Root apex and working length determination

CONTENTS
 ROOT DEVELOPMENT
 ANATOMY OF ROOT APEX
o APICAL FORAMEN
o APICAL CONSTRICTION
o CDJ
o LATERAL AND ACCESSORY CANALS
o CANAL CURVATURE
o TYPES OF ROOT APEX
 AGE CHANGES
 CLINICAL SIGNIFICANCE OF ROOT APEX
o WORKING LENGTH
o WORKING WIDTH
o ENDODONTIC SURGERY
o PROCEDURAL ERRORS
 CONCLUSION

INTRODUCTION
 Morphologically-most complex region
Therapeutically-most challenging zone
Prognostically- most important part
Radiographically-most obscure and
unclear area

 Thorough comprehension of apical region of tooth
is essential to determine the working length and
working width to the most accurate position
biologically .
 Scrupulous understanding and knowledge of the
root apex is also a requisite to perform a
successful endodontic surgical procedure.

 A detailed knowledge of the apical part of the
root canal system is vital as it is a common
area for procedural errors during
instrumentation

HETWIGS EPITHELIAL
ROOT SHEATH
Consists of outer
and inner enamel
epithelium.
Molds the shape
of roots and
initiates radicular
dentin formation

 Cells of inner epithelia induce the differentiation of
radicular cells into odontoblasts.
 HERS loses its continuity when first layer of
dentin is laid down
Enamel
Ameloblasts
Stratum
Intermedium
DEJ
Future Cemento
enamel Junction
Epithelial rests of
Malassez
Disintegration of
Hertwig’s epithelial
Root Sheath
Coronal dentin
Odontoblasts
Pulp
Root Dentin
Inner enamel
epithelium

 Epithelium is moved away from surface of dentin
–CT comes in contact with dentin and
differentiates into cementoblasts
Odontoblast
Predentin
Root dentin
Dentino cemental
Junction
Pulp
Cementoid
Cementum
Cementoblast
Cementocyte
Dental sac
Dental sac cell
Becoming a
Cementoblast
Formation of
Periodontal ligament
Epithelial rests
Of Malassez
Developing bone

 In multirooted teeth-root sheath forms epithelial
diaphragm
 It bends at future CEJ into a horizontal plane

The classic concept of apical root
anatomy is that there exists three
anatomic and histologic landmarks
the apical
constriction
the cemento-
dentinal junction
and the apical
foramen

ACCORDING
TOKUTTLER
Root canal tapering from the canal
orifices to the AC which is generally
0.5–1.5 mm inside the AF..
the diameter of the AF in the age
range of
18–25 was 502 μm and
over 55 years of age was 681 μm,
demonstrating its growth with age.

The shape
of the
space
between
the major
and minor
diameters
has
variously
been
described
as funnel-
shaped,
hyperbolic
or 'morning
glory'.
The mean
distance between
the major and
minor diameters
0.5 mm in a
young person
and 0.67 mm in
an older
individual.
The increased
length in older
individuals is due
to the increased
buildup of
cementum

APICAL FORAMEN
'circumference or
rounded edge, like a
funnel or crater, that
differentiates the
termination of the
cemental canal from the
exterior surface of the
root'.
Inadequate knowledge
and mismanagement of
apical foramen may
affect long and short
term success of RCT
Location and shape of
fully formed apical
foramen vary in each
tooth and in same tooth
at different periods of life
May change due to
functional influences-
occlusal pressure,mesial
drift

GREEN(1955 1956 1960)-
Major apical foramen are situated
directly at the apex more
frequently in maxillary centrals,
laterals, cuspids, first premolars
and mandibular second
premolars
In the maxillary molars and all
the mandibular teeth with the
exception of the 2nd PM, the
main apical foramina coincide
with the apexes less
frequently.

(A)Major apical foramen (apical opening) with
protruding instruments
(B) root apex.

Briseno Marroquin et
al. investigated the
apical anatomy of 523
maxillary and 574
mandibular molars
from an Egyptian
population
The most common
physiological foramen
shape was oval
(70%);

Size of main apical foramina
Teeth Mean values (u)
Maxillary incisors 289.4
Mandibular incisors 262.5
Maxillary premolars 210.0
Mandibular premolars 268.2
Maxillary molars
Palatal 298.0
Mesiobuccal 235.05
Distobuccal 232.20
Mandibular molar
Mesial 257.5
Distal 392.0
*Results published previously in: Morfis A, Sylaras SN, Georgopoulou M,
Kernani M, Prountzos F. Study of the apices of human permanent teeth
with the use of a scanning electron microscope. Oral Surg Oral Med
Oral Pathol Oral Radiol Endod 1994: 77(2):172–176.

