Surveying and Denture design principles

Question 1

What is the function of the analysing rod?

Answer 1

analyses tooth and tissue undercuts and determines the path of insertion for the denture

Question 2

What is the function of the graphite marker?

Answer 2

Scribe tooth and tissue undercuts on the model with the graphite marker

Question 3

what is the function of the undercut gauge?

Answer 3

measure desired amount of undercut for the clasp material needed

Question 4

What is the function of the chisel?

Answer 4

used to trim the blocked out undercut areas on the model

Question 5

What tool is used first in surveying for denture design?

Answer 5

The analysing rod is used first to study tooth and tissue undercuts and establish a oath of insertion for the denture

Question 6

How can you tell what area of the tooth is undercut and what is non undercut?

Answer 6

Undercut area - there is space between the analysing rod and tooth
no space = no undercut area

Question 7

Once the line of insertion is decided, what is done to allow the model to be put back on the surveyor at the same angle at a later date?

Answer 7

lines are drawn on the sides and back of the model using the analysing rod

Question 8

After the analysing rod, what tool is used next?

Answer 8

the graphite marker is used next - to establish the broadest part of the tooth and the undercut and non undercut area of the tooth

Question 9

what side of the graphite marker tip should contact the tooth

Answer 9

the longer side

Question 10

what area is above and below the survey line ?

Answer 10

area above =

Question 11

What information is gained for a survey line?

Answer 11

1. indicates the undercut area on a tooth and non undercut area
2. the type of survey line indicates what retentive component can be used to help retain the denture

Question 12

What type of clasp would be used for a diaganal survey line?

Answer 12

Occlusally approaching clasp
(stainless steel or cobalt chrome)

The clasp should taper towards the retentive tip of the clasp
The final third of the clasp is below the survey line and will flex over the tooth and into the undercut area

Question 13

What type of clasp would be used for a high survey line?

Answer 13

Gingivally approaching clasp is used, as two thirds of an occlusally approaching clasp cannot approach from above the survey line.
Positioned on or below the survey line.

Question 14

What type of clasp would be used for a low survey line?

Answer 14

Gingivally approaching clasp can be used and would be less visible than an occlusally approaching clasp may be positioned mesial, central or distal.
Distal nay be more hidden so better aesthetically and is positioned on or below th esurvey line

Question 15

What size of undercut can a cobalt chrome clasp utilise?

Answer 15

up to 0.25mm - brittle material

Question 16

What size of undercut can a stainless steel clasp utilise?

Answer 16

up to 0.5mm - more flexible than cobalt chrome so can engage a deeper undercut

Question 17

What size of undercut can a gold clasp utilise?

Answer 17

up to 0.75mm - more flexible than both steel and cobalt chrome

Question 18

How to measure an undercut?

Answer 18

Hold an undercut gauge barrel against the tooth and draw upwards until the ledge touches the tooth - this is the point where the terminal third of the clasp will finish

Question 19

What are the 4 component parts of dentures?

Answer 19

1. PMMA (poly-methyl-methacrylate-acrylic) plate = major connector
2. Saddle areas - consists of the replacement teeth and flange extension
3. Clasps - the clasps are the retentive component (stainless steel and cobalt chrome)
4. Occlusal rests - provide support for dentures

Question 20

What are the 3 functions of occlusal rests?

Answer 20

1. provide support for denture
2. directs occlusal load down the long axis of the teeth
3. can provide indirect retention

Question 21

What lower major connector is more comfortable and stronger (although more expensive) - PMMA or cobalt chrome?

Answer 21

Cobalt chrome plate

Question 22

what is the minimum size space from the sulcus depth to the gingival margin required to prescribe a lingual bar?

Answer 22

7mm

Question 23

what are the benefits of using a lingual bar to a cobalt chrome plate?

Answer 23

It covers less gingival margins than the cobalt chrome plate and may also be used when there is spacing between anterior teeth so the connector is not visible through the tooth spaces

Question 24

To use a dental bar what do you need to ensure?

Answer 24

• there is no spacing between anterior teeth
• the dental bar required a minimum total crown height of 9mm for this connector to be used (5mm bar width with 2mm clearance from gingival margin and 2mm clearance from incisal tip)

Question 25

What type of clasp is this?

Answer 25

a ring clasp cobalt chrome with occlusal rest

Question 26

What type of clasp is this?

Answer 26

Occlusally approaching circumferential clasp, cobalt chrome with occlusal rest

Question 27

what type of clasp is this?

Answer 27

three arm clasp cobalt chrome with occlusal rest

Question 28

What type of clasp is this?

Answer 28

stainless steel occlusally approaching clasp

Question 29

What type of clasp is this?

Answer 29

gold gingivally approaching clasp

Question 30

What type of clasp is this?

Answer 30

Dental.d.acetyl resin clasp

Question 31

What upper major connector is more hygienic and why - PMMA or cobalt chrome?

Answer 31

cobalt chrome designs are thinner in section than the PMMA and can free up the gingival margins so are more hygienic and comfortable for the patient

Question 32

What is the typical width of a palatal bar of an upper major connector?

Answer 32

7 and 12 mm

Question 33

how is the chisel used when designing a denture?

Answer 33

1. undercut areas are filled using plaster
2. plaster is chiselled up to the tooth whilst on the surveyor at the desired path of insertion for the denture
3. the ensures when injecting the PMMA into the mould it now cannot enter the undercut areas that were present