# Magnetism in Dentistry: Review and Future Perspectives
## 2 Tissue Engineering
### Scaffold Design Strategies
Interesting approaches involve the use polymers and hydrogels of materials that can modify their behaviour as response to an endogenous and/or exogenous stimulus, at the same time allowing the delivery of the required amount of drug on-demand [36; 37; 38]. Oral controlled-release drug delivery carrier has been developed adopting pH-responsive bacterial cellulose-g-poly(acrylic acidco-acrylamide) hydrogel [38], or a poly(ethylene glycol) hydrogel loaded with drugs by \(\beta\)-eliminative linkers [39]. PH-responsive drug release capability has been also demonstrated for famesol-loaded nanoparticles, composed of 2-(dimethylamino)ethyl methacrylate, butyl methacrylate, and 2-propyl acrylic acid [40]. Multifunctional nanoparticle-based drug delivery systems represent another intriguing strategy in bone repair. For example, mesoporous silica nanoparticles have been decorated with a bone-forming peptide and encapsulated into arginine-glycine-aspartic acid-treated alginate hydrogel [41]. Biomimetic drug delivery systems have been also obtained employing dendrimers, hydrogels, liposomes, micelles, polymeric carriers, and their nanostructures [42; 43]. Dental and periodontal regeneration has been promoted employing smart biomaterials and constructs, such as multi-layered structures. In this context, bilayered PLGA/calcium phosphate structures or tri-layered nanocomposite scaffolds based on PLGA reinforced with nanobioactive glass ceramic and/or growth factors have been developed [44; 45]. PH responsive smart dental resins have been adopted in tooth structures preservation and protection, by analysing, i.e., dental composites containing nanoparticles of amorphous calcium phosphate and tetracalcium phosphate [46]. PH-sensitive materials are characterized by a selective inhibition of acid-producing bacteria. Examples are cationic poly(phenylene vinylene) derivative, and pH-sensitive quaternary pyridinium salts, for which the antibacterial potency can be controlled by varying the pH [47; 48]. Furthermore, oral biofilm composition could be modulated by advanced and smart resins, at the same time avoiding drug resistance. Dental resins containing quaternary ammonium methacrylates such as 12-methacrylology dodecyl pyridinium bromide, methacrylylethyl cetyl dimethyl ammonium chloride, quaternary ammonium polyethylenimine, and dimethylaminododecyl methacrylate showed the ability to decrease the biofilm viability and lactic acid production [49; 50; 51]. Antibacterial-coated material to enhance wound healing and tissue regeneration have been developed adopting different absorbable or non-resorbable, natural/synthetic materials, also assessing mechanical properties, and bacterial adherence [52]. It is worth noting that the oral cavity hosts a plethora of tissues with diverse functions. This complex environment hosts cells, bacteria, viruses, and fungi [53]. Several studies highlighted potential correlation between dental procedures (i.e., surgical and non-surgical), periodontal disease, systemic, and/or cardiological diseases (i.e., infective endocardiits) [54]. Cardiovascular and neurological disorders should be correlated with low-grade chronic inflammation by periodontal pathogens [54]. This complexity of factors offers the healing particularities and challenges for further studies in the oral cavity treatments [53].