What is sandwich?
• Something resembling a sandwich;
especially composite structural material
consisting of layers often of high-strength
facings bonded to a low strength central core.
• A restoration in a tooth in which two
restorative materials are used that are
chemically bound together.
• Here, a glass-ionomer or flowable composite
material is used as a liner under some
• Closed sandwich technique: The underlying
material does not come into contact with the
• Open sandwich technique: Usually used for
Class II restorations where the underlying
material forms part of the axial wall and is
exposed to the oral environment.
Glass Ionomer Cement
• Benefits as a liner:
–Bonds both to the tooth structure and the
composite, increasing retention form and
providing better seal when used at non-
–Fluoride in the GI material reduces
potential for recurrent caries.
• Benefit as a liner:
–Acts as a shock absorber, distributing
stresses applied to the more rigid
–May reduce some of the negative effects of
Indications of Sandwich Technique
• Lesions where one or more margins are in
dentin-like cervical lesions (class V)
• Class II composite restorations
• When any part of the gingival margin of class
II preparation has been extended past the CEJ,
and no longer has an enamel cavo-surface
2. Condition the dentin and enamel surfaces
using an acid conditioner (preconditioning)
• Function of conditioner:
–Creates stronger bond between tooth and
–Removes smear layer and debris from tooth
• Citric acid and polyacrylic acid have been
used as conditioners.
3. Place an increment of GIC over the cavity
floor, extending up DEJ around the perimeter
of the preparation, or just short of the cavo-
margin at the base of proximal box (In Class II)