Anatomy of apical third /certified fixed orthodontic courses by Indian dental academy

Anatomy of the
apical third
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


Achievement of a perfect seal at the apex using an inert
filling material is the ultimate goal for every endodontist. The
crux of endodontics revolves around the efficient and
effective manipulation and obturation of the apical third of
the root canal. The importance of a thorough cleaning and
hermetic filling of the apical part of the canal for successful
healing of the periapex was highlighted analogically as early
as 1939 itself, by Kronfeld.
Appreciable knowledge of the morphology of this ‘small
zone’ and its variance, ability

to interpret it correctly in

radiograph, and to ‘feel’ it through tactile sensation during
instrumentation are essential for an effective rendering of
the treatment of root canals.

CONTENTS
 Anatomy and Histology
 Eruption, Root Length and Apical Closure
 Morphology of Apical 1/3rd
 Anatomical variation and pathology in Apex
 Length determination at apex
 Instrumentation
 Preparation of Apical Zone
 Irrigation and Apex
 Obturation and Apex
 Repair at Apex
 Periapical Surgery and Apex
 Recent Advances


HISTORY
 1929 – Stallard stated that the final root end completion
occurs by down growth of the epithelial root sheath after
eruption and occlusal contact with opposing teeth.
 1980 - Ten Cate proposed that development of apical
foramina on number of invaginations of root sheath.
 Frank 1966, Steiner (1968) Heithersay (1970) Ham (1972
Holland et al (1973) – CaOH emerged as material of choice
for apexification.
 1955, 1956, 1960 – Green studied the correlation of apical
foramen to the actual www.indiandentalacademy.com
apex.


 1925 - Hess, 1960 – Kramer, Studied lateral accessory
canals and apical delta’s in detail.
 1958 – Kuttler detailed the cemento dentinal junction.
 1968 – Seltzer et al studied the deleterious effects of
overzealous

instrumentation

beyond

the

apical

foramina.
 1950 – Grossman suggested filling right to the apex.
 1951, 1958 – Kuttler suggested filling till CDJ.
 1976 - Altonen and Matilla concluded that insufficient
apical sealing as significant factor for failure of

periapical surgeries.

Anatomy of Apical Canal
According to Kuttler, 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 to this position as the minor diameter of
the canal, although others call it the apical constriction. The
diameter of the canal at the site of exiting from the tooth
(major diameter) was found to be approximately twice as
wide as minor diameter. This means that the longitudinal
view of the canal as a tapering funnel to the tip of the root is
incorrect.


Because the adjacent walls of cementum are slightly convex or
hyperbolic or funnel shaped when viewed in long section, the
configuration of the area between the minor and major diameters
resembles that of a morning glory of a flower.
Histological Development of Root Structures
During tooth development, the inner and outer dental
epithelium fuse to form the cervical loop, which invaginates into the
underlying connective tissue. The epithelial root sheath consists of
inner and outer epithelial cells.

The inner epithelial cells form a

filamentous layer which is associated with the basal lamina.

After making contact with the basal lamina of the
inner epithelial cells, the odontoblasts fully differentiate
and then produce dentin. Following dentin deposition, the
odontoblastic processes withdraw from the epithelium
and the outer layer of root dentin.
The root sheath determines the number, size and
shape of the roots (Ten Cate, 1965) and the future
cementoenamel junction.

It then becomes known as

Hertwig’s epithelial root sheath. The invaginated portion
remains as a continuous layer until the dentin of the root
is formed.


After
dentin,

deposition
Hertwig’s

disintegrates

in

of

root

sheath

a

coronal

direction following the ingrowth
of the connective tissue of the
dental sac.

When the root

sheath begins to disintegrate,
cells of the connective tissue
differentiate into cementoblasts,
and cementum is deposited on
the dentin.

According to Orban (1928), the root apex remains in
its

place

during

eruption,the

tooth

and

surrounding

supporting structures move occlusally, with continual root
formation. There is little bone formation opposite the root
apex, whereas large quantities of bone formed in the
bifurcation regions of the erupting teeth. After eruption and
occlusal contact with an opposing tooth, further down-growth
of the root sheath provides the matrix for final root end
completion (Orband and Mueller, 1929).


