ِEvaluation of compressive strength in conventional and pack able composite materials Dr. Ghasemi A .,1 Dr. Torabzadeh H .,1 Dr. Moayedi S.2 1 Associate Professor, Department of Operative Dentistry, School of Dentistry, Shahid Beheshti University / MC. Tehran, Iran. 2 Specialist in Operative Dentistry. (Received 6 Nov, 2008 Accepted 26 April, 2009) Abstract Background and Aim : The mechanical properties of composite resin have significant effect on performance and success of a restorative procedure. The aim of present investigation was to evaluate the compressive strength of conventional and pack able composite materials. Materials and Methods : A stainless steel mold of 4 mm in diameter by 6 mm in height was used to fabricate 50 study specimens. The cylindrical specimens were divided in five groups (n=10). The materials used in this study were Alert, Charmfil Plus, P60, Z100 and Spectrum. Following photo polymerization by using Radi Plus light curing unit (SDI Limited), the specimens were stored in distilled water at 37 ○ C for 48 hours. The specimens were subjected to compressive stress using mechanical testing machine (Zwick/Roell) at cross head speed of 0.5 mm/min. One-Way ANOVA and Tukey's Post-hoc tests were employed to determine group differences and the significance level if any of the restorative materials could show significant difference among others. Results : There were significant statistical differences between groups (P < 0.05). Z 100 showed the highest and Charmfil Plus demonstrated the lowest amount of compressive strength. There was no significant statistical difference between Z 100 and P 60, but, differences were significant between Z 100 and other materials. Conclusion : Based on the findings of this investigation, the compressive strength of packable composites was not proving better than conventional composites. Key words : Pack able composite - conventional composite - Compressive strength . Corresponding Author : Dr. Torabzadeh H ., Associate Professor, Department of Operative Dentistry, School of Dentistry, Shahid Beheshti University / MC. Tehran, Iran. e.mail: htorabzadeh@ icdr.ac.ir | 
