What is Muscle Deprogramming?

A patient presents with bruxism or temporomandibular disorder.

It is important to consider muscle deprogramming of masticatory muscles in treatment planning. Pain in patients with temporomandibular disorder is of myofascial origin. Specifically, myofascial pain is from strained muscles putting pressure on bone. When muscle pain causes discomfort, patient quality of life decreases. Prior to starting restorative and full mouth rehabilitation cases, the treating doctor should evaluate patients for bruxism. By developing an understanding of the role that muscles play in restorative durability, the doctor can predict successful outcomes for the patient.

Often a dentist restores a patient’s dentition first and later fabricates an occlusal guard for use at night time. However, in this scenario, muscles remain programmed in their constrained states. As soon as the patient becomes non-compliant with occlusal guard use, he or she bruxes through restorations and fractures ceramic. Providers should, instead, learn to deprogram the muscles first so as to adjust how they mold around the skeleton. The temporomandibular joint is the most dynamic joint; if we support the muscles in a relaxed state, the bone will respond to the new pressures on it and will remodel.

Muscle deprogramming refers to resetting the muscles to their most basic state.

The neuromuscular theory suggests that parafunctional habits are the result of a dysfunctional masticatory muscle system. This contrasts with the longer-standing gnathologic theory, which is an observational theory that emphasizes condylar position and ignores musculature.

Gnathologic theory gave birth to the terms centric relation, centric occlusion, and maximum intercuspation. According to this theory, the jaw is balanced and stable when centric occlusion equals maximum intercuspation. When parafunctional habits result in a loss of vertical dimension, the most reproducible position is centric relation. For a reconstructive case, the jaw is manipulated into centric relation and the height of restorations is set to that position.

The gnathologic camp created one of the first and more controversial muscle deprogramming techniques. The Nociceptive Trigeminal Inhibitor (NTI) is a splint that isolates all occlusion to the maxillary and mandibular anterior teeth. Disoccluding the posterior teeth disallows bruxing, and a patient won’t brux on anterior teeth for fear of breaking them. However, wearing this long term can cause an anterior open bite and posterior supra-eruption.

The neuromuscular theory postulates that muscles fight back when the jaw moves into an “unnatural” position. This theory disregards the position of the condyle. One type of neuromuscular deprogrammer is a transcutaneous electrical nerve stimulator (TENS) unit. A variety of medical settings use TENS units.

Using a TENS Unit

In the dental setting, TENS units attach to muscles of mastication to overload these muscles with stimulus. As a result, myofascial pain and bruxism improve. The patient undergoes a series of deprogramming states. Deprogrammed muscles fire into an average spot where the electric current puts a patient into maximum intercuspation. This is the patient’s new baseline. The dentist takes a bite registration at the baseline, where maximum intercuspation equals centric occlusion. Occlusion is set to this baseline in a full-mouth reconstruction case. The dentist may also fabricate an occlusal guard at this stage.

Another means of muscle deprogramming is blocking their contractions entirely. Delivery of neurotoxin to the muscles of mastication shrinks hypertrophic, overused muscles. Botulinum toxin binds at the presynaptic cholinergic nerve terminal and inhibits the release of acetylcholine. This paralyzes the muscle, so it no longer fires. Muscle pain diminishes because the patient is unable to brux. In a full mouth reconstructive case with Botox administration, the provider uses bilateral manipulation to approximate a patient’s centric relation. The condyle must be manually moved into the anterior-superior position when muscles are removed from the equation. According to the gnathologic theory, occlusion is set to that new condylar position.

Takeaway

The field in dentistry that deals with parafunctional habits such as bruxism and their relation to occlusion is still rapidly expanding. The neuromuscular and gnathologic camps  disagree about how to best increase vertical dimension. The fact that there is controversy in theories suggests that there is much more to understand, especially when there have been successful outcomes in both. New therapies with an understanding of historical premise are necessary to advance this critical topic. Gone are the days where bruxism = night guard.