-D- CONSEQUENCES: TEMPORO MANDIBULAR DISORDERS (TMD)
Fig. D 13a,b: Proposition of a new classiﬁcation of mastication cycles, by the authors, in the frontal plane. (Replicator®, Sirognathograph®, Zebris®.)The C1 cycles, recorded are physiological. The C2, 3, 4 result from occlusal sub-guidance, responsible for the deﬁciency of underlying proprioceptive information and the deformation of the cycles (Johnsen SE and Trulsson M. 2003a p1486). Their shape is modiﬁable by addition in order to restore and balance the information transmitted to the periodontal mechano-receptors, which allows the cancellation of the protective mechanisms and immediate restoration of the shape and the optimal efﬁciency of the cycles. For C5 cycles in over-guidance, the shape can be restored by orthodontics or subtraction. C7 cycles require complete occlusal rehabilitation of the two arches by addition. C9 cycles result from various mechanical joint interference. They can be partially, totally or not at all improved by addition. But the reversible addition test must be done to ﬁnd out. Youtube:https://youtu.be/Heo8c8KM4WY
TMD From Occlusal Origin: Therapeutic Principles
Fig. D 14: Young woman, dental practitioner, with a past of orthodontist treatment. The right side is the dominant chewing side (optimal guidances and breadth cycle ).The left side is a rarely used (misguidance, vertical cycle and TMJ noise).
When the choice is possible, it’s alway the side with the best coordinated guidances that becomes the preferred chewing side.
Left side is balanced in CPO either centrifugal or centripetal movement have a Canine Protected Occlusion (ideal for a gnathologist, but unfortunately the human model don’t works like that)…
In the seventies, Temporo-Mandibular-Disorders (T.M.D.) have been very often imputed to occlusion. Two currents of thought were then opposed:
An occlusal approach (Rosenthal 1980) and a psycho-physiologic approach (Laskin 1969,1977).
The occlusal procedures for treat TMD, according to the gnathologic model, have resulted in poor results with very high rate of failure: 64%(Moloney et Howard 1986), 45% (Palla 1996), 59% (Le Bell et Kirkeskari) and 75% (Molhin et al 2004 ).
Today a multifactorial etiology is admitted for TMD, and occlusal etiology is not more regarded as their only primary factor (Rinchuse et al 2007). Its rate of involvement would be situated between 10 and 20% (Mac Namara et al 1995).
Otherwise the evidence-based view on occlusion and TMD does not argue or conclude that occlusion has no relevance to TMD (Rinchuse 2007).
Height literature review reported by Rinchuse (2006) even conclude “that occlusion and orthodontic treatment do not cause TMD, and occlusal adjustments are not recommended for the initial treatment of TMD”.
Which credibility have these contradictory data, when at the same time the success rate don’t have been noticeably improved.
It’s essential to question ourself on the reason of a so hight failure rates (reported above), going with doubts and controversial opinions:
- All of the clinical parameters have been them well assessed?
- Is the appropriate treatment?
- Are there other alternative therapies?
The various as possible etiologies, of TMD have been assessed, but regarding occlusion, the numerous studies realized have been linked to the classical CPO model (canine protected occlusion) which“ is equivocal and unsupported by the evidence-based literature” (Rinchuse 2007), because it do not takes into account chewing function and swallowing, the two originator functions of the manducatory tract, and because it takes into account, only a very reduced part of the real functional envelope and in reverse orientation. It is then not feasible to jump to conclusions, with their results, and the assertions claiming that occlusion is not involved in TMD, are not relevant.
In the human body context, when an organ is injured, the restoration of physiology of its anatomical structures, often necessary and sufficient is a requirement for this organ to function again.
In the TMD context, one can then well understand why, pain sedation and healing, could not be obtained, if the functional physiology of masticatory tract is not restored.
The relationship between occlusion and TMD must not be, a priori, questioned, but rather the functioning model and the occlusal procedures used.
To find relevant data on the real percentage of TMD resulting from occlusal origin, it’s essential to take into account the natural model founded on deglutition and mastication.
There is a kinetic and anatomic close relation between occlusal faces and TMJ, that has been established during growth.
