Influência da utilização de ácido glicólico e adesivos universais na qualidade da camada híbrida em restaurações adesivas: revisão de literatura / Influence of the use of glycolic acid and universal adhesives on the quality of the hybrid layer in adhesive restorations: literature review

A camada híbrida é definida pela zona de inter difusão do polímero do adesivo e o substrato dental. Os sistemas adesivos universais são materiais que foram criados com o intuito de substituir a estrutura dental que foi perdida a fim de diminuir essa área de interação adesiva e os espaços desmineralizados da dentina. O objetivo do seguinte estudo é realizar uma revisão de literatura acerca da influência dos adesivos universais e o uso do ácido glicólico como condicionante dental. Foi realizada uma busca na literatura atual, nas seguintes bases de dados: PubMed, Scielo, Medline e Google Acadêmico nos idiomas inglês e português usando os termos de pesquisa: "adhesive systems" AND "phosphoricacid" OR/AND "glycolicacid" OR/AND "hybridlayer" OR/AND "universal adhesive system". As pesquisas realizadas utilizando o ácido glicólico como agente condicionante dental demonstraram que a substância tem potencial e efetividade, diminuindo consideravelmente a região de fibras colágenas expostas para a fusão do adesivo universal. O ácido glicólico utilizado como agente condicionante de esmalte e dentina mostrou-se eficaz e promissor, tendo em vista que a camada híbrida se apresentou com menor espessura sem alterar a estrutura dentinária. Porém, faz-se necessário mais pesquisas utilizando o ácido glicólico juntamente com o sistema adesivo universal, por curto, médio e longo prazo.

The hybrid layeri s defined by the interdiffusion zone of the adhesive polymer and the dental substrate. Universal adhesive systems are materials that have been created with the aim of replacing the tooth structure that has been lost in order to reduce this area of adhesive interaction and the demineralized spaces of dentin. The aim of the following study is to perform a literature review on the influence of universal adhesives and the use of glycolic acid as a dental conditioning agent. A search was conducted in the current literature in the following databases: PubMed, Scielo, Medline and Google Scholar in English and Portuguese using the search terms: "adhesive systems" AND "phosphoric acid" AND "glycolic acid" AND "hybrid layer" OR "universal adhesive system". Research using glycolic acid as a dental conditioning agent has shown that the substance has potential and effectiveness, considerably reducing the region of collagen fibers exposed for the fusion of the universal adhesive. Glycolic acid used as a conditioning agent for enameland dent inproved to be effective and promising, considering that the hybrid layer was presented with less thickness without altering the dentin structure. However, further research his needed usinggly colic acid together with the universal adhesive system, for short, medium and long term.

Mechanical, optical, and physicochemical properties of HPMC-based doxazosin mesylate orodispersible films

Abstract In this study, orodispersible films formed from hydroxypropyl methylcellulose (HPMC) E6 (2, 2.5, and 3%) and plasticizers ((glycerin (Gly), propylene glycol (PP), or polyethylene glycol (PEG)), containing doxazosin mesylate, were prepared by the solvent casting method and characterized. Design of experiments (DoE) was used as a statistical tool to facilitate the interpretation of the experimental data and allow the identification of optimal levels of factors for maximum formulation performance. Differential scanning calorimetry (DSC) curves and X-ray powder diffraction (XRPD) diffractograms showed doxazosin mesylate amorphization, probably due to complexation with the polymer (HPMC E6), and the glass transition temperature of the polymer was reduced by adding a plasticizer. Fourier transformed infrared (FTIR) spectroscopy results showed that the chemical structure of doxazosin mesylate was preserved when introduced into the polymer matrix, and the plasticizers, glycerin and PEG, affected the polymer matrix with high intensity. The addition of plasticizers increased the elongation at break and adhesiveness (Gly > PEG > PP), confirming the greater plasticizer effect of Gly observed in DSC and FTIR studies. Greater transparency was observed for the orodispersible films prepared using PP. The addition of citric acid as a pH modifier was fundamental for the release of doxazosin mesylate, and the desirability formulation had a release profile similar to that of the reference product

Bond strength of bulk fill composite to teeth prepared with Er: YAG laser

Aim: The present in vitro study aimed to evaluate the bond strength of a bulk fill composite on dentin surfaces prepared with the Er: YAG laser. Methods: Twenty-four permanent third molars were selected and divided into 2 groups: CP - Conventional preparation with high-speed handpiece (control) and LA (laser) - Preparation with Er: YAG laser. The occlusal surface was removed to expose coronal dentin, which was subsequently prepared with a high-speed handpiece or Er: YAG laser (350mJ, 4Hz, 1.5 ml/min water flow). Both groups were restored with Filtek One Bulk Fill (3M ESPE) composite resin. After 24 hours, the samples were evaluated for microtensile bond strength (µTBS), fracture pattern, and scanning electron microscopy (SEM). Results: The data obtained in the µTBS test were submitted to t-test (α=0.05). The results showed no difference in µTBS when the different types of cavity preparation were compared (ρ=0.091). Fracture patterns revealed the prevalence of cohesive fracture in composite resin in CP (83.3%) and adhesive fracture in LA (92.1%). In the SEM analysis, the LA group demonstrated the presence of gaps between the composite resin and the irradiated dentin surface. The hybrid layer exhibited more regularity with the presence of longer and uniform resin tags in the CP group. Conclusion: The type of cavity preparation did not influence the values of bulk fill composite resin µTBS to dentin. Fracture patterns and scanning electron microscopy analyses suggested less interference at the adhesive interface in preparations performed using CP

A comparative physicochemical and pharmacological evaluation of dexamethasone sodium phosphate and betamethasone sodium phosphate mucoadhesive gels for the treatment of oral submucous fibrosis in rats

