Influence of artificial aging on mechanical properties of commercially and non-commercially available zirconia dental implants

Abstract

To evaluate the effect of artificial aging on the mechanical resistance and micromechanical properties of commercially and noncommercially available zirconia dental implants. Methods: Scanning electron microscopy (SEM) and X-ray computed tomography (X-CT) were performed on implant systems including: Z-systems®, Straumann®, Zibone® and commercially and non-commercially available TAV dental® with varying grain sizes. Accelerated aging was performed at 134 °C and 2-bar pressure for 30 hours. Before and after aging, the mechanical load to failure was investigated and the bending moments were calculated. Nanoindentation responses of the representative Zibone implant before and after aging were per-formed to evaluate the effects of aging on hardness (H) and Young's modulus (E). A two-sample t-test statistical analysis was used to determine significant differences of bending moments within groups. Results: All implants presented with compact and homogenous core structures without porosities. The bending moment was significantly increased after aging for all groups (P ≤ 0.05) except for Z-systems (significant de-crease (P = 0.022)) and TAV group 3 (no significant increase (P = 0.181)). The increase in bending moment was less pronounced with increasing grain size in TAV groups (group 1: P = 0.036, group 2: P = 0.05, group 3: P = 0.18). E and H were reduced approximately 32% and 18% respectively following aging within the trans-formed, microcracked zone of the presentative Zibone implant. Conclusions: Aging led to both increase and decrease of the mechanical properties of the implant systems ana-lyzed. The apparent contrast amongst groups can be explained based on differences in grain sizes and surface features. Aging decreased micromechanical properties of one implant system which warrants further in-vestigation.

Fracture Resistance of Zirconia Oral Implants In Vitro: A Systematic Review and Meta-Analysis

“…Manufacturing was mostly subtractive (n = 591 implants), but ceramic injection-molding (CIM) was likewise used for the production (n = 120 implants) [15,19,21,25]. There was no statistically significant difference in the fracture resistance of implants when manufacturing method (subtractive: 397.5 ± 177.4 Ncm, CIM: 364.8 ± 116.7 Ncm) was regarded (p > 0.095).…”

“…When only the fracture load [N] during static loading was reported, three options allowed for the calculation of the bending moment: (1) embedding was described to fully respect ISO 14801 (prescribing a lever arm of 5.5 mm allowing for the calculation of the bending moment), (2) all details regarding the embedding were provided in the manuscript (e.g., by providing a scheme) or (3) the bending moment and/or lever arm were provided by the authors upon request. As an example, six of the included studies adopted ISO 14801 for embedding [15,17,21,[24][25][26], whereas three provided all necessary information [19,27,28] allowing us to calculate the bending moment (embedding level, angulation, total sample length, point of loading). In the remaining cases the bending moment was reported [13,20,22] or sent by the authors [12,18,29,30].…”

“…All 17 articles published between 2009 [29] and 2019 [15,16] were included and analyzed in the present meta-analysis. Moreover, unpublished data of two projects currently under review and in preparation of the manuscript were included (Table 1).…”

“…This did not change when stratifying the outcome for 1-(p = 0.273) and 2-piece (p = 0.191) implants. However, the included studies evaluated only very few implants in the range of 3 mm (range: 3.0-3.3 mm; n = 15, 207.2 ± 14.3 Ncm) [24,27] and 5 mm (range: 4.5-5.0 mm; n = 41, 349.4 ± 125.4 Ncm) [15,19,27,28], whereas the majority of implants had a diameter in the range of 4 mm (range: 3.8-4.4 mm; n = 675, 394.9 ± 170.4 Ncm). Boxplots can be seen in Figure 5.…”

“…To overcome this, different treatments were proposed to mimic intraoral conditions to the extent possible for the evaluation of ceramic implants. These treatments included thermal aging (high-temperature conditions or thermal cycling) [15,16] and/or dynamic loading procedures (various exposure times and different applied loading modes) [12,17]. Zirconia implants evaluated regarding their fracture resistance in the literature comprised a heterogeneous range of features like material selection (yttria-stabilized tetragonal zirconia polycrystal, Y-TZP or alumina-toughened zirconia, ATZ) [18], design (1-or 2-piece) [13], manufacturing (subtractive or by ceramic injection molding, CIM) [19], restoration (anatomical crown, hemisphere or no restoration) [20,21], abutment preparation (in the case of 1-piece implants) [22], or assembly (in the case of 2-piece implants) [13].…”