In dentistry, the neutral zone refers to that space in the

oral cavity In animal anatomy, the mouth, also known as the oral cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is also the cavity lying at the upper end of the alimentary canal, bounded on t ...

where the forces exerted by the musculature of the

tongue The tongue is a muscular organ in the mouth of a typical tetrapod. It manipulates food for mastication and swallowing as part of the digestive process, and is the primary organ of taste. The tongue's upper surface (dorsum) is covered by taste ...

are equal and balanced with the forces exerted by the

buccinator muscle The buccinator () is a thin quadrilateral muscle occupying the interval between the maxilla and the mandible at the side of the face. It forms the anterior part of the cheek or the lateral wall of the oral cavity.Illustrated Anatomy of the Head ...

of the cheek laterally and the

orbicularis oris muscle In human anatomy, the orbicularis oris muscle is a complex of muscles in the lips that encircles the mouth. It is a sphincter, or circular muscle, but it is actually composed of four independent quadrants that interlace and give only an appearance ...

anteriorly. 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 Prosthodontics, also known as dental prosthetics or prosthetic dentistry, is the area of dentistry that focuses on dental prostheses. It is one of 12 dental specialties recognized by the American Dental Association (ADA), Royal College of Surgeo ...

, 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. 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

{{reflist Dentistry