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.

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Starting from glycidyl methacrylate, three dimethacrylic monomers (mono, di and triethylene glycol dimethacrylate) and chitosan, various types of porous microparticles were obtained by suspension polymerization technique. Also, using the same technique the un‐grafted porous microparticles were obtained by reaction between glycidyl methacrylate and dimethacrylic monomers. The successful grafting reaction of chitosan onto synthetic polymer networks was highlighted by FTIR spectroscopy, scanning electron microscopy, atomic force microscopy and thermogravimetric analysis. The dimensional analysis of all type of microparticles was performed by laser diffraction while the specific surface areas were determined by means of dynamic vapor sorption. Grafting of polysaccharide onto crosslinked networks has led to the preparation of polymeric materials with high specific surface area (50‐160 m2/g) and better swelling capacities (101‐106%) compared to microparticles based on glycidyl methacrylate and dimethacrylic monomers [(31‐69 m2/g) and (39‐57%), respectively]. Furthermore, the sorption properties of grafted and un‐grafted microparticles were tested using Cu(II) solution. The highest retention capacity value of Cu(II) (41.7 mg/g) was obtained when the C1 microparticles were used in the adsorption studies.

The ability of the immunosuppressant agent 6-((1-methyl-4-nitro-1H-imidazol-5-yl)thio)-9H-purine (AZA) to form pseudopolymorphs was investigated by applying conventional solid-state screening methods on 57 solvent systems. Based on the solubility data and physicochemical properties of AZA, a comprehensive polymorph screen was designed using both kinetic and thermodynamic controlled experiments. Moreover, the solubility data output of AZA in N,N-Dimethylacetamide (DMA), N-Methyl-2-pyrrolidone (NMP), N,N-Dimethylformamide (DMF), and Dimethyl sulfoxide (DMSO) caught our attention, indicating values higher than majority of tested solvents and solvent systems. Single-crystal X-ray diffraction revealed four isostructural pseudopolymorphs with DMA, NMP, DMF, and DMSO, as expected. The thermodynamics of reproducible forms were further investigated by TG/DSC analysis, establishing transitions and relations between pseudopolymorphic species. Structural features of novel pseudopolymorphs were compared and presented by Hirshfeld surfaces and associated two-dimensional fingerprint plots, according to their molecular packing in the asymmetric unit-cell.

Two types of porous microparticles based on glycidyl methacrylate, dimethacrylic monomers (ethylene glycol dimethacrylate, diethylene glycol dimethacrylate and triethylene glycol dimethacrylate) and gellan were prepared by two methods. The first method was aqueous suspension polymerization in the presence of N-butyl acetate as porogenic agent when the crosslinking and grafting reactions were achieved in a single step. The second method was based on the reaction between hydroxyl groups belonging to gellan and the epoxy groups situated on the surface of porous microparticles based on glycidyl methacrylate and dimethacrylic monomers in basic medium. The microparticles with and without gellan were characterized by Fourier transform infrared spectroscopy, SEM, AFM and TGA. Also, the porous structure was investigated in terms of pore volume, porosity and specific surface. The swelling behaviour in aqueous solution with different pH values as well as sorption studies of cefuroxime sodium salt onto porous microparticles were investigated. The presence of gellan in the structure of the microparticles leads to porous materials characterized by higher specific surface areas (S sp = 78-140 m 2 g-1), higher swelling capacities (S w = 162%-365%) and higher sorption capacities of the drug (q e = 101-147 mg g-1) compared to microparticles without gellan in their structures (S sp = 73-85 m 2 g-1 ; S w = 139%-209%; q e = 70-110 mg g-1).

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The in situ spectroelectrochemical cyclic voltammetric studies of the antimony-monocapped nickel(II) and iron(II) tris-pyridineoximates with a labile triethylantimony cross-linking group and Zr(IV)/Hf(IV) phthalocyaninate complexes were performed in order to understand the nature of the redox events in the molecules of heterodinuclear zirconium(IV) and hafnium(IV) phthalocyaninate-capped derivatives. Electronic structures of their 1e-oxidized and 1e-electron-reduced forms were experimentally studied by electron paramagnetic resonance (EPR) spectroscopy and UV−vis−near-IR spectroelectrochemical experiments and supported by density functional theory (DFT) calculations. The investigated hybrid molecular systems that combine a transition metal (pseudo)clathrochelate and a Zr/Hf-phthalocyaninate moiety exhibit quite rich redox activity both in the cathodic and in the anodic region. These binuclear compounds and their precursors were tested as potential catalysts in oxidation reactions of cyclohexane and the results are discussed.