ALWAYS ENJOY lecturing in Italy because the people are so nice and I have
never had a bad meal yet! (See Figure 1.) I recently gave lectures
in Torino, Milano, and Padua. As usual, you can lecture all day but
once the dentist picks up the reciprocating handpiece and actually instruments
a tooth the response is always fabulous. Figure 2 shows the hands-on
group learning the SafeSiders® technique in Torino. Nothing beats actually
working on teeth. Figure 3 shows some extreme coaching, one-on-one, to
get the SafeSiders technique down pat. In Figure 4 you can see the
youngest participant ever. She actually did very well. Who
needs dental school!
During these hands-on courses, whenever someone
is doing a maxillary molar we try to find the MB2. Without loupes and a
microscope, this is no easy task. It has been documented that with
a microscope the incidence of finding the MB2 goes way up. Recently, on
Dentaltown there was some discussion about how often the MB2 is present
in maxillary molars. There are many articles in the literature on
this topic, and they vary greatly. Recently an excellent review was
published: Cleghorn B, Christie W, and Dong C. Root and Root Canal Morphology
of the Human Permanent Maxillary First Molar: A Literature Review, J
The review states that these studies found
many factors that contribute to the variation. Data from specialty
endodontic practices may not represent the frequency in a general population.
Design of the Study
In the lab, different cleaning methods and
radiographic methods will lead to different results. The authors
go on to mention many other variations in the studies, which contribute
to varying results.
There can also be variations in the number
of canals reported because of the authorsí definition of what constitutes
a canal. I personally think that this is one of the largest sources
of error. The Cleghorn review states, ďA separate canal is
defined in some studies as a separate orifice found on the floor of the
pulp chamber, two instruments placed into two MB canals simultaneously
to a minimum depth of 16 mm from the cusp of an intact tooth, one that
can be instrumented to a depth of 3 to 4 mm, or a treatable canal in retrospective
clinical studies. Other studies fail to provide a clear definition
of what defines a canal in their reported data. The review also reports
that fewer canals were found in the MB root because of increasing age and
This review contained the most data on the
canal morphology of the mesiobuccal root, with a total of 8,399 teeth from
34 studies. The incidence of two canals in the mesiobuccal root was
56.8 percent, and of one canal was 43.1 percent in a weighted average of
all reported studies. The incidence of two canals in the MB root
was higher in laboratory studies (60.5 percent) compared with clinical
studies (54.7 percent). Less variation was found in the distobuccal
and palatal roots, and the results were reported from fourteen studies
consisting of 2,576 teeth. One canal was found in the distobuccal root
in 98.3 percent of teeth, whereas the palatal root had one canal in more
than 99 percent of the teeth studied.
Keep looking for that MB2 canal; it seems to be there
almost 60 percent of the time.
The mesiobuccal root of the maxillary first molar contains a double root
canal system more often than a single canal, in most studies.
The two-canal system of the MB root of the maxillary first molar has a
single apical foramen roughly twice as often in proportion to the two-canal
and two-foramen morphology, in weighted studies.
January - March 2007
FIGURE 1: Allan relaxing
with a great cappuccino in Florence.
FIGURE 2: The hands-on group
learning the SafeSiders technique in Torino.
FIGURE 3: One-on-one coaching.
FIGURE 4: The youngest participant.