د. اسماء

Maxilla-mandibular relationship of removable partial denture

Establishment of a satisfactory occlusion for the removable partial denture patient should include the following:
(1) analysis of the existing occlusion.
(2) correction of existing occlusal disharmony.
(3) recording of centric relation or an adjusted centric occlusion.
(4) harmonizing of eccentric jaw movements for a functional eccentric occlusion.
(5) correction of occlusal discrepancies created by the fit of the framework and during processing of the removable partial denture.
Objective of recording jaw relation:

1-To establish and maintain a harmonious relationship with all oral structures and to provide a masticatory apparatus that is efficient and esthetically acceptable.

2-To ensure that all the effects of occlusal loading be distributed as evenly as possible to all supporting structures capable of receiving the force.

3-To best control the undesirable effects of rotational or torquing forces on the prosthesis

4-To prevent any deflective contacts of the teeth during centric or eccentric closures as these can produce pathological changes in the supportive structures or in the neuromuscular mechanism that controls mandibular movement.

Desirable occlusal (‘contact relationship for removable partial dentures):

Following occlusal arrangements - harmonious occlusal relationship of removable partial dentures are as follow:
1. For Kennedy class I mandibular partial denture. opposing completely edentulous maxilla. Balanced occlusion (working balancing and protrusive contacts of the posterior teeth. with light contact of the anterior teeth )
2. When maxillary Kennedy class I removable partial denture opposing mandibular class I partial denture working and balancing sides contact should be formulated to minimize tipping of maxillary partial denture and broadly distribute the forces.
3. For mandibular class I partial denture opposed by natural dentition. Simultaneous. working side contact only should be formulated.
4. For Kennedy class II mandibular. or maxillary partial dentures only working side contacts should be formulated.
5. For class IV maxillary removable partial denture. opposing natural dentition. contact of the opposing anterior teeth in centric occlusion is desirable to prevent a continuous eruption of the mandibular‘ incisors. Contact of the opposing teeth in eccentric position should be avoided to prevent overloading of maxillary arch and the formation of flabby tissue.
6. For Kennedy class III partial ‘denture. opposing natural dentition contact to the posterior teeth during functional movement is not desirable. since stability of the denture is maintained by direct retainers.
CONCLUSION


 The balanced occlusion is the most important factor for the retention of the prosthesis.
 The occlusion must be evaluate before the prosthesis fabrication start.
 Preprosthetic mouth preparation must be done for better occlusion reproduction.  Proper method to be used for the record of correct occusion.
imbalance occlusion is the main cause of retention loss of the prosthesis.