A jig splint (synonyms: Front bite splint, relaxation splint, reflex splint, relaxation plate, relaxation aid) is used to relieve pressure on all structures of the masticatory system with the aim of reducing bruxism (teeth grinding and clenching) and normalizing muscle function. We use our masticatory system not only for grinding food. It is put under much greater strain every day by the fact that we unconsciously – during the day and at night – relieve stress by grinding or clenching our teeth, so-called bruxism. However, the forces acting on the structures of the masticatory system (teeth, muscles and temporomandibular joints) during stress management are many times higher and last much longer than the forces needed to grind food. While about ten minutes of tooth contact throughout the day is sufficient for food intake, the structures of the craniomandibular system (the masticatory system consisting of teeth, masticatory muscles, temporomandibular joints and adjacent bone and soft tissue structures) are subjected to non-physiological stress by bruxism for several hours every day. It is important to break this cycle, which overloads not only the masticatory system but also structures of the musculoskeletal support system during grinding or pressing. This is where the jig splint comes in. It prevents the build-up of unphysiologically high forces by means of a small anterior plateau (biting surface in the area of only two incisors) – comparable to biting down on a grain of food and the immediate reflex reduction in chewing force. The jig splint thus belongs to the so-called reflex splints. Unlike a Michigan splint, for example, it is not an adjusted positioning splint that sets the lower jaw in a defined position relative to the upper jaw and in which all teeth are in contact. The bite block in the area of the central incisors eliminates occlusal contacts (contacts of the posterior tooth surfaces). This nonocclusion in the posterior region eliminates possible interference (interfering contacts located in the occlusal region of the posterior teeth). Desmodontal propioceptors (receptors of the periodontal apparatus) no longer provide information to the CNS (central nervous system), which in turn does not trigger muscle contractions to compensate for the interferences and a resulting muscle discoordination. The contact area in the anterior region, which is kept small, means that no unphysiologically high chewing forces can be built up. This is because biting down on the small-surface jig (= “bite table made of plastic”; bite plateau) immediately triggers a reflex reduction in the tone of the adductor muscles (mouth closure) and also the neck muscles. If short-term therapy is successful, the jig splint thus leads to relaxation of the musculature and the mandible can adjust to a physiological position resulting from the relaxed musculature and temporomandibular joint position, but not from possibly disturbing contact zones on the occlusal surfaces of the posterior teeth. Other splints also work with an approach comparable to the Jig splint: The so-called Hawley plate and the Sved plate have extended bite plates over the entire anterior region, while the Immenkamp relief plate does not load the incisors, but instead has two small plateaus in the bite area of the lower canines.
Indications (areas of application)
- For rapid relief of the masticatory muscles.
- Usually as a short-term therapy for the initial treatment of muscular dysfunction.
- For long-term therapy for nocturnal carrying
- For normalization of muscle function
- To adjust the mandible to a physiological position not forced by muscle tension.
Contraindications
Wearing the jig splint too long and especially continuously, not only at night but also during the day, can lead to extrusion (lengthening) of the posterior teeth and intrusion (Latin-English : penetration) of the lower anterior teeth. Therefore, the wearing time should not exceed one and a half weeks as a rule.
The procedure
I. Dentist
- Impressions of both jaws – e.g. with alginate impression material.
- Facebow creation – for transferring the individual temporomandibular joint positions to the laboratory.
- Bite taking in habitual occlusion (habitually adopted static occlusion/closure = contact between the teeth of the upper jaw and the lower jaw) – to transfer the positional relationship of the lower and upper jaw to the laboratory.
II. dental laboratory
- Making plaster models based on the impressions.
- Model assembly in the articulator (device for imitating temporomandibular joint movements) by means of the facial bow and bite registration
- Fabrication of a deep-drawing splint on the maxillary model – A 1 mm thick, crystal-clear thermoplastic film is heated until plasticized and then “deep-drawn” over the teeth of the plaster model using a vacuum process.
- After cooling, the edges of the splint are shortened so that they leave the gingiva (the gums) uncovered, but extend so far beyond the buccal equator of the tooth (widest protrusion of the tooth towards the cheek side) that they end in the underneath areas lying between the equator and the gingiva, thereby causing the retention (the hold) of the splint.
- A so-called key is made from silicone impression material, which is located in the anterior palatal region and forms a plane parallel to the occlusal surfaces over the premolars (anterior molars) and anterior teeth, about 1 mm thick.
- In the area above the two central incisors, the silicone is cut out above the deeply drawn splint. The resulting recess is filled with cold polymerizing MMA-based resin (methyl methacrylate) and cured.
- After polymerization (setting reaction by linking monomer plastic molecules, thereby curing), the bite plateau – the jig – is worked out and polished.
III Dentist
- Insertion of the splint
- Wearing instructions – wearing the splint at night. If the splint is also worn during the day, speech is difficult. During the meal, it must not be worn.
After the procedure
- After successful muscle relaxation, positioning of the mandible in the new physiological position using an adjusted positioning splint.
- Interdisciplinary, further therapy measures (physiotherapy, osteopathy, jaw / orthopedics, functional diagnostics, measures for stress management, etc.).
Possible complications
- Hypersensitivity to MMA plastic
- When worn all day: extrusion (from lat. : extrudere = pushing out, -driving out) of the posterior teeth, intrusion (lat.-engl. : penetration) of the central lower incisors.