Abstract The present study is aimed to formulate steroidal oral mucoadhesive gels of dexamethasone sodium phosphate and betamethasone sodium phosphate. Six gel formulations each of dexamethasone sodium phosphate and betamethasone sodium phosphate prepared using two different polymers carboxymethyl cellulose sodium and hydroxypropyl methylcellulose, in variable proportions. All the formulations subjected for assessment of various physicochemical parameters and mechanical properties. The formulations BSP5 and DSP5, both containing 1.25 % carboxymethyl cellulose sodium, 1.25 % hydroxypropyl methylcellulose, exhibiting mucoadhesive strength of 12.300 ± 0.004 and 12.600 ± 0.01, adhesiveness of 28.04 ± 00 and 30.02 ± 00, cohesiveness of 28.04 ± 00 and 30.02 ± 00, drug release of 86.869 ± 0.380 % and 88.473 ± 0.457 % respectively were considered as promising ones and were further subjected for stability studies and in vivo study in male albino rats. Formulation DSP5 upon oral application for 4 months in arecoline induced oral submucous fibrosis rats, showed more than 80 % reduction in fibrosis as compared with BSP5 which showed nearly 50 % reduction. These results were concluded on the basis of histopathological profile and weight gain among the experimental animals during in vivo study. Hence, DSP5 by minimizing the painful injuries and morbidities justifies being suitable noninvasive model for OSMF treatment.

Esthetic rehabilitation with indirect resin on anterior teeth: a clinical report / Reabilitação estética com resina indireta em dentes anteriores: um relato clínico / Rehabilitaciónestética con resina indirecta en dientes anteriores: reporte clínico

Introduction:The aesthetic rehabilitation of endodontically treated teeth depends on the destruction degree of the crown, the bone support, type of prosthesis, andchewing forces. In these cases, indirect restorations with composite resins are an excellent alternative. The indirect composite resins have improved physical and mechanical properties due toincorporatingof inorganic fillersand multifunctional monomers. These components offer a greater bonding strength to the indirect restorations, which is advantageous for further rehabilitations with ceramic crowns. Objective:To present an aesthetic rehabilitation of anterior teeth with indirect composite resin as a feasible and less expensive treatment alternative.Case Report:Upon clinical examination, extensive and deficient restorations were observed in the upper anterior teeth. The proposed treatment plan was the aesthetic rehabilitation of endodontically treated teeth with indirect restorations using ceromer.Conclusions:This treatment represented an excellent alternative for aesthetic rehabilitation of endodontically treated teeth in cases of great dental crown destruction or small dental absences (AU).

Introdução:A reabilitação estética de dentes tratados endodonticamente depende do grau de destruição da coroa, do dente em questão, do suporte ósseo, do tipo de prótese e dos tipos de forças a que esses dentes serão submetidos. As resinas compostas indiretas apresentam propriedades físicas e mecânicas aprimoradas graças à incorporação de componentes inorgânicos e monômeros multifuncionais com maior número de pontos de união, tornando-os capazes de solucionar os problemas em que seriam indicadas restaurações cerâmicas. Objetivo:Apresentar um relato de caso clínico de uma reabilitação estética de dentes anteriores com resina composta indireta como alternativa de tratamento viável e de menor custo.Relato de Caso:Ao exame clínico foram observadas restaurações amplas e deficientes nos dentes anteriores superiores. O plano de tratamento proposto reabilitação estética dos elementos dentários com cerômeros.Conclusões:Este tratamento representou uma opção viável e demenor custo que pode ser utilizado tanto em situações de grande destruição dentária como em pequenas ausências dentárias, em substituição às restaurações de cerâmica (AU).

Introducción: La rehabilitación estética de los dientes tratados endodónticamente depende del grado de destrucción de la corona, el diente en cuestión, el soporte óseo, el tipo de prótesis y los tipos de fuerzas a las que estos dientes serán sometidos. Las resinas compuestas indirectas tienen propiedades físicas y mecánicas mejoradas gracias a la incorporación de componentes inorgánicos y monómeros multifuncionales con mayor número de puntos de unión, lo que las hace capaces de resolver los problemas en los que estarían indicadas las restauraciones cerámicas. Objetivo: Presentar un caso clínico de rehabilitación estética de dientes anteriores con resina compuesta indirecta como alternativa de tratamiento viable y menos costosa. Reporte de Caso:En el examen clínico, se observaron restauraciones extensas y deficientes en los dientes anteriores superiores. El plan de tratamiento propuesto para la rehabilitación estética de elementos dentales con cerómeros. Conclusiones:Este tratamiento representó una opción viable y menos costosa que se puede utilizar tanto en situaciones de gran destrucción dentaria como en pequeñas ausencias dentales, en sustitución de las restauraciones cerámicas (AU).

Estudo in vitro da influência de diferentes plugs coronários sobre o remanescente da obturação, após preparo para pino, na retenção de pinos metálicos fundidos / In vitro assessment of the influence of different protection plugs over obturation remnant space, after post preparation, on the retention of cast metal posts

