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Low-level laser therapy affects dentinogenesis and angiogenesis of in vitro 3D cultures of dentin-pulp complex
摘要： To investigate the effects of gallium-aluminum-arsenide (GaAlAs) diode laser low-level laser therapy (LLLT) on angiogenesis and dentinogenesis of the dentin-pulp complex in a human tooth slice-based in vitro model. Forty tooth slices were prepared from 31 human third molars. Slices were cultured at 37 °C, 5% CO2, and 95% humidity and randomly assigned to one of the following groups: group I: no laser treatment, group II: 660-nm diode laser; energy density = 1 J/cm2, group III: 660-nm diode laser; energy density = 3 J/cm2, group IV: 810-nm diode laser; energy density = 1 J/cm2 and group V: 810-nm diode laser; energy density = 3 J/cm2. LLLT was applied on the third and fifth days of culture. After 7 days, tissues were retrieved for real-time RT-PCR analysis to investigate the expression of VEGF, VEGFR2, DSPP, DMP-1, and BSP in respect to controls. Lower energy density (1 J/cm2) with the 660 nm wavelength showed a statistically significant up-regulation of both angiogenic (VEGF: 15.3-folds and VEGFR2: 3.8-folds) and odontogenic genes (DSPP: 6.1-folds, DMP-1: 3-fold, and BSP: 6.7-folds). While the higher energy density (3 J/cm2) with the 810 nm wavelength resulted in statistically significant up-regulation of odontogenic genes (DSPP: 2.5-folds, DMP-1: 17.7-folds, and BSP: 7.1-folds), however, the angiogenic genes had variable results where VEGF was up-regulated while VEGFR2 was down-regulated. Low-level laser therapy could be a useful tool to promote angiogenesis and dentinogenesis of the dentin-pulp complex when parameters are optimized.
关键词： Low-level laser therapy,Dentinogenesis,Dentin-pulp complex,Angiogenesis,Tooth slice model
更新于2025-11-25 10:30:42
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[ASME ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - San Francisco, California, USA (Monday 27 August 2018)] ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - Improved Approaches for FEA Analyses of PBGA Packages Subjected to Thermal Cycling
摘要： The study of solder joint reliability is one of the priority issues in electronic packaging. Solder alloys experience a highly nonlinear material behavior when subject to thermal cycling. It is a time consuming and difficult task to study the behavior of solder joints using experimental approaches. Finite element analysis provides a more efficient way to better understand the behavior of solder joints when accurate material models are available. With the developments of FEA algorithms and computer resources, the analysis approaches used for electronic packaging assemblies have evolved from 2-dimensional to 3-dimensional analyses, with far fewer assumptions needed in the fully 3D case. In this paper, we compare different FEA approaches covering various 2D and 3D modeling techniques to understand their advantages and drawbacks, especially as related to simulation accuracy and efficiency. Several models for a typical BGA assembly were prepared and analyzed including traditional mesh continuity models (2D slice model, 3D slice model, and 3D quarter model), as well as advanced models that employ Multi-Point Constraints (MPCs) and submodeling (global/local models). The Anand viscoplastic model was used for the solder joint material behavior in all of the FEA approaches. For the 3D mesh continuity models, an optimal analysis approach has been proposed to achieve the best balance between the accuracy of the simulation result and numerical efficiency of the simulation. Mesh transitions were used to maintain mesh continuity between regions of different mesh densities. A best choice of load step size was also found to reduce overall simulation time. For the analysis using MPCs to bond different meshes, two improved modeling strategies have been proposed including a suggested ratio of contacting elements and the use of multiple-MPC contact pairs to reduce overall mesh density of the FE model. An improved simulation strategy using submodeling has also been developed to obtain the best compromise in the global and local models between the mesh quality and load step size. An improved geometric simplification of the solder joint for use with energy based fatigue criteria was developed. Finally, comparisons and suggestions were made for the best analysis approach when using FEA techniques to predict the behavior of solder joints in PBGA packages.
关键词： 3D Model,Finite Element Analysis,PBGA,Multipoint Constraint,Submodeling,3D Slice Model,Global-Local Model,2D Slice Model
更新于2025-09-23 15:21:21