Overall, considering the current literature picture on the genetics of bruxism, the genes described so far can be grouped into two main categories: (i) brain-related genes, such as metalloproteinase genes (MMP2, MMP9), catechol-o-methyltransferase genes (COMT) [20], dopaminergic genes (DRD1, DRD2, DRD3, DRD4, DRD5) [21,22], serotonin receptor genes (5-HT1A, 5-HT2A) [23], and genes involved in stress regulation (NTRK2, BDNF) [24], and (ii) genes related to muscle activity regulation, such as ACTN [25] and MYO3B [19] genes. This evidence concerns the gene COMT and bruxism.