Page 22 - CEREC Q4 | 2014

20 | CERECDOCTORS.COM | QUARTER 4 | 2014
| | | P U R I
There are no situations where I would “never”
use ceramics since the clinical performance of HPP
and ceramics is very similar. I would tend to use my
common sense and use ceramics in the presence
of an existing ceramic occlusal coverage on the antag-
onistic tooth, for best matching wear. In the anterior
dentition, there is no doubt that porcelain is the ideal
material for indirect bonded veneer restorations
(Iwouldnever used indirect composite resin veneers).
DO YOU FEEL THERE ARE ADVANTAGES TO A RESIN
BLOCK THAT ISMILLED TO FABRICATE AN INLAY
VERSUS A DIRECT COMPOSITE RESTORATION FOR A
MOD PREPARATION?WHAT ARE THE DISADVANTAGES
OFMILLING VERSUS PLACING COMPOSITE DIRECTLY?
Well, it is interesting that you ask that, aswe designed
a study specifically to investigate that question.3 Para-
digm MZ100 inlays not only increased the acceler-
ated fatigue resistance (100 percent survival in our
test) but also decreased the shrinkage-induced crack
propensity of remaining cusps when compared to
direct restorations. I have to admit that while both
restorative techniques yielded excellent fatigue
results at physiological masticatory loads, CAD/CAM
inlays seemmore indicated for high-load patients.
WITH THE RISE IN POPULARITY OF FULL-CONTOUR
ZIRCONIA, DO YOU THINK THAT STRONGER IS BETTER?
OR AREWE AT A POINTWHERE THEMATERIALS ARE
“STRONG ENOUGH”?
I believe that strength of a material must be in inverse
relation with the bond strength to the substrate. In
other words, the stronger the material, the less we
need to relyonbonding and themorewe relyon reten-
tion and resistance form (full-coverage restorations).
That should answer your question. People who don’t
know how to bond or don’t want to bond need such
strong full-coverage restorations to compensate.
The future is adhesive dentistry in the biomi-
metic approach because it is more conservative,
as opposed to resistance form and retention that
required much more cutting of intact tooth struc-
ture.4 Enamel is weaker than most ceramics, yet is
lasts for a lifetime because it is perfectly united with
dentin through the dentinoenamel junction.
In addition, we know very well that the
practitioner himself represents the most important
variable during any dental treatment. I cannot help
thinking that an average practitioner will likely expe-
rience fewer problems with biomimetic approaches
compared to more invasive techniques.
For patients with severely worn teeth, it has been
shown that the complications that arise fromconven-
tional prosthetic treatments aremuchmore dramatic
(often requiring root treatment or extraction) when
compared to the complications of themore conserva-
tive treatments with direct composite resins.5 These
are indeed easily repairablewith fewer consequences
to the remaining tooth structure and teeth. This is
explained by the principle of maximum tooth struc-
ture conservation. When it comes to cutting tooth
structure, the motto “less is more” always applies!
YOU ARE A BIG ADVOCATE AND PROPONENT OF IDS,
IMMEDIATE DENTIN SEALING. WHY SHOULD A CEREC
DENTIST PRACTICE IDSWHEN THEYWILL BE PLACING
THE FINAL RESTORATION THE SAME DAY?
Yes, of course because there are many advantages to
IDS related to the dentin adhesive process such as
bonding and sealing the freshly cut and clean dentin
(uncontaminated), the wet dentin bonding (enamel
can be bonded 100 percent dry separately during
luting) and the ability to pre-polymerize a thick
layer of adhesive resin without interfering with the
seating of the restoration, which is paramount for the
quality of bonding. Also, consider using composite
resin in addition to IDS to improve the preparation
design and surface (reinforce undercuts, smoothen
internal contours, etc.). Using the IDS process and
a CAD/CAM system, we have been able to generate
restorations without a single adhesive failure even at
very high loads, whether MOD inlays, thin occlusal
veneers6 or even thick overlays.7
IF YOU HAD TO CREATE AN IDEAL BONDING SYSTEM,
WHATWOULD THE BE CHARACTERISTICS OF THAT
BONDING SYSTEM?
My reference for bonding is the dentinoenamel
junction or, I should say, dentinoenamel complex
(more functional interphase including the inner
aprismatic enamel and mantle dentin) — the “adhe-
sive” characteristics of which are closely matched