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on control enamel surfaces. The loss of
height on the enamel antagonists them-
selves was 54.5 µm when operating in
contact with enamel, and only 27.6 µm,
when in contact with the VITA ENAMIC
restoration surface. Accordingly, on the
one hand, the chewing-induced wear of
the hybrid ceramic was practically iden-
tical to that of natural tooth enamel and, on
the other hand, the hybrid ceramic clearly
protects the tooth enamel.
what are the possibilities and
limitations of vita enamic in terms
of indications and design?
The degree of elasticity of the hybrid
ceramic and its reduced brittleness and
hardness broaden the range of proper-
ties of its silicate ceramic base, in that the
hybrid structure combines the characteris-
tics of the natural tooth substances enamel
and dentin. Because of that, Iwould expect
hybrid ceramic to be especially suitable
for the treatment of devitalized side-teeth
with partial and full crowns. In any case,
this is the indication we come across the
most in our student courses.
what can you tell us about
the processing and grinding
characteristics of vita enamic?
Theparticular suitabilityof hybridceramics
for shape-persistent and rapid machining
has already been mentioned. The easier
manual machining and polishing compared
to traditional ceramics makes hybrid
ceramics particularly easy to work with for
the dentist in clinical chairside situations.
where do you see vita enamichybrid
ceramic a fewyears fromnow?
In a few years' time, I envision that all
of the restorations made from VITA
ENAMIC hybrid ceramic will be in the
same condition as that in which they are
being placed in patients today. I antici-
pate that this material will prove itself
just as much in the treatment of devital-
ized teeth as it has in the treatment of
vital teeth in long-term studies.
what is the particular benefit of
this hybrid ceramic, based on it
being both resilient and elastic?
in otherwords, why should the
concept of the so-called strength
of a dental material be redefined?
In my view, the strength and stability of
single-tooth restorations such as inlays,
onlays, crowns and veneers can now be
geared toward the properties of the natural
tooth for stability, and less so to extremely
hard, heavy-duty frameworks. The defi-
nition might be "The strength of a dental
material for single restorations should,
together with the residual tooth, achieve
approximately the same resilience as the
natural tooth."Bear inmindthat theflexural
strength of natural enamel is low without
its sub-layer. Its strength is the result of its
evolved internal (“adhesive”) alliance with
the dentine. The development of CEREC
was possible only on the basis of the adhe-
sive technique, which allowed ceramic
CEREC1/VITABLOCSMark I restorations
to be lastingly and tightly cemented with
posterior composite. After the usual etching
with hydrofluoric acid, the new hybrid
ceramic exhibits a highly retentive etching
pattern, thus providing ideal conditions for
long-lasting adhesive bonding. The elastic
properties of the material greatly increase
the resilience of the combination with the
hard tooth structure, as the aforementioned
studies show. This iswhy fracture-free, high
long-term stability can be expected even in
clinical settings.
whatwere the specific objectives
of the in vitro vita enamic tests
you conducted at the university of
zurich? were there any esults that
surprised you aftermore than 25
years of cad/cam experience?
The aim was, first of all, to examine the
above-mentioned grinding properties of
the hybrid ceramic in comparison to
established silicate, lithium and zirco-
nium dioxide ceramics, as well as
composite and polymer materials. A
further area that was worthy of interest
was the surface quality that could be
achieved with respect to the abrasion of
the material in the contact area with the
antagonist, and the abrasiveness of the
material compared to the natural tooth
enamel of the antagonist. Other than that,
we also performed hardness measure-
ments on all materials. What surprised
me was the significantly lower hard-
ness of the hybrid ceramic compared to
established ceramics. VITA ENAMIC
abrades the enamel antagonist signifi-
cantly less than silicate and lithium disil-
icate, unambiguously making it the most
enamel-friendly ceramic material of all.
On machine polishing the surface of the
hybrid ceramic, the same gloss values can
be achieved as with the silicate ceramics;
after abrasive tooth brushing in a labora-
tory test, the gloss obtained with VITA
ENAMIC was of similar quality to that of
nanocomposite.
also, itwasn't just patients
whowere treatedwith vita
enamic during the clinical tests
conducted at the university of
zurich; you had an inlayfitted on
yourself. what feedback have you
had from patients so far, andwhat
are your experiences as a patient?
Patients who already had some experi-
ence with CEREC restorations reported
the lower hardness and the certain degree
of elasticity of the material to be pleasant.
This reflects my own experience as a
patient. Obviously, I assume that the resis-
tance of the VITA ENAMIC surface actu-
ally matches that of natural tooth enamel.
Myprevious clinical observations over four
to sixmonths, especially scanning electron
microscope findings in relation to wear
facets, reveal a wear pattern on the hybrid
ceramicwhich is very similar to thatwhich
is observed on tooth enamel. Our abrasion
measurements in the chewing simulator
confirm this with over 1.2 million chewing
cycles. The enamel cusps mounted into
the chewing simulator produced a 46.1 µm
loss of height on VITA ENAMIC contact
surfaces, and a similar 42.3 µm height loss
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