Copy dentures and relines Flashcards
What is a soft lining
A soft cushioned lining inside the denture to stop pressure points and make eating more comfortable
What are the indications for a resilient lining material (soft lining)
- Patient experiences persistent pain under denture
- To reduce pain during function
- Previous positive experience of a soft lining
What might cause pain during function
- Sharp bony ridges
- Superficial mental nerve
- Thin atrophic mucosa
- Parafunctional habits
What material can we use for soft linings
- Silicone materials
2. Acrylic materials
Which is better silicone or acrylic for a soft lining
Both have their advantages and disadvantages but silicone is preferred
What do silicone materials for soft linings contain
- Poly dimethyl siloxane
- Silica filler
- Plasticizer
Give advantages of using a silicone material for soft linings
- Material is elastic so deforms under load
- Silicone is inert
- Feels soft to patient when 2mm thick
- Remains soft forever
Give disadvantages of using a silicone material for soft linings
- Need special burs when adjusting
- Prone to colonisation with candidia as its porous
- Requires an adhesive to glue to denture as its inert
What is acrylic material for soft lining made up
Powder and liquid
Give advantages of using a ACRYLIC material for soft linings
- Bonds well to denture base
2. Is soft due to plasticisers
Give disadvantages of using a ACRYLIC material for soft linings
- Plasticisers leach out in time leaving the material to harden
- Doesn’t feel as soft to the patient as silicone does
- Is visco-elastic meaning it takes time to soften
What is the minimum thickness needle for an acrylic vs silicone lining
Acrylic: 2-3mm
Silicone: 2mm
What is the what is the compliance (softness) of an acrylic vs silicone lining
Acrylic: softness decreases with time
Silicone: soft forever
What is the glass transition temperature of an acrylic vs silicone lining
Acrylic: 20-30 degrees when new
Silicone: -130 degrees
What is the bone to denture base like of an acrylic vs silicone lining
Acrylic: good binding
Silicone: requires a bonding agent
What is the surface finish like of an acrylic vs silicone lining
Acrylic: good
Silicone: poor
What do we mean by glass transition temperature
The temperature when a material becomes rigid and hard
How long do chariside soft reline materials last
3-6 months at most
How long do lab soft reline materials last
1-3 yrs
Other than patient comfort when else might we use soft liners
- Used in undercuts in tuberosity areas
2. Used as an obturator
When do we carry out a reline
If a denture becomes ill fitting due to the change in the shoe of the tissues over time
What is a reline
Making the denture fit again by relining it with material
What can we use to reline a denture
Can use hard setting or soft but we usually use acrylic
What are the problems associated with a chair side hard reline of an upper denture
- The hard lining can make the palate thicker
- Can increase OVD
- Exothermic polymerisation
- Monomers can be irritant / allergenic
- Destroy post dam which can reduce retention
- Chair line may not be fully cures as lab materials
What are the advantages of making a chair side hard reline
- Immediate result
2. Few states fro errors to creep in
What are the disadvantages of making a chair side hard reline
- Inferior physical and mechanical properties
- Monomer
- Reline material may lock into undercuts of a partial denture
How do we carry out a laboratory reline
- An impression is taken when denture is in situ
- Light bodies silicone wash placed inside the denture
- Impression sent lab where model is cast and heated cured acrylic reline carries out
What are the advantages of making a lab made hard reline
- Good physical and mechanical properties
2. Rebasing is possible
What are the disadvantages of making a lab made hard reline
- Patient needs to be without denture for a few days
2. Errors can creep in due to impression taking
What material can we use for a hard reline
Tokuso
What material can we use for a soft reline
Coe soft
How do we carry out a chair side hard reline
- Apply rebase aid
- Mix material
- Place over fitting surface
- Insert into mouth and ask the paint to bite together
What are the indications for a chair side hard reline
- Previous dentures are satisfactory but just ill fitting due to bone resorption
- New denture satisfactory occlusion and neutral zone but unstable or unretentive
What are tissue conditioners used for
They can odder instant improvement in fit of denture and relief of pain but they only last for a week
Describe the composition of tissue conditioner materials
- Powder acrylic beads
2. Liquid ethyl alcohol
what is ethyl alcohol
A plasticzer
Talk through the properties of temporary resilient lining materials
- Initial plastic flow
- Very soft but rapidly degrades
- Short term 1-2 weeks
When might we use a tissue conditioner
- To offer temporary relief from pain
- To help diagnose cause of pain
- to see if permanent soft lining would benefit
- Temporary improvement in fit of denture while new ones are being made
What is a copy denture
It is a duplicate or replica od a denture that attempts to reproduce the aspects of a patients denture that are good while improving certain aspects which we are dissatisfied with
Why do we make copy dentures
Faster than going through all the steps of making a denture
How do we make a copy denture
- Mould made of existing denture
- Wax acrylic replica constructed by lab
- Occlusion recorded
- Put on articulator and set up teeth for wax try in
- Try in
- Talk was impression and prices to fit
What are the advantages of copy dentures
- Shape of denture very similar to previous denture
- Time saving
- Fewer clinical stages
- Fewer impressions required
- Appearance can be maintained
What are the indications for a copy denture
- Older patients
- Patient who have worn their denture for many years
- Patent with problems in adapting to new dentures
What are the contraindication for a copy denture
- Previous denture is unsatisfactory
2. Previous denture has multiple defects
