I wear a mouth guard as well with my Cpap and sleep well. Have you had your sleep apnea evaluated? That could be a cause for the restless legs. If you have sleep apnea, you could be moving your legs upon arousals from apnea that you may not be aware of. If you get the apnea fixed it could take care of the leg issues, too. If you haven't been evaluated, it might be worth looking into.