PTGES and periodontal disorder: In particular, the following genes were considered: ALP (alkaline phosphatase), a typical osteogenic marker [31, 32], OPN (osteopontin), an osteogenic marker also implied in inflammatory processes [33, 34], RANKL and OPG, fundamental proteins for bone remodeling and homeostasis [6, 7, 10, 11], and COX-2 and mPGEs (cyclooxygenase-2 and prostaglandin-synthase), two enzymes involved in the synthesis of prostaglandins, well known inflammatory mediators involved in bone metabolism and periodontal disease [35–37].