Objetivo: Avaliar a influência de diferentes plugs de proteção, acomodados sobre o remanescente da obturação após preparo para pino, na retenção de pinos metálicos fundidos. Métodos: Cinquenta dentes bovinos foram decoronados, manualmente instrumentados até a lima manual Kerr #80 e obturados. A desobturação parcial de 10mm do conduto foi realizada com uma broca Largo e os grupos foram divididos de acordo com os diferentes materiais utilizados como plugs (n=10): Grupo I (Controle, sem plug); Grupo II (plug de Coltosol®); Grupo III (plug, em consistência de massa, de Sealapex® + óxido de zinco); Grupo IV (plug de etil-cianoacrilato); e Grupo V (plug de fosfato de zinco). Uma camada de 1mm de espessura dos diferentes plugs (Grupos II, III, IV ou V) foi acomodada sobre a obturação remanescente. Os espécimes foram selados e armazenados em 100% de umidade, por 7 dias. Após moldagem do conduto, foram confeccionados pinos metálicos fundidos e cimentados com fosfato de zinco. Os espécimes permaneceram em câmara úmida por 45 dias antes do teste de tração, realizado em uma máquina universal de ensaios. Os valores foram expressos em Mega pascal (MPa) e submetidos aos testes ANOVA e Tukey (p<0,05). Resultados: O etilcianoacrilato diminuiu a retenção dos pinos metálicos fundidos (p<0,01). Não houve diferença entre os outros grupos (p>0,05), semelhante- mente ao controle. Conclusão: A proteção da obturação com plugs confeccionados com etil-cianoacrilato prejudica a retenção de pinos metálicos fundidos cimentados com fosfato de zinco, enquanto Sealapex® acrescido de óxido de zinco, fosfato de zinco endurecido ou Coltosol® não interferem na adesividade (AU).

Efeito de tratamentos de superfície da resina, cimento resinoso e envelhecimento nas características interfaciais de restaurações semidiretas de resina composta / Effect of resin surface treatments, resin cement and aging on the interfacial characteristics of semi-direct composite resin restorations

A técnica semidireta realizada com resina composta pode ser uma excelente opção de tratamento para restaurações profundas e extensas em dentes posteriores devido às dificuldades técnicas no uso da resina composta pela técnica direta, como também pelos maiores custo e tempo de tratamento das restaurações indiretas com porcelana. O objetivo do estudo foi avaliar o efeito de diferentes tratamentos da superfície da restauração, tipos de cimento resinoso para cimentação e tempos de envelhecimento na durabilidade de união à dentina, padrão de falhas e nanoinfiltração de restaurações semidiretas. Foram utilizados 320 incisivos bovinos (N=320), dos quais foram obtidos discos de 4.0 mm de espessura e, na sua porção mais central, foi confeccionado um preparo cavitário cônico com 4.8 mm de diâmetro superior e 2.8 mm de diâmetro inferior. As amostras foram divididas em 16 grupos de acordo com o cimento resinoso: RelyX Ultimate (ULT) e RelyX U200 (U200); tratamento de superfície da resina: Silano (S), Single Bond Universal (SBU) e S+SBU; e tempo de envelhecimento: 24 horas (24h) e 6 meses (6m). As análises realizadas foram: Resistência de União à extrusão por push out (RU), Padrão de Falha (PF) e Nanoinfiltração (NI). Os dados foram analisados através de estatística descritiva e inferencial utilizando ANOVA Three Way com Post Hoc de Tukey (p<0,005). Para RU, ULT apresentou melhor desempenho em ambos os tempos de envelhecimento. SBU apresentou melhores resultados após 6 m quando associado ao ULT. As médias aumentaram com o tempo para o U200, exceto quando o silano foi utilizado como tratamento de superfície. Na análise do PF, o ULT apresentou o maior percentual de falha mista, quando a fratura ocorreu simultaneamente em dentina ou material restaurador e na interface adesiva, em ambos os tempos de envelhecimento e quando foi utilizado associado ao SBU ou ao S+SBU como tratamento de superfície da resina. Os diferentes tratamentos de superfície e tempos de envelhecimento não influenciaram a nanoinfiltração na interface cimento-resina. De acordo com os resultados encontrados nesse estudo laboratorial, observou-se um melhor desempenho para o ULT e entre os tratamentos de superfície, o uso de SBU possibilitou maior RU após 6 meses quando utilizado com esse cimento, porém não influenciou a nanoinfiltração na interface cimento-resina. Sugere-se que as restaurações semidiretas de resina composta podem ser cimentadas com ULT com SBU como tratamento de superfície da resina, como também com U200, sem a necessidade de nenhum tratamento químico na restauração (AU).

The semi-direct technique performed with composite resin can be an excellent treatment option for deep and extensive restorations on posterior teeth due to technical difficulties in the use of composite resin by the direct technique, as well as the higher cost and time of treatment of indirect restorations with porcelain. The aim of the study was to evaluate the effect of different treatments of the restoration surface, types of resin cement for cementation and aging times on the bond durability to dentin, failure pattern and nanoleakage of semi-direct restorations. 320 bovine incisors were used (N = 320), from which discs of 4.0 mm thickness were obtained and, in its most central portion, a conical cavity preparation with 4.8 mm in diameter and 2.8 mm in diameter was made. The samples were divided into 16 groups according to the resin cement: RelyX Ultimate (ULT) e RelyX U200 (U200); resin surface treatment: Silane (S), Single Bond Universal (SBU) and S+SBU; and aging time: 24 hours (24h) and 6 months (6m). The analyzes performed were: Bond Strength to push-out extrusion (BS), Failure Pattern (FP) and Nanoleakage (NL). The data were analyzed using descriptive and inferential statistics using ANOVA Three Way with Tukey's Post Hoc (p <0.005). For BS, ULT showed better performance in both times of aging. SBU showed better results after 6m when associated with ULT. The averages increased with time for U200, except when silane was used as a surface treatment. In the analysis of the FP, the ULT presented the highest percentage of mixed failure, when the fracture occurred simultaneously in dentin or restored material and at the adhesive interface, at both times of aging and when it was used in association with SBU or S + SBU as treatment resin surface. The different surface treatments and aging times did not influence nanoleakage at the cement-resin interface. According to the results found in this laboratory study, a better performance was observed for the ULT and among the surface treatments, the use of SBU enabled greater BS, however it did not influence the nanoleakage at the cement-resin interface. It is suggested that semi-direct composite resin restorations can be cemented with ULT with SBU as a resin surface treatment, as well as with U200, without the need for any chemical treatment in the restoration (AU).

