root canal anatomy and access openings of upper molars

8/11/2019 Root Canal Anatomy and Access Openings of Upper Molars

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Slide 1

Slide 2

Root canal anatomy

and access openings

of upper molars



Slide 3

Classical anatomy:

Upper molars usual ly have

three roots:

Palatal,

Mesio-buccal &

Disto-buccal

Slide 4

•The palatal root is the longest and

round in cross-section.

•The distobuccal root is a little

shorter, but also rounded in cross-

section.

•The mesiobuccal root is more or

less as long as the distobuccal one,

but flatter mesiodistally, meaning it isoval in cross section, wide bucco-

lingual and narrow mesio-distal.



Slide 5

Maxil lary First Molar

EXTERNAL ROOT MORPHOLOGY:

•The maxillary first molar normally

has three roots.

Slide 6

•The mesiobuccal root is broad

buccolingually and has prominent

depressions or flutings on its

mesial and distal surfaces.

•The internal canal morphology is

highly variable, but the majority of

the mesiobuccal roots contain twocanals.



Slide 7

•The distobuccal root is generally

rounded or ovoid in cross section

and usually contains a single canal.

•The palatal root is broader mesio-

distally than bucco-lingually and

ovoid in shape but normally contains

only a single canal.

•Although the palatal root generally

appears straight on radiographs,

there is usually a buccal curvature in

the apical third.

Slide 8



Slide 9

•The overall average length of the

maxillary first molar is 20.5 mm

with an average crown length 0f

7.5 mm and an average root

length of 13 mm.

Slide 10

ROOT NUMBER AND FORM:

•The maxillary first molar root

anatomy is predominantly a three-

rooted form.



Slide 11

•The two rooted form is rarely

reported and may be due to:

- the fusion of the disto-buccal

root to the palatal root,or

- the fusion of the disto-buccal

root to the mesio-buccal root.

Slide 12

•The single root or the conical

form of root anatomy in the first

maxillary molar is very rarely

reported.



Slide 13

CANAL SYSTEM

The internal root canal system

morphology reflects the external

root anatomy.

Slide 14

•The mesiobuccal root of the

maxillary first molar might contain

2 canals (greatest percentage) .

one of them is the main mesio-

buccal canal ( situated buccaly ),

the 2nd is MB2 ( or mesio-lingual)

is positioned palatally to the mainmesio-buccal canal.



Slide 15

•The incidence of two canals in

the mesiobuccal root is about

57.1% and recent reports are

much more percentage.

•The presence of only one MB

canal is 42.9% or less in all

reported studies.

Slide 16



Slide 17

•Less variation was found in the

distobuccal and palatal roots.

They usually have only one canal.

•The distobuccal root had only

one canal in 98.3% of teeth

studied, while

•the palatal root had only onecanal in over 99% of the teeth

studied.

Slide 18

MB root canals:

•The two-canal system of the

mesiobuccal root of the maxillary

first molar has a single apical

foramen in (66.0%)



Slide 19

•The 2 MB canals might beseparate till the apex (34%)

•Rare cases with three canals inthe mesiobuccal root have beendescribed.

Slide 20

•The mesiobuccal root is often

curved distally.

•The degree of curvature varies

from case to case.



Slide 21

•MB2 is the problematic: Of all thecanals in the maxillary first molar,the MB2 can be the most difficult tofind and negotiate in a clinicalsituation.

•Clinicians must be convinced thatMB2 does exist in the mesiobuccalroot of upper molars in 100% of

cases and therefore these teethmust be considered having 4 root

canals.

Slide 22

•The orifice of the“MB2” – moreappropriately named“ mesiopalatal canal” – is located on thegroove that joins thepalatal andmesiobuccal canals ata variable distance fromthe latter.



Slide 23

•Sometimes, however, the probe

cannot enter, because it

encounters the mesial wall of the

pulp chamber where it forms a

very acute angle with the floor

that hampers the visual and

tactile detection of the canalopening.

Slide 24

•The mesial wall of

the pulp chamber has

a dentinal shelf, which

frequently hides the

underlying MB2

orifice.

•Because of this

angle, MB2 can bevery difficult to

negotiate.



Slide 25

•In the first 1-3 mm the root canal

is sharply angled in a mesial

direction, and

•this is the reason why sometimes

the tip of the file doesn’t progress

apically more than a few

millimeters and stops against themesial wall.

Slide 26

•This can be done easily, safelyand efficiently with ultrasonics andthe specific tips, like CPR andProUltra

• Use multiple obliquely angledradiographs (disto-mesialinclination in particular) bothpreoperatively andintraoperatively: the broader theroot, the greater the likelihood of a second canal system.



Slide 27

•The two canals do not always

have separate foramina; more

often, they join together in a

single foramen.

•Failure to detect and treat the

second MB2 canal system willresult in a decreased long-term

prognosis.

Slide 28

A transverse section at the level

of the cervical zone of the upper

first molar reveals that the pulp

chamber floor takes the form of a

quadrilateral with four unequal

sides.



