METHODS: 17 extracted human permanent maxillary central incisors were endodontically treated following the standard protocol. 17 fiber reinforced composite post had been fabricated and adapted to the prepared parallel root canals. A light body poly vinyl siloxane (EXAMIX NDS, Japan) impression material was inserted into the root canals followed by the post. A digital scale was used to measure the weight of the remaining material that filled the gap between the post and the canal wall. The adaptation was indicated by the weight difference before and after impression material insertion. The same procedures were repeated with 17 cast post-and-core in the same teeth specimens.

RESULT: The mean difference for the weight of the material within the group was statistically significant (P-value <0.001) with the value of 6.1mg(± 2.7mg) for cast metal post and 6.4mg(± 2.7mg) for fiber reinforced composite post. However, the mean difference was not statistically significant when compared with both materials (P-value>0.05).

Materials and Methods: Sixty-eight human maxillary permanent incisors were divided into four groups. Each specimen was endodontically treated with step-back technique and prepared for each post system according to experimental groups, subsequently cemented in the canal. Composite resin cores were built and laboratory fabricated metal crowns were cemented. All specimens except those in the control group were subjected to thermal cycling. All groups were subjected to gradual loading from 0N-50N for 100 cycles. Specimens were sectioned transversely and the depths of dye penetration along the post were measured. Data were entered in SPSS ver. 22 and analyzed using two-way ANOVA test.

Results: There was no significant difference in marginal dye penetration between each group (p-value>0.05). However, there was a significant difference in percentage of marginal dye penetration between all groups (p-value<0.05); post-hoc comparison showed significant difference between Fiber White and Control groups (p-value=0.009).