Eruption and Root Apex
Eruption represents the process of movement of the
teeth from their functional position in the dental arch.

A

unified concept has not yet emerged. Previous theories
have included the roles of collagenase in the dental follicle
(Cahill, 1970, Woessner and Cahill, 1974) and increased
pulpal pressure (Van Hassel and McMinn, 1972).
A predominant theory holds that the motility of the
periodontal fibroblasts actively generates the eruptive
force.


Root Length and Apical Closure

The root length and apical closure are completed
for the permanent teeth according to the following
schedule,

varying

somewhat

according

to

sex

differences.

It is obvious that mature root length is obtained
for all the permanent teeth, with the exception of the
second and third molars, by 12 years of age.

Ages of Tooth Eruption and Calcification of
Root Apices (in years)
Centr Later Cus First Secon Firs Seco
al
al
pid Prem
d
t
nd
olar Premo Mol Mola
Incis Incis
or
lar
ar
r
or
Erupt 6-8
ion

7-9

1012

9-11

11-12

5-7 12-13

Calci 10-12 11ficati
12
on

1314

12-14 13-14

10- 15-16
11


Clinical Correlations in Endodontic Therapy
Successful repair of inflamed dental pulps in teeth with
incomplete apical root closure is enhanced compared to that teeth
with

completed

root

formation,

possibly

because

of

the

unrestricted metabolism in the former group (Ouostarinen et al,
1966). Thus pulp capping or pulpotomy procedures have a better
chance for successful resolution in teeth with open apexes.

Once root end has been completed, complete endodontic
therapy has a better prognosis than pulp capping or pulpotomy
procedures.

APICAL PULP TISSUE
 The apical pulp tissue differs structurally from the coronal
pulp tissue.

The coronal pulp tissue consists mainly of

cellular connective tissue and fewer collagen fibres. The
apical pulp tissue is more fibrous and contain fewer cells.
 This fibrous structure appears to act as a barrier against
the apical progression of pulp inflammation. However, in
partial or total pulpitis complete inhibition of inflammation of
periapical tissue does not usually occur.

Clinical correlation in Endodontic therapy
A vital pulp extirpation involves severance of pulp
tissues somewhere in the apical region of main canal.
 Actually plane of severance of the pulp tissue from
the periodontal ligament is not under complete control
of operator.
The separation can occur anywhere in the root canal
or even beyond the apical foramen, somewhere in
periodontal ligament.
 When the latter type of pulp severance occur, the

ensuing hemorrhage causes painful pericementitis.

Blood & nerve supply – apical pulp
The fibrous structure of the apical pulp tissue supports the
blood vessel and nerves which enter the pulp.
The pulp of tooth is supplied by a no. of blood vessels which
originate in the medullary space of the bone surrounding root
apex.
The blood vessel course between the bone trabeculae and
through periodontal ligament before entering apical foramina
as arteries or arterioles.
The blood vessel ramify in the apical pulp tissue.

 These vessel are surrounded by large medullated
nerves which also branch after it enter the pulp.
 The intimate relationship of blood and nerve supplies
of the pulp and periodontal ligament provides a
background for the inter relationship of pulp and
periodontal disease.


Apical Dentin
 In the apical region, the odontoblasts of the pulp are absent or
flattened or cuboidal in shape.
The dentin that is produced is not as tubular as coronal dentin
but, is more amorphous and irregular.
This type of dentin is sclerotic dentin.
The amount of sclerotic dentin increases with age (Azaz et al
1977, Johansen 1971).


SEM and TEM studies have shown that the translucency of
the apical dentin apparently results from diminution in width
of the tubules.
 The dentin becomes optically transparent being uniform
enough to avoid scatter of transmitted light.


 The sclerotic apical dentin is considered less permeable than
the coronal dentin.

This reduced permeability is significant because the sclerosed
dentinal tubules are less readily penetrated by microbes and
other irritants.

 Towards the apex of teeth, the dentinal tubules appear to
blend with cementum canaliculi.


