Effect of Ceramic Thickness on the Bond Strength to Resin-Luting Agents before and after Thermal Cycling

Abstract This study investigated microshear bond strength (µSBS) of two (2) dual-cured resin-luting agents (RelyX™ Ultimate and RelyX™ U200) when photoactivated through varying thicknesses of lithium disilicate, with or without thermal cycling. Discs of IPS e.max Press of 0.5, 1.5, and 2 mm in thickness were obtained. Elastomer molds (3.0 mm in thickness) with four cylinder-shaped orifices 1.0 mm in diameter, were placed onto the ceramic surfaces and filled with resin-luting agents. A Mylar strip, glass plate, and load of 250 grams were placed over the filled mold. The load was removed and the resin-luting agents were photoactivated through the ceramics using a single-peak LED (Radii Plus.) All samples were stored in distilled water at 37oC for 24 h. Half of the samples were subjected to thermal cycling (3,000 cycles; 5ºC and 55ºC). All samples were then submitted to µSBS test using a universal testing machine (Instron 4411) at a crosshead speed of 0.5 mm/min. Data were submitted to three-way ANOVA and Tukey post-hoc test (α=0.05). The mean µSBS at 24 h was significantly higher than after thermal cycling (p<0.05). No statistical difference was found between resin-luting agents (p > 0.05). The mean µSBS for groups photoactivated through 0.5 mm ceramic were significantly higher than 1.5 mm and 2.0 mm (p < 0.05). In conclusion, increased ceramic thicknesses reduced the bond strength of tested resin-luting agents to lithium disilicate. No differences were found between resin-luting agents. Thermal cycling reduced the bond strength of both resin-luting agents.

Resumo: Este estudo investigou a resistência de união ao microcisalhamento (RUµC) de dois (2) agentes de cimentação de resina dual (RelyX™ Ultimate e RelyX™ U200) quando fotoativados através de diferentes espessuras de dissilicato de lítio, com ou sem ciclagem térmica. Discos do IPS e.max Press de 0,5, 1,5 e 2 mm de espessura foram obtidos. Moldes de elastômero (3,0 mm de espessura) com quatro orifícios cilíndricos de 1,0 mm de diâmetro foram colocados sobre as superfícies cerâmicas e preenchidos com agentes de cimentação de resina. Uma tira Mylar, placa de vidro e carga de 250 gramas foram colocadas sobre o molde preenchido. A carga foi removida e os agentes de cimentação resinosos foram fotoativados através da cerâmica usando um LED de pico-único (Radii Plus). Todas as amostras foram armazenadas em água deionizada a 37oC por 24 h. Metade das amostras foi submetida a ciclagem térmica (3.000 ciclos; 5ºC e 55ºC). Todas as amostras foram então submetidas ao teste de RUµC usando uma máquina de teste universal (Instron 4411) com velocidade de 0,5 mm/min. Os dados foram submetidos à Análise de Variância três fatores e ao teste post-hoc de Tukey (α = 0,05). A média de RUµC em 24 h foi significativamente maior do que após a ciclagem térmica (p < 0,05). Não houve diferença estatística entre os cimentos resinosos (p > 0,05). As médias de RUµC para grupos fotoativados através de cerâmica de 0,5 mm foram significativamente maiores do que 1,5 mm e 2,0 mm (p < 0,05). Em conclusão, o aumento da espessura da cerâmica reduziu a resistência de união dos agentes de cimentação resinosos ao dissilicato de lítio. Não foram encontradas diferenças entre os agentes de cimentação resinosos. A ciclagem térmica reduziu a resistência de união de ambos os agentes de cimentação resinosos.

