Difference between revisions of "4° Clinical case: Temporomandibular disorders"

== Abstract ==

{{ArtBy|autore=Gianni Frisardi}}

An article by Ahmad and Schiffman<ref name=":0">Mansur Ahmad, Eric L Schiffman. Temporomandibular Joint Disorders and Orofacial Pain. Dent Clin North Am. 2016 Jan;60(1):105-24. doi: 10.1016/j.cden.2015.08.004.Epub 2015 Oct 21.</ref> revealed interesting elements that call for a more in-depth analysis of the TMD phenomenon. The authors reported, in fact, that about 5-12% of the US population is affected by TMD and the annual cost of TMD management, excluding imaging costs, is about $4 billion. Interview Survey (NHIS) that included a total of 189,977 people, 4.6% (n = 8964) had temporomandibular joint and muscle disorders (TMJD).

Rightly says Magda Krasińska-Mazur et al.<ref>Magda Krasińska-Mazur, Paulina Homel, Andrzej Gala, Justyna Stradomska, Małgorzata Pihut. Differential diagnosis of temporomandibular disorders - a review of the literature.Folia Med Cracov. 2022;62(2):121-137. doi: 10.24425/fmc.2022.141703.</ref> that the correct diagnosis of temporomandibular disorders is based on anamnesis and a thorough physical examination, as well as the results of additional tests.....but which ones?{{q2|What could be the best approach to TMDs patients?|.... we will present in this context a diagnostic model in the context of restoring the functional masticatory condition of the patient in question}}So far we have discussed many aspects that in some way delay the differential diagnosis in patients who report overlapping symptomatology and various clinical manifestations, a differential diagnosis that if, on the other hand, performed correctly and quickly could save the subject's life as happened to our 'Bruxer' and unfortunately not to our 'Balancer'. The doctor's forma mentis in these cases is fundamental and the decisive element remains that of stepping out of the 'specialist context' in order to take an indeterministic and probabilistic view of medicine at the same time. This is no different with regard to patients actually suffering from TMDs because there is no real neuro-gnathological discipline, the diagnosis as well as the therapy of these subjects remains the standard one, namely gnathological. The discipline of gnathology, although very valid, is also limited because it restricts the field of the 'observable' to the occlusal parameter, disregarding everything else that is part of the masticatory neuromotor network and beyond.<ref>Chiara Vompi, Emanuela Serritella, Gabriella Galluccio, Santino Pistella, Alessandro Segnalini, Luca Giannelli, Carlo Di Paolo. Evaluation of Vision in Gnathological and Orthodontic Patients with Temporomandibular Disorders: A Prospective Experimental Observational Cohort Study. J Int Soc Prev Community Dent PMID: 33042891 PMCID: PMC7523923 DOI: 10.4103/jispcd.JISPCD_273_19</ref> We will present this clinical case of a patient with DTMs to give a significant clinical diagnostic/therapeutic change in the field of 'Functional Neuro Gnathology' calling it, precisely, the NGF method.  

[[File:Clicker 00.jpg|thumb|'''Figure 2:''' Oral situation of the patient affected by TMDs showing the ant erior cross bite]]

[[File:Clicker 01.jpg|thumb|alt=|left|615x615px|'''Figure 3:''' Neurognathological Functional electrophysiological tests]]

As has now been documented in the previous chapters of Masticationpedia, the heart of the scientific philosophy of Masticationpedia is substantially the normalization of masticatory functions to the Central Nervous System and trigeminal peripheral _tCNS and not to dental occlusion. This is able to couple the occlusal abnormality to the 'state' conditions of the tCNS as well documented in the first chapter '[[Introduction]]' where we showed a perfect trigeminal electrophysiological symmetry in the subject with severe dental malocclusion and a frankly asymmetric neuromotor condition in a subject with perfect occlusion after being treated with orthognathic surgery. The electrophysiological tests in subjects with TMDs are limited to the bilateral Motor Evoked Potentials of the trigeminal roots which we have precisely put over the years called bRoot-MEPs,<ref name=":1">Frisardi G. The use of transcranial stimulation in the fabrication of an occlusal splint.J Prosthet Dent. 1992 Aug;68(2):355-60. doi: 10.1016/0022-3913(92)90345-b.PMID: 1501190</ref> from the jaw jerk<ref name=":2">Cruccu G, Frisardi G, van Steenberghe D. Side asymmetry of the jaw jerk in human craniomandibular dysfunction. Arch Oral Biol. 1992 Apr;37(4):257-62. doi: 10.1016/0003-9969(92)90047-c.PMID: 1520092</ref> performed while keeping the mandible in the rest position (Jaw jerk in rest position) and the jaw jerk keeping the jaw closed with moderate muscle activity (jaw jerk in occlusal position).

