Probing the micro- and nanoscopic properties of dental materials using infrared spectroscopy: A proof-of-principle study

Molecular dynamic studies of gold nanoparticles in a dental material TEGDMA

CONTEXT

In the context of biomaterials, triethylene glycol dimethacrylate (TEGDMA) is a widely used monomer in dental resins due to its favorable mechanical properties and ease of polymerization. However, improving its structural stability and enhancing its performance in biological applications remain crucial goals. This study examines the impact of incorporating gold (Au) nanoparticles into the TEGDMA matrix, focusing on their potential to improve mechanical, thermal, and optical properties for biomedical applications. Gold is known for its bio-compatibility, antimicrobial properties, and ability to improve material conductivity, making it an attractive addition for dental and tissue engineering composites. By introducing Au nanoparticles at varying concentrations (0%, 3%, 4%, and 5%), this research aims to optimize TEGDMA's performance in medical grade materials, particularly in dental composites where enhanced strength and durability are vital.

METHODS

Molecular dynamics (MD) simulations were employed to investigate the structural, thermal, and mechanical properties of TEGDMA with varying concentrations of Au nanoparticles. LAMMPS software was used to compute cohesive energy, surface tension, viscosity, and mechanical moduli. Quantum chemical calculations were conducted using Gaussian and RDKit to optimize the molecular structure and obtain electronic properties, including UV-Vis and IR spectra. Phonon spectra and lattice energy were analyzed to evaluate the vibrational properties and thermal stability of the Au-doped TEGDMA matrix. The results were benchmarked against experimental data, offering a comprehensive computational analysis of the impact of Au nanoparticles on the material's performance. Functional data analysis techniques were applied to correlate nanoparticle concentration with the computed properties.

Iron and Magnesium Co-substituted Hydroxyapatite Nanoparticles in Orthodontic Composite: A Preliminary Assessment

Aim The study aims to characterize Fe and Mg co-substituted hydroxyapatite nanoparticles (FeMgHAPn) and assess the antimicrobial properties of FeMgHAPn-incorporated orthodontic composite. Materials and methods FeMgHAPn was synthesized using the sol-gel method, and the prepared nanoparticle powder was characterized using Fourier Transform Infrared Spectroscopy (FTIR), energy-dispersive X-ray analysis (EDX)) and scanning electron microscopic (SEM) analysis. The FeMgHAPn was incorporated into a commercially available orthodontic composite in two concentrations (40 and 20 μL), and the structure was examined using SEM. The FeMgHAPn-incorporated composite was tested for its antimicrobial efficacy against Streptococcus mutans, Staphylococcus aureus, and Escherichia coli using the agar-well diffusion method. The zones of inhibition (ZOI) were measured in millimeters (mm). Results The characterization of the FeMgHAPn indicated the successful formation of the nanoparticle without any impurities or byproducts. The high concentration (40 μL) of FeMgHAPn-incorporated orthodontic composite showed the maximum ZOI against all three microbes, followed by the low concentration (20 μL) and the control group. Conclusion The FeMgHAPn-incorporated orthodontic composite showed promising antimicrobial activity against caries-causing S. mutans, S. aureus, and E. coli.

Universality of random-site percolation thresholds for two-dimensional complex noncompact neighborhoods

The phenomenon of percolation is one of the core topics in statistical mechanics. It allows one to study the phase transition known in real physical systems only in a purely geometrical way. In this paper, we determine thresholds p_{c} for random-site percolation in triangular and honeycomb lattices for all available neighborhoods containing sites from the sixth coordination zone. The results obtained (together with the percolation thresholds gathered from the literature also for other complex neighborhoods and also for a square lattice) show the power-law dependence p_{c}∝(ζ/K)^{-γ} with γ=0.526(11), 0.5439(63), and 0.5932(47), for a honeycomb, square, and triangular lattice, respectively, and p_{c}∝ζ^{-γ} with γ=0.5546(67) independently on the underlying lattice. The index ζ=∑_{i}z_{i}r_{i} stands for an average coordination number weighted by distance, that is, depending on the coordination zone number i, the neighborhood coordination number z_{i}, and the distance r_{i} to sites in the ith coordination zone from the central site. The number K indicates lattice connectivity, that is, K=3, 4, and 6 for the honeycomb, square, and triangular lattice, respectively.