Anatomy of canines and premolars (ENDO)

tooth morphology ,, access cavity ,, canal configuration
Done by : Weam Mahmoud
Future dentist ^_^

1. Done By : WeamMahmoud
Faroun
Fourth year dental student
submitted to : DR.DavidAyyad
Summer semester 2017-2018
Anatomy Of Canines
& Premolars

2. Maxillary canine

3. •average time of eruption, 10 to 12 years
•average age of calcifcation, 13 to 15 years
•average length, 26.5 mm (Longest tooth )
•root curvature (most common to least common):
distal, straight, labial.

4. Maxillary canine
The root canal system of the maxillary canine is
similar in many ways to that of the maxillary incisors.
A major difference is that
1.it is wider labiolinguallythan mesiodistally.
2.Another difference is that it has no pulp horns.
Its smallest pointed incisaledge corresponds to the
single cusp.
The pulp chamber outline at the CEJ is oval.
A lingual shoulder is present, which may prevent
shaping and cleaning of the root canal in its lingual
dimension. From this point, the root canal remains
oval until it approaches the apical third of the root,
where it becomes constricted.

5. Because of this oval shape, the clinician must
take care to circumferentially file labiallyand
palatallyto shape and clean the canal properly.
Usually one root canal is present, although two
canals have been reported
The thin buccalbone over the canine eminence
often disintegrates, and fenestration is an
occasional finding.

6. The external access outline form is oval or slot
shaped because no mesialor distal pulp horns
are present
The incisogingivaldimension is determined by
straight-line access factors and removal of the
lingual shoulder.
The incisalextension often approaches to
within 2 to 3 mm of the incisaledge to allow for
straight-line access.

7. The incisalwall meets the lingual surface of the
canine in a butt joint to provide adequate
thickness for restorative material, because this
tooth is heavily involved in excursive occlusal
guidance and function.
All internal walls funnel to the orifice.
As attrition occurs, the chamber appears to move
more incisallybecause of the loss of structure.

10. Mandibularcanine

11. Mandibularcanine
Average time of eruption, 9 to 10 years
average age of calcifcation, 13 years
average length22.5 mm.
root curvature (most common to least common):
straight, distal, labial.

12. MandibularCanine
The root canal system of the mandibularcanine is
very similar to that of the maxillary canine except
that :
1.the dimensions are smaller
2.the root and root canal outlines are narrower in
the mesiodistaldimension
3.the mandibularcanine occasionally has two
roots and two root canals located labiallyand
lingually

14. The root canal of the mandibularcuspidis narrow
mesiodistallybut usually very broad
buccolingually.
A lingual shoulder must be removed to gain
access to the lingual wall of the root canal or to
the entrance of a second canal.
The lingual wall is almost slitlikecompared with
the larger buccalwall, which makes the canal a
challenge to shape and clean.
In older patients, where there is deposition of
secondarydentine, it becomes necessary to
incorporate the incisaledgeintothe access cavity
for straight line access.

15. The access cavity for the mandibularcanine is oval
or slot shaped
The mesiodistalwidth corresponds to the mesiodistal
width of the pulp chamber.
The incisalextension can approach the incisaledge
of the
tooth for straight-line access, and the gingival
extension must
penetrate the cingulumto allow a search for a possible
lingual
canal.
As with the mandibularincisors, butt joint relationships
between internal walls and the lingual surface are
not necessary.

18. Maxillary first premolar

19. average time of eruption, 10 to 11years
average age of calcifcation, 13 to 14 years
average length, 20.6 mm.
root curvature (most common to least common):
buccalroot—lingual, straight, buccal; palatal
root—straight, buccal, distal
single root—straight, distal, buccal.

20. The majority have two root canals regardless of
the number of roots.
Ethnicity plays a factor in that Asian people have
a higher incidence of one canal than do other
ethnic groups.
A furcationgroove or developmental depression
on the palatal aspect of the buccalroot is
another anatomic feature.
This groove may pose a risk to endodontic and
prosthodontictreatment of this tooth. At the
deepest part of the invagination, the average
dentin thickness was found to be 0.81 mm.

