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adversely affect the successful delivery
of a CAD/CAM-generated restoration: a
contaminated restoration; residual contrast
medium; and a tooth either desiccated or
soaked in saliva.
The first step to bonding anything is
to ensure you have a clean surface. In
the case of a CAD/CAM restoration, this
requires two things: 1) Removal of all of
the milling oil/lubricant from the resto-
ration, and 2) Removal all of the imaging
powder from the tooth
surface. Steam has been
defined as the gold stan-
dard to remove the milling
Two Concepts Essential to Consistent CAD/CAMRestorations
Delivering a CEREC Restoration:
The Keys to Success
throughout the rapid growth of
CAD/CAM technologies, a lot of time and
effort have been spent developing ceramic
blocks, ceramic materials, stains, glazes,
imaging technologies and milling units.
Unfortunately, the actual mechanics of
delivering thefinal restorationhave lagged.
After spending a significant amount of
time designing, milling and preparing
the CAD/CAM restoration, many doctors
complain that patients suffer post-delivery
sensitivity or debonds. The following is a
description of a protocol that will result in
a highly successful restoration and a satis-
fied patient.
There are a number of things that can
C A S E S T U D Y
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B y J o h n K a n c a I I I , D . M . D . , a n d R i c h R o s e n b l at t, D . M . D .
lubricant, and should be used on all resto-
rations as soon as they exit the milling
unit. In the absence of a steam cleaner,
cleaning the restoration thoroughly with
alcohol may be substituted.
The imaging powder is a bit more
challenging, as it exists within the oral
environment and is inherently difficult
to remove. If the imaging powder is not
completely removed, the particles can
block interaction of the bonding system
with the surface, which could lead to
sensitivity or debonds. It is far more diffi-
cult to remove the powder than is gener-
ally understood. The Ti02 powder is
heavy and largely insoluble, so air-water
spray is not very effective. A strong acid
can remove the powder, but such a tech-
nique could compromise the perfor-
mance of many bonding systems.
CAD/CAM users have different opin-
ions as to the disposition of the prepared
tooth following scanning and during
the machining of the restoration. Some
keep the tooth isolated via a rubber dam
or Isolite. If isolation is maintained, the
tooth must be continuously remoistened
in order to prevent desiccation, which can
adversely affect bonding systems and lead
to post-operative sensitivity. If isolation
is not maintained during the machining
process and no temporary is placed, the
tooth may be immersed in saliva for the
duration of the milling process. Salivary
contamination has been shown to reduce
bond strengths and might also lead to
bacterial presence under the restoration.
The most reliable technique to assure
success is one of prevention: do not allow
the powder to contaminate the prepara-
tion; do not allow the tooth to desiccate;
1
2
Step 1: Prepare the tooth for the
restoration.
Step 2: Apply Surpass Self-Etch Adhesive.
and do not permit salivary contamination.
This is most easily and predictably done
by applying the bonding system prior to
powder application.
The following protocol is the ideal
way to prepare a tooth for imaging and
delivery of a CAD/CAM restoration:
•
Prepare the tooth for the CAD/CAM
restoration.
•
Apply Surpass (Apex Dental Materials,
Inc.) as permanufacturer’s instructions.
•
Wipe off the oxygen-inhibited layerwith
a cotton pellet soaked in either isopropyl
or ethyl alcohol, rinse and dry.
“
The most reliable
technique to assure
success [of a CAD/
CAM restoration]
is one of prevention.”
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