Phopathology of the Temporomandibular Joint (TMJ)

Fundamental considerations on the morphophysiology and morphopathology of the temporomandibular joint (TMJ) Ana-Maria Grumezescu Iancu1, Dragoº Totolici2, Lucian Ieremia3 1 Frankfurt am Main, Germany 2 Constanþa, 3 Târgu Mureº, Romania Summary The authors evidence the importance of being knowledgeable as regards the TMJ anatomy as well as its specific peculiarities are interpreted through the new intersystemic medical vision of contemporary Gnathology. The nine essential features presented above open the perspective of assimilating morphophysiology and morphopathology knowledge on this articulation, which is a unique item in its capacity as the posterior anatomic determinant of functional occlusion. Keywords: tmj morphophysiology and pathology, posterior anatomical determinant, functional occlusion.. without discal-condylar implications - Note I - (Ieremia et al., 1987, 1999, 2000). Most often, the appearance of 1. The need of getting acquainted dyshomeostasis of this complex ensemble with the TMJ anatomy will directly or indirectly generate baneful consequences on other biosystems of the human organism as well. Due to its poly- One of the most significant conquests morphic symptomatology, usually charac- of contemporary Gnathology is the integra- terizing a syndrome, and to an intracapsular tion of all dental braches within the frame of or extracapsular pathology produced by pre- Biology under the name of Dental Medicine. disposing, initiating or perpetual multi- Following the emergence and applica- causal etiological risk factors (that can mix tion of multiple technical means of macro- up and reciprocally condition themselves scopic, microscopic and radiological clini- through different intimate mechanisms), the cal examination of TMJ, of refining the orofacial structures are equally affected, complex means of epidemiological investi- against the aggravating background of over- gation – analyzed by the help of anamnestic lapping certain systemic diseases (Pullinger and objective indices, processed by comput- et al, 2000). Such craniomandibular dys- er programs – a new methodology was set function is the consequence of imbalance, up. It allowed extremely relevant results, by having three basic origins: using an intersystemic medical reasoning, - postural, through the functional dis- which was able to assess the functional or turbance of the muscles which connect the dysfunctional status of the stomatognathic mandible to the skull, the vertebral column system, also termed orofacial (OFS), with or and the shoulder girdle; 38 OHDMBSC - Vol. IV - No. 4 - December, 2005 - lingual, through the dyspraxia of etiology by explaining the pathology of infantile deglutition; morbid entities of the TMJ, still represent - dental, through malocclusion with nowadays a controversial subject. It deviations in teeth gearing, due to traumatic demands knowledge of the complex anato- occlusion (TO). my of this articulation, which actively takes The correlation between posture and part in achieving the essential functions of the mandible is observed through the recip- the stomatognathic ensemble, that R. rocal influence transmitted. For instance, Slavicek (1996) considers being a “cyber- when the mandible is imbalanced because of netic supersystem”. the tongue or teeth, it will systematically Not last, in our opinion, adequate trigger posture alterations, converting into a importance should be given to the occlusal source of individualized pathology. Equally, function (OF), which represents the physio- the posture acting on the mandibular bone logical condition of dental arches confronta- can generate biomechanical changes, tion during the functioning of the stomatog- accompanied by TMJ pain. nathic system, through mandibular chocking Such significant observations derive and guidance. Two significant capabilities from the concept of muscular, articular are distinguished: masticatory and postural. and facial integration, which states that the An optimal interarch gearing through three-dimensional equilibrium of the stable, symmetrical and multiple occlusal mandible as against the skull and face can- stops will influence an adjusting modeling not be considered functional unless the ele- of the articular tubercle and of the ments that make up the OFS (TMJ, the mus- mandibuar condyle head, thus achieving cles and aponeurotic network) do not cause consistency between the condylar slope, the any damage to the organism. incisive slope and the skeletal frame. This concept named “of chains”, elab- This favorable correlation will allow orated by Fonder and May (cited by F. the dental arches to withstand as much as Serviere, 1989) and sustained by G. Struyf- possible the numerous parafunctional Denys (1982) has three important corollar- aggressions (bruxism, vicious habits), lying ies: at the boundary between physiologic and - the functional imbalance of a muscu- pathologic. lar organ, characterized by spasm or According to M. Watanabe et al. hypotonia will cause, by contiguity, a (2001), B. Kazuyoshi et al. (2001), such similar reaction in the neighboring statement can be considered as pertaining to muscles, of the same dynamic system; the physiologic, by taking part in the main- - an articular dysfunction generates tenance of psychological balance of the another remote dysfunction, in respect individual in the OFS homeostasis. to the convergence of main constraints If the intensity of parafunctional mani- induced by an initial lesion; festations is important and repetitive, it - aponeuroses constitute a systemic becomes a pathological risk factor complex of tensions, at the level of (Amemory, 1999; Alamaudi, 2001; Molina which imbalances produced by con- et al., 2001; Sari et al., 2001; Koyano et al., straints, trauma and inflammatory 2003), causing structural alterations (patho- pathology reverberate. logical dental abrasions, teeth drifting, Regardless of all the above-mentioned myalgia, arthropathies) on the ground of aspects, the assessment of temporomandibu- remodeling the hard components of the TMJ lar disorders in literature, the systematiza- with regressive, progressive or combined tion of pathology and the identification of specificity (Kurita et al., 2000, 2001; 39 OHDMBSC - Vol. IV - No. 4 - December, 2005 Ieremia et al., 2004 a, b, c). tion of this pathology is required, by the cor- According to H. A. Israel et al. (1999), rect assessment of evolutional stages of the K. Yamada et al. (2001), the excessive TMJ craniomandibular painful dysfunctional syn- involvement in bruxism, generated by max- drome (CMPDS). illary clenching and interarch constriction, Consequent to this estimation, the mon- brings about changes in the structure of the itoring of individuals epidemiologically articular cartilage, with the specific bio- investigated, the choice and application of chemical consequences of intracapsular adequate therapy with individualized and pathology of degenerative nature. prophylactic character, followed by the con- This conclusion was borne out by N. firmation of treatment efficacy by the help Stegena et al. (2000) and by other of computerized medical programs, are per- researchers as well (Lyons, 2001; formed. Piotrowski et al., 2001). Although bruxism and certain vicious oral habits are reckoned 2. Specific peculiarities of the TMJ as possible causes responsible for excessive dental wear, abfraction and TMJ dysfunc- Willing to contribute to applying mod- tion, unfortunately no cause has yet been ern methodology of contemporary established. Gnathology through investigations, in order It seems though that personal dissatis- to trace out this pathology in human com- faction, psychological stress and even diffi- munities (quite frequent at all ages and cult social conditions can be considered risk sexes) we will demonstrate what the nine factors that generate stomatognathic ensem- unique features of the TMJ consist of as ble dyshomeostasis, with discal-condylar compared to the rest of the articulations in dysfunctional implications at the TMJ level the human body. (Macfarlane et al., 2002; Johansson et al., Such clinical functional morphology 2004). data, interspersed with notions of physiolo- Quite recently, the most plausible gy, physiopathology and macroscopic bio- hypothesis is that of excessive pathological mechanics, colligated with light and elec- dental abrasion, of extended partial unre- tron microscopy and histochemical analy- stored edentation or iatrogenically restored, ses, have opened new prospects towards on the priority background of psychogenic unraveling intimate mechanisms of normal factors. This can reduce the adaptive capac- or pathological biological processes. ity of the TMJ and associated tissues, main- It is well known that the TMJ, as a pos- ly favorizing the evolution of nocturnal terior anatomical determinant of occlusion bruxism, generating tissular complications (Figure 1), contributes, through its anatomi- of the hard and soft articular components cal and biomechanical peculiarities to carry- (Ieremia et al., 2001, 2002), and leading to ing out OFS essential functions through the diagnosis difficulties (Grumezescu et al., subsequent significant components: the 2004). articular surfaces, the disc, the capsula and As TMJ dysfunction is the main cause its own intraarticular and extraarticluar liga- of nonodontogenic algia of the OFS territo- ments and the dynamizing muscular com- ry and includes many morbid entities affect- plex. ing the masticatory muscles, TMJ and other This articulation is permanently

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