Solução estética multidisciplinar em dentes anteriores: relato de caso / Multidisciplinary aesthetic solution in previous teeth: case report / Solución estética multidisciplinariaem dientes anteriores: caso clínico

ntrodução:Pacientes com dentes curtos e ameias abertas, relatam muita insatisfação com seusorriso.A gengivoplastia, quando bem indicada, permite oaumento no tamanho da coroa dentária de forma a reduzir a necessidade de aumento incisal com resina composta. A reanatomização com resinas compostas para fechamento de ameias e aumentosincisais representa uma alternativa conservadora, pois trata-se de uma técnicaadesiva diretaque pode ser realizada sem nenhum desgaste dentário. Além disso é uma técnica reversível preferível para pacientes jovens. Objetivo:Apresentar um relato de caso clínico de paciente do sexo masculino, 22 anos, insatisfeito com o tamanho, cor e a forma dos seus dentes anteriores. Descrição do Caso:Ao exame clínico foi observado coroa curta, escurecimento fisiológico, espaços interdentais e desalinhamento das bordas incisais. O plano de tratamento proposto foi encaminhar para a gengivoplastia, clareamento dental pela técnica associada e reanatomização estética dos dentes anteriores com resinacomposta diretaestratificada com diferentescamadas e cores, e posterior texturização superficialdurante as fases de acabamento e polimento finais. Conclusões:Com a gengivoplastiae asrestaurações, obtivemos dentes reanatomizados, reproduzindo naturalidadede forma, textura e cor. Com planejamento e técnica adequada, foi possível restabelecer o sorriso comproporções, forma e naturalidade satisfatórias (AU).

Introduction:Patients with short teeth and open battlements, report a lot of dissatisfaction with their smile. Gingivoplasty, when properly indicated, allows for an increase in the size of the dental crown in order to reduce the need for incisal augmentation with composite resin. Resuscitation with composite resins for the closure of niches and incisal increases represents a conservative alternative, as it is a direct adhesive technique that can be performed without any dental wear. Furthermore, it is a preferable reversible technique for young patients.Objective:To present a case report of a 22-year-old male patient, dissatisfied with the size, color and shape of his anterior teeth.Case Description:The clinical examination showed a short crown, physiological darkening, interdental spaces and misalignment of the incisal edges. The proposed treatment plan was to refer to gingivoplasty, tooth whitening by the associated technique and aesthetic reanatomization of the anterior teeth with stratified direct composite resin with different layers and colors, and later surface texturing during the final polishing and finishing phases. Conclusions:With gingivoplastyand restorations, we obtained reanatomized teeth, reproducing natural form, texture and color. With proper planning and technique, it was possible to restore the smile with satisfactory proportions, shape and naturalness (AU).

Introducción: Los pacientes com dientescortos y almenasabiertas, informanmuchainsatisfaccióncom susonrisa. La gingivoplastia, cuando está indicada adecuadamente, permite un aumento em eltamaño de la corona dental para reducirlanecesidad de aumento incisalcon resina compuesta. La rstauración con resinas compuestas para elcierre de nichos y aumentos incisales representa una alternativa conservadora, ya que es una técnica adesiva directa que se puede realizar sinningún tipo de desgaste dental. Además, es una técnica reversiblepreferible para pacientes jóvenes. Objetivo: Presentar un informe de caso de un paciente masculino de 22 años, insatisfechocom eltamaño, el color y la forma de sus dientes anteriores.Descripcióndel caso:El examen clínico mostró una corona corta, oscurecimiento fisiológico, espaciosinterdentales y desalineación de los bordes incisales. El plan de tratamento propuesto era referirse a lagingivoplastia, elblanqueamiento dental mediante la técnica asociada y lareanatización estética de losdientes anteriores con resina compuestadirecta estratificada con diferentes capas y colores, y luego texturizar lasuperficie durante las fases finales de pulido y acabado. Conclusiones: Com lagingivoplasty yrestauracióndental, obtuvimosdientesreanatomizados, reproduciendo forma, textura y color naturales. Con una planificación y técnica adecuadas, fueposible restaurar lasonrisacon proporciones, forma y naturalidade satisfactorias (AU).

Influence of acidic monomer concentration and application mode on the bond strength of experimental adhesives

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.

In vitro fracture strength and modes of cast post and cores luted with self-adhesive resin-based cement

Aim: Cast post and core (CPC) is the main used post type; however, the biomechanical behavior of CPCs adhesively luted to the dentin is still unclear. Therefore, we aimed to evaluate the fracture resistance (FR) and fracture modes of teeth restored with CPCs luted with zinc-phosphate (ZP) or resin-based self-adhesive (SA) cements, as well as the influence of the coronal remnant. Methods: For that, 24 human premolars were divided into four groups according to the cement (ZP or SA) and coronal remnant (with or without 2mm). FR was tested in a universal machine and data analyzed by two-way ANOVA and Tukey HSD (α=.05). Fracture modes were classified according to the degree of dental destruction. Results: The results showed that there was no difference in FR (p=.352); however, teeth without ferrule presented more irreparable fractures, specially in the ZP group. Conclusion: All in all, self-adhesion of CPCs does not enhance fracture resistance, however it reduces the number of irreparable fractures, compared to ZP cement

Shear bond strength and adhesive remnant index of orthodontic brackets bonded to enamel using adhesive systems mixed with TiO2 nanoparticles

