This is a removable plastic cover/splint usually used for the upper teeth and it separates the rows of teeth when biting. Occlusal splints are normally worn at night to prevent the patient from grinding their teeth. They are usually employed where there is pain in either the jaw joint or the chewing muscles which is summarized as craniomandibular dysfunction and to protect against abraded dentition.
In the best case scenario, occlusal splints break an entrenched pattern of movement and resulting in a non-specific relaxation effect. A number of different types of occlusal splints have been developed but they all work in more or less the same way. For this reason, it is always best to choose a simple, cost-effective design that is safe to wear for long-term use.
The Michigan-Splint is the one that generally fulfills these criteria. Only in heavy grinders who often grind on the Michigan Splint as much as before, another splint can be used which just covers the front teeth. These frontal bite splints lead to a reduction of the overactive masticatory muscles via the pain stimulus on the front teeth and in this way, even support heavy grinders.