ENDODONTIC ANATOMY
I/ Introduction
“Knowledge of anatomy is the essential foundation of the sciences which apply to matter
living being of man.”
Any endodontic treatment begins with the study of X-rays which provide information on the internal anatomy of the tooth.
Many researchers have shown great ingenuity in their attempts to better understand endodontic canal anatomy.
In endodontics, pulp disorders, periapical complications of these diseases or their endoperiodontal repercussions require, for the understanding of their clinical manifestation and the effectiveness of the therapeutic procedure, a perfect knowledge of pulpo-radicular anatomy.
III/ Classifications of root canals
- Classification of DE DEUS 1975
- WEINE classification
3- VERTUCCI classification
Type I: single canal from pulp chamber to apex
Type II or “2-1”: 2 separate canals starting from the pulp chamber and joining to exit as 1 canal
Type III or “1-2-1”: 1 canal leaving the pulp chamber, dividing into 2 canals which join to exit as 1 canal
Type IV: 2 distinct canals from the pulp chamber to the apex.
Type V or “1-2”: 1 canal leaving the pulp chamber and dividing shortly before the apex into 2 separate canals with 2 apical foramina
Type VI or “2-1-2”: 2 separate canals leaving the pulp chamber, uniting in the root and dividing near the apex to exit as 2 separate canals
Type VII or “1-2-1-2”: 1 canal leaving the pulp chamber, dividing then reuniting in the root to finally redivide near the apex into 2 separate canals.
Type VIII: 3 separate canals from the pulp chamber to the apex
P.Machtou’s classification:
Type A configuration : single channel
Type B configuration: single canal with apical bifurcation
Type C configuration: Coalescence of 2 canal entrances associated with an apical bifurcation
Type D configuration: Apical union of two canals with a common foramen.
Type E configuration: a root can contain two channels with completely independent paths.
Type F Configuration: Channel having an arc-shaped configuration.
III/ Endodontic anatomy:
1. ANTERIOR TEETH (incisors and canines)
Incisors: The pulp chamber of the incisors appears wide and may have a mesial horn and a distal horn
Canines: The pulp chamber is pointed towards the free edge. It widens in the cervical region. Usually the vestibular contour and the lingual contour are convex.
They give a “biconvex lens” appearance
Root canals:
Anterior teeth usually have a single root. The number of root canals for these anterior teeth is a single canal (type I).
2 The posterior teeth:
a. Premolars : The pulp chamber shows a vestibular horn and a lingual horn, separated by a concavity oriented towards the occlusal face.
The buccal horn is usually the largest. The width of the pulp chamber is approximately the same from the horns to the cameral floor.
Root canals
1st upper premolars : most often have two roots and two canals (one in the vestibular root, the other in the palatal root)
The canals of these two roots respond to a type I configuration
Upper 2nd premolars: often have only one root, but may have one or two canals. The average incidence of having two canals is 50% (type II or III)
Lower 1st premolars and 2nd premolars: have one root and one root canal (type I)
Molars : The pulp chamber of the molars:
As with all cuspid teeth, the pulp horns of molars are located on the roof of the pulp chamber, below each cusp.
The pulp chamber of the upper molars is wider buccally-palatally than mesio-distally (like the crown) and usually narrows near the floor of the pulp chamber.
On lower molars, the pulp chamber is wider mesio-distally than vestibulo-lingually.
Root canals
The 1st upper molar: most often has three roots, but can have 3 or 4 canals.
The mesio-vestibular root has two canals in 90% of cases, one of which is located in a more vestibular position within this root: this is the mesio-vestibular canal. The other is in a more lingual position, this is the mesio-lingual canal (type III configuration).
The disto-vestibular root has the thinnest canal. The most massive and longest palatine root, its canal is wide.
The 2nd upper molar: Has 3 roots and 3 canals
Upper third molars usually have three canals
Lower molars : often have two roots (one mesial and one distal) and three canals two in the mesial root and one canal in the distal root
The mesial root has two type III canals in 60% of cases or a type II canal system in 40% of cases.
The second lower molar; a single mesial canal is much more common (40 to 45%) The distal pulp horn is absent The mesial canals are clearly less divergent than on the 1st molar
The lower 3rd molars have only two canals
However, the 3rd molars can have very different shapes.
Temporary teeth
Temporary central incisor
The pulp volume is large, the mesio-distal diameter is considerably larger than the vestibulo-lingual diameter On a mesio-distal cut
The lateral incisor ; In the incisal part, the mesio-distal diameter is considerably larger than the vestibulo-lingual diameter
The canine ; The pulp cavity follows the general anatomy of the tooth. The pulp horn projects
towards the cusp tip and sometimes has two additional horns.
The temporary molar ; It has three or four horns, the most important of which is the horn
mesiovestibular
They present more morphological variations than permanent canals
Mandibular temporary central and lateral incisor;
The pulp cavity follows the external contours of the tooth. In the cervical region, the vestibulolingual diameter is slightly larger than the mesiodistal diameter
A horizontal section in the cervical region shows an ovoid shape with a large vestibulolingual axis.
Lower canine ; In the cervical region, the vestibulo-lingual diameter of the pulp chamber is larger than the mesio-distal diameter
First temporary molar : The pulp cavity consists of a pulp chamber with four horns (which correspond to the cusps) and two or three root canals (one or two mesial canals and one distal canal).
It has four horns that correspond to the four cusps. The mesiovestibular horn is the most important
The second lower molar ; The pulp chamber occupies the central part of the coronal cervical third and the radicular cervical third. The vestibulolingual diameter of the pulp chamber is less important than the mesiodistal diameter.
There may be one to three canals in the mesial root , one canal is located in the distal root. On a horizontal section, the distal root has a figure-of-eight shaped section.
ENDODONTIC ANATOMY
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