Relines and Rebases Flashcards
What is a reline?
Adding new base material to the tissue surface of an existing denture in a quantity sufficient to fill the space which exists between the original denture contour and the altered tissue contour (occurs due to bone resorption)
What is a rebase?
Replacing the entire denture base material of an existing denture
What are the types of relines?
Temporary
Soft
Permanent (technically nothing is permanent)
What are the uses of temporary relines?
Tissue conditioning- if grossly ill-fitting dentures or for reducing inflammation in denture bearing area
-> coecomfort/viscogel
In post immediate dentures
After implant surgery
-> may be better to encourage patient not to use denture at all to avoid pressure around surgical area
How is tissue conditioning carried out?
If dentures are very loose
Place onto fitting surface- will fill gap between surface and ridges
If happy with reline, this can be converted into PMMA (can be used as functional impression- if using visco-gel)
What are the issues with tissue conditioners?
Gets discoloured long term
Poor aesthetics- may overlap onto flange (can be trimmed with scalpel)
When are soft relines used?
Parafucntional habits
If ridges very atrophic
On obturators in cancer and cleft patients
-> good for sensitive naso-pharngeal tissues
What are the issues with soft relines?
Hardens over time- continuous reviews required
Plasticiser leaches out- deterioration
Porous- harbour microbes
What are the types of soft lining materials
Heat cured acrylics and silicones
Self cure acrylics and silicones
-> sometimes known as cold cure (misnomer as exothermic reaction)
How do self and heat cure acrylic soft linings differ?
- HEAT CURED ACRYLICS – powder is methacrylate based (such as polyethyl methacrylate) activated by benzoyl peroxide in liquid containing monomer and plasticiser
- SELF CURED ACRYLICS – as above but rather than heat it is a tertiary amine that acts upon the benzoyl peroxide
How do self and heat cure silicones differ?
- HEAT CURED SILICONES – processed against acrylic
-> Contain a siloxane material and a filler of silica - SELF CURED SILICONES – similar to impression materials for composition and setting
What is used for permanent denture relines?
Hard acrylic
-> often done in lab
What are the ADV of permanent relines?
Useful in peripheral seal problems
Correction of errors following inadequate
master impression
Immediate/post-immediate dentures
Prolongs lifespan of some older dentures- if teeth are not worn and in good condition
What are the steps in a reline?
Treat the denture like it is a special tray
Remove areas of flange that have undercuts (upper anterior maxilla)
Use light bodied/low viscosity impression material(not too much- careful not to increase OVD and decrease FWS) around periphery (shine through is more acceptable in this situation)
Butter over the edge to allow some flow over
Get patient to hold together- allows adaption of tissues (border mould- to get nice impression to give seal)
Denture goes to lab
Overcast is used to hold denture in position
Model of ridge is created, post dam added (will be obvious if historic denture wearer)
Fitting surface is removed
Denture placed on overcast with model on other side- gap between is filled with wax
Palate is filled with wax
Dundee injection moulding
When denture comes out flask- there will be a lot of flash etc (it may need Adjustment chairside if technician hasn’t trimmed it up the way you wanted it)
Fit as new denture- disinfect, insert, review
What should you warn patients about if they are considering a reline/rebase?
You don’t have the same opportunity to give them their old denture back if new one is not as good
-> Don’t sell it up as much
Warn patient that denture feels thicker
