CATEGORY 72 AUSTRALASIAN DENTIST CLINICAL Introduction In 2001, Darveniza bio-designed occlusal schemes by modifying classic tooth anatomy to restorative anatomical shapes required to create ‘Full Occlusal Protection’ (Darveniza 2001) and discussed the term hinge occlusion (Darveniza 2001). An ‘ideal hinge occlusion occurs when reproducible hinging of the TMJs correlates with bilateral simultaneous contact of teeth (without incline-to-incline contacts posteriorly) in centric relation’ (Darveniza 2001). The author uses the term hinge occlusion or hinge bite to describe the existing occlusal scheme present when a patient makes first contact/contacts at the end of the hinging arc of closure in centric relation. ‘Full Occlusal Therapy’ can be defined as sequential treatment performed in three stages, as needed: Stage 1 a ‘Fully Protective Occlusal Splint’ with a minimum of four splint adjustments over a minimum threemonth period (‘Formal Fully Protective Occlusal Splint Therapy’) (Darveniza 2022, Darveniza 2022, Darveniza 2022); Stage 2 major and fine tune occlusal equilibration appointments; and Stage 3 bio-designing molar or anterior guidance. Full occlusal therapy also encompasses during these stages concurrent ‘full counselling’ targeting occluso-mandibular habits, improving sleep posture and optimum body posture (Darveniza 2023, Darveniza 2023). The author has used ‘full occlusal therapy’ as the starting point for conservative management of TMDs (Dworkin and LeResche 1992) since 1981 and bio-designing lateral guidance/ restriction for brachyfacial and normal skeletal types since 1988 (Darveniza 2001). For a dolichofacial patient, the author first used molar rise in 1991 to bio-design a lateral occlusion. Molar guidance for dolichofacial patients can be defined as: 1. the coupling of ipsilateral molars in lateral path to restrict disto-horizontal mandibular movements while creating vertico-lateral mandibular movement over a 2.5-3.5 mm long lateral path; 2. the coupling of bilateral molars in early to mid-protrusive path over approximately a 3 mm long path followed, where possible, by the coupling of central incisors from mid to final path to create sagittal mandibular movement; 3. patients with a large anterior overjet and open bite can only achieve sagittal directed protrusive tooth guidance with the molars in early path and with the central incisors in final path as tooth contact will be absent in mid protrusive path and 4. molar guidance usually involves the first or second ipsilateral molars or if required contralateral molars. The use of first molar guidance instead of canine guidance for occlusal splints has been studied with EMG and the course of symptomatology (Graham 1986, Graham 1988, Rugh 1989). The results indicated decreased muscle activity and symptoms in both lateral guidance groups and with no significant difference between groups. There were no similar studies available for molar guidance of teeth relating to biodesigning lateral and protrusive guidance on molars for occlusal reconstruction of TMD patients. This paper describes the design elements required to create ‘full occlusal protection’ for molar guidance in dolichofacial TMD patients illustrated with three case studies who underwent ‘full occlusal therapy’. Materials and methods Examination Complete oral examination of TMD patients was carried out in parallel with two occlusal orientated papers by Egan (Egan 1982) and Rieder (Rieder 1975). The diagnostic imaging examination included an initial radiographic evaluation of TMJ’s, teeth and jaws with an orthopantomogram followed by lateral transcranial radiographs, arthrograms, and MRI of the TMJ’s as indicated. All comments, including colloquial ones, made by the patient were recorded. Examination and palpation of muscles and joints including digital verification externally and or via the external auditory canal by the patient and/or operator. Occluso-mandibular analysis Occluso-mandibular analysis can be defined as the visual inspection of contiguous contacting of teeth during mandibular movements in hinge occlusion and the full range of excursive movements (Darveniza 2023,Darveniza 2022). Intraoral examination of a dolichofacial TMD patient included an occluso-mandibular analysis which involved determining the level of protection or the presence of unprotected occlusal schemes in hinge, protrusive and lateral occlusion according to Darveniza (Darveniza 2001). Hinge occlusion (Darveniza 2001) or the first contact/contacts of teeth in centric relation was considered as protective when bilateral simultaneous contacts (without posterior incline contacts) occurred without lateral or posterior/anterior mandibular vectors. In protrusive and lateral occlusion, the early, mid, and final mandibular paths were examined for contiguous contact and mandibular vectors. Protrusive occlusion was considered fully protective when tooth contacts bilaterally guide the mandible in protrusion in early, mid, and final paths with a sagittal mandibular vector (Darveniza 2001). For a dolichofacial patient, the goal was to have a lower molar buccal cusp guide from early to mid-path on a protrusive ramp located on the corresponding upper molar and in a bilateral sagittal manner. Ideally, mid to final mandibular movement continued by engaging protrusive ramps on the palatal surfaces of the upper central incisors (bilateral and sagittal) ending at edge to edge on all central incisors. A lateral occlusion was considered protective when opposing molars engaged with a vertico-lateral vector (molar rise) over a small 2.5-3.5 mm mandibular path. This involved the lower buccal cusp moving laterally from the upper molar centric platform (Darveniza 2001) located in the central groove or marginal ridge region. This lower buccal cusp traversed laterally and vertically downwards while engaging the palatal side of the upper buccal cusp to end at edge to edge with the corresponding upper buccal cusp. The mandibular vectors for early, mid, and final paths in lateral occlusion were recorded. The destructive lateral vectors included horizonto-lateral, distohorizontal, and disto-vertical mandibular movements while the protective vector Bio-designing molar guidance for dolichofacial TMD patients with case studies By Dr. Michael Darveniza MDSc PhD (Qld) FRACDS, Prosthodontist: Lismore, New South Wales.
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