All-in-One Procera Implant Bridge (PIB) versus ... - Nobel Biocare

All-in-One Procera Implant
Bridge (PIB) versus soldering and
the laser/phaser-welder
TJ Nicolas presents a for and against from the technician’s perspective
Figure 1: The Procera All-in-One Implant Bridge (PIB)
Once upon a time there was soldering.
It was good. It was not easy, but it
worked; and it worked well. It required
years of experience and attention to
technique, which certainly resulted in
some phenomenal fits, almost always
delivered by the experienced. Those
were the days when precision gold work
on all implants was achievable; when
you could hear, hour upon hour, the
melodious drone of technician after
technician, chanting, ‘the impression is
probably not accurate anyway!’
For those who are unsure, soldering
is the joining of metals with a
complementary metal that has a
slightly lower melting temperature, so it
flows into the connecting space, fusing
the metals together.The additives in the
solder affect its properties in the solder
and influence its corrosion resistance in
the oral environment.
The technique sensitivity lies in:
• The gap between the two metal parts
easily being too large
• Getting the gap in the correct place,
perpendicular to the solder contracting
forces
• The solder not flowing, as the metal
may have oxidised prematurely, or the
metal was too cold
• Contraction, as the solder distorts the
framework on cooling
• Investment models that can easily
distort.
In my experience, the most accurate
and strongest joins have resulted from
using solder. I therefore:
• Split my castings down the centre of
a pontic, giving a much larger joining
area than a welded one (not possible
when you weld)
• Cast my framework in separate
castings, so that the 0.2mm joining
space is parallel and perpendicular to
the forces of soldering contraction
• Apply my flux on my joins before
I transfer it to my metal reinforced
investment model, and only then do
I heat the investment model so that I
have no oxidation
• Let my metal melt the solder, rather
than the flame used.
The results are second to none;
when firing porcelain, the solder joint
is stable, as they are large connections
through the pontic. As the solder joint
is not exposed to the oral environment
(because it is covered in porcelain or
a composite) we have no corrosion
issues. Where does that leave the
strength of post-ceramic soldering? Oh
— too much to consider — too much
104 Private Dentistry October 2008

Materials and equipment
Figure 2: Three implant level fits at 20 times magnification of a 14-unit seven implant PIB
responsibility — just tell me what to do!
I can hear the crunch of pliers, the
bang of a hammer, all to deliver yet
another passive substructure. After all
this, Wirz et al concluded, ‘Soldered
joints are described as having a clear
reduction in corrosion resistance, not
to mention tissue irritation.’ (And so
will lead to fracture, due to elements
in solders that help to reduce the
temperature.) At the time, it was all we
had, and it still has its place in modern
dentistry today.
Technicians lived, and technicians
retired and died. There were those
who could solder in this way and
who thought it was good. There were
those who were not so good at it and
who looked for other ways, so that
they didn’t have to do it any more.
Treatment plans changed, as did
techniques; and so the seed was sown.
These were difficult times for those who
knew not how.
The birth of laser-welding
Then came the birth of ‘titanium’ in
everyday dentistry. Now, not only could
the inattentive and under-trained not
solder, but neither could the skilled!
The race was on to solve the titanium
soldering problem. In a flash, ‘laserwelding’
followed, healing all wounds.
An intense heat source heats just the
area that needs melting together to the
maximum depth of 1.5mm (an average
connecter on a bridge should be 3mm).
Technicians were happy again because:
• There were no more investment
models
• It was direct on the model
• There was no more flux
• It was quick.
Although it is always unrealistic to
expect perfection, I was surprised when
I read a recent article on laser/phaserwelding,
(Lightening in a Bottle by
Joachim Mosch, Andreas Hoffman and
Michael Hopp), in which they make
the assertion that, ‘This development
can actually be considered one of the
major breakthroughs (advancements) in
dental technology in the last 15 years.’
