Fracture load of monolithic zirconia crowns prepared with different margin designs and cemented by different resin luting cements

Abstract

Zirconia has seen widespread use in recent years because of its superior mechanical qualities. Due to the opaque tint of the zirconia core, the veneering layer was applied to improve the aesthetics of the restoration.[2,3] But this could also lead to the veneering layer's failure (cohesive or sticky).[4] By skipping the veneering porcelain layer, monolithic zirconia restorations can be used successfully in a variety of clinical settings.[5] Since the clinical guidelines are still based on those for all-ceramic and metal-ceramic crowns, the suggestion of the margin design for high strength ceramic materials, such as zirconia, is not obvious.[.6] Monolithic zirconia restorations are effective in clinical settings, particularly with patients who have a constrained interocclusal distance and who have a high occlusal load.[7,8] Thus, using monolithic high-strength ceramics can lessen the intrusive preparation of teeth[9,10]. Due to advancements in dental technology that allowed for the creation of precise restorations utilizing computer-assisted design (CAD) and computer-assisted manufacturing (CAM) procedures, zirconia restorations have become increasingly popular. [11] The introduction of transparent zirconia into dental practices recently has challenged the material's natural aesthetic look because it can be employed as a monolithic, highly translucent zirconia repair only in the aesthetic zone. This material, which exhibits exceptional levels of strength, is being used more frequently in dental offices, particularly for the chair-side manufacturing of zirconia restorations. However, the cause of the zirconia crown's failure has been identified. The crown margin has reportedly been the source of fracture during clinical use [12]. The margin is an important part of the restoration that is tightly suited to the specific finishing region of the prepared abutment. The quality of the restoration margin is strongly tied to the method used to prepare the tooth and the process used to fabricate the restoration. The doctor can digitally create a well-contoured restoration with a good marginal fit and the right emergence profile thanks to excellent clinical skills and methods. The peripheral portions, which have little thickness, typically cause the crown to break easily [13]. It's possible that the margin design and thickness have something to do with the failure that started in the zirconia restoration's margin. [13]. Numerous studies have been conducted to determine how the margin design affects the occlusal thickness and wall thickness of zirconia restorations in relation to load-bearing capacity [12, 14–15]. By applying an occlusal load, either longitudinally or obliquely, to anatomical crowns until fracture, some studies into the fracture resistance of all ceramic restorations were conducted. The results showed that the failures of ceramic restorations were regularly indicated in the patterns by a compressive curl, hackle, wake hackle, twist hackle, and arrest lines, which helped to distinguish the crack propagation pattern and the origin. As a result, the design of the margins in restorations significantly affects the ceramic restoration's ability to resist fracture. However, it is still undoubtedly unclear how the design and restoration configuration will affect the fracture properties of a high-translucency monolithic zirconia (HTMZ) restoration. Shape of the prepared tooth, kind of all-ceramic crown system used, thickness of the porcelain crown, flaws in the porcelain, and luting cement systems are some of the aspects that affect a ceramic crown's strength.[16-21] Zinc phosphate, zinc polycarboxylate, conventional glass ionomer cements, and resin-modified glass ionomer cements (all classified as acid-base cements) have all been recommended for use in all-ceramic crown restorations.[22-25] In comparison to non-adhesive cementation, it has been claimed that cementation utilizing adhesive luting resins enhances the mechanical qualities of definitive restorations.[26]Previous research demonstrates that when sticky resin cement was used to affix all ceramic crowns, The mean maximal masticatory forces were less than the mean fracture loads. [26,27,28]. In contrast to non-adhesive cementation.