Study Biocompatibility and Osteogenic Differentiation Potential of Human Umbilical Cord Mesenchymal Stem Cells (hUCMSCs) with Gelatin Solvent

The human umbilical cord is a source of numerous Mesenchymal Stem Cells (MSCs), making it as a potential source of allogeneic multipotent cell for bone tissue engineering. The aims of this study were to find: 1) Human Umbilical Cord Mesenchymal Stem Cells (hUCMSCs) phenotypic characterization, 2) The in-vitro osteogenic differentiation potential of hUCMSCs, 3) The cytotoxicity of gelatin solvent to hUCMSCs using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay. As a result, through characterization of hUCMSCs, the majority of target cells expressed specific MSCs markers, Cellular Differentiation (CD)73, smaller number of subpopulation expressed CD90 with only minimal subpopulation expressed CD105 and all negative MSCs markers. Osteoblastic differentiation was found in a significantly high number of cells when in vitro osteogenic differentiation of hUCMSCs with Alizarin Red staining was done. Biocompatibility analysis using the MTT assay showed that gelatin solvent and Alpha modification of minimum essential medium Eagle (α-MEM) was non-toxic for hUCMSCs in vitro. The study concluded that hUCMSCs isolated from human umbilical cord was capable of undergoing in vitro osteogenesis, indicating its potential as allogeneic stem cells for clinical application in bone tissue engineering.

Biomechanical Analysis of Implant Assisted-Overdentures with Variations in the Attachments Systems

The aim of this study was to assess the stress patterns on the peri-implant zone and residual alveolar ridge in different overdenture attachment system designs by the photoelasticity method. Four attachments systems were tested: O-ring, ERA, Bar-clip, and Bar-clip/O-ring association. The prostheses were loaded with 100 N in five pre-determined points and the photoelastic model was evaluated by a circular polariscope. The anterior load, O-ring, and ERA showed better stress distribution in relation to the bars systems, which presented stress levels surrounding implants. The molar load, Bar-clip/O-ring association, presented the biggest stress concentration on the peri-implant region in relation to the others. When the second molar was loaded, there was a concentration of stress in the alveolar ridge in all situations analyzed. Within the limitation of this “in vitro” study, it could be concluded that there were biomechanical differences among the attachments systems analyzed, principally between isolated and the bars systems. The O-ring showed better stress distribution and the Bar-clip/O-ring showed higher stress concentration.

A General Strategy for Efficiently Constructing Multifunctional Cluster Fillers Using a Three-Fluid Nozzle Spray Drying Technique for Dental Restoration

Multifunctional fillers are greatly required for dental resin composites(DRCs).In this work,a spray dryer with a three-fluid nozzle was applied for the first time to construct high-performance complex nanoparticle clusters(CNCs)consisting of different functional nanofillers for dental restoration.The application of a three-fluid nozzle can effectively avoid the aggregation of different nanoparticles with opposite zeta potentials before the spray drying process in order to construct regularly shaped CNCs.For a SiO_(2)–ZrO_(2) binary system,the SiO_(2)–ZrO_(2) CNCs constructed using a three-fluid nozzle maintained their excellent mechanical properties((133.3±4.7)MPa,(8.8±0.5)GPa,(371.1±13.3)MPa,and(64.5±0.7)HV for flexural strength,flexural modulus,compressive strength,and hardness of DRCs,respectively),despite the introduction of ZrO_(2) nanoparticles,whereas their counterparts constructed using a two-fluid nozzle showed significantly decreased mechanical properties.Furthermore,heat treatment of the SiO_(2)-ZrO_(2) CNCs significantly improved the mechanical properties and radiopacity of the DRCs.The DRCs containing over 10%mass fraction ZrO_(2) nanoparticles can meet the requirement for radiopaque fillers.More importantly,this method can be expanded to ternary or quaternary systems.DRCs filled with SiO_(2)-ZrO_(2)-ZnO CNCs with a ratio of 56:10:4 displayed high antibacterial activity(antibacterial ratio>99%)in addition to excellent mechanical properties and radiopacity.Thus,the three-fluid nozzle spray drying technique holds great potential for the efficient construction of multifunctional cluster fillers for DRCs.

Titanium membrane layered between fluvastatin-loaded poly(lactic-co-glycolic)acid for guided bone regeneration

The aimof this study was to investigate titaniummembranes(TMs)layered between poly(lactic-co-glycolic acid)(PLGA)containing fluvastatin(FS)for use in guided bone regeneration.Membranes consisting of PLGA,FS-containing PLGA(PLGA–FS),TM layered between PLGA(TM–PLGA)and TM layered between FS-containing PLGA(TM–PLGA–FS)were prepared,and their mechanical and chemical properties were evaluated.The TM groups showed statistically significant differences,in terms of tensile strength and elastic modulus,when compared to the PLGA groups.The release of FS was demonstrated to be higher in the TM–PLGA–FS group than the PLGA–FS group after Day 14.The effect of membrane implantation on the calvaria of Wistar rats was measured using micro-computed tomography(micro-CT)and morphometrical analyses,as well as histological observations.At 4weeks,the TM–PLGA–FS and TM–PLGA groups were found to have lower bone mineral density but higher bone formation,when compared to the control and PLGA groups.At 8weeks,the use of TM–PLGA–FS membranes significantly enhanced bone formation in the calvaria model,compared to the other groups.These results suggest that a TM layered between PLGA containing FS potentially enhances bone formation,thus showing good potential as a GBR membrane.