Efeito de diferentes tratamentos de superfície na resistência ao cisalhamento entre uma resina nanohíbrida para impressão 3D e cimento resinoso / Effect of different surface treatments on the shear strength between a nanohybrid resin for 3D printing and resin cement

O objetivo deste trabalho foi avaliar a resistência de união entre uma resina nanohíbrida para impressão 3D com cimento resinoso após diferentes tratamentos de superfície e envelhecimento. Foram fabricados 120 blocos da resina nanohíbrida (Nanolab 3D, Wilcos do Brasil) em tamanhos de 10 x 8 x 2 mm, desenhados no software Rhinoceros 7 e depois impressos (W3D PRINT, Wilcos do Brasil) por método digital de processamento de luz (LCD). Foram produzidos também blocos de mesmo tamanho obtidos a partir de blocos de CAD/CAM de uma resina híbrida (Hybrid, Blue Dent), como grupo controle. Cinco tratamentos de superfície foram realizados nos blocos de resina: nenhum tratamento, condicionamento ácido com ácido fluorídrico, jateamento com Al3O2, imersão em monômero de metilmetacrilato (primer) e um grupo somando o jateamento com imersão em primer. Foram construídos cilindros (< 1 mm2) de cimento resinoso convencional dual sobre as superfícies tratadas com auxílio de matriz de silicone. A resistência de união foi medida usando uma máquina de ensaio universal e um teste de microcisalhamento com fio. Metade das amostras de cada grupo foram testadas sete dias após a cimentação, já a outra metade foi termociclada por 12.000 ciclos térmicos (5-55 ºC, 30 segundos cada) e ensaiadas a seguir. Os modos de falha foram analisados por um estereomicroscópio e imagens representativas foram realizadas com o auxílio do microscópio eletrônico de varredura. Após a análise inferencial com ANOVA 3-fatores foi possível observar que houve diferença estatisticamente significante tanto para os fatores material, tratamento de superfície e envelhecimento isoladamente, como para as interações entre eles. A resina híbrida de impressão mostrou maior resistência de união quando comparada com os blocos CAD/CAM. A ciclagem térmica aumentou a resistência de união das resinas impressas e diminuiu a mesma nos blocos de CAD/CAM. É possível concluir que a aplicação de silano é o melhor tratamento de superfície para as resinas de impressão 3D já que proporcionou bons valores de resistência de união e confiabilidade da interface adesiva. A resistência adesiva a longo prazo da resina híbrida de impressão 3D (Nanolab) é influenciada positivamente pelo envelhecimento (AU)

The objective of this work was to evaluate the bond strength between a nanohybrid resin for 3D printing with resin cement after different surface treatments and aging. 120 blocks of nanohybrid resin (Nanolab 3D, Wilcos do Brasil) were manufactured in sizes of 10 x 8 x 2 mm, designed in the Rhinoceros 7 software and then printed (W3D PRINT, Wilcos do Brasil) by digital light processing method (LCD ). Blocks of the same size obtained from CAD/CAM blocks of a hybrid resin (Hybrid, Blue Dent) were also produced as a control group. Five surface treatments were performed on the resin blocks: no treatment, acid etching with hydrofluoric acid, sandblasting with Al3O2, immersion in methylmethacrylate monomer (primer) and one group adding the sandblasting with immersion in primer. Cylinders (< 1 mm2) of conventional dual resin cement were built on the surfaces treated with the aid of a silicone matrix. Bond strength was measured using a universal testing machine and a wire microshear test. Half of the samples from each group were tested seven days after cementation, while the other half was thermocycled through 12,000 thermal cycles (5-55 ºC, 30 seconds each) and then tested. Failure modes were analyzed using a stereomicroscope and representative images were taken using a scanning electron microscope. After the inferential analysis with 3-way ANOVA, it was possible to observe that there was a statistically significant difference both for the material, surface treatment and aging factors alone, as well as for the interactions between them. The hybrid impression resin showed higher bond strength when compared to the CAD/CAM blocks. Thermal cycling increased the bond strength of printed resins and decreased it in CAD/CAM blocks. It is possible to conclude that silane application is the best surface treatment for 3D printing resins as it provided good bond strength values and reliability of the adhesive interface. The long-term adhesive strength of the 3D printing hybrid resin (Nanolab) is positively influenced by aging. (AU)

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

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).

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.

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).

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).

