Indirect and Direct Restorative Protocols - Caulk

› PRINCIPLES & PRACTICES
Direct Resin Restorations:
Considerations for
Adhesive Bonding
› Abstract:
It is the obligation of the
practitioner to provide the
dental patient with the most
aesthetic restoration using
clinical techniques that
ensure proper function,
biocompatibility, and
preservation of sound tooth
structures. Composite resin
materials and adhesive bonding
techniques are well suited for
such concepts of conservative
dentistry. Consequently, a
thorough understanding of
adhesive bonding procedures
and knowledge of adhesive
material options are
prerequisites in contemporary
dental practice.
During tooth preparation for
a direct resin restoration,
residual organic and inorganic
components form a
“smear layer” of debris on
the tooth surface. This barrier decreases the
permeability of dentin and must be removed
or made permeable so that resin monomers
or adhesives can contact and interact with
the dentin surface. Two fundamental strategies
are used to overcome the smear layer:
■ Total-etch: Adhesive systems with an
acid gel to condition dentin and enamel
surfaces, dissolving the smear layer
and 1 µm to 6 µm of hydroxyapatite.
■ Self-etch: Adhesives that treat the
dentin and enamel surfaces with a
non-rinsed solution of acidic monomers
in water. These bonding systems
make the smear layer permeable to
subsequently applied monomers.
Etch-and-rinse adhesives used in the totaletch
technique involve separate etching and
rinsing steps, followed by the application of
a hydrophilic primer and/or bonding resin
to produce a “hybrid layer” or resin-dentin
interdiffusion zone. With an etch-and-rinse
adhesive, the prepared tooth surface must
remain slightly moist after the etching gel is
rinsed away. Overdried dentin must be rewet
in order to raise the collapsed collagen to
a level suitable for bonding.
One-bottle, etch-and-rinse adhesives
such as Prime & Bond® NT (DENTSPLY
Caulk, Milford, DE) combine the primer
and adhesive resin into a single step that
achieves micromechanical interlocking of
monomers with the collagen-rich etched
dentin. The nanofiller technology of this
material reinforces the hybrid and adhesion
layer, protecting against microleakage and
postoperative sensitivity while establishing
a proper marginal seal. Its combination of
nanofillers and PENTA chemistry results
in a material that eliminates postoperative
sensitivity and ensures patient comfort.
The chemistry of XP BOND Adhesive
(DENTSPLY Caulk, Milford, DE), a universal
self-priming adhesive, provides an
extended working time and has a wider wetto-dry
preparation tolerance than previous
etch-and-rinse adhesives. Its ability to penetrate
into the conditioned collagen network
ensures the formation of an optimal bond.
Figure 1. Preoperative view of defective fi lling that requires replacement
with a direct composite resin restoration.
Figure 2. Conservative cavity preparation is facilitated by adhesive-based
approach that preserves sound tooth structures.
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