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Abstract
The bond between core material and the post should be strong and durable to withstand functional loads and thermal changes in oral cavity. Laboratory evaluation of the tensile bond strength between core material and post can be a useful guide to the clinician to determine which post/core combination to be used.
This study was designed to evaluate in vitro the effect of thermocycling on the retention of two different core materials supported by three different post types and to determine the type of fracture which occurred. A total number of sixty posts were used in this study, they were grouped according to post type into three groups : group I (ceramic post), group II (carbon fiber post) and group III (metal post) (n = 20). Each group was further subgrouped according to core material used into two subgroups: subgroup A and subgroup B (n = 10), in subgroup A glass ionomer cores were built up over the heads of ten posts of each group and in subgroup B composite cores were built up over the heads of the other ten posts of each group, while the post heads at the center of the cores, thus was achieved by a specially designed post holder for each type of post. After complete setting of the glass ionomer and composite core materials, the prepared samples were removed from the post holders.