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

Efeito da radioterapia na resistência de união entre dentina humana e resina composta / Effect of radiotherapy on the bond strength between human dentin and composite resin

Objetivo: O objetivo deste estudo experimental é avaliar o efeito da radiação com raios X de alta energia na resistência de união entre dentina humana e resina composta. Métodos: Trinta terceiros molares humanos hígidos foram seccionados, produzindo superfícies oclusais planas de dentina, e distribuídos aleatoriamente em dois grupos (n=15): um não irradiado e restaurado com Resina Composta Filtek Z-250, 3M-ESPE® (G1, n=15 ­ grupo controle), outro irradiado e restaurado com Resina Composta Filtek Z-250, 3M-ESPE® (G2, n=15). O protocolo de radiação utilizado foi de 70 Gy no total. As amostras foram cortadas em palitos (área média de 1 mm2) e submetidas ao teste de microtração. Os dados foram comparados por meio do teste t-student (p <0,05). O padrão de fratura foi examinado em microscopia óptica e submetido ao teste exato de Fischer (p <0,05). Resultados: não houve diferença significativa entre o grupo de dentes não irradiados e irradiados (p=0,738). O grupo controle e o grupo irradiado apresentaram predominância no padrão de fratura de falhas coesivas em resina e/ou mistas e falhas adesivas foram verificadas somente no grupo dos dentes irradiados. Conclusões: A radiação não interfere significativamente na resistência de união da dentina humana restaurada com resina composta e que não houve influência significativa entre os grupos estudados em relação ao padrão de fratura(AU)

Objective: The aim of this experimental study is to evaluate the effect of high-energy x-rays radiation on the bond strength between human dentin and composite resin. Methods: Thirty healthy human third molars were sectioned, producing plane occlusal surface of dentine, and they were randomly distributed in two groups (n=15): one non-irradiated and restored with Composite Resin Filtek Z-250, 3M-ESPE® (G1, n=15 ­ control group), another was irradiated and was restored with Filtek Z-250, 3M-ESPE® (G1, n=15). The radiation protocol used was 70 Gy in total. The samples were cut in sticks (average area of 1 mm2) and were submitted to microtensile test. Data were compared using the t-student (p<0.05) test. The fracture pattern was examined in optical microscopy and was submitted to Fisher's exact test (p<0.05). Results: there was no significant difference between the group of non-irradiated and irradiated teeth (p=0.738). The control group and the irradiated group showed predominance in the fracture pattern of cohesive resin faults and/or mixed and adhesive failures were verified only in the group of irradiated teeth. Conclusions: The radiation does not significantly interfere in bond strength of human dentin restored with composite resin and there was no significant influence between the studied groups in relation of the fracture pattern(AU)

Resistência à compressão, flexão e tração diametral de cimentos resinosos em tempos diferentes de armazenamento / Compressive, flexural and diametral tensile strength of resin cements in different storage times

Objetivos: O objetivo desse estudo foi avaliar a resistência à compressão, tração diametral e flexão de dois cimentos resinosos de presa dual. Métodos: foi utilizado o cimento autoadesivo RelyX U200 (3M ESPE) e o cimento convencional Variolink II (Ivoclar Vivadent). Foram confeccionados corpos de prova cilíndricos com 4mm de diâmetro x 6mm de altura para o teste de compressão, 6mm de diâmetro x 2mm de altura para o teste de tração diametral (ISO 9917-1:2007) e em forma de barra com 25mm de comprimento x 2mm de altura e largura para o teste de flexão três pontos (ISO 4049:2009). As amostras foram armazenadas por 24h (n = 10) e 45 dias (n = 10) em água destilada a 37ºC. Os testes foram realizados em uma máquina universal de ensaios EMIC (DL 2000) com uma célula de carga de 2000 Kgf para o teste de compressão e 200 Kgf para os testes de tração diametral e flexão, à uma velocidade de 0,5 mm/min. Os dados foram submetidos à análise de variância dois critérios (ANOVA) e as médias comparadas pelo teste de Tukey (5%). Resultados: os resultados mostraram valores estatisticamente similares para todas as propriedades mecânicas avaliadas entre todos os cimentos e tempos de armazenamento estudados. Conclusões: A composição química dos cimentos resinosos e o armazenamento em água por 45 dias não foram suficientes para ocasionar alterações nas propriedades mecânicas avaliadas nesse estudo(AU)

