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Biter bort hodepinen    
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(English translation)
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Ny mirakelmetod mot huvudvärk
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Dr. David Hornbrook interviews Dr. James Boyd

Dental Practice Report, November 2001

Quick links to question topics:

What an NTI is

Definition of Bruxism 

NTI Contraindications

NTI and migraines

Who fabricates it

Traditional splint effect

NTI long term therapy

Success rate

Incentive for development

NTI vs. Deprogrammer

Occlusion philosophy

Factors for success

Q: The NTI appliance has gained much notoriety recently with your appearance on Good Morning America, however, this device been around for a couple of years. Still, many dentists arenít yet familiar with it. What is the NTI and what does it stand for?
     Boyd: The NTI is a tension suppression system that uses the bodyís natural reflex protection when being used during waking hours.   At night it prevents and reduces the muscular component of migraine, chronic headache and jaw disorders by preventing parafunctional contacting of the canine and molar teeth. It represents a major improvement over splints and night guards in treating and preventing clenching, grinding, bruxing, stiff neck, tooth sensitivity, tension headaches and TMD. 
      The device is a small, clear, taco shell-shaped appliance that fits over the upper two front teeth. Attached on the incisal edges of the taco shell is a bump or a bar that extends anteriorally and posteriorally to provide the point stop.
NTI stands for Nociceptive Trigeminal Inhibition. This is a technical way of saying the jaw opening is a reflex, and this device provides a way to suppress the elevating muscles of mastication.
     Clinicians are familiar with this concept. This is what an anterior deprogrammer or a Lucia jig is all about, however, the reason why the concept of the Lucia jig canít be used in a therapeutic, night-after-night modality is that if the mandible moves around, that is, it will ďdefeatĒ the jig by allowing fro a canine contact on the jig.  The NTI is the adaptation of the Lucia jig to provide for mandibular movements while still suppressing clenching intensity.
     The NTI provides for lower incisor contact to just prior to posterior occluding. This provides for ideal condylar seating or the best condyle location during closure.
     Itís a relatively simple concept. To be successful with the NTI, you donít have to take a lot of courses or learn a lot of theory. Itís based on established medical, physiologic activity.

Q: Who fabricates the NTI, the dentist or a laboratory?
     Boyd:  The NTI is a pre-fabricated matrix that eliminates  all of the laboratory work and most of the chairside procedures involved with splint fabrication and delivery..  Althought a dentist can  make an NTI type device from scratch, the prefabricated matrix  gets you 75% of the way to producing the final device. 
Thereís no need to take an impression or create models. A dentist could make this in his or her office without an NTI matrix and wouldnít be infringing upon NTI patents.  For those occlusal schemes that donít allow for the easy use of the NTI device, the website describes ow to easily make a custom NTI-type device in the office.

Q: What was your incentive to come up with the NTI?
     Boyd: It really was for my own use. I was a typical TMD patient who had a headache every day, all day long and I would occasionally have migraine headaches. Part of my symptoms involved a loud clicking joint, difficulty with opening and sometimes my jaw would get sore from chewing. I went through traditional TMD splint therapy and I was one of those people who seemed to get worse from the splint. Iíd wear it a few nights and then take it out for a night or two and then put it back in.

Q: The concepts of bruxism, TMD and clenching tend to have various definitions, and many practitioners relate parafunctional habits to the Pandoraís box of bruxism. How do you define bruxism and how do you get outside the box of splint therapy?
     Boyd: Physicians, dentists and the general public tend to think that bruxism means grinding of the teeth,  but thatís just the ďsecond halfĒ of the conditionís acutual activity.  You can have your jaw in a rest position and move it excursively back and forth and protrude and retrude. Thatís not bruxism, although the lateral pterygoids are functioning. You have to elevate the mandible first, which weíll define as clenching. Once those teeth come into contact or are occluding, due to the continual elevation of the mandible, onlyh then is grinding possible.
      At that moment, the lateral pterygoids are supposed to contract and reopen the mandible. Thatís a normal chewing or swallowing stroke. However, in bruxism,  the temporalis refuses to release and keeps these teeth occluding, or, ďin occlusionĒ as we say in dentistry.  The intensity of the elevation or the intensity of the perpetual clenching in the presence of the lateral pterygoid attempts at re-opening the mandible will dictate the grinding severity that results.
As the temporalis contracts more intensely, the teeth are occluded more tightly, thereby providing more resistance the lateral pterygoids. In other words, the grinding activity might become more severe. At the maximum degree of clenching, the jaw cantí move at all and the lateral pterygoids donít have a chance of any excursive activity. So, I look at bruxism as a function of clenching. The intensity of  clenching dictates the severity of the  grinding .
Dentistry seems to enter in mid-stream. Once the mandible has been elevated, the teeth are in contact. As the lateral pterygoids naturally attempt to reopen the mandible, they are met with opposing resistance provided by the temporalis, often resulting in the signs of symptoms of TMD,  and we address them. My approach to bruxism is to suppress the clenching intensity first, instead of trying to treat the results of lateral pterygoid activity.

