Splints are a customized retainer made from thick acrylic plastic that you wear at night time while you sleep. Everyone clenches and grinds their teeth to some degree while they’re asleep. By wearing a splint, you are protecting your teeth, existing dental work, and relieving the stress on your jaw muscles. The way the splint protects your teeth is it provides a thick barrier between your upper and lower teeth. This barrier absorbs the forces normally felt by your teeth and jaw.