Complete Dentures: Copy Dentures And Reline/rebase

Question 1

What can you do instead of making new conventional dentures

Answer 1

Make adjustments to old dentures such as by, soft linings, reclines, rebases and copies

Question 2

What are dentures made up of?

Answer 2

PMMA Poly(methyl methacrylate) which is a hard rigid material

Question 3

What are soft linings?

Answer 3

Soft linings are soft cushioned longings inside of the fitting surface of the denture to stop pressure points and make eating more comfortable.

Question 4

What are the indications for soft linings?

Answer 4

Clinical indications such as
*Pts who find dentures uncomfortable (tried getting used to them) but no anatomical concerns.
* Reduction of pain during function
-> Sharp bony ridges (after teeth have been extracted, instead of becoming rounded over they have retained sharp ridge
-> Superficial mental nerve (below lower premolars)
-> Thin atrophic (decreasing in size) mucosa
-> Para functional habits such as bruxism and attrition
* Previous positive experience of resilient linings

Question 5

What are the two types of materials you can use for soft lining?

Answer 5

Silicone and Acrylic

Question 6

What are the Advantages and Disadvantages of Silicone materials?

Answer 6

Advantages
Feel softer to the patient when 2mm thick
Considered an elastic material so instantly deforms under load
Remains soft forever
Disadvantages
Need special burs when adjusting
Silicone is inert ( Lacking the ability or strength to move or chemically bond) so needs an adhesive to glue it to the denture
It is porous so prone to colonisation with candida causing denture stomatitis

Question 7

How long will silicone materials last before they need replacing?

Answer 7

2,3 years due to the adhesive wearing off and candida colonisation

Question 8

What are the properties of Acrylic

Answer 8

Minimum thickness of 2-3mm
The softness decreases with time
The temperature at which it hardens is at 20-30degrees
The bond to denture is good as material is similar to that of the denture
The surface finish is good
Durability is a short term proposition

Question 9

What are the properties of Silicone ?

Answer 9

Minimum thickness of 2mm
The softness remains permanently
The temperature at which it hardens is at -130degrees
The bond to denture requires bonding agent
The surface finish is poor
Durability is a short term proposition

Question 10

What other uses are Softlinings used for?

Answer 10

->Other uses include in other areas for example where their is undercut and a normal acrylic can’t get into e.g tuberosity regions.
->Obturator fore patients who have had a palate removed and denture bones into the walls of sinus for retention

Question 11

What is a reline?

Answer 11

If a Denture stops fitting as well as it used to, due to the change in the shape of the tissue beneath it over time. They can be refined to make them fit again. They fill the space between the gap which has formed.

Question 12

What materials are used for relines and where can they be done?

Answer 12

Two types
1. Soft setting (chair side) usually acrylic
2. Hard setting
They can be done either chair side or impression can be taken and sent to lab to be done in labs

Question 13

What are the issues with a chair side reline?

Answer 13

If a upper denture is relined it will make the palate thicker because it has a lining on top of it .
Pt will feel it to be more prominent with tongue
Exothermic polymerisation as using polybutylene methacrylate, this can be uncomfortable for some patients
Monomers can be irritant/allergic
Destroys the post-dam therefore may reduce retention
MAy not fully cure chairside compare to lab as in lab they will tend to cure at higher temperatures which can cause it to last longer in llab

Question 14

How are relines done in lab?

Answer 14

1. Start by adding light-bodied silicone Wash inside the denture (layer on top??)
2. Impression taken with denture in situ (in place) (Closed Mouth Technique) Whilst material is setting and we also need to do border moulding
   3.Sent to lab where they will pour up a model cast and heat cured acrylic reline carried out reline denture.

Question 15

What’s an advantage of Laboratory Rebase over a Reline?

Answer 15

It helps avoid excessive thickening of the palate and prevents increase in OVD

Question 16

How is a Lab rebase made?

Answer 16

Whole of fitting surface is removed and replaced with a whole new fitting material (usually PMMA, strong and well cured(can only be done in lab)
Can include a post dam
No increase in OVD

Question 17

What are the advantages and disadvantages of Relining/rebasing chair side?