Evaluación in vitro de la fuerza de desprendimiento y de la filtración marginal de coronas provisorias fijadas con diferentes agentes cementantes / In vitro evaluation of retention force and marginal leakage of temporary crowns using different luting agents

Objetivo: Analizar mediante pruebas in vitro la fuerza de desprendimiento y la microfiltración marginal de restauraciones coronarias temporales, realizadas sobre premolares, confeccionadas con tres tipos de resinas acrílicas y cementadas con tres materiales de fijación. Materiales y métodos: Se utilizaron 108 premolares a los que se les tallaron pilares con paredes convergentes hacia oclusal (8°), desgaste de 0,8 mm y chánfer a nivel adamantino. Las muestras fueron distribuidas en dos grupos: 54 muestras, para pruebas de desprendimiento; y 54, para pruebas de filtración. Los materiales utilizados en la confección de las coronas fueron: grupo A, resina de acrílico reticulado con relleno de micropartículas (Sistema Cerec, Sirona), grupo B, resina Duralay (Reliance Dental) y grupo C, resina Luxatemp (DMG). Para el cementado se emplearon: subgrupo I, cemento de hidróxido de calcio (Dycal; Dentsply); subgrupo II, cemento de óxido de zinc con el agregado de fluoruros, clorhexidina y nitrato de potasio (GC Temp Advantage; American In); subgrupo III, cemento de ZnO con el agregado de silicona y silano (Temposil; Coltène). Se desarrolló el estudio in vitro de la fuerza de desprendimiento y se realizó un análisis de correlación entre la fuerza (N) requerida para el desalojo de las coronas y la superficie de unión corona-diente (mm2). El análisis de filtración fue efectuado con lupa estereoscópica Olympus (20X y 32X), posicionando las muestras sobre portaobjeto y accionando luz incidente blanca. Por contraste colorimétrico, se determinó el grado de filtración por la penetración longitudinal del colorante en la interfaz diente-restauración. Resultados: Se encontró correlación significativa entre la fuerza requerida para el desalojo de las coronas y la superficie de unión corona diente (correlación de Pearson: 0,423, P=0,0001). Los valores medios obtenidos de la fuerza de desprendimiento fueron: grupo A, 41,09 N; grupo B, 43,52 N; grupo C, 41,26 N, sin diferencias significativas (P=0,484). Con respecto al factor cemento, subgrupo I, 56,87 N; subgrupo II, 40,75 N; y subgrupo III, 28,25 N, y la diferencia fue estadísticamente significativa (P=0,0001). En relación con las pruebas de filtración marginal in vitro considerando solo el factor categoría corona, se observó que los valores de longitud de filtración estuvieron dentro de rangos similares en los tres grupos, aunque el grupo B registró los valores más altos. Teniendo en cuenta solo el factor cemento, el subgrupo II arrojó los valores más bajos, en tanto que los subgrupos I y III registraron valores semejantes y algo mayores, con una media de 0,94 mm y 1,00 mm, respectivamente. La combinación que arrojó menor penetración fue la del grupo A con el subgrupo II (media de 0,62 mm), en tanto que la combinación con valores de longitud o profundidad de filtración más elevados fue la del grupo B con el subgrupo III (media de 1,25 mm), aunque no se alcanzaron diferencias estadísticamente significativas. Conclusión: Se pudo observar que las coronas cementadas con hidróxido de calcio generan las mejores condiciones referidas a la fuerza de desprendimiento, y que las confeccionadas por el sistema Cerec Sirona, mediante tecnología CAD-CAM y cementadas con cemento de óxido de zinc con el agregado de fluoruros, clorhexidina y nitrato de potasio, podrían ofrecen mejores propiedades en cuanto a la filtración marginal (AU)

