Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 10 1 2013 01 30 94 102 Farideh Geramipanah Associate Professor, Dental Implant Research Center, Department of Prosthodontics, Faculty of Dentistry, Tehran University of Medical Sciences, Tehran, Iran. Susan Mir Mohammad Rezaei Saman Fallahi Sichani Babak Fallahi Sichani Leyla Sadighpour 2015 10 16 The effects of closely adapting a prefabricated fiber to the post space remain unknown. The purpose of this study was to quantify the microleakages of a custom adapted fiber-reinforced post, a prefabricated quartz fiber post and a cast post using nondestructive methods.Sixty-five extracted human premolars were endodontically treated and randomly divided into three groups (n=15), which were restored using a cast post-and-core, a custom adapted fiber post (Refropost) with a microhybrid microfiller resin composite (Gradia), or a prefabricated quartz fiber post (DT light post) and two groups of control (n=10). All groups were cemented using a dual polymerizing resin cement (Panavia F2.0). A composite core (Z100) was used for the fiber posts. The microleakage was calculated for the experimental and control groups before and after thermal cycling and cycling loading using a radiotracer solution (thallium 201 chloride) and a gamma counter device. Data were subjected to statistical analysis of ANOVA and Tukey HSD at significant level of P< 0.05.Significantly lower microleakage values were found for the cast post-and-core (mean value =16.04 ×10(4)) and custom adapted fiber post groups (mean value=14.36×10(4)). Thermal cycling and cyclic loading had no significant effect on the microleakage value of any tested group.Post systems with improved adaptation showed similar microleakage to casting posts. https://fid.tums.ac.ir/index.php/fid/article/view/697 https://fid.tums.ac.ir/index.php/fid/article/download/697/672