scholarly journals Post-gel shrinkage, elastic modulus, and stress generated by orthodontic adhesives

2019 ◽  
Vol 90 (2) ◽  
pp. 278-284
Author(s):  
Michael J. Rasmussen ◽  
Cameron Togrye ◽  
Terry M. Trojan ◽  
Daranee Tantbirojn ◽  
Antheunis Versluis
Keyword(s):  
Elastic Modulus ◽  
Flexural Strength ◽  
Color Change ◽  
Bending Test ◽  
Shrinkage Stress ◽  
Element Analysis ◽  
Cross Sectional ◽  
Test Analysis ◽  
Orthodontic Adhesives ◽  
Post Hoc

ABSTRACT Objectives: To measure post-gel shrinkage, elastic modulus, and flexural strength of orthodontic adhesives and to predict shrinkage stress using finite element analysis (FEA). Materials and Methods: The following 6 orthodontic adhesives were tested: Transbond XT (3M Unitek, Monrovia, Calif), Transbond Plus Color Change (3M Unitek), Greengloo (Ormco, Brea, Calif), Ortho Connect (GC America, Alsip, Ill), Trulock (RMO, Denver, Colo), GoTo (Reliance, Itasca, Ill). Post-gel shrinkage was measured using a biaxial strain gauge during light curing. Elastic modulus and flexural strength were measured with a 4-point bending test. Analysis of variance and Student-Newman-Keuls post hoc tests were used to compare the shrinkage, elastic modulus, and flexural strengths among the materials (α = .05). Shrinkage stresses caused by the post-gel shrinkage and elastic modulus values were calculated using a cross-sectional FEA of a metallic bracket bonded to an incisor. Results: Properties were highly different among the adhesives (P ≤ .0001). Transbond XT (0.38 ± 0.09 percent volumetric contraction) and GoTo (0.42 ± 0.05 percent volumetric contraction) had the lowest post-gel shrinkage; Transbond Plus Color Change had the highest (0.84 ± 0.08 percent volumetric contraction). OrthoConnect (6.8 ± 0.6 gigapascals) had the lowest elastic modulus; GoTo (28.3 ± 3.1 gigapascals) had the highest. Trulock (64.1 ± 8.2 megapascals) had the lowest flexural strength; Greengloo (139.1 ± 20.7 megapascals) had the highest. FEA showed that the highest shrinkage stresses were generated with Transbond Plus Color Change and the lowest with OrthoConnect. Conclusions: Post-gel shrinkage of orthodontic adhesives was comparable with restorative composites, which are known to create shrinkage stresses in restored teeth. FEA indicated that this shrinkage creates stresses in the adhesive and in the enamel around the brackets.

scholarly journals Effect of Camphorquinone Concentration in Physical-Mechanical Properties of Experimental Flowable Resin Composites

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Dayany da Silva Alves Maciel ◽  
Arnaldo Bonfim Caires-Filho ◽  
Marta Fernandez-Garcia ◽  
Camillo Anauate-Netto ◽  
Roberta Caroline Bruschi Alonso
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Flexural Strength ◽  
Mechanical Strength ◽  
Surface Hardness ◽  
Degree Of Conversion ◽  
Bending Test ◽  
Resin Matrix ◽  
Shrinkage Stress ◽  
Depth Of Cure

The aim of this study was to evaluate the effect of camphorquinone concentration in physical-mechanical properties of experimental flowable composites in order to find the concentration that results in maximum conversion, balanced mechanical strength, and minimum shrinkage stress. Model composites based on BISGMA/TEGDMA with 70% wt filler loading were prepared containing different concentrations of camphorquinone (CQ) on resin matrix (0.25%, 0.50%, 1%, 1.50%, and 2% by weight). Degree of conversion was determined by FTIR. Surface hardness was assessed before and after 24 h ethanol storage and softening rate was determined. Depth of cure was determined by Knoop hardness evaluation at different depths. Color was assessed by reflectance spectrophotometer, employing the CIE-Lab system. Flexural strength and elastic modulus were determined by a three-point bending test. Shrinkage stress was determined in a Universal Testing Machine in a high compliance system. Data were submitted to ANOVA and Tukey’s test (α = 0.05). The increase in CQ concentration caused a significant increase on flexural strength and luminosity of composites. Surface hardness was not affected by the concentration of CQ. Composite containing 0.25% wt CQ showed lower elastic modulus and shrinkage stress when compared to others. Depth of cure was 3 mm for composite containing 1% CQ and 2 mm for the other tested composites. Degree of conversion was inversely correlated with softening rate and directly correlated with elastic modulus and shrinkage stress. In conclusion, CQ concentration affects polymerization characteristics and mechanical strength of composites. The concentration of CQ in flowable composite for optimized polymerization and properties was 1% wt of the resin matrix, which allows adequate balance among degree of conversion, depth of cure, mechanical properties, and color characteristics of these materials.