ABSTRACT Introduction: It is recently suggested that titanium dioxide (TiO2) nanoparticles can be added to bracket luting agents in order to reduce bacterial activity and protect the enamel. However, it is not known if this addition can affect the shear bond strength (SBS) below clinically acceptable levels. Therefore, this study examined this matter within a comprehensive setup. Methods: This in vitro experimental study was conducted on 120 extracted human premolars randomly divided into four groups (n=30): in groups 1 and 2, Transbond XT light-cured composite with or without TiO2 was applied on bracket base; in groups 3 and 4, Resilience light-cured composite with or without TiO2 was used. Brackets were bonded to teeth. Specimens in each group (n=30) were divided into three subgroups of 10 each; then incubated at 37°C for one day, one month, or three months. The SBS and adhesive remnant index (ARI) were calculated and compared statistically within groups. Results: The SBS was not significantly different at one day, one month or three months (p>0.05) but composites without TiO2 had a significantly higher mean SBS than composites containing TiO2 (p<0.001). The SBS of Transbond XT was significantly higher than that of Resilience (p<0.001). No significant differences were noted in ARI scores based on the type of composite or addition of TiO2 (p>0.05). Conclusions: Addition of TiO2 nanoparticles to Transbond XT decreased its SBS to the level of SBS of Resilience without TiO2; thus, TiO2 nanoparticles may be added to Transbond XT composite for use in the clinical setting.

RESUMO Introdução: recentemente, sugeriu-se que nanopartículas de dióxido de titânio (TiO2) poderiam ser adicionadas ao cimento adesivo para reduzir a atividade bacteriana e proteger o esmalte. Entretanto, não se sabe se esse acréscimo pode reduzir a resistência adesiva ao cisalhamento (RAC) a níveis inferiores aos clinicamente aceitáveis. Assim, o presente estudo examinou essa questão dentro de um contexto abrangente. Métodos: esse estudo experimental in vitro foi realizado em 120 pré-molares humanos, aleatoriamente divididos em quatro grupos (n=30). Nos grupos 1 e 2, o adesivo fotopolimerizável Transbond XT com e sem TiO2 foi aplicado na base do braquete. Nos grupos 3 e 4, utilizou-se o adesivo fotopolimerizável Resilience com e sem TiO2. Os braquetes foram colados aos dentes e as amostras de cada grupo (n=30) foram divididas em três subgrupos de dez amostras cada, as quais foram incubadas a 37°C por, respectivamente, um dia, um mês e três meses. A RAC e o índice de adesivo remanescente (IAR) foram calculados e estatisticamente comparados entre os grupos. Resultados: a RAC não apresentou diferença significativa após um dia, um mês ou três meses (p > 0,05), mas os adesivos sem TiO2 apresentaram uma RAC média significativamente mais elevada do que os adesivos que continham TiO2 (p< 0,001). A RAC do Transbond XT foi significativamente mais elevada do que a do Resilience (p< 0,001). Não foram observadas diferenças significativas nos IARs, seja para o tipo de adesivo ou para a adição de TiO2 (p> 0,05). Conclusões: a adição de nanopartículas de TiO2 ao Transbond XT reduziu sua RAC a níveis semelhantes aos da RAC do Resilience TiO2. Assim, as nanopartículas de TiO2 podem ser acrescentadas ao adesivo Transbond XT para a aplicação clínica.

Evaluation of shear bond strength and shear stress on zirconia reinforced lithium silicate and high translucency zirconia

This study evaluated the shear stress distribution on the adhesive interface and the bond strength between resin cement and two ceramics. For finite element analysis (FEA), a tridimensional model was made using computer-aided design software. This model consisted of a ceramic slice (10x10x2mm) partially embedded on acrylic resin with a resin cement cylinder (Ø=3.4 mm and h=3mm) cemented on the external surface. Results of maximum principal stress and maximum principal shear were obtained to evaluate the stress generated on the ceramic and the cylinder surfaces. In order to reproduce the in vitro test, similar samples to the computational model were manufactured according to ceramic material (Zirconia reinforced lithium silicate - ZLS and high translucency Zirconia - YZHT), (N=48, n=12). Half of the specimens were submitted to shear bond test after 24h using a universal testing machine (0.5 mm/min, 50kgf) until fracture. The other half was stored (a) (180 days, water, 37ºC) prior to the test. Bond strength was calculated in MPa and submitted to analysis of variance. The results showed that ceramic material influenced bond strength mean values (p=0.002), while aging did not: YZHT (19.80±6.44)a, YZHTa (17.95±7.21)a, ZLS (11.88±5.40)b, ZLSa (11.76±3.32)b. FEA results showed tensile and shear stress on ceramic and cylinder surfaces with more intensity on their periphery. Although the stress distribution was similar for both conditions, YZHT showed higher bond strength values; however, both materials seemed to promote durable bond strength.

Bone Regeneration Using Block-type Deproteinized Porcine Bone Mineral with Collagen Membrane Using 3,4-Dihydroxyphenylalanine as Bone Adhesive

PURPOSE: The purpose of this study was to assess the adhesiveness and cytotoxicity of 3, 4-dihydroxyphenylalanine (DOPA), and to evaluate the role of collagen membrane with DOPA in the guided bone regeneration. MATERIALS AND METHODS: Peel resistance and cell cytotoxicity test were performed. Four defect types in nine rabbit calvaria were randomly allocated: i) control, ii) membrane, iii) deproteinized porcine bone mineral (DPBM) covered by membrane with DOPA, and iv) DPBM covered by membrane with cyanoacrylate. Animals were sacrificed at 2 (n=4) and 8 weeks (n=5) for microcomputed tomography and histomorphometric analysis. DOPA showed low peel resistance but high cell viability. RESULT: Cyanoacrylate and DOPA groups showed significantly higher mineralized tissue volume (MTV) compared to control and membrane groups at 2 weeks (P < 0.05). At 8 weeks, DOPA group showed the highest MTV. Significantly higher new bone area was found in DOPA group at 8 weeks (P < 0.05). Bone formation increased from 2 to 8 weeks in DOPA group (P < 0.05). CONCLUSION: DOPA showed high cell viability and in vivo study revealed predictable performance in bone regeneration.