Furthermore, in child, we have seen that anomalous occlusal relations (class 2, Class 3…) are related to abnormalities of tongue posture (Deffez et al 1995, Bonnet 1992, 93,99) and are co-responsible for disorders in facial growth and progressive dysmorphoses, like defect in vertical, transversal and anterior growth, possibly resulting in anomalies of mandible posture. If the growth is not reoriented early (Bonnet 2010), these dysmorphoses will worsen and their secondary treatment possibly requiring orthognathic surgery.
In the adult, articular anatomy and occlusal guidances will maintain their coordination by a progressive adaptation (Mongini, 1972,75,77). The functional coordination of articular surfaces is maintained by the constant postural tone of the elevator muscles. But occlusal anatomy of teeth can be progressively worn out (with TMD or not), or destroyed by teeth loss.
The objective of occlusal reconstruction (from a restored DVO and a MIO fitted with swallowing) is getting new contacts and dental guidances functional, coordinated with the envelope limit TMJ movements in the state adaptation wear where the joints at the time of reconstruction are. Because TMJ is then the only memory of the functional kinetics of the lost occlusal faces.
When an harmonious coordination of guidance is restored between occlusal anatomy and TMJ, manducatory tract find again its physiologic functioning, optimal cycles pattern is spontaneously reestablished without training. Then pains and articular noises disappear (provided there is no lesion of disc structure and that stress factors were under control).
Fig. D 15: The patient is a man, dental practitioner.
The closure path and M.IO. previously have been balanced. Functional misguidances are present on the two sides, with adaptive modes on each side. There is not any possibility to choose the best side, but only the less worst !
Clinical Results : Consequences
Similar results are constantly observed. The restoration of the functional guidances on the first molars is generally sufficient to find again the cycle breadth. Occasionally it’s necessary to ad second bicuspids. The next teeth, are then progressively integrated to the restored functional scheme. To only reestablish the bicuspids don’t allows to reach the maximum breadth of a cycle, because their guiding potential is small-scaled. If first molars are missing, coordinated guidances between second molar and bicuspids are generally sufficient.
These statements are not conceptual, but the outcome of clinical treatments, regularly obtained for more than 15 years of practice, and during 40 clinical trainings and workshops on occlusion procedures. If in private practice, the numerous results have not been quantified, it’s different for occlusal clinical training, because the majority of the cases have been documented or movies have been realized.
On a period of 12 years, 40 clinical training on occlusion of 2 days, have been organized with an average of 10 participants.
Following an analysis of models, the closure path each participant has been checked and balanced, if necessary, with the protocol of anterior jig, still described.
From two to five patients with under-guidances have then been selected for composite-up tests. So a minimum average of 3 for each training, representing at least 120 patients.
Positive results have been obtained in more than 90% of the cases.
These outcomes include in diverse ways: immediate improvements of cycles breadth allowing to restore chewing function and occlusal comfort, increasing amplitude of mandibular movements (opening, laterality…), sedation of muscles pain and headaches, reduction and/or immediate disappearing of TMJ noises…
Moreover, these tests allow to detect almost immediately, patients, not relevant for occlusal therapy, and to early reorient them, without any occlusal mutilation, because the tests have been realized by reversible composite-up.
All these results have progressively transformed our doubts in certitudes on the functional irrelevancy of the classical model of occlusion and on the limited relevance of the studies only referred to it.
Fig. D 16
Fig. D 17
New Modified Protocol
Within the multifactorial etiology of the TMD, the restoration of the natural functioning model of occlusion, has been proposed as an etiologic treatment for the share of TM disorders from dental origine. Unlike the conventional protocol of treatment that is to wear a bite plane to change temporary occlusion and then apply the RC and CPO concepts to balance the occlusion. This protocol has been modified. During the initial occlusal analysis, if a functional malocclusion is observed, reversible etiological tests are made immediately after the verification of the closing path and prior to any other treatment. They consist in, composite addition, aiming to restore balanced chewing guidances. If symptoms improve immediately after the restoration of physiological cycles, the share of occlusal etiology is considered decisive. If these tests are not followed by any improvement, the patient can be rapidly redirected to assess other possible etiologies of dysfunction.
This etiologic approach has allowed to note more clinical success that it was planed, when compared to the hight failure rate resulting from the use of classical concepts.
