Showing papers by "Fabrício Mezzomo Collares published in 2023"

Experimental Composite Resin with Myristyltrimethylammonium Bromide (MYTAB) and Alpha-Tricalcium Phosphate (α-TCP): Antibacterial and Remineralizing Effect

Abstract: The aim of this study was to develop an experimental composite resin with the addition of myristyltrimethylammonium bromide (MYTAB) and α -tricalcium phosphate (α-TCP) as an antibacterial and remineralizing material. Experimental composite resins composed of 75 wt% Bisphenol A-Glycidyl Methacrylate (BisGMA) and 25 wt% Triethylene Glycol Dimethacrylate (TEGDMA) were produced. Some 1 mol% Trimethyl benzoyl-diphenylphosphine oxide (TPO) was used as a photoinitiator, and butylated hydroxytoluene (BTH) was added as a polymerization inhibitor. Silica (1.5 wt%) and barium glass (65 wt%) particles were added as inorganic fillers. For remineralizing and antibacterial effect, α-TCP (10 wt%) and MYTAB (5 wt%) were incorporated into the resin matrix (α-TCP/MYTAB group). A group without the addition of α-TCP/MYTAB was used as a control. Resins were evaluated for their degree of conversion (n = 3) by Fourier Transform Infrared Spectroscopy (FTIR). The flexural strength (n = 5) was assessed based on ISO 4049:2019 requirements. Microhardness was assessed to calculate softening in solvent (n = 3) after ethanol immersion. The mineral deposition (n = 3) was evaluated after immersion in SBF, while cytotoxicity was tested with HaCaT cells (n = 5). Antimicrobial activity (n = 3) was analyzed against S. mutans. The degree of conversion was not influenced by the antibacterial and remineralizing compounds, and all groups reached values > 60%. The α-TCP/MYTAB addition promoted increased softening of polymers after immersion in ethanol and reduced their flexural strength and the viability of cells in vitro. A reduction in S. mutans viability was observed for the α-TCP/MYTAB group in biofilm formation and planktonic bacteria, with an antibacterial effect > 3log10 for the developed materials. Higher intensity of phosphate compounds on the sample’s surface was detected in the α-TCP/MYTAB group. The addition of α-TCP and MYTAB promoted remineralizing and antibacterial effects on the developed resins and may be a strategy for bioactive composites.

Biomechanical behavior of a 3D-printed denture base material.

Abstract: PURPOSE To evaluate relevant material properties (flexural strength (σf), elastic modulus (E), water sorption (Wsp) and solubility (Wsl), and biocompatibility) of a 3D-printed resin (3D) and a heat cured acrylic resin (AR-control) used for complete denture manufacturing, testing the hypothesis that constructs from both materials would present acceptable material properties for clinical use. MATERIALS AND METHODS The σf, E, Wsp and Wsl were evaluated according to the ISO 20795-1:2013 standard, and the biocompatibility was evaluated using 3-4,5-dimethyl-thiazol-2-yl-2.5-diphenyltetrazolium bromide (MTT) and sulforhodamine B (SRB) assays. Disk-shaped specimens were fabricated and used for Wsp (n = 5), Wsl (n = 5), and biocompatibility (n = 3). Bar-shaped specimens (n = 30) were fabricated and stored in 37⁰ C distilled water for 48 hours and 6 months before flexural testing in a universal testing machine with constant displacement rate (5 ± 1 mm/min) until fracture. Data from σf, E, Wsp, Wsl and biocompatibility were statistically analyzed using Student t test (α= 0.05), Weibull analysis was also used for σf and E data. RESULTS Significant differences between the two polymers were found for the evaluated material properties. Water storage for 6 months did not affect the flexural strength of 3D. Yet, the additive manufactured polymer showed inadequate flexural strength and water solubility values. CONCLUSION Despite adequate biocompatibility and strength stability after 6 months of water storage, the additive manufactured polymer recommended for complete denture needs further development to improve the remaining material properties evaluated in this study.

Niobium-containing bioactive glasses modulate alkaline phosphatase activity during bone repair.

Abstract: This study aimed to evaluate the pre-clinical behavior of niobium-containing bioactive glasses (BAGNb) by their ability to promote bone repair and regulate alkaline phosphatase (ALP) levels in an animal model. BAGNbs were produced as powders and as scaffolds and surgically implanted in the femur of male rats (Wistar lineage n = 10). Glasses without Nb (BAG) were produced and implanted as well. The Autogenous Bone (AB) was used as a control. After 15, 30, and 60 days of surgical implantation, blood serum samples were collected to quantify ALP activity, and femurs were removed to assess bone repair. Bone samples were histologically processed and stained with H&E to quantify the % new bone into defects. No postoperative complications were identified. Early-stage repair (15 days) resulted in increased ALP activity for all groups, with increased values ​​for powdered BAGNb. The maturation of the new bone led to a reduction in serum ALP levels. Histological sections showed the formation of immature bone tissue and vascularization with the progression of bone deposition to mature and functional tissue over time. BAG powder showed less new bone formation in 15 days, while the analysis at 30 and 60 days showed no difference between groups (p > .05). Niobium-containing bioactive glasses safely and successfully induced bone repair in vivo. The modulation of ALP activity may be a pathway to describe the ability of niobium-containing materials to contribute to new bone formation.