In dentistry, 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 anteriorly.
[1][2] 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.
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.
Prostheses which set teeth outside this zone risk problems such as discomfort, cheek or tongue biting, and instability of the denture.