The aim of this research was to evaluate the influence of MDP (10-methacryloyloxydecyl dihydrogen phosphate) concentration and application mode of experimental adhesives on microshear bond strength (µSBS) to dentin after storage in distilled water at 37°C for 24h and 6 months. Five experimental adhesives were prepared with: CQ, DABE, BHT, ethanol, HEMA, TEGDMA, Bis-EMA, UDMA, and Bis-GMA. Concentrations of 0 wt%, 3 wt%, 9 wt%, 12 wt% or 15 wt% of MDP were added to their composition. The adhesives were applied to flat dentin surfaces in etch-and-rinse or self-etching modes. Cylindrical molds filled with light-cured composite resin were placed above the dentin. The specimens were stored in distilled water at 37oC for 24h or 6 months and submitted to µSBS testing. The adhesives were also submitted to pH analysis. The data were analyzed by one-way ANOVA, three-way ANOVA and Tukey's test (α = 5%). All the adhesives used in the etch-and-rinse mode showed significantly higher bond strength than the adhesives applied in the self-etching approach. The 9 wt% adhesive showed the highest bond strength values, and 3 wt% was most stable after storage. A strong negative correlation between MDP concentration and pH was observed. It was concluded that the formulations with low concentrations of MDP (up to 9 wt%) showed better results for bond strength and bond strength degradation over time.
Assuntos
Colagem Dentária , Adesividade , Resinas Compostas , Cimentos Dentários , Dentina , Adesivos Dentinários , Teste de Materiais , Cimentos de Resina , Resistência à TraçãoRESUMO
The objective of this case report was to present the orthodontic treatment of an 8-year-old female patient with Fanconi's anemia and Class III skeletal pattern and agenesis of maxillary lateral incisors. Patient presented in the late mixed dentition with a Class III malocclusion with anterior and posterior crossbites. Rapid maxillary expansion and facemask therapy was performed for 12 months. Phase II was simplified with a 6 × 2 fixed appliance only in the mandibular arch for solving the anterior crowding. Maxillary canines were reshaped as lateral incisors and the central incisors were augmented for closing spaces. Although the systemic disease, orthodontic intervention is possible if individual limitations are considered and treatment is simplified.
Assuntos
Anemia de Fanconi , Má Oclusão Classe III de Angle , Má Oclusão , Cefalometria , Criança , Feminino , Humanos , Incisivo , Maxila , Técnica de Expansão PalatinaRESUMO
Abstract The aim of this research was to evaluate the influence of MDP (10-methacryloyloxydecyl dihydrogen phosphate) concentration and application mode of experimental adhesives on microshear bond strength (μSBS) to dentin after storage in distilled water at 37°C for 24h and 6 months. Five experimental adhesives were prepared with: CQ, DABE, BHT, ethanol, HEMA, TEGDMA, Bis-EMA, UDMA, and Bis-GMA. Concentrations of 0 wt%, 3 wt%, 9 wt%, 12 wt% or 15 wt% of MDP were added to their composition. The adhesives were applied to flat dentin surfaces in etch-and-rinse or self-etching modes. Cylindrical molds filled with light-cured composite resin were placed above the dentin. The specimens were stored in distilled water at 37oC for 24h or 6 months and submitted to μSBS testing. The adhesives were also submitted to pH analysis. The data were analyzed by one-way ANOVA, three-way ANOVA and Tukey's test (α = 5%). All the adhesives used in the etch-and-rinse mode showed significantly higher bond strength than the adhesives applied in the self-etching approach. The 9 wt% adhesive showed the highest bond strength values, and 3 wt% was most stable after storage. A strong negative correlation between MDP concentration and pH was observed. It was concluded that the formulations with low concentrations of MDP (up to 9 wt%) showed better results for bond strength and bond strength degradation over time.
