NTI vs Bite Splint

Thursday, February 22, 2007 - Shannon Johnson, DMD

(A letter from Lee and my response)

Dear Dawson Center,

I have attended 3 courses at the Dawson Center and I have a question that I need answered, perhaps from one of the teaching doctors (I believe my last instructor was Dr DuPont) or perhaps even still, you could direct me to information on your web site for my answer.

My question is whether or not it is advisable to make a NTI for patients (for nighttime use) over an indefinite (lifetime) period instead of using a Bite Splint.

I have heard conflicting reports as to whether or not this is advisable.

Thank you for your anticipated reply. You have answered other questions for me in the past and your help is greatly appreciated.

Sincerely,

Lee, DDS

Dear Lee,

Great question! The use of an anterior deprogrammer as definitive appliance therapy has become more common recently. There are a couple reasons:
0. Anterior deprogrammers (NTI, B-Splint, Kois appliance, and the like) allow for incredible muscle relaxation by eliminating posterior interferences.
0. There is a protective reflex that prohibits the body from placing too much pressure on the anterior teeth. Thus, the body reduces the forces applied to the teeth when only anterior teeth contact. EMG studies support this.
Anterior deprogrammers work best in patients who are chronic, severe clenchers/bruxers. Severe bruxers may not have complete resolution of muscle symptoms with a perfected occlusion/splint. Dr. Wilkerson has seen many of these patients. There is evidence that there are individuals who keep their teeth together at all times; not just when swallowing as we had been taught. These individuals, the chronic bruxers/clenchers have been treated with a definitive anterior deprogrammer to much success. Supra-eruption has not occurred as long as the patient leaves the appliance out a minimum of six-eight hours a day.

CAUTION: Anterior deprogrammer should NOT be used in someone with an internal disk derangement. Relaxation of the muscles results in the joints seating completely and this can be extremely painful for patients with disk derangements.

Sincerely,
Shannon Johnson, DMD
Academic Advisor

« Go Back

44 comments (Add your own)

1. Scott Poling wrote:: I have a 14 year old female patient that has a definite click on the left TMJ. The disc is disclocating but reducing on closure. The patient has no signs of bruxing and dose not complain of soreness in the mornings. I was thinking of doing a anterior deprogrammer to assess CR and her occlusion. I noticed a contraindication for joint derangements. Would the deprogrammer be appropriate in this situation?
March 26, 2007 @ 8:15 AM
2. Scott Poling, DDS wrote:: Addendum to the previous. The 14 y/o also has locked open.
March 26, 2007 @ 2:24 PM
3. Shannon Johnson, DMD wrote:: First lets address the splint question as if the patient will be wearing the appliance for an extended period of time...Anterior deprogrammers are best used in cases Piper Class 1, 2, and 5. For patients with displaced lateral or medial pole disks (Piper 3 and 4), the potential risk is that you may worsen the disk displacement as the condyle seats into the socket. In essence you may promote the condyle to slip further off the disk. Rather than an anterior deprogrammer, I would use a centric relation splint that is full coverage with even intestity centric contacts and a shallow anterior guidance.

Now lets address this concern as I believe you are asking...you want to use an anterior deprogrammer (lucia jig) to help take your bite record. Please let me know if this is a correct assumption. In this case, where the patient may be using a jig for only a few minutes, you can try it. Have the patient remove the jig immediately if she feels any discomfort in the joint area. Load test and verify centric as you would normally if she is comfortable.