More over that procedure has allowed to much quicken the treatment, when patients had an occlusal etiology. For more than 15 years, it is become our clinical procedure and, in these conditions, the necessity to wear a bite plane has decreased of around 90%
Considering the high level of clinical success and the immediate recurrences, when the composite-up came away suddenly, it become obvious, that restoration of occlusal functional physiology was the etiologic treatment of TMD resulting from, dyskinetics between teeth and TMJ.
These results have not been quantified in private practice, because it was difficult and they were unexpected. But they are similar to those of workshops evaluated above, in the prior chapter.
It remains necessary to measure more precisely their results, in prospective studies, and to determine the actual share they represent in the multifactorial etiology of TMD.
The patient who consults for temporomandibular disorders is a worried patient because he suffers. When the restoration of functional dental equilibrium allows the relief of muscle contractures, responsible for pain, it has an immediate positive impact on confidence, the level of stress and its behavioral consequences. That is why it is important to relieve quickly.
This is one of the reasons that led us to practice as soon as possible reversible etiological test, even delaying further tests which were then lose their indication when the tests are positive (often). In fact we have never had to remove these composite additions because they always improved patient comfort, although sometimes the presence of structural lesions of the TMJ did not permit the disappearance of articular noises, as confirmed by MRI applied secondarily, in case of failure.
You will find below the general summary of the processing steps. This general approach is applicable to TMD as simple additions, but depending on the severity of the case, they should be strictly followed or may be very reduced.
POSITIVE OCCLUSAL BALANCING : Diagnosis and Clinical Tests
Treatment principles outlined below apply to all dental specialties, surgical, orthodontics, implant, prosthetic, postural, behavioral, concerned with the establishment or restoration of the functional model of the manducatory tract. Non mutilating techniques occlusal equilibration are recommended: by additions on natural teeth and additions-subtractions to the prosthetic restorations.
– General Examination
Visual examination of the overall balance, gait (postural problems, traumatic history), the morphological type and appreciation of the psychological profile (behavioral aggravating factors). According to the case, some general pathologies (eg postural) should be treated before, simultaneously or after the occlusal treatment.
– Review Local:
Height of the lower floor of the face, Facial symmetry and facial musculature,
General condition, dental and periodontal
Opening and closing movements,
Occlusal relationship and occlusion,
Position and form of the tongue,
Control chewing function,
Possible muscle palpation.
– Analysis of Models
The analysis casts must precede the therapeutic step. The wear facets, dental guidances, over-guidances and under-guidances, occlusal relationships, any misalignments will be identified, recorded and confronted the clinical examination. The manual coaptation casts often permits the simulation of chewing movements and appreciation guidances.
– Clinical Protocol
The objective is to verify and restore, if necessary, the functional equilibrium of swallowing and chewing. It is undertaken prior to a prosthetic treatment and when to the clinical examination indicates a possible involvement of the occlusion in TM Disorders (in the latter case, must be limited to initially test by addition fully reversible).
FIRST STAGE: Check the Vertical Dimension, the Intermaxillary Relationship and swallowing occlusion protocol: anterior jig + posture of the tongue. This step must precede chewing function balancing.
SECOND STAGE: Rehabilitation chewing guidances. Human occlusal anatomy was selected to work and have maximum efficiency in class 1.
Reports Class 1
Rebuilding of cusps in under-guidance by composite-up, if the occlusal anatomy of the antagonist and its location on the occlusal curves is optimal. Otherwise first prepare the anatomy antagonist in compliance curves. The cusps are rebuilt at the same location. It is easy.
Reports Class 2
Class 2 and more in the partial class 2, cycle-in guidances are reduced and cycle-out guidances nonexistent. The simplest solution is to change the mandibular occlusal anatomy, by creating an artificial antagonistic cusp in the internal side of the cusp disto-buccal maxilla. Cusp having a support buccal cycle-in and a cycle-out table on its inner side, installs guidances generally sufficient to restore the kinetics of chewing cycles.
Reports Class 3
Classes 3 have very few pathologies. Choice of surfaces to be rebuilt, allowing the restoration of cycle-in and cycle-out and comfort of chewing.
Inverted occlusions with 8 cycles.
Reconforming guidance surfaces by adding-subtracting by applying the same clinical principles.
Open bite secondary to lingual dyskinesia
Sometimes there is only one pair of posterior teeth in functional occlusion on each side. The principle of treatment is to restore the function by adding one or two additional teeth pairs on either side (which depends on the symmetry or not the gap). Never completely close a gap without lingual rehabilitation.