scholarly journals Flexural Strength of Glass Carbomer Cement and Conventional Glass Ionomer Cement Stored in Different Storage Media over Time

2018 ◽  
Vol 27 (4) ◽  
pp. 372-377 ◽  
Author(s):  
Muhammad Ali Faridi ◽  
Abdul Khabeer ◽  
Saad Haroon
Keyword(s):  
Flexural Strength ◽  
Artificial Saliva ◽  
Glass Ionomer Cement ◽  
Bending Test ◽  
Glass Ionomer ◽  
Time Intervals ◽  
Storage Media ◽  
Unique Factor ◽  
Post Hoc ◽  
Ionomer Cement

Objectives: Glass ionomer cement (GIC) is routinely placed as a restorative material in dentistry. However, due to its poor physical properties, its use is limited to cases where the level of stress on restoration is minimal. Improved formulations of GIC have been developed to overcome these drawbacks. The purpose of this study was to evaluate flexural strength of a conventional GIC (Fuji IX) against a newly developed glass carbomer cement (GCP). Materials and Methods: For Fuji IX and GCP, a total of 80 blocks were prepared and divided into 16 groups (n = 5). These groups were further categorized according to the storage medium (artificial saliva and Vaseline) and time intervals (24 h and 1, 2, and 4 weeks). A 3-point bending test was carried out, and statistical analysis was done using ANOVA and Tukey post hoc tests. Results: Fuji IX showed a mean flexural strength of 25.14 ± 13.02 versus 24.27 ± 12.57 MPa for GCP. There was no significant statistical difference between both materials when compared under storage media. Both materials showed the highest value for flexural strength at 2 weeks of storage and lowest at 4 weeks. Conclusion: The storage media do not affect the flexural strength of the specimens with reference to time. Time is the unique factor with relative influence on mean resistance to fracture. Further testing is required to evaluate the true potential of the newly developed GCP.

scholarly journals Effects of SiO2 Incorporation on the Flexural Properties of a Denture Base Resin: An In Vitro Study

2021 ◽  
Author(s):  
Sara T. Alzayyat ◽  
Ghadah A. Almutiri ◽  
Jawhara K. Aljandan ◽  
Raneem M. Algarzai ◽  
Soban Q. Khan ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Flexural Strength ◽  
Testing Machine ◽  
Base Material ◽  
Bending Test ◽  
Control Group ◽  
Denture Base ◽  
Nano Sio2 ◽  
Base Resin ◽  
Denture Base Resin

Abstract Objective The aim of this study was to evaluate the effects of the addition of low-silicon dioxide nanoparticles (nano-SiO2) on the flexural strength and elastic modulus of polymethyl methacrylate (PMMA) denture base material. Materials and Methods A total of 50 rectangular acrylic specimens (65 × 10 × 2.5 mm3) were fabricated from heat-polymerized acrylic resin. In accordance with the amount of nano-SiO2, specimens were divided into the following five groups (n = 10 per group): a control group with no added SiO2, and four test groups modified with 0.05, 0.25, 0.5, and 1.0 wt% nano-SiO2 of acrylic powder. Flexural strength and elastic modulus were measured by using a 3-point bending test with a universal testing machine. A scanning electron microscope was used for fracture surface analyses. Data analyses were conducted through analysis of variance and Tukey’s post hoc test (α = 0.05). Results Compared with the control group, flexural strength and modulus of elasticity tended to significantly increase (p ˂ 0.001) with the incorporation of nano-SiO2. In between the reinforced groups, the flexural strength significantly decreased (p ˂ 0.001) as the concentrations increased from 0.25 to 1.0%, with the 1.0% group showing the lowest value. Furthermore, the elastic modulus significantly increased (p ˂ 0.001) at 0.05% followed by 1.0%, 0.25%, 0.5%, and least in control group. Conclusion A low nano-SiO2 addition increased the flexural strength and elastic modulus of a PMMA denture base resin.