This discussion can also lead into joint diagnosis. You want a clear and definitive joint diagnosis so that you can determine long term stability of her case. There is a significant difference in long term stability for Piper 3's versus Piper 4's. Have you diagnosed the joints?
April 4, 2007 @ 10:51 AM
4. Dr. Barry Glassman wrote:: I use anterior midpoint stop appliances (B splints and NTI's) DAILY and successfully with patients with internal derangements, including patients with disk displacements with reduction anteriorally, anteriomedially, and medially. The force vectors of the musculature are not posterior, and the decreased forces in the system created by the anterior contact often result in decreased pain and increased function. Us of JVA and jaw tracking evaluating joint vibrations and ROM has substanciated the subjective success in many cases.
June 20, 2007 @ 7:36 AM
5. Steven D Bender DDS wrote:: There is a growing body of evidence that would indicate the above assumptions to no longer be accurate. Many investigators have demonstrated a decrease in elevator activity utilizing the anterior midpoint stop appliance while full arch appliances with posterior tooth contact tend to allow for an increase in elevator activity during clenching. Allowing for condylar seating under limited loads is an ideal therapeutic outcome. A well constructed, full arch splint will also allow for condylar seating but according to reports, allow for increased load of the articulating surfaces in comparison to anterior stop appliances.
exquisite attention to fabrication, fit and adjustment is crucial for success with any appliance. This would also be true for the anterior stop style. Many failures or exacerbation of symptoms seen in our office are the result of poorly fabricated and/or adjusted appliance.
Hope this helps,
June 20, 2007 @ 11:16 AM
6. Jim McKee wrote:: This question is a great question because the situation is so common. The key to predictable treatment planning begins with diagnosing the condition of the TM joint. The TM joint will either be structurally intact, strucuturally altered at the lateral pole or structurally altered at the lateral pole and medial pole.

In patients who have structural alterations at both the lateral and medial pole, MRI imaging is the only diagnostic tool that will allow the dentist to predictably design on occlusal scheme on an occlusal appliance. In patients who present with discs that are in the 11:00 position in the medial pople, anterior mid point appliances have the potential to seat the condyle superiorly and cause additional forces on the already weakened attachment. Also, patients who present with large disks that are displaced medial (confirmed with MRI) are at an elevated risk for pain and skeletal distortions due to the potential for compromised blook flow to the joint. The patients I have seen who present with these cases have not fared well with the anterior midpoint appliances.

My personal experience is to use a full arch appliance is patients who have structural alterations at both the medial and lateral pole. In order to be effective, the appliance must be carefully relined to insure that there is no movement under occlusal pressure in any area of the appliance. Additionally, the appliance requires precise adjustment for even contacts in adapted centric posture/treatment position along with a very flat anterior guidance. While this design has worked extremely well for many dentists and patients over the years, there are some cases that this design will not help...most likely the two cases outlined above. Without an MRI, it is not possible to explain this to the patient before treatment begins.

MRI in conjunction with cone beam 3D imaging will give the necessary infromation to explain condyle size, condyle position, disc dise, disc position, the condition of the condylar marrow space. In today's world of comprehensive dentistry with treatment plans involving implants, esthetics, orthodontics, occlusal therapy, etc., TM joint imaging is a necessary diagnostic tool for the physician of the masticatory system.

Hope this helps

Jim
June 25, 2007 @ 11:18 PM
7. eric wrote:: Would a NTI or bite splint be good for me?
I was diagnosed with TMJ and i know its from grinding/stress. However i noticed that one side of my lower jaw is higher than the other whats wrong there. Is that realted to stress as well.

email me marinerseric@gmail.com
July 3, 2007 @ 5:31 PM
8. Jim McKee wrote:: Eric,

The best way to determine what occlujal appliance would be best for you is to diagnose the condition of the joints. If one side of your lower jaw is higher than the other side, then something had to cause the canted occlusal place. Possible causes would be genetics, altered eruption patterns, condylar breakdown, etc. Find a dentist who has been trained in diagnosing TMD from a lateral pole/medial pole perspective and go through the examination process. It will not only help you but also how you explain the problem to your patients.
Good luck

Jim
July 7, 2007 @ 11:25 PM
9. Steven D Bender DDS wrote:: How can an MRI help the dentist design an occlusal scheme on an appliance when the effect of the appliance has been shown to be independant of occlusal scheme (ie. equivicol results of a permissive or stabilization appliance compared to palatal only)? All that is known is that the elevator muscle activity will increase with more occlusal contacts, especialy in the posterior aspect.

There is no evidence that an anterior appliance will cause a progression of disc displacements. There is also NO evidence to support that an anterior disc displacement will compromise blood flow. Osteonecrosis of the condylar head is more likely to be a result of oxidative stresses from pathologic loading (Nitzan, Milam).
July 16, 2007 @ 11:21 AM
10. Jim Boyd, DDS wrote:: Jim mentioned: "The patients I have seen who present with these cases have not fared well with the anterior midpoint appliances"

The Gold Standard for the full-coverage splints described above is to provide for IMMEDIATE posterior disclusion upon excursion from CR. Why? Because that leaves *only* the incisor edges to be in contact with the splint, with the ideal contact being at the anterior midpoint, thereby minimizing the muscle contraction intensity that strains the joint and pathologically loads the disc.

