MATERIALS AND METHODS: Three-dimensional solid models of the maxilla, mucosa, and denture of a selected edentulous patient were created using Mimics and CATIA software. The FEA model was created and duplicated in ANSYS 16.0 to perform two simulations for the IOD and the CD models. The values of maximum stress and strain and total deformation were obtained and compared to the outcomes of premaxilla resorption from a parallel clinical study.
RESULTS: The maximum principal stress in the premaxilla in the IOD model ranged from 0.019 to 0.336 MPa, while it ranged from 0.011 to 0.193 MPa in the CD model. The maximum principal strain in the IOD model was 1.75 times greater than that in the CD model. Total deformation was 1.8 times higher in the IOD model. Greater bone resorption was observed in regions of higher stress, which were on the occlusal and buccal sides of the premaxilla residual ridge.
CONCLUSION: Stress, strain, and total deformation values present in the premaxilla area beneath a CD were approximately two times greater in a comparison between an opposing mandibular two-IOD and an opposing mandibular CD. The results were consistent with a parallel clinical study in which the rate of premaxilla bone resorption was almost three times greater in the IOD group.
PURPOSE: The purpose of this laboratory and finite element analysis study was to investigate the effects on the formation of a hybrid layer of an experimental silane coupling agent containing primer solutions composed of different percentages of hydroxyethyl methacrylate.
MATERIAL AND METHODS: A total of 125 sound human premolars were restored in vitro. Simple class I cavities were formed on each tooth, followed by the application of different compositions of experimental silane primers (0%, 5%, 25%, and 50% of hydroxyethyl methacrylate), bonding agents, and dental composite resins. Bond strength tests and scanning electron microscopy analyses were performed. The laboratory experimental results were validated with finite element analysis to determine the pattern of stress distribution. Simulations were conducted by placing the restorative composite resin in a premolar tooth by imitating simple class I cavities. The laboratory and finite element analysis data were significantly different from each other, as determined by 1-way ANOVA. A post hoc analysis was conducted on the bond strength data to further clarify the effects of silane primers.
RESULTS: The strongest bond of hybrid layer (16.96 MPa) was found in the primer with 25% hydroxyethyl methacrylate, suggesting a barely visible hybrid layer barrier. The control specimens without the application of the primer and the primer specimens with no hydroxyethyl methacrylate exhibited the lowest strength values (8.30 MPa and 11.78 MPa) with intermittent and low visibility of the hybrid layer. These results were supported by finite element analysis that suggested an evenly distributed stress on the model with 25% hydroxyethyl methacrylate.
CONCLUSIONS: Different compositions of experimental silane primers affected the formation of the hybrid layer and its resulting bond strength.