Objectives: the aim of this study was to evaluate the compressive, diametral tensile and flexural strength of two dual resin cements. Materials and methods: RelyX U200 self-adhesive cement (3M ESPE) and the conventional Variolink II cement (Ivoclar Vivadent) were used. The test consisted in the preparation of cylindrical specimens measuring 4mm diameter x 6mm height for compression test, 6mm diameter x 2mm height for diametral tensile test (ISO 9917-1: 2007) and in shape of bar with 25mm length x 2mm height and width for three-point bending test (ISO 4049: 2009). The samples were stored for 24 h (n = 10) and 45 days (n = 10) in distilled water at 37°C. The tests were performed in a universal EMIC testing machine (DL 2000) with a load of 2000 Kgf for compressive test and 200 Kgf for diametral tensile and flexural strength tests at a crosshead speed of 0.5 mm/min. The data were submitted to analysis of variance (two-way ANOVA), and the means were compared by the Tukey test (5%). Results: the results showed statistically similar values of all the mechanical properties evaluated between all the resin cements and storage times. Conclusions: The chemical composition of the resin cements and storage in water for 45 days were not enough to cause changes in the mechanical properties evaluated in this study(AU)

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).

Avaliação da resistência de união de reparos em resinas bulk fill após diferentes protocolos de adesão / Evaluation of the bond strength of repairs in bulk fill resins after different adhesion protocols

Objetivo: Avaliar a resistência de união à microtração de reparos realizados em resinas compostas bulk fill e convencional submetidas a envelhecimento, após diferentes protocolos de adesão. Materiais e métodos: Foram confeccionados 42 corpos de prova (8x8x4 mm3 ) de cada um dos seguintes materiais, na cor A1: uma resina composta micro-híbrida (Filtek Z250 XT ­ 3M ESPE, St. Paul, MN, EUA) e uma do tipo bulk fill de consistência regular (Filtek Bulk Fill ­ 3M ESPE, St. Paul, MN, EUA). Estes corpos de prova foram envelhecidos por armazenamento em saliva artificial a 37°C por 30 dias, após os quais receberam um tratamento mecânico de superfície por meio da abrasão com ponta diamantada tronco-cônica de granulação fina 4138F e, então, foram divididos em seis grupos, de acordo com o protocolo de adesão empregado: FSA ­ condicionamento com ácido fosfórico a 35% + silano + adesivo convencional de dois passos (Adper Single Bond 2 - 3M ESPE, St. Paul, MN, EUA); SA ­ silano + adesivo convencional; FA ­ condicionamento com ácido fosfórico a 35% + adesivo convencional; A ­ adesivo convencional; FU ­ ácido fosfórico a 35% + adesivo universal (Single Bond Universal - 3M ESPE, St. Paul, MN, EUA); U ­ adesivo universal. Todos os corpos de prova foram reparados com a resina Z250 XT, na cor B3, para diferenciar dos materiais de base. Os blocos de resinas reparadas foram cortados em palitos (8x1x1 mm3 ) e submetidos ao teste de microtração. Os espécimes fraturados foram avaliados por macrofotografia para determinação do tipo de fratura (adesiva ou coesiva). Para analisar as diferenças entre os protocolos de adesão e entre os tipos de resina composta foi utilizado o teste estatístico ANOVA dois fatores, com nível de significância de 5%. Resultados: Não foram encontradas diferenças estatisticamente significantes nos valores de resistência de união entre os protocolos de adesão e entre as resinas compostas reparadas, assim como não se verificou interação entre estas variáveis. Conclusão: Para o padrão de envelhecimento adotado neste estudo, a resistência de união de reparos em uma resina do tipo bulk fill foi similar à encontrada em uma resina micro-híbrida convencional, não havendo distinção entre diversos protocolos de adesão (AU).

