scholarly journals Fracture Resistance of Monolithic Zirconia Crowns in Implant Prostheses in Patients with Bruxism

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1623 ◽  
Author(s):  
Ting-Hsun Lan ◽  
Chin-Yun Pan ◽  
Pao-Hsin Liu ◽  
Mitch M. C. Chou
Keyword(s):  
Cyclic Loading ◽  
Computer Aided Design ◽  
Fracture Resistance ◽  
Testing Machine ◽  
Von Mises Stress ◽  
High Fracture ◽  
Computer Aided ◽  
Zirconia Crowns ◽  
Monolithic Zirconia ◽  
Von Mises

The aim of this study is to determine the minimum required thickness of a monolithic zirconia crown in the mandibular posterior area for patients with bruxism. Forty-nine full zirconia crowns, with seven different occlusal thicknesses of 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0 mm, were made by using a computer-aided design/computer-aided manufacturing system (CAD/CAM). Seven crowns in each group were subjected to cyclic loading at 800 N and 5 Hz in a servohydraulic testing machine until fracture or completion of 100,000 cycles. Seven finite element models comprising seven different occlusal thicknesses of 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0 mm were simulated using three different loads of vertical 800 N, oblique 10 degrees 800 N, and vertical 800 N + x N torque (x = 10, 50, and 100). The results of cyclic loading tests showed that the fracture resistance of the crown was positively associated with thickness. Specimen breakage differed significantly according to the different thicknesses of the prostheses (p < 0.01). Lowest von Mises stress values were determined for prostheses with a minimal thickness of 1.0 mm in different loading directions and with different forces. Zirconia specimens of 1.0 mm thickness had the lowest stress values and high fracture resistance and under 800 N of loading.

Fracture Strength and Precision of Fit of Implant-Retained Monolithic Zirconia Crowns

2018 ◽  
Vol 44 (5) ◽  
pp. 330-334 ◽  
Author(s):  
Pauliina Moilanen ◽  
Jenni Hjerppe ◽  
Lippo V. J. Lassila ◽  
Timo O. Närhi
Keyword(s):  
Fracture Strength ◽  
Computer Aided Design ◽  
Testing Machine ◽  
Implant Surface ◽  
Computer Aided ◽  
Cad Cam ◽  
Zirconia Crowns ◽  
Failure Loads ◽  
Monolithic Zirconia ◽  
Aided Design

New monolithic zirconia materials can be used to fabricate full-contour fixed dental prostheses with the computer-aided design/computer-aided manufacturing (CAD/CAM) method. The aim of this study was to examine the fracture strength and precision of fit of screw-retained monolithic zirconia crowns made directly on implants or by cementing on prefabricated titanium (Ti) bases. Monolithic screw-retained implant crowns (n = 6) were produced by CAD/CAM method using partially (PSZ) and fully stabilized (FSZ) zirconia. Industrially produced zirconia crowns were used as a reference. A lateral incisor study model was made onto an implant replica. Crowns were produced either directly on the implant or through cementing on a prefabricated titanium base (PSZ+Ti, FSZ+Ti). The crowns were tightened to implant replicas with a torque of 35 Ncm. The gap between the replica and the abutment or crown was measured from ×400 scanning electron microscope images for precision of fit. Mechanical testing until failure was completed with a universal testing machine with loading angle of 45°. Statistical analysis was performed (analysis of variance). Mean (±SD) failure loads were 259 ± 23 (PSZ), 140 ± 13 (FSZ), 453 ± 25 (PSZ+Ti), 439 ± 41 (FSZ+Ti), and 290 ± 39 (Procera). Mean (±SD) gap values were 2.2 ± 0.2 (PSZ), 2.5 ± 1.0 (FSZ), 7.0 ± 1.0 (PSZ+Ti), 7.7 ± 1.6 (FSZ+Ti), and 6.7 ± 1.7 (Procera). Monolithic zirconia crowns with a Ti base clearly show higher fracture strengths than the crowns fixed directly on the implant surface. Better marginal fit can be achieved with direct zirconia crowns than with crowns on a titanium base or industrially produced zirconia crowns.

scholarly journals Fracture Resistance of Monolithic Zirconia Crowns on Four Occlusal Convergent Abutments in Implant Prosthesis

