[ Oral appliance in the nature of a flexible mouthpiece to promote nasal breathing while asleep and/or awake for sleep apnea treatment; ] Oral sealing device in the nature of a flexible mouthpiece to mitigate air loss through the mouth while using continuous positive airway pressure (CPAP) for sleep apnea treatment; flexible mouthpiece to minimize snoring by decreasing mouth breathing while asleep; oral sealing dental device in the nature of a flexible mouthpiece for use with sleep apnea trea...