The Fracture Resistance of Additively Manufactured Monolithic Zirconia vs. Bi-Layered Alumina Toughened Zirconia Crowns When Cemented to Zirconia Abutments. Evaluating the Potential of 3D Printing of Ceramic Crowns: An In Vitro Study (original) (raw)
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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.
Clinical Oral Investigations, 2023
Objectives The aim of this study was to evaluate the effect of cyclic mechanical loading on the fracture resistance of 3D-printed zirconia crowns in comparison to milled zirconia crowns. Materials and methods Monolithic zirconia crowns (n = 30) were manufactured using subtractive milling (group M) and 3D additive printing (group P). Nine samples of each group were fractured under one-time loading while the other 6 samples were subjected to cyclic loading for 1.2 million cycles before being subjected to one-time loading until fracture. Scanning electron microscope (SEM) fractographic analysis was carried out on fractured fragments of representative samples. Results The mean for fracture resistance of group M was 1890 N without cyclic loading and 1642 N after being subjected to cyclic loading, and they were significantly higher than that of group P (1658 N and 1224 N respectively). Conclusions The fabrication technique and cyclic loading affect the fracture resistance of zirconia crowns. Although the fracture resistance values for the 3D-printed crowns were lower than those of the milled, still they are higher than the masticatory forces and thus could be considered being clinically acceptable. Clinical relevance Concerning fracture resistance, 3D-printed crowns can withstand the masticatory forces for the long term without any cracks or failure.
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;
Egyptian Dental Journal
Statement of the problem: Despite their outstanding esthetic characteristics, the adequacy of implant-supported all-ceramic crowns under occlusal loads in the posterior segment of the jaw remains questionable. Aim of the study: Evaluation of the fracture resistance of different CAD/CAM fabricated implant-supported all-ceramic monolithic posterior crowns cemented on ready and custom made zirconia abutments. Materials and methods: 30 internal connection titanium dummy implants were embedded in epoxy resin and randomly divided into three groups (n=10 each) according to the crown material used; Group I: Polycrystalline ceramic (Katana Zirconia), Group II: Hybrid ceramic (Vita Enamic) and Group III: Lithium disilicate glass ceramic (IPS e.max CAD).All crowns were CAD/CAM fabricated as monolithic maxillary right first premolar.In each group, five crowns were cemented on ready made zirconia abutments (subgroup A) while the other five were cemented on custom made zirconia abutments (subgroup B). All samples were thermocycled (5 o to 55 o ,10 seconds dwell time) then compressively loaded under axial static load till fracture using a universal testing machine with a loadcell of 5 kN at a cross-head speed of 1mm/min. The load required to fracture was recorded in Newton and failure modes were visually analyzed. Statistical analyses were performed by Two-way ANOVA and Tukey's post-hoc test.(P ≤ 0.05) Results: Fracture resistance of implant-supported all-ceramic monolithic posterior crowns was statistically significantly affected by the ceramic crown material and abutment type (P<0.001). Either with ready or custom-made zirconia abutments; zirconia crowns recorded the statistically significantly highest fracture resistance mean value followed by IPS e.max CAD ones while Vita Enamic crowns recorded the lowest values with no statistically significant difference between them and IPS e.max CAD crowns. Zirconia and Vita Enamic crowns cemented on custom made abutments recorded statistically significantly higher mean fracture resistance values than those cemented on ready made one. However, IPS e.max Cad crowns cemented on both abutment types showed statistically insignificant difference. Different failure modes were observed among the tested ceramic crowns without fracture of any abutment.
The journal of advanced prosthodontics, 2018
The aim of this study was to investigate the fracture resistance under chewing simulation of implant-supported posterior restorations (crowns cemented to hybrid-abutments) made of different all-ceramic materials. Monolithic zirconia (MZr) and monolithic lithium disilicate (MLD) crowns for mandibular first molar were fabricated using computer-aided design/computer-aided manufacturing technology and then cemented to zirconia hybrid-abutments (Ti-based). Each group was divided into two subgroups (n=10): (A) control group, crowns were subjected to single load to fracture; (B) test group, crowns underwent chewing simulation using multiple loads for 1.2 million cycles at 1.2 Hz with simultaneous thermocycling between 5℃ and 55℃. Data was statistically analyzed with one-way ANOVA and a Post-Hoc test. All tested crowns survived chewing simulation resulting in 100% survival rate. However, wear facets were observed on all the crowns at the occlusal contact point. Fracture load of monolithic l...