In figure 3 we can see the responses of the motor evoked potentials of the two trigeminal roots, the jaw jerk in the rest position and in the position of maximum intercuspidation. In particular, the Nervous system responds to Transcranial Electrical Stimulation of the trigeminal roots with two evoked potentials that are perfectly symmetrical both in latency and in amplitude and specifically the latencies are positioned at an onset of <math>1R= 2,01</math>ms and <math>1L= 1,99 </math>ms while the peak-to-peak amplitudes <math>2R-3R= 5</math> mV and <math>2L-3L= 5,2</math> mV. This result is fundamental for the differential diagnosis between organic and functional pathologies, in fact, it demonstrates that the system is organically symmetrical and synchronous and this determines the term that we will see recur in a decisive way in the continuation of the Masticationpedia chapters called 'Organic Symmetry'. Bear in mind right now that the 'Organic Symmetry' parameter will be considered an element of 'Normalization' of the trigeminal reflex responses as its latency and amplitude symmetry indicates a perfect 'state' of integrity of the  _tCNS and that at the same time one should expect an equally 'state' of functional symmetry due to trigeminal reflex responses. Let's see, therefore, the trigeminal functional 'state' of the  _tCNS by analyzing the jaw jerk.

The stretch reflex test called jaw jerk was performed keeping the mandible in rest position to distinguish the input component to the tCNS excluding the input of the periodonatal receptors. The results were not encouraging due to the relative asymmetry of latency (<math>1R= 8,5</math>ms and <math>1L= 7,5</math> ms) and peak-to-peak amplitude (<math>2R-3R= 0,3

</math>mV; <math>2L-3L= 0,6</math>mV). In particular, the latency delay could be explained by a facilitation on gamma motor neurons, in contrast with the study by Kitagawa et al.<ref>Kitagawa Y, Enomoto S, Nakamura Y, Hashimoto K. Asymmetry in jaw-jerk reflex latency in craniomandibular dysfunction patients with unilateral masseter pain. J Oral Rehabil. 2000 Oct;27(10):902-10. doi: 10.1046/j.1365-2842.2000.00595.x.PMID: 11065026</ref> in which it is asserted that the facilitation on the ipsilateral side could be produced by an enhancement of the gamma drive induced by a prolonged nociceptive stimulation. In our case the most significant datum is the difference of <math>\simeq 50%</math> with reduction on the right affected side. We have noticed in our studies that in the rest position the jaw jerk also shows a dependence not only on the acceleration of the trigger stroke but also on the spatial position of the jaw as it is not conditioned by the occlusal position.<ref name=":2" />

The jaw jerk, keeping the mandible in a position of centric occlusion, performed to verify the contribution of the periodontal receptors together with the muscle and tendon proprioceptors, was obviously facilitated by the dental contact but the asymmetry in amplitude (<math>2R-3R= 0, 1

</math>mV; <math>2L-3L= 1</math> mV) increased. This result agrees with what was stated in a study by Yoshino T et al.<ref>Yoshino T.Kokubyo Gakkai Zasshi. Effects of lateral mandibular deviation on masseter muscle activity. 1996 Mar;63(1):70-87. doi: 10.5357/koubyou.63.70.PMID: 8725358 </ref> in which the mandibular position was deviated by 0.5, 1.0, 1.5, 2.0 and 3.0 mm to the right and left from a reference position corresponding to the rest position. Jaw jerk amplitude on the mediotrusive side increased primarily in proportion to mandibular deviation. The study concludes by suggesting that jaw jerk may aid the clinical examination of minor mandibular deviations. The conclusion of this 1st trigeminal electrophysiological step was to ascertain the organic integrity of the _tCNS through the symmetry and synchronics of the _bRoot-MEPs,<ref name=":1" /> and consider it as an 'Organic Symmetry',<ref>G Frisardi, G Chessa, A Lumbau, S Okkesim, B Akdemir, S Kara, F.Frisardi. The Reliability of the Bilateral Trigeminal Roots-motor Evoked Potentials as an Organic Normalization Factor: Symmetry or Not Symmetry. Dentistry S2 8, [tel:2161-1122 2161-1122]</ref> i.e. normalizer of the masticatory neurophysiological process while the asymmetries of the jaw jerk a functional disorder due to an unbalanced peripheral input or an inhibitory process on the trigeminal motoneurons of the nociceptive type. In essence, the conclusion of a mandibular spatial disorder would seem more indicative, which we will ascertain later when the Neuro Evoked Centric Relationship is performed to verify the physiological spatial position.   

