What are the different factors/clinical steps for steps of crown try-in and cementation?
- Checking the models and the die
- The patient
- Equipment required
- Try in stage - check the crown fits
- Try in stage - checking the occlusion
- Cementation
- Review
What should you look for when checking the models and the die?
o Is the lab work crown (onlay or bridge) what you have prescribed on the lab prescription form.
o Does everything look right:
Correct material, shade – need to match different thickness of dentine, enamel, different staining, and different lustre of teeth for an acceptable shade match.
Has there been any damage to the models
Is the final occlusion correct.
What patient factors are important in clinical steps of crown cementation and try-in?
o Has the tooth been symptom free.
o Has the temporary remained intact and comfortable. If not over eruption and other problems may occur.
o Is local anaesthetic required – if tooth is vital use LA as there can be pain and discomfort from cementing and rubber dam on tooth.
o Remove the temporary as carefully as possible, excavator under margin and lift – cement hasn’t bonded anything, just locked in the temporary crown.
o Check the occlusion – could have over-eruption of the gaps don’t match the model.
o Ensure all temporary cement is removed clean the preparation with pumice/water.
o Protect the airway with gauze – assume you need a rubber dam until you don’t/can’t use it. Do split dam technique.
What equipment is required for crown try-in and cementation?
o Dental floss.
o Fit checker spray.
o Gold thickness gauge.
o Occlusal indicator paper.
o Straight hand piece dependent upon bur required.
What is needed for the try-in stage for checking the crown fits?
o Check the margins with a probe – shouldn’t feel a gap between margin and crown, but will feel the difference in material. If can’t find a defect, them the crown fits well.
o Check contact points with floss.
o Now, the occlusion can be checked using thin occlusal indicator paper.
What is important for the try-in stage for checking the occlusion?
o Spot adjustments to the occlusion.
o Adjust before the cement put on to avoid putting a hole in the crown or not being able to adjust it enough for the patient inside the mouth
What are the steps for cementation of a crown?
o Isolate and dry the preparation.
o Clean and dry the restoration – not dessicating the tooth if it is vital. Want to protet the dentine pulp complex so don’t make it too dry.
o Mix cement.
o Place a layer in the restoration – paint fitting surface of the crown with cement with a think film, not filling it to the brim as you don’t want too much excess.
o Seat restoration firmly, apply pressure.
o Ask the patient to occlude to check the casting is fully seated.
o Patient then occludes on a cotton wool roll while cement sets.
o Remove excess cement thoroughly – use microbrushes.
o Floss through contacts.
What advice do you give patient after cementation?
o Tell patient might be slight difference in the occlusion.
o Might be uncomfortable for patient for a week.
o Recommended eat on the other side while they get used to the crown so that the PDL doesn’t get traumatised.
What is luting cements?
- The interface between cast restoration and the tooth.
- Squeeze out excess from the side where we can get to it and wipe off the excess.
- Crown should fit the same as when there wasn’t cement in it. Should not be an obvious cement line.
Which cement should you use?
- Choice depends on how much adhesion is needed.
- Whether aesthetics of the cement is important.
- Whether you may want to remove the restoration.
What are the properties of cements? (4)
- Prevents microleakage
- Good mechanical properties
- Biocompatible
- Ease of use
What is the importance of preventing microleakage?
o Protects pulp.
o Maintains aesthetics
o Prevents sensitivity
o Prevents secondary caries.
What is included in good mechanical properties?
o High compressive strength.
o Low solubility
o Retentive to tooth and restoration.
o Low film thickness.
o Needs to be fluid not viscose or else you’d have to force the crown onto the tooth.
What does a biocompatible cement mean?
o Not harmful to pulp
o Not harmful to gingivae.
o Don’t want excess cement in the gingival margins as can lead to gingivitis.
What is “ease of use” for a cement?
o Sufficient working time
o Easy to clean up excess.
o Crown can be removed if necessary.
What are the different types of cements?
- Traditional cements:
o Zinc phosphate – can also be used for temporary crown as can be cleaned off easily.
o Zinc polycarboxylate - Glass ionomer cements:
o Traditional
o Resin modified - Resin cements:
o Multi-step adhesives
o Simplified and all in one adhesive.
What are the indications for using zinc phosphate?
- Traditional cement
- Full crowns
- Conventional bridges
- Cast posts
What are the properties of zinc phosphate?
o Long record of clinical success
o High compressive strength
o Low film thickness
o 5 minutes working time
o Introduce powder in small increments when mixing to achieve longer working time.
o No adhesive properties – macro-mechanical retention. If tooth has rough surface and so does the crown, the cement can set hard into the roughness of the surfaces providing mechanical retention, so don’t need adhesive properties.
o High solubility.
What are the indications of zinc polycarboxylate?
- Traditional cements
o Full crowns
o Conventional bridges
o Inlays/onlays
o Temporary filling material.
What are the properties of zinc polycarboxylate?
o Moderate compressive strength.
o Acceptably low film thickness.
o Chemical adhesion to tooth.
o Moderate solubility.
o Add powder quickly to the liquid when mixing.
What are the indications of RMGIC (Fuji Plus) as cements?
o Full crowns
o Conventional bridges
o Inlays/onlays – not as retentive so need adhesive cements to stick them on.
What are the properties of RMGIC cements?
o Require dentine conditioner (Citric acid) for optimal results.
o High compressive strength.
o Acceptably low film thickness.
o Chemical adhesion to tooth and all base metals.
o Fluoride release.
o Low solubility.
What are the indications for Resin Adhesive - multi-step (Panavia F)?
o Full crowns
o Conventional bridges
o Inlays/onlays
o Resin retained bridges – tooth not prepared
o Veneers
o Posts
o Bonded amalgam.
What are the properties of Resin Adhesive - multi-step (Panavia F)?
o Dual Cure resin composite system.
o Very high bond strength to tooth and metal alloys.
o High compressive strength
o Acceptably low film thickness.
o Fluoride release
o Low solubility
o Multiple components
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Revision of endodontic principles27
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Success/failure in endodontic treatment12
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Restoring endodontically treated teeth26
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Extra coronal restorations - crowns and laboratory stages17
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Principles of tooth preparation16
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Shade selection in dentistry26
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Impression techniques and soft tissue management27
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Extra-coronal restorations - treatment planning17
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Temporary crowns18
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Elastomeric impression materials37
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Crown fitting and cementation36
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Periapical pathology33
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Medical devices (MDR) regulations23
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Jaw movements and articulators36
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The TMJ32
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An introduction to partial dentures 131
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Materials for cementation31
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Partial dentures 2 - clinical and laboratory stages34
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Partial dentures 3 - partial denture design34
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Partial dentures 4 - impressions and recording the occlusion35
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Partial dentures 5 - anterior saddles and aesthetics20
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Fixed bridges25
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Partial dentures 6 - managing free-end saddles, try in and fit22
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Partial dentures 7 - Denture polymers27
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An introduction to oral surgery30
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Fascial spaces and the spread of infection30
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Clinical occlusal investigations12
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Occlusal factors in restoration failures9
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Complications of extractions in oral surgery32
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Abnormal bleeds21
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Inlays/onlays31
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Materials for crown and bridgework25