Assuntos
Colagem Dentária , Resistência à Tração , Teste de Materiais , Adesividade , Adesivos Dentinários , Resinas Compostas , Cimentos de Resina , Cimentos Dentários , DentinaRESUMO
Endocrowns são coroas confeccionadas utilizando a câmara pulpar como recurso mecânico de retenção, evitando a necessidade de pinos e preparos mais extensos. Essas restaurações podem ser confeccionadas através de diferentes técnicas, dentre elas, a técnica semidireta. Esta técnica consiste na confecção de restauração extrabucal de resina composta, geralmente em modelos rígidos ou flexíveis, e posterior cimentação, sendo uma alternativa que facilita a reprodução anatômica, acabamento e polimento da restauração e menor custo para o paciente. O objetivo deste trabalho é relatar um caso clínico de paciente com molar extensamente destruído e tratado endodonticamente, em que uma restauração do tipo Endocrown foi confeccionada através de técnica semidireta. Neste caso, o dente 46 de um paciente do gênero masculino, de 33 anos, foi preparado com pontas diamantadas tronco-cônicas, de modo a se obter um preparo ligeiramente expulsivo, este foi moldado com silicona de condensação. Ao molde, foi injetada silicona de adição para obtenção de um modelo flexível para a confecção da restauração. Posteriormente, a restauração foi realizada neste modelo, utilizando-se resina Bulk Fill para preenchimento da cavidade, seguida de dentina A3, aplicação de pigmento ocre e camada de resina de esmalte A2 e, após fotopolimerização, a peça foi cimentada com cimento resinoso. Os procedimentos de acabamento e polimento foram realizados fora da boca e também foi realizado procedimento de pós-polimerização para obtenção de melhores propriedades mecânicas da restauração. A restauração semidireta do tipo Endocrown devolveu função e estética ao molar, com adequada adaptação marginal, garantindo resultados imediatos, baixo custo e conforto ao paciente (AU).
Endocrowns are restorations performed using the pulp chamber for mechanical retention, avoiding more extensive preparations and the need of posts and pins. These restorations can be made through different techniques, among them, the semidirect technique. This technique consists in the preparation of an extraoral restoration of composite resin, usually in rigid or flexible dies followed by cementation, which is an alternative that facilitates the anatomical reproduction, finishing and polishing of the restoration, and lower cost for the patient. The purpose of this paper is to report a clinical case of a patient with extensively destroyed and endodontically treated molars, in which an Endocrown restoration was performed using a semidirect technique. In this case, the tooth 46 of a 33-year-old male patient was prepared with cone-shaped diamond tips in order to obtain a slightly expulsive preparation, the impression was made with condensation silicone, and the flexible die was obtained through addition silicone. Subsequentely, the restoration was performed in this die, using a Bulk Fill resin composite, followed by dentin A3, application of ocher pigment and enamel A2 resin layer and, after photopolymerization, the resin Endocrown was cemented with resin cement. The finishing and polishing procedures were performed outside the mouth and a post-polymerization procedure was also performed to obtain better mechanical properties of the restoration. The semidirect restoration of the Endocrown replaced function and aesthetics to the molar, with adequate marginal adaptation, guaranteeing immediate results, low cost and comfort to the patient (AU).
Assuntos
Humanos , Masculino , Adulto , Resinas Compostas , Restauração Dentária Permanente , Endodontia , Polimerização , Brasil , Radiografia Dentária/instrumentaçãoRESUMO
Objective: The topical fluoride application is the main strategy to remineralize white spots lesions (WSL). It is assumed that increasing its retention in the surface can favor remineralization. Therefore, previous treatments of the enamel surface are purposed to optimize its efficacy. This study aimed to evaluate the remineralization capacity of the fluoride without and with the pre-treatment of the enamel with phosphoric acid and aluminum nitrate and then, the enamel acid-resistance after new acid challenge. Material and Methods: Twenty-four enamel bovine blocks were obtained and selected by means of initial surface microhardness (SMH) measurements. In sequence, WSL were artificially inducted by DE-RE cycling and randomized in two groups according to the enamel pretreatment to be tested (n=12): F (1.23% fluoride gel - APF- 4min) and P-Al-F (37% phosphoric acid- 30s + 0.05M aluminum nitrate 1min + APF- 4min). After then, a new acid challenge was equally performed. Additional SMH assessments were performed in each step. The values were processed and the percentage of SH loss (%SHL) was obtained. Data were statically analyzed by two-way ANOVA and Tukey tests (p <0.05). Results: There was no difference between evaluated protocols. For both groups, a significant difference among the steps of study was detected: it was observed a decrease of %SHL after the treatment and increase of %SHL after the new acid challenge. Conclusion: Enamel pretreatment with phosphoric acid associated with aluminum nitrate promoted similar protective effect compared to fluoride itself on the remineralization of artificial WSL, partially recovering the surface hardness. After new challenge, they also offered partial resistance. (AU)
