The evaluation of compressive strength in three brands of zinc phosphate cement in two different powder/liquid ratios Dr. M. Sahabi * - Dr. N. Homayunfar ** * Assistant Professor of Fixed Prosthodontics Dept., Faculty of Dentistry, Shaheed Beheshti University of Medical Sciences. ** Assistant Professor of Fixed Prosthodontics Dept. Faculty of Dentistry, Rafsanjan University of Medical Sciences. Abstract Background and Aim: 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. Materials and Methods: 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 ºC 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. Results: 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. Conclusion: 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. Key words: Zinc phosphate cement – Compressive strength – Powder / liquid ratio Correspondence Author: Fixed Prosthodontics Dept., Faculty of Dentistry, Shaheed Beheshti University of Medical Sciences. e.mail:masahabi@yahoo.com | 