2019 ◽  
Vol 9 (13) ◽  
pp. 2585 ◽  
Author(s):  
Ting-Hsun Lan ◽  
Chin-Yun Pan ◽  
Pao-Hsin Liu ◽  
Mitch M.C. Chou
Keyword(s):  
Cyclic Loading ◽  
Stress Distribution ◽  
Surface Area ◽  
Fracture Resistance ◽  
Testing Machine ◽  
Hydraulic Testing ◽  
Occlusal Surface ◽  
Von Mises Stress ◽  
Implant Abutment ◽  
Von Mises

Adjusting implant abutment for crown delivery is a common practice during implant installation. The purpose of this study was to compare the fracture resistance and stress distribution of zirconia specimens on four occlusal surface areas of implant abutment. Four implant abutment designs [occlusal surface area (SA) SA100, SA75, SA50, and SA25] with 15 zirconia prostheses over the molar area per group were prepared for cyclic loading with 5 Hz, 300 N in a servo-hydraulic testing machine until fracture or automatic stoppage after 30,000 counts. The minimum occlusal thickness of all specimens was 0.5 mm. Four finite element models were simulated under vertical or oblique 10-degree loading to analyze the stress distribution and peak value of zirconia specimens. Data were statistically analyzed, and fracture patterns were observed under a scanning electron microscope. Cyclic loading tests revealed that specimen breakage had moderately strong correlation with the abutment occlusal area (r = 0.475). Specimen breakage differed significantly among the four groups (P = 0.001). The lowest von Mises stress value was measured for prosthesis with a smallest abutment occlusal surface area (SA25) and the thickest zirconia crown. Thicker zirconia specimens (SA25) had higher fracture resistance and lowest stress values under 300 N loading.

scholarly journals Comparison of Mechanical Properties of Chairside CAD/CAM Restorations Fabricated Using a Standardization Method

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3115
Author(s):  
Myung-Sik Hong ◽  
Yu-Sung Choi ◽  
Hae-Hyoung Lee ◽  
Jung-Hwan Lee ◽  
Junyong Ahn
Keyword(s):  
Computer Aided Design ◽  
Fracture Resistance ◽  
Testing Machine ◽  
Lithium Silicate ◽  
Standardization Method ◽  
High Fracture ◽  
Failure Patterns ◽  
Fracture Failure ◽  
Computer Aided ◽  
Cad Cam

The aim of this in vitro study was to investigate the fracture resistance, fracture failure pattern, and fractography of four types of chairside computer-aided design/computer-aided manufacturing (CAD/CAM) restoration materials in teeth and titanium abutments fabricated using a standardization method. An artificial mandibular left first premolar prepared for all-ceramic crown restoration was scanned. Forty extracted mandibular molars and cylindrical titanium specimens were milled into a standardized shape. A total of eighty CAD/CAM restoration blocks were milled into a crown and twenty pieces of each lithium disilicate (LS), polymer-infiltrated-ceramic-network (PICN), resin nano ceramic (RNC), and zirconia-reinforced lithium silicate (ZLS) materials were used. Crowns were bonded to abutments, and all specimens underwent thermal cycling treatment for 10,000 cycles. Fracture resistance was measured using a universal testing machine and fracture failure patterns were analyzed using optical microscopy and scanning electron microscopy. Statistical differences were analyzed using appropriate ANOVA, Tukey HSD post hoc tests, and independent sample t-tests (α = 0.05). The results indicated that, in both teeth abutments and titanium abutments, the fracture resistances showed significantly the highest values in LS and the second highest in ZLS (p < 0.05). The fracture resistances based on teeth abutments and titanium abutments were significantly different in all the CAD/CAM restoration materials (p < 0.05). There are statistically significant correlations between the types of materials and the types of abutments (p < 0.05). Each of the different materials showed different fracture failure patterns, and there was no noticeable difference in fractographic analysis. Lithium disilicates and zirconia-reinforced lithium silicates exhibited statistically high fracture resistance, indicating their suitability as restoration materials for natural teeth or implant abutments. There were no distinct differences in the fracture pattern based on the restoration and abutment materials showed that the fracture initiated at the groove where the ball indenter was toughed and propagated toward the axial wall.

scholarly journals Effect of Reduced Occlusal Thickness with Two Margin Designs on Fracture Resistance of Monolithic Zirconia Crowns

