In
dentistry
Dentistry, also known as dental medicine and oral medicine, is the branch of medicine focused on the teeth, gums, and mouth. It consists of the study, diagnosis, prevention, management, and treatment of diseases, disorders, and conditions o ...
, the neutral zone refers to that space in the
oral cavity where the forces exerted by the musculature of the
tongue are equal and balanced with the forces exerted by the
buccinator muscle of the cheek
laterally and the
orbicularis oris muscle anterior
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
ly.
In other words, it is the ''potential space'' between the lips and cheeks on one side and the tongue on the other; where the ''forces'' between the two are ''equal''. Other synonyms include: zone of equilibrium, zone of minimal conflict, potential denture space and dead space. It is in this zone that the natural dentition lie, and this is where artificial teeth of complete dentures should be positioned. Complete dentures that are constructed in this way exhibit ''enhanced stability, retention and comfort''.
The neutral zone is an important concept in
prosthodontics, because prosthetic teeth generally must conform to the horizontal position determined by the neutral zone. Prostheses which set teeth outside this zone risk problems such as discomfort, cheek or tongue biting, and instability of the denture.
The neutral zone is also important in
orthodontics
Orthodontics is a dentistry specialty that addresses the diagnosis, prevention, management, and correction of mal-positioned teeth and jaws, and misaligned bite patterns. It may also address the modification of facial growth, known as dentofacial ...
. Moving teeth outside of this zone means that the muscular forces on the teeth will be out of balance in one direction, and tend to be more likely to relapse to their original position.
Indications
The neutral zone technique is indicated in cases where there has been:
* Extensively resorbed mandibular ridge (minimal bone available to support a denture)
* Patients with neurological conditions
* Patients who have previously had partial
glossectomies, mandibular resection and/or motor nerve damage to the tongue
* Where dental implants are not feasible
Advantages and Disadvantages
Advantages of constructing a denture within the neutral zone include:
* ''Improved stability and retention'' of complete dentures (particularly lower complete dentures)
* Correct positioning of posterior artificial teeth allows for ''sufficient tongue space''
* ''Reduced food trapping''
* ''Improved aesthetics'' due to facial support
Disadvantages include:
* Increased clinical time
* Increased laboratory costs
References
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Dentistry