Let's talk about canal preparation featuring ProTaper Gold®.
Now it's important to know that ProTaper Gold
has exactly the same geometries as its predecessor, ProTaper® Universal.
And it has a convex then triangular cross-section and a centered mass of rotation.
Let's take a look.
Let's look at the family of instruments.
You can see if you divide it right down the middle,
there are three shapers: SX,
Shaper One, Shaper Two
and there are three finishers:
Finisher One, Two, and Three.
There's actually two more instruments not shown.
That would be the F4 and the F5.
The F4 is a 40/.06 and the F5 is a 50/.05.
I'm showing the ones that are actually utilized the most internationally
by a vast number of dentists.
So let's focus on these.
Notice again that there's variable tapers .
None of these instruments have a fixed taper over their active portion.
And, of course, when this came out back in 2001,
it was absolutely innovative and the first in the world that had this design feature.
Again like ProGlider®, ProTaper Gold family of instruments all,
that means each one of them, runs at 300 rpms
and at a torque of between 4 to 5.2 Newton centimeters.
Again, these instruments were tested from 1995 to the launch in 2001.
That means there was a lot of engineering.
There was validation,
field testing and clinical trials.
It was all done at 4 to 5.2 Newton centimeters
and these papers or citations that you will see
are validating the high torque,
so don't turn the torque down unless you want to experience
more broken instruments.
And here's another great citation by Berutti, et al,
showing the importance of high torque to have saved instruments.
Again, low torque leads to more broken instruments.
It's good to use low torque on fixed tapered instruments.
The critical distinction clinically is, these are not fixed tapered instruments.
So, it's important to note that our shapers
work up in the body, the coronal middle one third.
The shapers are basically
not working in the apical 1/3 of roots.
They're to follow the glide path.
That means the workload then, per usual,
is pushed up onto the bigger stronger and more efficient blades.
You've seen SX before
and it has 9 changing,
increasing percentage taper over its active portion.
The S1 has 12 changing progressively increasing tapers over its active portion,
and S2 has 9 changing percentage tapers over its active portion.
It's important to note, we looked at the
Shaper X in terms of D6, D7, D8, D9
and at D9 we said it was 1.1 millimeter in its cross-section.
Listen carefully.
S1 and S2 are about 1.1 millimeters at D16,
so in the clinical scenario where S1 and S2 achieve length,
especially in shorter anatomical roots,
you can imagine the most important shaping blades are up in the access cavity
and can't get below the orifice.
In this instance,
you would use SX because it has compressed geometries
and at only D9 is as big as S1 and S2.
That's a critical distinction in the family of shaping files.
I want to have you really say out loud as you listen along, "Brush, follow."
We've been teaching this for more than a decade,
16 or 17 years to be exact,
and in workshops the colleague that brushes deliberately and intentionally
on the outer wall,
and in furcated teeth, away from furcal danger,
notices that when they brush laterally,
those bigger, increasing percentage tapered blades,
progressively advance deeper into the canal.
So brushing's a big secret.
We don't brush
over and over and over. Just a few little deliberate, short,
intentional brushstrokes on the outer wall, away from furcal danger
allows the instrument to run towards length.
So brush, follow, brush, follow, and brush, follow.
Now the finishers have decreasing percentage tapers over their active portion
and that is so we don't continue to progressively increase
the dimensions of the canal in the coronal and middle one-third.
Now this is an important concept.
Colleagues around the world
oftentimes want to increase their terminal diameter of the canal
and in doing so with fixed tapered files,
they're obligated to continue shaping
the entire length of the canal.
In this concept, having shapers and finishers,
finishers allow us to increase the D0 diameter, an apical 1/3 taper,
without continuing to pre-enlarge the body of the canal.
So in the ISO world, we have color bands on the handles.
As you'd expect, yellow corresponds to two tenths of a millimeter at D0 with a 7% fixed taper.
But it's only 7% in the apical three millimeters.
Then it has decreasing percentage tapers
so that we don't continue to shape.
And the red is a 25/.08, in the 30's, a 30/.09.
And again, if we look at the family of instruments together,
we can see that the finishers then
do the apical 1/3, whereas the shapers did the body.
And now it's just backwards.
When we use this, in your head, play a mental game and say, "Follow, brush."
So let the finishers run through the pre-enlarged canal
and as they begin to engage dentin,
pull up a little bit, a stop or two, and that's brushing.
Brushing allows the instrument to run, so we say, "Follow, brush."
So the shapers just 'brush, follow'.
The finishers is 'follow, brush'
and together we have a family of instruments
that blends the deep shape of the finishers
into the body of the canal that was produced and englarged with the shaping files.