Investigation of Fracture Resistance of Zirconia Restorations After Different Surface Treatments (original) (raw)
Related papers
J Prosthodont, 2019
Purpose: To compare the fracture resistance of implant-supported milled zirconia, milled lithium disilicate, and additively manufactured zirconia crowns. Materials and Methods: Maxillary cast with a dental implant replacing right second bicuspid was obtained. Custom abutments and full-contour crowns for milled zirconia, milled lithium disilicate, and additively manufactured zirconia crowns (n = 10/group) were digitally designed and fabricated. The crowns were cemented to implant-supported zirconia abutments and mounted onto polyurethane blocks. Fracture resistance was determined by vertical force application using a universal testing machine at a crosshead speed of 2 mm/minute. Kruskal-Wallis test was used to analyze data and failure mode was determined for all the groups. Results: Milled zirconia crowns demonstrated the highest median fracture resistance (1292 ± 189 N), followed by milled lithium disilicate (1289 ± 142 N) and additively manufactured zirconia (1243.5 ± 265.5 N) crowns. Statistical analysis showed no significant differences in fracture resistance between the groups (p = 0.4). All specimens fractured at the implant-abutment interface. Conclusion: Additively manufactured zirconia crowns demonstrated similar fracture resistance to milled ceramic crowns, when cemented to implant supported zirconia abutments. The results of this in vitro study signify the promising potential of additive manufacturing for the fabrication of all ceramic zirconia crowns.
A comparison of fracture strength among different brands of translucent zirconia crown restorations
2016
Objectives: As the development of translucent zirconia crown using CAD/CAM technology, the usage of full zirconia crown is gradually increased. The purpose of this study was to investigate the highest fracture strength of translucent zirconia full zirconia crowns among different brands of translucent zirconia. Methods: Maxillary 1 st premolar resin teeth were prepared the total circumferential axial reduction was about (1 mm), and axial taper of 6°. Three brands of translucent zirconia (Whitepeaks, Imes-icor and Dentaldirect) that was used in three groups, every group contain five full zirconia crowns using CAD/CAM system (CAD/CAM system 250i, Imesicor, Germany). The samples seated on the resin die using. All specimens were tested with a universal testing machine. Single load-to-fracture was applied on the lingual aspect of the facial cusp at a rate of 1mm/min. The specimens were thoroughly evaluated for bulk fracture with fractography. Results: Statistically high significant difference (p < 0.00) was found between the groups. The fracture strength of the groups varied Whitepeaks crowns was (2737.5 ± 106) N, which was significantly higher than the two overall mean fracture strength measured for the Imes-icor crowns (3620 ± 40) N and Dental direct crowns (3830 ± 130) N, the Dental direct highest fracture strength than other groups. Conclusions. The fracture strength of Dental direct crowns is considerably higher than that of Whitepeaks crown, The fracture strength of all the groups made of monolithic high translucent Y-TZP is exceeded human maximum bite force, sufficient for clinical use for the majority of patients. 1.introdaction: All-ceramic dental restorations have been widely applied in prosthodontics because of their aesthetic, biocompatible, absence of metal and inert properties. 1 Among the major short comings of brittle ceramics is susceptive to flaws and defects. In recent decades, dental ceramics with high strength and toughness have been developed to meet the requirements of routine functions similar to the functions of teeth. Despite their general success, some allceramic crowns experience failure after years of service. As indicated in a clinical survey, the main cause of failure is fracture of the ceramics. Because the estimated survival rates of all-ceramic crowns were 97.3% at 5 years, 93.5% at 10 years and 78.5% at 20 years, their long-term success remains a major concern for restorative dentistry. [2] Zirconium oxide-based materials, especially yttria-tetragonal zirconia polycrystals (Y-TZP), were recently introduced forprosthetic rehabilitations as a core material for single crowns, conventional and resin-bonded fixed partial dentures (FPDs) [3] The combination of Y-TZP and computer-aided design/computer-aided manufacture (CAD/CAM) systems is a new approach that reduces the number of steps in prosthetic manufacturing and eliminates the variables introduced by the manual procedures of the dental technician. Y-TZP exhibits exceptional physical and mechanical properties, such as high flexural strength, fracture toughness, hardness, wear and corrosion resistance in acidic and basic ambient conditions, translucency [3] , colour stability, greater effectiveness of diagnostic radiographs [4] [5] , and high biocompatibility. Moreover, the polycrystalline structure, which lacks a glass matrix, makes zirconia ceramic more resistant to hydrofluoridric acid etching and, as a consequence, resistant to chemical roughening [6]. Mechanical properties of zirconia have been reported to be higher than other ceramics for dental applications. Fracture resistance of 6-10 MPa/m1/2, a flexural strength of 900-1200 MPa and a compression brought to you by CORE View metadata, citation and similar papers at core.ac.uk
The International journal of oral & maxillofacial implants
Zirconia implant abutments offer enhanced esthetics and promote biologic sealing; however, the effect of laboratory or intraoral preparation on the mechanical stability of zirconia has not been investigated. The purpose of the study was to evaluate the influence of the preparation mode and depth on the fracture strength of zirconia abutments restored with lithium disilicate crowns. To replace a maxillary central incisor (11.0 mm in height and 8.0 mm in width), 35 lithium disilicate crowns were cemented onto zirconia abutments on 4.5- ° - 15-mm titanium implants. Lithium disilicate implant crowns were divided into five study groups (n = 7) according to the abutment preparation mode (milling by the manufacturer or milling by the Celay System [Mikrona] [P]) and preparation depth (0.5 mm [A], 0.7 mm [B], or 0.9 mm [C]). All groups were subjected to quasi-static loading (S) at 135 degrees to the implant axis in a universal testing machine. Mean fracture strengths were: group SA, 384 ± 84...
PLOS ONE
Structural durability of screw-cement-retained implant-supported zirconia-based restorations is an important factor in choosing the best type of restoration for clinical use. This study aimed to evaluate the effects of thermocycling on the fracture resistance of different types of screw-cement-retained implant-supported zirconia-based restoration. Two experimental groups (monolithic zirconia and porcelain-veneered zirconia) and a control group of porcelain-fused-to-metal restorations were fabricated via CAD-CAM (n = 14 per group). Half of the specimens of each group (n = 7) were subjected to 10000 thermal cycles. The compressive force was applied and the force leading to fracture was measured by using a Universal Testing Machine. The fractured modes were classified under a scanning electron microscope. The data were analyzed through two-way ANOVA, one-way ANOVA, and independent samples t-test (α = 0.05). Among the non-thermocycled subgroups, the monolithic zirconia specimens were si...
In recent years, Zirconia-reinforced Lithium Silicate ceramic (ZLS), combining lithium-silicate and zirconia features, has shown to have excellent mechanical and aesthetic characteristics. Thus, the aim of this study was to compare the fracture strength of ZLS single crowns cemented with two different cementation techniques. Twenty crowns were realised and cemented on teeth replicas achieved from an extracted premolar human tooth. The samples were divided into two groups of 10 specimens each, Glass-ionomeric cement (GIC) group and Self-Adhesive Resin Cement (ARC) group. The mechanical test was performed using a universal testing machine. The specimens were then evaluated with a scanning electron microscope (SEM) to identify for all crowns and related abutments the pattern of fracture after the breaking point. The data obtained were statistically analysed. The mean fracture toughness values and standard deviations (±SD) were 2227 ± 382 N and 3712 ± 319 N respectively for GIC and ARC groups. In fact, t-test showed a statistically significant difference between the two groups (p < 0.001). Moreover, the SEM results demonstrated portions of abutments still attached to the crown fragments in the ARC group, whilst these were not present in the GIC group. Within the limitations of this study, these results suggest the use of adhesive cementation for ZLS crowns, which significantly increase the compressive strength of ZLS restorations compared to GIC.
