Complete Dentures - Try in and Fit Stages Flashcards
At the try in stage, talk in detail about the method of doing this.
- Check the fitting surface for any rough areas or undercuts. Adjust with wax knife.
- Assess if teeth are over ridges and if compensating curves are present. Assess on articulator if they have interferences in lateral movements for balanced articulation and occlusion.
- Place in patient’s mouth. Assess upper denture (retention, stability, extension, nz) and lower denture (retention, stability, extension, neutral zone). Then place both in the mouth and assess occlusion (in retruded contact and seeing if there’s any interferences while holding denture in place), freeway space and appearance.
- Check position of teeth: lip support (90-1110 degrees naso-labial angle, checking if tissues are taut or if lip vermillion border is showing), incisal level, intrapupillary line, alar-tragal line.
- Check occlusion. So you check to see the RVD using a willis gauge. Then placing both sets in, you see if there’s enough freeway space. This is by taking OVD away from RVD, by asking teh patient, visual inspection, and by asking the patient to speak.
- Ask about appearance.
What do you include on the prescription?
- Any modifications that need to be done.
- If not, if denture marking needs to be carried out.
- Position of a post-dam marked on cast and if second post-dam needs to be made.
- If high impact denture base needs to be used.
What to remember for flanges when checking?
If over-extended can be displaced and traumatising to soft tissues so can use Mizzi paste then trim.
If under-extended, can be poor retention and can make an impression with light bodied silicone in that area.
Also make sure it’s of good width otherwise air and water and food can get in and displace denture and break border seal.
If there are minor issues with teeth position or interferences, what do you do?
Adjust.
There are more ideas on what to do to fix problems on word doc.
At fitting stage, what do you need to check for?
All the same things + post-dam not too deep.
Check for contraction porosity and in this case don’t give it to the patient. This is where if there’s not enough pressure or material in the flask during mixing, small bubbles in the acrylic are allowed to expand. You can distinguish this from gaseous porosity by the fact it’s inside the denture.
In terms of comfort, what do we check for?
Post dam not too deep.
Over extension.
Acrylic pearls - assess using cotton wool. There’s air bubbles in acrylic when you mix powder and liquid together. If it’s at the edge of the mould under high pressure acrylic may pour into that air bubble forming an acrylic pearl.
When assessing occlusion, what’s important to do?
Hold the lower denture in place!
Why don’t we use articulating paper much when assessing occlusion?
At wax try-in it can displace teeth from wax.
At clinical try-in, it is thick so can leave marks on teeth that didn’t touch. So if you did use it, you’d ensure that you only remove a bit in the area you can feel and the patient’s telling you there’s a problem.
In case of denture issues, what would you do?
For smaller ones, grind the teeth and repolish.
For larger issues, re-record the occlusion.
If upper passed all the tests, re-record for lower only. If upper has issues, then do it for both.
What advice do you give to a patient after giving dentures?
- People will notice.
- Oral hygiene. Take them out at night after the first two weeks to avoid denture stomatitis and fungal infections. Wash with soap and water using soft toothbrush and rinse well, and also soak in denture cleaner once a week to remove any fungi or bacteria.
- Don’t use hot water as this bleaches the acrylic.
- Will take getting used to. Chew soft foods slowly.
- Might salivate excessively that’s fine.
- If it’s sore, try to get used to it. If really bad wear old dentures but before review appointment put it in 2-3 hours before.
- Recall appt in a week and then yearly reviews.
What is acrylic made out of?
PMMA - rigid, fractures easily, but is translucent and can be polished to a nice translucency.
What is the reaction?
Free addition polymerisation reaction.
Benzoyl peroxide produces free radical which is initiated by heat. Breaks the double bond in benzoyl peroxide and also in the methyl methacrylate and the monomers join to form a chain.
Terminates when no more monomer or two chains join together.
What is the process of making a denture?
- Wax pattern.
- Flasking to make a mould.
- Boiling the wax off.
- Placing a separator between plaster and PMMA.
- Using pre-polymerised PMMA to reduce shrinkage alongside liquid PMMA, in the dough stage.
- Allowing to set under high pressure (to reduce air bubble expansion).
- Processing in a hot water bath for a few hours. It should gradually reach 100 degrees to prevent monomer boiling and forming bubbles.
- This will all be polymerised PMMA. There is still some shrinkage.
What are some processing errors that can occur?
- Unpolymerised PMMA: can lead to loss of dimensional stability, can be rubbery as acts like plactisiser, can be allergen.
- Porosities: granular (unmixed liquid and powder), gaseous (boiled monomer because temp wasn’t raised high enough) and contraction (air bubbles expanded, goes through the full thickness and gives a cloudy appearance. gives an etched appearance that allows for plaque and food to collect and is weak).
At recall appointments, when patients complain of discomfort, what could this be attributed to?
- Rubbing because of xerostomia
- Over-extension of denture
- Undercut in most bulbous part of the ridge
- Occlusal contact far from site of trauma - adjust this before adjusting fitting surface.
