Radiopacity and Chemical Assessment of New Commercial Calcium Silicate-Based Cements / Radiopacidad y Evaluación Química de Cementos Comerciales en Base a Silicato de Calcio

ABSTRACT: The aim of the study was to evaluate the chemical composition and radiopacity of new calcium-silicatebased cements. Discs of 10 mm x 1 ± 0.1mm were prepared of BiodentineTM, TheraCal, Dycal and GC Fuji IX (n=5). The samples were radiographed directly on an PSP occlusal plate adjacent to an aluminium step wedge. The radiopacity of each specimen was determined according to ISO 9917/2007. Statistical analyses were carried out using ANOVA and Tukey's test at a significance level of 5 %. The chemical constitution of materials was determined by scanning electron microscopy (SEM) and energy dispersive x-ray element mapping. The radiopacities of the materials in decreasing order were: GC Fuji IX (3.45 ± 0.16 mm), Dycal (3.18 ± 0.17), BiodentineTM (2.79 ± 0.22), and TheraCal (2.17 ± 0.17). TheraCal showed the lowest radiopacity compared to the other materials, followed by BiodentineTM. Dycal and GC Fuji IX radiopacity values did not present significant statistical differences. Scanning electron microscopy and energy dispersive X-ray analysis revealed the presence of zirconium in BiodentineTM; and strontium, barium and zirconium in TheraCal as radiopacifying elements. The new calcium silicate cements present distinctive chemical composition. BiodentineTM contains zirconium as a radiopacifying element and has higher radiopacity values than TheraCal, which contains barium and strontium as radiopacifiers.

RESUMEN: El objetivo de este estudio fue evaluar la composición química y la radiopacidad de nuevos cementos en base a silicato de calcio. Discos de 10 mm x 1 ± 0,1 mm fueron preparados con BiodentineTM, TheraCal, Dycal y GC Fuji IX (n=5). Las muestras fueron radiografiadas directamente en una película PSP oclusal adyacente a una cuña escalonada de aluminio. La radiopacidad de cada espécimen fue determinada de acuerdo a la norma ISO 9917/ 2007. Se realizaron los análisis estadísticos con las pruebas ANOVA y test de Tukey con un nivel de significancia de 5 %. La constitución química de los materiales fue determinada con microscopía electrónica de barrido y con mapeo por análisis con dispersión de energía de rayos X. La radiopacidad de los materiales en orden decreciente fue: GC Fuji IX (3,45 ± 0,16 mm), Dycal (3,18 ± 0,7 mm), BiodentineTM (2,79 ± 0,22 mm), y TheraCal (2,17 ± 0,17 mm). TheraCal mostró la menor radiopacidad comparada con los otros materiales, seguido de BiodentineTM. Los valores de radiopacidad de Dycal y GC Fuji IX no presentaron diferencias estadísticas significativas. Los análisis de microscopía electrónica de barrido y mapeo por análisis con dispersión de energía de rayos X revelaron la presencia de zirconio en BiodentineTM; y de estroncio, bario y zirconio en TheraCal, como elementos radiopacos. Los nuevos cementos en base a silicato de calcio presentan una composición química distintiva. BiodentineTM contienen zirconio como elemento que provee radiopacidad y tiene mayor valor de radiopacidad que TheraCal, el cual contiene bario y estroncio como agente radiopaco.

Influence of ceramic material, thickness of restoration and cement layer on stress distribution of occlusal veneers

Abstract The aim of this study was to evaluate stress distribution in an occlusal veneer according to the restorative material, restoration thickness, and cement layer thickness. A tridimensional model of a human maxillary first molar with an occlusal veneer preparation was constructed using a modeling software of finite element analysis. The model was replicated 9 times to evaluate the factors: restoration thickness (0.6, 1.2, and 1.8 mm) and cement layer thickness (100, 200, and 300 μm). Then, each model received different restorative materials (High Translucency Zirconia - [YZHT], Lithium Disilicate - [LD], Zirconia Reinforced Lithium Silicate - [ZLS], Feldspathic - [F], and Hybrid Ceramic - [HC]), totaling forty-five groups. An axial load (600 N) was applied on the occlusal face for static structural analysis. Solids were considered isotropic, homogeneous, and linearly elastic. Contacts were considered perfectly bonded. Fixation occurred in the dental root and a mechanical static structural analysis was performed. Descriptive statistical analysis and one-way ANOVA (α =10%) were performed for tensile stress peak values in the restoration and cement layer. The difference between groups was compared using the Tukey's test with 10% significance to match the percentage of the mesh convergence test. According to the results, the cement layer thickness did not influence stress distribution in the restoration (p ≥ 0.10). The thicker the restoration, the higher the tensile stress concentration in the restoration. The graphs showed higher stress concentration in the YZHT, followed by LD, F, ZLS, and HC. Also, the restorative material influenced stress concentration on the cement layer, which decreased according to the sequence HC>YZHT>ZLS>LD>F. HC stood out for causing the least stress concentration in the restoration. Cement layer thickness did not interfere in the mechanical performance of the restorations.