Q: In the past, I had used a full occlusal splint, mounted in centric relation, to try to treat bruxism. Some clinicians feel this approach adds to the clenching. Do you believe thatís correct?
     Boyd: The temporalisí maximum contraction ability is with the teeth slightly apart. With some patients, when you provide a full-coverage splint thatís 2 mm thick and is mounted in centric relation, you may be providing the optimal ability for clenching intensity. And if the patient does this, he or she will have ideally stabilized jaw joints. Youíll address the TMJ condition and youíll be successful. 
The patient may still have headache or migraine pain or that may intensify. It wouldnít be apparent to the dentist, however. We tend to look below the cheekbone, and weíll have some success with those symptoms and never consider that perhaps the patientís increased temporal headache or migraine might be from the new ability to clench with more efficient intensity.

Q: Some clinicians feel the NTI device is essentially a deprogrammer. Is that a fair analogy? Also, how does it differ from the deprogrammer device used at the Pankey Institute or the Lucia jig?
     Boyd: The Pankey device is a prefabricated deprogrammer. A Lucia jig is a device you fabricate yourself. There isnít any disagreement over what these devices do. Theyíre designed to create ideal condylar seating and relaxation of musculature. However, the reason why theyíve never been incorporated into therapeutic practice, meaning letting the patient wear it every night, is that the mandible moves around.
     Letís look at one example of how this movement can affect the patient. If the mandible moves to the left, the lower right canine would have the ability to contact the deprogramming device. Canine contact allows for near maximum temporalis clenching. If the mandible demonstrates a left excursive movement with the right canine in contact, significant joint strain results. Thus, you may see a patient after four or five nights of using a deprogrammer who will say that the device works great, but then a week later they may be saying their joint is killing them.
Dentists reflexively would say, ďWe canít use that device long term because there could be joint strain.Ē No consideration is given to how that joint strain was created. The NTI is the response to that potential mandibular movement to prevent those joint strains.

Q: Are there any contraindications on using the NTI?
     Boyd: The primary contraindication of the NTI is in the presence of some degree of internal joint derangement that is not related to muscular parafunction. In fact, itís quite rare, but in those cases youíve got some degree of arthritic condition. An NTI device might be contraindicated even though the patientís muscular intensity is decreased. They still have the ability to move excursively, which might be straining for the joint. In those cases, a full-coverage splint is going to be a better option. 
     Other than that type of condition, there really arenít any contraindications for the NTI device. Unless, of course, the patient doesnít have incisors or if the dentist misuses the device by increasing the vertical dimension more than is required, which could create joint strain. Obviously, if doctors donít follow the protocol, they can do harm.

Q: So the NTI could be used as an alternative to long-term splint therapy?
     Boyd: Exactly. Iíve worn mine every night for 12 years now.  Some clinicians might say, ďWhat about the possibility of posterior supra eruption?Ē A posterior tooth that receives regular alveolar stimulation, which comes if the person chews food once or twice a day, has no opportunity for supra eruption. 
     In my case, none of my teeth has supra erupted since I began wearing the NTI. In fact, weíve never seen a true case of a posterior supra eruption with this device. However, clinicians sometimes mistakenly identify posterior supra eruption when a patientís mandible seats itself; that is, the condyle has seated into its musculo-skeletally stable position when it hadnít been before.  If  condyles  move posteriorally and superiorly, that reseating  creates more posterior and less anterior occluding, thus giving the illusion of posterior supraeruption.  However, both planes of occlusion have remained unchanged and it is a mandibular shift you are seeing.

