Bds4 Tutorials

Question 1

What undercut is required for a colbalt chrome, gold and stainless steel clasp?

Answer 1

CoCr- 0.25mm
Gold- 0.5mm
SS- 0.75mm

Question 2

What are the common pathological conditions associated with wearing dentures?

Answer 2

Ulcers
Denture stomatitis
Angular cheilitis
Denture irritation hyperplasia
Flabby ridge
MRONJ/ ORN
Allergic reaction

Question 3

Where are ulcers common (in denture wearing pt)?

Answer 3

Lingual Frenum
Mylohyoid ridge
Undercut areas

Question 4

What does an ulcer on the alveolar ridge suggest?

Answer 4

Ulcer caused by occlusal trauma

Question 5

What does an ulcer on the periphery suggest?

Answer 5

Ulcer caused by extensions of denture

Question 6

What is the urgent referral pathway for ulcers?

Answer 6

A non healing ulcer despite adjustments / unexplained ulceration persisting for >3 weeks - phone maxfacs

Question 7

What is denture stomatitis?

Answer 7

Candida albicans colonisation (localised infection to the denture bearing area)
Often due to poor denture hygiene

Question 8

What is the management of denture stomatitis?

Answer 8

Denture hygiene advice - take out at night, clean with soft brush, steep overnight.
Just of nystatin
New denture if candida is within porous denture base

Consider underlying immune deficiency (opportunistic disease) eg diabetes, folate, Vit B12

Question 9

What is angular cheilitis?

Answer 9

A skin condition affecting the commisures of the lips- often due to overclosing (old and worn dentures/ decreased OVD)
Can be caused by staph aureus (dentate) or Candida albicans (edentulous)

Question 10

What is the management of angular cheilitis?

Answer 10

Anti fungal - miconazole cream 2% (interactions with warfarin)
If unresponsive to this- can treat with miconazole and hydrocortisone ointment

Question 11

What type of microorganisms is miconazole effective against?

Answer 11

Gram +ve cocci and candida

Question 12

What is the advantage to incorporating milled crowns into denture design?

Answer 12

Allows the incorporation of rest seats, guide planes and precision attachments
Also allows to plan for future need

Question 13

What type of denture is more protective of periodontal tissues?

Answer 13

Cobalt chrome rpd

Question 14

What could be a risk of providing no prosthetic replacement for a perio patient?

Answer 14

Lack of posterior support may increase mobility of remaining teeth and will result in lack of denture wearing experience (for future need)

Question 15

What impression techniques can be used to take impression with periodontally involved teeth?

Answer 15

Block out undercuts with tin foil/ red ribbon wax/ cotton pledgets and cover in Vaseline
Always warn patient of risk of these teeth coming out
Can drill a hole in the impression tray if very mobile and hold tooth with thumb as removing tray

Question 16

What is a reline?

Answer 16

Adding new base material to the tissue surface of an existing denture in quantity sufficient to fill the space which exists between the original denture and the altered tissue contour

Question 17

What are indications for a reline?

Answer 17

Poor adaption
Extensions are incorrect

Question 18

What is a rebase?

Answer 18

Replacement of the entire denture base

Question 19

What are the different types of relines?

Answer 19

Temporary (conditioner)
Soft - for parafuncitonal habits/ obturator (CLP/ Cancer)/ very atrophic ridges
Permanent - hard acrylic, useful if problems with peripheral seal, can prolong lifespan of old dentures

Question 20

What are the differences between lab and chairside relines?

Answer 20

More residual monomer left in chairside (irritant)
Need a wash impression for a lab reline

Question 21

What are the different types of materials used for soft relines?

Answer 21

Heat cured acrylic
Self cure acrylic
Heat cured silicone
Self cure silicone

Question 22

What factor can cause a soft reline to go hard over time?

Answer 22

Excessive load on residual ridge

Question 23

What are the disadvantages of chairside soft reline?

Answer 23

Plasticiser leaches and deteriorates over time, becomes porous and harbours microorganisms

Question 24

What are the components of heat cured acrylic?

Answer 24

Powder:
PMMA particles, Initiator benzoyl peroxide, Plasticiser, pigments

Liquid:
Methacrylate monomer (dissolves PMMA), inhibitor, co-polymers

Question 25

What are the components of self cure PMMA?

Answer 25

Similar composition to heat cured but tertiary amine in the liquid activates benzoyl peroxide
Therefore, little thermal contraction (better fit?)

Question 26

Where is primary and secondary support on an upper denture?

Answer 26

Hard palate = primary
Alveolar ridge = secondary

Question 27

Where is primary and secondary support on a lower denture?

Answer 27

Primary = buccal shelf and pear shaped pad
Secondary = alveolar ridge and genial tubercles

Question 28

Where are the areas of relief on a lower denture?

Answer 28

Lingual ridge and mylohyoid ridge

Question 29

What materials can be used to modify a stock tray prior to taking the impression? And their properties?

Answer 29

Putty (silicone base and catalyst system- expensive, fast setting)
Soft red wax (cheap, can manipulate easily, poor dimensional stability)
Red composition (cheap, requires boiling water, short working time)
Green stick (cheap, requires heating, hard to manipulate, better for small additions to special trays)

Question 30

What are special trays made of?

Answer 30

Self cure PMMA

Question 31

What is the purpose of a spacer (special tray)?

Answer 31

Modelling wax used to create a spacer to allow space for material (while still close fitting)

Question 32

Give examples of spacers required for different types of impression material?

Answer 32

Alginate = 3mm
Silicone elastomers = 3mm

Question 33

What is the function of green stick mould stops?

Answer 33

The aid positioning of impression, maintains space for material, allows consistent placing of tray

Question 34

What are the aims of a master impression?

Answer 34

Well rounded borders
Minimal air blows and none in important areas
Impression centrally placed
All clinically relevant areas included

Question 35

What are the stages of an immediate denture?

Answer 35

Primary impression
Design
Master impression
Jaw reg

Mark on cast which teeth are to be replaced
Include date required for insertion

Lab cuts off tooth/ teeth and construct the denture

Question 36

What are the post op instructions for an immediate denture?

Answer 36

Dentures kept in for 24 hours after to ensue socket isn’t disturbed
Review appt asap
Remove denture and examine healing of socket
After 24hours, advise warm saline mouthwash

Review after 2 weeks as may require further adjustments/ fixative
Replace 6 months- 1 year later

Question 37

What are the advantages of a replica denture?

Answer 37

One less clinical stage
Jaw reg is simpler
Minor changes to design are possible

Question 38

What are the limitations of replica denture?

Answer 38

No major changes to design
Acceptance of some flaws in design
Not suitable if significant resorption since denture fabrication

Question 39

What are the clinical stages of replica denture?

Answer 39

Primary impression
Master impression and jaw reg
Try in
Delivery

Question 40

What is involved in the primary impression for replica dentures?

Answer 40

Clean denture
Modify with green stick if needed

Apply adhesive to stock trays (2 required per denture)
Need 5 scoops of lab putty per impression and add one width of activator per scoop of putty - mix until even consistency
Place into stock tray and push in denture
Ensure margins of denture are level with putty

Cut locator notches into putty (middle and one each side)
Apply Vaseline to the putty surrounding denture
Cover denture with another 5 scoops of putty
And sandwich with opposing tray and smooth putty around the edges

Wait until fully set to remove denture