Tutorial 5 - metal framework try-in Flashcards
what may prevent a cobalt chrome denture framework from seating correctly?
Distortion of the framework
Cast broke in the hands of the technician, so they tried to glue it back together but did the framework wrong!!
Faulty bite registration
Poor impression taking
Recent soft tissue trauma, eg due to extraction, causing swelling
if a patient comes in complaining that the denture is too tight, why may this be?
new dentures often feel tight - need to understand if this is just the patient getting used to it or if it is an incorrect fit
too much pressure on the soft tissues - if there is not enough space between soft tissues and the acrylic, this can put pressure anf feel tight. can be fixed with acrylic bur in some cases
overextended flange - can be fixed with an acrylic bur
establish whether the patient has been storing the dentures correctly when removing them from the mouth - they lose water if not placed in water, which can contribute to shrinkage
recent trauma to the soft tissues, eg due to an extraction. this will need to be investigated to understand the cause and so that it can be treated accordingly
undercut is engaging too much, which makes it hard to remove or insert the denture
if the patient comes in complaining that a denture is too loose, why may this be?
if this has happened over time, this may be due to bone resorption. This is especially true if there has been an extraction made before fitting the denture
if the clasps arent engaging the undercut properly on the abutment tooth, which may cause it - this can be fixed/adjusted with adam’s pliers
falances are too short to cover the necessary areas of the mucosa to create an efficient SEAL
lack of saliva - this acts as a natural adhesive/seal for the denture - can encourage the pt to stimulate saliva prod by chewing sugar free gum, synthetic saliva/saliva substitutes
OCCLUSAL VERTICAL DIMENSION may have been changed by the denture teeth wearing down over time, which can cause the denture to have poor occlusal contact
if a patient comes in complaining of pain with the dentures, why could this be?
incorrect occlusion - this can be checked with articulating paper and occlude spray to see if there are any areas in which the denture is sticking out and causing pain when occlusing/mastication. This could be if the clasp is interfering, or early contacts with posterior teeth, or if a rest seat is too high
overextended flanges - this can be trimmed with with acrylic bur
spicules of acrylic - same as above
Wear on the abutment teeth - this can happen if the clasp is engaging the undercut too much which is causing wear when taking the denture out/putting it in. can be adjusted using adam’s pliers
there could be ulcers/wear/cuts or painful lesions which have been caused by the denture’s friction on the soft tissues. if there is no identifiable cause (eg no acrylic spicules/overextensions), then the patient can have a soft lining material added to help them with the pain to the denture. they can also use topical treatments/saltwater rinses
very rarely due to an allergy - this would have to be investigated
retained roots - extraction needed
candida due to incorrect denture hygeine - patient should be told how to take care of the denture, and if it is deemed cecessary, prescribe antibiotics
what can occlude spray do and be used for?
this is a green colored marking spray used in dental procedures to identify areas of contact, pressure, or occlusal interference.
It provides a thin, visible layer that helps detect high spots in restorations, prostheses, or natural teeth.
why may a completed acrylic denture not seat down
poor initial impression - inaccurate, ROLLED BORDER was not captured
bite registration RVD/OVD not captured effectively
Over-extended flange
Incorrect occlusion and teeth positioning
Soft tissue swelling, could be due to recent XLA.
Acrylic material shrinkage during the curing process
Acrylic too thick
What clues can you obtain by studying the models that you may have problems fitting your framework? 4
A framework made on a model/cast where the tooth has broken and been incorrectly glued back into position will not fit the patient
Scrape marks and scratches on the model
Air blows, blobs of stone or drags on the cast udner the framework
The framework doesnt fit the model!
WHY WOULD A METAL FRAMEWORK FIT ON THE CAST BUT NOT IN THE MOUTH?
- DISTORTION - For example, if the secondary impression that made the model/cast was taken out too soon and distorted causing drag marks around the teeth, this is a reason why it may not fit the real teeth.
- TOO MUCH SILICONE FIXATIVE - this may not set properly and may cause the impresion to distort upon removal
How can you tell whether the framework is seated down completely?
Occlusal rests and the fit of the connector are the easiest ways to check.
Are the rest seats engaging the rests?
Is the major connector flush with the underlying tissues?
If the framework does not seat down fully, how will you correct this?
Ouse occlude spray to see where the framework is engaging in more areas than others - this will help us identify any points of concerns
Carefully use adams pliers away from the patient and adjust the position of the clasp arms if required. Ask teacher for assistance with this.
Trim down any over-extended acrylic flanges
Trim down any acrylic spicules with acrylic bur
If a clasp is loose, what shall we do at the framework try in stage?
Rather than adjusting a lose clasp at the framework fit stage, we may wait until the final fit to create a sufficient depth of undercut with composite resin
If the framework fits down well what else do we need to check?
CHECK OCCLUSION - look carefully to see if ICP is being achieved. You may need to use mirrors if difficult to see.
What may prevent the teeth from coming together?
Rest
clasps
minor connectors
soft tissue inflammation
If the teeth don’t meet in ICP after the framework has been created, what shall we do?
Take the framework out of the model and re-check occlusion. See if there is anything getting in the way - this will likely be due to a clasp or rest seat or minor connector being in the way.
What instructions do you need to write on your laboratory prescription?
If the framework fit is acceptable, the next clinical stage will be definitive jaw registration.
The instructions will be “Please add wax occlusal rims to the framework”:
Designing the framework when there is a very deep overbite can be a challenge - why?
There isn’t enough space for a metal mesh to retain the teeth.
Therefore, we need to first of all do a tooth try-in alone, then prepare the teeth for metal posts and the framework is made to fit the teeth.
Where space is very limited in these cases we use metal backings