To evaluate the fracture resistance of all-ceramic crowns cemented on titanium and zirconia implant abutments. Material and Methods: Customized implant abutments for maxillary right central incisors made of titanium (Ti) and zirconia (Zr) (n = 60, n = 30 per group) were fabricated for an internal connection implant system. All-ceramic crowns were fabricated for their corresponding implant abutments using the following systems (n = 10 per group): (1) monolithic computer-aided design/computer-assisted manufacture (CAD/ CAM) lithium disilicate (MLD); (2) pressed lithium disilicate (PLD); (3) yttrium stabilized tetragonal zirconia polycrystal (YTZP). The frameworks of both PLD and YTZP systems were manually veneered with a fluorapatitebased ceramic. The crowns were adhesively cemented to their implant abutments and loaded to fracture in a universal testing machine (0.5 mm/minute). Data were analyzed using two-way analysis of variance (ANOVA) and Tukey's test (α = 0.05). Results: Both the abutment material (P = .0001) and the ceramic crown system (P = .028) significantly affected the results. Interaction terms were not significant (P = .598). showed the highest mean fracture resistance among all abutment −crown combinations (340.3 ± 62 − 495.9 presented significantly higher values than with Zr abutments (392.9 ± 55 − 340.3 ± 62 N) (P < .05). MLD crown system showed significantly higher mean fracture resistance compared to manually veneered ones on both Ti and Zr abutments (P < .05). While Ti-MLD and Ti-PLD abutment-crown combinations failed only in the crowns without abutment fractures, Zr-YTZP combination failed exclusively in the abutment without crown fracture. Zr-MLD and Zr-PLD failed predominantly in both the abutment and the crown. Ti-YTZP showed only implant neck distortion. Conclusions: The highest fracture resistance was obtained with titanium abutments restored with MLD crowns, but the failure type was more favorable with
Fracture strength of zirconia and alumina ceramic crowns supported by implants
Journal of Oral Implantology, 2014
Due to the brittleness and limited tensile strength of the veneering glass-ceramic materials, the methods that combine strong core material (as zirconia or alumina) is still under debate. The present study aims to evaluate the fracture strength and the mechanism of failure through fractographic analysis of single all-ceramic crowns supported by implants. Forty premolar cores were fabricated with CAD/CAM technology using alumina (n = 20) and zirconia (n = 20). The 1 specimens were veneered with glass-ceramic, cemented on titanium abutments, and subjected to loading test until fracture. SEM fractographic analysis was also performed. The fracture load was 1165 (±509) N for alumina and 1638 (±662) N for zirconia with a statistically significant difference between the two groups (p = 0.026). Fractographic analysis of alumina-glass-ceramic crowns, showed the presence of catastrophic cracks of the entire thickness of the alumina core;
Zirconia a Modern Ceramic Material in Dentistry - a Systematic Review
Among the dental ceramics, zirconia has emerged as a resourceful and promising material because of its biological, mechanical and optical properties, which has certainly accelerated its routine use in CAD/CAM technology for different types of prosthetic treatment. The zirconia systems currently available for use in dentistry include ceramics with a 90% or higher content zirconium dioxide, which is the yttrium, stabilized tetragonal Zirconia (Y-TZP) and glass infiltrated ceramics with 35% partially stabilized zirconia. Zirconia based restorations are quite versatile and can be used for crowns, bridges, implant abutments and fixtures and as post materials. This article reviews the unique property of zirconia and its wide application in dentistry, with more emphasis on prosthetic uses. Keywords: Zirconia, Esthetics, Restorations, Mechanical properties.
2014
Fractures during clinical function have been reported as the major concern associated with all-ceramic dental restorations. The aim of this study was to analyze the fracture features of glass-ceramic and zirconia-based restorations fractured during clinical use. Twenty-seven crowns and onlays were supplied by dentists and dental technicians with information about type of cement and time in function, if available. Fourteen lithium disilicate glass-ceramic restorations and 13 zirconia-based restorations were retrieved and analyzed. Fractographic features were examined using optical microscopy to determine crack initiation and crack propagation of the restorations. The material comprised fractured restorations from one canine, 10 incisors, four premolars, and 11 molars. One crown was not categorized because of difficulty in orientation of the fragments. The results revealed that all core and veneer fractures initiated in the cervical margin and usually from the approximal area close to the most coronally placed curvature of the margin. Three cases of occlusal chipping were found. The margin of dental all-ceramic single-tooth restorations was the area of fracture origin. The fracture features were similar for zirconia, glass-ceramic, and alumina single-tooth restorations. Design features seem to be of great importance for fracture initiation.