scholarly journals Fatigue resistance and 3D finite element analysis of machine-milled ceramic occlusal veneers with new preparation designs versus conventional design: an in vitro study

F1000Research ◽  
2019 ◽  
Vol 8 ◽  
pp. 1038 ◽  
Author(s):  
Samaa Kotb ◽  
Atef Shaker ◽  
Carl Halim
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Resistance ◽  
Element Analysis ◽  
3D Finite Element ◽  
Group Iii ◽  
Conventional Design ◽  
Group I ◽  
Group Ii ◽  
Preparation Design

Background: Treatment of patients with severe tooth wear is complex. Treatments involving more tooth structure removal may be inappropriate for patients who have already lost a significant amount of dental tissue due to erosion. The aim of this study was to evaluate the effect of two modified occlusal veneer preparations on the fatigue resistance and stress distribution of bonded occlusal veneers, in comparison to the conventional preparation design. Methods: A total of 54 human mandibular molars were distributed into three equal groups of n=18 teeth each, according to the occlusal veneer preparation design, where group I (conventional design) received Planar occlusal veneer preparation, group II (occlusal veneer with circumferential finish line) and group III (occlusal veneer with intracoronal cavity extension). For the manufacture of all the veneers using machinable zirconium lithium silicate glass ceramic blocks, a computer aided design/manufacturing system was used. A dual cure, adhesive resin cement was used to bond all occlusal veneers to corresponding prepared teeth. After storage in water for one week, step-stress (accelerated life testing was performed for all samples. Finite element analysis was carried out as well to evaluate the distribution of stresses. Results: The highest values (mean±SD) were recorded for group II (890.57±211.53 N) followed by Group I values (883.54±135.91 N), while the lowest values were recorded for Group III (875.57±143.52 N). The difference between groups was statistically non-significant as indicated by ANOVA (P=0.9814>0.05). The stress values were generally found to be low and their distribution differed among groups. Conclusion: Group I and II showed comparable fatigue resistance and more favourable failure behaviour when compared to Group III based on the fractographic and 3D finite element analyses.

scholarly journals Fracture resistance and 3D finite element analysis of machined ceramic crowns bonded to endodontically treated molars with two planes versus flat occlusal preparation designs: an in vitro study

F1000Research ◽  
2021 ◽  
Vol 8 ◽  
pp. 1020
Author(s):  
Omnia Nabil ◽  
Carl Hany Halim ◽  
Ashraf Hassan Mokhtar
Keyword(s):  
Stress Distribution ◽  
Fracture Resistance ◽  
Element Analysis ◽  
3D Finite Element ◽  
Mean Values ◽  
Group I ◽  
Group Ii ◽  
The Impact ◽  
Preparation Design ◽  
Distribution Of Stresses

Background: The flat occlusal preparation design (FOD) of posterior teeth offers promising results of fracture resistance and stress distribution, but its application in vital teeth is limited as there may be a danger of pulp injury. Although this danger is omitted in endodontically treated teeth, there is no research work assessing the impact of FOD on the fracture resistance and distribution of stresses among these teeth. The aim of this study was to assess the impact of FOD of endodontically treated molars on the fracture resistance and distribution of stresses among a ceramic crown-molar structure when compared to the two planes occlusal preparation design (TOD). Methods: 20 human mandibular molars were endodontically treated and distributed equally to two groups: Group I (TOD) and Group II (FOD). Ceramic CAD/CAM milled lithium disilicate (IPS e.max CAD) crowns were produced for all preparations and adhered using self-adhesive resin cement. Using a universal testing machine, the fracture resistance test was performed. The fractured samples were examined using a stereomicroscope and scanning electron microscope to determine modes of failure. Stress distribution was evaluated by 3D finite element analysis, which was performed on digital models of endodontically treated mandibular molars (one model for each design). Results: Group II recorded statistically non-significant higher fracture resistance mean values (3107.2± 604.9 N) than Group I mean values (2962.6 ±524.27 N) as indicated by Student’s t-test (t=0.55, p= 0.57). Also, Group II resulted in more favorable failure mode as compared to Group I. Both preparation designs yielded low von-Mises stresses within the factor of safety. However, the stress distribution among different layers of the model differed. Conclusions: FOD having comparable fracture strength to TOD and a more favorable fracture behavior can be used for the preparation of endodontically treated molars.

scholarly journals Fracture resistance and 3D finite element analysis of machined ceramic crowns bonded to endodontically treated molars with two planes versus flat occlusal preparation designs: an in vitro study

