Search results for "Stress analysis"
showing 10 items of 58 documents
Comparative analysis of numerical and experimental data of orthodontic mini-implants
2011
The purpose of this study was to compare numerical simulation data derived from finite element analysis (FEA) to experimental data on mini-implant loading. Nine finite element (FE) models of mini-implants and surrounding bone were derived from corresponding experimental specimens. The animal bone in the experiment consisted of bovine rib. The experimental groups were based on implant type, length, diameter, and angle of insertion. One experimental specimen was randomly selected from each group and was digitized in a microCT scanner. The FE models consisted of bone pieces containing Aarhus mini-implants with dimensions 1.5 × 7 mm and 1.5 × 9 mm or LOMAS mini-implants (dimensions 1.5 × 7 mm, …
Biomechanical behavior of cavity configuration on micropush-out test: A finite-element-study
2009
Objective: The objective of this study was to simulate the micropush-out bond strength test from a biomechanical point of view. For this purpose, stress analysis using finite element (FE) method was performed. Study design: Three different occlusal cavity shapes were simulated in disc specimens (model A: 1.5 mm cervical, 2 mm occlusal diameter; model B: 1.5 mm cervical, 1.75 mm occlusal diameter; model C: 1.5 mm cervical, 1.5 mm occlusal diameter). Quarter sizes of 3D FE specimen models of 4.0×4.0×1.25 mm3 were constructed. In order to avoid quantitative differences in the stress value in the models, models were derived from a single mapping mesh pattern that generated 47.182 elements and 6…
Influence of prefabricated post material on restored teeth: fracture strength and stress distribution.
2006
This work studied how prefabricated intraradicular post material affects the mechanical performance of restored teeth. The effect of using two different materials (glass fiber and stainless steel) with significantly different elastic moduli was studied.A combined theoretical and experimental method was used: first, an experimental fracture strength test was performed on 60 extracted human maxillary central incisors. The teeth were decoronated, treated endodontically and restored, 30 with glass fiber posts and 30 with stainless steel posts. The data were recorded and the results compared using an ANOVA test. Then, the finite element technique was used to develop a model of the restored tooth…
Comparative fracture behavior of monolithic and veneered zirconia posterior fixed dental prostheses
2017
The purpose of this study was to evaluate and to compare the fracture load and the fracture pattern of monolithic and veneered zirconia posterior fixed dental prostheses (FDPs). Twenty standardized steel dies were prepared to receive posterior 3-unit FDPs. Specimens were randomly divided into 2 groups (n=10): (1) Lava Zirconia, and (2) Lava Plus. All FDPs were cemented using glass ionomer cement and subjected to thermal and mechanical cycling at 5-55ºC with a 30-s dwell time for 120,000 masticatory cycles. All specimens were subjected to a three-point bending test until fracture. Data were statistically analyzed using Student's t test, paired t-test and Weibull statistics (α=0.05). No diffe…
Effect of Thermomechanical and Static Loading on the Load to Fracture of Metal‐Ceramic, Monolithic and Veneered Zirconia Posterior Fixed Partial Dent…
2018
PURPOSE To evaluate the influence of static (not preloaded) and thermomechanical loading on the load to fracture of metal-ceramic, monolithic and veneered zirconia computer-aided design/computer-aided manufacturing (CAD/CAM) posterior fixed partial dentures (FPDs). MATERIALS AND METHODS One hundred standardized specimens with 2 abutments screwed onto a platform were prepared from stainless steel to receive a posterior 3-unit FPD with an intermediate pontic. Specimens were randomly divided into 5 groups (n = 20): Metal-ceramic (control group), Lava Zirconia system, Vita In-Ceram YZ, IPS e.max ZirCAD, and Lava Plus. Half of the specimens of each group (n = 10) underwent no preloading, and the…
Disinclusion of unerupted teeth by mean of self-ligating brackets: Effect of blood contamination on shear bond strength
2012
Objectives: The aim of this study was to assess the effect of blood contamination on the shear bond strength and failure site of three different orthodontic self-ligating brackets. Study Design: 240 bovine permanent mandibular incisors were randomly divided into 12 groups of 20 specimens each. Orthodontic self-ligating brackets were tested under four different enamel surface conditions: a) dry, b) blood contamination before priming, c) blood contamination after priming, d) blood contamination before and after priming. Brackets were bonded to the teeth and subsequently tested using a Instron universal testing machine. Shear bond strength values and adhesive failure rate were recorded. Statis…
Retentive strengths of cast gold crowns using glass ionomer, compomer, or resin cement
1998
The retention forces of a newly developed compomer cement (Dyract Cem), a glass ionomer cement (Ketac Cem Aplicap), and a resin cement (F21) were examined.Cemented cast gold crowns were removed along the path of insertion with a Zwick universal testing device. The impact of both a cured and a noncured additional bonding layer that were applied to the inner surface of the crowns was examined across the Dyract Cem group.The mean adhesive strength was measured at 2.36 +/- 0.69 N/mm2 in the Ketac Cem group, at 0.60 +/- 0.28 N/mm2 in the F21 group, and at 1.85 +/- 0.94 N/mm2 in the Dyract Cem group, respectively. The application of an additional bonding layer to the inner surface of the crowns d…
Influence of prefabricated post dimensions on restored maxillary central incisors
2007
summary The aim of this study was to test the following hypothesis: biomechanical performance (fracture strength and stress distribution) of restored teeth is less sensitive to post diameter and post length when using glass fibre posts than when using stainless steel posts. First, an experimental fracture strength test was performed on 80 extracted human maxillary central incisors. Teeth were decoronated, treated endodontically and restored (40 with glass fibre posts and 40 with stainless steel posts), and the length and diameter of the posts varied uniformly. Failure loads were recorded and results were compared using an ancova analysis. Secondly, the finite element technique was used to …
In vitro retentive strength of zirconium oxide ceramic crowns using different luting agents
2005
Statement of problem In contrast to gold crowns, in vitro determination of the retentive strength of all-ceramic crowns is more difficult because components allowing connection to testing apparatus are not as easily integrated into the all-ceramic material. Nevertheless, retentive strength data are crucial for obtaining information about the potential clinical performance of luting cements for all-ceramic restorations. Therefore, a new in vitro model was necessary to evaluate the retentive strength of all-ceramic crowns. Purpose The purpose of this in vitro study was to determine the retentive strength of 4 resin-cement systems, a compomer, a glass-ionomer cement, a resin-modified glass-ion…
Premolars restored with posts of different materials: fatigue analysis
2011
Previous works studied the effect of the material and the dimensions of the post on the biomechanical performance (fracture strength and stress distribution) of restored teeth, under static loads. The aim of this work was to study the effect of the post material (glass fibre and stainless steel) on restored teeth, which have the final crown, under dynamic conditions. The use of a biomechanical model, including a fatigue analysis from FEA, is presented as a powerful method to study the effect of the material of the intraradicular post. The inclusion of the fatigue analysis allows for a more realistic study that takes into account the dynamic nature of masticatory forces. At the same time, th…