Abstract
Purpose: To analyze in vitro the mechanical behavior of five types of complete coverage crowns fabricated from different materials. Materials and methods: Seventy-five full coverage crowns were divided into five groups according to material: Group I, metal core with feldspathic ceramic covering (MC- control group); Group II, zirconia core with feldspathic ceramic covering (CZ); Group III, tetragonal monolithic zirconia (TMZ); Group IV, cubic monolithic zirconia (CMZ); Group V, high molecular weight polymethyl methacrylate (PMMAG) doped with graphene nanoparticles. All crowns underwent in vitro fatiguing by dynamic loading in wet conditions to simulate the masticatory forces to which prosthodontic materials are subject in the oral medium. Lastly, fracture resistance was evaluated by static compression testing. Results: The fracture resistance values obtained were as follows: Group MC, 2443.6 ± 238.6 N; Group CZ, 2095.4 ± 329.2 N; Group TMZ, 2494.6 ± 236.6 N; Group CMZ, 1523.6 ± 325.2 N; and Group PMMAG, 1708.9 ± 386.6 N. Group MC presented higher strength with statistically significant differences in comparison with Groups CZ (P = 0.002), CMZ (P < 0.001), and PMMAG (P < 0.001). Weibull distribution showed less probability of cumulative biomechanical failure in Groups MC and TMZ. Conclusions: Metal-ceramic and tetragonal zirconia showed high fracture resistance, while cubic zirconia and PMMA doped with graphene nanoparticles obtained lower values.
Highlights
The rehabilitation of lost dental tissue is one of the main objectives of prosthetic dentistry.Full coverage crowns are the classic therapeutic option for restoring teeth that have suffered major destruction
3M ESPE); Group PMMAG (n = 15) polymethyl methacrylate (PMMA) doped with graphene nanoparticles
Be significantly more resistant(Group to fracture than zirconia core crowns (Group were found to be significantly more resistant to fracture than zirconia core crowns (Group CZ) (P < 0.001; Tanhane test) and graphene-doped PMMA (Group PMMAG)
Summary
The rehabilitation of lost dental tissue is one of the main objectives of prosthetic dentistry. The point clouds obtained in scanning are transformed through a CAD software into a smooth and continuous surface, which in some cases can cause reproducibility errors of the anatomy of the preparation that will influence the marginal and internal fit of the prosthetic restoration [16] The aim of this trial was to analyze the in vitro fracture resistance of metal-free zirconia and polymer-based crowns (TMZ, CMZ, PMMAG) compared with conventional crowns (metal/zirconia core with ceramic covering, MC-CZ)
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