Few studies have evaluated the interaction between conventional complete dentures (CCD) and the respiratory system and the authors are unaware of any that evaluated the interaction between implant-retained overdentures (IROs) and the respiratory system. This clinical report documented the effects of wearing an IRO on the cardiorespiratory stability of an edentulous patient with obstructive sleep apnea (OSA). A 64-year-old woman was referred to the department of otolaryngology because of daytime sleepiness and morning headaches. The patient refused polysomnographic evaluation because of claustrophobia. Overnight pulse oximetry (PO) was performed to detect cardiorespiratory stability during sleep, and the oxygen desaturation index (ODI) of the patient was found to be 20.9. A mandibular advancement device (MAD) was fabricated; however, the patient did not comply with the treatment and stopped using the MAD because of intraoral discomfort. Therefore, the patient started to wear the conventional complete dentures (CCDs) nocturnally to prevent upper airway collapses. Despite the significant drop in ODI score to 12.6, because of displacement, the mandibular denture was converted to an IRO. The PO tests performed after another 6 months revealed an ODI score of 7.8. Wearing CCDs might improve respiratory stability of patients with edentulism during sleep; however, more favorable results could be obtained with IROs.