RESUMEN
Objectives: ceramics have advantages such as optimal esthetics and biocompatibility. However, in the oral environment, they are subjected to high levels of stress due to masticatory forces, saliva, thermal changes and alterations of pH, which increase their risk of fracture. Since replacement of these restorations is costly and time-consuming, composite resin is often used for intraoral repair of these restorations. This study aimed to assess the shear bond strength of two porcelain repair systems by Pulpdent and Ultradent and evaluate the effect of number of silane layers on the shear bond strength
Methods: this invitro experimental study was conducted on 66 porcelain blocks measuring 3×5×8mm. In each kit, samples were randomly divided into three groups of 11. Silane was not used for group one. Groups two and three received one coat and two coats of silane, respectively. After surface preparation, composite was bonded to ceramic surfaces. Data were analyzed using two-way ANOVA
Results: the LSD test showed that application of Ultradent silane significantly affected the shear bond strength [P<0.05] while Pulpdent silane had no such effect [P=0.89]. Application of one layer and two layers of silane was not significantly different [P=0.94]
Conclusion: ultradent ceramic repair kit yields higher shear bond strength at the ceramic-composite interface compared to Pulp dent ceramic repair kit. Use of one or two layers of silane does not make any significant difference with regard to the shear bond strength of ceramic to composite
RESUMEN
Considering to patient's complications with conventional denture in the lower arch, the requirement of a denture with more efficacy and cheaper than conventional ones, is definite. One of the most conventional ones is an overdenture with 2 implant. The purpose of this study was comparison of four types of different attachment systems including two prefabricated and 2 castable attachments. Four groups with 6 numbers of attachments [Superflex ball, locator, castable Ball on bar, castable Bar] were selected. 2 castable groups were casted; these attachments were put on implant fixtures. Then a Cr-Co framework was made. It was put on cast and attachments and an acrylic base was made on this assembly. All the samples were put in universal testing machine and a tension force of 50 Newton was loaded to seprate framework from cast. The tension force was recorded. After data collection, the data were analyzed through SPSS version 16 by One-Way ANOVA and Teukey test. Results showed that retention force of castable ball on bar [35. 31N] was the greatest followed by ball [33.33N, P=0.007], Locator [20.90N] and castable bar [14.74N], respectively [P<0.001]. Castable ball on bar was comparable to ball regarding the retentive force. Therefore this cheap attachment could be used in patients instead of prefabricated one. These attachments have more retention compared to locators which are expensive. When less retention is needed, castable bar can be used, and when more retention is needed, castable ball on bar is recommended