RESUMEN
OBJECTIVE: The objective of this study was to determine the effect of Cosmopost's two different surface treatments (sandblasting and silica coating) on persistence to various core materials using push-out test set-up. MATERIAL AND METHODS: A total of 30 Cosmoposts was used in this study. Cosmoposts were divided into three groups (10 samples each) according to the post-surface treatment received. Every category was additionally subdivided into two subgroups according to the type of core material (n = 5 samples). A specially designed copper mold was used for construction of different core materials with standardized dimensions around the posts, in such a way to ensure that the posts will be centralized. Surface roughness was estimated for all Cosmoposts, following different surface treatments using SEM. Cylindrical cores were fabricated of either composite resin or heat-pressed zirconia-containing glass-ceramic (IPS Empress Cosmo, Ivoclar Vivadent). Following the construction of different Core materials, samples were subjected to push-out test set-up to Evaluate the impact of various treatments on post/core bond strength. Data were collected, tabulated and statistically analyzed. SEM was performed on Cosmoposts following debonding of different post/core samples to determine their mode of failure. RESULTS: Results of push-out bond strength revealed that core material, surface treatment and the interaction between the two variables using Two-way ANOVA had a statistically significant effect on mean push-out bond strength. Regarding the effect of type of core material on Push-out bond strength, results showed that IPS Empress Cores showed statistically significant higher mean push-out bond strength to Cosmopost (36.4±9.7MPa) than composite cores (15.8±2.5 MPa). CONCLUSION: Within the limitations of this study, direct heat-pressed ceramic core was more beneficial for zirconia post buildups, than Composite Cores, since they provided higher bond strength. Thanks to a double improvement: increase in fracture resistance and retentive capacity to post. Also, Tribochemical Silicacoating technique was proved to be more effective in Cosmopost treatments than sandblasting technique.
RESUMEN
AIM: This study aimed to evaluate the bond strength between esthetic posts and dentin at different regions of the root canal in passive mode or push-out active mode. METHODS: Twenty extracted human bicuspid single canal teeth were used in this study. Teeth were sectioned below the cement-enamel junction. The roots of teeth were endodontically treated. Glass fibre posts (Glassix plus, Harald Nordin SA, Switzerland) and zirconia posts (Zirix, Harald Nordin) were then adhesively luted with total-etch (Variolink N, Ivoclar Vivadent, Schaan, Liechtenstein) and self-adhesive (Multilink Speed, Ivoclar Vivadent) resin cement. The roots were divided into two main groups of 10 samples each, according to the type of post used. Each group subdivided into 2 subgroups of 5 samples each, according to the type of cement used. The specimens were transversally sectioned into three slices of 2 mm thickness to perform the push-out test. The push-out tests were performed at crosshead-speed, 0.5 mm/min). Failure modes were evaluated using a scanning electron microscope at magnification (x 150). RESULTS: The results revealed that push-out bond strengths were significantly affected by the type of luting agent and the type of post (P ≤ 0 .05). The mean push-out bond strength values for fibre post were significantly higher than those for zirconia post independent of the luting strategy used. The score values of total-etch adhesive resin cement were higher than those for self-adhesive resin cement irrespective of other variables. Regarding the effect of the root segment on push-out bond strength, results revealed that bond strength decreased from the coronal to the apical section. The cement-dentin interface found to be the weakest part of the root-cement-post unit. CONCLUSION: Glass fibre posts revealed better results in all root third when they adhesively luted with total-etch or self-etch adhesive resin cement and provided significantly increased bond strength compared to the zirconia posts.
