CATEGORY 100 AUSTRALASIAN DENTIST molar guidance in 1992 to bio-design a lateral and protrusive occlusion and will be reported in a future paper. The author has observed clinical researchers, restorative dentists and prosthodontists who perform a functional occlusal analysis often erroneously consider that if canines are contacting during lateral movement, then this is a protective lateral occlusion. A new era in occluso-mandibular analysis is required with an emphasis on the length and simultaneous vector of early, mid, and final paths in lateral and protrusive occlusomandibular movement. The resolved component of each occluso-mandibular movement in the direction affecting the TMJ’s is the ‘occlusal key’. Looking at tooth contacts in isolation is an obsolete paradigm for the author. The philosophy of ‘Full Occlusal Therapy’ involves new terms and hence a new language to describe previously stated ways to evaluate and treat TMD patients. Counselling with TMJ diagrams Patients and many clinicians have no idea what the detailed anatomy of a TMJ is or how it functions and possible occlusomandibular reasons why it malfunctions causing a temporomandibular disorder. Counselling starts by explaining the basic components of the TMJ as illustrated (Fig. 1) along with the occlusal scheme often found LINICAL in a 14-year-old patient or older patients who have not addressed their unprotected occlusion. The last exposed tooth or second molar is often the first contact (premature contact) in hinge bite or hinge occlusion along with no contact or an open bite between all other teeth (Fig. 1). This often occurs because the erupting wisdom teeth push against the adjacent second molars resulting the teeth being pushed out of their sockets and being high in hinge bite. The lower jaw reacts by protruding forward and to one side to escape the premature molar contact and thereby reducing the open bite to allow the teeth to maximally contact or interdigitate into a new adaptive jaw position called centric occlusion. Unfortunately, this author believes that this adaptive centric occlusion occurs at the detriment of the discs, which become displaced (Fig. 2) to accommodate and stabilize the off-centre lower jaw by shimming the thicker portion of the disc between the condyle head and fossa or cup. The resulting displaced disc, and postured off-centre lower jaw, directly affects the health of the TMJ’s and associated ligaments and musculature. A TMD then develops with common symptoms of facial pain and headaches, noisy jaw joints, restricted mouth opening, difficulty in chewing and jaw locking when a jammed or non-reducing displaced disc develops. The question a patient often thinks or asks is ‘howdoes this piece of plastic (splint) make my jaw joint symptoms better?’. The author uses figure 3 to explain the answer to this question, as follows. The basic concept is that an occlusal splint has to be designed to optimally decrease jaw activity thereby creating an environment of maximum facial relaxation. The ‘Fully protective Occlusal Splint’ design incorporates multiple design features including a thick splint with protective design elements for hinge, left, right and forward bites or jaw movements. If the facial musculature is relaxed this will, in turn, relax the superior head of the lateral pterygoid muscle (long pointed red arrows) as it attaches to the capsule on the forward portion of the disc. If the forward portion of the disc is relaxed then this will allow the strong posterior elastic ligament (rounded red arrows) to retract the disc back towards its original centred position in the TMJ, over four splint adjustments (SA1, SA2, SA3 and SA4) (Fig.3). The progress of this retraction is also hindered by suction created by clenching (short pointed arrows) and the presence of adhesions (green broken springs) and destructive habits performed by the patient (Fig. 3). The methodology used by this author to remedy a TMD involves ‘Full Occlusal Therapy’ which has to be performed slowly, sequentially and methodically to allow disc re-centring and facial muscle lengths equalising before improving the bite (Fig. Fig. 4 Occlusal views illustrate after occlusal equilibration on crowns a protective hinge occlusion achieved with bio-designed spheroidal supporting cusp tips and centric platforms of 1.5-2.0 mm in diameter. Occlusal registration was performed largely with Accufilm (Parkell, Farmingdale, New York, USA) using two layers of red/black registration paper together in articulating forceps for larger centric stop area of registration as illustrated. Fig. 5 An occlusal view illustrates a bio-designed anterior guidance at the groundin stage during an occlusal reconstruction. Note the lateral guidance path on 23 has an early path with a disto-lateral vector to accommodate the lax right TMJ associated with his bruxism. The mid-path has a vertical vector and final path an anterior vector to complete a fully protective left lateral path. The protrusive path illustrates bilateral protrusive ramps on 11 and 21 teeth which created a protective sagittal mandibular vector. Bilateral protrusive ramps and lateral guiding or restrictive ridge Fig. 6 Extreme habit of tensing the platysma which results in a damaging mandibular retrusion which results in a retrusive vector towards the TMJs, with symptoms including digastric and sub-lingual muscle pains, TMJ pains and clicking discs. The patient was instructed to desist from doing this habit and habit re-training involved creating a new habit of ‘lips together teeth apart’. Fig. 7 The left view illustrates a tongue pressing habit which results in a damaging mandibular retrusion which results in a retrusive vector towards the TMJs. In the right view illustrates a tongue biting habit with deep indentations in the lateral margins. Symptoms included temporalis, masseter and TMJ pains. The recommended new habit was to ‘place the tongue flat on the floor of the mouth, without muscular pressure on the teeth, like a stingray does on the floor of the ocean’.
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