Effect of Filler Content and Waiting time Before Light-Curing on Mechanical Properties of Dual-Cured Cement

2020 ◽  
Vol 2 (1) ◽  
pp. 45-52
Author(s):  
Ana C. de Assunção Oliveira ◽  
Sandro Griza ◽  
Rafael R. de Moraes ◽  
André L. Faria-e-Silva
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Flexural Strength ◽  
Waiting Time ◽  
Filler Content ◽  
Bending Test ◽  
Resin Cements ◽  
Three Point Bending ◽  
Light Curing ◽  
Curing Procedure

Objective:: To investigate the effect of filler content and the time spent before light-curing on mechanical properties of dual-cured cement. Methods:: Experimental dual-cured resin cements were formulated with 60, 65 or 68wt% of filler. The viscosity of experimental cement was measured using a digital viscometer. Bar-shaped specimens (25 x 2 x 2 mm) were fabricated, while the light-curing was started immediately or 5 minutes after the insertion of cement into the mold (n = 7). A three-point bending test was performed and the values of flexural strength and elastic modulus were measured. The Vickers hardness of fractured specimens was measured on the surface of the cement. Data from viscosity were submitted to oneway ANOVA, while the data from mechanical properties were analyzed by two-way ANOVA. All pair-wise comparisons were performed using Tukey’s test (α = 0.05). Results:: The experimental cement with 68wt% of filler showed the highest viscosity and those with 60wt% showed the the lowest viscosity. Irrespective of the time spent before light-curing, the cement with 65wt% of filler presented the highest values of flexural strength and elastic modulus. The addition of 60wt% of filler resulted in the lowest elastic modulus, while 68wt% of filler resulted in lowest flexural strength. Regarding the hardness, the cement with 68wt% of filler showed the highest values, while there was no difference between 60 and 65wt% of filler. Conclusion:: Filler content affected the mechanical properties of the experimental cement and this effect did not depend on the waiting time before the light-curing procedure.

Mechanical Properties and Simulated Wear of Provisional Resin Materials

2015 ◽  
Vol 40 (6) ◽  
pp. 603-613 ◽  
Author(s):  
T Takamizawa ◽  
WW Barkmeier ◽  
A Tsujimoto ◽  
D Scheidel ◽  
RL Erickson ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Elastic Modulus ◽  
Flexural Strength ◽  
Wear Behavior ◽  
Flexural Properties ◽  
Wear Depth ◽  
Volume Loss ◽  
Significant Difference ◽  
Post Hoc ◽  
Pmma Resin

SUMMARY The purpose of this study was to determine flexural properties and erosive wear behavior of provisional resin materials. Three bis-acryl base provisional resins—1) Protemp Plus (PP), 2) Integrity (IG), 3) Luxatemp Automix Plus (LX)—and a conventional poly(methylmethacrylate) (PMMA) resin, UniFast III (UF), were evaluated. A resin composite, Z100 Restorative (Z1), was included as a benchmark material. Six specimens for each of the four materials were used to determine flexural strength and elastic modulus according to ISO Standard 4049. Twelve specimens for each material were used to examine wear using a generalized wear simulation model. The test materials were each subjected to wear challenges of 25,000, 50,000, 100,000, and 200,000 cycles in a Leinfelder-Suzuki (Alabama) wear simulator. The materials were placed in custom cylinder-shaped stainless-steel fixtures, and wear was generated using a cylindrical-shaped flat-ended stainless-steel antagonist in a slurry of nonplasticized PMMA beads. Wear (mean facet depth [μm] and volume loss [mm3]) was determined using a noncontact profilometer (Proscan 2100) with Proscan and AnSur 3D software. The laboratory data were evaluated using two-way analysis of variance (ANOVA; factors: 1) material and 2) cycles) followed by Tukey HSD post hoc test (α=0.05). The flexural strength ranged from 68.2 to 150.6 MPa, and the elastic modulus ranged from 2.0 to 15.9 GPa. All of the bis-acryl provisional resins (PP, IG, and LX) demonstrated significantly higher values than the PMMA resin (UF) in flexural strength and elastic modulus (p<0.05). However, there was no significant difference (p>0.05) in flexural properties among three bis-acryl base provisional resins (PP, IG, and LX). Z1 demonstrated significantly (p<0.05) higher flexural strength and elastic modulus than the other materials tested. The results for mean facet wear depth (μm) and standard deviations (SD) for 200,000 cycles were as follows: PP, 22.4 (5.0); IG, 51.0 (6.5); LX, 63.7 (4.5); UF, 70.5 (8.0); and Z1, 7.6 (1.2). Volume loss (mm3) and SDs for 200,000 cycles were as follows: PP, 0.311 (0.049); IG, 0.737 (0.074); LX, 0.919 (0.053); UF, 1.046 (0.127); and Z1, 0.111 (0.017). The two-way ANOVA showed a significant difference among materials (p<0.001) and number of cycles for both facet depth and volume loss. The post hoc test revealed differences (p<0.05) in wear values among the tested materials examined in this study. The findings provide valuable information regarding the flexural properties and the relative wear behavior of the provisional resins examined in this study.