Q: As youíre well aware, there is a lot of interest in and controversy surrounding occlusion today. Whatís your occlusal background and your philosophy regarding how these patients should be restored?
     Boyd: I look at the three components: musculature, bone and teeth. To me, the teeth, which are embedded in the bone, are along for the ride that the musculature gives it.
     I believe all dentists are trained in sound occlusal restorations in the musculo-skeletally stable condylar position. I like the term Dr. Jeff Okeson uses ďmusculo-skeletally stable.Ē We want the musculature to be in a normal, not a parafunctional or a dysfunctional, state. . 
     The way to achieve this state is to not give the musculature the opportunity to perform parafunctionally, with hypercontractions. Musculature can only do  that after the posterior or canine teeth are occluding.
Prior to initiating occlusal therapy, the NTI can provides for a normalized  musculature, thereby allowing for the optimal musculo-skeletally stable condylar position.  Centric relation  happens during a dynamic activity, while the condyle is being seated during active closure against resistance, which is the food between the teeth.  Itís not something that a dentist can dictate, but what normal musculature creates.    Dentistry can provide for normal musculature, thereby allowing for optimal condylar seating.  The  dentist will then be presented with an occlusal scheme that may or may not require restoration. 
     Once the jaw closes and the teeth are coming into contact, normally the jaw would start to reopen. Thatís what the lateral pterygoids are supposed to do. But when the muscles of elevation refuse to relax,the lateral pterygoids encounter resistance.  The presense of occlusal interferences causes an imbalance in the lateral pterygoids thereby causing changes in condylar position. So it makes sense to address the interferences to create a non-interfering occlusal scheme.
     Once those interferences are removed, the patient may have an optimally seated condyle and an optimal occlusal scheme. This doesnít mean that the parafunctional muscular activity is going to stop. You see that when you put in the ideal full-coverage splint mounted in centric relation. Patients still clench on those appliances. Iím not convinced that ideal occlusal schemes and ideally seated condyles will eliminate muscular hyperactivity. In fact, sometimes it just allows it to perpetuate.

Q: It seemed suddenly that the FDA approved the NTI for the prevention of medically diagnosed migraine pain. Does this mean that there is a relationship between clenching and migraine pain? Should dentists be treating migraines?
     Boyd: There is a relationship between migraine pain and clenching. For example, all migraine patients and  tension-type headaches patients exhibit pericranial tenderness. 
     In dentistry, we instinctively know what that means. In medicine, physicians donít routinely perform muscular palpation and typically donít inquire about or investigate pericranial tenderness. When the tension-type headache patients and migraine sufferers describe their pain, the physician interrogates and makes the diagnosis and referral. What they donít recognize is that pericranial tenderness is most likely the result of hyperactivity of the musculature. These patients, who are clenching nocturnally, have hyper-temporalis activity. This is an ingredient in what neurological scientists call kindling for migraine events. 
     The relationship to migraines is that these patients have high degrees of clenching while theyíre asleep. Dentists donít see this because many times the migraine patientís teeth look perfect. After all, they never grind their teeth because theyíre too busy clenching. Their jaw joints are fine because theyíre well supported during clenching and may even be in an ideal relationship. 
     All of this is not to suggest dentists should be diagnosing migraines. Thereís a huge difference between the diagnosis of migraines and the prevention of migraine pain. The diagnosis of a migraine requires that a physician perform a CAT scan, MRI, X-rays and examine blood work. 
     Once a patient has been diagnosed with migraine pain, meaning thereís nothing wrong with the patient objectively, the dentist can easily perform palpation to determine pericranial tenderness. Thatís when the NTI is used, as part of the protocol to prevent migraine pain.

Q: What are the success rates with the NTI in terms of eliminating bruxing, clenching and migraine pain? 
     Boyd: In the clinical trial data submitted to the FDA, 82% of medically diagnosed migraineurs (whom Iíll call ďprimary clenchersĒ) reported on average, a 77% reduction in their migraine frequency within the first eight weeks of wearing the NTI. 
     On the other hand, when we look at TMD or excursive activitiesóBruxismódentists have an even greater success rate because the patients theyíre treating with this device donít have as much clenching intensity. Dentists are a little surprised by the NTIís effectiveness. By the same token, they also see how quickly a patient can get worse if they donít adhere to proper protocol.
     I tell doctors: Donít think this is an easy, no-brainer thing to do and that all you have to do is pop it in the patientís mouth and they get better. You could make somebody a lot worse with this device, which is really one of the indications that itís effective. If used properly, though, itís quite effective.

Q: What are some of the critical factors that determine success with the NTI?
     Boyd: The most significant factor in achieving success with the NTI is the degree of vertical dimension of freeway space the device creates. 
     As that vertical dimension  increases we have to ask whether the condyle been significantly translated due to the presence of the device. I think of translation as leaving home base. During Parafunction,  you want the condyle as close to home base as possible at all times. If you have too much vertical dimension, that is, translation, you risk straining the jaw joint. If you donít have sufficient freeway space, you may be providing for canine of posterior occluding in excursive movement, thereby allowing for an increase in clenching intensity and/or joint strain. 
Letís say the patient has a 1 mm or 2 mm posterior disclusion or free way space with the NTI in place, but the moment they move excursively you get a posterior contact or a canine contact, therefore providing for the ability for clenching intensity while this joint has been translated to a degree.
     Itís the vertical dimension of freeway space created by the NTI that is fine-tuned. For example, as the patient moves excursively and you see a posterior contact with the NTI in place, it will be the most obvious presentation of an interference that you could ever get. That would be instant grounds for occlusal equilibration.

 

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