I am a dentist working in dental sleep medicine. Oral sleep apnea appliances have been around twenty or more years now. Given that length of time, they have been extensively tested and we now have a large body of test data about their efficacy. Actually, they have been found to be quite effective in treating both mild and moderate sleep apnea and are considered a first line treatment for both, as well as CPAP. I believe that many of the same oral appliances found in the USA are also available in Canada. A MyTap appliance can be had in the USA for about $650(US) and is quite effective. However, it is not very strong or long-lasting. It does make a great starter appliance for someone trying to see it the concept works for them. Please understand though, that these work only for obstructive sleep apnea and not for central sleep apnea. Arthur B. Luisi, Jr., D.m.d.