Veneering ceramic to the core is considered to be the weakest part of all-ceramic restorations. Zirconium dioxide, owing to its favorable properties such as high strength, chemical stability, and superior aesthetics, is the material of choice for fabrication of a core. The adhesion between the core and veneering porcelain is based on the same manner in which the connection occurs in metal-ceramic structures. However, the standard procedures for connecting zirconia to hard dental tissues and veneering materials do not achieve the required strength of bonding. The aim of this study was to investigate different surface treatments of the zirconium dioxide ceramic core for achieving highest adhesive bonding values to veneering porcelain. The study was primarily designed to investigate the bonding strength of the veneering porcelain to zirconia with in vitro macro shear bond strength test. The samples of zirconia were divided into four groups of 10 specimens, each according to the treatment of zirconium surface, and the results showed the highest bonding values for samples that were treated with the sandblasted group. AbstractKeywords ► shear bond strength ► zirconium dioxide ► CAD/CAM ► SEM Dent J Adv Stud 2018;6:14-19

Aim The aim of this study was to investigate push-out bond strength of glass fiber posts after various surface treatments and to investigate push-out bond strength at different levels of root (coronal, middle, apical). Materials and Methods Forty extracted teeth were selected for study (maxillary anteriors and mandibular premolars). Roots were sectioned 16 mm from apex, endodontically treated and divided into four groups of 10 each based on surface treatment of posts; Group I (Control Group): No treatment of the post, Group II: Post surface were sandblasted and then treatment with silane coupling agent, Group III: Hydrofluoric acid application on the post surface and then treatment with silane coupling agent, Group IV: Post surface treated with 37% phosphoric acid treatment for 1 minute. Posts after various surface treatments were luted. Roots were then cut into three sections coronal, middle, and apical. The push-out test was done to assess push-out bond strength. The data obtained were statistically analyzed. Results Hydrofluoric acid and silane coupling agent treatment had little effect on the bond strength of post. Sandblasting and silane coupling agent was proven to be more effective and improved push-out strength of glass fiber posts followed by phosphoric acid group. Conclusion It was concluded that sandblasting followed by silane coupling agent showed highest bond strength in all parts of the root compared with other surface treatments. Highest push-out strength was found at the coronal level of the root followed by middle and apical level.