I attended a lecture on sleep apnea in DC and Dr. David Rappoport had this to say about dental devices;
Dental devices, that pull the jaw forward, again, logical, seems like a great idea, should have worked better than it did, does work in enough patients that we are still doing it, but doesn't work quite predictably enough to be a mainstay treatment, certainly not of severe disease.
So, it is possible that it will help, but you would still need a sleep study with the device to determine if it is working. Just because the snoring is reduced doesn't mean that all of the apnea's and hypopnea's have been stopped.
Additionally, there are thousands of "cures" for snoring. Most of them are old wive's tales that vary from ridiculous to dangerous to both. Few of them are effective. The one thing that you can be guaranteed is that they will take your money.
Hope this helps!