RESUMEN
OBJECTIVES: To evaluate the effect of immediate versus delayed post space preparation and cementation on the retention of different types of fiber posts in canals obturated with an epoxy resin sealer. METHODS: Sixty-eight single-rooted human teeth were decoronated and the root canals were shaped with rotary instruments and obturated with gutta-percha and an epoxy resin sealer. The teeth were divided into four experimental groups according to the different times of post space preparation and cementation: immediate (group 1), 24h (group 2) and 1 week (group 3) after root canal filling. Control group (group 4) with no root canal obturation was included. Two teeth were randomly selected from each group for SEM examination. Each group was further divided into three subgroups of five teeth each (n=5), according to the type of post and the materials used for luting the posts. A push-out test was performed and differences among experimental groups were analyzed with two-way ANOVA and Tukey test (alpha=0.05). RESULTS: Interfacial strength values achieved in group 1, where an immediate cementation was performed, were significantly lower (p<0.05) than those in group 2 and group 3 in which post cementation was performed 24h or 1 week after the root canal filling. Post type affected post retention, FRC Postec and DT Light Post posts achieved higher interfacial strengths than ENA Post (p<0.05). SEM examination revealed a more conspicuous presence of sealer remnants on the walls of immediately prepared post spaces. CONCLUSIONS: Delayed cementation of fiber post resulted in higher retentive strengths irrespective of the post type.