The apical foramina tend to become obliterated both by
the deposition of 20 dentin within root canal and by the
deposition of cementum outside the root canal.

 Continuous dentin and cementum deposition throughout
life gradually tends to reduce the width of apical foramina,
but complete closure does not occur as long as vital pulp
tissue remains.

Apical Cementum
Cementum formation begins in the more apical region of
the tooth, spreading toward the crown.

Cellular cementum containing cementocytes, is usually
found around apical and furcation regions of the tooth.

Sharpey’s fibres - 20µm, are embedded in both surface and
deeper layer of tissue.


When heavy stress is placed on tooth, thickened amount of
cementum is elaborated, increasing the area of periodontal
attachment and strengthening the supporting mechanism this increased deposition of cementum is in response to
function and is known as hypercementosis (hypertrophy).


“A

histological

examination

of

a

root

canal

demonstrate that we are dealing not with a canal but rather
with a root canal system complete with torturous turns,
apical foramina, at times with accessory canals. This ‘real’
picture is far different from image evoked by word-’root
canal”.
 This root canal system whose shape has been altered by
age, operative procedure, decay and trauma is unique for
each tooth and is different from tooth to tooth. A
standardized root canal is non existent.

- Lukes & Bolatin

Morphology of the Apical third
Root canal system :

•Apical part of root canal
•apical foramen
•Accessory & Lateral canal

Apical part of root canal
• Morphologically – this is the most complex region;
therapeutically-a challenging zone,prognostically – an important
part; unfortunately radiographically – the most obscure & unclear
area. However an endodontic treatment is almost always gauged
by the way the root canal filling appears in apical 1/3 in the post
filling X-ray.


A detailed knowledge of apical part of root canal system is
essential as it is common area for procedural error (e.g.
Ripping, zipping, ledging, false canal formation, instrument
breakage etc) during instrumentation.


Advancement in knowledge of the apical 1/3 has also
led to changes in procedural concepts. Currently, ‘effective
cleaning’ and irrigating technique without under / over
enlargement are favoured.
• The clinically significant features of apical part of root
canal system are:Accessory canals : Principal or main canal in a root may
communicate with surrounding Periodontium at any level
of root through “accessory or lateral canals” before exiting
from tooth at or near anatomic apex of root.

A lateral canal is a canal that is located at
approximately right angles to main root canal.

An

accessory canals is one that branches off from the main
root canal, usually somewhere in apical region of two root.
According to Green, the incidence of
accessory foramina ranged from 10%
in

maxillary

mandibular

central
cuspids

incisor
to

47%

and
in

mandibular 2nd premolar with other
teeth having incidences within this
range.

Lateral canals

by gross methods of

detection – vulcanite corrosion specimen of root
canals, have indicated that there is an incidence of
16.9% of such canals in all teeth (Hess 1928).
However

Seltzer’s

histological

examination

indicate that incidence is much greater.
According to Hess et al (1983), an accessory
canal foramina will have a mean diameter of 6 to 60
µm.

In anterior teeth, accessory and lateral canals were
observed in an incidence of 34%. In a no. of teeth a Y
shaped branching – dichotomy of the root canal near the
apex of the tooth were evident (histological section).
No relationship between presence of accessory canals or
foramina and age of the patient was apparent.
In molars, a multitude of accessory canals are present,
especially, within the cementum “web” fusing the roots.
The canals were filled with capillaries, pulp cells, ground
substance and fibers , confluent with pulp tissue.

In many teeth, however, the width of the accessory of
lateral canal is exceedingly small, permitting only the
presence of small capillaries and their supporting stroma.
Usually, these small canals cannot be observed in
radiography when interference occurs with the nutrition of
the pulp through involvement of these foramina

by

periodontal disease, small region of necrosis or infarction
occurs within pulp causing pulp tissue breakdown, fatty
degeneration and mineralization of pulp tissue.

Frequently, the canals in the distal roots of lower molars and
palatal roots of upper molars, fan out towards the apex in a
‘canoe – shaped’ arrangement.


