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Source: Pathways of Pulp 10th Ed (p.190)
March 16, 2013
Middle Mesial Canal: Mandibular First Molar
Source: Pathway of Pulp 10th Ed. (p. 209)
In a
study of 760 mandibular molars, Fabra found that 20 (2.6%) had three canals in
the mesial root. In 13 of these (65%) the third canal joined the mesiobuccal
canal in the apical third of the root and in 6 (30%) they converged with the
mesiolingual canal, also in the apical third; the third canal ended as an
independent canal in only 1 case. Many authors agree on the presence of three
foramena in the mesial root but few report three independent canals, which
presents itself as a rare anatomical variant. Walker cites 3 canals in the
mesial root of the mandibular first molars as an infrequent ocurrence. Goel
notes that the mesial root of permanent mandibular first molars presented two
foramena in 60% of the specimens they examined, 6,7% had three and 3.3% even
had four. In early studies by Hess, only 1 out of 55 teeth presented 2 distal
roots and 5 canals did not appear in any of the teeth. However, many other
authors confirm the hypothesis of a third canal in the mesial root of the
permanent mandibular first molars According to Mortman, the third mesial canal
is not an extra canal but rather the sequelae of instrumenting the isthmus
between the mesiobuccal and mesiolingual canals. The isthmus is a narrow
connection between two root canals that contains pulp tissue. In clinical
practice, this isthmus is important in the conventional treatment of canals and
in periapical surgery. In both cases it can lead to failure because it makes
the canals very difficult to shape. An isthmus is located in between 54% and 89%
of cases, most frequently between 4 mm and 6 mm from the apical foramen. The
studies that examine series of cross-sections taken at different distances from
the apex observe that isthmuses mainly occur at 3-5 mm from the apex. The
prevalence and types of isthmus that can be identified in first molars by
endoscopic examination during periapical surgery are as follows for the mesial
root of the mandibular first molar: in a sample of 52 mesial roots, a canal
with no isthmus was found in 3 cases (6%), two canals with no isthmus in 6
(11%) and two canals with isthmus in 43 (83%). Read more here.
Source: Navarro et al. (2007)
March 10, 2013
The Root Canal Anatomy Project: Two Years Online
Begun formally in 2011, The Root Canal Anatomy Project completed two years online on 5th of March. This blog was developed in the Laboratory of Endodontics of Ribeirao Preto Dental School - University of Sao Paulo - with noncommercial and educational purposes. During this period, the blog was visited by people from 163 different countries with more than 221,000 page views. The videos were watched more that 54,000 times and the material was downloaded more than 6,000 times. Considering that root canal anatomy is a very specific subject in the endodontic field, we believe that the blog is achieving its goals. Thank you for your support and stay tuned for updates.
Root Canal Anatomy Project
Statistics From March 2011 to March 2013
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