# Nanomaterials in Craniofacial Tissue Regeneration: A Review
## 3 Clinical Applications
### Vascular Tissue Regeneration (Endodontics)
#### 3.2.2 Root Canal Therapy  
An alternative direction involving the use of nanomaterials in endodontics is to improve root canal therapy itself by improving the armamentarium, specifically the obturating material. The obturating material is the filling used in root canal therapy to replace the pulp tissue within the cement of the injured tooth. The most commonly used obturating material to date is gutta-percha, as its bioinert properties make it a good choice. While it is the most widely used material for root canal therapy, it has many mechanical and functional disadvantages, including its pliable, non-adhesive, and minimal antimicrobial property, and can easily be displaced in the presence of pressure [39]. Furthermore, the use of gutta-percha can lead to microleakage post-therapy, as its thermoplastic property can lead to shrinkage, creating gaps and microleakages [39; 40]. Current studies look to overcome these disadvantages by exploring the use of nanomaterials. Because nanomaterials are composed of nanoparticle structures, there is an increase in contact surface area, which ultimately reduces gaps and microleakages, in addition to increasing the antimicrobial property and superficial dentin flexural strength of the obturating materials [34; 39].  
One material that can be used as such is bioactive glass 45S5. Bioactive glass 45S5, in addition to its nanoparticle feature, has a chemical composition that is similar to that of human bone and dentin, allowing it to bond to bone and making it an excellent choice as an alternative obturating material [40]. However, it should be noted that due to the chemical composition of bioactive glass 45S5--that is it is composed of calcium silicate--retreating protocols cannot be done for root canals that are obturated with only bioactive glass 45S5 [40]. However, this problem can be overcome by using bioactive glass 45S5 (or any other calcium silicate-based materials) in conjunction with a matrix polymer such as that of gutta-percha [40]. [PERSON] et al. explored the use of bioactive glass and gutta-percha and showed the adherence of the obturating material to dentin without the use of a sealer as used in the conventional root canal therapy protocol [41]. In a more recent experiment by [PERSON] et al., they thoroughly explored the properties of bioactive glass in combination with gutta-percha as an obturating material compared to gutta-percha only [42]. Their study revealed that the former had enhanced thermal properties as it had lower melting points, which was optimal in the case of a retreatment procedure [42]. [PERSON] et al. provided further evidence for the promising use of bioactive glass to improve endodontic procedures by showing that the incorporation of bioactive glass to gutta-percha enhanced its antimicrobial properties due to its high alkalinity property and had excellent radiopacity results [42]. The use of nanomaterials in endodontics extends far beyond bioactive glass; other nanoparticles than can be used as a filling in conjunction with gutta-percha also include silver nanoparticles, chitosan nanoparticles, and zinc oxide nanoparticles [43].