evaluation of compressive strength in three brands of zinc phosphate cement in two different powder/liquid ratios

This study was conducted to evaluate the compressive strength of 3 brands of Zinc Phosphate Cements determining the influences of eye estimated [rough measurement] of powder/liquid ratios on the compressive strengths of these cements. The three tested Zinc phosphate cements were Hoffmann's [Harvard Dental GmbH], DeTrey Zinc [Densply] and Ariadent [Asia Cherri Teb]. The specimens were divided into 6 groups, each one containing 10 samples. These samples were prepared according to ISO 9917 [2003] and stored in distilled water at the temperature of 37 °C for 24 hours. The compressive strengths of samples were measured with the Zwick testing machine. The ANOVA and Tukey statistical tests were used to identify the significant differences between these groups. There were significant differences between compressive strengths of cements prepared with manufacturer suggested mixing ratios and clinically used [eye estimated] ratios. The least compressive strength was recorded for Ariadent samples with clinical mixing ratio and the highest was recorded for Hoffmann's samples with manufacturer's suggested ratio. In clinically used ratios, Hoffmann's cement had the highest compressive strength. The differences between the strengths of manufacturer suggested mixing ratios and clinically used ones were the most in DeTrey Zinc cement

[Fabrication of implant-supported ear prosthesis: report of a case]

Restoration of facial lesions has been always difficult for prosthodontists. Extraoral facial prosthesis are faced with apparent limitations such as base removable tissue, lack of large-sized prosthesis and intolerance by the patients. The use of implants may lead to a decrease in these limitations. The implant-induced retention can replace the largesized prosthesis in removable tissue bases and then, the attention may be focused on prosthesis esthetics only. The present study reports a case of implant - supported ear prosthesis with trauma history referring to Removable Prosthodontics Department of Dental School, Shaheed Beheshti University of Medical Sciences

[Prefabricated posts: a literature review]

Restoring endodontically treated tooth with prefabricated post is a well accepted technique with a long history. This article reviews and classifies various prefabricated posts. Different types of prefabricated posts are available in the market now. These posts are different from each other in installation method, geometric form, surface configuration and material. Each type has it's own advantages and disadvantages. Previously, only metal prefabricated posts in different designs, shapes and surfaces were fabricated by manufacturers. With increasing demand for esthetic restorations, like all ceramic restorations and also for using bonding systems more and more, the need for nonmetallic posts is increased, pushing manufacturers to fabricate ceramic and fiber-reinforced resin posts. A dentist must know about characteristics, advantages and disadvantages of different posts and choose the most suitable type for each case