Implications

of lateral and accessory canals in

endodontic therapy.
 The presence of multiple accessory and lateral canals is the rule,
not the exception, as can be discerned from the detailed studies of
Green (1955, 1960,1986) & Ainamo and Loe (1986).
 The no. of accessory canals in the root does not appear to be
significant factor in success or failure of endodontic therapy in teeth
with vital pulps. If they were, most endodontic therapy would fail.
It would be difficult, if not impossible, by our current techniques to
instrument and cleanse the accessory canals, even with thorough
reaming and filling.

 In teeth with totally inflamed or necrotic pulps, granulation

tissue is found in the accessory canals prior to endodontic
therapy.
 The significance of the involved tissue remaining in accessory
foramina as a factor in failure or repair after endodontic therapy
has not yet been definitely, determined.
 Following endodontics treatment, the pulp tissue in the
instrumented branches may become inflammed but usually
retains its viability with passage of time, continuous deposition
of dentin or cementum tends to narrow the lumen of these
canals.


Interestingly, although the incidence of occurrence of lateral
and accessory canal in human teeth is high and canals are
believed to have potential to harbor irritant and perpetuate
pathological problem, the percentage of failures due to
unfilled lateral canals is small in clinical practice.
It has been pointed out that this is probably because of
biological hard (cementum & dentin) closure of lateral canal
foramina subsequent to elimination of chronic inflammation of
the pulp or irritants from main root canal.

Reason biologically :2 changes happen as tooth become functional.
1. It is made to bear the biting stress which may move the
tooth is mesial direction.
2.

Occlusal load may disturb the curtain like HERS at apical
end.


•

Epithelium of HERS is required for initiation of
dentinogenesis in any given point of root.

•

Its absence causes development of accessory /
lateral canal. The root sheath should disintegrate
before dentin elaboration, to form a lateral canal.

•

In addition, accessory or lateral canals may results
from lack of dentin elaboration around blood vessel
which is present in periradicular connective tissue.


The preparation should extend to narrowest part of root canal
– apical constriction, the progress of root canal treatment is
then clearly at its best (Beer and Boumenn 1994)
The apical foramen is the circumference at end of root canal
where pulp tissue is continuous with apical periodontal
tissue.
The apical constriction lies within root canal just coronal to
apical foramen & corresponds to dentino cemental junction,
which is where the dentin of root canal meets cellular
cementum (Simon 1993).

1931- Grove recommended the DCJ as ideal end point
for root canal preparation.

The philosophy of correct end point for root canal
instrumentation is derived from extensive histological
study by Kuttler (1955) who calculated average distance
b/w centre of apical foramen and apical constriction in
people younger than 25 yrs to be 0.52 mm and 0.66 mm
is those older than 55 years.

Detecting location of apical foramen : X-ray cannot be
belittled here, determination can be made on radiograph
and may be supported by tactile feedback and
electronic aids. Blood or exudate on paper points are
also clues working length.


Shape :- This is the most naturally constricted point of main
root canal. Endodontic literature describes over all- shape of
apical foramen appropriately as ‘funnel – shaped’.
Significance : Apical constriction is of adv. during endo
therapy as it can act as a natural ‘stop’ during filling
procedure.

Maintaining the original position and shape of the apical
constriction are two main objectives of root canal preparation
procedure .

Foll. steps taken to maintain the original position & shape
of the constriction:
a. Working length of root canal should be measured
correctly.
b. Canal

patency

should

be

maintained

through

recapitulation
c. Proper and adequate irrigation of apical 1/3. Irrigate well
flush out the debris and dentin shavings, preventing
accumulation of ‘dentin mud’



Following endodontic treatment, a root canal filling to a

foramen that is not situated directly at the root apex would
appear short of the apex in a radiograph.


Most of apical foramina are not present directly at the apex

of tooth, an apparently well filled root canal that appears
flush with the apex in a radiograph is actually overfilled.


Repair of periapical tissue is then impeded because of the

presence of foreign body- the root filling material.

Radiographic assessment of apical 1/3 : following appearance of
apical 1/3 indicate deviation in internal anatomy.

Thin ‘pinched’ apex : over enlargement of the canal may lead to
perforation.