21. The pulp chamber wider buccolinguallythan
mesiodistally.
In the buccolingualdimension the chamber outline
shows a buccaland a palatal pulp horn. The
buccalpulp horn usually is larger.
From the occlusallevel the chamber maintains a
similar width to the floor, which is located just apical
to the cervical line.
The palatal orifceis slightly larger than the buccal
orifce.

23. In cross-section at the CEJ, the palatal orifceis
wider buccolinguallyand kidney shaped because
of its mesialconcavity.
From the floor, two root canals take on a round
shape at midrootand rapidly taper to their apices,
usually ending in extremely narrow, curved root
canals.
The palatal canal usually is slightly larger than
thebuccalcanal.

24. The maxillary first premolar may have one, two, or
three roots and canals; it most often has two.
If two canals are present, they are labeled buccal
and palatal
three root canals are designated mesiobuccal,
distobuccal, and palatal.
The roots are considerably shorter and thinner than
in the canines.

26. In double-rooted teeth the roots most often are
the same length.
The buccalroot can fenestrate through the bone,
leading to the same problems that arise with
canines (i.e., inaccurate apex location, chronic
posttreatmentsensitivity to palpation over the
apex, and an increased risk of an irrigation
accident).

27. The access preparation is oval or slot shaped also
wide buccolingually, narrow mesiodistally, and centered
mesiodistallybetween the cusp tips.
In fact, the mesiodistalwidth should correspond to the
mesiodistalwidth of the pulp chamber.
The buccalextension typically is two thirds to three
fourths up the buccalcusp incline. The palatal
extension is approximately halfway up the palatal
cusp incline.
The buccaland palatal walls funnel directly into the
orifces.
Because of the mesialconcavity of the root, the clinician
must take care not to overextend the preparation in that
direction, as this could result in perforation.
When three canals are present, the external outline form
becomes triangular with the base on the buccalaspect

30. Maxillary second premolar

31. Maxillary second premolar
Average time of eruption, 10 to 12 years
average age of calcifcation, 13 to 15 years
average length: 21.5 mm.
root curvature (most common to least
common): distal, bayonet, buccal, straight.

32. The root canal system of the maxillary second
premolar is wider buccolinguallythan mesiodistally.
This tooth may have one, two, or three roots and
canals
Two or three canals can occur in a single root.
The mesiodistaland buccolingualaspects of the pulp
chamber are similar to those of the first premolar.
A buccaland a palatal pulp horn are present; the
buccalpulp horn is larger.
A single root is oval and wider buccolinguallythan
mesiodistally.
The canal(s) remain oval from the pulp chamber floor
and taper rapidly to the apex.
Canal is wider buccopalatallyforminga ribbon
like shape.

34. The roots of the maxillary second premolar are
approximately as long as those of the first
premolar, and apical curvature is common,
particularly with large maxillary sinus cavities.
The proximity of this tooth to the sinus can lead to
drainage of a periradicularabscess into the sinus
and exposure of the sinus during apical root
surgery.

35. When two canals are present, the maxillary second
premolar access preparation is nearly identical to
that of the first premolar.
Because this tooth usually has one root, if two
canals are present, they are nearly parallel to each
other and the external outline form must have a
greater buccolingualextension to permit straight-line
access to these canals than with the first premolar
with two roots and diverging canals.

36. If only one canal is present, the buccolingual
extension is less and corresponds to the width
between the buccaland palatal pulp horns
If three canals are present, the external access
outline form is the same triangular shape
illustrated for the maxillary first premolar

37. Bayonet-shaped Canal
It is commonly seen in premolars

40. Mandibularfirst permolar

41. Average time of eruption, 10 to 12 years
average age of calcifcation, 13 to 15 years
average length: 21.6 mm.
root curvature (most common to least common):
straight, distal, buccal.

