PUSH-OUT BOND STRENGTH OF DIFFERENT ESTHETIC POSTS AN IN VITRO STUDY

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.
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 dioxide 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).
Results: FRC group recorded the highest bond strength (11.78±0.79MPa). PD group showed higher results (10.10±1.12MPa) than ZR(9.56±0.85MPa) 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 bond strength values were recorded at cervical regions p≤0.05.
Conclusions:1- Push-out bond strength of different esthetic posts are significantly affected by the type of its materials and manufacturing; FRC recorded the highest bond strength values,PD recorded intermediate values, ZR and CP showed the least values with no significant difference between them.(P≤0.05) 2-Regardless to type of post , the middle radicular region recorded the highest bond strength then apical region, meanwhile cervical region showed the lowest bond strength values P≤0.05.