An oral appliance that is specifically made for sleep apnea and snoring is a custom made device that has two separate pieces, one that covers your upper teeth and one that covers your lower teeth. They might remind you of invisalign trays (but much more durable) or a nightguard (but thinner and 2 pieces). The main difference between an oral appliance for sleep apnea and other oral devices that you might wear at night is the ability of the device to hold the lower jaw forward.