Apical foramen is not
always the most
constricted part of
canal
Ideally the root filling
should stop at this
constriction as it would
serve as an apical dentin
matrix-
APICAL
CONSTRICTION

Mean perpendicular distance from
the root apex to the apical
constriction
Teeth Mesiodistal (mm) Labiolingual (mm)
Vertical (mm)
Central incisor 0.370 0.428
0.863
Lateral incisor 0.307 0.369
0.825
Canine 0.313 0.375
1.010
*

DUMMER
CLASSIFICATION
1TYPICAL SINGLE
CONSTRICTION
2. TAPERING CONSTRICTION
WITH THE NARROWEST
PORTION
NEAR THE ACTUAL APEX
3. SEVERAL CONSTRICTIONS
4. CONSTRICTION FOLLOWED
BY A NARROW, PARALLEL
CANAL
5. COMPLETE BLOCKAGE OF
THE APICAL CANAL BY
SECONDARY
DENTIN

Radiograph (A) and histologic
section (B) of ideal
apical constriction on tooth #7.
Radiograph (A) and histologic section
(B) of slight
apical constriction

(B) of palatal root of tooth #15 with no
apical
constriction

(B) of mesial root of tooth #19 with
apical
foramen well short of radiographic
apex.

Radiograph (A) and histologic section (B)
of
mesial root of tooth #31 with inflammatory
root resorption

Natural stop during root canal
preparation and filling
Precautions should be taken to maintain size of
constriction and patency of foramen
-Should not be enlarged nor blocked
-working length measured correctly
-canal patency maintained through
recapitulation
- adequate irrigation to prevent
acccumulation of dentin

DENTINAL
JUNCTION
The CDJ is the
point in the canal
where cementum
meets dentine.
Histological
landmark, cannot
be located
clinically or radio
graphically

ACCORDING TO
KUTTLER(1958)
Root canal is divided into a long
conical dentinal portion and a short
funnel shaped cemental portion
Cemental portion is in form of
inverted cone with its narrowest
diameter at or near CDJ and base
at apical foramen

Ponce and Vilar Fernandez determined the location and
diameter of the CDJ
Extension of cementum from the AF into the root
canal differed considerably on opposite canal
walls.
Reached the same level on all canal walls only 5%
of the time. The greatest extension occurred on the
concave side of the canal curvature.
This variability reconfirmed that the CDJ and AC
are generally not the same area and that the
CDJ should be considered just a point at which
two histologic tissues meet within the root canal.
The diameter of the canal at the CDJ was
highly irregular and was determined to be
353 μm for maxillary centrals, 292 μm for
lateral incisors and 298 μm for canines

 Does not always
coincide with minor
diameter
(Langeland et
al,1998)
 Located 0.5-3.0 mm
short of the
anatomic apex
(Tamse A,
KaffeI, Fishel
D, 1980)

 Theoretically, the CDJ is the appropriate
apical limit for root canal treatment as at
this point the area of contact between the
periradicular tissues and root canal filling
material is likely to be minimal and the
wound smallest
(Palmer et al. 1971, Seltzer 1988, Katz
et al. 1991, Ricucci & Langeland 1998)

 The term ‘theoretically’ is applied here because
the CDJ is a histological site and it can only be
detected in extracted teeth following sectioning, in
the clinical situation it is impossible to identify its
position.
 In addition, the CDJ is not a constant or
consistent feature, for example, the extension of
the cementum into the root canal can vary (Ponce &
Fernandez 2003).
 Therefore, it cannot be an ideal landmark to use
clinically as the end-point for root canal
preparation and filling.

ACCESSORY AND
LATERAL
CANALS
Lateral canal is located at
right angles to main root
canal
Accessory canal branches
off from the main root
canal in the apical region
Furcation canal seen at
furcation

Formed when the root
sheath disintergrates when
dentin is elaborated or lack
of dentin formation around
a blood vessel which is
present in periradicular
connective tissue

Contains fibrous
tissue-fibroblasts,
collagen fibres ,
nerves,
macrophages
(resemble CT of
PDL rather than
pulp)
Lateral canals
are more
common in
bifurcation and
trifurcation
region of molars