Bulbous apex : due to hypercementosis. In these cases apical
foramen / connection may be significantly shorter than radiographic
apex.

Resorbed apex : Advanced inflammation at periapex cause
resorption of cementum, dentin and widening of apical
foramen.

Blunder buss : X-ray of newly erupted tooth would normally
show an incompletely formed root having a wide root canal and
open apex. Standard root instrumentation and obturation
techniques not favorable as morphologically the wall of blunder
buss canals are thin and fragile particularly near apical 1/3.


CHANGES IN APICAL 1/3RD
According to Buchanan ‘calcification is a degenerative
process near site of injury, around pulp chamber and
progress apically. Therefore, there is always a path in any
calcified canal that is not obstructed.
The cognizance of the fact that deposition of calcific material
is more in the cervical part of the canal compared to its apical
part is of great clinical importance.

• Just enlarging of the orifice and cervical 1/3 of canal would
enable easier passage of even a relatively bigger instrument
directly to apex. The fact is, it is the cervical third of canal
which is generally narrower or more calcified.

The rule of the thumb of ‘3 yrs’ may be considered to
be true only for the completion of overall ‘length of root’ and
time schedule of 3 yrs need not be applied for completion or
maturation of the apex of root.

Thomas et al stated that

apices may not mature until 5 years after eruption.


Remodeling / deposition of cementum occuring at apex is an
ageing process. This probably occurs to compensate for
altered enamel, or due to physiological mesial migration of
teeth or as response to occlusal process.
As a sequel to deposition, there is an increase in overall
distance from the root apex to apical constriction of root
canal. (increase occurs b/w apex and foramen and foramen
to constriction).
This is of clinical significance as working length of tooth is
relatively shorter from the radiographic apex for an aged tooth
than its for a young adult. The diameter of the apical foramen

As age advances, the anatomical length of the root may
increase due to deposition of cementum, however the
working length decreases due to the deposition of 20 dentin at
the level of the apical constriction.

• Sclerosed dentin, narrowing obliteration of accessory
canals, and stronger apical dentin matrix due to thicker apical
cementum may be considered the reason for endodotic
therapy to be relatively more successful in older teeth.


Cemento dentin junction
Acc. to Kuttler (1958) the root canal is divided into a
long conical dentinal portion and a short funnel shaped
cemental portion.
The cemental portion is usually in the form of an inverted
cone with its narrowest diameter at or near the
Cementodentinal junction and it base at the apical foramen.
Occasionally the cementum abuts directly on the dentin at the
apex, at times, the cementum extends into the root canal,
lining the dentin an an irregular manner.
The extent of cementum deposition on each wall of the root
canal varies, one wall is usually covered with a greater
quantity of cementum www.indiandentalacademy.com
than the other wall.

No definite morphologic pattern of the CDJ is found
consistently. The thickness of cementum around the
apical foramen is inconsistent & varies greatly.


Guides to the position of apical foramen
Factors such as root curvature, areas of occlusal
stress,

amount

of

cementum

deposition,

and

tooth

morphology determine the position of the apical foramen to
the root. The film does not indicate if the exit occurs on the
buccal or the lingual surface.
However if it appears that the pulp canal space abruptly halts
at a point near the apex, it is usually indicative that the canal
does exit short of the radiographic apex on either the buccal
or lingual agent.

Anatomical variations and pathology in root apex
Apical Delta
The apical delta is Y-shaped branching of the root
canal near the apex of the tooth. Such apical deltas were
found to be frequent by Seltzer et al 1966 and Hess et al
1983.
It is difficult to instrument and obturate both the
branches. If it is not visible in radiograph, it may be left
untreated. The pulp tissue in the branches may become
inflamed, but continuous deposition of dentin or cementum,
tends to narrow the lumen of these canals.
Recent thermoplasticized root canal filling – like obtura and
thermafill obturate these variation more successfully.

Denticles (Pulp stones)
Pulp stones form around foci of mineralizing pulps tissues
components such as collagen and nerve fibres, blood vessels
ground substance, inflammatory and necrotic cells.
Pulp stones in apical 1/3 of roots are present in approximately
15% of the teeth and more than one stone is usually found
(Seltzer et al, 1966).


