Crown fitting and cementation Flashcards
When looking at your models what question should you be asking yourself?
- Is the restoration you received it what you asked for
- Does everything look right
- Has there been any damage to the models
What might you put on your models to help the technician?
Black check lines to help the technician get a better idea of the patients occlusion
When looking at the crown what questions should you be asking yourself?
- Do the margins of the crown correspond to finishing lines on the restoration
- is the restoration itself well finished
- Are the contours of the crown correct
- Is the shade of the crown right
- Can you see any obvious flaws
When meeting your patient for the crown fitting appointment what questions should you ask them?
- Has the tooth been symptom free
- Has the temporary crown remained intact and comfortable
- How sensitive is the tooth
What could have happened in the appointment between placing a temp crown on and the crown fitting appointment?
Over eruption may have occurred
Talk through the steps you’d take BEFORE placing your permanent crown on a tooth
- Remove the temporary as carefully as possible (use the excavator under the margin and lift)
- Check the occlusion
- Ensure all temporary cement is removed
- Clean the preparation with pumice and water
- Protect the airway with gauze
How should you remove the temporary restoration
Use an excavator under the margins and lift
What equipment do you need to fit a restoration
- Dental floss
- Fit checker spray
- Gold thickness gauge
- Occlusal indicator paper
- Straight hand piece
Talk through the steps of checking if your crown fits
- Check the margins with a probe
- Check contacts with floss
- Check occlusion using thin occlusal indicator paper
What can happen if the contact point between your restoration and the neighbouring tooth is too loose?
Food packing can occur
What can happen if the contact point between your restoration and the neighbouring tooth is too tight
will be uncomfortable
How do you check the occlusion of the crown
Use articulating paper to se if there is any high points
Use a high speed rugby shaped burr to remove an extra high points on the restoration
Talk through the stages of cementation
- Isolate and dry the preparation
- Clean and dry the restoration
- Mix cement
- Place a player of cement in the restoration
- Seat restoration firmly and apply pressure
- Check occlusion
- Remove excess cement thoroughly
- Floss through the contacts
After cementing the crown what should you do?
- Ask the patient to occlude normally to check the casting is fully seated
- Ask patient to occlude on a cotton wool roll while cement sets
After your crown fitting appointment when should you next see the patient
Review patient in 2 weeks time (or tell them to call if they experience any problems)
What does luting cement form
The interface between cast restoration and the tooth
When choosing a cement what do we need to take into consideration
- How much adhesion is needed
- Aesthetics
- Will you need to remove the restoration in the future?
List the ideal properties of a cement
- Prevents micro leakage
- Good mechanical properties
- Biocompatible
- Ease of use
Why does a cement need to be able to prevent micro leakage?
- To protect the pulp
- Maintain aesthetics
- Prevents sensitivity
- Prevent secondary caries
List some good mechanical properties a cement should have
- High compressive strength
- Low solubility
- Retentive to tooth and restoration
- Low firm thickness
Why is it important for cement to be biocompatible ?
- So it doesn’t harm the pulp
2. So it doesn’t harm the gingiva
What do we mean when we say the cement should be easy to use
- Should have a sufficient working time
- Easy to clean up excess
- Crown can be removed if necessary
Name the different categories cements can fall under
- Traditional cements
- Glass ionomer
- Resin cements
Give examples of traditional cements
- Zinc phosphate
2, Zinc polycarboxylate
Name some glass ionomer cements
- Traditional
2. Resin modified
Give examples of resin cements
- Multi step adhesives
2. Simplified and all in one adhesives
What are the benefits of using zinc phosphate to cement crowns?
- Has a long record of clinical success
- High compressive strength
- Acceptably low film thickness
- 5 minute working time
- No adhesive properties
What are the indications for using zinc phosphate as a cement
For
- Full crowns
- Conventional bridges
- Cast posts
What is the trade name for zinc poly carboxylate
Poly F
What are the benefits of using zinc poly carboxylate to cement crowns?