scholarly journals Effect of Glazing on Flexural Strength of Full-Contour Zirconia

2018 ◽  
Vol 2018 ◽  
pp. 1-5 ◽  
Author(s):  
Hattanas Kumchai ◽  
Patrapan Juntavee ◽  
Arthur F. Sun ◽  
Dan Nathanson
Keyword(s):  
Flexural Strength ◽  
Significant Influence ◽  
Testing Machine ◽  
Surface Treatments ◽  
Bending Test ◽  
Three Point Bending ◽  
Universal Testing ◽  
Heat Treated ◽  
Significant Difference ◽  
Post Hoc

Objective. The purpose of this study was to evaluate the effect of glazing on flexural strength of highly translucent zirconia materials. Materials and Methods. Specimens of three brands of zirconia bars (Prettau Zirconia, Zirkonzahn; inCoris TZI, Sirona; and Zirlux FC, Pentron Ceramics) were prepared and polished according to manufacturers’ instructions. Final specimen dimensions were 20 × 4 × 2 mm. The specimens from each brand were divided into 3 groups (N = 10): control, heat-treated, and glazed. Heat-treated specimens were fired without the application of the glaze material. The glaze material was applied to the glazed specimens before being fired. A three-point bending test (15 mm span) was performed in an Instron universal testing machine (ISO 6872). Data were analyzed by ANOVA and Tukey’s HSD post hoc test (α = 0.05). Results. Two-way ANOVA showed a significant influence of surface treatments on flexural strength of zirconia materials (P≤0.05). There was no significant difference in flexural strength among the different brands of highly translucent zirconia (P≥0.05). Tukey’s HSD post hoc test showed that specimens in the “glazed” group had significantly lower flexural strength than the control and heat-treated groups (P≤0.05). Conclusion. Within the limitations of the study, external glazing decreased the flexural strength of highly translucent zirconia.

Flexural Performance of Polyurethane/Multi Walled Carbon Nanotubes Foam Composites

2015 ◽  
Vol 754-755 ◽  
pp. 8-12 ◽  
Author(s):  
A.A. Sinar ◽  
Zainuddin Firuz ◽  
M.A. Nur Azni ◽  
M.A. Hazizan ◽  
H.A. Sahrim
Keyword(s):  
Carbon Nanotubes ◽  
Flexural Strength ◽  
Sandwich Composites ◽  
Multiwalled Carbon ◽  
Element Analysis ◽  
Test Analysis ◽  
Average Value ◽  
Pu Foam ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Polyurethane (PU)/multiwalled carbon nanotubes (MWCNTs) foam composites were produced by reaction of based palm oil polyol (POP) with methylene diphenyl diisocyanate (MDI). The MWCNTs were added into PU foam with the percentages varied from 0 wt.% to 3 wt.%. Sandwich composites were prepared using hand lay-up method where Aluminium (Al) sheet as skin were stacked onto PU foam using Araldite adhesives. The PU/MWCNTs foam composites (PMFC) and PU/MWCNTs foam sandwich composites (PMFSC) were characterized using flexural test analysis. Observation showed higher value of flexural strength for PMFC and PMFSC at 0.5% incorporation of MWCNTs. The flexural strength of sandwich PU foam is higher with an average value of 159.38% than control PU foam, due to Al sheet act as ductile skin and prevents samples from rupture rapidly. The modeling using finite element analysis (NX Software-version 8.5) showed the displacement nodal magnitude for 0.5% PMFC (2.537 mm) are higher than 0.5% PMFSC (0.288 mm).

