Continued from p. 79
As with traditional analog crown and bridge, there are rules, protocols, and quality standards.
The dentist and technician must be retrained on how to use the equipment. These machines
are not magic wands. All the technology cannot replace a skilled practitioner. There are those
who preach how dentists and labs will be replaced in a few years, but a lab scanner is the same
as a wax spatula to the technician, and the intraoral scanner is just another tool for the dentist.
If you look upon this technology as another necessary tool, you will realize how much it benefits
your practice in efficiency and predictability.
As we have seen with the computer industry, cell phones, and electric cars, demand creates
more options and better products. As the technology advances, we will be able to produce more
varied prosthetics and use more tools. Digital is not the final innovation in dentistry. There are
hydro scanning systems that perform like sonograms. New composites, polymers, pectin, lithium
disilicate hybrids, zirconia, and more are being researched and beta tested now. It is conceivable that we may use stem cell technology to print teeth. The possibilities
are endless, and it is the dentists who will be using this equipment. There
is no replacement for trained professionals.
STEVEN PIGLIACELLI, MDT, CDT, is the owner and vice president of Marotta
Dental Studio. He is a faculty instructor in postgraduate prosthodontics at the New York
University College of Dentistry. Steven is the founder and president of the Association of
Innovative Dentistry, an organization dedicated to supporting the next generation of
dentists, specialists, and technicians.
Continued from p. 44
HOW TO RELIABLY BOND ZIRCONIA
I began to realize, however, that the step I
wasn’t paying much attention to was one of
the most important ones: decontaminating
the intaglio of the restoration, which is the true
source of the zirconia debonding issue.
Bear with me as we discuss the chemistry
involved: The zirconia we use in dentistry is
zirconium oxide, and the oxide part is where
all the bonding happens. It is the functional
phosphate groups that bond to the zirconia.
But wait, what else contains tons of phosphate?
That’s right, saliva. Therefore, once a crown is
tried in the patient’s mouth, all of the potential
bonding sites on the zirconia crown are now
irreversibly occupied by phosphate groups.
Once this happens, we need to remove these
phosphate groups to make the oxide sites ready
to bond again.
This is easier said than done. Wiping with
alcohol doesn’t do anything. Sandblasting can
do it—however, most manufacturers recommend you leave the sandblasting to your laboratory. Some claim that excess microetching
with aluminum oxide can increase future
fracture risk. However, microetching is an
important step because it’s theorized to increase bond strength by increasing surface
energy of the intaglio surface.
5, 6 Porcelain etch
(hydrofluoric acid), although helpful for glass
restorations like lithium disilicate, doesn’t do
anything clinically relevant to zirconia. Oh,
and phosphoric acid etch? Big no-no. Phosphoric etch just makes the problem worse by
flooding whatever oxide groups aren’t already
occupied by phosphate with, you guessed it,
How do we remove the phosphate from the
oxide sites we need to bond to? There are two
reliable methods: Ivoclean (Ivoclar Vivadent)
and Sodium hypochlorite (NaOCl).
Ivoclean is superconcentrated zirconia oxide in a liquid suspension (so make sure to
shake well before using). It acts like a magnet
to remove all the phosphate from the crown
by creating a concentration gradient. Rinse off
after 20 seconds, and now you’ve got a zirconia
crown with all of its oxide groups ready to
accept a bond from your cement.
Another recently discovered method is to
just wipe the intaglio of the crown with gauze
that is soaked in 5% sodium hypochlorite. The
theory is that NaOCl breaks down the phosphate
groups so they can no longer bond, and it can
be removed by rinsing with water followed by
8 Bleach, then bond—voilà!
In conclusion, it’s possible to bond zirconia
as long as you ( 1) effectively decontaminate the
tooth and the crown and ( 2) bond following the
instructions of the cement manufacturer.
Author’s note: The author would like to
thank Mark Hartslief, BSc, RDT, and the New
York Center for Digital Restorative Solutions
(NYCDRS) laboratory and knowledge center
for fabricating the pictured restorations
and their contribution to this case study.
NYCDRS can be contacted at (646) 757-5840
firstname.lastname@example.org. Visit them at
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ALEC J. GANCI, DDS,
FICOI, attended Stony Brook
School of Dental Medicine,
completing an oral surgery
externship in Madagascar. He
continued his training as a
resident at North Shore
University Hospital, serving as
chief resident, and completed a
two-year fellowship in advanced prosthodontics and
implant dentistry. He is an industry consultant and
lectures extensively on various topics, including implants,
dental materials, digital dentistry workflows, and esthetics.
He can be reached at