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5. Prosthodontic Instruments


Three types of jaw relationships will be discussed: centric jaw relationship, maxillo-temporomandibular joint relationship, and lateral and protrusive relationship.

a. Centric Jaw Relationship. When final casts have been obtained and occlusion rims or trial bases fabricated, the next procedure is to determine the correct positional relationship of the maxillary cast to the mandibular cast for setting the denture teeth and establishing occlusion. Determinations are usually made and recorded in the mouth by using occlusion rims and one of the following materials: modeling plastic, plaster of Paris, or softened wax. A needle point-tracer (the gothic arch tracer) may also be used for this record. (See figure 5-13.) The recordings and occlusion rims are then transferred to the casts for mounting on the articulator.

b. Maxillo-Temporomandibular Joint Relationships. The prostbodontist may also record the relationship existing between the maxillae and the opening and closing axis of the temporomandibular joint. This registration is used to mount the maxillary cast on the articulator in the same relationship to the hinge axis of the articulator as the patient's maxillae has to his temporomandibular joint. A face-bow registration is used to record this relation.

c. Lateral and Protrusive Relationships. Right and left lateral and protrusive positions of the mandible in relation to the maxillae may be registered by a needle point-tracing for transfer to an adjustable articulator.

NOTE: The shades and mold of denture teeth to be used are usually selected during this phase of complete denture fabrication.

Figure 5-13. Instruments and materials for jaw relationship registrations in complete denture fabrication.

David L. Heiserman, Editor

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Revised: June 06, 2015