Closed Sandwich technique: This technique is used when a glass
ionomer is placed in an area where there is no contact with the cavosurface
of the preparation. The material is completely covered with
the restorative material. (Base and liners) A liner should be used as a
very thin covering over deep and questionable dentin surfaces. A
base should be selected anytime the material is placed thicker than
.25 mm and should be a high strength restorative material. Tooth
conditioning is not required with this technique.
Open Sandwich technique: This technique is used when a Glass
ionomer is placed in an area where there is contact with the cavosurface
on the preparation. The margin of the preparation is sealed
with the Glass Ionomer material. A restorative material should
always be used here and the tooth conditioner is indicated.
Class II Open Sandwich: Used when any part of the gingival
margin of a Class II preparation has been extended past the CEJ and
no longer has an enamel cavo-surface.
1. After placement of the matrix, condition the gingival floor with GI
conditioner for 10 seconds and wash off.
2. Place either a pure glass ionomer or a resin modified glass
ionomer interprox. to the start of enamel margins. Do not build
interproximal or occlusal contact in this material. Make sure that
there is a minimum of 2mm of the final restorative material above the
Glass Ionomer to support the marginal ridge.
3. Continue with step 4 with the above composite technique if final
material is a composite restoration.
