scholarly journals Impact of Quantity of Resin, C-factor, and Geometry on Resin Composite Polymerization Shrinkage Stress in Class V Restorations

2014 ◽  
Vol 39 (2) ◽  
pp. 144-151 ◽  
Author(s):  
ALS Borges ◽  
AB Borges ◽  
TA Xavier ◽  
MC Bottino ◽  
JA Platt

SUMMARY Objective This study evaluated the effect of quantity of resin composite, C-factor, and geometry in Class V restorations on shrinkage stress after bulk fill insertion of resin using two-dimensional finite element analysis. Methods An image of a buccolingual longitudinal plane in the middle of an upper first premolar and supporting tissues was used for modeling 10 groups: cylindrical cavity, erosion, and abfraction lesions with the same C-factor (1.57), a second cylindrical cavity and abfraction lesion with the same quantity of resin (QR) as the erosion lesion, and then all repeated with a bevel on the occlusal cavosurface angle. The 10 groups were imported into Ansys 13.0 for two-dimensional finite element analysis. The mesh was built with 30,000 triangle and square elements of 0.1 mm in length for all the models. All materials were considered isotropic, homogeneous, elastic, and linear, and the resin composite shrinkage was simulated by thermal analogy. The maximum principal (MPS) and von Mises stresses (VMS) were analyzed for comparing the behavior of the groups. Results Different values of angles for the cavosurface margin in enamel and dentin were obtained for all groups and the higher the angle, the lower the stress concentration. When the groups with the same C-factor and QR were compared, the erosion shape cavity showed the highest MPS and VMS values, and abfraction shape, the lowest. A cavosurface bevel decreased the stress values on the occlusal margin. The geometry factor overcame the effects of C-factor and QR in some situations. Conclusion Within the limitations of the current methodology, it is possible to conclude that the combination of all variables studied influences the stress, but the geometry is the most important factor to be considered by the operator.

2009 ◽  
Vol 16-19 ◽  
pp. 1248-1252
Author(s):  
Chun Dong Zhu ◽  
Man Chun Zhang ◽  
Lin Hua

As an important forged part of an automobile, the inner hole of the half-shaft bushing must be formed directly. However, the process requires many steps, and how the forging, or deformation, is spread over the production steps directly affects the die life and forging force required. In this paper, the three steps involved in directly forging a half shaft bushing's inner hole are simulated using the two-dimensional finite element method. Further more, we improve the forging process. From numerical calculation, the improved necessary forging force is found to be only half the original force, and the die life is doubled.


2014 ◽  
Vol 580-583 ◽  
pp. 2134-2140
Author(s):  
Jian Zhang ◽  
Jian Feng Zhai ◽  
Xian Mei Wang ◽  
Jie Chen

Two-Dimensional finite element analysis was used to investigate the performance of seawall construction over weak subgrade soil using artificial base layer material consisted of cemented sand cushion comprising geosynthetics materials. Two types of base layer materials pure sand and cemented sand comprising husk rich ash and two types of geosynthetics materials geogrid and geotextile were used. Constitutive models were used to represent different materials in numerical analysis. The competence of two-dimensional numerical analysis was compared with experimental results. Numerical results showed a superior harmony with the experimental results. Finite element analysis model proved to be a great tool to determine the parameters that are difficult to measure in laboratory experiments. In addition, finite element analysis has the benefit of cost and time saving when compared to experimental investigation work. Numerical results showed strain induced in geosynthetics eliminated beyond a distance approximately equal six times of footing width.


2020 ◽  
Vol 28 (6) ◽  
pp. 603-613 ◽  
Author(s):  
Efe Can Sivrikaya ◽  
Mehmet Sami Guler ◽  
Muhammed Latif Bekci

BACKGROUND: Zirconia has become a popular biomaterial in dental implant systems because of its biocompatible and aesthetic properties. However, this material is more fragile than titanium so its use is limited. OBJECTIVES: The aim of this study was to compare the stresses on morse taper implant systems under parafunctional loading in different abutment materials using three-dimensional finite element analysis (3D FEA). METHODS: Four different variations were modelled. The models were created according to abutment materials (zirconia or titanium) and loading (1000 MPa vertical or oblique on abutments). The placement of the implants (diameter, 5.0 × 15 mm) were mandibular right first molar. RESULTS: In zirconia abutment models, von Mises stress (VMS) values of implants and abutments were decreased. Maximum and minimum principal stresses and VMS values increased in oblique loading. VMS values were highest in the connection level of the conical abutments in all models. CONCLUSIONS: Using conical zirconia abutments decreases von Mises stress values in abutments and implants. However, these values may exceed the pathological limits in bruxism patients. Therefore, microfractures may be related to the level of the abutment.


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