3.11 (a) A stereo‐stethoscope used for listening to the temporomandibular joint. (b) Stereo‐stethoscope in use allowing auscultation and comparison of one TMJ with the other.
(M. Ziad Al‐Ani, Robin J.M. Gray.)
The apparatus provides a method of detecting TMJ sounds and determining whether they emanate from the right or left side or are bilateral. It should be remembered that it is sometimes extremely difficult to determine which side a click is coming from by listening with a stethoscope because of the ‘echo’ and reverberation across the bones of the skull from the contralateral side. In addition, auscultation permits the clinician to detect the frequently softer closing click that is sometimes difficult to detect on joint palpation alone.
For the diagnosis of disc displacement with reduction and to assist in determining a suitable treatment plan, it is important to determine whether the click can be eliminated by protrusion of the mandible. At the chair side, the patient is asked to protrude the mandible and then perform a series of opening and closing mouth movements, usually with the upper and lower incisors in an ‘edge‐to‐edge’ relationship. The click will be present during the first movement but, if the click is eliminated in subsequent movements in this protrusive mandibular position, the diagnosis of disc displacement with reduction is highly probable and it is likely that provision of a suitable splint design will reduce or eliminate the symptoms.
Crepitus
Crepitus is a crunching or grating sound that indicates degenerative joint disease. It can be heard with a stethoscope or, if severe, without when it may be readily audible to others. It can be present throughout the movement cycle or at any point in the cycle.
Signs of bruxism
Figure 3.12 (a) Attrition, (b) tongue scalloping, and (c) cheek ridging seen in patients who parafunction.
(M. Ziad Al‐Ani, Robin J.M. Gray.)
Dental sensitivity is a common symptom of active bruxism. The anterior teeth are often affected and this is frequently noticed on waking from sleep. Repeated tooth and/or restoration fracture is often also reported.
Occlusal examination
For the purposes of occlusal examination of a patient with a TMD, a straightforward examination technique can be employed. Further and more detailed examination will be necessary if it is determined that the occlusion is a major aetiological factor in the TMD or if restorative treatment is planned.
Centric occlusion and centric jaw relation
It is important to determine whether centric occlusion (the habitual bite) coincides with centric jaw relation (the patient's relaxed mandibular position). If these two jaw positions do not coincide (Figure 3.13), it is important to determine where the premature occlusal contact occurs at first tooth contact and what is the direction of the slide from the initial centric relation contact to the patient's habitual bite. If there is premature contact and a small slide from centric relation to centric occlusion, and if in the same sagittal plane, this is not thought to be as clinically significant as a marked lateral slide. The direction and magnitude of the slide are therefore important.
Figure 3.13 The difference between (a) centric relation and (b) centric occlusion
(From Gray RJ, Davies SJ, Quayle AA. A clinical approach to temporomandibular disorders. 4. Examination of the articulatory system: the Occlusion. Br Dent J 1994;177:63–68.)
Manipulation of the mandible to centric relation is a difficult technique to master because only very gentle pressure should be applied (Figure 3.14).
Figure 3.14 (a) Centric relation (CR) recording; (b) premature contact in CR. (c) Slide from CR to centric occlusion observed and recorded.
(M. Ziad Al‐Ani, Robin J.M. Gray.)
The objective is not for the clinician to override the patient's muscle force with his or her own. If manipulation to centric jaw relation is difficult, it is sometimes useful to put a small amount of softened green‐stick compound between the upper and lower incisor teeth and help the patient to gently tap into this. This often relaxes the muscles to a degree whereby passive manipulation of the mandible can be achieved. When performing this manoeuvre, it is useful to use thin articulating paper (Baush Occlusion Paper 40 μm) supported in paper holding forceps (Figure 3.15).
Figure 3.15 Paper‐holding forceps: blue for static occlusion; red for dynamic movements.
(M. Ziad Al‐Ani, Robin J.M. Gray.)
The first tooth contact is recorded using the articulating paper and the patient is then requested to squeeze the teeth together and any slide from centric jaw relation to centric occlusion is observed and recorded.
Anterior guidance
