Apatite formation on dental ceramics modified by a bioactive glass

Effect of Manipulation Methods and Storage Environments on the Microstructural, Chemical, and Mechanical Properties of Calcium-Enriched Mixture Cement

This study aimed to evaluate the impact of different manipulation methods and storage environments on the microstructural, chemical, and mechanical properties of calcium-enriched mixture (CEM) cement. Four sample groups were examined, including nondried (ND-I) and dried (D-I) groups placed directly in an incubator, dried samples stored in phosphate-buffered saline (PBS) (D-P), and dried samples stored in distilled water (D-W). Various analyses, including Vickers microhardness, compressive strength, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) were conducted after incubating the samples for 7 days. The data were analyzed by Shapiro-Wilk, Levene, independent t, one-way ANOVA, and Tukey HSD tests. Key findings include the ND-I group exhibited a significantly longer setting time but the lowest microhardness and compressive strength. D-P showed the highest microhardness, while D-W displayed the highest compressive strength. FTIR analysis revealed vibration modes related to (PO4)3- ions and Si compounds in all groups, with dried groups showing more vibrations of (PO4)3- ions and OH groups, and D-P and D-W groups displayed vibration modes of (CO3)2- ions. XRD analysis indicated increased tri/dicalcium silicate reflections in CEM groups exposed to PBS or distilled water. D-I and D-W groups presented hexagonal or rectangular cubic and needle-like crystals, while D-P showed a homogeneous globular structure covered with fine crystals. The order of the weight percentage of major elemental constituents of D-P group was oxygen, calcium, phosphorus, zirconium, barium, carbon, silicon, and sulfur. Incremental placement, drying each increment, and exposing CEM to PBS/tissue fluids result in a faster set and more tolerant cement with a more uniform microstructure. The formation of hydroxyapatite can occur on the surface of the set cement.

Evaluation of the micro-mechanical and bioactive properties of bioactive glass-dental porcelain composite

The aim of this study was to evaluate microhardness and elastic modulus of a novel sol-gel derived dental ceramic - 58S bioactive glass composite (BP67: Bioactive Glass:33.3%, Dental Ceramic:66.7%) BP67¹ material by micro-indentation and to investigate its microstructure and bioactivity. The research hypotheses were that the values of microhardness (1) and elastic modulus (2) of the novel bioceramic composite and the commercial dental ceramic will be of the same order. The experimental sol-gel derived ceramics showed similar microstructural characteristics to a commercial feldspathic porcelain, and presence of additional calcium phosphate phases, which contributed its bioactivity. The formation of an apatite-like layer on the materials' surface observed by Fourier Transform Infrared (FTIR)² spectroscopy, X-ray Diffraction (XRD)³ and Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS)⁴ techniques after 12 days of maintenance in Conventional Simulated Body Fluid (cSBF)⁵ solution. The BP67 exhibited values of microhardness and modulus of elasticity which were not statistically significant different compared to dental ceramic, indicating the adequate mechanical integrity of the material. The results of this study suggest that the novel bioactive composite could be potentially applied in prosthetic dentistry, while its thermal and optical properties should be investigated in future studies.

Attachment and proliferation of human periodontal ligament fibroblasts on bioactive glass modified ceramics

In this study, six groups of modified ceramic specimens were constructed and were studied comparatively with dental porcelain (P:control) for their ability to support human periodontal ligament fibroblasts attachment and proliferation. The dental porcelain was initially coated with bioactive glass (PCB) or with a mixture of porcelain and bioactive glass (PCBP) and then calcium-phosphate rich (Ca-P) or hydroxy-carbonate apatite (HCAp) layers were bio-mimetically developed on both surfaces (PCB and PCBP) after immersion in simulated body fluid. The development and characterization of Ca-P and HCAp layers on PCBCa-P, PCBHCAp, PCBPCa-P, PCBPHCAp specimens' surfaces were evaluated by Scanning Electron Microscopy (SEM) and further confirmed by Fourier Transform Infrared Spectroscopy (FTIR). The modified ceramics differed from their controls concerning their surface morphology as evaluated by SEM, and their surface chemical composition (Al, P, Si, Ca, Na and K) as evaluated by Energy Dispersive Spectroscopy (EDS). Almost all modified specimens supported cell attachment, spreading and proliferation at higher extent than the control porcelain specimens. The additional layers of Ca-P or HCAp on PCBP and PCB specimens were found to positively affect cell attachment and proliferation. The highest cell population, of all specimens tested, was observed on PCBPCa-P and PCBPHCAp. The Ca-P particles present on all Ca-P and HCAp coated specimens seemed to be involved in cell adhesion.

Attachment and Proliferation of Human Periodontal Ligament Fibroblasts on Fibronectin-Coated Bioactive Glass Modified Ceramics

The effect of fibronectin (FN) on human periodontal ligament fibroblasts (PDLF) attachment and proliferation on Bioglass® (PerioGlas® Synthetic Bone Graft Particulate, US Biomaterials) modified dental ceramics, was investigated in vitro. FN introduced limited alterations in cell attachment on Bioglass®-modified dental ceramics in comparison with the corresponding non-FN-coated specimens but had a profound positive effect on Bioglass®-coated specimens that weakly supported both cell attachment and proliferation. The amount of protein adsorbed on the specimens was not proportional to its biological activity, i.e. cell attachment, spread and proliferation, probably due to surface energy variations and FN conformational changes induced by differences in surface composition and morphology of the different dental ceramics modifications.

Compound changes and tooth mineralization effects of glass ionomer cements containing bioactive glass (S53P4), an in vivo study

In this study, modifications of glass ionomer cements (GICs) were made by adding bioactive glass (BAG) to GIC to obtain bioactive restorative materials. This study used SEM, EDS and visual analysis to examine the bioactivity and the ability of the study materials to mineralize dentin. Conventional cure and resin-modified light-curing GIC were used. The materials consisted of powder and liquid. Three experimental materials were made by mixing 10-30 wt% of BAG powder with GIC powders. Commercially available GIC without BAG were used as controls. Class III restorations were made in altogether 62 intact beagle dog teeth, and the operation was performed under general anesthesia. The restorations were followed clinically for 1, 3 or 6 weeks. Resin-modified GIC containing BAG showed uniform CaP surface formation on the restorations. Mineral depositions in the close vicinity of the restoration-dentin interface and in deeper parts of dentin tubules were also noticed in resin-modified GIC containing BAG particles. It can be concluded that resin-modified GIC containing BAG have good potential in clinical applications where enhanced mineralization is expected.