Experimental and simulation studies on flexural strength of laminated glass using ring-on-ring and three-point bending test

2017 ◽  
Vol 232 (21) ◽  
pp. 3930-3941 ◽  
Author(s):  
Ajitanshu Vedrtnam ◽  
SJ Pawar
Keyword(s):  
Flexural Strength ◽  
Layer Thickness ◽  
Vinyl Acetate ◽  
Load Capacity ◽  
Polyvinyl Butyral ◽  
Bending Test ◽  
Laminated Glass ◽  
Element Analysis ◽  
Ethyl Vinyl ◽  
Three Point Bending

Flexural strength of laminated glass is noteworthy in architectural, glazing, automotive safety, photo-voltaic, and decorative applications. The flexural strength of laminated glass samples having polyvinyl butyral/ethyl vinyl acetate interlayer of different critical thickness (0.38/0.76/1.52 mm) was determined by ring-on-ring test following the ASTM C1499-15 and also by three-point bending test (for an interlayer of 0.38 mm thickness) following the ASTM D790-03. The effect of inter-layer type and inter-layer thickness on flexural strength is evidently reported from this brief study. The significance F-statics value during regression analysis shows the strong association of flexural strength with inter-layer types and inter-layer thickness, and P-value shows that the error in the analysis is within considerable limits. It is also concluded that the laminated glass samples with polyvinyl butyral interlayer have comparatively lower load capacity than laminated glass samples with ethyl vinyl acetate interlayer for same interlayer and glass thickness. The inter-layer thickness has more prominent role in the determination of load capacity in case of ethyl vinyl acetate laminated glass samples. There is an increment in average load capacity with an increment in critical inter-layer thickness in laminated glass. A finite element analysis is also carried out for simulating the experimentation and obtaining the variation of displacements in the laminated glass samples at their load capacity. The output of the finite element analysis fairly describes the fracture pattern (based on deformation and stress) of the laminated glass samples. The conclusions may be utilized for the selection of suitable laminated glass and predicting failure of laminated glass while used in various structural, automotive and other applications.

Effects of Pretreatment, Specimen Thickness, and Artificial Aging on Biaxial Flexural Strength of Two Types of Y-TZP Ceramics

2019 ◽  
Vol 44 (6) ◽  
pp. 615-624
Author(s):  
A Sundh ◽  
W Kou ◽  
G Sjögren
Keyword(s):  
Flexural Strength ◽  
Surface Treatment ◽  
Pearson Correlation ◽  
Tetragonal Zirconia ◽  
Specimen Thickness ◽  
Test Analysis ◽  
Heat Treated ◽  
Biaxial Flexural Strength ◽  
Correlation Tests ◽  
Post Hoc

SUMMARYObjectives:To evaluate the effects of surface treatment, specimen thickness, and aging on the biaxial flexural strength (BFS) of two types of yttria-stabilized, tetragonal zirconia polycrystal (Y-TZP) ceramics.Methods and Materials:Disc-shaped specimens, 0.4 and 1.3 mm thick, made from hot isostatic pressed (Denzir) and non–hot isostatic pressed (ZirPlus) Y-TZP, were sandblasted, heat treated, and autoclaved. The surface topography was assessed in accordance with European Standard 623-624:2004 and the BFS tests in accordance with International Organization for Standardization Standard 6872:2008. For statistical analyses, one-way Shapiro-Wilk test, analysis of variance (post hoc: least significant differences), Mann-Whitney U-test, and Pearson correlation tests (p<0.05) were used.Results:As delivered, the BFS of the 0.4-mm ZirPlus was >1.3-mm ZirPlus (p<0.01), and the BFS of the 0.4-mm Denzir was >1.3-mm Denzir (p<0.001). Sandblasting with 0.2 MPa reduced the BFS of the ZirPlus and Denzir discs (p<0.01), whereas sandblasting with 0.6 MPa increased the BFS of the 0.4-mm Denzir (p<0.001) and reduced the BFS of the 0.4-mm ZirPlus (p<0.05). Heat treatment significantly reduced the BFS of all the groups except for the 0.6 MPa sandblasted 0.4-mm ZirPlus. Autoclaving reduced the BFS of the as-delivered ZirPlus and Denzir specimens (p<0.001), whereas autoclaving the 0.6 MPa sandblasted and heat-treated specimens had no effect (p>0.05) on the BFS. The 0.6 MPa sandblasted, heat-treated, and autoclaved 0.4-mm Denzir exhibited higher BFS than the 0.6 MPa sandblasted, heat-treated, and autoclaved 0.4-mm ZirPlus (p<0.05).Conclusions:Thickness and surface treatment of Y-TZP–based ceramics should be considered since those factors could influence the BFS of the material.

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