Evaluation of biocompatibility of Targis Dentin and Artglass by using subcutaneous implantation test.

Introduction: Biocompatibility of a crown-bridge material is as important as its physical and mechanical properties. It is also one of the most important factors for the long-lasting clinical success of that restoration. It directly contacts the vital prepared tooth and that is the reason it has to be nontoxic to the local tissues, such as the pulp, gingiva, or the rest of the body. Materials with different physical properties are used in the conventional fixed prosthodontic restorations. Recently, metal-free systems that are reinforced with fibers have been improved for crown and bridge restorations. These new composite systems have the advantages of both ceramic and polymer chemistry. Materials and Methods: In this research, biocompatibility of two ceramic-polymer-based prosthetic materials (Targis Dentin® and Artglass Dentin® ) was studied using a subcutaneous implantation test on rats. Initially (15 th day) mild inflammatory reactions were observed in tissues, which directly contacted the Artglass, Targis, and control tubes. These probably originated from the surgical traumas. After the 90th day of implantation, these reactions resolved and healthy, well-organized fibrous connective capsules were seen around the implants. Results: Initially (15 th day) mild inflammatory reactions were observed in tissues, which directly contacted the Artglass, Targis, and control tubes. These probably originated from the surgical traumas. After the 90 th day of implantation, these reactions resolved and healthy, well-organized fibrous connective capsules were seen around the implants. Conclusion: At the end of the study, according to the FDI and ISO-7405 standards, Targis and Artglass indicated biocompatibility with the subcutaneous connective tissue of the rat.

Materiales restauradores con desprendimiento de fluoruro y la reincidencia de caries: parte I: antecedentes / Fluoride releasing restorative materials and caries re-incidence: part I: background

El desarrollo de los materiales dentales restauradores con desprendimiento de fluoruro y la prevención de la reincidencia de caries, depende de muchos factores y no necesariamente sólo del efecto terapéutico del fluoruro sobre la estructura del diente. La relación de estos materiales con la presencia de caries secundaria es revisada en este artículo, así como también la evolución de la incorporación de fluoruro a distintos materiales dentales restauradores.

Materiales restaurativos anticariogénicos / Anticariogenic restorative materials

Existen diferencias claras en el funcionamiento de liberación de flúor entre los cementos de ionómero de vidrio y compómeros. Sin embargo, la diferencia asociada con algunos de estos materiales con respecto a la inhibición de caries no es aún muy clara. Por otra parte, la adhesión de resina a los cementos de ionómeros de vidrio y la adhesión de ácidos a las resinas compuestas hace imposible distinguir entre resinas compuestas, compómeros y ionómeros de vidrio, ya que todos estos presentan liberación de flúor. La liberación óptima en una restauración dental depende de varias condiciones incluyendo la flora oral, saliva, dieta, contenido de mineral en los tejidos dentales y sellado marginal de la restauración. Actualmente, estudios in vitro e in vivo sugieren que los materiales que se comportan similar a los cementos de silicato en su reacción de fraguado y sus características de hidratación, funcionarán de la misma manera como inhibidores de caries. Sólo hasta que la liberación de flúor de las restauraciones dentales pueda ser cuantificada en óptimas condiciones, los estudios clínicos a largo tiempo son la mejor prueba de inhibición de caries. Cerca ya de un siglo de descubrimientos clínicos soportan el efecto anticariogénico de los cementos de silicato. Este artículo revisa la liberación de flúor y la acción anticariogénica de los materiales restaurativos usando como ejemplo el mecanismo de prevención de caries secundaria del cemento de silicato. El comportamiento de nuevos materiales será comparado a los cementos de silicato para predecir su efecto anticariogénico

Avaliaçäo clínica de restauraçöes à cimento de silicato / Clinical evaluation of silicate cement restorations

O autor realizou trabalho clínico de um ano de observaçäo em 27 pacientes, nos quais foram realizadas restauraçöes com cimento de silicato, que foram avaliadas em relaçäo aos aspectos: cor, descoloraçäo marginal, forma anatômica e cárie e classificaçäo de melhor para pior restauraçäo. As restauraçöes foram agrupadas de acordo com o tratamento dado, ou seja, tempo de permanência da tira de matriz (3 e 10 minutos) e tipo de agente protetor superficial (verniz cavitário e selante). A análise estatística dos resultados mostrou que näo existe diferenças estatisticamente significantes entre as variáveis utilizadas, mostrou ainda que os aspectos de cor, descoloraçäo marginal e forma anatômica, foram consideráveis nos primeiros seis meses, mas que nos seis meses seguintes os referidos aspectos praticamente näo sofreram modificaçöes...