LITMIR.BIZ

Скачать книгу

alt="image"/> The two most reliable signs of active bruxism are, however, scalloping of the lateral border of the tongue (Figure 3.12b) and ridging of the buccal cheek mucosa along the occlusal line (Figure 3.12c). These features are due to the soft tissues being thrust against the surfaces of the teeth during parafunction. Ridging of the cheek mucosa is occasionally severe enough to present clinically as frictional hyperkeratosis. Both scalloping of the tongue and ridging of the cheek mucosa usually disappear when the parafunction ceases.

Occlusal examination 1

      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

To examine all lateral excursions, patients are instructed to close lightly into centric occlusion and subsequently slowly execute maximum active right, left, and protrusive mandibular movements while maintaining contact between the mandibular and maxillary teeth (Figure 3.16).

Figure 3.16 Determination of anterior guidance.

      (M. Ziad Al‐Ani, Robin J.M. Gray.)

The anterior guidance in the mandible can be on the canine teeth, which is ideal because this means that the patient can move the mandible from side to side with immediate disclusion of the posterior teeth (Figure 3.17).

Figure 3.17 Canine guidance.

      (M. Ziad Al‐Ani, Robin J.M. Gray.)

      There can be group function where the canine, premolar, and molar teeth all contact during lateral excursion of the mandible. This is equally acceptable, preferably with the anterior contact being firmer than the posterior contact.

Posterior interferences

If posterior teeth ‘get in the way’ (interfere), this can be detected by immediate separation of the anterior teeth and guidance of the mandible is then transferred to the interfering tooth. It is thought that interferences, usually on the non‐working side (Figure 3.18a) but also on the working side (Figure 3.18b), can be responsible for initiating parafunction. Check for the presence of interferences up to maximum lateral excursions. Patients may parafunction with the mandible in very unlikely and extreme lateral positions, and this may not be clinically evident unless you are meticulous with your examination.

Figure 3.18 (a) Non‐working side interference; (b) working side interference.

      (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.)

Freedom in centric occlusion

Скачать книгу