## 3 Discussion
Nanoparticles show an increased hydration rate compared to conventional-sized particles of the same substances, which in turn results in a shorter setting time and a higher microhardness value. This is particularly important because teeth are naturally exposed to various types of pressure and load; therefore, the supplementary material must have properties as close as possible to natural tissue, so that it is possible to reproduce the biomechanical conditions in the mandible and maxilla [58; 65; 147; 151]. Despite so many indisputable advantages and the almost unlimited possibilities of using nanoparticles in the scientific world, as well as supporters of such innovative solutions, there are also opponents whose opposition is based on specific arguments. The scale of research currently being conducted is limited to the observation and assessment of the properties of materials in the form of samples conditioned in a simulation environment, the analysis of results obtained on the basis of cell cultures in laboratory conditions, and research using laboratory animals. These studies are short-term and do not allow us to formulate clear conclusions about how the use of nanomaterials affects tissues and the body in the long term. The interactions between nanomaterials and living organisms are very complex, which is why they are still the subject of intensive scientific research. The main concerns relate primarily to potential toxicity, especially with long-term exposure to high concentrations. This is a very important aspect because the mechanisms of toxicity may include inflammatory reactions, oxidative stress and also DNA damage. Once released into the bloodstream, nanoparticles can spread throughout various organs and tissues, affecting their functioning in unexpected ways; they may therefore disturb cell proliferation, differentiation or functions. Moreover, the introduction of nanomaterials into the body may lead to the activation of the immune system. The immune response to nanomaterials can be complex and depend on many factors, including the physicochemical properties of nanomaterials. Even nanomaterials from the same material may exhibit different behavioral properties in relation to individual cellular tissues. This may be due to differences in size, shape, surface or degree of functionalization [156; 164; 190]. It is important to remember that materials used in dentistry operate in an environment that promotes degradation, so in addition to being effective in treatment, they should demonstrate chemical stability. However, some research actually suggests that some materials--including dental fillings--may release chemical compounds that may potentially affect patients' health [82; 169; 183]. Conducting scientific research that thoroughly assesses the impact of nanomaterials on living organisms, including the oral environment, the immune system and potential long-term effects, is essential to understand their impact on surrounding tissues. Such research is key to developing guidelines and regulations for the use of nanomaterials in dentistry, and providing sound scientific data will also enable the development of innovative nanotechnology-based dental products that can be used with greater confidence in their safety and effectiveness.