- Moderate compressive strength
- Acceptable low film thickness
- Chemical adhesion to tooth
- Fluoride release
What are the indications for using zinc poly carboxylate as a cement
For:
- Full crowns
- Conventional bridges
- Inlays/ onlays
- Temporary filling materials
What does RMGIC stand for?
Resin modified glass ionomer cement
What is the trade name for RMGIC
Fuji plus
List some of the benefits of using RMGIC as a cement
- High compressive strength
- Acceptably low film thickness
- Chemical adhesion to tooth and all base metals
- Fluoride release
- Low solubility
What does RMGIC need to give optimal results?
Require a dentine conditioner (citric acid) for optimal results
What are some of the indications for RMGIC
for:
- Full crowns
- Conventional bridges
- Inlays/onlays
What is a disadvantage of zinc phosphate?
Has a high solubility
What is the trade name for resin adhesive multi step cement?
Panavia F
What is a disadvantage of resin adhesive multi step cement?
Has multiple compounds and steps
List the steps for using resin adhesive multi step cement
- Acid etc
- Paste A
- Paste B
- Liquid A
- Liquid B
- Metal primer
- Ceramic primer
- Oxyguard
What are some of the benefits of using resin adhesive multi step cement
- Dual cure resin composite system
- Very high strength to tooth and metal alloy
- High compressive strength
- Acceptably low film thickness
- Fluoride release
- Low solubility
- Multiple components
What are some of the indications for using resin adhesive multi step cement
For:
- Full crowns
- Conventional bridges
- Inlays/ onlays
- Resin retained bridges
- Veneers
- Posts
- Bonded amalgam
What is the trade name for resin adhesive simplified?
Rely X ultimate
Name the 2 components that make up resin adhesive simplified
- Scotchbond universal
2. Rely x ultimate cement
What are some of the benefits of resin adhesive simplified
- Self adhesive dual cure resin composite
- Very high bond strength to tooth and metal allow
- High compressive strength
- Acceptably low film thickness
- Low solubility
- Built in metal and ceramic primer so less steps so less chance of error
List some of the indications for resin adhesive simplified cement usage
For
- Full crowns
- Conventional bridges
- Inlays/ onlays
- Resin retained bridges
- Veneers
- Posts
Looking at the criteria below which cement would you recommend for this crown prep:
- FVC/MCC crown prep
- Adequate retention
- Larger than 3mm
- An adequate taper
RMGIC (Fuji plus)
Looking at the criteria below which cement would you recommend for this crown prep:
- Unretentive prep
- Short crown
- Inlay/ onlay
Adhesive redin cement (panavia or rely X ultimate
Looking at the criteria below which cement would you recommend for this crown prep:
1. Resin retained bridge
Adhesive redin cement (panavia or rely X ultimate
Looking at the criteria below which cement would you recommend for this crown prep:
1. Fibre post
Adhesive redin cement (rely X ultimate
Looking at the criteria below which cement would you recommend for this crown prep:
- Cast metal post
- Needs to be easily removable for Endo later
Traditional cement (Zinc phosphate)
What are some of the problems that can arise during the fitting of a crown
- Crown feels to high to patient
What would you do if the crown feels high to the patient
Check margins to see if the crown is fully seated then use using shim stock
If the crown is fully seated but the patient feel like it is high what should you do?
- Check the occlusion with occlusal indicator wax or articulating paper
- Adjust the crown checking the thickness doesn’t become less than 3mm
- Polish crown before cementing
- Check the fitting of the crown again
- If it still doesn’t fit you will need to re make it
What is the minimum thickness your crown should be?
3mm
If the crown is NOT fully seated and the patient feel like it is high what should you do ?
- Check the fitting surface for obvious defects
- Check the prep for remaining temporary cement
- Make sure the prep doesn’t have an undercut
- Check the model isn’t damaged
Talk through the steps you’d after you have evaluated if the fitting surface has an defects
- IF there is any defects adjust and retry
- If there isn’t any defects check the contact points to see if they are too tight
- Use fit checking medium inside the crown
- If none of that works you will need to remake the crown
How do we check if the crown is too high?
Using shim stock
What is Shimstock?
8 microns thick metal foil that we can place between the teeth to see if there is a good contact