2020 ◽  
Vol 14 (02) ◽  
pp. 245-249
Author(s):  
Haider Hasan Jasim ◽  
Meelad Basil Findakly ◽  
Nada Ali Mahdi ◽  
Mustafa Tariq Mutar
Keyword(s):  
Fracture Resistance ◽  
Testing Machine ◽  
Three Dimensional ◽  
Fracture Load ◽  
Anova Test ◽  
Optical Scanner ◽  
Nickel Chromium ◽  
Significant Difference ◽  
Zirconia Crowns ◽  
Monolithic Zirconia

Abstract Objectives The aim of this study was to compare the effects of two margin designs (shoulderless and slight chamfer) with two occlusal thicknesses on fracture resistance and failure mode of the monolithic zirconia crowns. Materials and Methods Forty nickel–chromium dies were duplicated from the previous two prepared teeth using a three-dimensional optical scanner. Nickel–chromium supporting dies were divided into two main groups (n = 20) according to the type of margin design: group A, slight chamfer margin design and group B, shoulderless margin design. These groups were further divided into two subgroups according to the occlusal thicknesses (0.5 and 1 mm). The digital imaging of each die was done using a three-dimensional optical scanner, then zirconia blocks were milled by 5-axis machine. The crowns were cleaned by alcohol, air dried, and cemented by resin cement. Next, the crowns were subjected to 500 hot and cold cycles (30 seconds for each cycle). The samples were subjected to a static load until failure using an electronic universal testing machine and fracture resistance was recorded in Newton (N). Statistical Analysis Data were analyzed using the test of normality (Shapiro–Wilk test) and two-way analysis of variance (ANOVA) test. Results  The highest mean fracture load was recorded by the shoulderless (1 mm occlusal thickness) subgroup (3,992.5 N), followed by shoulderless (0.5 mm occlusal thickness) subgroup (3,244.4 N), and the slight chamfer (1 mm occlusal thickness) subgroup (2,811 N). The lowest mean of fracture load was recorded by slight chamfer (0.5 mm occlusal thickness) subgroup (1,632.9 N). The two-way ANOVA test revealed a significant difference between the four subgroups. Regarding the fracture mode, the slight chamfer subgroups showed a severe fracture of the restoration while the shoulderless subgroups showed a fracture through the midline of the restoration. Conclusion Within the limitation of the comparative study, shoulderless margin design has a more favorable outcome than a slight chamfer design in all thicknesses. Although the restoration with reduced occlusal thickness has lower fracture resistance than 1 mm occlusal thickness, the 0.5 mm restorations still can tolerate occlusal forces.

scholarly journals Fracture Resistance and Microleakage of Endocrowns Utilizing Three CAD-CAM Blocks

2015 ◽  
Vol 40 (2) ◽  
pp. 201-210 ◽  
Author(s):  
HM El-Damanhoury ◽  
RN Haj-Ali ◽  
JA Platt
Keyword(s):  
Fracture Mode ◽  
Computer Aided Design ◽  
Fracture Resistance ◽  
Testing Machine ◽  
Resin Cement ◽  
Blue Dye ◽  
Endodontically Treated Teeth ◽  
Modes Of Failure ◽  
Computer Aided ◽  
Cad Cam

SUMMARY This study assessed marginal leakage and fracture resistance of computer-aided design/computer-aided manufacturing (CAD/CAM) fabricated ceramic crowns with intracoronal extensions into the pulp chambers of endodontically treated teeth (endocrowns) using either feldspathic porcelain (CEREC Blocks [CB], Sirona Dental Systems GmbH, Bensheim, Germany), lithium disilicate (e.max [EX], Ivoclar Vivadent, Schaan, Liechtenstein), or resin nanoceramic (Lava Ultimate [LU], 3M ESPE, St Paul, MN, USA).). Thirty extracted human permanent maxillary molars were endodontically treated. Standardized preparations were done with 2-mm intracoronal extensions of the endocrowns into the pulp chamber. Teeth were divided into three groups (n=10); each group was restored with standardized CAD/CAM fabricated endocrowns using one of the three tested materials. After cementation with resin cement, specimens were stored in distilled water at 37°C for one week, subjected to thermocycling, and immersed in a 5% methylene-blue dye solution for 24 hours. A compressive load was applied at 35 degrees to long axis of the teeth using a universal testing machine until failure. Failure load was recorded, and specimens were examined under a stereomicroscope for modes of failure and microleakage. Results were analyzed using one-way analysis of variance and Bonferroni post hoc multiple comparison tests (α=0.05). LU showed significantly (p&lt;0.05) higher fracture resistance and more favorable fracture mode (ie, fracture of the endocrown without fracture of tooth) as well as higher dye penetration than CB and EX. In conclusion, although using resin nanoceramic blocks for fabrication of endocrowns may result in better fracture resistance and a more favorable fracture mode than other investigated ceramic blocks, more microleakage may be expected with this material.