The risk of appliance therapy is not the provision of incisal-only contact while in CR, but of the practitioner's poorly designed device. For example, it is not uncommon for a practitioner to mistakenly provide an anterior-midpoint appliance with a Discluding Element that provides excessive Vertical Dimension of Occluding. Doing so will create excessive condylar rotation during the occuding events, which can further complicate the condition. With NTIs, for example, the DE must *always* be adjusted and customized for the patient. I have seen many cases fail to respond when the practitioner simply removes the NTI from the box and "puts it in". Rather that abandon the concept, modifying the design to adhere to therapeutic protocol rectifies the matter.

Obviously, occlusal appliances themselves have no ability to seat the condyle superiorly and cause additional forces on the already weakened attachment. Vector forces generated by combined muscle groups do that, which only occurs during occluding events. The force vectors are then a function of the scheme of the occluding teeth and position of the condyle during the event.

With properly provided incisal edge contact, there is no ability to seat the condyle more superiorly and cause additional forces.
July 17, 2007 @ 9:29 AM
11. Lisa D. wrote:: I've noticed that with the past 6 months I have noticed jaw pain and slight headaches when I awake. I mentioned to my dentist and they noticed my teeth were starting to wear down on the bottom. I'm trying to get my insurance to cover a bite splint. They say it will not prevent me from clenching. My question is will the bite splint if worn at night help to relieve the headaches and muscle pain in my jaw. I'm trying to appeal my case to prevent further damage to my teeth. Thank you
August 11, 2007 @ 10:37 PM
12. Jim McKee wrote:: Steve,

From a techical perspective, elevator muscle activity may increase but the area of force distribution also increases. An anterior deprogrammer is approximately 10 square mm where a full arch appliance is approximately 100mm. Assuming the amount of muscle force generated will seat the condyles with either appliance, then the force will be distributed between the condyles and the appliance.

AVN was a controversial subject in the early 90s as those of us who have attended AES meetings can attest to with first hand experience. While Nitzan and Milam's excellent work show the effects of pathologic loading, it is extremely unlikely that this excesive loading would occur if the disc was intact at the medial pole. Today, marrow space disorders are a commonly accepted entity when talking to dentists/radiologists/etc who have not been influenced by the politics of the early 90s.

From a non-technical perspective, TM joint imaging is absolutely necessary to be able to inform the patient of the level of breakdown as well as the prognosis for treatment. MRI and cone-beam imaging offer the best imaging options at this time for suspected advanced joint problems.

Jim
August 14, 2007 @ 12:49 PM
13. Jim McKee wrote:: Lisa,

An appliance may help the pain that you are experiencing. The best way to determine if an applaince will help is to have an examination that will determine the condition of the TM joints and evaluate the way your teeth contact. After the exam, it will be more clear if an appliance will help as well as what type of applaince should be used.

Jim
August 14, 2007 @ 12:52 PM
14. Rache Smith wrote:: Short of picking up the phone book and calling every doctor in the country, is there a database of MDs trained in the Dawson method? How can I go about finding one near me?
September 10, 2007 @ 12:37 PM
15. Steven D Bender DDS wrote:: Jim,
As much respect as I have for you I have to point out that your statements lack evidentiary support. Numerous studies have shown that anterior only contact significantly reduces elevator muscle activity and therefore according to logistic modeling, reduces condylar loading (Baad-Hansen et al, Becker, Tarrantola et al,May et al). Full arch orthotics have shown an increase in elevator activity (Chandu, et al, Nishigawa, et al). Nitzan's work with articular pressures demonstrated a net increase in intra-capsular pressure while clenching on a full arch, posterior contact appliance (81.2% decrease from maximum voluntary = a net of 18.8% increase). Witter has shown over longitudinal prospective studies that a loss of posterior dentition is not a risk factor for TM joint disorders.
The key point to remember is that the density of periodontal mechanoreceptive fibers increases the more anterior in the arch making the central incisors the most innervated and therefore sensitive teeth to noxious stimuli. So, the location of force is pertinent as far as anterior-posterior but not surface area.

