While this is a promising start, many questions remain. Those include, among others, patient comfort with differing pressures, the obligatory need to keep the mouth sealed shut all night with the device, further examination of the position of the tongue that might potentially occlude the airway orifice on an individual basis, the possible need for heated or room-temperature humidification, the need for a nose clip to prevent nasal breathing or leakage on an individual basis, its use with an edentulous patient, the potential that the flexibility of the soft tissues of the mouth such as the cheeks may produce discomfort with distension from mouth pressure (particularly if higher pressures are required), and the possibility of sex differences in response to oral CPAP. Furthermore, although the study suggests that the airway mechanics are similar during oral and nasal CPAP during non-rapid eye movement sleep, only a select few measurements were made, and there is no description of whether body or head position or rapid eye movement (REM) sleep had any effect on the results. These conditions may potentially affect the results by putting pressure or stress on the mouth (head position), by relaxing the upper airway (REM sleep), or by increasing pressures to prevent airway collapse and maintain airway patency (head position, body position, or REM sleep). In addition, as with any occlusion of the mouth, there is the hypothetical possibility of the aspiration of stomach contents should the patient regurgitate during the night and not be able to expel the emesis through an occluded mouth. Of note, this is also a hypothetical possibility with a full-face mask1–2 but there are few if any documented cases of this occurrence.