They go on to say:
• ‘Proper welded joints will lead to a
perfect passive fit’
• ‘Consequently, the surface condition
of the components to be welded (highly
polished or sandblasted) will influence
the effect of the laser energy. The
shinier the surface the less effective the
laser will be, as more of the light energy
hitting the object will be reflected away,
reducing the ‘melting’ effect’
• ‘Laser-welders typically need service
and maintenance once a year, and a
new laser lamp, every three years’
• ‘In a laser-welder, the argon gas needs
to be adjusted almost every time before
welding, and the position of the nozzle
is often in the technician’s way’
• ‘The energy needed to penetrate the
1.5mm would overheat the alloy’
• ‘Practically, distortion must also be
considered. To avoid distortion during
the welding process, place the spots
carefully’
• ‘The bent bar at the top prevents
distortion’.
I stopped reading at this point
because it seemed to me that the
overwhelming evidence pointed to
the fact that to produce a passive,
complicated implant integral structure
is but a dream. I personally saw a laserwelded
implant bridge, where one of
the fixtures was shy of the implant
replica by 0.5mm. For me, laser-welding
is not the answer. It can do things that
conventional soldering sometimes
cannot do, but it is still only as good as
the technician who is using it. There is
still a ‘melting pool’ contraction at the
site of melting the metals. Depending
on the user, and using conventional
soldering, this can be larger than a
precision-soldered join at 0.2mm.
After studying articles, and trying the
process myself, I find laser-welding has
more applications than conventional
soldering, but I do think that in
conventional work, when repairing
holes in castings, the time taken to
re-wax and add the new unit into the
Private Dentistry October 2008 105

‘I can now finalise my substructure in the lab and start to be creative with much
more freedom and expression than ever before. I can fire my titanium porcelain
onto some PIBs and I can use Gradia composites on others. I am making single
unit substructures through to full arches, and they can be made in zirconia as well
as in titanium.’
next casting ring is more accurate and
less time-consuming. In bridge cases,
where the metal needs actually to
touch on another at the welding join,
it will require a much higher level of
skill than conventional soldering in
order to ensure that, by adding and
subtracting to the join, it touches
exactly. All that sounds troublesome
and time-consuming to me. But there
again, laser-welding does have its place,
because it is one of the only methods
that work with titanium. And even
now, with experience born out of 12
years of marriage, a little voice is saying
in my head, ‘Be constructive; do not
just criticise.’
We knew it all along
So there it was all along, the answer
right from the beginning. As
technicians, we all do it every day and
all the time, on nearly every coping
we make. We mill it and trim it. No
soldering or welding in any shape,
way or form. No heat expansion or
contraction, no gaps to fill, no flux to
contaminate, no technique-sensitive
preliminary procedures, no material
cost. Just hours and hours of milling
and cutting, until our fingers fall off
and we join the exhausted heap of
solderers and laser-welders of time
gone by.
I am sorry and afraid that my story
is not over yet! I have been over-seeing
this method by using cad-cam and a
milling machine in the construction of
passive units, using the Procera All-in-
One system for the last four years. (In
an attempt to save my fingers and it
is so easy.) Yet, it does not seem to be
part of our everyday routine in every
laboratory and dental practice. It is
being challenged by other less accurate
products on the market. Why doesn’t
anyone seem to be talking about it? So
I wondered; am I missing out on the
miracle of laser-welding? Might I need
to buy one?
I used the Noble Biocare open tray
technique, in which screw-retained
impression copings are connected
and duralayed to one another, and
a viscous, hard-bodied accurate
impression material is injected
into a custom-made tray. In this
impression, the soft tissue solid model
is poured, and on this a diagnostic
try-in is created, using metal temporary
cylinders that are connected together
in acrylic. I then finish the framework
in acrylic and Sweden does the rest. My
reward is an engaging (single-units),
non-engaging zirconia or titanium, allin-one
milled structure that fits. And,
boy does it fit!
This fit (see Figure 2) is due to its
unsurpassed ability to contact-measure
simple, pure, implant replicas of given
dimensions, and then laser-scanning
the external framework, which does not
need the accuracy of contact-scanning.
Together this arithmetical equation
is re-enacted with milling tools,
transforming a solid homogeneous
titanium block into dentistry at its best.
