Biomechanical properties of polymer-infiltrated ceramic crowns on one-piece zirconia implants after long-term chewing simulation

Abstract

BackgroundImplant and superstructure provide a complex system, which has to withstand oral conditions. Concerning the brittleness of many ceramics, fractures are a greatly feared issue. Therefore, polymer-infiltrated ceramic networks (PICNs) were developed. Because of its high elastic modulus, the PICN crown on a one-piece zirconia implant might absorb forces to prevent the system from fracturing in order to sustain oral forces. Recommendations for the material of superstructure on zirconia implants are lacking, and only one study investigates PICN crowns on these types of implants.Accordingly, this study aimed to examine PICN crowns on one-piece zirconia implants regarding bond strength and surface wear after long-term chewing simulation (CS).MethodsTwenty-five hybrid ceramic crowns (Vita Enamic, Vita Zahnfabrik) were produced using computer-aided design/computer-aided manufacturing (CAD/CAM) technology and adhesively bonded (RelyX™ Ultimate, 3M ESPE) to zirconia implants. Twenty of the specimens underwent simultaneous mechanical loading and thermocycling simulating a 5-year clinical situation (SD Mechatronik GmbH). Wear depth and wear volume, based on X-ray micro-computed tomography volume scans (Skyscan 1172-100-50, Bruker) before and after CS, were evaluated.All crowns were removed from the implants using a universal testing machine (Z010, Zwick GmbH&Co.KG). Subsequently, luting agent was light microscopically localized (Stemi 2000-C, Zeiss).With a scanning electron microscope (SEM, Phenom™ G2 pro, Phenom World), the area of abrasion was assessed.Results After CS, none of the tested crowns were fractured or loosened.The maximum vertical wear after CS was M = 0.31 ± 0.04 mm (mean ± standard deviation), and the surface wear was M = 0.74 ± 0.23 mm3.The pull-off tests revealed a 1.8 times higher bond strength of the control group compared to the experimental group (t(23) = 8.69, p < 0.001).Luting agent was mostly located in the crowns, not on the implants.The area of abrasion showed avulsion and a rough surface. ConclusionsPICN on one-piece zirconia implants showed high bond strength and high wear after CS.

Chewing simulation of zirconia implant supported restorations

“…Glazed zirconia surfaces resulted in a significantly higher abrasion of the enamel antagonist than machined zirconia, which was also significantly higher than polished surfaces [44]. For VE, abrasion after chewing simulation has been previously analyzed using a microCT with similar results as in the present study [28]. Abrasion of VE is similar as for human enamel [43].…”

“…The chewing simulation of 1.2 Mio cycles that was applied with a force of 49N is reported to simulate aging in the mouth of 5 years [18,42]. In most studies where a chewing simulation is applied, steatite is used as an antagonist [20,24,[26][27][28]42].…”

“…The other 16 specimens of each material were subjected to aging followed by either the fracture load test of the 8 polished specimens or retention test of the 8 unpolished specimens as described above. For the aging simulation, the crowns were first placed in a chewing simulator (CS-4.8, SD Mechatronik, Feldkirchen, Germany) and subjected to 1.2 Mio cycles [20,23,24,26,27] with a frequency of 1.5Hz (maximal capacity of the chewing simulator) and a force of 49N to initiate subcritical crack growth [20,[26][27][28]. Steel balls with a diameter of 4.5mm served as antagonists.…”

Failure Load and Fatigue Behavior of Monolithic Translucent Zirconia, PICN and Rapid-Layer Posterior Single Crowns on Zirconia Implants

“…CAD/CAM RMCs and especially polymer-infiltrated ceramic networks (PICN) were introduced as more flexible and elastic materials, combining positive material properties of ceramics and polymers [ 21 , 22 ]. Due to its dual network and a dentin-like modulus of elasticity, PICN could potentially absorb and distribute occurring occlusal forces more favorably, making it an interesting restorative material for implant prosthodontics [ 23 , 24 ].…”

Shade Stability of Polymer-Infiltrated and Resin Nano Ceramics

“…These new materials combine positive characteristics like fracture and flexural strength [ 1 , 2 ]. Altogether this leads to a high elasticity, which provides a decisive advantage on one-piece zirconia implants as a fixed connection and for implementation of the dynamic chewing processes [ 3 , 4 ]. VE features an intertwined network of polymer and ceramic parts as its structure (polymer-infiltrated ceramic) and combines the mechanical properties of both ceramic and resin-based composites [ 5 ].…”