For deep sedation procedures, supplemental oxygen is usually administered via a nasal cannula to the patients. Non-invasive mechanical ventilation (NIMV) is the oxygenation method, especially used in the treatment of hypoxia. We aimed to compare the use of nasal cannula and NIMV applications as oxygenation methods for deep sedation procedures in the dental treatments of children, especially in terms of patient safety and the convenience of the dentist to apply the treatment. Patients were divided into two groups as the nasal mask group (M) and the nasal cannula group (N). For oxygenation, while a nasal cannula was used for group N, NIMV with a nasal mask was applied for group M. Hemodynamic parameters of the patients, complications and dentist's satisfaction degree were recorded and compared. Saturation of blood oxygen (SpO2) was significantly higher in group M after induction of anesthesia and in the fifth minute of the procedure. Hypoxia (SpO2 ≤90) event number during the procedure was significantly higher in group N. Surgeon satisfaction was significantly higher in group M. We concluded that, in children undergoing deep sedation for dental treatments, NIMV applied with a nasal mask reduces the risk of hypoxia and is safer than using a nasal cannula.