I welcome this form of technology in
my profession. It ensures for the patient
what would be unachievable by man.
I can now finalise my substructure
in the lab and start to be creative with
much more freedom and expression
than ever before. I can fire my titanium
porcelain onto some PIBs and I can
use Gradia composites on others. I
am making single unit substructures
through to full arches, and they can
be made in zirconia as well as in
titanium. The only limitation with
this phenomenal product is that, with
screw-retained substructures, you are
unable to deviate more than 20 degrees
from the implant screw-hole opening.
(You can also use the multi-unit
abutment for Noble Biocare implants
that can correct an axial alignment of
the implant for the desired positioning
of the screw-channel, etc — the list
goes on.)
We are, however, able to work
around most implants’ head-placement,
as implants at bone level mean that the
point of rotation allows for a marked
relocating potential of the access hole.
This deviation, in measure, is about
7mm at 2cm from axis of rotation.
The access-hole is smaller than some
rivals, as the screwdriver access is the
thickness of the screw-head, rather
than the screwdriver used. Using a
composite case, if you want the screw
to be integral in the framework, the
hole is much more discreet because the
screwdriver shaft is only 1.5mm thick.
What I like most about the PIB
method is the freedom of aesthetics.
It is, at last, a solution that I would
use in my own mouth instead of a
denture. As a technician for 20 years,
I have always maintained that the
aesthetics of full arch implants and
their emergence profiles with long
root effects do nothing for me. Some
dentists say, ‘It does not matter what’s
under your lip because you cannot see
it.’ I suspect that many patients, given
the choice, would actually have existing
work redone for better tissue aesthetics.
We have the materials and we have
the skills. All we need to do is educate
dentists, technicians and patients, and
encourage them to use it.
PIB benefits
The advantages of PIBs are manifold.
106 Private Dentistry October 2008

They:
• Have a passive accurate fit, perfect to
the model implant analogs
• Have the best aesthetic potential on
the market
• At implant level are 40% cheaper than
traditional methods to date, as the parts
are included in the prosthesis
• Have no more yellow gold and other
potential metal allergies
• Are made in the same metal as the
implants themselves (no galvanic
potential)
• Are capable of more combinations of
reconstructive solutions over any other
product on the market
• Are able to move access channel-holes
to enhance the aesthetic result
• Can be covered with conventional
crown and bridge work
Can be made in:
• Procera Implant Bridge Zirconia (now
up to 14 units)
• Procera Implant Bridge Titanium
• Procera Implant Bridge Titanium for
other implant systems
• Camlog, Astra Tech and Ankylos
• Enabled through a new Multi-
Unit Abutment (the new Multi-Unit
Abutment fits with the following
implant systems: Camlog 3.3, 3.8, 4.3,
5.0, 6.0; AstraTech 3.5ST, 4.0ST, 4.5ST,
5.0ST; Ankylos 3.5, 4.5, 5.5, 7.0)
• Can be used with a wider range of
implant systems
• Already fits Straumann Regular Neck
4.8mm and Wide Neck 6.5mm.
To sum up
PIBs tick all the criteria in modern
dentistry, both functionally and
aesthetically, and their longevity record
is good. Requiring yearly maintenance,
they are easy to clean, simple to
repair, cost-effective and aesthetically
predictable. Every time one is sent
to me, I am amazed at the fit; and I
think that, in the future, they may
well prove to be a primary tool in our
profession, just as the primary colours
are the foundation of all colours in
the rainbow. As I try on yet another
framework, and look under my 20 times
magnification, I marvel that the miracle
has happened again. No more waiting
for the answer; simply a feeling of great
thankfulness, as I look back to the good
old days and remember when I tried to
solder or laser-weld that large case for
Mrs Maxilla, and how long it took.
And the next step? Stem cell
technologies, successful, predictable,
soft tissue and bone grafts? What an
exciting thought! And what good news
for the patient — who must always be
our first consideration. PD
Comments to pd@fmc.co.uk
TJ Nicolas, RDT NHD RSA is winner of
dental technician of the year 2007-2008.
Private Dentistry October 2008 107