As to pathological loading of the disc; this is what CAUSES laxity of the tethering ligaments leading to discal location. The free radical production resultant from oxidative stresses causes breakdown of the synovial tissues resulting in a loss of integrity of the discal and other ligaments. The pathological loading is from nocturnal parafunctional activity where intensity, frequency and duration become the determining factors; not occlusal determinants. Osteonecrosis is not in doubt here; it is the etiology of such that seems to be debatable. With the abundance of collateral circulation to the condylar head, muscle impingement theories are somewhat naive.

Imaging can not tell us anything about prognosis. Again, the literature would seem to imply that the incidence of progression is unknown. In his latest text, Jeff Okeson reports that according to most literature on the subject, patients tend to become stable on there own or with very conservative therapy.
Hope this makes sense and is helpful,
Steve
September 12, 2007 @ 5:02 PM
16. tracy dobson wrote:: dear sir,

would love to know if one should risk using a kois appliance if having had no jaw problems ie pain, or teeth problems until a bad crown placed has caused bite to change.

do have odd bite pattern but am very worried after all the things done in the past year to try and fix my problems that this appliance may destabalize me to a worse state when the need for braces is probably the real answer.

very afraid to risk it???
help please
thanks

tracy
September 16, 2007 @ 12:38 PM
17. tracy dobson wrote:: dear sir,

would love to know if one should risk using a kois appliance if having had no jaw problems ie pain, or teeth problems until a bad crown placed has caused bite to change.

do have odd bite pattern but am very worried after all the things done in the past year to try and fix my problems that this appliance may destabalize me to a worse state when the need for braces is probably the real answer.

very afraid to risk it???
help please
thanks

tracy
September 16, 2007 @ 12:38 PM
18. Marvin Flick wrote:: My wife was advised by her dentist that she needed an NTI because she was grinding her teeth.She did however have an over bite. She had a clicking jaw at the time with no pain. When she started wearing the Nti she started having headaches so the dentist prescribed pain pills. The headaches went away within a couple of weeks, so she continued to wear the NTI as instructed, 24-7. Four months later she observed in the mirror that her teeth now matched in the front and within hours she yawned and her jaw dislocated. The MRI showed that she had an anteriorly dislocated and distored disc on the left, with no evidence of recapture. No she can not chew, her mouth will only open 20 cm, she has severe pain in the left ear and most of the time from the top of her head to her shoulder on the left side. I took her to Cleveland Clinic, no help. She is now seeing a different dentist who made her and full splint which he has adjusted at least 30 times in the past 9 months. This seems to help the pain some for short periods of time. Please advise if you can recommend anyone that can help. It appears my wife is maimed for life.
She blames the NTI, is she correct?
October 12, 2007 @ 8:36 AM
19. Jim Boyd, DDS wrote:: Marvin said:
"When she started wearing the Nti she started having headaches so the dentist prescribed pain pills".

The proper response would have been to identify the method in which your wife was "defeating" the NTI device. Provided properly, an NTI will either reduce muscle contaction intensity and joint strain/load (thereby reducing symptoms), or it will do *nothing* (thereby ruling out nocturnal parafunction as a contributory activity to the presenting condition).

"The headaches went away within a couple of weeks, so she continued to wear the NTI as instructed, 24-7."

It is physically impossible to wear an NTI "24-7". It's design and intent is to control nocturnal parafunction. Based on her initial response, there was/is an oversight in the therapeutic protocol.

"Four months later she observed in the mirror that her teeth now matched in the front and within hours she yawned and her jaw dislocated. The MRI showed that she had an anteriorly dislocated and distored disc on the left, with no evidence of recapture."

And those findings may have been there long, long before the initiation of therapy.

"Now she can not chew, her mouth will only open 20 cm, she has severe pain in the left ear and most of the time from the top of her head to her shoulder on the left side. It appears my wife is maimed for life...She blames the NTI, is she correct?"

