Lower Denture Checking for Extension
- The buccal and labial periphery:
- Hold the denture in place with light pressure on the occlusal surfaces and move the cheek on one side upwards and inwards, if the denture rises from the ridge. It is over-extended and needs trimming.
- The shape of the buccal aspect of the denture: A gentle convexity in the molar region and concave in the premolar region.
- The lingual periphery:
Hold the denture in place with light pressure and ask the patient:- to protrude his tongue sufficiently to moisten his lips.
- to put the tip of his tongue up to the back of his palate. If in any of these actions the denture
lifts, it is over-extended and needs trimming.
- Posterior extension:
- The heels of the lower denture are extended as high up the ascending ramus of the mandible.
- Under-extension:
- If the denture is found to be under-extended in any part of the periphery, an inaccuracy in the impression has taken place which must be retaken.
Lower Denture Stability
After applying pressure in the premolar and molar regions of each side alternately, the pressure on one side should not tilt the denture on the opposite side.
Lower Denture Tongue Space
- The ideal place for artificial teeth placement is the neutral zone. The area in the mouth where the forces of the tongue pressing outward are neutralized by the forces of lips and cheeks pressing inward.
- If the tongue is cramped, the denture will begin to rise immediately when the tongue is raised.
Lower Denture The causes of the lack of tongue space are:
- Posterior teeth are set inside the ridge.
- Molar teeth are too broad buccolingually.
- Molar teeth leaning inwards.
- Setting the upper teeth over the ridge almost invariably leads to the occluding lower teeth lying too far lingually.
Height of the Occlusal Plane
Upper Denture
Height of the Occlusal Plane Checking for Extension
Checking peripheral extension in buccal and labial aspects are same as checking in lower dentures.
Height of the Occlusal Plane Stability
Same as for checking in lower dentures.
Height of the Occlusal Plane Retention
- Retention is checked by seating the denture with a finger on the vault of the palate and then attempting to remove the denture at right angles to the occlusal plane.
- Load is applied upwards and outwards in one canine region to check the retentive force in the contralateral corner of the denture as the tuberosity vestibular space and pterygomaxillary notch. Check the other side in the same way.
Both Dentures together
Both Dentures together Anterior plane:
- Check the midline
- The shape of the teeth
- Size of the teeth
- Shade and blend of the teeth
- Profile and lip form.
Both Dentures together Posteriorly:
- Check centric relation:
- Hold the lower denture in position on the ridge and ask the patient to relax, and instruct to close the patient’s back teeth gently and maintain them in occlusion. If the registration is accurate, the teeth will interdigitate in the mouth in exactly the same manner as they do on the articulator.
- Vertical height:
- Ask the patient to relax with the lips closed. While observing the point of the chin, ask the patient to close the teeth together; the chin should move upwards, a small definite amount. Counter-check with the phonetic test as Silverman’s closest speaking test.
- Evenness of occlusal contact:
- If the horizontal and vertical relationships are correct, the occluding teeth should occlude evenly and with equally distributed pressure all around.
- Uneven contacts are due to:
- Pressure on the blocks was heavier on one side than the other when the records were made.
- Sealing errors in the casts and blocks together when mounting them on the articulator.
- Warpage of the base plates.
- Balanced occlusion and articulation:
- In the mouth check for evenness of occlusal pressure in the retruded contact position with Mylar tape and then test for occlusal balance with gentle lateral and protrusive movements. With the teeth in a working position of occlusion, insert a thin blade between the teeth on the balancing side and attempt to separate them.
The thin blade should not separate easily. Minor errors of cuspal interference are best left until the dentures have been finished and fitted.
Leave a Reply