Denture Base Materiasl

Question 1

denture physical

Answer 1

mimic or be capable of matching the natural oral tissues, dimensionally stable

Question 2

denture qualities

Answer 2

Mechanical- fracture strength, modulus of elasticity etc
Chemical- inert and not absorb fluids
Biological- none toxic and none irritant

Question 3

PolyMethylMethacrylate (heat cured)

Answer 3

Can show a shrinkage of up to 5/6% if mixed correctly usually at a rate of 2.5:1 powder to liquid ratio
Ease of use, although is user dependant
Can come in rapid (30 minute boil or traditional cure)
Come in a variety of shades to mimic a variety of human skin tones but also clear which can be used for orthodontic appliances
Can be stained by the technician to increase aesthetics further
Easy to perform additions and reline

Answer 4

Standard processing of a denture can achieve acceptable results. Ensuring the polymeric material is mixed correctly ensures the best results dry mixes result in a larger shrinkage and can result in a granular formation on the denture base surface dry material also may not flow thoroughly into the denture mould

Answer 5

Ensuring enough material packed in the flask reduces the risk of contraction porosity. In a study comparing injection-moulding packing techniques showed a cross arch shrinkage of 0.65% in comparison to conventional PMMA which showed a shrinkage of 0.9%. Clinical studies show shrinkage of 0.5% didn’t affect the fit of the denture whereas the shrinkage of 0.9% showed the denture didn’t fit. There was a noticeably better fit of the injection moulded dentures on the palatal border.

Answer 6

It has also been shown that the most distortion of PMMA and injection moulded dentures occurs on removal of the cast. Looking at another study that compared the clamping techniques showed there were more dimensional changes in the processed denture using Traditional Flask Closure techniques (TFC) as opposed to flask closers that use screws to anchor the flask halves

Question 7

Resilient liners/tissue conditioners

Answer 7

Used for patients that cannot tolerate a hard denture base, usually where a patient has an atrophic ridge or uneven or thin/friable mucosa
Requires to be permanently soft though they do harden over time
Requires 2mm of hard acrylic and 2mm of resilient liner to be effective
Requires good adherence to a denture base
Can incorporate into a patients current denture base

Question 8

PEEK

Answer 8

Generally provided in a pressed disk processed by milling, however can be in the form of granules to be pressed by injection moulding
Presents with favourable properties such as excellent biocompatibility, is even more lightweight, can be considered as more aesthetic as no metal visible.
As it has a higher elasticity it reduces torque stresses on abutment dentition compared to chrome.
Suggested for those with poor periodontal conditions but can place a high stress on the mucosa.