Minimization of polymerization shrinkage effects on composite resins by the control of irradiance during the photoactivation process

Abstract High levels of shrinkage stress caused by volumetric variations during the activation process are one of the main problems in the practical application of composite resins. Objective The aim of this study is to reduce the shrinkage stress and minimize the effects caused by composite resin volumetric variation due to the photopolymerization. In this way, this work proposes a systematic study to determine the optimal dimming function to be applied to light curing processes. Material and Methods The study was performed by applying mathematical techniques to the optimization of nonlinear objective functions. The effectiveness of the dimming function was evaluated by monitoring the polymerization shrinkage stress during the curing process of five brands/models of composites. This monitoring was performed on a universal testing machine using two steel bases coupled in the arms of the machine where the resin was inserted and polymerized. The quality of the composites cured by the proposed method was analyzed and compared with the conventional photoactivation method by experiments to determine their degree of conversion (DC). Absorbance measurements were performed using Fourier-transform infrared spectroscopy (FT-IR). A T-test was performed on DC results to compare the photoactivation techniques. We also used scanning electron microscopy (SEM) to analyze in-vitro the adhesion interface of the resin in human teeth. Results Our results showed that the use of the optimal dimming function, named as exponential, resulted in the significant reduction of the shrinkage stress (~36.88% ±6.56 when compared with the conventional method) without affecting the DC (t=0.86, p-value=0.44). The SEM analyses show that the proposed process can minimize or even eliminate adhesion failures between the tooth and the resin in dental restorations. Conclusion The results from this study can promote the improvement of the composite resin light curing process by the minimization of polymerization shrinkage effects, given an operational standardization of the photoactivation process.

Study of the chemical interaction between a high-viscosity glass ionomer cement and dentin

Abstract Objective To investigate the chemical interactions between a high-viscosity glass ionomer cement (GIC) (KetacTM Molar Easymix, 3M ESPE, Seefeld, Bavaria, Germany) and human dentin. It was also analyzed the dynamics of GIC setting mechanism based on the time intervals required for the GIC and the GIC mixed with dentin to achieve stability. Material and Methods Each constituent of GIC - powder (P) and liquid (L) - and powdered dentin (D), as well as the associations P+L, D+L, and P+L+D in the concentrations of 29%, 50%, 65%, 78%, 82%, and 92% of GIC were analyzed with Fourier transform infrared (FTIR) and Raman spectroscopy. Results New optical absorption bands and/or Raman bands, which were not present in P, L, or D, were observed in the associations. The concentrations of 29% and 50% of GIC showed higher interaction, revealing that the amount of dentin influences the formation of new optical absorption or scattering bands. FTIR bands showed that the setting time to achieve bond stability was longer for the high-viscosity GIC (38±7 min) than for the sample with 29% of GIC (28±4 min). Conclusions The analysis revealed the formation of new compounds or molecular rearrangements resulting from the chemical interactions between GIC and dentin. Moreover, this study provides an effective method to evaluate the dynamics of the setting mechanism of GICs.

Effect of different bonding protocols on degree of monomer conversion and bond strength between orthodontic brackets and enamel

Abstract The objective of the present study was to evaluate the effect of different surface treatments and polymerization protocols on the bond strength of brackets to enamel, and the degree of conversion of the bonding agents. 120 bovine crowns were embedded in acrylic resin blocks and sanded. Next, the blocks were randomly assigned into 12 groups. Metal brackets were bonded to enamel according to the "surface treatment" factor (A: Phosphoric Acid; ATxt: Phosphoric Acid + Transbond XT Primer®; Tse: Transbond Plus Self Etching Primer®; and SBU: Scotchbond Universal®) and "polymerization" factor (R20: Radii-Cal®/20 seconds; V20: Valo Cordless®/20 seconds; and V3: Valo Cordless®/3 seconds). All samples were stored for 6 months (water, 37ºC) and then subjected to a shear bond strength test (SBS). Bond failures were classified according to the Adhesive Remnant Index (ARI) and analyzed with the Kruskal-Wallis and Mann-Whitney tests (5%). Using the same factors, 120 resin discs were made to assess the degree of conversion (DC) of the monomer. Data from the SBS (MPa) and DC (%) were analyzed by analysis of variance (2 factors) and Tukey's test (5%). For the SBS, the factors "polymerization" (R20 = 8.1B; V20 = 13.2A; V3 = 5.2C, p = 0.0001) and "surface treatment" (A = 3.1C; ATxt = 13.6A; Tse = 12.3A; SBU = 6.3B, p = 0.0001) were statistically significant among groups. The highest adhesion value were found for the ATxt/V20 group (22.2A) and the lowest value for the A/R20 group (1.2E). Regarding ARI, score 2 was the most prevalent in groups A, ATxt, V20 and V3, while score 4 was the most prevalent in the Tse, SBU and R20 groups, with no significant difference between them (p = 1.0). Regarding DC, the factors "polymerization" (R20 = 66.6A; V20 = 58.4B; V3 = 45.1C, p = 0.0001) and "surface treatment" (A = 52B, ATxt = 59.7A, Tse = 51.4B, SBU = 63.8A, p = 0.0001) were statistically significant. Tse was more sensitive to the variations in polymerization protocols than the other surface treatments. Treatment A did not present suitable bond strength or degree of conversion.

