Security and Liners Flashcards
What 3 surfaces must you consider?
Fitting, oclusal and polished
When is denture retention?
Ability to resist those forces attempting to displace the denture at right angles to the supporting tissues
What factors are involved in denture retention?
Effectiveness of fitting surface and peripheral seal
Adaptation of fitting surface to underlying ridge
Extension (buccal sulcus) - achieve good peripheral seal
What is denture stability?
Ability to resist those forces attempting to displace it in directions, other than right angles to the supporting tissues
What factors are involved in denture stability?
Size and shape of residual alveolar ridge
Occlusal loads
Tissue compressibility
Contacts - premature contacts can cause denture to tip
What are the 3 types of liners?
- Permanent
- Semi-permanent
- Temporary
What are permanent liners made from and where used?
Autopolymersing PMMA
Heat cured PMMA
Lab or chair side cure
Indication hard permanent liner?
Relining dentures
Addition to dentures
Placement of post dam
Indication for soft permanent liners?
Relining dentures
Tender mandibular ridge
Over mental foramen
How thick does soft liner need to be?
4mm at least
How to carry out softeners chair side?
Remove undercut (most seen anterior area) or extend any short area
Use zinc oxide eugenol for impression - closed mouth technique
Perforation needed to minimise thickness of any material - may result increase face height
Why is close mouth technique used?
Avoid increasing vertical dimension
Problems with auto-polymerising liners?
After a while become distinguishable from rest of denture - stain due porosity
Some contain plasticiser and remain relatively soft for period of months
How to use auto-polymerising liners chair side?
Dispensed as powder/liquid
Good handling properties and quick set
Used: liners, addition and post dam
How are heat-cured silicones used?
Cured in labs
Processed onto denture in lab
Bonding critical - best bond to fresh acrylic
