Class IV Restoration Flashcards
What causes class IV restorations?
Traumatic fracture of coronal enamel/dentin
Large Class III restorations
Replacement of discoloured/failed restorations
Aesthetic masking of intrinsic staining
Alteration of labial morphology
Toothwear
What are the difficulties faced with class IV cases?
Inability to achieve moisture control
Limited opportunities are available for retention (May need extra slots, pins are not recommended with composite anymore)
Problems with tooth position (Creating traumatic occlusion)
Difficulties achieving the final contour of the restoration (Restoring contact points if needed, labial, palatal and proximal contours)
Difficulties achieving the correct shade, translucency/opacity and texture
What does leakage of class IV restorations lead to?
Discolouration and caries
What are the clinical steps for class 4 restorations?
- Investigate site (Heavy occlusion requires increased retention and resistance forms, caries/fracture/restoration should be extended)
- Shade selection
- Isolate working field
- Pumice tooth
- Tooth preparation
- Restoration placement
- Finishing and polishing
How is site investigated for class IV lesions?
When trauma is involved:
The sensibility of the pulp needs to be assessed (pulp test teeth adjacent as well as the symptomatic tooth)
Check for mobility
Color chnage in that tooth compared to surrounding teeth
Integrity of the root needs to be determined by PA radiograph.
Integrity of adjacent soft tissues (Investigate surrounding tissue even under the lip)
What is the treatment done when class IV cavity extends into the enamel only?
Bonded composite restoration. Fractured corner is restored by bonding the fractured portion of the tooth back into place where possible.
What is the treatment done when class IV cavity extends into the enamel and dentin?
May require a liner to cover the dentin or base + liner depending upon the depth of the fracture into dentin.
How is retention and resistance provided for a class IV restoration of a cavity that extends into the enamel and the dentin?
Retention:
Bevel on labial side (ingual in some occasions)
Retentive groove on dentin at the proximal end of the fracture.
Resistance:
Ensure no unsupported enamel on margins
What is the treatment done when class IV cavity extends into the enamel, dentin and pulp?
May need endodontic treatment
What tests are required following trauma to an anterior tooth following class IV cavity?
The sensibility tests
Mobility assessment
Colour change + Follow up radiographs
Tests need to be carried out at 6 months, 12 months, and annually for a number of years because degenerative changes can occur belatedly
How is working field isolated?
Rubber dam
When can the slit/slot method be used?
Under normal circumstances the traditional rubber dam application style is the best.
The slit/slot method is acceptable when something precludes the use of the traditional approach.
How is a class IV cavity prepared?
Remove existing lesion or defective restoration using a round bur. If fractured little or no preparation required.
For all situations the teeth should be bevelled at the cavosurface margins. (always bevel in enamel)
When should we not bevel?
Very thin enamel
Margins close to the DEJ
Margins on cement
Margins in occlusal contact zones
How should large class IV lesions be prepared interproximally?
Boxlike shape with flat gingival floor
No unsupported enamel at the margin
Extend 0.5mm into the dentin
