Class II amalgam Flashcards
What is an embrasure?
V-shaped valleys between teeth that acts as a spillway for food to escape during chewing aiding the self-cleansing process
What is the marginal ridge?
The meisial and distal edges of the tooth
What needs to be considered about the restoration?
- Method of retention for material of choice
- Prevention of recurrent caries – elimination of microleakage
- Assist remineralisation of tooth tissue
- Longevity under occlusal load – fracture and wear resistance
- Protect tooth from mechanical failure
aesthetics
What is a class II restoration?
lesions occurring between posterior teeth only interproximally.
What is the isthmus?
Narrow part between the two cusps (two proximal flares)
What is a line angle?
the junction of two surfaces of the crown of a tooth, or of a tooth cavity
When would you not extend the cavity?
If the proximal lesion is visible and access is good then the marginal ridge can be conserved
If the tooth is caries free occlusally it is NOT necessary to cut out the fissure.
Class II prep start to finish?
- initial cut made through marginal ridge to penetrate the caries and then widened bucco-lingually - diamond pear shaped or tungsten carbide bur
- The proximal plate can be fractured off with a hand instrument (marginal trimmer) to avoid damage to the adjacent tooth (or you can use a matrix band)
- removal of caries with excavator especially ADJ
What is the size of the cavity determined by primarily?
Size of the carious lesion
How can some adhesion be achieved with amalgam?
Use of lutting/bonding agents
What should the cavo surface angle be at?
90 degrees to surface
What is the depth of the cavity for amalgam?
2mm (1-1.5mm elsewhere)
What do fractured margins need to be planed with?
Gingival margin trimmer in order to remove fragile enamel prisms which could break off and affect marginal seal
How would you achieve a rounded gingival floor?
Pear shaped bur assists with shape
Where are retention grooves placed?
placed 0.5mm deep to ADJ (dentine) gingivally fading away occlusally, rounded cross section. Directed laterally not pulpally
What do matrix bands and wedges do?
Separate teeth interproximally to help with carving margins and creating contact points.
Substitutes for missing walls
Restricts extrusion of the amalgam and formation of overhands or ledges
Provides contour for proximal surface restoration
How is the matrix band contoured?
Convex side of spoon excavator is used to impart a convex contour
How would you condense the amalgam?
- Use amalgam pluggers/condensers
- adaptation of the amalgam to the walls of prep
- Eliminate voids
- Incremental placement of 1mm thickness
What would you use to carve?
Wards carver e.g. No 2 or excavator
