Plant polyphenols and oral health: old phytochemicals for new fields

Despite the protective role of diets rich in fruit plant polyphenols against some cancers and chronic degenerative and inflammatory diseases, insufficient emphasis has been placed on oral health. Numerous studies have aimed to ascertain the role of polyphenols in the prevention and treatment of oral diseases; however, even when in vitro evidence appears convincing, the same is not true for in vivo studies, and thus there is a general paucity of solid evidence based on animal and clinical trials. To the best of our knowledge, only two reviews of polyphenols and oral health have been published; however, neither considered the potential role of whole plant extracts, which contain mixtures of many polyphenols that are often not completely identified. In the present study, our main aim was to review the current state of knowledge (search period: January 1965 to March 2011) on the effects of plant extracts/polyphenols on oral health. We found data on grapes, berries, tea, cocoa, coffee, myrtle, chamomile, honey/propolis, aloe extracts and the three main groups of polyphenols (stilbenes, flavonoids and proanthocyanidins). Their effects on caries, gingivitis, periodontal disease, candidiasis, oral aphtae, oral mucositis, oral lichen planus, leukoplakia and oral cancer were investigated. The data suggest that there is a lack of strong evidence, in particular regarding randomized clinical trials. However, a fascinating starting point has been provided by pre-clinical studies that have shown interesting activities of polyphenols against the most common oral diseases (caries, periodontitis and candidiasis), as well as in oral cancer prevention.