According to HESS et
al (1963)
accesory canals have
a mean diameter of 6-
60 µm
Accessory canals
form apical deltas
in the root apex
In distal root of mandibular
molars and palatal of
maxillary molars –these
canals fan out towards the
apex in a canoe –shaped
arrangement

These canals are
avenues for interchange
of metabolic and
breakdown products
between pulp and perio
dontal tissue

if present in the floor of
pulp chamber these
canals transmit toxins
and irritants from pulp
cavity and establish a
lesion in furcation which
may appear
radiograpically as
periodontal disease

They are usually not detected in intraoral
radiographs
They may become noticeable
subsequent to the necrotization of the
main canal
Thickening of the PDL or development of
a frank lesion in the lateral wall of the
root
Also become apparent in the post –obturation x-ray where
radio-opaque material is seen extending to surface of root

Presence of these
canals emphasize the
need for employing
effective irrigation
solution and
technique and also
three dimensional
filling of root canal

Also when the pulp is
extirpated from a vital
tooth ,pulp stump
may remain in these
canals –causing post-
pulpectomy pain and
also pain felt when
sealer is pushed into
these canals

These canals may harbour
micro organisms and
continue to irritate periapex
.
Lesion may grow despite
radiographic evidence of
proper filling of principal
canal.
These cases require
periapical surgery

Presence of multiple accessory and lateral canals is the rule
and not the exception as evident from various studies
The number of accessory canals does not appear to be
significant in the successs or failure of RCT teeth
According to
HESS(1983)
following endodontic therapy in teeth with
vital pulps the lateral and accessory canals
become obliterated by the deposition of
cementum with the passage of time
In non-vital teeth, inflammatory tissue will
get resorbed and replaced with uninflammed
connective tissue.

Although the
incidence of
occurrence of these
canals is high – the
percentage of failures
due to unfilled canals
is small in clinical
practice
This is because of the
biological hard tissue
closure(cementum)
subsequent to the
elimination of chronic
inflammation and
irritants from main
canal

CANAL CURVATURE
Apical third of roots are complex
also in curvature
Usually teeth show a distal
curvature in apical third
A buccal or lingual curvature may
not be discernible in radiograph

When
tooth
erupts
into oral
cavity its
apex is
not
complete
ly
formed .
as the tooth
becomes
functional it is
subjected to
biting
stresses
which may
move the
tooth mesially
this slow
bodily
movement
of the
incompletel
y formed
tooth is the
cause of
curvatures
in the
apical third
of the root
Curvature
formation

Clinical management
Preflaring of the coronal
part of canal facilitates the
proper instrumentation of
apical curvature
Prebending of files
during instrumentation
improves the
negotiation of the
curvature
Failure to do so
results in ledging
,ripping,iatrogenic
canal formation or
perforation

TYPE OF ROOT APEX
THIN PINCHED
APEX
proper care required
during instumentation
Over enlargement may
lead to perforation

BULBOUS APEX
usually due to
hypercementosis
proper care required during
length determination
Apical constriction is
significantly shorter from
radiographic apex

RESORBED APEX
caused due to advanced
inflammation at the periapex
resorption of cementum and
dentin and widening of apical
foramen
WL determination ,preparation
and condensation of guttapercha
is difficult-
Preparation should stop 1-2mm
short of radiographic apex

BLUNDERBUSS APEX
newly erupted tooth showing
an incompletely formed root
having a wide canal and an
open apexthe pulp may get necrosed
due to carie or trauma and
may require root canal
therapystandard instrumentation
and obturation techniques
are not favorable

Walls of canal are thin and fragile
Also lacks apical constriction
Treatment depends on
the condition of pulp-
if vital –apexogenesis is done
if nonvital -apexification or peri-apical
surgery required

HISTOLOGY OF APICAL
DENTIN AND PULP

APICAL PULP TISSUE
Differs structurally from coronal pulp tissue
Apical pulp – More fibrous & contain fewer cells
This fibrous structure appears to act as a barrier against the apical
progression of pulp inflammation.
It also supports the blood vessels and nerves which enter the pulp.

