Tension-type headache patients, without signs or symptoms of jaw disorders (temporomandibular disorders, i.e., TMDs) contract their temporalis muscles (clench their jaws) during sleep, on average, 14 times more
intensely than asymptomatic controls (1).(M) (Slide 4)  Once the jaw is clenched, the supportive musculature of
the skull (trapezius) can assume a static contraction, resulting in chronic stiff and sore neck.

    Traditionally, an inter-occlusal mouthpiece ("splint", mouthguard, nightguard) is prescribed to "relax" the lateral pterygoid musculature by providing less resistance to side-to-side movement (a flat, smooth surface rather than the cusps of teeth) (3, green arrows).  Lateral Pterygoid muscles originate on the pterygoid plate of the sphenoid bone (the facial bone with houses the sinuses), and inserts at the condyle of the temporomandibular joint.  When chronically contracted (i.e., "dysfunctional") the lateral pterygoids can cause sinus symptoms (pain, pressure, but in the absence of disease) and/or signs and symptoms of TMD (a temporomandibular disorder: difficulty with oral function)

    If the patient's parafunctional habits are primarily side-to-side movements (lateral pterygoid activity), the splint reduces theresistance, therefore the intensity of the activity, thus reducing the strain on joint and facial structures (~50% of myofascial pain / TMD patients fall into this category).  If the patient's parafunctional habits include both a horizontal activity (lateral pterygoid) and vertical (temporalis), the result is "excursive clenching", where the patient forcibly clenches their jaw in an excursive position, allow for significant TMJ strain (2) regardless of the presence of the splint.  If the patient's parafunctional habits are more forceful in a purely vertical (temporalis) direction (4) (i.e., "primary clenching"), the splint provides an enhanced resistance, thereby allowing clenching intensity to increase (3, red arrows).  These patients typically may not complain of joint related signs or symptoms, but suffer from myofascial (headache) pain. (~1/3 of myofascial pain patients experience no relief from a splint, ~1/5 get worse) (Q) (Slide 7).
     An inter-occlusal device which provides for anterior incisor contact only (5), significantly reduces the contraction intensity of the temporalis', when compared to natural occlusion (6) (J), and also prevents the occlusal scheme scenarios necessary to allow for strain of the temporomandibular joint and facial structures (Slide 8) but onlyin a static position.

    Unfortunately,, in therapeutic practice, a device which contact the anterior incisors allows for lower canine contact on the device, which can cause significant TMJ strain and damage (7) (Slide 9).  By modifying the device to an Anterior Midline Point Stop (8), canine occluding is avoided, thereby making the AMPS more appropriate for therapeutic use.

      Further modification to maintain perpendicular incisal contact in protrusive and retrusive movements allows for suppression of parafunctional contraction intensity in all mandibular movements, thereby reducing and preventing TMJ and facial strain, and myofascial pain (10). (Slide 10)

    The N.T.I. Tension Suppression System method provides a preformed matrix which is readily adapted and retrofitted to the patient, and fulfills the criteria of an AMPS (9, 10), without adverse effects (Slide 11).
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