Efeito de diferentes estratégias de colagem de bráquetes ortodônticos na resistência de união ao esmalte e no grau de conversão dos monômeros / Effect of different orthodontic bracket bonding strategies on bond strength to enamel and degree of monomer conversion

Objetivo: Avaliar o efeito de diferentes tratamentos de superfície na resistência de união de bráquetes metálicos colados ao esmalte e no grau de conversão dos agentes de colagem, utilizando diferentes protocolos de polimerização. Metodologia: Cento e vinte coroas dentárias de incisivos bovinos foram incluídas em blocos de resina acrílica, lixadas e distribuídas aleatoriamente em 12 grupos. Em seguida, bráquetes metálicos foram colados no esmalte planificado de acordo com os fatores "tratamento de superfície" (A-ácido fosfórico, ATxt-ácido fosfórico+primer Transbond XT®/3M, Tse-Transbond Plus Self Etching Primer®/3M e SBU-Single Bond Universal®/3M) e "polimerização" (R20-Radii-Cal®/20 segundos, V20-Valo Cordless®/20 segundos e V3-Valo Cordless®/3 segundos). As amostras foram armazenadas por 6 meses (água, 370C) e, depois, submetidas ao ensaio de resistência de união cisalhamento (RUC), 300KgF, 1mm/min. Utilizando os mesmos protocolos do ensaio anterior, 120 discos de resina foram confeccionados para análise do grau de conversão (GC). Os dados da RUC (MPa) e do GC (%) foram analisados pelo ANOVA (2 fatores) e Teste de Tukey (5%). As falhas foram classificadas de acordo com o Índice Remanescente Adesivo (IRA) e avaliadas através dos testes Kruskal-Wallis e Mann-Whitney (5%). Resultados: Para a RUC, os fatores "polimerização" (R20=8,146B; V20=13,271A; V3=5, 26C, p=0.0001) e "tratamento de superfície" (A=3,18C ; ATxt=13,63A; Tse=12,38A; SBU=6,37B, p=0.0001) mostraram-se estatisticamente significantes. Os maiores valores de adesão foram encontrados para o grupo ATxtV20 (22,298A) e os menores, para o grupo AR20 (1,27E). Quanto ao IRA, o escore 2 foi o mais prevalente nos grupos A, ATxt, V20 e V3, enquanto que o escore 4 foi o mais prevalente nos grupos Tse, SBU e R20, sem diferença significante entre eles (p=1,0). No que diz respeito ao GC, os fatores "polimerização" (R20=66,67A ; V20=58,48B ; V3=45,12C, p=0.0001) e "tratamento de superfície" (A=52,01B, ATxt=59,71A, Tse=51,47B, SBU=63, 84A, p=0.0001) mostraram-se estatisticamente significantes. Conclusões: O Tse mostrou-se mais sensível às variações nos protocolos de polimerização do que os outros tratamentos de superfície. Já o tratamento A não apresentou valores de RUC e GC adequados para a colagem de bráquetes metálicos ao esmalte (AU)

Objective: To evaluate the effect of different surface treatments and polymerization protocols on the bond strength of brackets to enamel, and the degree of conversion of the bonding agents. Methods: 120 bovine crowns were embedded in acrylic resin blocks and sanded. Next, the blocks were randomly assigned into 12 groups. Metal brackets were bonded to enamel according to the "surface treatment" factor (A: Phosphoric Acid; ATxt: Phosphoric Acid + Transbond XT Primer®; Tse: Transbond Plus Self Etching Primer®; and SBU: Scotchbond Universal®) and "polymerization" factor (R20: Radii-Cal®/20 seconds; V20: Valo Cordless®/20 seconds; and V3: Valo Cordless®/3 seconds). All samples were stored for 6 months (water, 37ºC) and then subjected to a shear bond strength test (SBS). Using the same factors, 120 resin discs were made to assess the degree of conversion (DC) of the monomer. Data from the SBS (MPa) and DC (%) were analyzed by analysis of variance (2 factors) and Tukey's test (5%). Bond failures were classified according to the Adhesive Remnant Index (ARI) and analyzed with the Kruskal-Wallis and Mann-Whitney tests (5%). Results: For the SBS, the factors "polymerization" (R20=8.1B; V20=13.2A; V3=5.2C, p=0.0001) and "surface treatment" (A=3.1C; ATxt=13.6A; Tse=12.3A; SBU=6.3B, p=0.0001) were statistically significant among groups.The highest adhesion value were found for the ATxtV20 group (22.2A) and the lowest value for the A/R20 group (1.2E). Regarding ARI, score 2 was the most prevalent in groups A, ATxt, V20 and V3, while score 4 was the most prevalent in the Tse, SBU and R20 groups, with no significant difference between them (p=1.0). Regarding DC, the factors "polymerization" (R20=66.6A; V20=58.4B; V3=45.1C, p=0.0001) and "surface treatment" (A=52B, ATxt=59.7A, Tse=51.4B, SBU=63.8A, p=0.0001) were statistically significant. Conclusions: Tse was more sensitive to the variations in polymerization protocols than the other surface treatments. Treatment A did not present suitable bond strength or degree of conversion (AU).

Bond strength and adhesive remnant index of experimental brackets bonded with self-adhesive resin cement

ABSTRACT: Aim: To evaluate the shear bond strength (SBS) and adhesive remnant index (ARI) of experimental brackets bonded with self-adhesive resin cement. Ninety bovine teeth were randomly distributed (n = 15) according to the groups: G1 - metal brackets bonded with Transbond™ XT; G2 - APC metal brackets bonded without additional adhesive system; G3 - APC metal brackets bonded with self-etching adhesive system; G4 - metal brackets bonded with RelyXU200; G5 - experimental brackets bonded with Transbond™ XT; G6 - experimental brackets bonded with RelyXU200. Shear bond strength test of the brackets was carried out and after their removal, the ARI was observed. Results: The highest mean value of SBS was found in group 1 (14.33 MPa) and lower mean SBS has been in group 4 (2.36 MPa). The mean values of SBS found in the experimental groups were higher compared to the non-modified brackets. The ARI analysis demonstrated that groups that received the phosphoric acid or selfetching primer (G1,G2,G3andG5) showed adhesive partially and fully adhered to the tooth. Greater amounts of remnants were adhered to the bracket in the experimental brackets, this minimizes the risk of damage to the tooth enamel since it requires minimal finishing. These results suggest that the experimental brackets are interesting options for future use in orthodontics, since it has sufficient adhesive strength to the orthodontic treatment, and less risk of damage to the enamel at the time of removal of the brackets, and is a simple and inexpensive alternative.

