## 2 Nanomaterials in Endodontics
### Nanodiamond  
Almost half of the human population suffers from dental caries (which is caused by acid-forming bacteria, the most dangerous of which is the _Streptococcus mutans_ bacterium), while the sixth disease most often affecting people in the world is periodontal disease (11.2%), especially of the gums, which are attacked by the Gram-negative bacterium _Porphyomonas gingivalis_. The communities of microorganisms found in the oral cavity form a very complex structure--the biofilm--which is the main cause of infection. The analysis of phenomena related to the formation and ultimately the removal of biofilm from the oral cavity is very important, considering that the bacteria causing tooth and gum diseases are associated with various systemic diseases. It is suspected that biofilm influences the development of Alzheimer's disease, as well as cardiovascular diseases and obesity. In other words, fighting biofilm in the oral cavity also means fighting the most serious diseases that plague humanity [167]. Biofilm, due to its complexity, is characterized by a high resistance to conventional antibiotics, which is why intensive work is being carried out to search for alternative therapies.  
Promising research results were presented in the groundbreaking work of Prof. [PERSON] et al. [168]. Their research concerned the standard of endodontic treatment, which is filling a mechanically and chemically prepared root canal with gutta-percha. Gutta-percha is a plastic material, volume-stable in cold techniques, biocompatible, non-resorbable, impermeable to bacteria and non-staining of the teeth. Moreover, the presence of zinc oxide in gutta-percha points gives them some antibacterial properties. However, the main disadvantage of gutta-percha points is the lack of adhesion to the dentin, which does not ensure the tightness of the filled canal and requires the use of a sealing material [169]. Faced with these problems, the team of Prof. [PERSON] proposed modifying gutta-percha with amoxicillin-coated nanodiamond particles. The effect of these studies was, first of all, the confirmed inhibition of biofilm growth, and in addition, tomographic imaging showed that the degree of the filling of the canal with new material was better than in the case of conventional gutta-percha [168].  
Moreover, the team led by Dr. [PERSON] and Dr. [PERSON] has shown in experiments that diamond nanoparticles have a strong antibacterial effect on planktonic cells and interfere with the deposition of these cells on tissue surfaces, hindering the growth and formation of biofilm [170].  
Recent publications by a team of scientists from Taiwan have revealed the potential of nanodiamonds as ingredients in irrigation fluids. After the mechanical cleaning of the tooth canals, it is necessary to remove the smear layer. For this purpose, sodium hypochlorite and ethylenediaminetetraacetic acid are most often used, but the disadvantage of this solution is the weakening of the dentin and the low susceptibility of organic substances in the smear layer. Scientists proposed the use of nano and submicron diamond particles in irrigation solutions, the effect of which was additionally enhanced by sonic and ultrasonic oscillations. The high effectiveness of removing the smear layer from the walls of dental canals and canal apices was confirmed by scanning microscopy [171].