scholarly journals Fracture Load and Phase Transformation of Monolithic Zirconia Crowns Submitted to Different Aging Protocols

2016 ◽  
Vol 41 (5) ◽  
pp. E118-E130 ◽  
Author(s):  
ETP Bergamo ◽  
WJ da Silva ◽  
PF Cesar ◽  
AA Del Bel Cury
Keyword(s):  
Phase Transformation ◽  
Thermal Fatigue ◽  
Structural Reliability ◽  
Contact Point ◽  
Testing Machine ◽  
Fracture Load ◽  
Hydrothermal Aging ◽  
High Fracture ◽  
Zirconia Crowns ◽  
Monolithic Zirconia

SUMMARY Monolithic zirconia crowns have many favorable properties and may potentially be used to solve dental problems such as chipping. However, monolithic zirconia crown resistance can be affected by its phase transformation when subjected to low temperatures, humidity, and stress. This study evaluated the fracture load and phase transformation of monolithic zirconia crowns submitted to different thermal and mechanical aging tests. Seventy monolithic zirconia crowns were randomly divided into the following five groups: control, no treatment; hydrothermal aging at 122°C, two bar for one hour; thermal fatigue, 104 cycles between 5°C and 55°C, dwell time, 30 seconds; and mechanical fatigue, 106 cycles with a load of 70 N, sliding of 1.5 mm at 1.4 Hz; and combination of mechanical plus thermal fatigue. Fracture load was measured with a universal testing machine. Surface changes and fracture mode and origin were examined with a scanning electron microscope. Monoclinic phase content was evaluated by x-ray diffraction. The fracture load was analyzed using one-way analysis of variance at a level of 5%, and Weibull distribution was performed. No statistically significant differences were observed in the mean fracture load and characteristic fracture load among the groups (p&gt;0.05). The Weibull modulus ranged from 6.2 to 16.6. The failure mode was similar for all groups with the crack origin located at the contact point of the indenter. Phase transformation was shown at different surfaces of the crown in all groups (1.9% to 8.9%). In conclusion, monolithic zirconia crowns possess high fracture load, structural reliability, and low phase transformation.

Evaluation of failure of a titanium conventional plate in mandibular reconstruction and improve the performance with fibula free flap

2020 ◽  
Author(s):  
Sahand Kargarnejad ◽  
Farzan Ghalichi
Keyword(s):  
Cortical Bone ◽  
Free Flap ◽  
Computer Aided Design ◽  
Mandibular Reconstruction ◽  
Von Mises Stress ◽  
Fibula Free Flap ◽  
Computer Aided ◽  
Conventional Plate ◽  
Von Mises ◽  
Clinical Experiments

Maxillofacial extensive defects are caused by various factors such as tumor, osteomyelitis and trauma. Reconstruction of such injuries become a major challenge for maxillofacial surgeons. Clinical experiments indicate that one of the serious problems associated with conventional plate systems is the frequent incidence of complications such as screw loosening, plate exposure and plate fractures. To improve the performance of reconstruction system with new procedure. A 42-year-old male patient suffering from Ameloblastoma tumor in the lateral large defect was selected as case study. Initially, after cutting the cancerous tissue, a titanium conventional plate (TCP) model had been utilized as mandibular reconstruction system which failed due to plate exposure. Patient's CT-scan images were prepared, and geometry and shape of the plate were evaluated using Computer-Aided Design & Computer-Aided Manufacturing (CAD/CAM) and Additive Manufacturing (AM) technology. Then, its effect on the biomechanical performance of the failed system TCP model was investigated by finite element method (FEM). Fibula Free Flap FFF model as alternative and improved reconstruction system was selected. FEM evaluation of two models showed inevitable results which tip the scales in the favor of FFF model. The maximum Von-Mises stress had been exerted at the interface between screw-cortical bone. In TCP model, the peak value of Von-Mises stress exerted at the interface between screw-bone was 110 MPa, which exceeded the yield strength of the cortical bone, while, this factor fell to 68 MPa in FFF model. Furthermore, comparison with TCP model, the sensitivity of the plates and screws to the chewing load variations in FFF model decreased 20%. The results showed that the FFF model was more stable and flexible than the TCP model.