Evaluation of bond strength of a conventional adhesive system in irradiated teeth / Avaliação da resistência de união de um sistema adesivo convencional em dentes irradiados

Introduction: One of the most common treatments of head and neck cancer patients is radiotherapy, a treatment method which uses ionizing radiation beam and destroys tumor cells, minimizing damage to neighbor cells. Purpose: To evaluate the bond strength of a conventional adhesive system in irradiated teeth. Method: 24 third human molars, 12 of which were randomly exposed to radiation and prepared from the removal of occlusal enamel, then exposed to a flat dentine surface. The adhesive system Stae was applied according to the manufacturer's instructions. Next, two 2 mm increments of resin were implemented. The samples were hemi sectioned specimens, originating shapped toothpick. To evaluate the bond strength, a micro tensile test was done with 500N load and speed of 0.5 mm/minute. Result: There was no statistically significant difference between the bond strength of teeth which were or were not exposed to radiation and which used a conventional adhesive system. Conclusion: Although the radiation doses applied may cause some alterations in microscopic range in dental tissues, it can be concluded that these alterations do not influence in the bond strength in dentin of irradiated teeth.

Introdução: Um dos tratamentos mais comuns dos pacientes portadores de câncer na região de cabeça e pescoço é a radioterapia, um método de tratamento que utiliza feixe de radiação ionizante e tem por finalidade destruir as células tumorais, minimizando danos às células vizinhas. Objetivo: Avaliar a resistência de união de um sistema adesivo convencional em dentes irradiados. Método: 24 terceiros molares, dos quais 12 foram aleatoriamente expostos à irradiação e preparados a partir da remoção do esmalte oclusal, expondo, dessa forma, uma superfície de dentina. O sistema adesivo Stae foi aplicado de acordo com as instruções do fabricante e em seguida acrescentou-se dois incrementos de resina de 2 mm. Os corpos de prova foram hemi-seccionados originando espécimes em forma de palito. Para avaliação da resistência de união, foi realizado o ensaio de microtração com carga de 500N e velocidade de 0,5mm/min. Resultado: Não houve diferença estatística significante entre a resistência de união de dentes que foram ou não expostos à irradiação e que utilizaram um sistema adesivo convencional. Conclusão: Embora as doses de radiação aplicadas causem algum tipo de alteração em escala microscópica nos tecidos dentários, essas alterações não interferiram na resistência de união.

Influence of Primekote® polymer in orthodontic bonding / Influência do polímero Primekote® na colagem ortodôntica

Objective: The Primekote® (TP) polymer was incorporated to the of Orthodontic Bracket mesh base to improve bond strength and make it more efficient. The purpose of this study was to assess the shear bond strength and adhesive remnant index (ARI) of these brackets. Material and method: The test sample consisted of thirty bovine incisors divided into 2 groups: with a group with TP® brackets (n=15), and a control group with Morelli® brackets (n=15) without Primekote® technology. The TransbondTM XT was used as adhesive system in both groups, following the same protocol and manufacturer’s instructions. Specimens were stored in distilled water for 24 hours and then submitted to shear bond strength test in a universal testing machine (EMIC DL2000). The assessment of ARI was performed under stereomicroscope by two calibrated examiners. Result: No significant differences (p>0.05) in shear bond strength were found between the two groups according to the independent t-test. The Wilcoxon test was used to assess ARI data and statistical difference was found between Morelli® and TP® Nu-Edge brackets; the last one left less remaining adhesive on tooth surface. Conclusion: TP® brackets had higher adherence to the adhesive system as shown by lower ARI scores, but this does not improve its clinical performance.

Objetivo: Avaliar a resistência ao cisalhamento e o índice de remanescente adesivo (IRA) dos bráquetes que tiveram o polímero Primekote® incorporado a suas bases. Material e método: Foram confeccionados trinta corpos de prova com incisivos bovinos, divididos em dois grupos: o colado com bráquete TP® Nu-Edge(n=15) e grupo controle com bráquetes Morelli® (n=15) sem tratamento na base. O sistema adesivo TransbondTM XT foi utilizado nos dois grupos seguindo o mesmo protocolo de colagem e respeitando as instruções do fabricante. Os corpos de prova foram armazenados em água destilada por 24 horas, e posteriormente submetidos ao teste de cisalhamento na máquina de ensaios universais (EMIC-DL2000). O IRA foi avaliado por dois examinadores calibrados utilizando lupa estereoscópica com aumento de 20 vezes. Resultado: Na resistência ao cisalhamento o teste T-independente mostrou não haver diferença estatisticamente significante entre os grupos (p>0,05), ambos tiveram desempenho semelhante. O teste Wilcoxon foi utilizado nos valores obtidos no IRA revelando diferença estatística, sendo que os bráquetes TP® deixaram menos remanescente adesivo na superfície dental que os bráquetes Morelli®. Conclusão: Bráquetes TP® apresentaram maior adesão ao sistema adesivo pois foi encontrado menor IRA nos mesmos, porém esta característica não reflete em melhora no desempenho clínico.