A piece of plastic residing on the incisors, just by itself, cannot cause the above description. But a piece of plastic, improperly provided without an insight as to the nature of the pathologic activity of the on-going nocturnal parafunction, can intensify and complicate signs and symptoms (that's a line from my lectures, BTW).

Is she maimed for life? No.
Does she require a re-evaluation and assessment of her parafunctional activity? Yes.
October 12, 2007 @ 1:03 PM
20. Jim McKee wrote:: Steve,

Sorry for the long delay in responding...I also have great respect for you and your work however, we both know that the literature in the field of TMD/occlusion is incomplete at best and misleading at worst. I don't disagree that anterior appliances decrease muscle activity and they can be very beneficial in many patients. However, the condition of the condyle has to have some pertince to the discussion. While imaging cannot predict the future, it can lead to an important discussion regarding the condition of the tissue that we are treating. If an orthopedic surgeon did not image the knee and treated by doing what other claim is effective, the treatment would be judged below the standard of care. It really should be no difference for the TM joint. While conservative therapy is the goal for all patients, some require a surgical intervention if conservative therapy has not been successful. The usual surgical patient has either pain that is not manageable or skeletal distorations.

In terms of progression, I think it is a new ball game today. We are seeing more TM joint damage with greater severity at earlier ages. Imaging confirms this beyond any doubt. Condyle/fossa ratios, ramus lengths, condylar surface areas as well as other factors can all be analyzed today and confirm that growth disorders do indeed occur. These young patients ( almost always young women) need intervention due to the skeletal distortion that has occurred. These cases certainly are not all AVN cases...although AVN of the mandibular condyle is a regularly accepted entity today. I'm assuming you meant disc impingement as opposed to muscle impingement but if enough MRIs are reviewed, there is no doubt that AVN will be present.

Finally, the question of what causes disc derangements is really at the heart of the matter. I must admit that I have changed my thinking on this matter over the years. I initially thought that occlusal forces (function/parafunction or any other occlusal forces) caued the majority of disc problems. Currently my thougts are that disc problems are caused by traumatic incidents...it may take one incident if it is severe enough or more likely a cumulative effect of several traumatic events. There are too many young patients who have not have enough time to parafunction to the extent necessary to tear the ligaments.

To be fair, the patient base that we see is probably different. I know that you see predominantly pain patients which is different type of patient than the patients I typically see. My practice is about 1/3 TMD/occlusal problems and 2/3 restortative/esthetic cases. The TMD patients I see are almost exclusively referred by dentists who suspect a joint problem. I don't see too many patients who present with more medically based problems. Enjoyng the discussion...looking forward to a longer talk together at the AES meeting in February.

Jim
October 16, 2007 @ 9:43 PM
21. Jim wrote:: Dear Marvin,

I'm sorry to hear about the problems your wife is having. A complete TM joint exam would help to gain a more clear understanding of the problem. Depending on the results of the exam, TM joint imaging may be indicated. If so, a MRI and cone beam imaging offers excellent information that can help to diagnose the condition and lead to treatment decisikons.

Good luck,

Jim
October 16, 2007 @ 9:47 PM
22. Jim McKee wrote:: Dear Tracy,

My advice would be the same advice as Marvin...have a complete TM/occlusal exam and you'll have more information to make a decision.

Good luck

Jim
October 16, 2007 @ 9:49 PM
23. Steven D Bender DDS wrote:: Jim,
Your points are well taken. I would propose though, that children do in fact brux, reportedly more so than adults, to enough of an extent as to incur damage to the articular structures via oxidative stress injury. Due to the child's exaggerated time in stage 2 and REM sleep as compared to the adult, there is more opportunity for bruxism events. It has also been noted that children are much harder to arouse from the sleep stages as compared to adults. This could lead to a more vigorous bruxing event. One can simply not discount the beautiful work of Chuck Milam in this area.