APICAL DENTIN
In apical region, odontoblasts are absent or flattened or
cuboidal
Dentin is more amorphous & irregular - sclerotic dentin
(Azaz et al 1977, Johansen 1971)
Sclerotic apical dentin is less permeable than coronal
dentin

AGE CHANGES
Rule of thumb-root formation completed
3 years after eruption
THOMAS et al
apex may not mature until the age of 12
years or later in maxillary first molars
also palatal roots may not exhibit
maturity even by 15 years of age

Root length
Apical closure
completion
 Mand central incisor 8 ¼ 8 ½ 10
9 ½
 Mand lateral incisor 10 9 ½ 11 ½
10 ½
 Mand canine 12 ½ 11 18
14
 Mand first premolar 13 12 16 ½
15
 Mand second premolar 14 13 17
½ 16 ¼
 Mand first molar
mesial root 7 7 10

REMODELLING/DEPOSITION
OF CEMENTUM AT THE APEX
IS AN AGING PROCESS-
occurs to
compensate for
attrited enamel
or physiological
mesial migration of
tooth

Thus increase in overall
distance from apex to
apical constriction
Also a decrease in
canal width

ROOT APEX AND ITS CLINICAL
SIGNIFICATION

• WORKING LENGTH
• WORKING WIDTH
• PROCEDURAL
ERRORS
• ENDODONTIC
SURGERY

WORKING LENGTH
One of the main concerns in root canal treatment
is to determine
 how far instruments should be advanced within
the root canal
 and at what point the preparation and filling
should terminate (Katz et al. 1991).
Cleaning shaping and obturation cannot be
accomplished accurately unless wl is determined
precisely

When correct working
length is not
maintained

 Working short results in
 incomplete cleaning
 allows pulp tissue and necrotic debris to remain in the
canal
 persistent discomfort as the pulpal remnants are left
behind
 Under filling
 incomplete apical seal
 apical leakage which supports the existence of viable
bacteria and contributes to periradicular lesion and

 Failure to accurately determine and maintain the
working length may result in
 Perforation through the apical constriction
 destroys the delicate apical region of the canal and
can cause potential damage to the periapical
tissues
 Increased incidence of post operative pain
 Delayed healing

CDJ MINOR
DIAMETER
Apical end of working
length

 CDJ
not clinically identifiable
not constant and consistent
Therefore not used as the apical stop in clinical
practice

 According to Kutler, the narrowest
diameter of the canal is definitely not
at the site of exiting of the canal from
the tooth but usually occurs within the
dentin, just prior to the initial layers of
cementum.
 He referred this position as the minor
diameter.
 This is the site that is preferred to
terminate canal preparation and build
up the apical dentin matrix.

 In clinical practice, the minor apical foramen is a
more consistent anatomical feature that can be
regarded as being the narrowest portion of the
canal system
 and thus the preferred landmark for the apical
end-point for root canal treatment.

Various methods
Conventional
methods
• -Radiographic
method
• -Digital tactile
sense
• -Apical
periodontal
sensitivity
• -Paper point
method
• Radiographic
grid
Advanced
method
• -Electronic
method
• -Direct digital
radiography
• Xeroradiography
• Subtraction
radiography

Grossman’s method
 Instrument placed in root canal extending till
apical constriction using tactile sense
 Radiograph is taken
 Measure radiographic lengths of tooth &
instrument & calculate actual length of tooth
using the formula
 Actual length of tooth = Actual length of instrument × length of
tooth
Radigraphic length of
instrument

Ingle’s method
 The tooth is measured on a good preoperative
radiograph using the long cone technique.

 Tentative working length.
 As a safety factor, allowing for image distortion or
magnification,
 subtract at least 1 mm from the initial measurement
 The instrument is set with a stop at this length.

 Final working length-
 The instrument is inserted to this length and a
radiograph is taken.
 On Radiograph-.measure diff b/w end of instrument
and end of root
 This is added to the tentative working length
 From this measurement 1mm is subtracted as
adjusment for apical termination

Weine recommendation
1mm from apex -no bone or root resorption
1.5mm from apex -only bone resorption
2mm from apex -both bone and root resorption

Kuttlers method
 Acc to KUTTLER narrowest daimeter-
apical constriction
Avg distance bw minor and major diameter
young-0.524mm
older-0.659mm
• If file reaches major diameter exactly-
subtract 0.5mm from length in young
0.67mm from length in old

Apical periodontal sensitivity
 Based on the patient’s response to pain when
reaching the periradicular tissues
 not an ideal method

Paper Point Measurement
• uses conventional absorbent paper points
 and it is based on the assumption that when the
contents of the root canal system are removed,
the canal should be dry, while the environment
outside the root canal is living and hydrated.

 According to Rosenberg-
 if a paper point is placed into a dried canal short of
the apical foramen, it should be retrieved dry.
 If taken past the exit of the canal, it will be retrieved
with fluid.

