# Antibacterial Bio-Based Polymers for Cranio-Maxillofacial Regeneration Applications
## 3 Scaffolds and Implanting Medical Devices for Soft and Hard Maxilofacial Tissues
### Dental Implants  
Titanium (Ti) implants constitute a globally accepted device in dental restoration for substituting missing teeth due to their excellent mechanical and chemical properties, their good corrosion resistance, and biocompatibility. However, some inevitable mechanical or biological complications such as mucositis, peri-implantitis, and marginal bone resorption can result from the apparition of bacterial biofilms on their surfaces [34; 35; 36]. In this sense, numerous approaches have been proposed to functionalize titanium surfaces by using anti-adhesive polymers to inhibit biofilm colonization [85]. For instance, polysaccharides such as chitosan and hyaluronic acid have been demonstrated to inhibit bacterial adhesion to titanium by interfering with surface linkage between titanium and the biofilm forming bacteria (Figure 4) [35; 86; 87; 88]. The antibacterial effect resulting from the combined properties of these two polysaccharides, via reducing the hydrophobic interactions and van der Waals forming forces, diminished bacterial adhesion [35; 89].  
Figure 3: Biodegradable, synthetic scaffolds (poly(lactic-co-glycolic) acid (PLGA)/PCL blend (PP), silver-modified/collagen and polydopamine (pDA)) as materials used for the fabrication of oral and craniofacial guided tissue regeneration (GTR) materials. Reprinted with permission from [PERSON] et al. 2019 [54], with permission from Copyright 2019 American Chemical Society.  
Functionalization with bioactive compounds is another approach to avoid bacterial fixation, one of the greatest disadvantages of the coatings of dental implants [85]. For example, [PERSON] et al. incorporated silicon nitride into polyetheretherketone (PEEK), a polymeric biomaterial used for trauma, prosthodonics, maxillofacial, and cranial implants, demonstrating significant bacteriostatic properties against Gram-positive _Staphylococcus epidermidis_[90]. In this way, some composites of nanostructured coatings based on bio-based polymers have been investigated showing great potential. For example, [PERSON] et al. used a nano spray-dried antibacterial coating consisting of biodegradable PLGA and nonfloxacin against _E. coli_ achieving a 99.83% reduction in the number of bacterial colonies [91]. In another approach, [PERSON] et al. tested the efficacy of silver-conjugated chitosan nanoparticles as a prospective coating material of titanium dental implants, reporting that the chitosan-based coating exhibited a high inhibitory effect on the growth of _S. mutans_ and _Pseudomonas gingivalis_, inhibiting bacterial adhesion and reducing biofilm formation [36].  
Looking to the future, the major challenge of these kinds of bio-based-polymeric coatings is the prevention of bacterial biofilm formation through antibacterial surface activity, while not affecting the viability of osteoblastic cells. For this reason, the need to study composite systems has increased in recent years, seeking the promotion of the proliferation and differentiation of native cells, while using antibacterial agents to prevent the development of infections [85].