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.

Push-out bond strength of different translucent fiber posts cemented with self-adhesive resin cement.

PURPOSE: Evaluate the bond strength of different translucent fiber posts in the cervical, middle, and apical root thirds cemented with self-adhesive resin cement. MATERIALS AND METHODS: Sixty single-rooted teeth were randomly divided into five groups according to the fiber post used: Reforpost (opaque [control]), exacto, white post, radix, and Macro-Lock Illusion X-RO. The roots were subjected to chemomechanical preparation and cemented with self-adhesive resin cement. The teeth were sectioned into slices of the different root thirds and tested for bond strength (push-out). Two-way analysis of variance and Bonferroni test were used to verify statistical differences between groups (P < 0.05). RESULTS: No significant difference between the root thirds was detected (P > 0.05). However, the performance of the posts demonstrated a significant difference (P < 0.05). RDX had a lower performance in the apical third (P < 0.05). The other fiber posts had the same performance irrespective of the root third evaluated. The predominant failure pattern was adhesive between resin cement and root dentin. CONCLUSION: In general, the different translucent fiber posts showed the same performance. Yet, translucent fiber posts did not show superior bond strength compared with the opaque fiber post in any of the root thirds evaluated.

Mechanical reliability of air-abraded and acid-etched bonded feldspar ceramic.

OBJECTIVES: This study investigated the effect of surface treatment (air-abrasion with alumina or hydrofluoric acid-etching) on feldspar ceramic mechanical strength and initial reliability (24h) before/after adhesive luting. METHODS: Ceramic discs (VITA) were tested as monolithic specimens (Acid; Abrasion), luted bilayers (Acid+luting agent; Abrasion+luting agent), or untreated (Control). Luted groups were coated using resin-based agent (RelyX Veneer, 3M ESPE). Biaxial flexural test with ball-on-ring setup was carried out (n=30). Biaxial flexural strength (σbf, MPa), characteristic strength (σ0, MPa), and Weibull modulus (m) were calculated for axial positions z=0 (ceramic surface) and z=-t2 (luting agent surface). For each condition, 95% confidence intervals were calculated. Scanning electron microscopy was used for topography and fractography analyses. RESULTS: At z=0, σbf and σ0 of luted specimens were higher than of monolithic specimens for both surface treatments. Groups Acid and Abrasion had lower σbf and σ0 than Control. Group Abrasion had poorer mechanical strength. Similar structural reliability was observed for all conditions except for the group Abrasion+luting agent, which had lower m than all other groups. At z=-t2, no significant differences between luted groups were observed for mechanical strength and reliability. A more irregular surface topography with more sharp angles was left by air-abrasion than etching. Monolithic specimens failed from surface pores at the tensile area, whereas failure in luted specimens originated from pores below the resin-ceramic interface. SIGNIFICANCE: Air-abrasion yielded lower mechanical strength and initial reliability than acid etching. Presence of a resin-based luting agent layer bonded to ceramic significantly increased its mechanical strength.

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.

The Effect of Luting Agents and Ceramic Thickness on the Color Variation of Different Ceramics against a Chromatic Background.

OBJECTIVES: The aim of this study was to assess the influence of various ceramic thicknesses and luting agents on color variation in five ceramic systems. METHODS: Fifteen disc-shaped ceramic specimens (11 mm diameter; shade A3) were fabricated with each of the six veneering ceramics tested, with 1, 1.5, or 2 mm thickness (n=5). Resin composite discs (Z-250, shade C4) were used as bases to simulate a chromatic background. The cementation of the veneers was carried out with an opaque resin-based cement (Enforce, shade C4), a resin-based cement (Enforce, shade A3), or without cement (C4, control group). Color differences (ΔE*) were determined using a colorimeter. Three-way ANOVA was used to analyze the data, followed by a Tukey post-hoc test (α=.05). RESULTS: The L*a*b* values of the ceramic systems were affected by both the luting agent and the ceramic thickness (P<.05). In general, there was no difference between the control group and the group using the resin-based cement. The use of an opaque luting agent resulted in an increase of the color coordinates a*, b*, L*, producing differences in ΔE* values for all ceramics tested, regardless of the thickness (P<.05). For the 2-mm thick veneers, higher values in the color parameters were obtained for all ceramics and were independent of the luting agent used. CONCLUSIONS: The association of 2-mm thickness with opaque cement presented the strongest masking ability of a dark colored background when compared to a non- opaque luting agent and the other thicknesses tested.

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.

Avaliação da resistência de cisalhamento na união de diferentes agentes cimentantes / Shear bond strength of differet luting agents

O objetivo deste estudo foi avaliar a resistência de cisalhamento de três diferentes marcas de agentes cimentantes: Comspan Opaque, Panavia Ex e Panavia 21. O ensaio de cisalhamento das amostras foi realizado em uma máquina de ensaio universal. Os dados obtidos foram submetidos à análise de variância seguida pelo teste de Tukey (p<0,05). Pode-se observar pelos resultados que a resina Comspan Opaque apresentou resultados adesivos inferiores em relação às resinas Panavia Ex e Panavia 21, sendo estes estatisticamente significativos. As resinas Panavia Ex e Panavia 21 não apresentaram diferença estatisticamente significante

The aim of this study was to evaluate the shear bond strength of three different brands of luting agents: Comspan Opaque, Panavia Ex and Panavia 21. Shear bond test was performed in a universal testing machine. Data were analysed by Analysis of variance and Tukey test (p<0.05). Comspan Opaque resin showed statistically lower bond strength in comparison to Panavia Ex and Panavia 21. Panavia Ex and Panavia 21 resins presented similar shear bond strength