F1000Research ◽  
2019 ◽  
Vol 8 ◽  
pp. 1020 ◽  
Author(s):  
Omnia Nabil ◽  
Carl Hany Halim ◽  
Ashraf Hassan Mokhtar
Keyword(s):  
Stress Distribution ◽  
Fracture Resistance ◽  
Element Analysis ◽  
3D Finite Element ◽  
Mean Values ◽  
Group I ◽  
Group Ii ◽  
The Impact ◽  
Preparation Design ◽  
Distribution Of Stresses

Background:The flat occlusal preparation design (FOD) of posterior teeth offers promising results of fracture resistance and stress distribution, but its application in vital teeth is limited as there may be a danger of pulp injury. Although this danger is omitted in endodontically treated teeth, there is no research work assessing the impact of FOD on the fracture resistance and distribution of stresses among these teeth. The aim of this study was to assess the impact of FOD of endodontically treated molars on the fracture resistance and distribution of stresses among a ceramic crown-molar structure when compared to the two planes occlusal preparation design (TOD).Methods:20 human mandibular molars were endodontically treated and distributed equally to two groups: Group I (TOD) and Group II (FOD). Ceramic CAD/CAM milled lithium disilicate (IPS e.max CAD) crowns were produced for all preparations and adhered using self-adhesive resin cement. Using a universal testing machine, the fracture resistance test was performed. The fractured samples were examined using a stereomicroscope and scanning electron microscope to determine modes of failure. Stress distribution was evaluated by 3D finite element analysis, which was performed on digital models of endodontically treated mandibular molars (one model for each design).Results:Group II recorded statistically non-significant higher fracture resistance mean values (3107.2± 604.9 N) than Group I mean values (2962.6 ±524.27 N) as indicated by Student’s t-test (t=0.55, p= 0.57). Also, Group II resulted in more favorable failure mode as compared to Group I. Both preparation designs yielded low von-Mises stresses within the factor of safety. However, the stress distribution among different layers of the model differed.Conclusions:FOD having comparable fracture strength to TOD and a more favorable fracture behavior can be used for the preparation of endodontically treated molars.

scholarly journals Biomechanical Analysis of the Zirconia and Graphene-based CAD-CAM Dental Bridges at Different Pontic Length: A Finite Element Analysis

2020 ◽  
Author(s):  
Mohammed Sulaiman Alruthea
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Normal Stress ◽  
Elastic Strain ◽  
Biomechanical Analysis ◽  
Total Deformation ◽  
Element Analysis ◽  
Group Iii ◽  
Group I ◽  
Bridge Group

Introduction: During masticatory loading, dental bridges are subjected to various forces that might generate deflections in the bridge framework. For this reason, designing long-span bridges require great care about flexions that happen during the function. This can be compensated by increasing occluso-gingival height, using rigid materials and enhancing resistance to deflection by modifying the abutments’ preparations. The current study hypothesied that the stress, deflection, strain and deformation of the fixed partial dentures are guided by the three-dimensional configurations of the pontic areas, and all other parameters could be mutually changed with different influence on the overall outcome. Aim: The study aimed to evaluate the difference in the amount of stress, deflection, strain and deformation on using different materials and configurations in the pontic and connector area of the dental bridge using the 3D Finite Element Analysis (FEA). Materials and Methods: An invitro virtual biomechanical analysis using 3D FEA method was conducted. 3D models were created from the Cone Beam Computed Tomography (CBCT) of a dentulous patient and two materials were selected for this study, Zirconia and enhanced graphene-based polymer. The study models were assembled into four groups as the following: Group I: 3-unit Zirconia fixed-fixed bridge; Group II: 3-unit Graphene fixed-fixed bridge; Group III: 4-unit Zirconia fixed-fixed bridge; Group IV: 4-unit Graphene fixed-fixed bridge. Using FEA software a 600 N load was applied and the resultant normal stress, deflection, maximum equivalent strain and total deformation data were monitored, collected and interpreted. Results: The findings of the current study showed higher values of normal stress, deflection, equivalent elastic strain and total deformation in Graphene-based bridges (group II and IV) than the Zirconia-based bridges (group I and III). It should also be mentioned that normal stress, deflection, equivalent elastic strain, and total deformation showed higher values in the three-unit bridge (group I and II) than their corresponding 4-unit bridge groups (group III and IV). Conclusion: This biomechanical analysis confirmed that the stress concentration and deflection of the fixed bridge are influenced by material characteristics. However, configuration of the pontic area could influence the studied mechanical parameters regardless the length of the dental bridge.

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