Objective: To evaluate the microtensile bond strength of repairs performed on bulk fill and conventional composite resins subjected to aging, after different adhesion protocols. Materials and methods: 42 specimens (8x8x4 mm3 ) of each of the following materials were prepared in shade A1: a microhybrid composite (Filtek Z250 XT-3M ESPE, St. Paul, MN, USA) and a high-viscosity bulk fill composite (Filtek Bulk Fill - 3M ESPE, St. Paul, MN, USA). These specimens were aged by storage in artificial saliva at 37 ° C for 30 days. After, they received a mechanical surface treatment by means of abrasion with a diamond bur 4138F, followed by the division in six groups, according to the adhesion protocol employed: FSA - etching with 35% phosphoric acid + silane + etch-and-rinse adhesive (Adper Single Bond 2 - 3M ESPE, St. Paul, MN, USA); SA - silane + etch-and-rinse adhesive; FA - etching with 35% phosphoric acid + etch-and-rinse adhesive; A - etch-and-rinse adhesive; FU - 35% phosphoric acid + universal adhesive (Universal Bond Single - 3M ESPE, St. Paul, MN, USA); U - universal adhesive. The repairs were performed with Z250 XT composite, in shade B3, to differentiate them from the base materials. The repaired resin blocks were cut into sticks (8x1x1 mm3 ) and submitted to microtensile test. Fractured specimens were evaluated by macrophotography to determine the type of fracture (adhesive or cohesive). In order to analyze the differences among the adhesion protocols and composite types, two-way ANOVA statistical test was used, with a significance level of 5%. Results: No statistically significant differences were found in bond strength values among the adhesion protocols and among the composite resins repaired, as well as no interaction between these variables. Conclusion: For the aging pattern adopted in this study, repair bond strength of a bulk fill composite was similar to that found in a conventional microhybrid composite, with no distinction among several adhesion protocols (AU).

Influência da oleosidade resultante da lubrificação da caneta de alta rotação na adesão da resina composta ao esmalte / Influence of oil contamination resulting from lubrication of high-speed handpieces in the bonding of composite resin to enamel

A restauração de dentes por sistemas adesivos é rotina em odontologia. O tratamento do esmalte inicia-se pela profilaxia e asperização dos prismas. A manobra é feita com brocas adaptadas à canetas de alta ou baixa rotação as quais devem ser lubrificadas frequentemente. Diversos fatores podem provocar falhas nas restaurações, entre eles a contaminação por oleosidade. A proposta do trabalho foi verificar a influência da lubrificação das pontas de alta rotação na adesão de resinas compostas ao esmalte. Foram confeccionados 30 corpos de provas, constituídos de cilindros de PVC, nos quais se incluiu fragmento da superfície vestibular de dente bovino em resina acrílica autopolimerizável, de maneira paralela ao solo, com área suficiente para a colagem de braquete de 9 mm2. A amostra foi dividida em três grupos de 10. No primeiro (A), cada braquete foi colado de maneira convencional com uma asperização prévia do esmalte realizada com caneta sem lubrificação. No segundo (B), foi realizada asperização com caneta lubrificada e pré-acionada por 30 segundos. E no terceiro (C), a asperização foi feita imediatamente após a lubrificação. Cada braquete foi submetido ao teste de tração. Todas as falhas foram coesivas, apresentando valores médios de 73,18N para o grupo A, 75,90N para o B e 91,45N para o C. O tratamento estatístico não mostrou diferença significativa entre os grupos. De acordo com o método instituído não houve influência da lubrificação das pontas de alta rotação na adesão de resinas compostas ao esmalte (AU).

The use of adhesive systems is a routine procedure in restorative dentistry. Enamel treatment starts with prophylaxis and abrasion of enamel prisms. This is performed using drills adapted to high or slow speed handpieces which must be frequently lubricated. Many factors may produce failure in tooth restoration, among them is the contamination by oil. The purpose of this study was to assess the influence of high speed handpiece lubrication in bond strength of composite resin to enamel. Thirty specimen were made constituted of PVC cylinders, in which were included fragments of the vestibular surface of the bovine tooth in self-polymerized acrylic resin parallel to the floor with sufficient area for bonding the 9 mm2 bracket. The samples were divided randomly into three groups of 10. In the first group (A), the bracket was bonded using the conventional way and enamel abrasion was previously performed with an unlubricated handpiece. In the second one (B), abrasion was performed with a lubricated handpiece which was run on air for 30 seconds and in the third group (C), abrasion was made immediately after lubrication. A tensile test was carried out for each bracket. All failures were cohesive with mean values of 73,18N (group A), 75,90N (group B) and 91,45N (group C). Statistical tests detected no significant differences between the groups. According to the established method, there was no influence of high speed handpiece lubrication on bond strength of composite resin to enamel (AU).

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.

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.