[[File:Clicker 3.jpg|'''Figure 4:''' Silent period of masticatory muscles and representation of areas of interest marked with arrows.|alt=|thumb|250x250px]]

Figure 4 shows the neuromuscular responses of the silent period to chin percussion through a triggered neurological hammer when the patient was asked to clench her teeth maximally. If from a neurological point of view it is not possible to highlight elements referable to organic alterations of the _tCNS, some electrophysiological characteristics, however, are to be referred to a functional disorder of the system. In the upper trace, a decrease in the motor neuron reactivation phase can be seen immediately following the silent period. The possible neurophysiological mechanism capable of determining a similar decrease in facilitatory activities on the mandibular silent period can be ascribed to a change in the spindle motor drive induced by the input of muscle proprioceptors and nociceptors. The neuronal network of this process would take place through a loop formed by: muscle nociceptive afferents, the subnucleus caudalis of the V, inhibitory interneurons on static motor neurons and, as a last link, the modulation of the sensitivity of the neuromuscular spindles..<ref>Ro J.Y.,Capra  N.F.: Physiological evidence for caudal brainstem projections of jaw muscle spindle afferents.Exp.Brain Res 1999;128: 425-434</ref> <ref>Capra N.F.,Ro J.Y.: Experimental muscle pain produces central modulation of proprioceptive signals arising from jaw muscle spindles. Pain 2000; 86: 151-162.</ref><ref>Appelberg B.,Hulliger M.,Johansson H.Sojka P.: Actions on g-motoneurones elicited by electrical stimulation of group III muscle afferent fibers in the hind limb of the cat.J Physiol. 1983;335: 275-292.</ref><ref>Macefield  G.,Hagbarth E,Gorman R, Gandevia SC,, Burke D.: Decline in spindle support to a-motoneurones during sustained voluntary contractions.J.Physiol 1991;440:497-512.</ref><ref>Mense S.,Skeppar P.: Discharge behavior of feline gamma-motoneurones following induction of an  artificial myositis.Pain 1991; 46: 201-210.</ref><ref>Pedersen J, Ljubisavljevic M, Bergenheim M.,Johansson H.: Alterations in information trasmission  in ensembles  of primary muscle spindle afferents after muscle fatigue in heteronymous muscle.Neuroscience 1998;84: 953-959.</ref>  Also in this context the inhibitory component most likely prevails over the excitatory one and this could be ascribed to a malocclusion as we will see later. In particular, it can be noted the overlapping of the jaw jerk behavior, previously tested, in a path rectification condition. The arrow indicates the jaw jerk on all traces and the decrease in amplitude can be observed for the right masseter while it is relatively symmetrical on the temporal muscles.<br />

On this subject unfortunately there are innumerable conceptual conflicts redundant regularly coming back into vogue after a period of years such as the gothic arch tracing method to determine the centric relationship of full dentures, as suggested by Zhou TF et al.<ref>Zhou TF, Yang X, Wang RJ, Cheng MX, Zhang H, Wei JQ.Beijing Da Xue Xue Bao Yi Xue Ban. A clinical application study of digital manufacturing simple intraoral Gothic arch-tracing device in determining the '''centric''' relation of complete dentures. 2023 Feb 18;55(1):101-107. doi: 10.19723/j.issn.1671-167X.2023.01.015.PMID: 36718696 </ref> From what has been exposed in all the chapters previously published on Masticationpedia, it is clear that the approximation of manual methods or vague interpretations derived from a logic of verbal language cannot be represented in the scientific philosophy of Masticationpedia which tends to focus on a mesoscopic model more than macroscopically descriptive and formal through statistical mathematical models as we will see below. Therefore we do not share the opinion of Zhou TF et al but absolutely in line with the concepts expressed by Silva Ulloa S. et al.<ref>Silva Ulloa S, Cordero Ordóñez AL, Barzallo Sardi VE. Relationship between '''dental''' '''occlusion''' and brain activity: A narrative review. Saudi Dent J. 2022 Nov;34(7):538-543. doi 10.1016/j.sdentj.2022.09.001. Epub 2022 Sep 16.PMID: 36267531 </ref> in which it is concluded that the sensorimotor cortex is affected by changes in occlusion and it is hypothesized that occlusion may play an important role in the development of diseases, from anxiety and stress to Alzheimer's disease and senile dementia. We also share the heartfelt suggestion of Silva Ulloa S. et al. in which she urges dentists to consider that alterations in the occlusal pattern during chewing can lead to changes in the activation of several brain regions related to memory, learning, anticipatory pain and anxiety.  

