anatomical considerations - primary impressions

Question 1

How are complete dentures made?

Answer 1

Denture construction

Denture provision

Question 2

How are dentures constructed?

Answer 2

Primary and secondary impressions during visits 1 and 2

Registration and wax try-in during visits 3 and 4

Question 3

What happens during denture construction?

Answer 3

Shape of edentulous ridges recorded
Correct placement of teeth established - inter-ridge relationships
Wax template made
Template converted to acrylic denture

Question 5

How is the correct placement of teeth established?

Answer 5

Occlusal registration blocks are placed in situ

They are mounted in centric relation on articulator

Question 6

How are dentures provided?

Answer 6

Fit stage and review during visits 5 and 6

6-12 months post fit review

Question 7

Where should the dentures extend to?

Answer 7

1-2mm in front of the fovae palatini

Question 8

What are the fovae palatini?

Answer 8

Two small indentations at the junction at the hard and soft palate

Question 9

What is denture candidiasis?

Answer 9

Red and speckled palate often due to wearing dentures at night

Question 10

What are the hamular notches?

Answer 10

Formed at junction of maxilla and hamular process of the sphenoid bone

Question 11

Where should the back of the maxillary dentures go on the lateral sides?

Answer 11

Hamular notches

Question 12

What happens if you don’t mold the hamular notches properly?

Answer 12

May lead to soreness and loss of retention

Question 13

What structures need to be molded properly?

Answer 13

Hamular notches
Prominent frenae
Full depth of labial and buccal sulci

Question 14

What is the relevance of the middle frenum?

Answer 14

Key reference point for impression taking

Question 15

What impact would a shallower sulcus have on a denture?

Answer 15

More lateral movement

Question 16

What is the relevance of the large frenae in the canine region?

Answer 16

Insertion into crest of ridge may reduce retention of maxillary denture

Question 17

What is the relevance of the incisive papilla?

Answer 17

Key reference point for maxillary incisors

Mean distance between IP and incisor is ~12mm

Question 18

What is the relevance of the retromolar pads?

Answer 18

Key reference point for posterior border of mandibular border
Denture should cover just over half of this

Question 19

What is the relevance of the mylohyoid ridge?

Answer 19

Key reference point for lingual border of mandibular denture

Question 20

What is the relevance of the external oblique ridge?

Answer 20

Key reference point for buccal border of mandibular denture

Question 21

What is the relevance of the lingual gingival remnant?

Answer 21

Usually on newly edentulous patients

Indicates where to place teeth

Question 22

What is the relevance of the lingual frenum?

Answer 22

Key reference point

Move tongue side to side and forward during impressions

Question 23

What is the relevance of the genial tubercles?

Answer 23

Bony extentions

If denture rocks on this as jaw resorbs and ridge gets smaller may be traumatic

Question 24

What is the relevance of the insertion of mentalis?

Answer 24

May be uncomfortable for dentures to rock on as jaw resorbs and ridge gets smaller

Question 25

What is the relevance of the mental foramen?

Answer 25

Mental nerve may get trapped as the jaw resorbs and ridge gets smaller
Shooting pains

Question 26

How is informed consent gained?

Answer 26

``` Explain who you are Carry out initial assessment for notes Diagnosis and prognosis Explain no of visits and treatment Propose changes, benefits and risks Ask if they understand and if any Qs Clearly document ```

Question 27

What is the initial assessment?

Answer 27

Reason for attending Med/social/dental history Observations from oral examination

Question 28

What should be said on subsequent visits?

Answer 28

Explain today’s treatment Ask if understood and any Qs Reestablish objectives of treatment Write up notes

Question 29

What are the ideal properties of impression materials?

Answer 29

Accuracy Resolution Dimensional stability Rigid or elastic

Question 30

Why do we use alginate?

Answer 30

Simple, cheap, bonded to tray with adhesive, viscous during placement, elastic when set HOWEVER, unstable if not cast up quickly

Question 31

What is the problem with stock trays?

Answer 31

Impression material may debond if large undercuts present

Question 32

How do you select your stock tray?

Answer 32

If the medium tray doesn’t fit, use a small or large | Use callipers to take inter hamular notch width of patients old dentures

Question 33

Why might a greenstick be used?

Answer 33

If the stock tray doesn’t fit properly, they can be adapted with this

Question 34

How do you use greenstick?

Answer 34

Very hot water softens this and it’s good to add to retromolar pads and palate

Question 35

Why and how do you apply adhesive to the tray?

Answer 35

To hold the material in the tray when removing | Apply copiously and leave for 5 mins before impression

Question 36

Where do you stand when taking an upper impression?

Answer 36

Behind right shoulder | Maxilla at your elbow

Question 37

Where do you stand when taking a lower impression?

Answer 37

In front | Mandible at your elbow

Question 38

What should be happening as the impression material is setting?

Answer 38

Apply traction to the cheeks | Get the patient to do functional movements with lips and cheeks

Question 39

How do you get finer detail on the impression?

Answer 39

Trim peripheral excess so 1-2mm short of functional sulcus depth Relieve frenae

Question 40

What should you do if the alginate debonds?

Answer 40

Retake

Question 41

How do you mark your impression as an indication for the special trays?

Answer 41

Use an indelible pencil to mark 1-2mm inside the depth of the periphery

Question 42

Why might old good dentures be useful?

Answer 42

Provide an alginate for lab to cast up Gives indication of how denture looks Helps to select mold of teeth Shows diastimer or crossover of teeth

Question 43

What instructions should you give to the lab?

Answer 43

``` What material for second impression What tray is needed Eg. Non perforated close fitting special tray for zinc oxide Patient sticker Date and signature ```

Question 44

How do you reduce the risk of cross infection?

Answer 44

Immerse the impressions in perform for 10 mins | Must be clearly documented

Question 45

How are the impressions made?

Answer 45

Stock tray for an alginate primary | Special tray for zinc oxide-eugenol secondary