CATEGORY 84 AUSTRALASIAN DENTIST LINICAL Counselling for the temporomandbular jaw joint – a ginglymoarthroidal joint The TMJ jaw joint hinges (ginglymoid joint) in one plane which involves the head rotating in the cup during the first 15 mm of mouth opening. More opening will result in the head gliding (arthrodial joint) along the articular eminence in a curvilinear or straight line resulting in a left, right or forward jaw movement (Dr. G.P. Suhasini from SVSU). It is the author’s belief that counselling patients involves the principle that small mouth opening encourages disc stability as the head is in the cup hinging on a stationary disc. Whereas large mouth opening for a TMD patient should be discouraged as during extreme gliding of a moving slightly displaced disc, joint instability can ensue. With bruxing this instability often develops into a displaced disc that clicks, followed by locking and finally jamming or non-reducing resulting in permanent restricted mouth opening and intractable pain. Destructivehabits (AlpernandWharton 1997) require counselling as these can result in stretching of the TMJ outer ligaments creating a hypermobile (De Coster et al. 2005) or lax jaw joint. This results in an unstable joint and the development of the abovementioned symptoms. Occluso-mandibular vectors during destructive habits The location, size and shape of opposing teeth influences the bite or occlusion which in turn affects the directional movement of the lower jaw. Evaluating the direction, or vector, of the lower jaw requires an occlusomandibular analysis (Darveniza 2001). An oral examination involves occlusomandibular analysis of hinge, left, right and forward mandibular movements and patients’ habits. These vectors should be recorded (Darveniza 2022). Occlusomandibular analysis of hinge occlusion ideally should be point centric and without damaging mandibular vectors including a retrusive vector (Part 1 Figs. 6, 7, 9 and 13) (Darveniza 2023), and lateral or forward vectors. Nevertheless, allowances can be made requiring the development of point centric. Against this level of precision, Ramfjord and Ash have claimed that a forward slide or ‘long centric of 0.3 to 0.8mm seems to be within the adaptive range of the overwhelming majority of patients’ (Ramfjord and Ash 1971). Occlusomandibular analysis in lateral occlusion ideally should show a moderately angled vertical canineguidancepathsupporting the contralateral condyle as it translateswith the disc out of the fossa resulting in a protective vertico-lateral occluso-mandibular vector (Darveniza 2001). The mandibular vectors for early, mid and final paths in lateral occlusion and protrusive occlusion are observed and charted (Darveniza 2022) (Fig. 15, 16 and 17). Occluso-mandibular analysis of mandibular protrusion should be bilateral contacting of teeth with a sagittal vector and not illustrate a unilateral tooth supported movement with a nonsagittal vector (Fig. 15). The destructive lateral vectors include horizonto-lateral Part 2: ‘Full Counselling’ during ‘Full Occlusal Therapy’ with habit modification, sleep posture analysis and instructions for delivering a ‘Fully Protective Occlusal Splint’ to manage TMDs. By Dr. Michael Darveniza MDSc PhD (Qld) FRACDS Fig. 17 The left photograph illustrates an unprotected left lateral occlusion guided horizonto-laterally with 33 on 23, 32 on 22 and, 41 and 42 on 21. The right photograph shows a continuation of the left movement now in extreme left lateral cross-over resulting in 33 reaching distally all the way to the 24, while 23 wedges against the lingual surface of 32. This cross-over produces a destructive disto-horizontal vector resulting in a retrusive mandibular movement allowing the left condyle to compress the disc against the ear with concomitant symptoms of left TMJ pain, clicking, tinnitus and hyperacusis. Fig. 16 The left photograph illustrates an unprotected right lateral occlusion, guided horizonto-laterally by 42 on 12. The right photograph illustrates extreme right lateral cross-over with 41 now on 12 and 11 with a perceived concomitant stretching of the contralateral left TMJ ligaments. Fig. 15 The left photograph of a TMD patient with disc displacement and left TMJ pain, clicking, tinnitus and hyperacusis shows centric occlusion. The 43 is opposite the 12 in an Angle’s Class 3 relationship while the 33 is occluding with the 23 and 22 in a Class 1 and 3 relationships. The right photograph illustrates an unprotected unilateral guided protrusive movement with 41 on 21 with a non–sagittal vector.
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