Aim: To in-vitro analyze the detachment force and the marginal leakage of bicuspid temporary crowns made with three types of acrylic resins and cemented with three luting agents, Materials and methods: 108 premolars were used to drill 0.8 mm depth preparations with 8° taper and chamfer at adamantine level. Half of the specimens were used for detachment tests and the other for leakage. Temporary crowns were fabricated using: group A, acrylic resin with microparticle fillers (Cerec System, Sirona); group B, Duralay resin (Reliance Dental); and group C, Luxatemp resin (DMG). Dycal calcium hydroxide cement (Dentsply)subgroup I, zinc oxide cement with added fluorides, chlorhexidine and potassium nitrate GC TempAdvantage (American In) subgroup II and zinc oxide cement with silicone aggregate and Temposil Silane (Coltène) subgroup III, were used as luting agents and the load required to detach each of the crowns was determined. A correlation analysis was performed between the force (N) required and the crown-tooth involved area (mm2). Microleakage was assessed using an Olympus stereomicroscope (20X and 32X), under white incident light. By colorimetric contrast, the degree of leakage was defined by the longitudinal penetration of a dye at the tooth-restoration interface. Results: Significant correlation (Pearson: 0.423, P=0.0001) was found between force of detachment and surface. Average values obtained from the detachment force were: group A, 41.09 N; group B, 43.52 N; group C, 41.26 N, without significant differences (P=0.484). The cement factor, subgroup I, 56.87 N; subgroup II 40.75 N; and subgroup III, 28.25 N, was found significant (P=0.0001). Leakage was similar in the three groups, although group B recorded the highest values. Taking into account only the cement factor subgroup II yielded the lowest values, while subgroups I and III recorded similar and somewhat higher values, with an average of 0.94 mm and 1,00 mm, respectively. The combination that showed the lowest penetration was that of group A with subgroup II (average 0.62 mm), while the combination with higher values was seen in group B with subgroup III (average 1.25 mm). Conclusion: Temporary crowns cemented with calcium hydroxide generated the best conditions related to the detachment strength and temporary crowns fabricated using Cerec System with CAD-CAM tecnology, luted with a zinc oxide cement with the addition of fluorides, chlorhexidine and potassium showed, although not significant statistically, better properties in terms of marginal leakage (AU)

Influence of Zingiber officinale Extract on Push-Out Bond Strength of Glass-Fiber Post

Abstract The aim of this study was to evaluate in vitro the influence of 20% glycolic ginger extract on the bond strength of glass-fiber post cemented with etch-and-rinse or self-etching resin cement. Forty-eight bovine roots were standardized (17±0.5 mm) and randomly divided into two groups, according to irrigant used during biomechanical preparation: NaOCl: 1% sodium hypochlorite and GEN: 20% glycolic ginger extract. Root canal was prepared and randomly assigned to one of two subgroups (n=12), according to luting protocol: self-etching (RelyX U200) and etch-and-rinse (RelyX ARC). After 48 h, the roots were sectioned perpendicularly (4 in cervical third and 3 in middle third) and submitted to push-out bond strength test (50 kgf load cell, 1.0 mm/min). Failure mode was analyzed in SEM and stereomicroscopy. Data were analyzed by three-way ANOVA and Tukey tests (p<0.05). ANOVA revealed that there were no significant differences between U200 (2.01±0.17)B and ARC (1.93±0.12)B in GEN group, and at the cervical third for both irrigants, 2.69±0.16A and 2.54±0.17A, respectively. Middle third showed lower bond strength than cervical third, regardless the irrigant. Overall, the cervical third regardless the irrigant employed and the association between NaOCl and ARC, presented better adhesive performance.

Resumo O objetivo deste estudo foi avaliar in vitro a influência do extrato de gengibre 20% na resistência adesiva de pinos de fibra de vidro cimentados com cimentos resinosos convencional ou autocondicionantes. Quarenta e oito raízes bovinas foram padronizadas (17±0.5mm) e aleatoriamente divididas em dois grupos (n=24), de acordo com o irrigante utilizado durante o preparo biomecânico: NaOCl: hipoclorito de sódio 1%; e GEN: extrato glicólico de gengibre 20%. Os canais radiculares foram preparados e aleatoriamente distribuídos em dois subgrupos (n=12), conforme o protocolo de cimentação: autocondicionante (RelyX U200) e convencional (RelyX ARC). Após 48 h, as raízes foram seccionadas perpendicularmente (4 no terço cervical e 3 no terço médio) e submetidas ao teste de resistência adesiva push-out (50 kgf carga, 1.0 mm/min). O modo de falha foi analisado em MEV e estereomicroscopia. Os dados foram analisados pelos testes ANOVA 3-fatores e Tukey (p<0.05). ANOVA mostrou que não houve diferenças significativas entre U200 (2.01±0.17)B e ARC (1.93±0.12)B no grupo GEN, e no terço cervical para ambos os irrigantes (2.69±0.16A and 2.54±0.17A, respectivamente). O terço médio apresentou menor resistência adesiva que o terço cervical, independente do irrigante. Em geral, o terço cervical, independentemente do irrigante empregado, e a associação entre NaOCl e ARC apresentaram melhores desempenhos adesivos.