Clinical situations are manifold. All complex cases, residual dysmorphoses, open bites, overhang, surgical suites will be treated by applying the same principles customized depending on the clinical situation. Do not hesitate to install relay functions as a cycle-int on a tooth and a cycle-out on its neighbor and distribute guides on several posterior teeth.
The usual treatment of temporomandibular disorders in dental practice through the implementation and wearing an occlusal splint
Note: Occlusal splints ) are devices, which placed maxillary or mandibular arch transiently modify the maximum intercuspation (Unger 1995.2003), with the objective:
➤ Or to obtain the relief of muscle spasms before performing occlusal equilibration, for neuromuscular reconditioning splints, they have often flat planes that do not guide the mandible in a particular position (Unger and Brocard, 1996), they are permissive. Anterior deprogrammer like bite planes and anterior jigs belong to this family.
➤ Or for a repositioning of the articular disc. They are non-permissive:
-Using The mandibular repositioning splints, deeply indented in a therapeutic or other propulsion position (Brocard and Unger, 1996).
-Using joint decompression splints.
➤ Night guard splints are dedicated to the protection of the arcades from the consequences of bruxism. Generally flat plane splint are used. But the AJC (Anterior Splint Jig) can be used with remarkable efficiency.
➤ Other families exist, such as hydrostatic or rubber splints
But the interposition of an occlusal splint during painful dysfunctions give unpredictable results:
- Either it improves the painful symptoms
- Either it has no effect
- Or it worsens the painful symptoms
These inconsistent results certainly depend, in part, the etiology of pain that may have no relationship with the occlusion, especially when the port of the splint has no effect. However when there is an improvement or a deterioration, there is a certain relationship with the occlusion. The inconsistency of the results is then to be related to the type of splint selected based diagnosis and occlusal concept applied to balance it. For often the secondary modification of occlusal contacts and guides is able to modify the painful symptoms. This fact demonstrates that there may be a direct relationship between occlusion and a share of TM Disorders. The occlusal equilibration usually performed on these splints is occlusal applying prosthetic occlusal concepts questionable because not taking into account the physiology of the manducatory tract. The application of these concepts give unpredictable results. Publication by various specialized teams showed very poor results.
The therapeutic rehabilitation of functional chewing guidance has significantly reduced the indications of such splints: almost 90%
Remaining indications of dental splints
- Few indications of relaxation / deprogramming. When the anterior jig is insuficient to relax.
- Night guards, in case of bruxism. The flat planes, with posterior occlusal contacts have limitations. many bruxomen, do not tolerate: either they withdraw it, during the night, or they gnash on the splint and pierce it very quickly.
- We greatly prefer AJS (anterior Jig Splint), on which the patients can not gnash. Patients tolerate it much more easily, except in the presence of articular compression.
- There is no universal dental splint. We use 80% AJS, against only 20% conventional flat planes.
- The repositioning splints, longer have any indication. The discs are recaptured by the rehabilitation of molars chewing guidances.
Fig. D 18: View a conventional occlusal splint after adjusting and setting the MIO protrusion and laterality.
Fig. D 19: When the patient is resting on the jig, the condylar heads are in simple rotation. Even slight muscle contraction, results in an elevation and a forward moving of the condyles posture (lever of the second gender). If the contraction increases, limits to adaptation are quickly reached, nociceptive mechanoreceptors trigger protection mechanisms capable to relax muscles contraction that was compressing the disc.
Fig. D 20: Realization of a maxillary plate thermoformed, 1.5mm thick. With covering the palatal and buccal surfaces, at least 1mm, spontaneously allows the plate retention and the keeping of the superior and opposite arcade. A jig made of Revotek®, or of translucent resin, is then carried out on plate, at the level of the upper central incisors.
Fig. D21: The volume of the jig must allow the total disocclusion but minimal, of posterior teeth during the antero-posterior and transverse movements. The shape of the jig must allow a palatal support for the lower incisors, on a surface, flat enough to prevent the jaw to slide backward and to risk a joint compression, posterior. The AJS must be worn at night, not to exceed consecutive 8H. If there is a risk of displacement of mandibular incisors or intrusion, a simple thermoformed plate, identical to that of the maxilla, but with only 1mm thick, can be worn simultaneously at the mandible.
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