Dental Asia January/February 2024

CLINICAL FEATURE
As root canal-treated teeth are more
susceptible to fractures, tooth 47 was restored
with a root post and an adhesive build-up during
preparation. To create a biologically wide zone
between the gingiva and the crown margin
and to prevent possible chronic gingivitis, the
gingiva was remodelled using an electrotome
(Fig. 3). Retraction cords were placed around
the prepared teeth to displace and retain the
gingiva from the tooth neck (Fig. 4).
During the subsequent intraoral scan of
the prepared situation, the upper jaw was
scanned first. Before scanning the lower jaw,
the previously placed retraction sutures were
removed. An astringent retraction paste was
applied for temporary additional retraction
and hemostasis of the marginal gingiva and
to drain the sulcus. After the scan of the
prepared mandible, the final step of the digital
impression was to take the bite. Up to this
point, the treatment lasted approximately
90mins.
The data set of the intraoral scan was
transferred to the dental lab without further
processing so that the fabrication of the
restoration could begin. The patient was
allowed to leave the treatment room for the
duration of the crown preparation. She was
asked not to eat anything during the waiting
time so as not to cause any irritation to the
prepared teeth.
WORK STEPS IN THE LAB
The crowns were digitally designed with
exocad software. The occlusal space
available posed a particular challenge. For
an anatomically and functionally correct fit
of the restoration, it was necessary to fall
below the minimum wall thickness of 1mm
recommended by the manufacturer.
The design of the two crowns and the creation
of the corresponding digital images took
approximately 20mins. After this, nesting took
place where the objects were virtually placed
on the build platform of the printer. A Varseo
XS DLP printer was used. Once the required
support structures had been correctly placed
and planned, the print job could be started.
Printing the two crowns took around 40mins.
The printed objects were cleaned of residual
resin in ethanol and polymerised in the
BEGO Otoflash post-curing unit. When using
VarseoSmile Crown plus, the printed objects
should be blasted at a pressure of 1.5bar
between the cleaning and post-curing steps to
remove the ceramic deposits on the surface
of the objects caused by cleaning in ethanol.
This process was also considered in the
fabrication of the two crowns. The blasting
agent used was Perlablast Micro.
Finally, the printed and polymerised crowns
were individualised with VITA Akzent LC
composite stains (Figs. 5 and 6). The finished
crowns were delivered to the dental practice
just 90mins after preparation.
INSERTION
Back in the treatment room, the crowns were
first tried in. While an exact fit had already
been achieved at the preparation margin, a
check of the bite revealed the need for manual
correction of the occlusal points. After
correction, the occlusion was checked with
Shimstock foil and found to be satisfactory.
Fig. 3
Fig. 4
Fig. 5: VITA Akzent LC was chosen as the composite stains
Fig. 6: A view of the completed crowns that took 90mins to produce
40 DENTAL ASIA JANUARY / FEBRUARY 2024