Effect of cement type on the color attributes of a zirconia ceramic

PURPOSE: This in vitro study evaluated the effects of four different cements on the color attributes of a zirconia ceramic. MATERIALS AND METHODS: 40 zirconia ceramic disk specimens (0.5 mm thickness, 10 mm diameter, 0.1 mm cement space) were fabricated by a computer-aided design and computer-aided manufacturing system. The specimens were divided into 4 groups of 10 specimens and cemented to composite substrates using four different cements including: Glass Ionomer, Panavia F2.0, Zinc Phosphate, and TempBond. The L*, a*, and b* color attributes of the specimens were measured before and after cementation by a spectrophotometer. Additionally, ΔE values were measured to determine color changes for the groups and then compared with the perceptional threshold of ΔE = 3.3. Repeated Measures ANOVA, Tukey Post Hoc, Bonferroni, One-way ANOVA, and One-sample t-test tests were used to analyze the data. All tests were carried out at the 0.05 level of significance. RESULTS: Statistically significant differences were detected in the ΔE values for Zinc Phosphate (P<.0001) and TempBond (P<.0001) groups. However, there were no statistically significant differences in this respect for Glass Ionomer (P=.99) and Panavia F2.0 (P=1) groups. The means and standard deviations of the ΔE values for Glass Ionomer, Panavia F2.0, Zinc Phosphate, and Tempbond groups were 2.11±0.66, 0.94±0.39, 5.77±0.83, and 7.50±1.16 Unit, respectively. CONCLUSION: Within the limitations of this study, it was concluded that Zinc Phosphate and Tempbond cements affected the color attributes of the tested zirconia ceramic beyond the perceptional threshold. However, Glass Ionomer and Panavia F2.0 cements created acceptable color changes.

Correlation between clinical performance and degree of conversion of resin cements: a literature review

AbstractResin-based cements have been frequently employed in clinical practice to lute indirect restorations. However, there are numerous factors that may compromise the clinical performance of those cements. The aim of this literature review is to present and discuss some of the clinical factors that may affect the performance of current resin-based luting systems. Resin cements may have three different curing mechanisms: chemical curing, photo curing or a combination of both. Chemically cured systems are recommended to be used under opaque or thick restorations, due to the reduced access of the light. Photo-cured cements are mainly indicated for translucent veneers, due to the possibility of light transmission through the restoration. Dual-cured are more versatile systems and, theoretically, can be used in either situation, since the presence of both curing mechanisms might guarantee a high degree of conversion (DC) under every condition. However, it has been demonstrated that clinical procedures and characteristics of the materials may have many different implications in the DC of currently available resin cements, affecting their mechanical properties, bond strength to the substrate and the esthetic results of the restoration. Factors such as curing mechanism, choice of adhesive system, indirect restorative material and light-curing device may affect the degree of conversion of the cement and, therefore, have an effect on the clinical performance of resin-based cements. Specific measures are to be taken to ensure a higher DC of the luting system to be used.

Electron Beam Irradiation of Resin Luting Agents - a Cytotoxic Evaluation on Dental Pulp Cells.