Digital tactile sense
 Clinician may detect an increase in resistance
as the file approaches the apical 2 to 3 mm.
 This detection is by tactile sense. In this region,
the canal frequently constricts (minor diameter)
before exiting the root.
 Seidberg et al. reported an accuracy of just 64%
using digital tactile sense.

Radiographic grid
 Imposing a mm grid on the radiograph to
overcome need for calculation

A new level of accuracy in length
determination over radiographs has been
achieved with the electronic apex locator
(EAL)
The EAL is free of the problems that visual
interpretation of two-dimensional radiographs
present
Unfortunately, the EAL is not 100% accurate

ADVANTAGES
 Decreases patient exposure
 Used when radiographs are difficult to read
 Used to detect perforations
 Easy and fast
 Can be used in pregnant patients, children
,patients with gag reflex

 Detection of perforations
 Radiographic detection often hinders the
existance of the perforation, particularly when it
occurs bucco-lingually
 Using apex locator a sudden rise in reading
indicates a perforation

Particularly useful when the apical portion of the canal system is
obscured by certain anatomic structures:
Impacted teeth
Tori
Zygomatic arch
Excessive bone density
Overlapping roots
Shallow palatal vault
To det:W/L as an important adjunct to radiography
(↓treatment time &radiation)

DISADVANTAGES
 Not 100% accurate
 Not useful in immature teeth
 May show inaccurate readings
 cannot be used in patients with cardiac
pacemakers

HISTORY
CUSTER (1918) - First to investigate an electronic method to determine
working length
SUZUKI (1942) - Electrical resistance between the periodontal ligament
and
oral mucous membrane - 6.5kΩ
SUNADA (1962) - Constructed the first apex locator, resistance type.
INOUE (70’s – 80’s) – Used audiometric component
( Low Frequency audible sounds )
For eg – Sono explorer
HASEGAWA (1986) - Impedance type apex locator
YAMASHITA (1990) - Frequency type apex locators, Difference method
For Eg - Endex
KOBAYASHI (1991) - Frequency type apex locators, Ratio Method
For Eg- Root ZX

HOW APEX LOCATORS
FUNCTION
 use the human body to complete an electrical circuit.
 One side of the circuitry is connected to an endo
instrument & the other end to the patients body--
patients lip or by an electrode held in the patients
hand.

Their functionality is based on the fact that the
electrical conductivity of the tissues surrounding
the apex of the root is greater than the
conductivity inside the root canal system
provided the canal is either dry or filled with a

CLASSIFICATION
The classification of apex locators
currently in use is a modification of the
classification presented by McDonald.
This classification is based on the
type of
current flow and the opposition to the
current flow,
As well as the number of frequencies

CLASSIFICATION
1. FIRST GENERATION APEX
LOCATORS
( Resistance apex locators.)
• It measures the opposition to the flow of
direct current or resistance.
• When the tip of the reamer reaches the
apex in the canal ,the resistance value is
6.5 k
• Eg sono-explorer

Advantages
Disadvantages
easily operated dry field required
digital read out calibration required
audible indication patient sensitivity
may incorporate pulp tester lip clip with good contact
required

 To eliminate the disadvantages of DC current
Suchde & Talim (1977) proposed using AC
current to measure the resistance.
 The advantages of AC current are that it causes
less damage to the tissue and improves
functionality in ‘wet’ conditions as the resistivity of
the electrolytes experience better stability
(Suchde & Talim 1977, Foster & Schwan 1989).

SECOND GENERATION APEX LOCATORS
(Impedance apex locators )
 It measures opposition to the flow of alternating
current or impedance. Employed Single frequency
 It uses the electronic mechanism that the highest
impedance is at the apical constricture,-

Advantages Disadvantages
May operate in fluid difficult to
operate
no patient sensitivity no digital read
out
no lip clip required inaccurate in
open apices

 The Apex Finder (Sybron Endo/Analytic;
Orange, Calif.)–
visual digital LED indicator
- self calibrating
Endo Analyzer (Analytic/Endo; Orange, Calif.)
combined apex locator and pulp
tester.

