Orthodontic appliances and aids, namely, appliances for the treatment and training of teeth, dental arches, tongue, intra-oral musculature and facial muscles; dental devices, namely, intra-oral appliances for training the tongue, lips and intra-oral musculature, in particular active intra-oral appliances for training the tongue, lips and intra-oral musculature; dental devices, namely, intra-oral appliances for treating and supporting cranio-mandibular joints, including the temporomandibular joint; dental devices, namely, intra-oral appliances for treating teeth clenching and bruxism; dental devices, namely, intra-oral appliances for assisting with oral-facial development, in particular chewable intra-oral appliances for assisting with oral-facial development in children; dental devices, namely, appliances for treating breathing disorders, including sleep breathing disorders; dental devices, namely, intra-oral appliances for treating snoring and sleep disorders, in particular active intra-oral appliances and mandibular advancement splints; dental devices, namely, intra-oral appliances for strengthening the tongue, lips and facial muscles; dental devices, namely, intra-oral appliances with protrusions for assisting with oral hygiene and treating periodontal disease, in particular chewable intra-oral appliances with brush-like protrusions; dental devices, namely, intra-oral appliances with protrusions for improving the health of teeth and gums, in particular chewable intra-oral appliances with brush-like protrusions