scholarly journals Fabricated CAD/CAM Post-Core Using Glass Fiber-Reinforced Resin Shows Innovative Potential in Restoring Pulpless Teeth

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6199
Author(s):  
Naoko Suzaki ◽  
Satoshi Yamaguchi ◽  
Eriko Nambu ◽  
Ryousuke Tanaka ◽  
Satoshi Imazato ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Fracture Resistance ◽  
Testing Machine ◽  
Fracture Load ◽  
Resistance Test ◽  
Fiber Reinforced ◽  
Fiber Post ◽  
Clinical Issue ◽  
Computer Aided ◽  
Cad Cam

The prevention of root fractures of pulpless teeth is an important clinical issue to maintain healthy teeth through lifetime. The aim of this study was to examine a clinically effective treatment method for strengthening vulnerable pulpless teeth using CAD/CAM (computer-aided design/computer-aided manufacturing) fiber-reinforced post-core by conducting a fracture resistance test. A post-core made with a fiber-reinforced resin disk TRINIA (TR, SHOFU, Kyoto, Japan) was fabricated using a CAD/CAM system. The fiber-layer orientation of the CAD/CAM post-core was parallel to the axis of the restored tooth. A post-core using a conventional composite and a fiber post (CF) was also prepared. A fracture resistance test of teeth restored with the post-cores and zirconia crowns was conducted using a universal testing machine, and fracture patterns were identified by micro-CT observation. The fracture load of the roots restored with TR was 1555.9 ± 231.8 N, whereas that of CF was 1082.1 ± 226.7 N. The fracture load of TR was 43.8% that was significantly higher than that of CF (Student’s t-test, p < 0.05). The restored teeth with CAD/CAM resin post-core were found to be repairable even after fracture. These results suggest that the CAD/CAM indirect fiber post-core has the potential to strengthen the vulnerable pulpless teeth.

scholarly journals Effect of Angle and Type of Customized Abutment (Castable & Cast-to) on Torque Loss and Fracture Resistance After Cyclic Loading

2018 ◽  
Vol 12 (1) ◽  
pp. 987-994
Author(s):  
Moeen Hosseini Shirazi ◽  
Maryam Memarian ◽  
Marzieh Alikhasi ◽  
Somayeh Zeighami
Keyword(s):  
Cyclic Loading ◽  
Repeated Measures ◽  
Fracture Resistance ◽  
Testing Machine ◽  
Chromium Alloy ◽  
Cobalt Chromium ◽  
High Fracture ◽  
Before And After ◽  
Torque Loss ◽  
Rotational Freedom

Background: Implant placement with more than 25° angle and use of customized abutments are still challenging in implant dentistry. Also, casting is still the most commonly used method for fabrication of customized abutments. Objective: This study evaluated the effect of angulation and type of abutment (castable and cast-to) on torque loss and fracture resistance after cyclic loading. Methods: Two implants were mounted with 0 and 30° angle on a gypsum model. Castable and Cast-to abutments were casted by cobalt-chromium alloy on each implant (10 samples in 4 groups). Rotational freedom was measured by a video-measuring microscope. The reverse torque values before and after cyclic loading (500,000 cycles) were measured by a digital torque-meter. Abutments were subjected to fracture resistance test in a universal testing machine. Data were analyzed using the Kruskal Wallis, two-way ANOVA and repeated measures tests. Results: Difference between castable and cast-to abutments regarding rotational freedom was not significant. Torque loss in castable abutments was significantly greater than cast-to abutments before and after cyclic loading (P < 0.05). The effect of abutment angle on torque loss before and after cyclic loading was not significant. Conclusion: Irrespective of the abutment angle, torque loss was significantly higher in castable groups. Considering the high fracture resistance, abutment fractures were not clinically an issue.

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