Australian Dental Journal, 2011
Background: An in vitro study was performed to assess the effect of three implant abutment angulations and three core thicknesses on the fracture resistance of overlaying computer-aided manufacturing (CAM) milled zirconia (Cercon Ò system) single crowns. Methods: Three groups, coded A to C, with different implant abutment angulations (group A ⁄ 0°, group B ⁄ 15°and group C ⁄ 30°angulation) were used to construct 15 crowns for each angulation. Forty-five overlay restorations were milled using the Cercon Ò system with zirconium core thicknesses of 0.4, 0.6 and 0.8 mm using five crowns for each angulation. The final restorations were prepared and stored in distilled water at mouth temperature (37°C) for 24 hours prior to testing. The restorations were cemented using Temp Bond Ò . The load required to break each crown and the mode of failure were recorded. All the results obtained were statistically analysed by the ANOVA test (level of significance p < 0.05). Tested crowns were examined using a stereomicroscope at 40X and selected crowns (five randomly selected from each group were further examined by scanning electron microscopy) to reveal the zirconia-ceramic interface and to determine the fracture origin. Results: Implant abutment angulations significantly (p < 0.05) reduced the fracture resistance of overlaying CAM-milled zirconia single crowns. The fracture loads of Cercon Ò crowns cemented onto abutment preparations with a 30°angulation were the lowest of the groups tested. The core thickness (0.4 to 0.8 mm) did not significantly (p > 0.05) affect the fracture resistance of the CAM-milled zirconia single crowns. SEM showed that the origin of the fracture appeared to be located at the occlusal surfaces of the crowns and the crack propagation tended to radiate from the occlusal surface towards the gingival margin. Conclusions: The implant angulation of 30°significantly (p < 0.05) reduced the fracture resistance of overlaying CAMmilled zirconia single crowns. Reducing the core thickness from 0.8 mm to 0.4 mm did not affect (p > 0.05) the fracture resistance of overlaying CAM-milled zirconia single crowns.
SciDoc Publishers, 2021
This study aims to evaluate fracture resistance of monolithic zirconia crowns designed using CAD/CAM technique and veneered zirconia crowns. Twenty metal orthodontic abutments were designed and fabricated using a metal laser printer. Specimens were then divided into two groups (n=10). All specimens were bonded and attached using glass ionomer cement. Samples were tested for fracture resistance using a general material testing machine (Testometric). Data were statistically analyzed using Student’s t-test. Significant statistic differences were found between the study groups as monolithic zirconia crowns displayed higher fracture resistance in comparison with veneered zirconia crowns, since monolithic zirconia crowns happened to solve the issue of chipping faced with veneers.
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
Medicine and Pharmacy Reports
Introduction. The use of zirconia based all-ceramic restorations are preferred nowadays owing to superior biologic and esthetic properties. However, these restorations have also reported higher incidences of fracture and chipping. The clinical success may be enhanced by optimizing the core design, through the introduction of monolithic zirconia, or the layered crowns can be strengthened by adding the cervical collar to them. Objective. This study was performed with the objective to compare and evaluate the fracture load of monolithic and bilayered zirconia crowns with and without a cervical collar. Methods. A prospective observational study was carried out to compare 45 fabricated zirconia crowns of three different designs on a customized metal mould. The samples were oriented on the metal mould and subjected to confocal microscope for the evaluation of marginal integrity followed by cementing the crown on the metal mould and subjecting it to the universal testing machine for the an...
Fracture Strength of Aged Monolithic and Bilayer Zirconia-Based Crowns
BioMed Research International, 2015
The purpose of this study was to evaluate the effect of design and surface finishing on fracture strength of yttria-tetragonal zirconia polycrystal (Y-TZP) crowns in monolithic (1.5 mm thickness) and bilayer (0.8 mm zirconia coping and 0.7 mm porcelain veneer) configuration after artificial aging. Bovine incisors received crown preparation and Y-TZP crowns were manufactured using CAD/CAM technique, according to the following groups (n=10): Polished monolithic zirconia crowns (PM); Glazed monolithic zirconia crowns (GM); Bi-layer crowns (BL). Crowns were cemented with resin cement, submitted to artificial aging in a chewing simulator (2.5 million cycles/80 N/artificial saliva/37°C), and tested for fracture strength. Two remaining crowns referring to PM and GM groups were submitted to a chemical composition analysis to measure the level of yttrium after aging. One-way ANOVA and Tukey’s test (P=.05) indicated that monolithic zirconia crowns presented similar fracture strength (PM=3476....