Abstract
The purpose of the investigation was to analyze fracture resistance and mode of failure of zirconium oxide (zirconia) abutments placed on dental implants bearing crowns of different esthetic materials: zirconia, lithium disilicate (LDS), and nano-ceramic resin, for replacing single teeth in the anterior sector. Eighty implant-abutment-crown units were divided into four groups: Group T-MC (control): 20 metal-ceramic crowns cemented onto titanium abutments; Group Z-Z: 20 zirconia crowns on zirconia abutments; Group Z-LD: 20 lithium disilicate crowns on zirconia abutments; and Group Z-NCR: 20 nano-ceramic resin crowns on zirconia abutments. Specimens underwent a fatiguing process (dynamic loading and thermocycling), followed by static loading to evaluate mechanical fracture resistance, and the mode of failure produced. Mean fracture resistance values were: Control Group T-MC, 575.85±120.01 N; Group Z-Z 459.64±66.52 N; Group Z-LD, 531.77±34.10 N; and Group Z-NCR, 587.05±59.27 N. In Group T-MC, fracture occurred in the prosthetic fixing screw in 100% of specimens. In Group Z-Z, 80% of fractures occurred in the fixing screw, 15% in the abutment, and 5% in the abutment and crown. In Group Z-LD, 60% of fractures were produced in the fixing screw and 40% in the abutment. In Group Z-NCR, 70% of fractures were produced in the fixing screw and 30% in the abutment. All the abutments and crowns analyzed have the potential to withstand the physiological occlusal forces to which they would be subject in the anterior region. Lithium disilicate and nano-ceramic resin crowns cemented onto zirconia abutments are a good restoration alternative for single implants in the anterior sector.
Highlights
A single missing tooth in the anterior sector is a complex challenge to the dentist, due to the need for restorations that are both esthetic and functional
Aluminum oxide has been found to present lower mechanical resistance to the occlusal forces exerted in the anterior sector in both in vitro and in vivo trials, and for this reason, in recent years, zirconium oxide has been proposed as a material for fabricating this type of abutment [10]
The Bonferroni test confirmed that Group Z-Z obtained significantly lower fracture resistance values in comparison with the other three groups: Z-Z vs. T-CM (p-value
Summary
A single missing tooth in the anterior sector is a complex challenge to the dentist, due to the need for restorations that are both esthetic and functional. Aluminum oxide has been found to present lower mechanical resistance to the occlusal forces exerted in the anterior sector in both in vitro and in vivo trials, and for this reason, in recent years, zirconium oxide has been proposed as a material for fabricating this type of abutment [10]. New laboratory studies have been published evaluating fracture resistance of anterior restorations with zirconia abutments, obtaining values above the occlusal forces exerted in the anterior sector (300 N) [1,6,12]. The aim of this in vitro study was to analyze the fracture resistance and mode of failure produced (after fatiguing) of zirconia abutments bearing crowns fabricated from different esthetic materials: zirconia, lithium disilicate (LDS), and nano-ceramic resin, compared with the classic materials titanium abutments bearing metal-ceramic crowns used to replace a single missing anterior tooth
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