Push-Out Bond Strength of Different Esthetic Post: An In-Vitro Study

Abstract

Purpose: This in-vitro study measured push-out bond strength of different posts as function of radicular regions. Statement of Problem: In non-circular or excessively flared root canals, prefabricated posts may not fit well, increasing cement thickness and bubbles at coronal level which may alter its mechanical performance causing impaired post retention. Push-out bond strength test in different radicular thirds of posts will detect location of failure in bonded esthetic posts. Methods: 40 sound extracted human central incisors were used in this study. All teeth were endodontically treated and decoronated 2 mm above CEJ. Then were randomly divided into 4 groups of 10 each regarding type of post used: group 1 (PD): Polymer infiltrated ceramic, Paradigm MZ 100 (3M-ESPE); group 2 (FRC) Fiber post, Postec Plus (Ivoclar Vivadent); group 3 (ZR): Lava Zirconium diox- ide blocks (3M-ESPE); group 4 (CP): Cosmo Post, Zirconium dioxide (Ivoclar Vivadent). All posts were luted with Panavia 21 (Kuraray Noritake, Japan). Push-out tests were performed to evaluate the bond strength of different posts at different radicular regions. Data were statistically analyzed using one way (ANOVA)and Scheffe test made pairwise comparison (α = 0.05). Partially yttrium-stabilized zirconium-oxide post systems were introduced in mid 1990s by various researchers [1,2]. Pure zir- conia material shows polymorphic phase transformation from a cubic, to tetragonal, to monoclinic phase, accompanied by a high volume change when cooling down after sintering, which makes the sintered body unstable. Therefore, dental zirconia material contains 3 to 6 weight % Yttria-stabilized zirconia as an additive to stabilize the ceramic in the tetragonal phase which is usually Different resin luting agents and corresponding bonding sys- tems have been proposed for cementing tooth-colored posts and Results: FRC group recorded the highest mean bond strength value (11.78 ± 0.79MPa). PD group showed higher results (10.10 ± 1.12MPa) than ZR (9.56 ± 0.85 MPa) and CP (7.93 ± 0.89 MPa) and the 2 latter groups were not significantly different from each other p ≤ 0.05. Regardless to post type, it was found that middle region recorded highest bond strength means value, then apical region, meanwhile the lowest mean bond strength values were recorded at cervical regions p ≤ 0.05. Conclusions: Within limitations of this study the following can be drawn: 1- Push-out mean bond strength of different esthetic posts are significantly affected by the type of its materials and manufacturing; FRC recorded the highest bond strength values, ZR and CP showed the least values (P ≤ 0.05). 2- Regardless type of the post, the middle radicular region (as Fiber Reinforced Composite) recorded the highest bond strength then the apical region, meanwhile the cervical region (as Cosmo Post) showed the lowest bond strength values P ≤ 0.05.