Neutral zone impression

Question 1

Neutral zone?

Answer 1

the potential space between the lips and cheeks on one side and the tongue on the other;

that area or position where the forces between the tongue and cheeks or lips are equal

where the denture teeth can avoid being dislodged by normal oral functions

can be used to help define tooth position and/or shape of polished surfaces

Question 2

Where is the denture sitting?

Answer 2

neutral zone

Question 3

For complete stability, where should the prosthetic teeth be arranged?

Answer 3

within the neutral zone

Question 4

Techniques for positioning of denture teeth?

Answer 4

biometric guides to replicate natural tooth position

conventional shaping of wax rim

copy denture

NZ (neutral zone) technique

Question 5

conventional zone technique?

Answer 5

produces dentures of good stability

where there is a favourable ridge

Question 6

when to use neutral zone technique?

Answer 6

resevered for pt for proven instability

has not been able to be rectified…

resorbed ridges
enlarged tongue
poor facio-structural control
Parkinson’s/stroke
facial reconstructive structure

Question 7

conventional technique used on pt with resorbed ridges?

Answer 7

poor denture stability

Question 8

good ridges, use what technique?

Answer 8

conventional dentures

Question 9

NZ technique reserved for what teeth?

Answer 9

lower anterior

Question 10

what happens to the ridge with tooth loss?

Answer 10

degenerative changes take place and ridge flattens

Question 11

what happens with flattened ridge?

Answer 11

has a reduced ability to resist lateral displacing forces

Question 12

why is image 2 a problem?

Answer 12

second image has a larger distance between the ridge and occlusal surface

resulting in greater instability

consequently retention and stability of denture become more dependent on the correct positioning of teeth and the contours of the external/polished surfaces of denture

Question 13

how to seat the lower denture?

Answer 13

more dependent on the correct positioning of teeth and the contours of the external/polished surfaces of denture

peri denture muscular should act to seat the denture rather than displace it

Question 14

tongue widens after tooth loss?

Answer 14

lateral spread of the tongue

Question 15

what is occurring here due to bone resorption?

Answer 15

insertion of the circum-oral musculature come to light superficially to the denture bearing area

causing denture instability

Question 16

effect of age on complete dentures?

Answer 16

loss of facial tonicity

diminished capacity for successful neuromusculture adaptation

Question 17

the age at which people become edentate is increasing

relevance to clinical tx?

Answer 17

poor denture bearing tissues

poor capacity for adaptation

poor tolerance of complete dentures impacts of quality of life indices an nutrition

Question 18

what is the preferred minimum tx option for stabilizing lower complete dentures?

Answer 18

2 mandibular implants

Question 19

why 2 mandibular implants?

Answer 19

stabilization

increase function

decrease pain

increase pt quality of life compared with conventional dentures

Question 20

why would a pt no want mandibular implants?

Answer 20

fear of pain

post op complications

social embarrassment

financial resources

not not perceive the necessity

Question 21

if pt does not want implant to stabilize denture, what is the other option?

Answer 21

prosthesis manufactured according to NZ principles

Question 22

objectives of NZ?

Answer 22

define the position of the lower anterior teeth so they are in equilibrium between opposing muscular forces

sculpt the polished surface so that the forces exerted by the muscles will tend to stabilise the denture rather than unseat it

Question 23

CONSORT?

Answer 23

guidelines for clinical trials - gold standard is CONSORT

Question 24

guidelines for consort?

Answer 24

sample size calculation

randomisations

blinding

statistical methods

limitations

external validity

Question 25

NZ vs conventional?

Answer 25

pts prefer NZ dentures

pts with well formed ridges prefer conventional dentures

better masticatory performance with conventional

‘muscular’ fixation of dentures better with NZ dentures

conventional dentures have better retention

Question 26

where does most evidence for dentures come from?

Answer 26

randomised control trials rather than CONSORT

Question 27

1) technique to record labio-lingual position of lower anterior denture teeth?

Answer 27

1) NZ tray made on the working cast after the bite registration stage

occlusal stops incorporated
- can be made form green stick or fabricated in lab

2) try-in tray
- check stability, extension, comfort
- blocks and wires not outside of neutral zone

3) load with impression material
- pt performs sequence of mouth exercises

• make sounds

4) NV the wax try-in with teeth

Question 28

2) technique to define the shape of the polished surfaces?

Answer 28

define the polished surface

1) Vaseline added to teeth as separator

2) silicone impression material is added to the polished surface

3) pt asked to make movements to mould the polished surface

4) returned to lab
- lost wax technique for complete denture

5) NV = fit
- special care for stability

Question 29

impression material?

Answer 29

compo (green stick)

silicone

modified waxes

viscogel

Question 30

what is the neutral zone with regards to dentures?

Answer 30

the position of muscle balance an dis especially relevant to -/C

Question 31

when to use neutral zone?

Answer 31

for unstable -/C cases which cannot be managed by conventional means

Question 32

typical pt who benefits form NZ?

Answer 32

atrophic ridges

neurological conditions

post resection surgery

Question 33

preferred tx option over NZ?

Answer 33

implant supported over denture