What is occlusion?
Occlusion, otherwise the bite, is the relationship of the teeth of the upper jaw to the lower jaw, i.e. the upper and lower teeth, during the normal function of chewing and speaking. In dentistry, occlusion plays a key role in maintaining the health and function of the mouth, as well as in preventing serious health problems such as damage to the teeth, malocclusion, temporomandibular joint diseases and headaches.
Physiological and non-physiological aspects of occlusion
Correct occlusion should allow free movements of the lower jaw and the tongue, as well as an even distribution of force during chewing across all the teeth. In the case of incorrect occlusion, an imbalance of forces and a disproportionate loading of individual teeth can occur.
This condition can lead to toothache, abrasion of the teeth, and cracks and mobility. General symptoms can also appear in the patient, such as headaches, pain in the chewing muscles and pain in the muscles of the shoulder girdle, especially in the area of the neck and nape, as well as bruxism. In addition, clicks, crackling or jumping in the temporomandibular joint can occur. To realise the scale of the phenomenon of temporomandibular disorder (TMD), sources report that in the United States between 5 and 12% of the whole population suffer from TMD (about 16.5–40 million out of a population of 330 million people).
Causes of incorrect occlusion
Pathological occlusion can appear at any age and is a consequence of injuries and malocclusions, as well as of improper hygiene and dental care. Incorrect fillings, missing teeth and defects are of very great importance for occlusion. Also in the case of missing teeth, the correct fitting of prostheses is important. A huge, though underestimated, factor affecting occlusal disease is a stressful lifestyle, sometimes causing strong clenching of the teeth, the habitual biting of nails or objects such as a pen or pencil. From the patient's point of view it is important to understand how harmful these habits are and to eliminate them completely.
Diagnosis and treatment
The prognosis for a cure is favourable provided the changes are recognised early and comprehensive treatment is implemented – not only dental, but also in terms of physiotherapeutic rehabilitation of the facial muscles and psychotherapy. Treatment of occlusion can include the modification of an orthodontic appliance, the alignment of the teeth and even surgery of the temporomandibular joint.
Treatment of occlusal disease requires a detailed diagnosis. The basic element is the medical interview – the patient describes their sensations, symptoms and signs of occlusion disorders. The next step is the analysis of the state of the dentition based on the result of an X-ray and ultrasound of the temporomandibular joints and the masseter muscles. At this stage numerous functional examinations and anatomical impressions are also carried out.
Modern methods of treating occlusal dysfunctions
One of the methods enabling a full analysis of the patient's problems and the planning of comprehensive treatment is the Kois deprogrammer. This removable plate allows the doctor to assess the occlusal conditions, their quality, stability and correctness. The interpretation of the information obtained makes it possible to assess the degree of occlusion and the need for possible therapy.
Currently, axiographic examination leads the way in the diagnosis of occlusal disorders. A digital axiograph records the movements of the patient's lower jaw. The information obtained is used to design a special occlusal splint, allowing the reconstruction of the occlusal relationships in the future through the use of orthodontic, prosthetic, implantological or aesthetic-dentistry treatment.
An intraoral scanner is also useful. The program places the scanned and matched dental arches in a virtual articulator in order to carry out prosthetic work in dynamic articulation. For greater individualisation, a facebow measurement, the taking of functional bites and the entry of these values into the virtual articulator are recommended. The choice of methods and the duration of therapy are determined by the occlusal conditions and the state of the patient's temporomandibular joint. Abandoning treatment risks serious complications, a significant reduction in the comfort of life and even the loss of the dentition.
Splint therapy
There are three main types of splints used in the treatment of chewing-organ dysfunction:
- Relaxation splints – focused on pain relief and muscle relaxation (so-called myorelaxation). They are based on the principles of the reflex-biomechanical effect on the muscular-articular structures of the stomatognathic system. They are usually used for several weeks, most often at night.
- Repositioning splints – change the spatial position of the lower jaw and the articular disc in the temporomandibular joint in relation to the upper jaw. For round-the-clock use. Used in disorders of the spatial configuration of the temporomandibular joint.
- Stabilising splints – stabilise the lower jaw in the appropriate position in the joint.
The vicious circle of pain
Pain → increased muscle tension → fatigue → pain → increased muscle tension… This is a frequent problem of patients with occlusion disorders and TMD. The factor triggering pain causes rising tension in the chewing muscles, which in turn, overworked by constant work, produce lactic acid.
Lactic acid is produced in the tissues after intense physical effort, when the muscles do not receive enough oxygen during activity. We then deal with the "muscle soreness" familiar to us all. This in turn causes muscle pain, which is a stress-inducing factor for the body and leads to an involuntary increase in muscle tension in response to the pain stimulus.
Studies
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Occlusal interventions for managing temporomandibular disorders
Singh B. P., Singh N., Jayaraman S., Kirubakaran R., Joseph S., Muthu M. S., Jivnani H., Hua F. (2024) · Cochrane Database of Systematic Reviews · Cochrane systematic review
There is no certain evidence that routine occlusal adjustment or bite splints treat or prevent temporomandibular disorders in all patients. Management should be conservative, reversible and matched to the symptoms.
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Effect of occlusal splint on oxidative stress markers and psychological aspects of chronic temporomandibular pain: a randomized controlled trial
Alajbeg I. Z., Vrbanović E., Lapić I., Alajbeg I., Vuletić L. (2020) · Scientific Reports · randomised controlled trial
In patients with myofascial pain a stabilisation splint improved some symptoms, but the benefit has to be read against the natural variability of the complaint. A splint is a reversible tool, not a reason to rebuild the bite permanently.
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Long-term Effectiveness of Occlusal Splint Therapy Compared to Placebo in Patients with Chronic Temporomandibular Disorders
Vrbanović E., Alajbeg I. Z. (2019) · Acta Stomatologica Croatica · randomised placebo-controlled trial
Comparing a stabilisation splint with a placebo device showed that part of the improvement in pain and function may come from non-specific effects. This supports careful, stepwise treatment rather than promising one mechanical cause.