Clinical correlation in Endodontic therapy

The denticles that are found within
pulp tissue in apical third of the root may
account for some difficulties in root canal
instrumentation. During reaming and filing
of the root canal, they may become
detached and impacted into apical foramen,
rendering further instrumentation difficult.


Apical calcification
In case of chronic inflammation, ageing etc. the
calcification of the root canal occurs. In some root canals the
apical 1/3 are calcified, complete obturation of such cases
would be difficult.

Effort should be made to negotiate the

canal with help of EDTA and thin files.


ISTHMUS
 An isthmus is defined as a narrow strip of
land connecting two larger land areas or a
narrow anatomic part or passage
connecting two larger structures or cavities.
 Green in 1973 described the isthmus as a
corridor between the two roots.
 The ishmus connection can be observed
between two root canal systems that occur
within one root

ISTHMUS FORMATION
 The actual formation of the isthmus is from the
embryonic origin is through the epithelial root
sheaths.
 In teeth with single roots, the inner cells of the
root sheaths next to the dental pulp
differentiate in to odontoblasts and start
secreting dentin matrix.
 As the matrix is laid down and begins
mineralizing ,the epithelial root sheath cells
secrete a thin layer of cementum on this newly
formed dentine.

ISTHMUS CLASSIFICATION
 Type I –Two or three canals with no notable
communications.
 Type II – Two canals that possessed a definite
connection between two main canals.
 Type III – Three canals that possessed a definite
connection between three main canals.
 Type IV – when canals extend into isthmus area.
 Type V – True connection or corridor throughout
the section.

Incidence of Isthmus
 The incidence of isthmus is highest in the apical
3-5 mm levels.
 In teeth that have two canals , the 4 mm sections
contain an isthmus 100 % of the time
 In the mesial root of the mandibular first molar ,
the incidence of two canals increases as the cut
levels goes up.The highest incidence of isthmus at
4 to 6 mm.

Clinical significance
 Conventional mechanical cleaning and
shaping methods can not physically
debride this vitally important area.
 The only way to clean such anatomic
variations is through the use of
chemical irrigants such as full strength
sodium hypochlorite.

 This area which can lead to failures
of conventional orthograde
endodontic treatment must also be
considered in failures of traditional
endodontic surgery.
 The tissue that can be left over after
traditional surgical procedures with
a micro head handpiece and micro
burs can be a nidus for recurrent
infections.

 Mechanical cleaning ultrasonics and their
associated tips have aided in thorough
debridement of the apical root canal
system

 The recognition and management of the
canal isthmus is the one factor that may
improve the success rate of surgical
endodontics in posterior teeth.

Open Apex
Endodontic management of the pulpless, permanent teeth
with wide open blunder buss apex offers dentists a most
difficult condition to treat.
Problem of open apex - the open apex occurs when trauma
or caries cause pulpal exposure prior to the completion of root
development.
An open apex refer to absence of sufficient root development
to provide a conical taper to the canal - “Blunderbuss” canal.
Since it is necessary to seal the apex to gain endodontic
success, it is physically impossible to achieve this objective
through ordinary procedure in open apex cases.

Before introduction of apical closure techniques, the
usual approach to this problem was surgical.
The preferable solution,however, is to allow the apex
its complete development.
Treatment of open apex with vital pulp - A pulpotomy
procedure is indicated in the tooth with an open apex
to allow completion of apical closure, as long as
apical pulp remains vital.

This is referred to as

apexogenesis (physiological) when the apical pulp
can be retained in vital condition, the root end and
canal usually will
and shape.

assume a relatively normal size

Apexification procedure – treatment of
open apex with non-vital pulp.
Apexification

is

a

method

to

induce

development of the root apex of an immature,
pulpless

tooth

by

formation

of

osteocementum or other bone –like tissue.


The most widely accepted technique involve
cleaning and filling the canal with a temporary paste
to stimulate the formation of calcified tissue at the
apex.
 An alternate approach on which a material is
placed into the apical 2–4 mm of blunder buss canal
to act as a barrier agent into which guttapercha is
condensed is becoming accepted as treatment of
choice.


