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Note the
black lines starting at the cuspid areas and extending
distally following the crest of the lower ridge. Dentistry
has taught that the buccal cusp be placed over the crest
of the lower ridge when positioning the posterior teeth |
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For most patients
this is OK, but for some it may position the lingual
cusp so far lingually that it creates undercuts the
tongue can get under. The
posterior teeth on this setup need to be moved bucally
to remove the undercut created by the teeth position.
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Note the first and second
molars set on this baseplate. The 4 molar teeth’s
buccal cusps are over the crest of the ridge, the lingual
cusps of the molar teeth have created undercuts large
enough for the tongue to unseat the lower denture during
talking, swallowing and when the patient is chewing
food. |
|
Note on the these teeth
the lingual cusps are in line with the crest of the
ridge. There are no lingual undercuts. The tongue would
not be restricted on this case by any of the posterior
teeth. |
|
When it’s necessary to position
the lingual cusp of the lower teeth over the crest
of the ridge. To eliminate the undercut we must be
concerned about cheek biting when setting the upper
teeth.
Setting the upper teeth in a cross
bite position, when it is necessary, will solve cheek
biting problems. Cross bite set ups rarely cause problems
for the patient. |
|
A.
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The mandibular neutral
zone is an area where the lower teeth can be positioned
between the tongue and cheek without infringing on the
tongue. |
| B.
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The maxillary neutral zone is an area
where the upper teeth are positioned to occlude with
the lower teeth between the tongue and cheek without
infringing on the cheek. |
| C. |
Setting teeth in the
neutral zone position will assist the denture patient
to be more comfortable wearing dentures. |
| I contend
when we position lower teeth that don't capture the
patient’s tongue, and then position the upper
teeth in occlusal contact with the lower that won’t
cause cheek biting. We have set the teeth in a neutral
zone position for the patient. |
