Characteristics of experimental resin-modified glass-ionomer cements, containing alternate monomers to HEMA

Effect of milled and lithography-based additively manufactured zirconia (3Y-TZP) on the biological properties of human osteoblasts

STATEMENT OF PROBLEM

Lithography-based additively manufactured (AM) zirconia has been used to fabricate dental implants and custom barriers for guided bone regeneration procedures. However, studies on the effect of AM zirconia on the biological properties of human osteoblasts are lacking.

PURPOSE

The purpose of this in vitro study was to compare the effect of milled and lithography-based AM zirconia on the biological properties of normal human osteoblasts (NHOsts), as well as to compare the chemical composition between the milled and lithography-based AM 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) zirconia.

MATERIAL AND METHODS

Three mol percentage yttria-stabilized tetragonal zirconia polycrystal disks (Ø6×2-mm) were fabricated using subtractive milling (Priti multidisc ZrO2 monochrome) (M group) and lithography-based additive manufacturing methods (LithaCon 3Y 210) (AM group) (n=10). NHOsts were exposed to different material extracts (1:1, 1:2, and 1:4) and cytotoxicity, cell migration, cell morphology, and cell attachment biological tests were completed. Additionally, for morphological and chemical analysis, a scanning electronic microscopy with energy-dispersive X-ray analysis (SEM/EDX) evaluation was completed. Data were analyzed by using 1-way ANOVA and the Dunnett test (α=.05).

RESULTS

Substantial cell attachment and spreading were observed in both material surfaces. The presence of zirconium was evident in both groups, although the percentage of zirconium in the AM group (64.7%) was slightly higher than in the M group (52.6%). When NHOsts were cultured in the presence of the different material eluates, the M and AM groups exhibited similar NHOst viability and migration rates when compared with untreated cells; no significant differences were found (P>.05).

CONCLUSIONS

The lithography-based AM zirconia tested showed adequate cytocompatibility without differences when compared with the milled zirconia (M group) specimens. Slight chemical element composition differences were found between milled and lithography-based AM zirconia.

Assessment of physical/mechanical properties and cytotoxicity of dual-cured resin cements containing Sr-bioactive glass nanoparticles and calcium phosphate

The aim was to develop dual-cured resin cements containing Sr-bioactive glass nanoparticles (Sr-BGNPs; 5 or 10 wt%) and monocalcium phosphate monohydrate (MCPM; 3 or 6 wt%). Effects of additives on degree of monomer conversion (DC), biaxial flexural strength/modulus, shear bond strength (SBS), mass/volume change, color stability, ion release, and cytotoxicity were examined. Controls included material without reactive fillers and Panavia SA Plus (PV). Experimental cements showed higher DC than PV regardless of light activation (p<0.05). Mean SBS and color stability were comparable between experimental cements and PV. Cell viability upon the exposure to sample extracts of experimental cements was 80%-92%. High additive concentrations led to lower strength and modulus than PV (p<0.05). The additives increased mass change, reduced color stability, and promoted ion release. The experimental resin cements demonstrated acceptable mechanical/chemical properties and cytotoxicity. The additives reduced the strength but provided ion release, a desirable action to prevent recurrent caries.

The In-Vitro Effect of Silver and Zinc Oxide Nanoparticles on Fluoride Release and Microhardness of a Resin-Modified Glass Ionomer Cement

Reinforcement of nanoparticles into existing restorative biomaterials in dentistry is an area of interest. The aim of the current investigation was to incorporate silver nanoparticles (SNP) and zinc oxide nanoparticles (ZnONP) into a commercially available resin-modified glass ionomer cement (RMGIC). Their effects on the fluoride (F-) release from RMGIC were also investigated over a period of 14-days. Nanoparticles were incorporated at a loading concentration of 5 wt%, either individually or in a combination of both. Scanning electron microscopy (SEM), Fourier Transform infrared spectroscopy (FTIR), Nanocomputerized tomography (NanoCT), and the Vickers microhardness tester were used to examine the specimens. The fluoride release was analyzed by high performance liquid chromatography (HPLC). Data were analysed using ANOVA and Tukey’s test. RMGIC containing 5% ZnONP and 5% SNP + 5% ZnONP showed significant alterations in the surface ultrastructure with pores being evident in the surface. Fluoride release in parts per million (ppm) was highest in the 5% SNP and 5% ZnO-NP incorporated RMGIC compared to the control group and 5% SNP-incorporated RMGIC. RMGIC, as well as change in color observed in the 5% SNP incorporated RMGIC.