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CERECDOCTORS.COM
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QUARTER 4
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2014
since gb black’s era, dentistry has
evolved from his tenets
of “exten-
sion for prevention” to a more conserva-
tive approach.
1
This has been enhanced
by the introduction of, and advances in,
adhesive materials and their placement
techniques. Though adhesive proto-
cols involving preparations primarily
in enamel are well documented with
demonstrated clinical benefits, bonding
to dentin remains challenging.
2
Adhe-
sives and bonding to acid-etched enamel
enable dentists to strengthen teeth while
simultaneously ensuring patients of long-
lasting restorations,
3,4
including those that
do not require extensive tooth prepara-
tion. Dentin bond strengths, however,
tend to deteriorate over time,
5
and poor
bond quality can significantly reduce the
fracture load-bearing capacity of ceramic
materials.
6
Pre-curing bonding agents and dual-
curing luting resins have been shown
to optimize the dentin bond despite
thick ceramic layers.
7
However, bond
strength has been shown to be nega-
tively impacted by:
• Bonding to enamel without prior
phosphoric acid etching
• Lack of separate light-curing of a
light-polymerizable adhesive prior to
cementation
• Use of a light-polymerizing adhesive
converted into a dual-polymerizing
adhesive, and
• Use of a dual-cure luting
agent with a low auto-
polymerizable potential
8
On the other hand,
Maximizing Potential for
Minimally Invasive Restorations
Maximizing the Benefits of Conservative Adhesive Dentistry
Using Digitally Designed and Milled Partial-coverage Restorations
C A S E S T U D Y
| | |
B Y J A S O N H O RW I T Z , D . D . S .
and improving the quality, flexibility
and accuracy of the restorations. Digital
dental technology, such as utilizing
digital impressions and in-office and
laboratory CAD/CAM, makes delivering
accurate and durable inlay/onlay partial
coverage restorations a much more effi-
cient endeavor.
PARTIAL VS. FULL-COVERAGE
RESTORATIONS
Many full-coverage restorations are
placed because clinicians may feel they
are a more acceptable and predictable
alternative to large, direct composite
restorations, which may be prone to
polymerization shrinkage and the detri-
mental consequences that follow.
11
Yet, full-coverage crowns require
extensive preparations that do not
preserve patients’ natural tooth struc-
ture.
11
One study examined the guide-
lines for complete restoration coverage.
It was determined that teeth gener-
ally should be prepared to exhibit
10 degrees to 20 degrees of total occlusal
convergence, a minimal occlusocervical
dimension of 4 mm for molars and
3 mm for other teeth and an occluso-
cervical-to-faciolingual dimension ratio
of 0.4 or greater.
14
Overall, by some
accounts, approximately 63 percent to
73 percent of the coronal tooth structure
is removed when a tooth is prepared for
an all-ceramic crown.
15
As an alternative to traditional full-
coverage restorations, indirect partial
coverage restorations represent a
more conservative option for restoring
properly performed adhesive protocol,
proper material selection and their use
all facilitate conservative treatments in
cases where otherwise more aggressive
restorations may have been used. This is
especially true of partial coverage resto-
rations (i.e, indirect inlays and onlays),
where today’s stronger, more durable
ceramic materials can be utilized for
more minimally invasive treatments.
9
While other restorative options remain,
their inherent challenges — such as
difficulty establishing proper interprox-
imal contacts, potential for incomplete
polymerization, and time and labor
intensiveness
10
— have influenced clini-
cians to restore teeth using more heavily
prepared full-coverage procedures,
which are hardly conservative and not
always esthetic.
11
Additionally, these options have
sometimes been less resistant to masti-
cation forces, often necessitating more
frequent replacement and, therefore,
more tooth preparation that results in
inflammation to the nerve of the tooth
that has been shown to increase the risk
of pulpal involvement.
Adhesive bondingmaximizes strength
and predictability, enabling clinicians
to perform procedures that preserve
natural tooth structure and benefit from
the characteristics of today’s all-ceramic
materials.
12,13
Moreover, today’s all-ceramic mate-
rials enable partial coverage restorations
to be milled either in a laboratory or
chairside using computer aided design
(CAD), streamlining the overall process
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