Slide 29

Slide 30

•The MB canal is under the MBcusp tip

•The palatal canal is always under the MP cusp tip

•The DB canal has no relation toits cusp, as seen in the next

picture.



Slide 31

Slide 32

Access preparation

•Preparation of the access cavity

begins with a round, diamond bur

mounted on a high speed

handpiece and applied at the

level of the central fossa.

•It is inclined toward the pulp horn

that radiographically seems

widest, generally the palatal one.



Slide 33

Slide 34

•With the low-speed,

long-shafted round

bur, the dentin

undercuts are

removed, proceeding

internally to

externally.



Slide 35

•Finally, the self-

guiding diamond bur

on high speed is

used for the finishing

and flaring.

Slide 36

Maxillary Second Molar

EXTERNAL ROOT MORPHOLOGY

•The maxillary second molar normally

has three roots.



Slide 37

•The relative shape of each of theroots is similar to the maxillary firstmolar, but:

-the roots tend to be closer together and

- there is a higher tendency towardfusion of two or three roots.

- There is also usually more of adistal inclination to the root or roots

of this tooth compared to themaxillary first molar.

- the crown is smaller in size

Slide 38

•The overall average length of the

maxillary second molar is 19 mm

with an average crown length of 7

mm and an average root length of

12 mm.



Slide 39

ROOT NUMBER AND FORM

•The majority of maxillary second

molars (88,6%) in the anatomical

studies were found to be three

rooted. Lower incidence than first

molar.

•The closer proximity of the roots

results in a higher incidence of root

fusion (25.8%), and C-shaped

canals (4.9%) when compared to the

maxillary first molar.

Slide 40

CANAL SYSTEM

•There was a single apical

foramen found in the mesiobuccal

root over 68% of the time.

•The distobuccal and palatal roots

exhibited a single canal over 99%

•Sometimes the three roots fuse

in one root.



Slide 41

•It may have only two canals, one

buccal and one palatal in a single

root, or

•two canals in two separate

roots;

Slide 42

•it may have a single, wide canal

that extends almost directly from

the floor to the apex.



Slide 43

•In comparison with the upper first

molar, the pulp chamber floor of

the upper second molar is flatter

mesiodistally, and the

distobuccal canal is found

quite palatally displaced.

Slide 44

UPPER THIRD MOLAR

•Loss of the first and second

molars is often the reason for

considering the third molar a

strategic abutment.

•In some cases, the third molar

has only one canal.



Slide 45

•In other cases, it has two, but in

most there are three and,

sometimes, four.

•The access cavity should be

made according to the same rules

prescribed for the other molars.

Slide 46

Maxillary Molar Teeth

ERRORS in Cavity

Preparation



Slide 47

A. UNDEREXTENDED

preparation.

•Pulp horns are exposed

but the entire roof of the

pulp chamber was not

removed.“White” color

dentin of the roof is a

clue to underextension.Instrument control is lost.

Slide 48

B. OVEREXTENDED

preparation

undermining enamel

walls.

•The crown is badly

gouged owing to

failure to observe pulp

recession in the

radiograph.



Slide 49

C. PERFORATION intofurca using a surgical-length bur and failing torealize that the narrowpulp chamber had beenpassed.

•Operator error in failureto compare the length of the bur to the depth of

the pulp canal floor.•Length should bemarked on the bur shankwith Dycal.

Slide 50

D. LEDGE FORMATION

caused by using a large

straight instrument in a

curved canal.



Slide 51

E. PERFORATION of

a palatal root which

is curved buccally at

its apex commonly

caused by assuming

the canal to be

straight and failing to

explore and enlargethe canal with a fine

curved instrument.

Slide 52

Strategies to search for MB2

a) First of all, strongly believe

that MB2 is always present!

b) Use of magnification, starting

from loops and magnification

glasses (2,5x – 4x) up to the

operating microscope.



Slide 53

c) Start looking for MB2 only after

MB1 is completely cleaned and

shaped and, in theory, is ready for

obturation.

d) Use a piezo-electric ultrasonic

unit along with specially designed

tips (CPR, ProUltra) to remove

the dentinal shelf hiding the

underlying orifice.

Slide 54

e) Use of 1% solution of MethyleneBlue dye, to road map the anatomyby penetrating into orifices.

f)Flood the pulp chamber with awarm 5% solution of sodiumhyplochlorite to conduct the“champagne” or “bubble” test.

The clinician can frequently visualize

bubbles emanating from organictissue, which is being digested in theextra canal, and rising towards theocclusal table.



Slide 55

g) Irrigate with 17% EDTA to

remove the smear layer, then

•with pure alcohol and then

•air-dry with a Stropko irrigator

fitted with a 27-gauge notched

endodontic irrigating needle.

Slide 56

h) Use multiple obliquely angled

radiographs (disto-mesial

inclination in particular) both

preoperatively and

intraoperatively: the broader the

root, the greater the likelihood of

a second canal system.i)Know the endodontic anatomy.

root canal anatomy and access openings of upper molars

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