Mechanical testing of thin-walled zirconia abutments

Abstract

Although the use of zirconia abutments for implant-supported restorations has gained momentum with the increasing demand for esthetics, little informed design rationale has been developed to characterize their fatigue behavior under different clinical scenarios. However, to prevent the zirconia from fracturing, the use of a titanium connection in bicomponent aesthetic abutments has been suggested.Objective:Mechanical testing of customized thin-walled titanium-zirconia abutments at the connection with the implant was performed in order to characterize the fatigue behavior and the failure modes for straight and angled abutments.Material and Methods:Twenty custom-made bi-component abutments were tested according to ISO 14801:2007 either at a straight or a 25º angle inclination (n=10 each group). Fatigue was conducted at 15 Hz for 5 million cycles in dry conditions at 20ºC±5ºC. Mean values and standard deviations were calculated for each group. All comparisons were performed by t-tests assuming unequal variances. The level of statistical significance was set at p≤0.05. Failed samples were inspected in a polarized-light and then in a scanning electron microscope.Results:Straight and angled abutments mean maximum load was 296.7 N and 1,145 N, the dynamic loading mean Fmax was 237.4 N and 240.7 N, respectively. No significant differences resulted between the straight and angled bi-component abutments in both static (p=0.253) and dynamic testing (p=0.135). A significant difference in the bending moment required for fracture was detected between the groups (p=0.01). Fractures in the angled group occurred mainly at the point of load application, whereas in the straight abutments, fractures were located coronally and close to the thinly designed areas at the cervical region.Conclusion:Angled or straight thin-walled zirconia abutments presented similar Fmax under fatigue testing despite the different bending moments required for fracture. The main implication is that although zirconia angled or straight abutments presented similar mechanical behavior, the failure mode tended to be more catastrophic in straight (fracture at the cervical region) compared to angled abutments.

Effects of Liner-Bonding of Implant-Supported Glass–Ceramic Crown to Zirconia Abutment on Bond Strength and Fracture Resistance

“…The two-piece system of zirconia abutments involves using a titanium base to establish an interfacial connection with similar materials to the implant to avoid possible complications resulting from the use of dissimilar materials [18,22]. These abutments were found to demonstrate a higher bond strength when the abutment was roughened with 110 µm alumina particles at 2.5 atm, coated with a ceramic primer, and bonded with a dual-cure self-adhesive resin cement [45].…”

“…However, problems may occur when bonding a final prosthesis to a zirconia ceramic abutment [18,21,22]. The resin cement may not adhere to the zirconia ceramic abutment because of the lack of undercut features commonly created by blasting with air-borne particle abrasion technology and/or etching with hydrofluoric acid.…”

Fracture resistance and the mode of failure produced in metal-free crowns cemented onto zirconia abutments in dental implants

“…To reproduce the conditions that restorations are subject to in the oral medium (mechanical masticatory stress, temperature changes) specimens underwent an artificial ageing process consisting of dynamic loading and thermocycling. The literature includes various in vitro studies [6,15–17] that have followed this type of procedure for evaluating the fracture resistance of ceramic materials such as zirconia, as they can suffer decreases in strength due to low temperature degradation (LTD). This involves a transition in the zirconia phase (from tetragonal to monoclinic phase) resulting from repeated thermal stress to the restorations [18].…”

Optimized Planning and Evaluation of Dental Implant Fatigue Testing: A Specific Software Application

“…In short, while the current ISO 14,801 standard offers improvements in the dynamic loading testing for dental implants, it nonetheless continues to suffer serious limitations in its effective application in the fatigue limit determination. The fact that most of the dental studies in this field do not satisfy the high number of specimens demanded by the normative only serves to confirm these inherent flaws [20,[33][34][35][36][37][38].…”