# Magnetism in Dentistry: Review and Future Perspectives
## 2 Tissue Engineering  
Aspects related to the engineering and manufacturing of \"replacement tissue\" are often identified with the term \"tissue engineering\" (TE), thus providing organ analogues, which are obtained from patients' own cells, and functional tissues, offering an alternative method to grafts or transplants [9]. This method became increasingly important in dental and maxillofacial regenerative medicine, providing novel opportunities for the reconstruction of periodontitis, teeth, bones, oral mucosa, skin, conjunctiva, temporomandibular joint, cartilage, bone, nerves, muscles, tendons, and blood vessels in the oral/maximillofacial area [9].  
TE represents a valuable alternative for specific tissue defect reconstruction, because of the available bioengineered resources. Current treatments recognized as gold standard are often related to many disadvantages for patients, such as loss of motor and sensorial functionalities of craniofacial structures, high risk of inflammation and infection, or unpredictable compatibility for autologous grafts [11].  
Three pillars support tissue engineering: (i) Stem cells/progenitor cells, which are responsible for the synthesis and deposition of new extracellular matrix (ECM); (ii) signalling/growth factors for promotion of functionalities; (iii) scaffolds, as a support for cell adhesion, proliferation, and differentiation, as well as for the aspects related to ECM biosynthesis (Figure 1).  
Figure 1: Tissue engineering paradigm.  
Cells communicate with each other and with their environment, being influenced by different aspects concerning scaffold biomaterials, surface chemistry, topography, and roughness [12; 13]. The combination of cells, scaffold and signalling pathway is responsible for correct damaged tissue replacement, with similar function to the original tissue or with the capability of stimulating the regeneration of the damaged tissue [14; 15]. Stem cells, chondrocytes, fibroblasts, and keratinocytes derived from human or animal origin have been adopted in clinical studies towards tissue engineering and regenerative medicine [16].  
Scaffolds and biomaterials represent crucial elements in dental tissue engineering, since they can be adopted as: (i) adhesion sites for surrounding tissues cells during the regeneration, (ii) template for tissue regeneration, (iii) source of implantable odontogenic cells which are capable to differentiate into required cell type, and (iv) carrier for bioactive molecules, such as growth factors, which may improve regenerative potential [17; 18].  
Tissue engineering approach involves cells and biomaterials, adopting an array of scaffold design and optimization strategies.  
A wide variety of biomaterials is widely employed in oral and maxillofacial TE strategies. Examples are natural organic, synthetic organic, or even inorganic materials.  
Natural organic materials include peptides (e.g., gelatin and collagen) and polysaccharides (e.g., agarose, alginate, chitosan). Synthetic organic materials which are commonly used are poly(lactic acid) (PLA), poly(caprolactone) (PCL), poly(lactic-co-glycolic acid) (PLGA), and poly(glycolic acid) (PGA) [19].  
On the other hand, examples of the most used inorganic materials in bone replacement are glasses or calcium phosphates (e.g., \(\beta\)-tricalciumphosphate, hydroxyapatite,) and cementitious complexes of calcium silicate or calcium phosphate [20].