How effective can a dental appliance be in treatment of sleep apnea over cpap?

Very effective: An oral appliance an be as effective as CPAP for patients with mild or moderate sleep apnea. It can be used for patients with severe sleep apnea who cannot tolerate cpap. See a dentist that treats sleep apnea and find out if this will work for you.

Only if you wear it.: They work very well. The ones i've made are especially useful when traveling. They are a lot less cumbersome than a cpap.

Depends: An oral device for sleep apnea can be very effective, but the CPAP is still the "gold standard" of care. But there are many types of dental sleep mouthpieces and there is no one mouthpiece that works for every patient. I would not consider buying one online or at a retail store. Improper fit can create tmj/tmd, move teeth and create many problems. See a dental specialist, but also consult with.