In the following years, more studies confirmed the inhibitory effects of proanthocyanidins and its galloylated monomers on production and/or activity of matrix metalloproteinases MMPs (MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, and MMP-13) involved in periodontitis (Table 1). This evidence concerns the gene MMP1 and periodontitis.