In vitro biocompatibility of novel Au-Pt-based metal-ceramic alloys.
The aim of this research was to evaluate the effect of individual metallic elements within experimental Au-Pt-based metal-ceramic alloys on in vitro biocompatibility. A binary Au-10 at.% Pt alloy (AP10) was designed as a parent alloy. Six ternary AP10-X (X = In/Fe/Sn/Zn) alloys and four quaternary (AP10-In2)-Y (Y = Fe/Sn/Zn) with different compositions were cast into square plates with size 10X10X0.5 mm(3) and subjected to porcelain-firing thermal cycling. A commercial alloy was used as a control. In vitro biocompatibility was investigated using L929 murine aneuploid fibrosarcoma cell line. The test samples and cells were incubated at 37 degrees C in a 5% CO(2) atmosphere for 72 h. Alamar Blue Assay was carried out to determine the respiratory viability of cultures maintained in the presence of the different materials. The cell only control showed significantly higher levels of cell viability than all six of the ternary alloys and two of the four quaternary alloys, (AP10-In2)-Zn2.1 and (AP10-In2)-Sn1.0 (P < 0.05). The quaternary alloys showed slightly higher levels of cell viability than the ternary alloys, with the exception of AP10-Sn0.9. No statistical differences were seen between the ternary and quaternary alloy groups. Acceptable cell viability was observed on the surfaces of all the alloys. (+info)
Effect of a procedural video CD and study guide on the practical fixed prosthodontic performance of Iranian dental students.
Dental students in programs around the world typically pass preclinical courses before entering the clinic and working on actual patients. Since fixed prosthodontics is a preclinical course that requires a great deal of effort, students may experience a substantial amount of stress that may affect their self-confidence and/or clinical performance. In this study, an instructional video CD (VCD) and study guide depicting the step-by-step procedures involved in a metal-ceramic tooth preparation and provisional crown fabrication was prepared. Students at the Faculty of Dentistry, Tehran University of Medical Sciences, Tehran, Iran, were divided randomly into two groups. Group A students trained as usual with live patients, and Group B students were given a copy of the VCD and study guide following a lecture. The students in Group B were encouraged to read the study guide and watch the VCD after live demonstrations. Then, both groups practiced individually on mannequins. At the end of the course, the students completed a sixteen-item questionnaire about their stress level, self-confidence, and knowledge base. The results showed that the students exposed to the extra media performed significantly better on some practical phases, e.g., laboratory procedures. A moderate, insignificant correlation was detected between exposure to media and decreasing the students' stress and self-esteem. We concluded that supplementary teaching aids such as a VCD and study guide may improve the clinical performance of dental students to some extent, but the live demonstration is still preferred by students. (+info)