 Digipex- Mada Equipment Co., Carlstadt, N.J.)
- visual LED digital indicator
-audible indicator.
-requires calibration.
 Digipex2 :
- combination of apex locator and pulp tester
 Exact-A-Pex:- (Ellman International, Hewlett ,N.Y.)
- LED bar graph display
- audio indicator

 Foramatron IV :- Parkell Dental,
Farmingdale, N.Y.)
-flashing LED light
- digital LED display
- does not require calibration
 The Pio apex locator
- analog meter display
- audio indicator .
- adjusting knob for calibration

THIRD GENERATION APEX LOCATORS
(Frequency – dependent apex locators)
By Kobayashi and Suda 1990
- measures the impedance difference between
two frequencies or ratio of two electrical
impedances
-As the file moves towards the apex,the
difference becomes greater
-shows greatest value at the apical
constricture,allowing for the measurement of that
location

Advantage
Disadvantages
Works in presence of fluid requires
calibration
Easy to operate requires lip
clip
Audible indication

 Endex:-original 3rd
gen:apex locator --
Yamashita et al(1990)
• Measures the difference in impedances of
alternating currents at frequency of 5 and 1kHz

Neosono ultimo Ez:
• Multiple frequences
• Wet or dry canals
• Mounted with root
canal graphic
showing file position
and audible signals

Root ZX
 dual frequency
 comparative impedance
principle-described by
Kobayashi (1991)

Apex locators with other functions:
(TRI AUTO ZX)
 cordless electric endodontic hand piece with
a built in Root ZX apex locator. The hand
piece uses nickel titanium rotary instruments
that rotates at 280 50rpm.

FOURTH GENERATION APEX
LOCATORS
 Uses multiple frequencies
 Breaks impedance into its primary components –
resistance and capacitance and measures them
independently during use
Bingo Elements diagnostic
unit

FIFTH GENERATION APEX
LOCATORS
 based on the multi-frequency closed circuit
human body's oral cavity.
 ROOT-PI (III) Denjoy dental, exclusive
manufacturer in China

 The most important objective of root canal
therapy is to minimize the number of
microorganisms and pathologic debris in root
canal systems to prevent or treat apical
periodontitis.
 Thorough instrumentation of the apical region has
long been considered to be an essential
component in the cleaning and shaping process.

 It was discussed as a critical step as early as
1931 by Groove
 Simon later recognized the apical area as the
critical zone for instrumentation.
 Other authors also concluded that the last few
millimeters that approach the apical foramen are
critical in the instrumentation process.

Horizontal dimension of RC system more complicated than
vertical dimension
Difficult to investigate horizontal dimension as it varies greatly
at each vertical level of the canal
In principle, however, preparing each canal to a specific
apical diameter as per its initial apical size may better equip
the clinician to provide a more predictable canal preparation.

SHAPE
Kuttler (1955) & Mizutani et al (1992)
oval,
long oval,
ribbon shaped or
round
Wu et al (2000) –
25% of apical construction had long oval shape
Mauger et al (1998)
51 – 78% did not have round apical constriction
Apical construction is not uniformly round  oval
or irregular

size of the apical preparation:
 determine the pre-operative canal diameter by
passing consecutively larger instruments to the
WL until one binds
 The first size that binds at the working
length is called the initial apical file (IAF)

Factors affecting the determination of
minimal initial apical width
Canal
shape.
Curvatur
e
Length
ContentCanaal wall
irregularities
Taper
Instrume
nt used

Preflaring
Studies have reported that initial flaring before
determining the apical size may give a more accurate
measurement of the apex
Tan and Messer reported that the apical diameter proved
to be at least one file size bigger once preflaring was
done.
Tan BT, Messer HH. The effect of
instrument type and preflaring on
apical file size determination. Int
Endod J 2002;35:752– 8.

 Contreras et al. reported the apical size
to be two file sizes bigger after preflaring
with Gates-Glidden drills.
Pecora et al. reported that the
instrument used for preflaring played
a major role in determining the
anatomical diameter at the working
length (WL)
Contreras MA, Zinman EH, Kaplan SK. Comparison of the first file that
fits at the apex, before and after early flaring. J Endod 2001;27:113–
6.
Pecora JD, Capelli A, Guerisoli DM, Spano JC, Estrela C. Influence
of cervical preflaring on apical file size determination. Int Endod J
2005

 The classic test for determining correct width
finding of clean, white dentin shavings on the flutes
of the reamers and files.
 But, does not necessarily indicate thorough
removal of tissue, debris, and affected dentin

 Many canals are oval or ribbon shaped in cross
section. Clean, white dentin shavings are
attainable from walls close to each other, but the
far walls may be completely untouched while this
sign is obtained

 According to Weine,
 The master apical file size is suggested to be the
three ISO file sizes larger than the initial binding file.
 The file three sizes larger than the first file that binds
is called the master apical file (MAF)

