Hi Guys, I am a specialist dentist ( Orofacial Pain & Oral Medicine) and "nightguards" or "occlusal splints"
can be effective and reduce migraine attacks in some patients. However, you need to have the correct splint. I advise a full coverage splint, covering all the teeth in one arch, either top or bottom. They need to be made of HARD acrylic with a soft internal lining.
A soft "chewy" splint encourages grinding while you sleep and can worsen the problem.
Hope this helps