Neutral zone technique formandibular complete

dentures

Dr. Tiba A. salman

The neutral zoneIs the area in themouth where duringfunction, the forces ofthe tongue pressingoutwards areneutralised by theforces of the cheeksand lips pressinginwards.

The aim is ‘tolocate that area inthe edentulousmouth where theteeth should bepositioned so thatthe forces exertedby the muscles will

stabilizetend tothe denture ratherthan unseat it’.

The relationship of the lower posterior teeth to thecheeks and tongue: (a) correct (b) incorrect.

Advantages

• Improved stability andretention

• Posterior teeth will becorrectly positionedallowing sufficient tonguespace

• Reduced food trappingadjacent to the molarteeth

• Good aesthetics due tofacial support.

INDICATIONS

High mentalis muscle attachmentSeverely atrophic mandibular ridge

INDICATIONS

Motor nerve damage to the tongueMandibular resections

Materials used for neutralzone impression

Many materials have been suggested for shapingthe neutral zone:

Modeling plastic impression compound. Green stick compound.

Materials used for neutral zoneimpression

Tissue conditioners andresilient lining materials.

soft modeling wax. Silicone rubber baseimpression material.

Neutral zone impression technique

The primary impression Secondary impressionResorbed mandibular ridge

A lower acrylic record base with metal spursacrylic shim to aid retention of the impression

material.

Neutral zone impression technique

Establishing the correct occlusal heightOcclusal pillars have been builtup in green stick to the correct

occlusal height

viscogel rim is moulded within the mouth.

A completed neutral zone impression

Functional recording of neutral zone

A plaster index used to locate theteeth to the neutral zone.

A plaster index is poured around the neutralzone impression.

A plaster index used to locate theteeth to the neutral zone.

Try-in stage

Finished and polished denture