Occlusal Rim.pptx 35373g

OCCLUSAL RIM

Difficulties in Guiding Mandible to Centric Relation Position 1. Biologic = caused by habitual eccentric jaw positions adopted by patients to accommodate to malocclusion. 2. Psychological 3. Mechanical = It is essential that the denture bases on which the occlusal rims is made fit perfectly and do not interfere with each other. Failure of adaptation of denture base to the tissue surface may result in unevenly distributed pressure on the underlying resilient tissue leading to discrepancy in jaw relation recording.

Various Methods of Recording Centric Relation 1. Functional (Chew-in) methods a. Needle house method. b. Patterson’s method. c. Meyer’s method.

2. Excursive methods (Graphic method) a. Intraoral tracing. [Intraoral balancer (Hanau co.),S-Agothic arch tracer(Tokyo shikasha)] b. Extra-oral tracing. [Height Tracer (Hanau co.) 3. Tactile or interocclusal check records. 4. Terminal hinge axis method 5. Other methods. a. Heating the surface of one of the rims. b. Softened wax placed over the occlusal surfaces of the occlusal rim. c. Soft cones of wax placed on the lower denture trial bases.

Interocclusal check records: It is particularly indicated in situation of:

1. Abnormally related jaws. 2. Excessively displaceable ing tissues. 3. Large awkward tongue. 4. Uncontrollable or abnormal mandibular movements. 5. To check the occlusion of teeth in trial dentures.

Inter-occlusal record: (A) Nick and notch in the maxillary occlusal rim (B) Trough in the mandibular occlusal rim

Inter-occlusal centric relation record

Requirements of Completed Record Base 1. It should be rigid, accurate and stable. 2. The borders should be developed like borders of finished denture. 3. The surface that s lips, cheeks and tongue should be smooth and polished. 4. The slopes of the base on labial and buccal sides and in the crest area should be thin for placement of teeth. 5. The non-anatomical surface should be smooth for the comfort of the patient during jaw relationrecording procedure.

Heat cure record base: (A) Wax pattern (B) Processing (C) Processed record base

Occlusal Rim /Record Rim occlusal rims are prepared using standard dimensions. Most patients require modifications in the occlusal rim to suit the patient. These alterations should be done before recording the jaw relation.

1. 2. 3. 4. 5.

The occlusal rims are inserted into the patient’s mouth and the following factors are checked:

Lip and labial fullness Overjet Cheek and buccal fullness Level of the occlusal plane Orientation of plane of occlusion

1. Lip and labial fullness The occlusal rim should provide adequate lip . Inadequate or excessive labial will seriously affect the aesthetics of the denture.

2. Overjet The incisal edge of the maxillary occlusal rim should be around 2 mm in front of the incisal edge of the mandibular occlusal rim.

Normal horizontal overlap

Edge to edge relation in class III cases

Excessive overjet in class II cases

3. Cheek and buccal fullness The occlusal rims should be designed to be within the neutral zone. This is important because if the occlusal rims have excess wax buccally, the buccal musculature will produce displacement of the occlusal rim. Apart from that, the teeth arranged buccally produce frequent cheek biting.

4. Level of the occlusal plane

• The occlusal plane should be located at the midpoint of the interarch distance. The upper occlusal rim should be reduced upto or 2 mm below the level of the upper lip during speech • Posteriorly it should be two-third the height of the retromolar pad.

5. Orientation of plane of occlusion The plane of the occlusal rim should be parallel to the plane of the maxilla. It should not be confused with the orientation of the occlusal rim (discussed in orientation jaw relation), which denotes the orientation of the maxilla to the base of the skull.

The ideal dimension of maxillary occlusion rim: 1. Height A. Anterior—24 mm (from the deepest area of the sulcus) B. Posterior—21 mm (in the first molar region)

The ideal dimension of mandibular occlusion rim:

1. Height A. Anterior—20 mm (from the deepest area of the sulcus) B. Posterior—approximately 18 mm (height of anterior 2/3rd of retro molar pad) 2. Width of occlusal rim (maxillary and mandibular) Anterior—6 mm Posterior—8 mm

Mandibular occlusal plane in relation to the anterior 2/3rd of the retromolar pad