# Antibacterialarial Agents Used in Modifications of Dental Resin Composites: A Systematic Review
## 4 Discussion
### Modification of RBC Compositions
#### 4.2.2 Other Additives
Another invention proposed by [PERSON] et al. [45] that can provide both structural reinforcement and antimicrobial activity is the use of a modified filler consisting of hydroxyapatite (HA) nanodrills coated with polydopamine (HA-PDAs). HA-PDAs were loaded afterwards with silver nanoparticles (AgNPs). The HA-PDA-AgNP nanodrutes were incorporated into a resin matrix. The prepared composite enhanced the strength of the material, while the silver ions released provided antibacterial activity. It was also found that modification with 6-8 wt% HA-PDA-Ag nanowires resulted in a significant increase in modulus and flexural strength. But it should be noted that this modification is appropriate for composites that are thermocured as opposed to photocured because of the color of PDA, which could negatively influence light transmission [45]. An effective modification of dental composites in terms of biocidal effect is the addition of chitosan or chitosan loaded with particles of anhydrous dibasic calcium phosphate (DCPA) [46]. It was found that the modified materials resulted in about 20% less biofilm (_Streptococcus mutans_) compared to the control. Additionally, the modification did not adversely affect the flexural strength, fracture strength, modulus of elasticity, or conversion rate compared to the control group after 90 days of aging in water. [PERSON] et al. [47] used TiO\({}_{2}\) and TiO\({}_{2}\)/Ag nanoparticles for antibacterial modification. Their study showed that the introduction of 2 wt% TiO\({}_{2}\)/Ag nanoparticles reduced the accumulation of _Streptococcus mutans_ biofilm on the surface of a dental composite. TiO\({}_{2}\)/Ag also had a positive effect on the mechanical properties of the material, increasing the compressive strength, while the conversion factor remained unchanged. The surface roughness was also investigated, and it was found that this parameter increased with increasing concentration of nanoparticles. Further research is needed, especially on the issue of cytotoxicity and long-lasting antibacterial activity and the stability of the mechanical properties. [PERSON] et al. [48], in their trials, showed that, in small amounts, Ag-TiO\({}_{2}\) showed bactericidal activity under visible light contact with _Streptococcus mutans_. After incorporation into a composite, however, the photocatalytic properties of Ag-TiO\({}_{2}\) particles were significantly reduced, but a strong bactericidal effect against _Streptococcus mutans_ was still achieved. In this study, no physical/mechanical properties of the composites were evaluated. Bioactive glass derived from Ag-doped sol-gel (Ag-BG) was used as another filler of dental composites [49]. The modifier was used at 5, 10, and 15 wt% concentrations, and bacterial mortality in the biofilm (produced by _Streptococcus mutans_) increased significantly as the concentration of Ag-BG in the composites increased. During the study, the microstructural properties and elemental composition of the developed Ag-BG composite were analyzed. Total strength tests showed that 3 months after immersion in the medium, there was no statistically significant change in the bond of the surrounding tooth tissue to the restorative material. The modification requires further research, and the strength properties of composites should be considered. [PERSON] et al. [50] used ciprofloxacin-loaded silver nanoparticles (CIP- AgNPs) to modify a composite. The use of the modified CIP-AgNPs was shown to achieve biocidal activity against _Enterococcus faecalis_, _Streptococcus mutans_, and saliva microcosms. During the test, it was shown that the compressive strength of the experimental material was higher than that of the control material. The researchers showed that the modified composite materials exhibited biocompatibility compared to composites containing AgNPs. No mechanical properties other than compressive strength were tested, and long-term mechanical testing is needed to determine the real strength over time and under varying environmental conditions. [PERSON] et al.