Avaliação da resistência adesiva e características da zircônia após diferentes tratamentos de superfície / Bond strength and surface characteristics evaluation of zirconia after different treatments

O objetivo desse estudo in vitro foi avaliar a resistência adesiva, rugosidade superficial, ângulo de contato e o espectro infravermelho da zircônia, após diferentes tratamentos de superfície. Para isso, blocos (n=9) de zircônia Y-TZP (e.max ZirCad - Ivoclar, Schann, Liechtenstein) foram seccionados em 39 fatias (12 x 11x 3 mm) divididas em grupos de acordo com cada teste. Para resistência adesiva, 20 fatias foram divididos em: 2 grupos controle; JAT, jateamento com óxido de alumínio e sílica + primer (Monobond Plus - Ivoclar, Schann, Liechtenstein); HFP, condicionamento com ácido fluorídrico 10% + primer, e 3 experimentais: PL, plasma (Plasma Não Térmico de Superfície - modelo SAP); PLP, plasma + primer; HFPLP, ácido fluorídrico + plasma + primer. Cada fatia de zircônia foi cimentada (Multilink N - Ivoclair, Schann, Liechtenstein) a um bloco pré-polimerizado de resina composta. Após a cimentação os espécimes foram seccionados, e 48 palitos com área adesiva de 1 mm2 foram obtidos em cada grupo para o ensaio de microtração (µTBS). Quatro outras fatias foram submetidas à análise de rugosidade superficial e 12 fatias submetidas à análise do ângulo de contato, após os seguintes tratamentos de superfície: sem tratamento (AV), aplicação de ácido fluorídrico a 10% (AHF), aplicação de plasma (AP) e jateamento (AJ), sendo que para o ângulo de contato foram feitas medições imediatamente após o tratamento, após 12 e 24 horas. Os resultados foram submetidos à análise estatística Anova e teste de Tukey a 5% (p< 0,05). Os espectros das ligações químicas da superfície da zircônia foram determinados em 3 outras amostras após as seguintes condições: sem tratamento (AV), jateamento (JAT) e aplicação de ácido fluorídrico 10% seguido da aplicação do plasma (AHFP). Em termos de adesão, não houve diferença estatística significante entre os grupos JAT e HFPLP, porém esses 2 foram estatisticamente superiores ao grupos HFP, PL e PLP. O jateamento demonstrou aumentar significantemente a rugosidade superficial em relação aos demais grupos. O plasma demonstrou diminuir o ângulo de contato da superfície da zircônia imediatamente e ao longo de 48 horas(AU)

The purpose of this in vito study was to evaluate zirconia bond strength, surface roughness, contact angle and to mesure infrared spectrum after different surface treatments. Y-TZP zirconium (e.max ZirCAD - Ivoclair, Schann, Liechtenstein) blocks (n=9) were sliced into 36 discs (12 x 11 x 3 mm) and divided (n=4) into surface treatment groups as following: two control groups: JAT, airborneparticle abrasion and HFP, 10% hydrofluoric acid etching + primer (Monobond Plus - Ivoclair, Schann, Liechtenstein)application ,and three experimental groups: PL, non-thermal plasma (Surface Non-Thermal Plasma SAP model) application; PLP non-thermal plasma + primer application, and HFPLP, 10% hydrofluoric acid etching + non-thermal plasma + primer application. Each zirconia disk was cemented (Multilink N - Ivoclair, Schann, Liechtenstein) to a pre-polymerized resin block (Filtek Z350 - 3M, St Paul, MN, USA). After cementation the specimens were sectioned and 48 sticks with adhesive area of 1 mm2 obtained from each group for micro-tensile testing (µTBS). Four discs were submitted to surface roughness analysis and 12 discs to contact angle analysis, after the following surface treatments: no treatment (AV), 10% hydrofluoric acid etching (AHF), non-thermal plasma application (AP); and airborne- particle abrasion (AJ). The results were submitted to ANOVA and Tukey's test (p < 0.05). Zirconia surface chemical bonds spectrum was determined in infrared spectroscopy for three specimens after the conditions: no treatment; airborne- particle abrasion and hydrofluoric acid etching + non-thermal plasma application. The results showed no statistically significant differences between the groups JAT and HFPLP, but these two groups were statistically superior to HFP, PL and PLP. Airborne- particle abrasion resulted in a significant increase of surface roughness compared to the other groups. Non-thermal plasma was shown to decrease the contact angle of the surface, within 48 hours(AU)

Influence of antimicrobial solutions in the decontamination and adhesion of glass-fiber posts to root canals

