By Dr. Andrea Gizdulich
The most recent knowledge of neuromuscular physiopathology has shown that temporo-mandibular arthropathies are the expression of a more generalized picture of disorder that affects the entire stomatognathic system and can also involve other systems.
The most commonly found alteration is the intracapsular pathology that clinically begins with a small vibration or noise, which is clearer, more appreciable in the oral opening phase but also present in the closure that is defined, with an onomatopoeic "click" term. The genesis of these disc condylar incoordinations is to be found in the anomalous dental fit that triggers and supports the pathological mandibular posture, forcing the muscle-articular system into the best possible balance. The loss of this precarious balance in the joint and therefore the appearance of the full-blown pathology will be due to the exhaustion of personal adaptability and consequently to the collapse of the support structures. It is in fact recurrent that the pathological dental occlusion occurs in forced mandibular retrusion with sliding back of the condyle and consequent stretching of the external pterygoid muscle and of the intra and extracapsular structures. However, from the prognostic point of view, the time of interception of the joint problematic that plays a dominant role in the evolution of the anatomical damage very often devoid of pain, is therefore extremely underestimated. On the theoretical level any alteration of the dental occlusion can lead to a morpho-functional degeneration of the temporomandibular joints; however, this particular clinical expression is commonly found in patients with significant vertical dimension losses. Nevertheless, there are rare cases in which it is possible to verify a moderate degree mandibular dislocation, without loss of vertical dimension, but sufficient to generate the joint disorder. For this purpose a 69-year-old woman was examined who complains of a slight noise at the left temporomandibular joint. The anamnesis also shows the presence of a pain referred to the joint itself with irradiation to the ipsilateral ear. The symptomatology appears to be of very recent onset, that is almost concomitant with the realization of a fixed prosthetic reconstruction against the second upper left premolar completed a few weeks earlier, by a dentist colleague. The palpation of the articular regions reveals the presence of an opening click against the left joint with a modest tenderness of the retrodiscal tissues examined in maximum opening. No muscular tenderness was detected in the masticatory and cervical muscles.
a computerized scan of the mandibular movements was conducted to verify and measure, without operator interference, the presence of alterations of the usual pathways attributable to mechanical obstacles in the movement of the joint heads. This study was enriched by the simultaneous analysis in speed of the maximum opening movement of the mouth and subsequent closure. The assumption formulated is that of analyzing with sufficient precision any mandibular dislocations, deviations or deflections during normal movements almost always associated with inevitable slowdowns: the articular click must be considered a real anatomical obstacle that is realized at the time of the recapture of the articular disk dislocated. The tracks thus recorded showed a maximum aperture of 50.9 mm which is accomplished with a slight irregularity in the frontal plane in the intermediate phases of opening and closing.
On the other hand, the speed diagram clearly allowed us to identify an average opening speed of 267.6 mm / s and a closing speed of 260.0 mm / s with peaks over 400 mm / s. At less than 20 mm from the maximum opening it is also possible to highlight an abrupt and short-term slowdown followed by a speed recovery that is reset when the jaw exhausts the opening phase and prepares for the next closing. This slowing down occurs in an almost specular manner in the last millimeters of the closing path, near the dental contact that stops the movement.
Stimulation with low frequency preauricular TENS was then applied for 45 minutes with the aim of relaxing the stomatognathic and cervical musculature and identifying the neuromuscular trajectory which from the physiological rest position should be traveled to reach the correct dental contact.
A new kinesiographic examination was then carried out to visualize the neuromuscular trajectory of occlusion calculated following the path drawn by the mandibular movement that is realized with the isotonic contraction evoked by electrical stimulation (TENS). This method is necessary in the first place to measure which is the usual occlusion of the patient with respect to the ideal one which should allow the arrest of the mandibular ascent along the same trajectory at a distance of 1.5-2.5 mm (physiological free space) from the position of mandibular rest.
In the case examined the free space was found to be 1.4 mm but with a position retrusa compared to the physiological one of 0.5 mm on the sagittal plane and aligned on the frontal one.
The presence of a physiological free space and the concomitant slight sliding backwards in maximum intercuspidation led us to believe that the only intervention necessary was to subtract from the dental surfaces those contacts that prevent the attainment of the myocentric position. This maneuver was strictly carried out by evaluating not the usual contacts but the automatic ones induced by the adequately increased intensity TENS stimulation. The constant need not to interfere with the patient has made us prefer the use of adhesive joint waxes rather than normal copying papers. In this way, those contacts were identified on the cuspid sides usually avoided because they were considered harmful by the patient's proprioceptive system. Once marked with a demographic pencil they were reduced by coronoplasty in order to respect the height of the cusp and the depth of the pit but facilitating entry and exit.
A new kinesiographic examination was then carried out on the same day which confirmed the correct respect of the previously measured vertical dimension and a substantial coincidence between the neuromuscular trajectory and the habitual one traveled autonomously by the patient.
The patient was then checked at about a week and about a month after the correction operation and remotely monitored for a period of 6 months during which Posselt's individual diagram and speed test were repeated.
The patient showed clinical signs of improvement during the first and only day of dental coronoplasty and reported the disappearance of the pain symptomatology with a noticeable reduction in joint noise, which then completely disappeared after about a month.
The last traces conducted show a better ability to open the mouth both in a qualitative sense (reduction of irregularities on the frontal and sagittal planes) and in a quantitative sense (increase of the maximum oral opening). The speed test also shows how these movements take place without showing any major slowdown in both the closing and opening paths.
All the parameters examined were decidedly more favorable than the respective ones recorded in the first visit and the patient confirmed the substantial benefit of the correction of the dental surfaces by resuming the normal course of her activity, first compromised by a non-stabbing but persistent pain. This aspect unequivocally describes the pathogenesis of condylar disk incoordination: the dysfunctional picture of the neuromuscular system with involvement of the pterygoid muscle in both ends must be connected to the ever present pathological mandibular posture. The condition of muscle spasm associated with the inevitable stretching of the same fibers for rear-view
condylar and the need to reshape the articular surfaces to guarantee the functioning of the joint are the substratum in which all the pathogenic noxae that alter the dental matching converge. If these assumptions are always present in the disk-condylar pathology, they cannot be considered sufficient, since, as the patient says well, they can live together well with these conditions until these tissues are able to withstand stress. A direct mandibular trauma, an effort to maintain a prolonged oral opening (wisdom tooth extraction), a slight further occlusal destabilization or even no apparent phenomenon can one day lead to an inability to bear stress further and therefore to determine the overt symptomatology that it cannot be considered other than the onset of a problem that has its roots in the near or remote past. However, it is doubtful that the joint pathology represents only one side of a disorder that affects the entire stomatognathic apparatus and beyond. Unlike what was believed in the past, the joints cannot be considered dominant in the masticatory function but rather blameless victims when the complex intrinsic and extrinsic ligamentous system suffers sometimes irreparable damage.