Aim: The aim of this study was to evaluate the cytotoxicity of three resin luting agents Rely X luting cement, Rely X luting 2 cement and Clearfil SA luting cement before and after electron beam irradiation. Materials and Methods: Growth and maintenance of cell cultures of human pulp cells was done in Dulbecco’s modified Eagle’s Medium (DMEM). The test samples were divided into two Categories: Irradiated Category and Non-radiated Category. Samples in Irradiated category were exposed to electron beam radiation at 200Gy. Three subgroups of radiated category and non radiated category were made. All the samples were subjected to MTT assay and spectrophotometric analysis and their cytotoxicity was assessed. Statistical analysis was done using t test. Results: Evaluation of Rely X luting Cement showed that radiated samples of powder, liquid and set cements showed decreased cell viability than non radiated samples. In Case of Rely X luting 2 cement, radiated samples showed increased cell viability for Paste A and Paste B samples. But in set material, irradiated samples showed decreased cell viability as compared to non radiated samples. For Clearfil SA luting Cement, Paste B showed increased cell viability for radiated samples. Paste A and Set cement of radiated samples showed decreased cell viability than non radiated samples. Conclusion: In the present study , the increased cytotoxicity of irradiated samples may be due to increase in the release of unbound monomers which may be due to chain breakage after irradiation and a reduction in the cytotoxicity which may be due to the cross linking of unbound monomers during irradiation.

Comparison of effect of desensitizing agents on the retention of crowns cemented with luting agents: an in vitro study

PURPOSE: Many dentists use desensitizing agents to prevent hypersensitivity. This study compared and evaluated the effect of two desensitizing agents on the retention of cast crowns when cemented with various luting agents. MATERIALS AND METHODS: Ninety freshly extracted human molars were prepared with flat occlusal surface, 6 degree taper and approximately 4 mm axial length. The prepared specimens were divided into 3 groups and each group is further divided into 3 subgroups. Desensitizing agents used were GC Tooth Mousse and GLUMA(R) desensitizer. Cementing agents used were zinc phosphate, glass ionomer and resin modified glass ionomer cement. Individual crowns with loop were made from base metal alloy. Desensitizing agents were applied before cementation of crowns except for control group. Under tensional force the crowns were removed using an automated universal testing machine. Statistical analysis included one-way ANOVA followed by Turkey-Kramer post hoc test at a preset alpha of 0.05. RESULTS: Resin modified glass ionomer cement exhibited the highest retentive strength and all dentin treatments resulted in significantly different retentive values (In Kg.): GLUMA (49.02 +/- 3.32) > Control (48.61 +/- 3.54) > Tooth mousse (48.34 +/- 2.94). Retentive strength for glass ionomer cement were GLUMA (41.14 +/- 2.42) > Tooth mousse (40.32 +/- 3.89) > Control (39.09 +/- 2.80). For zinc phosphate cement the retentive strength were lowest GLUMA (27.92 +/- 3.20) > Control (27.69 +/- 3.39) > Tooth mousse (25.27 +/- 4.60). CONCLUSION: The use of GLUMA(R) desensitizer has no effect on crown retention. GC Tooth Mousse does not affect the retentive ability of glass ionomer and resin modified glass ionomer cement, but it decreases the retentive ability of zinc phosphate cement.

Influence of preparation height and luting agent type on crown retention in molars

Aim: Mechanical characteristics of the preparation along with luting agent are significant elements on the maintenance of fixed prostheses. This study aimed at assessing the retention of metal complete crowns luted with two different luting agents under different preparation height. Methods: Forty human third molars were selected and prepared to receive total crowns, and were randomly divided in 4 groups: (1) 5-mm preparation height (PH) and RelyX U100 self-adhesive resin cement (SA); (2) 5-mm PH and zinc phosphate (ZP); (3) 3-mm PH and SA; and (4) 3-mm PH and ZP. Crowns were cast in nickel-chromium alloy. The tensile strength was tested in a universal testing machine. Results: Mean tensile strength values to crown displacement (kgf) and standard deviation were 39.6 (13.0) for group 1; 16.9 (8.1) for group 2; 32.2 (7.9) for group 3; and 10.6(3.2) for group 4. Overall, the crowns cemented with SA presented significantly higher mean tensile strength values than ZP, and the 5-mm PH presented significantly higher mean tensile strength values than 3-mm PH. Conclusions: The self-adhesive resin cement and higher preparation height improved crown retention.