As the name implies, this splint was developed in Michigan University by Professors Major Ash and Sigurd P. Ramfjord. It is a stabilization splint with a cuspid rise and freedom in centric occlusion used in the management of bruxism as well as a diagnostic tool for TMJ. As it covers all the teeth of one jaw it is also referred to as a full-coverage splint.
Uneven bite surfaces often are the contributing factor in bruxing. The aim of the Michigan stabilizing splint is to prevent this interference so that the jaw can move smoothly. It is used to bring relaxation of the masticatory muscles by increasing the vertical dimension. This leads to the condylar head (the rounded part of the lower jaw that connects to the joint) of the lower jaw hinging open with slight forward displacement. It therefore reduces the pressure on the intra-articulator disc, the pad of tissue found in the joint. This helps to relax jaw muscles and to reduce the pain caused by clenching of the jaws. It is generally made of hard acrylic and is flat on the surface which ensures that all the teeth of the opposite side touch the splint simultaneously. This helps reducing the bite force making it useful for treating occlusal trauma. It protects the teeth and restorations from wear caused by clenching and grinding.
Considerable clinical skill is necessary to fit this specially made device on the upper teeth. It is based on the concept of canine guidance wherein the back teeth do not touch each other during lateral movements of the jaw. This protects the back teeth and any restorations in this area from the effects of grinding.