Complete dentures - security and liners

Question 1

Denture security

Answer 1

Patient’s main concern
A function of Retention & Stability
Need to consider three surfaces:
Occlusal
Polished
Fitting

Question 2

Denture retention

Answer 2

Ability to resist those forces attempting to displace the denture at right angles to the supporting tissues
Effectiveness of fitting surface and peripheral seal

Question 3

Denture stability

Answer 3

Ability to resist those forces attempting to displace it in directions, other than at right angles to the
supporting tissues
Size and shape of the residual alveolar ridge

Question 4

Types of liners (linings)

Answer 4

Permanent
Semi-permanent
Temporary

Question 5

Permanent liners

Answer 5

*adding more plastic to denture*
Heat cured PMMA
-under pressure, in laboratory
-greater strength, less porosity, greater durability
-more expensive, takes longer
-hard material
Autopolymerising PMMA
-chairside
-quicker, but not very good
-element of porosity, less polymerised (exothermic reaction)
-compromised strength and durability
-hard material
Soft liners

Question 6

Hard permanent liners - indications

Answer 6

Relining dentures
Additions to dentures
Placement of post dams

Question 7

Soft permanent liners - indications

Answer 7

Relining dentures
Tender mandibular ridge
Over mental foramen
Needs to be at least 4mm thick

Question 8

Permanent liners - composition

Answer 8

Heat cured silicone – cured in the laboratory

Autopolymerising silicone – cured at chairside

Question 9

Permanent liners - indications

Answer 9

Friable but well-lubricated mucosa
Habituated patient
Obturators

Question 10

Temporary liners - classification

Answer 10

Soft liners
Functional impression materials
Tissue conditioners

Question 11

Temporary liners - composition

Answer 11

Usually PEMA, dibutyl phthalate, ethyl alcohol, benzyl salicylate
(types vary in proportions)

Question 12

Temporary liners - indications

Answer 12

Immediate dentures
Relief of pain
Conditioning of tissues
Functional impression material

Question 13

Retention may be broken by

Answer 13

Remaining tooth or particular muscle attachment

• overextended into buccal sulcus
• ** (first few mins of encore)

Question 14

PMMA

Answer 14

Polymethylmethacrylate

Dentures are made of PMMA

Question 15

Heat cured zinc oxide impression

Answer 15

Trim 3mm round periphery and trim any undercuts
Closed mouth technique with opposing denture in (dictates height of denture)
Make sure patient is biting at right height - check freeway space is the same

Question 16

Problem with silicone impression material

Answer 16

Hydrophobic

Question 17

Heat cured silicone impression

Answer 17

Used heavy bodied
-more accuracy but less resolution
Processed onto denture in laboratory
Bonding critical
Bonds best to fresh acrylic
Lasts 6/12-3 years

Question 18

Which impressions are more difficult - upper or lower

Answer 18

Uppers

Perforations needed to minimise thickness of material and any resulting increase in face height

Question 19

Autopolymerising (laboratory cure)

Answer 19

After a while, autopolymerising liners distinguishable from rest of denture because with time they stain due to slight porosity
Some contain a plasticiser and remain relatively soft for a period of months (Coe ‘super soft)

Question 20

Autopolymerising (chairside cure)

Answer 20

Plasticised, autopolymerising, PMMA and PEMA)
Dispensed as powder/ liquid, good handling properties, quick set
Linings, additions, post-dams

Question 21

Automix, autopolymerising

Answer 21

Softer than laboratory cured
More compatible with mucosa
Used for cleft lip and palate patients and oncology patient
-usually cleft lip and palate are surgically closed at birth