Glickman and
■
Tooth Grossman Tronstad Dumsha Weine
Maxillary
Centrals 80-90 70-90 35-60 3 sizes
Laterals 70-80 60-80 25-40 3 sizes
Canines 50-60 50-70 30-50 3 sizes
First premolars 30-40 35-90 25-40 3 sizes
Second premolars 50-55 35-90 25-40 3 sizes
Molars 30-55-50 3 sizes
MB/DB 35-60 25-40 3 sizes
P 80-100 25-50 3 sizes
Mandibular
Centrals 40-50 35-70 25-40 3 sizes
Laterals 40-50 35-70 25-40 3 sizes
Canines 50-55 50-70 30-50 3 sizes
First premolars 30-40 35-70 30-50 3 sizes
Second premolars 50-55 35-70 30-50 3 sizes
Molars 30-55-50 3 sizes
MB ML 35-45 25-40 3 sizes
D 40-80 25-50 3 sizes

 Studies suggested that root canal have not
been thoroughly cleaned even after being
enlarged 3 size greater than their original
diameters.
Jou YT, Karabucak B, Levin J, Liu D.
Endodontic working width: current concepts
and techniques. Dent Clin North Am
2004;48:323–35.
 – Histologic studies showing canals that were
instrumented to three sizes larger still were
not thoroughly cleaned
Walton 1976

 Earlier research has shown that canals needed to
be enlarged to at least #35 file for adequate
irrigation to reach the apical third
Salzgeber RM, Brilliant JD. An in vivo evaluation
of the penetration of an irrigating solution in root
canals. J Endod 1977
 Ram et al had concluded that canals need to be
enlarged to a #40 file size so that maximum
irrigation is in contact with the apical debris.
Ram Z. Effectiveness of root canal irrigation.
Oral Surg 1977.

 Larger instrumentation sizes not only allow
proper irrigation but also significantly
decrease remaining bacteria in the canal
system.
 Orstavik et al. (IEJ 1991) demonstrated that
instrumentation with a #45 file decreased the bacterial
growth by 10-fold.
 Sjogren et al.( IEJ 1991) reported that a #40 file
decreased bacteria better than smaller sized files.
 Dalton et al.( JOE 1998) also showed with increasing
file size, there was an increasing reduction of
bacteria.

 The study of Yared and Dagher who reported that a
#25 file was as efficient as a #40 file for reducing
residual microorganisms.
 Yared GM, Dagher FE. Influence of apical enlargement on
bacterial infection during treatment of apical periodontitis. J Endod
1994
 Buchanan (2001)has advocated minimal apical
preparation (e.g. #20 or #25) based on his clinical
opinions.
He proposed that enlarging the canal size would
cause apical transportation or zips.
These techniques focus more on minimal apical

 A 4-6 year clinical study on endodontic outcomes
favored smaller preparation sizes with tapered
shapes to larger shapes.
 90% and 80% success rate respectively
 Treatment outcomes in Endodontics: the Toronto
Study. Phase I and II. Friedman et al Journal of
Endodontics 2004; 30:9

 Baumgartner in his study concluded that an
apical preparation size 20 would be inferior to
size 30 and 40 regarding canal debridement but a
larger taper (0.10) may potentially compensate
for smaller sizes.
 Baumgartner et al. influence of instrument size on
root canal debridement Journal of Endodontics
2004;30:110

 Mickel et al based on microbiological assays
found that apical preparation to size 30 is
required to effectively clean root canals
 Mickel AK, Chogle S, Liddle J. The role of apical
size determination and enlargement in the reduction
of intracanal bacteria. Journal of Endodontics 2007;
33:21

methods to locate the root apex-
 radiographic method
 methylene blue dye
- preferentially
stains PDL
 visual method-
root structure has a
yellowish colour
root texture is smooth
and hard /bone is granular,
porous

Extent of apical resection
 3mm apical resection –to eliminate most of lateral
canals and apical deltas

Bevel angle
 Earlier 45 degree bevel
angle placed to bring apical
foramen labially
 At present 0-10 degree
benefit of microsurgical
procedures

Advantages
 minimizes removal
of excess buccal
cortical plate
 exposes fewer
dentinal tubules thus
preventing excess
leakage and
contamination

Case report 1
A, A clinical photograph of a 34-year-old man with swelling
in the buccal furcation
area of his mandibular right first molar, tooth #30. He gives
a history of previous root canal treatment with silver cones
that required retreatment
. B, A preoperative radiograph.

