Dentaltown November 2019 - 61

After years of study and development, Glidewell
Dental thought leaders determined that CT scanning
could have as momentous an impact on dentistry as it
has on the evolution of aerospace and medical imaging.
Armed with this knowledge and optimism, Glidewell
Dental has developed a new laboratory workflow that
leverages the micro-CT scanning of dental impressions
to fabricate BruxZir solid zirconia restorations. The
benefit to clinicians is clear: more accurate and consistent
restorations returned to the dental practice in fewer days.

The landscape before CT scanning
Before now, dentists ordering restorations sent impressions to the dental lab of their choice, which were digitized
so a CAD/CAM fabrication process could be initiated.
Such digitization is most commonly started with
the creation of a model made of a gypsum-and this is
where error is most frequently introduced into the process.
Gypsum models are subject to material changes based
on a litany of variables, ranging from temperature and
humidity to the ratio of gypsum powder to water and
the presence of air bubbles.1
Beyond this, human intervention in the trimming
process can introduce additional error, and there is
widespread potential for breakage given the relative fragility
of stone models. These are precisely the potential pitfalls
and frustrating inaccuracies that sent Glidewell Dental
engineers in search of a more precise restoration workflow.

The current landscape
When doctor-submitted dental impressions are scanned
directly using a micro-CT scanner, the potential impact
of these environmental variables is avoided because the
"model" created is an intangible digital file that reveals
the internal and external structures of the impression.
After digitization by the CT scanner, the remaining
workflow is virtually 100% digital; the captured file flows
from virtual model preparation to a restoration design
station, then to milling.

Speed is another factor that benefits greatly from CT
scanning, be it in digitization of impressions or in delivery
turnaround times of finished restorations. Conventionally,
dental laboratories employ a process that involved mixing
gypsum powder with water, pouring it into an impression
mold, waiting for it to settle and dry, then die-trimming it.
On average, this process takes 30-40 minutes, and
given the frequency with which it's repeated throughout a
given day, cases must sometimes wait until a production
team member becomes available. Compare that lengthy and
cumbersome process with CT scanning, where single-unit
impressions can be digitized in less than 30 seconds. (Longspan impressions take about 90 seconds.)

The accuracy for which
doctors have long waited
Speed is certainly an important factor, but the ultimate
benefi ciaries of CT scanning will be the patients in
whose mouths these CT-initiated restorations are seated.
Restorations made through CT-initiated workf lows
exhibit excellent margins, fit, contacts, contours and
occlusion-an example of Glidewell Dental's focus
on precision. For dentists, the excellent news is rather
obvious: Satisfied patients are loyal patients.
French writer Victor Hugo once wrote, "Nothing is
more powerful than an idea whose time has come." Hugo
was clearly not referring to restorative dentistry, but the
point is no less relevant: The time has come to elevate
the standard and expectation of what can be achieved
with restorations. The implementation of CT-initiated
impressions and their manufacturing out of BruxZir
solid zirconia heralds the arrival of a better, stronger,
faster restoration process. ■

References
1.

Kerr M, Park N, Leeson D, Nikolskiy S. Dimensional accuracy of microcomputed
tomography-scanned half-arch impressions. J of Prosthetic Dentistry. 2019 May;
121(5):797-802.

Abbreviating digitization:
From about 30 minutes to 30 seconds
The list of the benefits of CT scanning for dentists
and their patients is lengthy-primary among them are
the extremely accurate dimensional measurements, sharp
3D imagery, and production accuracy vastly more precise
than that produced from optical scanning methods.

dentaltown.com \\ NOVEMBER 2019

http://www.dentaltown.com

Dentaltown November 2019

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