Sebastian Silva Ulloa, Ana Lucía Cordero Ordóñez, Vinicio Egidio Barzallo Sardi  }}Therefore, it is essential to operate in synergy with the trigeminal neuromotor content in order to have an 'Observable' more indicative of the masticatory reality and in this case of the real spatial position that the jaw wants to reach beyond the dental interference. To achieve this target we have developed a method of simultaneous Transcranial Electrical Stimulation of the trigeminal roots which evokes a direct response of all the masticatory muscles which we call _bRoot-MEPs as previously mentioned which has an indication of the 'state' integrity of the _tCNS and at the same time it determines an elevation of the mandible from the rest position to the Occlusal Centric. This Centric has been named by us Functional Neuro Evoked Centric. (Figure 5)  

As we can see, starting directly from a neurological context, using advanced trigeminal electrophysiological technologies, we have avoided the presence of destructuring of the _tCNS and contextually highlighted a spatial-type occlusal disorder. The mandible with this method which generates a synchronous action potential of all the muscles innervated by the trigeminal roots, apart from conditions of marked destructuring of the ATM, generates a perfectly physiological closure which in this case is interrupted by the presence of a dental interference of the element 21 which comforts us in continuing the functional neurognathological treatment.

Regarding the treatment of patients with TMDs there are still many strategic-conceptual conflicts such as, for example, the use of TENS<ref>Didier HA, Cappellari AM, Gaffuri F, Curone M, Tullo V, Didier AH, Giannì AB, Bussone G. Predictive role of '''gnathological''' techniques for the '''treatment''' of persistent idiopathic facial pain (PIFP). Neurol Sci. 2020 Nov;41(11):[tel:3315-3319 3315-3319]. doi: 10.1007/s10072-020-04456-9. Epub 2020 May 21.PMID: 32440980</ref> which the RDC protocol has considered clinically invalid as much as from a neurophysiological point of view TENS is not an appropriate method for not being able to evoke a response from all masticatory muscles but only the superficial ones. In this limitation lies the spatial error of the mandibular position which would be in a more anterior position due exclusively to the motor response of the masseter muscle (a topic which will be dealt with in the section 'Crisis of the Paradigm').  

In figure 6a we can see the structures of the crowns in the mouth on which the ceramic will be stratified and which will be covered with Aluvax wax to determine the Functional Neuro Evoked Centric. The decision to incorporate the four molars in the rehabilitation was made because these elements are crucial for occlusal stability but also for mediotrusion as we will see below. The exact mandibular position requires a third anterior point and for this reason, also considering the wear of the incisions and the importance of a normocclusion of the anterior sector, the involvement of the incisors was decisive for Centering the mandible in the optimal position (figure 6b) . Obviously, everything is brought back into articulate with mold waxes on Empress crowns. (figure 6c)

For Neuro Gnatologic Functional detail, rehabilitation model called 'NGF Index' from which a whole scientific process will be initiated which will lead to a diagnostic paradigmatic model called 'NGF Index' in the 'Extraordinary Science' section, means an occlusal adjustment normalized to trigeminal neuromotor symmetry . To achieve this goal, gnathological replicates (articulated) and above all the ability to read the evoked and reflex responses of the tCNS in different occlusal situations are fundamental. For this reason, only the active centrics of the Empress crowns were stratified on the four lower molars. (figure 7)

<center>

Figures 8a and 8b show the extraordinary differences in the trigeminal neuromotor response due, being of a functional type, to a mandibular spatial change and an accurate neurognathological occlusal balancing. In fact, one can see a symmetrization of the jaw jerk on the right masseter, a decrease in the duration of the mechanical silent period and above all an optimal motoneural reactivation after the silent period (rebound effect) which means safety in the total and immediate reactivation of the motoneural discharge. Once this trigeminal neuromotor re-symmetrization has been documented with irrefutable data, it is possible to move on to finalizing the clinical case.

The finalization of the definitively diagnosed clinical case of DTMs resulted in a restoration of the masticatory function, disappearance of the symptoms as well as an aesthetic improvement. The various phases of the rehabilitation can be followed in the gallery of images in figure 9. In particular, the Functional Neuro-Evoked Centric position is not only centered having moved slightly to the right but also retruded. It is interesting to make a comparison with figure 5a to understand the spatial differences. Element 22, in fact, is no longer in crossbite but in a head-to-head position while element 23 has a much more incisal centric contact with respect to the previous clinical situation, so as to note the occlusal space in the medial area of element 24 which it was generated with the current mandibular spatial position determined with the Functional Neuro Evoked Centric. This new occlusal arrangement was only possible because the stable and mainly frozen centric position in the molar sector. The molars through the previously exposed neuromotor balance on the centric cusp stabilize the occlusion and generate a bilateral balance in the mandibular movements as will be shortly described.

<center>

<nowiki/>{{Bib}}

<references />