Intra-oral appliance, namely, therapeutic mouthpieces for treating sleep disorders for medical purposes, intra-oral appliances for treating teeth clenching and bruxism; dental training device for teeth, tongues and facial muscles, namely, dental devices for massaging the teeth and gums, promoting natural chewing and improving teeth alignment, bite issues and oral-facial muscular development; medical device to alleviate or prevent snoring; dental device, namely, a soft flexible mouthguard-like appliance that pulls the mandible forward and optimizes airways for breathing to assist with symptoms of sleep apnea; chewable dental device for assisting with oral-facial development in children; chewable dental device that promotes optimal function of oral-facial area in adults; chewable dental device that promotes healthy development of teeth, lip and tongue strength in children; dental device that promotes nose breathing; dental device, namely a flexible mouthguard-like device that reduces teeth clenching and damage to teeth; dental device with brush-like protrusions that assists with the treatment of periodontal disease, not being toothbrushes; dental device for improving speech and oral motor function; dental device for the treatment of tempero-mandibular joint dysfunction; dental device which has brush-like protrusions that can be used to assist in oral hygiene