IADR Abstract Archives
Cuspal Movement Evaluation of Class II Composite Restoration Using DIC And FEA
Objectives: Clinically, cuspal movement is positively correlated with polymerization shrinkage stress. The aim of this study is to examine the use of Digital Image Correlation and Finite Element Analisys to evaluate cuspal movement of model Class-II composite-resin restorations.
Methods: A commercial dental composite resin with linear shrinkage strain of 0.8% was used to restore 5 model Class-II mesio-occlusal-distal cavities (8-mm long, 4-mm wide and 4-mm deep) in aluminum blocks (8-mm thick, 10-mm wide and 14-mm tall). One of the proximal surfaces was flattened using a piece of hard cardboard paper and sprayed with a thin layer of carbon powder to produce speckles for deformation tracking. An image of the speckled proximal surface facing the camera was taken before curing. The restoration was then cured for 100s using a curing light (Elipar Freelight, 3M ESPE, St. Paul, MN, USA) with an intensity of 1200 mW/cm2, and 10 minutes later a second image was taken. Surface displacements were obtained by analyzing the images using DIC software (7.2 DaVis, LaVision Inc.). The experimental results were compared with finite element analysis (FEA). The aluminum model tooth with a Class-II restoration was simulated using Abaqus (SIMULIA, Dassault Systèmes, Providence, RI, USA). The base of the block was fully constrained. Loading was applied through temperature changes in the composite resin. A pseudo coefficient of thermal expansion (α) of the composite resin was introduced to simulate polymerization shrinkage such that Δε_s=αΔT.
Results: The experimental data agreed well with FEA prediction (Fig. 1). Cuspal displacements were 32.6 ± 3.8 μm and 29.8 μm, respectively, from DIC and FEA. FE-predicted results showed that in Class-II restorations there is high strain distribution at the top surface and high stress distribution at the floor.
Conclusions: Digital Image Correlation was successfully employed for the validation of FEA in measuring cuspal movement in model Class II composite resin restorations.
Methods: A commercial dental composite resin with linear shrinkage strain of 0.8% was used to restore 5 model Class-II mesio-occlusal-distal cavities (8-mm long, 4-mm wide and 4-mm deep) in aluminum blocks (8-mm thick, 10-mm wide and 14-mm tall). One of the proximal surfaces was flattened using a piece of hard cardboard paper and sprayed with a thin layer of carbon powder to produce speckles for deformation tracking. An image of the speckled proximal surface facing the camera was taken before curing. The restoration was then cured for 100s using a curing light (Elipar Freelight, 3M ESPE, St. Paul, MN, USA) with an intensity of 1200 mW/cm2, and 10 minutes later a second image was taken. Surface displacements were obtained by analyzing the images using DIC software (7.2 DaVis, LaVision Inc.). The experimental results were compared with finite element analysis (FEA). The aluminum model tooth with a Class-II restoration was simulated using Abaqus (SIMULIA, Dassault Systèmes, Providence, RI, USA). The base of the block was fully constrained. Loading was applied through temperature changes in the composite resin. A pseudo coefficient of thermal expansion (α) of the composite resin was introduced to simulate polymerization shrinkage such that Δε_s=αΔT.
Results: The experimental data agreed well with FEA prediction (Fig. 1). Cuspal displacements were 32.6 ± 3.8 μm and 29.8 μm, respectively, from DIC and FEA. FE-predicted results showed that in Class-II restorations there is high strain distribution at the top surface and high stress distribution at the floor.
Conclusions: Digital Image Correlation was successfully employed for the validation of FEA in measuring cuspal movement in model Class II composite resin restorations.
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