Effect of dowel space preparation and composite cement thickness on retention of a prefabricated dowel

Abstract

Paraposts cemented with Panavia 21 OP showed significantly greater retention in oversized dowel spaces compared with dowel spaces prepared with the manufacturers' matched dowel-drill set.

Influence of Oversized Dowel Space Preparation on the Bond Strengths of FRC Posts

“…Therefore, the current design was chosen in agreement with previous studies. [25][26] The wide gap for the size 2 posts in the size 3 post spaces was theoretically calculated to be 124-134 µm at a 5 mm distance from the tip of the post regarding tolerance of the instruments by fabrication; whereas, the cement gap was calculated to be 23-33 µm at the same position for precisely fitting posts. The cement gap of the precisely fitting posts was confirmed to be 35-50 µm after cementation, which had been evaluated in earlier studies for the ER post restoring system.…”

“…In clinical practice, the lower retention of a post cemented into a wider post space might not have a negative effect, as long as the ferrule preparation and retention on the remaining tooth substance stabilize the post retention to withstand chewing forces of approximately 500 N. [37][38] Contrary to previous studies, the dowel space preparation had a significant effect on the bond strengths of the posts. [25][26] Previous studies performed root canal filling before post insertion and used only one composite. [25][26] Hagge and others 25 investigated a cylindrical metal post with Panavia 21 OP, so that different results could be explained by the different post forms and materials.…”

“…[25][26] Previous studies performed root canal filling before post insertion and used only one composite. [25][26] Hagge and others 25 investigated a cylindrical metal post with Panavia 21 OP, so that different results could be explained by the different post forms and materials. However, they also found only cohesive fractures for the precisely fitting posts.…”

“…Therefore, it was hypothesized that a perfect fit between the post and dowel space would no longer be essential. [24][25][26][27] Moreover, using the same build-up composite for the post insertion and for the core build-up in one step was suggested. 28 On the one hand, this would be time-saving regarding the conditioning procedure of the dentin and, on the other hand, a "monobloc" of a post-and-core build-up would offer adequate elastic properties.…”

“…These studies found no negative effect of a wider cement gap, but they did find a significant effect of the composite material as well as the dentin bonding. [25][26][27] The current in vitro study investigated the effect of an oversized dowel space on the bond strengths of FRC posts compared to an exact fitting dowel space using three build-up composites and two commonly used resin cements. The hypotheses examined were that bond strength does not present vast variations according to the width of the gap between the root canal and post and that bond strength increases for FRC posts luted with build-up composites compared with FRC posts luted with resin cements.…”