Research progress on multifunctional natural antioxidants in oral therapies

Oxidative stress is closely associated with the development of oral diseases such as caries, periodontitis and endodontitis. The accompanying oxidative stress during inflammation could aggravate tissue damage. However, numerous studies have shown that some dental materials, such as composite resins, bleach, drugs for root canal irrigation and dental implants, can give rise to abundant free radicals, which have adverse effects on peripheral tissues. Therefore, it is essential to supplement with extra antioxidants against free radicals. Plant-derived natural antioxidants have attracted great attention in biomedicine because of their excellent biocompatibility and easy access. This paper focused on the redox imbalance in the oral cavity and the application of natural antioxidants to oral therapy and their modification of dental materials. Current research shows that by constructing polyphenol-based metal organic nanoenzymes or adding vitamins and polyphenols to bionic hydrogels, the safety and utilization rate of antioxidants can be significantly improved. However, these polymer delivery systems have problems such as poor degradability, hepatotoxicity and nephrotoxicity, and the research is still in its infancy. In terms of material modification, it is crucial to choose the type and ratio of natural antioxidants and raw materials, as well as appropriate modification methods. A strong chemical bond between the antioxidant and the raw material may lead to the failure of antioxidant release from the modified composite, lowering the antioxidant activity. At the same time, the selection of polyphenols rich in pyrogallol functional groups can retain more free phenolic hydroxyl groups after chemical modification, which is conducive to greater antioxidant activity by the implant materials. Although research on natural antioxidants in oral therapy has made progress, there is a lack of data supporting clinical trials and long-term application effects, and further research is still needed.