I too enjoy the discussion, especialy with a man of such insight and integrety!
Steve
October 19, 2007 @ 4:13 PM
24. scott ma, dds wrote:: Dear Mr. Marvin Flick:
It appears that your wife'condition is long standing as limited mouth opening. The first thing you can do is to find a practioner who is skillful in manual reduction of displaced disk. For long time limited mouth opening, it usually goes along muscle spasm. Therefore, a cool spray of masseter muscle may facilitate downward distraction of mandible. Once the mandible is depressed downward, move the mandible to right side. If disc is successfully reduced, a loud pop sound can be heard and normal range of mouth opening can be restored. I have treated one patient who had 3mm mouth opening resuling from disc displcament. However, her contiotion was only 3 or 4 weeks. Your wife's contion appears much longer. If the disc can not be reduced manually, a well made cr occlusal appliance or sugical intervention is warrented. hope this helps
sincerely
scott ma,dds
November 11, 2007 @ 10:38 PM
25. Vanicha P wrote:: Dear Doctor,
I would like to share my experience and ask some questions regarding full coverage occlusal splint.
Some of my patients with DDR and intermittent locking got joint lock or more uncomfortable after wearing a stabilization splint. How this could happen? Could somebody explain the TMJ mechanics on this topic. Thank you.
P Vanicha
December 1, 2007 @ 6:00 AM
26. Karen Hicks wrote:: I am a lifetime clencher. I used an NTI in my early twenties. I have used a top mouth guard for the last several years. About 8-9 months ago I woke up with severe jaw pain and limited motion. I can open my jaw about 28 mm. I went to a neurologist to rule out any other issues. I went to a "TMJ" specialist and he said to get physical therapy and go back to wearing the NTI. I still had a great deal of pain with the NTI - so I went to get a second opinion from a maxofaccial(sp?) surgeon. He said that I have significant arthritic degeneration in both jaw joints and they are both dislocated. I did have an s-ray as well as an MRI. One side has already created its' own scar tissue - the other side has not. He said that he would not wear the NTI for even a day because it would create more of a problem because of the dislocation. I spoke to the original "TMJ" specialist and he said - "different doctor, different opinion" - although this NTI was made without the benefits of an MRI. Although the surgeon did recommend surgery for one side of the jaw - he did recommend getting a second opinion and seeking Physical Therapy and perhaps acupuncture. I have done both of these and have seen little improvement.I am 38 years old and this affects every moment of my life. Any opinions on whether the NTI should not be worn with a condition like mine?
January 3, 2008 @ 12:31 PM
27. Steven D Bender DDS wrote:: Karen,
To be therapeutic, any intra-oral appliance must be well thought out designed, fabricated, and adjusted precisely for your particular needs. If the NTI is causing your pain and symptoms to worsen, it likely does not meet the appropriate criteria to be therapeutic. if properly made and adjusted, the NTI can significantly reduce the pressures exerted on your jaw joints and muscles during night-time clenching.
I suggest finding a doctor who is experienced with NTI therapy and have them evaluate your current appliance. In most cases, fine tuning the appliance can make a huge difference in the results!
Good luck,
Steve
January 16, 2008 @ 11:56 AM
28. Maria Longo, DMD wrote:: Karen,
I agree with Dr. Bender. I find that 80% or more of occlusal or splint therapy offered in the USA is less than adequate. We are supposed to get as close to Centric Relation, or the place where the jaw are seated properly along with the joint (healthy or not) and the base of the skull. It sometimes requires numerous follow-up visits to "chase" the jaw and muscles to their proper place. This means we have to fine tune the appliance until there are no changes in the alignment and the joints, bones and muscles are all "happy".
January 17, 2008 @ 7:59 PM
29. wrote:: I have both TMJ discs displaced. The left without reduction and the right with. I had a full coverage splint adjusted many times with little improvement of symptoms. The ear pain is a horror. Recently it was suggested I try the NTI splint. I am confused by what I read (not to be used in patients with ineternal derangements). Will this help? I certainly don't want to make it worse.

Karen
January 29, 2008 @ 5:53 PM
30. Joe Patient wrote:: After reading many insightful posts here, I am downright disgusted with my dentist and am finding another one. My dentist recommended I wear one, had an assistant make it, and was handed a cheesy brochure and ushered out. The dentist did not participate in my treatment beyond suggesting the device and billing me.

I wore the device a few days before noticing my jaw was misaligning and I had trouble talking withing hitting my teeth together due to my lower jaw starting to move over to the left from where it used to be. It has since moved back. I threw out the NTI.

