Therefore, the hypothesis was rejected. The reason for this could be attributed to the luting cement (Panavia F2.0) used,
as it adheres to both the tooth structure and the crown substrate mechanically and chemically. Also, the use of silane-coupling agents as adhesive promoters, capable of forming chemical bonds to organic and inorganic surfaces, contributes further to the adhesion of the cement to the ceramic surfaces, thereby the retention. Even though higher mean retention values were recorded with tribochemical silica coating Gamma-secretase inhibitor and silanization, the results were not significant as compared to that of HF acid-treated groups. Tribochemical silica coating and silanization increases the silica content on the ceramic surface and enhances the adhesion between the ceramic surface
and the luting cement. On the other hand, the obtained microporosity increases the surface area and makes micromechanical interlocking of the resin possible. In spite of that, conditioning method did not affect the retention results significantly. A previous clinical study with zirconia ceramic, where adhesion of the resin cement is much inferior GSK3235025 mouse compared to glassy matrix ceramics, has also reported that silica coating was not necessary for the cementation of zirconia;33 however, glass matrix ceramics cannot be compared with oxide-based ceramics such as zirconia in terms of cementation protocols. Zirconia is an inherently stronger material than glass GNE-0877 ceramics, and therefore the latter needs to be adhesively cemented to improve their tensile strength. Although no clinical
report exists in the dental literature regarding the hazardous consequences of HF acid gel, caution should be exercised when handling this material. Based on the insignificant differences between the two surface conditioning methods, and considering the possible hazardous effects and the non-significant differences between HF acid etching and silica coating, clinicians may consider the use of the latter for safer application; however, after both conditioning methods, silane application is compulsory,12,21 and silica coating requires additional armamentarium in the dental practice, adding to the cost of this conditioning system. In this study, the coronal length of the preparations was kept at 3 mm, similar to a previous study.33 This coronal length could be considered as the minimum where mechanical retention may be impaired. Longer preparations or smaller taper angles, where available, may contribute to better retention. Nevertheless, both factors could be compensated for with the adhesive luting cement tested. Because no aging conditions were implemented, the results represent early clinical failures. Further in vitro studies are needed using a similar methodology but with long-term storage in an aqueous medium to investigate whether the retention of such crowns would be affected.