AbstractObjective This study evaluated the effect of root canal disinfectants on the elimination of bacteria from the root canals, as well as their effect on glass-fiber posts bond strength.Material and Methods Fifty-three endodontically treated root canals had post spaces of 11 mm in length prepared and contaminated with E. faecalis. For CFU/ml analysis, eight teeth were contaminated for 1 h or 30 days (n=4). Teeth were decontaminated with 5% NaOCl, 2% CHX, or distilled water. As control, no decontamination was conducted. After decontamination, sterile paper points were used to collect samples, and CFU/ml were counted. For push-out, three groups were evaluated (n=15): irrigation with 2.5% NaOCl, 2% CHX, or sterile distilled water. A bonding agent was applied to root canal dentin, and a glass-fiber post was cemented with a dual-cured cement. After 24 h, 1-mm-thick slices of the middle portion of root canals were obtained and submitted to the push-out evaluation. Three specimens of each group were evaluated in scanning electron microscopy (SEM). Data were analyzed with one-way ANOVA and Dunnett’s T3 test (α=0.05).Results The number of CFU/ml increased from 1 h to 30 days of contamination in control and sterile distilled water groups. Decontamination with NaOCl was effective only when teeth were contaminated for 1 h. CHX was effective at both contamination times. NaOCl did not influence the bond strength (p>0.05). Higher values were observed with CHX (p<0.05). SEM showed formation of resin tags in all groups.Conclusion CHX showed better results for the irrigation of contaminated root canals both in reducing the bacterial contamination and in improving the glass-fiber post bonding.

A microleakage study of gutta-percha/AH Plus and Resilon/Real self-etch systems after different irrigation protocols

The development and maintenance of the sealing of the root canal system is the key to the success of root canal treatment. The resin-based adhesive material has the potential to reduce the microleakage of the root canal because of its adhesive properties and penetration into dentinal walls. Moreover, the irrigation protocols may have an influence on the adhesiveness of resin-based sealers to root dentin. Objective: The objective of the present study was to evaluate the effect of different irrigant protocols on coronal bacterial microleakage of gutta-percha/AH Plus and Resilon/Real Seal Self-etch systems. Material and Methods: One hundred ninety pre-molars were used. The teeth were divided into 18 experimental groups according to the irrigation protocols and filling materials used. The protocols used were: distilled water; sodium hypochlorite (NaOCl)+eDTA; NaOCl+H3PO4; NaOCl+eDTA+chlorhexidine (CHX); NaOCl+H3PO4+CHX; CHX+eDTA; CHX+ H3PO4; CHX+eDTA+CHX and CHX+H3PO4+CHX. Gutta-percha/AH Plus or Resilon/Real Seal Se were used as root-filling materials. The coronal microleakage was evaluated for 90 days against Enterococcus faecalis. Data were statistically analyzed using Kaplan-Meier survival test, Kruskal-Wallis and Mann-Whitney tests. Results: No significant difference was verified in the groups using chlorhexidine or sodium hypochlorite during the chemo-mechanical preparation followed by eDTA or phosphoric acid for smear layer removal. The same results were found for filling materials. However, the statistical analyses revealed that a final flush with 2% chlorhexidine reduced significantly the coronal microleakage. Conclusion: A final flush with 2% chlorhexidine after smear layer removal reduces coronal microleakage of teeth filled with gutta-percha/AH Plus or Resilon/Real Seal SE. .

Lack of correlation between tubular dentine cement penetration, adhesiveness and leakage in roots filled with gutta percha and an endodontic cement based on epoxy amine resin

Objective: To analyze possible correlations among tubular dentine cement penetration, adhesiveness and apical leakage in fillings performed with gutta percha and an endodontic cement based on epoxy amine resin. Material and Methods: Sixty similar, extracted human mandibular central incisors were irrigated, instrumented and filled following the same protocol. First, apical leakage was quantified by fluid filtration tests. Then, these same specimens were sectioned for analysis of tubular dentine cement penetration and the middle thirds were submitted to push-out tests to analyze the adhesiveness of the fillings. Results: In brief, the means and standard deviations with a confidence interval of 95% were as follows: tubular dentine cement penetration (8.875±4.540), adhesiveness (4.441±2.683) and apical leakage (0.318±0.215). The data were confronted using the Pearson's test (P>0.05), and it was possible to prove that there was no correlation between (1) tubular dentine cement penetration and apical leakage (r2: 0.08276), (2) tubular dentine cement penetration and adhesiveness (r2: -0.2412) and (3) adhesiveness and apical leakage (r2: 0.1340). Conclusion: After analysis of these data, it could be observed that there exists no correlation among the variables analyzed in this study. .