Dental Asia March/April 2019

In Depth With
The blue light used by Primescan has less
penetration, and therefore better surface capture.
But in recent years, the word A.I. has
become this overused marketing buzzword
that conflates different categories of the
technology into one general term. To
make things more confusing, “A.I.” can
technically refer to any kind of software
that mimics intelligence and decision
making. The old CEREC 4.6 also had “A.I.”,
and look how that turned out.
For this reason, it is very exciting to see
the new CEREC 5.0 A.I., because it is
capable of self-learning. So the more
time you spend working with it, the better
its automatic margins and restoration
designs will be. The even better news is
that the learning processes is aggregated
and centralised at a main server controlled
by Dentsply-Sirona, then distributed to
all the end-users. This means that as a
new Primescan or Omnicam owner, you
can immediately take advantage of the
most mature and smartest version of the
software, trained by dentists all around
the world.
Is Primescan faster?
Yes. Primescan does feel noticeably faster
than the Omnicam, but keep in mind that
the Omnicam is currently already one of
the fastest scanners available. So how fast
do you need, really?
Is Primescan easier to use?
Despite the changes, veteran Omnicam
users will have no trouble adjusting
to the Primescan on the first try. The
new scanner’s large imaging area and
increased depth of field (up to 20 mm)
seems to keep the image capture more
continuous without breaks and the
addition of the touchpad and touchscreen
improves user experience. Do note,
however, that the Primescan is bulkier and
heavier than the Omnicam.
Is Primescan more accurate?
Accuracy can be divided into two
components: trueness and precision.
Trueness is how closely the data conforms
to reality (or the best approximation of
reality), while precision is how closely
the data conforms to each other. These
two concepts are mutually exclusive,
and therefore can be tested separately.
According to Dentsply-Sirona’s own
tests, the Primescan is able to achieve
the following accuracy:
Local Accuracy Global Accuracy
Trueness: 14 μm Trueness: 32 μm
Precision: 10 μm Precision: 30 μm
A trueness value of 14 μm (microns)
means that whatever you scan will be, on
average, within 14 microns of the target
object. While this is an excellent result, it
is not unheard of. In fact, similar numbers
have been achieved in other studies by
CEREC Omnicam, 3Shape Trios, and a
whole host of other scanners as shown
below:
For global accuracy, the numbers are
a bit more interesting. You can think
of local accuracy as how good a single
restoration fits. Global accuracy, then, is
how well a full-mouth appliance (i.e. clear
aligners, bite plates, implant frameworks)
fits. So an accuracy value as close to
zero (perfect representation of reality)
is desired.
First, a global trueness of 32 microns is very
respectable. For context, a study in 2017
compared four intraoral scanners and
found that their global trueness ranged
from 45.8 to 61.4 microns (see table 1).
Now you can definitely find studies that
shows even better results for a lot of
scanners, like this, this, this, this and this
study. Keep in mind, however, that there
are a few ways to do global accuracy
calculations (but let’s not get into it for
now). For the purpose of this discussion,
we can get a sense of a scanner’s
performance based on relative values,
and the Primescan’s results are looking
pretty good.
But numbers and figures can be
misleading, especially those with business
and financial implications. So we decided
to test it for ourselves.
Local accuracy values for desktop and intraoral scanners. Source: Heike, 2016.