Objetivos: A aplicação tópica de flúor é a principal estratégia para remineralizar lesões de mancha branca (MB). Foi proposto que o aumento na retenção deste íon na superfície pode favorecer a remineralização. Portanto, o tratamento prévio da superfície do esmalte foi proposto para otimizar sua eficácia. Material e Métodos: Este estudo objetivou avaliar a capacidade de remineralização do fluoreto com e sem pré-tratamento do esmalte com ácido fosfórico e nitrato de alumínio e a resistência do esmalte após novo desafio ácido. Vinte e quatro blocos de esmalte bovino foram obtidos e selecionados pela média inicial de microdureza de superfície (MS). Em seguida, MB foram artificialmente induzidas através de ciclagem DES-RE e os espécimes aleatorizados em dois grupos de acordo com o pré-tratamento do esmalte a ser avaliado (n=12): F (flúor gel acidulado 1,23% - APF - 4 min) e P-Al-F (ácido fosfórico 37% - 30s + nitrato de alumínio 0,05M 1min + APF por 4 min). Após o tratamento, um novo desafio ácido semelhante ao inicial foi realizado. Novas avaliações de MS foram obtidas em cada etapa. Os valores foram processados e a porcentagem de perda mineral da superfície (%PDS) foi obtida. Os dados foram analisados estatisticamente por ANOVA dois critérios e teste de Tukey (p <0,05). Resultados: Não houveram diferenças entre os protocolos avaliados. Para ambos grupos, uma diferença significante entre as fases do estudo foi detectada: observouse uma queda no %PDS após o tratamento e aumento do %PDS após novo desafio ácido. Conclusão: O pré-tratamento do esmalte com ácido fosfórico associado com nitrato de alumínio promoveu efeito similar à aplicação isolada do APF na remineralização das MB artificiais, recuperando parcialmente a dureza de superfície. Após o novo desafio ácido, os dois grupos ofereceram resistência parcial. (AU)
Assuntos
Cárie Dentária , Esmalte Dentário , Fluoretos , Flúor , Remineralização DentáriaRESUMO
O objetivo deste estudo in vitro foi avaliar a biocompatibilidade de uma zircônia tetragonal policristalina estabilizada por ítrio (Y-TZP), um cimento à base de resina (RelyX ™ Ultimate) e um adesivo à base de 10-MDP (Single Bond Universal) modificados ou não por nanotubos de titânio (TiO2), por meio dos testes de viabilidade celular MTT e Cristal Violeta. Para este fim, foram obtidos discos de 13 mm x 2 mm de zircônia Y-TZP (IPS e.max ZirCAD). Os discos de cimento resinoso e adesivo com 10-MDP foram obtidos através de um molde metálico com as mesmas dimensões. Para Y-TZP, a incorporação de nanotubos de TiO2 ocorreu antes da sinterização, enquanto para os materiais à base de resina, 0,3% em peso de nanotubos foram adicionados antes da fotopolimerização. Os espécimes foram divididos em 8 grupos (n = 8). A avaliação in vitro foi feita através de testes nos quais as células da linhagem de fibroblastos NIH 3T3 foram colocadas em contato indireto com estes materiais. Para a viabilidade celular foram realizados MTT e Cristal Violeta em duplicata e após 24, 48 e 72 horas a absorbância foi analisada por espectrofotometria em leitora Elisa. Os dados obtidos foram submetidos a ANOVA a dois critérios, seguido do teste de Tukey (α = 0,05). Os resultados mostraram que em 24 e 48 hs todos os materiais mostraram-se biocompatíveis. No período de 72 hs os maiores aumentos de absorbância aconteceram para os grupos Y-TZP sem nanotubos de TiO2 e adesivo com nanotubos de TiO2 comparados aos demais grupos. De modo geral, a incorporação de nanotubos a estes materiais não interferiu na viabilidade celular em ambos os testes.(AU)
The aim of this in vitro study was to evaluate the biocompatibility of yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP), a resin-based cement (RelyX™ Ultimate) and a 10- MDP-based adhesive (Single Bond Universal) modified or not by titanium nanotubes (TiO2), by means of the MTT cell viability test and Crystal Violet. For this purpose, disks of 13 mm in diameter per 2 mm is thickness of pre-sintered Y-TZP zirconia (IPS e.max ZirCAD) were obtained. The resin-cement and a 10-MDP adhesive disks were obtained through a metal mold with the same dimensions. For Y-TZP, the incorporation of TiO2 nanotubes occured before sinterization, while for the resin-based materials 0.3wt% of nanotubes were added to the uncured materials. The specimens were divided into 8 groups (n = 8). The in vitro evaluation was carried out by means of tests in which fibroblast line NIH 3T3 cells were placed into indirect contact with these materials. For cell viability were made MTT assay tests and Crystal Violet in duplicate and after 24, 48 and 72 hours the absorbance levels were analyzed by spectrophotometry Elisa reader. The data obtained were submitted to two-way ANOVA, followed by Tukey test (α = 0.05). In the period of 72 the highest increases of absorbance happened for the groups Y-TZP without TiO2 nanotubes and adhesive with TiO2 nanotubes when compared to the other groups. In general, the incorporation of nanotubes into these materials did not interfere with cell viability in both tests.(AU)