Drug Delivery Systems for Dental Applications

Grafted Microparticles Based on Glycidyl Methacrylate, Hydroxyethyl Methacrylate and Sodium Hyaluronate: Synthesis, Characterization, Adsorption and Release Studies of Metronidazole

Three types of precursor microparticles based on glycidyl methacrylate, hydroxyethyl methacrylate and one of the following three crosslinking agents (mono-, di- or triethylene glycol dimethacrylate) were prepared using the suspension polymerization technique. The precursor microparticles were subsequently used to obtain three types of hybrid microparticles. Their synthesis took place by grafting sodium hyaluronate, in a basic medium, to the epoxy groups located on the surface of the precursor microparticles. Both types of the microparticles were characterized by: FTIR spectroscopy, epoxy groups content, thermogravimetric analysis, dimensional analysis, grafting degree of sodium hyaluronate, SEM and AFM analyses, and specific parameters of porous structures (specific surface area, pore volume, porosity). The results showed that the hybrid microparticles present higher specific surface areas, higher swelling capacities as well as higher adsorption capacities of antimicrobial drugs (metronidazole). To examine the interactions between metronidazole and the precursor/hybrid microparticles the adsorption equilibrium, kinetic and thermodynamic studies were carried out. Thus, it was determined the performance of the polymer systems in order to select a polymer-drug system with a high efficiency. The release kinetics reflect that the release mechanism of metronidazole in the case of hybrid microparticles is a complex mechanism characteristic of anomalous or non-Fickian diffusion.

Diatomaceous earth as a drug-loaded carrier in a glass-ionomer cement

The effect of a natural filler (diatomaceous earth [DE], a promising drug-delivery agent) and its content was investigated on the performance of a model glass-ionomer cement (GIC). Three sample series, differing in DE content (0, 2.5 and 5 wt%), were prepared using a commercial GIC as a matrix (3M Ketac Molar Easymix). The resultant surface microhardness and roughness, wear performance, and compressive strength of the samples were measured after the samples had been stored in deionized water at 37°C for a fixed time. Moreover, the film thickness was tested for the freshly mixed samples. The numerical data was subjected to statistical analysis, in order to test the null hypotheses of the equality of the measured properties between the reference and the DE-modified samples. According to the results, diatomaceous earth particles are uniformly distributed in the GIC matrix, and the cavities of frustules tend to be filled with the GIC. This translates into the observed performance of the DE-loaded GIC. Compared with the reference material (0 wt% DE), the surface microhardness (2.5 wt% DE, p = 0.014; 5 wt% DE, p = 0.005) and roughness (e.g. Ra; 2.5 wt% DE, p = 0.003; 5 wt% DE, p < 0.001) are increased. No effect on the wear performance (p = 0.530 and 0.256, respectively) or compressive strength (p = 0.514) was noticed in the case of DE partially substituting the glass phase. Based on the study results, it is evidenced that diatom frustules are a suitable filler for application in conventional glass-ionomer cements as the glass-substituting drug-loaded carrier. Notably, however, the surface finish method of the DE-filled materials needs development.

The Benefits of Smart Nanoparticles in Dental Applications

Dentistry, as a branch of medicine, has undergone continuous evolution over time. The scientific world has focused its attention on the development of new methods and materials with improved properties that meet the needs of patients. For this purpose, the replacement of so-called "passive" dental materials that do not interact with the oral environment with "smart/intelligent" materials that have the capability to change their shape, color, or size in response to an externally stimulus, such as the temperature, pH, light, moisture, stress, electric or magnetic fields, and chemical compounds, has received much attention in recent years. A strong trend in dental applications is to apply nanotechnology and smart nanomaterials such as nanoclays, nanofibers, nanocomposites, nanobubbles, nanocapsules, solid-lipid nanoparticles, nanospheres, metallic nanoparticles, nanotubes, and nanocrystals. Among the nanomaterials, the smart nanoparticles present several advantages compared to other materials, creating the possibility to use them in various dental applications, including preventive dentistry, endodontics, restoration, and periodontal diseases. This review is focused on the recent developments and dental applications (drug delivery systems and restoration materials) of smart nanoparticles.

Molecular dynamics studies of polysaccharide carrier based on starch in dental cavities

Health is an important element that influences the level of development in a community. Studies show that tooth decay has been prevalent recently. Starch incorporating curcumin can serve as an alternative approach in preventing the activity of Streptococcus mutans attributed to biofilm and plaque formation on teeth. In this research, the performance of starch nanoparticle as a carrier for curcumin, a natural anti-inflammatory and a strong antioxidant agent, in decreasing dental caries was simulated. In the first stage, the conformational rearrangements of molecules and their interactions with other molecular species in a range of environments were examined via computational techniques and molecular dynamics (MD) simulation. The charts of energy, temperature, density, cell size and the radial distribution function (RDF) derived from the simulation, confirmed that during 5 initial steps there was a stable binding between the curcumin and starch in the presence of bacteria. The energy released in the starch formed nanosphere is very high, and this indicates a full reaction in the system. However, the density-decreasing trend of nanosystem suggests that it can effectively inhibit the activity of microorganism.

Curcumin-loaded chitosan/carboxymethyl starch/montmorillonite bio-nanocomposite for reduction of dental bacterial biofilm formation

A novel bio nanocomposite of Carboxymethyl Starch (CMS)-Chitosan (CS)-Montmorillonite (MMT) was developed for Curcumin delivery. To improve Curcumin entrapment into Cs-CMS-MMT, different ratios of Chitosan (Cs), Carboxymethyl Starch (CMS) and MMT were used. Particle size and Curcumin entrapment efficiency (EE) were highly affected by different formulation variables. Polysaccharide concentration, Cs-CMS ratio and sonication time had significant effect on particle size. MMT addition enhanced the entrapment efficiency. To optimize entrapment efficiency of Curcumin, statistical analysis was used, and an experiment based on screening design performed with two variants. Morphology and structural characterization of nanocomposite and Curcumin entrapment efficiency were analyzed. The optimal formulation had the average particles size of 35.9nm with Curcumin entrapment efficiency of 91%. Finally, the antibacterial activity of bio nanocomposite against Streptococcus mutans was assessed. Curcumin-loaded bio nanocomposite hindered the formation of biofilm on dental models very effectively.