Class II. – modifications for
amalgam
 Conventional preparation
 Slot
 Large cavities – replacement of the
cusp (cusps), combination with the
cavity on vestibular/oral surface
Occlusal cavity Proximal cavity
MOD
Cavosurface angle
Slight reveres curve
Clearence of the proximal surface
Retention – grooves
in the proximal cavity
Divergency of axial walls
towards gingiva and
Convergency - divergency
towards proximal space.
Autoretention
Slot is a cavity that is open
on occlusal surface.
It is limited on the proximal ridge
Slot preparation
Slot for amalgam
 Access to the caries lesion
- through the enamel wall
- breaking out of the enamel lamella
- excavation of carious dentin
lroubal@med.muni.cz 12
Pre op
lroubal@med.muni.cz 13
Access to the cavity
Slot for amalgam
Autoretention
- Grooves
- Divergency towards gingiva
- Convergency and divergency of axial
walls in horizontal plane(towards
proximal space)
Slot for amalgam
 Rule of the gingival wall
-1 mm wide
-90% angle towards the pulpal wall
-outer line beveled if in enamel
-horizontal groove
Sedelmayer
Sedelmayer J. Amalgám – zapomenuté řemeslo.
Brno, 2000.
Bažant V.
Konservační zubní lékařství, SPN Praha,1962.
Slot cavity
 Limited on proximal ridge
 Axial walls are divergent towards gingiva
 The proximal box has a typical picture of
fish tail
 There are grooves:
- One horizontal in gingival wall
- Two vertical in axial walls
Large defects
 In vital teeth if the cusp has been
undermined due to dental caries
 Large defects in non vital teeth –
amalgam overlays
 Combination with the cavity on
vestibular/oral surface
Cusp has been removed
The thickness of the filling
3 – 4 mm (at the cusp)
Retention
Grooves, pins, slots
Parapulpal pins
Intrapulpal posts (root canal posts)
Retention in the endodontic
cavity
Large amalgam restoration -
overlays

lroubal@med.muni.cz 25
Amalgam
Exact work!
lroubal@med.muni.cz 26
Basic modifications
Rules for large restorations
 Clear and sharp outlines – cavosurface
margin
Thickness of the amalgam (the cusp 3 – 4 mm)
 Autoretention
- Grooves
- Pins, slots
- Parapulpal pins
- Intrapulpal posts – root canal posts
Resistance – acc to general rules
Preparation for adhesive
materials – composites
 No extension for prevention (adhesion)
 No grooves
 No undercuts
 Rounded box
 Bevel the axial walls and the outer edge
od the gingival wall
 Small isolated cavities are possible
Cavity for amalgam
Cavity for composite
Bevel on the gingival wall
Preparation
do not bevel!!!
Ohlazení zevní hrany
gingiválního schůdku mimo
sklovinu
Bevel of enamel on axial walls
Yes
No
Amalgam
Composite material
47
48
Sedelmayer
Alternative preparation – adhesive slot
Glassionomer and class II.
 Temporary filling – first phase for the
sandwich technique
 Tunnelová filling (preparation)
Tunnel preparation
1. Low caries risk
2. Proximal ridge without infrac
3. Good cooperation
4. Small caries lesion
1. Loups or microscope
2. Miniinstruments
3. Dezinffection
4. GIC in capsules
5. BW post op