Absract:
An in-vitro experimental study was conducted to compare retention and deformity of three different RPD clasp materials (poly ether ether ketone, nickle titanium alloy, and acetal materials) with conventional cobalt chromium alloy;material and methods; A total of (56) RPD's Aker clasps were divided into four equal main groups (n=14) according to type of clasp materials; poly ether ether ketone (PEEK), nickle titanium (Ni/Ti), acetal, and cobalt chromium (Co/Cr) materials. All clasp samples in each group were used for retention test and deformity test. Results: One way ANOVA test and Pairwise comparison between each 2 groups using Post Hoc Test were used for retention and deformity tests at base line and after 730 , 1460 ,2190 and 2920 cycles revealed that metallic (Co/Cr) clasps ofer greater retentive forces followed by(Ni/Ti) than non metallic (PEEK) then acetal resin clasps with differences considered as Statistically significant as p ≤ 0.05 at all testing loading cycles. also(Co/Cr) clasps ofer greater deformity value followed by(Ni/Ti) than non metallic (PEEK) and acetal resin clasps with differences considered as Statistically significant as p ≤ 0.05 nearly at all testing loading cycles except at 2920 cycles where non-metallic (PEEK) followed by acetal resin claspsofer greater deformity than metallic(Co/Cr) clasps then(Ni/Ti) with differences considered as Statistically significant as p ≤ 0.05.Conclusion within limitations of this study it is better to use PEEK clasps for esthetic reasons; and (Co/Cr) clasps for retention reasons.