Effect of cement types and timing of cementation on the retentive bond strength of fiber posts

To evaluate the effect of early versus delayed post space preparation and cementation and the types of cement on the retention of fiber posts in canals obturated using an epoxy resin sealer. Seventy-two extracted single-rooted teeth with straight root canals were decoronated and obturated with gutta-percha and an epoxy resin sealer (AH26). Post spaces were prepared to a depth of 8 mm and 1.5 mm diameter. Parallel-sided, prefabricated fiber posts were used. The teeth were distributed into two groups (36 in each), according to the period elapsed between canal obturation and post cementation (Group 1: cementation after 24 hours and Group 2: cementation after 2 weeks). Each group was further subdivided into three groups (n = 12) according to the cement types (RelyX Unicem, ParaCore and Variolink II). Each specimen was vertically secured in the universal testing machine and was subjected to a pull-out test. Data were statistically analyzed using two-way analysis of variance. The mean post bond strength in the ParaCore and Unicem groups was significantly higher than that in Variolink II group. There was no significant difference between post bond strength values achieved after 24 hours and those achieved after 2 weeks for the ParaCore and Unicem groups (P = 0.538). However, posts cemented with Variolink II showed an increase in retention after 2 weeks (P < 0.05). There was no influence of time interval between canal obturation and post cementation after 24 hours and 2 weeks on the retentive strength of posts luted with ParaCore or Unicem cements.