Orthotown December 2021 - 39

Fig. 2: A do-it-yourself magnetic stirrer unit. The lid was 3D-printed with the SprintRay Pro printer and was designed to fi t the build plate.
The main drawback of laser-beam SLA
printers such as Form 3s is their relatively
slow printing speed compared with alternatives
on the market, such as DLP and
LCD printers. Printing speed might not be
a critical factor if the practice production
volume (number of parts printed per week)
is low. The extremely user-friendly dental
3D-printing solution offered through the
Form 3 desktop printer drew dental providers
to this 3D printer at the expense of reduced
printing speed.
Direct light processing: Direct light
processing-also known as digital light
processing-printers share similar parts as
laser-beam SLA printers, except the layerby-layer
projection protocol of UV light on
the membrane. Specifi cally, the projected
UV-light layer on the tank polymerizes
the resin layer by layer according to the
data encoded by a slicer program. Next,
the build plate moves vertically upward,
pauses, and repositions downward close to
the membrane, determined by the print
layer thickness (50-200 microns).
The print time of DLP printers is
independent of the number of parts on a
build plate per print run, because all the data
in a layer project at once. Instead, the print
time is dictated by the height of the object
and the per-layer build plate oscillation
time. DLP printers share common parts
like the DMD unit because of a limited
supply of these parts; nonetheless, DLP
printer manufacturers customize other
parts of a printer.
The manufacturers of DLP printers use
the following factors to reduce the print
time or improve the quality of details in
parts printed by these printers:
* Continuous DLP (build plate
optimization) printing.
* Force feedback sensors.
* Resin tank design.
* DMD resolution.
* Dual projectors.
In sum, current attributes associated
with DLP printers favorably position these
printers for an IOA. It has been speculated
that volumetric 3D printing might change
this dynamic in the future.
LCD masked SLA: Masked-LCD or
LCD printers use a liquid crystal display
to block the UV light projected on a resin
tank. LCD printers have been majorly
improved in the past fi ve years. The initial
improvements for LCD printers were in
the homogeneity and intensity of the UV
light. The next round of improvements
were on the resolution and structure of
the display: 4K, 5K and 8K LCDs have
been slowly integrated into 3D printers
Catch up online:
Determining
the right printer
for your practice
In Part 1 of this series,
Dr. Rooz Khosravi discussed
the benefi ts of implementing
an in-offi ce aligner protocol,
the types of digital software
packages available,
and more essentials. If
you missed it, head to
orthotown.com/magazine
and fi nd it in the lineup of
our November 2021 issue.
with the promise to improve the details of
3D-printed parts.
It is important to note that higher-resolution
displays bring a new slew of challenges
in these printers, such as reduction of light
intensity passing through a high-resolution
display. Monochrome displays were another
introduced solution to improve the UV
light quality polymerizing the resin. The
conventional RGB (red/green/blue) was
replaced with a monochrome display made
of black and white pixels aiming to achieve a
consistent high-quality UV light and ideally
to increase the lifespan of the display.
The inexpensive entry point to 3D
printing is the appealing factor to use
masked-LCD printers for an IOA system.
orthotown.com \\ DECEMBER 2021 39

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Orthotown December 2021

Table of Contents for the Digital Edition of Orthotown December 2021