is the most important part of root canal therapy. Finding the culprit
tooth and finding out why it needs RCT are vital to success. The
radiograph will help you with the tooth anatomy and help you decide how
you should approach each tooth depending on what you see.
In the first case, a patient presented with
a fistula that was traced to the apical third of tooth #5 (Figure 1).
There is evidence on the x-ray that #5 has a periapical lucency.
The gutta percha, however, did not go down to the apex but stopped short
by 4 mm. This told me that something else was causing the fistula
and not the area at the apex. The two possibilities that can result
in this type of fistula tracing are a lateral canal or a fracture of the
root at that level. The patient had no history of facial trauma and
there was no evidence of a horizontal fracture on the radiograph.
The only other explanation was a lateral canal or a vertical crack from
occlussal trauma. The vertical crack was ruled out once access was
attained. The diagnosis for tooth #5 was necrotic pulp with periapical
lucency and a draining fistula caused by a lateral canal. The canals
were instrumented using the SafeSiders® technique. I made sure
to soak the canal well with NaOCl during the instrumentation process to
remove the necrotic tissue inside the lateral canal. EDTA was used
to remove the smear layer and to open up the tubules. The canals
were sealed using EZ-Fill® cement with a single-cone gutta percha for
each canal. In Figure 2, you can see the puff of cement about 3?4
mm from the apex where the lateral canal is located.
The next case involved a curved mesiobuccal
root on tooth #15. After looking at the radiograph of the culprit
tooth (Figure 3), I knew that care and patience would be needed in order
to get a good result. I have found that one has to deviate from the
SafeSiders sequence a little bit when instrumenting this type of curved
canal. Take your time and use new reamers when engaging such a sharp
curve. Throw away any reamers that have unwound or are crooked at
the tip. Use a reciprocating handpiece to reduce the stress on the
reamers. First get the reamers down to the apex to make sure that
the canal path is clear. Then instrument the canal to a #20 reamer.
To make sure that there is no debris blockage, you may have to go back
to a smaller size after every larger instrument you use. Next go
in with a #2 Gates Glidden to open up the canal. The flexibility
of the GG will take the initial part of the curve better than the Peeso
reamer. Go back and irrigate the canals and reinstrument with the
#10 reamers to make sure that there is patency. Now go in with a
#2 Peeso reamer and let it follow the path of the GG. It will not
go in too far because of the sharp curve. However, this widening
of the coronal portion of the canal will allow the #25-30 reamers to reach
the apex with less stress. Once you open up the canal to the #30
reamer, go back in with the Gates Glidden. You will be able to get
it down a little farther. Make sure you irrigate and reinstrument
with the #10 reamer after every large reamer you instrument with.
Now take the 30/.04 NiTi and instrument down to the apex. Follow
that with 25/.06 and 25/.08 NiTi. Take your time and do it slowly.
Patience is the key when shaping a sharp curve like this one. Once
the canal is shaped, fill it with EZ-Fill cement and a medium size gutta
percha point as seen in Figure 4.
The last case proves that a single-visit root
canal treatment of a chronic necrotic tooth can be as successful as two
visits with Ca(OH)2 interim. Tooth #19 had a periapical lesion wrapped
around both roots (Figure 5). The tooth was asymptomatic and was
found under radiographic examination. Root canal was done using the
SafeSiders technique with NaOCl irrigant. The canals were rinsed
with EDTA to remove the smear layer, and chlorhexidine was used to disinfect
for two minutes. The canals were filled with EZ-Fill cement and gutta
percha as seen in Figure 6. The six-month recall showed complete
healing (Figure 7).
November - December 2006
FIGURE 1: Showing a fistula
that was traced to the apical third of tooth #5.
FIGURE 2: Showing the puff
of cement about 34 mm from the apex where the lateral canal is located.
FIGURE 3: Showing a curved
mesiobuccal root on tooth #15.
FIGURE 4: Showing the canal
filled with EZ-Fill cement and a medium size gutta percha point.
FIGURE 5: Tooth #19 with
a periapical lesion wrapped around both roots.
FIGURE 6: The canals filled
with EZ-Fill cement and gutta percha.
FIGURE 7: Taken at the six-month