The LightSpeed root canal instrumentation system - Wiley Online ...

Endodontic Topics 2005, 10, 148–150
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Copyright r Blackwell Munksgaard
ENDODONTIC TOPICS 2005
1601-1538
The LightSpeed root canal
instrumentation system
E. STEVE SENIA & WILLIAM L.WILDEY
The LightSpeed s root canal instrument design is unique in that it has a non-cutting pilot, a very short blade and a
flexible, non-cutting shaft. This allows negotiating 3-dimensional canal curvatures with saftey and precision. The
technique is simple, predictable and similar for all canals. As its name implies, the SimpliFill s obturation technique
is simple to use and unique in that it is the only carrier-based obturation system that does not leave the carrier in the
canal. It consists of a 5 mm piece of gutta percha (also available in Resilon) that matches the size of the LightSpeed
preparation for a predictable fit. Backfilling (coronal to the Apical Plug) can be done many different ways. This
article describes a backfilling technique that is fast and simple utilizing a syringe and small gauge needle.
Background
The apical area of the root canal system is a critical
region that presents the greatest challenge for instruments
to clean and irrigants to penetrate. The quality of
cleaning depends on the pre-instrumentation size of
the canal and the size of the largest apical instrument
used (Master Apical Rotary (MAR)/MAF). Instruments
smaller than the original apical canal diameter
cannot remove infected dentine and it is not likely that
depth of irrigation needle penetration and irrigant
volume will be adequate, in particular in small canals.
Design of the LightSpeed (LS)
instrument
LS instruments (LightSpeed Technology Inc., San
Antonio, TX, USA) are designed for apical preparation
while providing the correct shape for a quality
obturation. They have a short cutting blade (0.25–
2 mm in length), with a non-cutting pilot tip and a
smooth, flexible shaft (Fig. 1). They can negotiate even
difficult curvatures and cut dentine from canal walls
without fear of coronal over-enlargement. There are
more instruments in the LS System because the apical
diameters of canals vary widely.
The LS technique essentially follows the same steps
for all teeth. A handpiece (preferably low torque and
cordless), rotating at 2000 r.p.m. is required; all one
needs to do is gently advance LS to the desired length.
Technique
LS instruments should be used only after preparing a
standard access cavity, flaring coronally (not with LS),
Fig. 1. The LightSpeed root canal instrument has a noncutting
tip and a short blade. The shaft is smooth, nontapered
and very flexible. Length measuring rings are
located on the shank.
Table 1. Before using LightSpeed instruments
Prepare access
Flare coronal third
Determine working length
Explore canal and establish patency with a size #15 K-type
file
Broach, when possible
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The LightSpeed system
Table 2. Instrumentation – 5 steps
1. Gauge canal to determine its minimum diameter (FLSB)
2. Begin apical instrumentation with the FLSB size and end
with the Master Apical Rotary (MAR) size (12 ‘pecks’)
3. Instrument 4 mm short of WL with the next larger size
4. Instrument middle third with three to four larger sizes
5. Recapitulate to WL with the MAR
Table 3. Handpiece movements
Enter canal rotating; advance slowly to resistance
From resistance go to WL with an advance/withdraw
motion (pecks)
At WL immediately withdraw from the canal (rotating)
Always use a light touch
Table 4. Apical cleaning (FLSB vs. MAR)
Gauging (sizing) finds the smallest diameter (FLSB) of the
canal
Gauging is done by hand with LightSpeed instruments
Rotary instrumentation begins with the gauging size
Sequentially larger sizes clean more of the canal wall
The MAR size ends instrumentation (cleans all canal walls;
use 12 Pecks Rule)
Fig. 2. SimpliFill is a solid, 5 mm tapered gutta percha
cone attached to a stainless-steel carrier. The carrier is
removed from the canal after it condenses the cone to
working length (with sealer). The middle and coronal
parts of the canal are obturated with the technique of
choice.
obtaining working length (WL) and assuring canal patency
with at least a loose fitting size 15 K-type file. Canals are
broached when possible to remove pulp tissue (Table 1).
Step 1: The original apical canal diameter is gauged
(sized) with LS instruments by hand (Table 2). Gauging
Fig. 3. (a) Pre-treatment radiograph of mandibular left
second molar. (b) Post-obturation radiograph: The ML,
MB and D canals were obturated apically with SimpliFill
GP Plugs (#60) and AH Plus sealer. The middle and
coronal thirds of all canals were obturated with GP and
AH Plus sealer. (c) One-year follow-up radiograph. (Case
by Dr William L. Wildey.)
measures the smallest diameter of a canal with LS using
moderate apical force. Begin with a small instrument and
test whether it goes to WL. If it does then it is smaller
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Senia & Wildey
than the canal diameter. Therefore, try sequentially
larger instruments until one binds before reaching WL.
This instrument is used in the handpiece. However, if
the small instrument selected binds short of WL it is too
large and you should try sequentially smaller sizes until
one goes to WL. You will find that the next larger size
will bind before WL and that is the size used in the
handpiece. With such gauging the instrument size
closely approximates the smallest size of the canal.
We call this instrument the FLSB because it is the First
LS instrument size to Bind before reaching WL. Note
that this size is used to begin (not end) canal
preparation.
Step 2: Begin mechanical instrumentation with the
FLSB. All LS instruments are used the same way; with a
slow, continuous apical movement until the blade
binds, a momentary pause, and then advancing it to WL
with intermittent or ‘pecking’ motions (a ‘peck’ is a
short inward and a slight withdrawal motion) (Table 3).
The number of pecks required to reach WL will increase
as instrument size increases because more wall dentine
is cut. The instrument size that, of itself, requires 12
pecks or more (‘12 pecks rule’) to advance from where
it first binds (and pecking begins) until reaching WL is
called the MAR. The MAR is the ‘correct’ instrument
size for proper apical cleaning (Table 4). Smaller sizes
do not clean as well whereas larger sizes may cause overenlargement
and weakening of root structure.
Step 3: The next larger size is used to instrument to a
length that is 4 mm short of WL using a pecking
motion but without counting pecks. This completes
cleaning and shaping the apical 5 mm of the canal for
obturation with a similarly shaped 5 mm SimpliFill
Gutta Percha Plug (LightSpeed Technology Inc., San
Antonio, TX, USA) (Fig. 2).
Step 4: The middle third of the canal is instrumented
with sequentially larger full-size LS instruments (there
is no need to use the half-sizes). When an instrument
no longer advances easily with light pecks, it is
withdrawn from the canal and replaced with the next
larger full size. This sequence continues until reaching a
size that does not easily advance beyond the coronal
third of the canal. Mid-root is usually prepared with
three or four LS instruments.
Step 5: Recapitulate to WL with the MAR. This
ensures a clear path for filling.
Conclusion
Rotary instrumentation is an exciting and valuable
advancement in canal preparation. Better apical cleaning,
the essence of successful therapy, is now possible
with the latest generation of rotary nickel–titanium
instruments (Fig. 3).
Acknowledgements
The assistance of Mr Steven Senia, BSIE, MBA is gratefully
acknowledged.
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