Splint Therapy for Functional Disorders

Splint therapy, as a biomechanical form of treatment, is used for a variety of functional disorders of the masticatory system. The treatment is carried out with occlusal splints and is indicated for:

• Myofascial pain in the TMJ area
• Acute TMJ inflammation
• Arthritic or rheumatic changes to the TMJ
• Parafunctional habits, such as nocturnal grinding and clenching of teeth
• Tinnitus, migraine, and tension headaches
• Vertical increase of occlusion and gnathologic occlusal changes
• Pre-prosthetic therapeutic measures

The terms night guard, occlusal splint, occlusal plane, occlusion rim, occlusal splint, and stabilization splint are used as synonyms to describe the splints in splint therapy. There has been no systematic classification of these devices, so the collective term occlusal splint is used here. Occlusal splints can be classified differently based on their biomechanical effect, occlusal dimensions, and placement (whether in the maxilla or the mandible) as well as the materials used for their fabrication.

Occlusal splints are removable appliances for temporary use that are worn in the maxilla or the mandible. With these intraoral appliances, a new intercuspation position is created within the physiologic centric position of the mandible, and the occlusal relationships between the two dental arches are altered.

Night guards are transparent acrylic occlusion rims for the jaws that are worn at night. They are designed almost flat and have only a few depressions into which the opposing teeth occlude. Because acrylic is softer than teeth, the teeth no longer abrade each other but the guard instead. In addition, the TMJ is unloaded and relieved by a splint.

In addition to myoarthropathies (functional disorders of the muscle and joint complex), malocclusions, and occlusal anomalies, snoring and obstructive sleep apnea can be treated using night guards.

With splint therapy, there is no splinting such as that produced by elastic retentive components on partial dentures. Instead, splints separate the usual occlusion (decoupling the existing intercuspation) so that unloading of overloaded teeth, the muscles of mastication, and the TMJs can occur and faulty occlusal conditions can be corrected. Based on this definition, a splint becomes a therapeutic occlusal guide plate.

Occlusal changes due to elongation must not arise, which is why the splints cover all the teeth and support them antagonistically. These removable splints or guards are simple to fabricate and easy to handle. However, they have an adverse esthetic impact, may impede speech, and will encourage the accumulation of plaque, caries, and gingivitis.

Splints can be made of rigid or flexible acrylic or metal; they are either fixed with clasps or engage the undercuts of the teeth. A mouthguard (or mouth protector), covering the maxillary and mandibular teeth equally, is made from flexible material and is mainly worn for contact sports.

Materials are chosen on the basis of the desired function of the splinting and the properties of the materials:

• Transparent, hard, tough, and torsion-resistant acrylics for universal use
• Light-cured, translucent, or milky composites for occlusal buildups
• Flexible, transparent polyurethane
• Translucent, elastic thermoplastic material
• Thermoplastic acrylate in different grades of hardness and elasticity
• Elastic silicone materials in three grades of hardness and with good recovery properties
• Gold alloys and chrome-cobalt alloys

Classification of occlusal splints according to their biomechanical effect produces four groups (Table 11-1):

1. Reflex splints to interrupt parafunctional habits (eg, bruxism splints)
2. Centric relation splints to restore the centric condylar position (eg, Michigan splint)
3. Eccentric splints to treat disc displacements (eg, repositioning splints, distraction splints)
4. Special forms for a variety of therapeutic approaches