42. As a group, the mandibularpremolars are diffcult
to treat. They have a high fare-up and failure rate.
A possible explanation may be the extreme
variations in root canal morphology in these teeth.
The root canal system is wider buccolingually
than mesiodistally. Two pulp horns are present:
a large, pointed buccalhorn and a small, rounded
lingual horn.
At the cervical line the root and canal are oval;
this shape tends to become round as the canal
approaches the middle of the root. If two canals
are present, they tend to be round from the pulp
chamber to their foramen.

43. In another anatomic variation, a single, broad root
canal may bifurcate into two separate root canals.
Direct access to the buccalcanal usually is possible,
whereas the lingual canal may be quite diffcultto find.
The lingual canal tends to diverge from the main canal
at a sharp angle.
In addition, the lingual inclination of the crown tends
to direct files buccally,making location of a lingual
canal orifcemore diffcult.
To counter this situation, the clinician may need to
extend the lingual wall of the access cavity farther
lingually; this makes the lingual canal easier to
locate.
The mandibularfirst pre-molar sometimes may have
three roots and three canals .

44. Surgical access to the apex of the mandibular
first premola is often complicated by the
proximity of the mental nerve.
Because of close proximity of root apex to mental
canal and foramen, one may mimic its
radiographic appearance to periapicalpathology.

45. The oval external outline form of the mandibularfirst
premolar typically is wider mesiodistallythan its maxillary
counterpart, making it more oval and less slot shaped
Because of the lingual inclination of the crown, buccal
extension can nearly approach the tip of the buccalcusp
to achieve straight-line access.
Lingual extension barely invades the poorly developed
lingual cusp incline.
Mesiodistallythe access preparation is centered between
the cusp tips. Often the preparation must be modifedto
allow access to the complex root canal anatomy
frequently seen in the apical half of the tooth root.

49. Mandibularsecond
premolar

50. Mandibularsecond premolar
Average time of eruption, 11 to 12 years
average age of calcifcation, 14 to 15 years
average length: 22.3 mm.
root curvature (most common to least common):
straight, distal, buccal.

51. The mandibularsecond premolar is similar to the first
pre-molar, with the following differences:
1.the lingual pulp horn usually is larger
2.the root and root canal are more often oval than
round
3.the pulp chamber is wider buccolingually
4.the separation of the pulp chamber and root canal
normally is distinguishable compared with the more
regular taper in the first premolar.
The canal morphology of the mandibularsecond
premolar is similar to that of the first premolar with
its many variations: two, three, and four canals and
a linguallytipped crown.
Fortunately, these variations are found less often in
the second premolar

53. The access cavity form for the mandibularsecond
premolar varies in at least two ways in its external
anatomy.
First, because the crown typically has a smaller
lingual inclination, less extension up the buccalcusp
incline is required to achieve straight-line access.
Second, the lingual half of the tooth is more fully
developed, and therefore the lingual access
extension typically is halfway up the lingual cusp
incline.

54. The mandibularsecond premolar can have two
lingual cusps, sometimes of equal size. When this
occurs, the access preparation is centered
mesiodistallyon a line connecting the buccal
cusp and the lingual groove between the lingual
cusp tips.
When the mesiolingualcusp is larger than the
distolingualcusp, the lingual extension of the oval
outline form is just distal to the tip of the
mesiolingualcusp

57. Dens Evaginatus
In this condition an anomalous tubercle or cusp
is located on the occlusalsurface , but it may
not be obvious radiographically
Because of occlusalabrasion, this tubercle
wears of fast causing early exposure of
accessory pulp horn that extends into the
tubercle.
This may further result in periradicularpathology
in otherwise caries free teeth even before
completion of the apical root development.
This condition is commonly seen in mandibular
premolar teeth.
and in individuals with Asian ancestry, as well as
Native Americans and Hispanics.

58. There are different treatment measures to prevent
this accidental exposure of the pulp.
One method, before the tubercle fractures, is to
remove the tubercle with a bur and then cap,
followed by a good sealing restoration with
amalgam.

61. References
Cohens’spathway of the pulp , 11 edition ,
chapter 5
Textbook of ENDODONTICS ,THIRD EDITION
,chapter 14
Endodontic principles and practice , edition 4 ,
chapter 13 , appendix A