Now I just need to find a good dentist, it's my fault for not doing my homework on this until now, but I never needed to until now.

Joe
February 6, 2008 @ 3:48 AM
31. Lawrence Gottesman, DDS wrote:: Dear Dr. Shannon:

I am currently undergoing a rather extensive literary review concerning the function of mechanoreceptors in anterior and posterior teeth and their role in neuromuscular coordination.

It seems that there is a misinterpretation as to the effects of anterior tooth stimulation and the jaw opening reflex.

Firstly, the jaw opening reflex refers specifically to the transient reflex exchanges between muscle groups as influenced and modulated by tooth contact in the anterior region, the central incisors having a dominant role in only an inhibitory contribution over the elevator muscles. The information related to this reflex is mostly predicated on animal species with some recent human studies. The actual masticatory reflex is considered to be under the auspices of a central pattern generator (CPG) as a means of regulating or coordinating multiple tasks between several systems as an automatic phenomenon that can be modulated by various mechanoreceptive or cognitive stimuli.

Secondly, this reflex is signaled by activation of high threshold, rapidly adapting mechanoreceptors responding to directional tensive stimuli. They respond more to high phasic forces in order to rapidly unload the teeth as a protective mechanism.

Therefore, horizontal forces trigger the receptors located closer to the fulcrum area of the PDL. The low threshold, slowly adapting receptors are far more abundant and located in the apical region of anterior teeth. They respond to both phasic and sustained stimuli, however, their stimulation is excitatory in influencing muscle closure activation.

Thirdly, these excitatory and inhibitory reflexes occur in milliseconds with respect to the activation of the jaw closure inhibitory reflex. Subsequent to the inhibitory phase, there is a reinstitution of the excitatory mechanism.

Fourthly, molars have mostly excitatory jaw closure mechanoreceptor initiative and have a large predominance of low threshold mechanoreceptors responding mostly to axial compressive stimuli.

The abundance of tooth receptors descend from centrals to molars.

In light of this information, the NTI appliance or any appliance with a mini-anterior platform, which tends to axialize forces over the over lower centrals (also involved in the same reflex response as upper central incisors)may actually initiate some excitatory activitity of the elevator group, but without co-activation of the molar mechanoreceptors because they are out of occlusion. Aditionally, to my knowledge, there have been no studies on anterior deprogrammers, like the NTI, which isolate localization over the 2-4 anterior teeth and their opposing counterparts and the sustained effect load has on anterior mechanoreceptor activation. I think this makes the B splint a better choice because it does not load the anterior teeth selectively.

The NTI may actually work becauase it initiates an excitatory effect over closure muscles, like the Kois appliance, and allows the condyles to seat without interference from molars or their mechanoreceptors. In addition, the Kois appliance has an added benefit (in my opinion) of activating palatal soft tissue (which also contains mechanoreceptors) as a stimuli for decreasing muscle closure excitation.

I would also like to comment on appliances and intraarticular derangements. If there has been loss of normal integrity of the condyle disk assembly, whether congenital or traumatic, this is an internal derangement! It seems we save the use of this term for painful intraarticular sequelae. I think what we need is a classification of derangements to include the painful and nonpainful joints along with the other obvious parameters.

With respect to treating a painful intraarticular problem, if an anterior minimal incisal table appliance won't help, don't expect a splint with universal contacts to provide a greater benefit because it coactivates molar mechanoreceptors.

Finally, with respect to sleep bruxism, I have found that less damage occurs with an appliance similar to the B splint and the Kois as a hybrid between the two. Cuspid protection does not apply to sleep bruxism. Bruxism is not under the control of a conscious state. Most sleep bruxers continue to brux even in the appliance.

Thanks for the opportunity to share my knowledge with the Dawson folks...say HI to Pete and the rest of the gang for me.

Sincerely,

Larry Gottesman, DDS
March 3, 2008 @ 5:01 PM
32. Steven D Bender DDS wrote:: Larry,

Thank you for you very insightful comments. As to the periodontal mechanoreceptors: I'm sure you have seen the papers that indicate the postulate of there only being a single type of receptor (low threshold) that react with varying rates depending on the stimulus and angulation of such stimulus.

Another fact to rememb