C and D, After root resection, inspection of the root and root tip is important.
Note the accessory canals associated with the root tip.
E, A clinical photograph taken after root end resection and filling. Note the
perpendicular resection as well as
the pathologic defect. F, A radiograph of the completed root end filling

. G and H, A 1-year recall
photograph and radiograph
demonstrate resolution of the
lesion and
osseous regeneration.

Case report 2
A, Preoperative clinical photograph of a draining sinus tract opposite
the maxillary
right second premolar, tooth #4, 6 months after retreatment. The
adjacent teeth were responsive to
pulp testing with C02 . B, Preoperative radiograph demonstrates a
periradicular radiolucent area.

C, A clinical photograph of the
resected root end
D,
A
postoperativ
e radiograph

PROCEDURAL ERRORS
SEEN AT THE ROOT APEX

 . Procedural accidents in endodontics
are those unfortunate occurrences that
happen during treatment, some due to
inattention to detail, and others totally
unpredictable

LEDGING
 Any deviation from the original canal curvature
results in the formation of a ledge.
CAUSES
 Inadequate access cavity preparation
 False estimation of pulp space direction
 Failure to pre-curve SS instruments
 Failure to use instruments in a sequential
manner
 Attempt to retrieve separated instruments
 Attempt to prepare calcified canals

 Recognition:
A ledge is suspected when the root canal
instrument can no longer be inserted into the
canal to full working length
 Correction:
 Pre-curved No. 10 file is used to bypass the
defect and to explore the canal to the apex
 Use a lubricant, irrigate frequently to removal
dentin chip, maintain a curve on the file tip, and
using short file strokes press the instrument
against the canal wall where the ledge is
located.
 Prevention:
Pre-curving instruments and not “forcing” them is

APICAL
TRANSPORTATION
 Moving the position of the position of the canal’s
physiologic terminus to a new iatrogenic location
on the external root surface is called
transportation of the foramen
 . Correction:
Mineral trioxide aggregate is barrier of choice.
In severe cases where barrier technique
cant be created corrective surgery is required.
 Prevention:
Don’t use large instrument initially.
Correct determination of working length

PERFORATION
 An artificial opening in a tooth or its root , created
by boring, piercing ,or cutting, which results in a
communication between the pulp space and the
periodontal tissues
 Incidence 3-10%

Level: More apical the perforation, more
favorable the prognosis.
Size: Perforation size greatly affect the
clinician’s ability to establish a hermetic seal.
Mathematically described as - r2 (r =
radius).
Therefore doubling the perforation size with
any bur or instrument increases the surface area
to seal fourfold.
Time: Regardless of cause, perforation should
be repaired as soon as possible to discourage
further loss of attachment and prevent sulcular
breakdown.

 Treatment sequence:
Perforation defect should be repaired before
proceeding with definitive endodontic treatment.
1. Haemostatics:
e.g. Calcium hydroxide, collagen, calcium surface.
- ferric sulfate, leave a coagulum behind that may
promote bacterial growth compromising the seal at
the tooth and illusrative interface.
2. Barrier Material:
 a. Resorbable. . Collagen materials: (Collacote)
2. Calcium sulfate: (Capset)
b. Non Resorbable. i) MTA (Mineral trioxide
aggregate)

 Apical perforations
This type of perforation occurs through the apical
foramen or through the body of the root.
 Etiology:
Instrumentation of canal beyond the apical
foramen. Incorrect WL or inability to maintain
proper WL causes blowing out of the apical
foramen
 Treatment: establish a new WL, creating an
apical seat and obturating the canal to its new
length. The new WL should be established 1-
2mm short of the point of perforation.

ZIPPING OR
ELLIPTICATION
 Transportation or transposition of the apical
portion of the canal

LOSS OF PATENCY
 Canal may suddenly loose patency during a
cleaning and shaping process.
Causes
 tissue compression,
 debris accumulation or
 instrument separation.

CONCLUSION
 The crux of endodontics revolves around efficient
& effective manipulation & obturation of the
apical third
 Appreciable knowledge of the morphology of the
root apex and its variance, ability to interpret it
correctly in radiographs, and to feel it through
tactile sensation during instrumentation are
essential for an effective rendering of the
treatment of root canals.

 A hallmark of the apical region is its variability and
unpredictability. Because of the tremendous
variation in canal shapes and diameters there is
concern about a clinicians ability to shape and
clean canals in all dimensions. The ability to
accomplish this depends upon the anatomy of the
root canal system, the dimensions of canal walls
and the final size of enlarging instruments.

Root apex and working length determination

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