Answer 17

Advantages
Immediately done chairside
Fewer stages for errors to creep in
Disadvantages
Properties will be inferior
More monomers so not longer lasting
For partial dentures reline material may lock into undercuts in between standing teeth and make the denture more difficult to remove

Question 18

What are the advantages of relining/rebasing in the LAB?

Answer 18

Advantages
Good physical and mechanical strength (properties)
Rebasing is now possible in the lab
Disadvantages
PAtient will be without the denture for sometime whilst its in the lab or being sent to the lab
Errors may creep in due to impression being taken and model pouring. FLASKING?
If heat is used to polymerise the lining, the existing base material may warp (breakdown or twist)

Question 19

What are relines and rebases usually done?

Answer 19

Done chair side for short term improvements, usually done when a new denture is on way anyway. Or waiting to get an appointment for dentist and waiting for that

Question 20

Which materials are used for relines in clinic

Answer 20

Tokuso for hard. Coe soft for soft reline - both powder and liquid which is mixed together to form a liquid to fill in the denture.

Question 21

How are chair side hard relines done? AND what are the indications?

Answer 21

1. Apply rebase Aid (breaks down any double bonds their are already in the existing denture making bonding more likely)
2. Mix the material
3. Place material over fitting surface, Insert into the mouth and ask patient to bite together. (Closed mouth technique)
   4.Carry out muscle trimming
   Indications
   Mainly for lower denture -ill fitting due to bone resorption
   -> New dentures when secondary denture wasn’t too good and occlusion is satisfactory
   Wouldnt do this if teeth are not in the neutral zone unstable or unretentive (LAb reline would be more appropriate)

Question 22

What’s are Tissue conditioners used for? And how are they done?

Answer 22

Quick procedure, can offer instant improvement for about a week in fit and pain relief.
It’s done by
* Similar to soft lining materials , described as a bandage, really soft cushioning material (patient with ulcers or stitches removed can helps make comfortable for them.
How are they made
1. In clinic called Visco gel (powder and liquid)
Starts off really soft, but overtime gets harder and starts to peel off

Question 23

What is the purpose and benefit of tissue conditioners?

Answer 23

To offer temporary pain relief
To help diagnose cause of pain
To help patient decide if they want a soft lining. This is reversible so if the patient doesn’t like it don’t have to out a soft lining on which tends to be irreversible for some time.
Temp improvement in fit of denture while new ones are being made. (Only takes a few minutes to do)

Question 24

What’s the process of making Copy dentures?

Answer 24

1. Start off by making a mould of existing dentures (silicon putty)
2. Lab turn this into acrylic/wax replica of original denture
   * acrylic base but the teeth are wax
   3.Occlusion recorded using blue mousse
3. In the lab they will replace each wax tooth with acrylic same size and shape
4. Comes back to us and we try them in and if successful take a wash impression and process to fit (this gets processed to acrylic

Question 25

What’s are the advantages of Copy dentures?

Answer 25

Advantages
1. Patient gets new denture which feels like there own
2.Time saving, minor adjustments no need for primary and secondary
3. Appearance can be maintained

Question 26

What are the indications for copy dentures?

Answer 26

Pt who has worn the same dentures for many years
Older patients
Pt with problems adapting to new dentures when they have an older set which was satisfactory

Question 27

What are the contraindications of Copy Dentures

Answer 27

Previous dentures unsatisfactory
- Teeth not in neutral zone
- Multiple defects

Question 28

What are the options for a patient who’s dentures were never satisfactory?

Answer 28

Conventional remake, or if they have a previous set older set which were successful and can be found then we can use the **Copy technique **

Question 29

If a patient presents with successful dentures which they have had for many years which are now loose and showing wear what would you do?

Answer 29

Copy dentures OR conventional dentures

Question 30

If a patient presents with denture which have recently become loose but otherwise the pt is happy what would you do?

Answer 30

Rebase OR reline OR copy dentures OR conventional dentures