TNFRSF11B and obstructive sleep apnea syndrome: Hypoxia and hypercapnia present in patients with OSA have been shown to be related to the apoptosis of periodontal cells [45], that may increase the production of pro-inflammatory cytokines and stimulate transcription factors such as the nuclear transcription factor (NF-κβ) [46]; this factor is involved in the periodontal bone loss [47,48] mediated by the increase of RANKL/OPG (Receptor activator of NF-κβligand/Osteoprotegerin) axis ratio that activates the osteoclastogenic process [37].