Many materials have been reported to successfully
stimulate apexification. The use of Ca(OH)2 for apexification
in pulpless tooth was first reported by Kaiser in 1964. The
technique was popularized by Frank.
The Ca(OH)2 has been mixed with

CMCP, metacreysl

acetate, cresannol, physiologic saline, ringer soln, distilled
water.
Tricalcium phosphate, collagen Ca phosphate, osteogenic
protein-1, bone growth factor, MTA.

 But the most important factors is achieving apexification
seems to be thorough debridment of root canal (to remove
all necrotic pulp tissue) and sealing of the tooth (to prevent
ingress of bacteria and substrate)

Ca(OH)2 technique
Commercial paste (e.g. Calasept, pulpdent, calyxyl) may be
used to fill the canals.

The usual time required to achieve apexification
is 6-24 months (average 1yr + 7 months)
Patient is recalled at 3 months intervals for
monitoring of the tooth.
After clinical verification of apexification made
by failure of small instrument to penetrate
through apex, canal is obturated with GP in usual
manner.


Histology of apexification with Ca(OH)2
The calcified material that forms over apical foramen has been
identified as osteoid (bone) or cementoid (cementum like)
material. The formation of osteodentin also has been reported.
Histologic studies consistently report absence of HERS normal
root formation usually does not occur after apexification. Instead
there appears to be a differentiation of adjacent connective
tissue cells into specialized cells, there is also deposition of
calcified tissue adjacent to filling material.
The closure of apex has minute communication with periapical
tissues. For this reason apexification must always be followed by
filling of canal with permanent root canal filling.

Apical root resorption
Apical periodontitis
resorption.

with

apical

root

Practically all teeth exhibiting apical
periodontitis exhibit root resorption. The
resorption can be minor & practically
-invisible radiographically or can be so
extensive that a significant amount of root tip
is lost.


•The cemental layer is a physical barrier that
separates the root canal system from
surrounding periodontal attachment. It
appears that the intense & progressive
inflammation confined at the apex overcome
the resistance of the cemental layer to
resorption.
• Radiographically it is diagnosed by
radiolucencies at root tip and adjacent bone.


Length determination
Determination of working length is
obtaining the hermetic seal,as wrong
lead to enlarged foramen resulting in
1. Periapical irritation
2. Possible weeping of the canal
3. Lose of control during obturation
short of foramen with resultant
accumulation of dentinal mud.

an essential step in
estimation could either

or lead to preparation
ledge formation and

The clinician should try to determine the foramen constriction
by “Tactile sense”. He should be able to “feel” the foramen
and then confirm by any recent electronic method.
Common Methods include :
Radiographic, Tactile,www.indiandentalacademy.com
paper point evaluation, electronic aids.

Electronic apex locator are also important adjuncts to
length determination. At this time they are not accurate
enough to replace traditional radiograph but are useful
in establishing estimated lengths & finalizing working
lengths in cases were apex cannot be visualized.
Based on three different electrical principle

Electrical resistance : Resistance locators are based
on fact that electrical resistance between periodontal
membrane & oral mucosa is constant. The RAL was
first to be developed and utilized a direct current. The
early model was often inaccurate in presence of vital
pulp, tissue, solution – irrigants, tissue fluids, blood,
pus & local anesthetics & when contacting metallic
restoration. E.g., Neosono McPlus, Digipex III, Apex
finder.

Impedance type : Require calibration &
operate on principle the tooth is hollow
tube with closed end. There is electrical
impedance across the walls of the canal.
At the CDJ there is an abrupt decrease in
impedance which is detected by the unit
indicating the apical termination. E.g.,
Endocator


Frequency dependent : Operate on the principle that
there is maximum difference of impedance between
electrodes depending on 2 frequency waves employed. The
instrument is calibrated by inserting the file into coronal
portion of the root canal where difference between 2
frequencies is constant. The max difference in impedance
between 2 frequencies is at apical constriction.


Advantage : Operate in fluid environment.
E.g., Root ZX, Endex.
Disadvantage : Do not reveal the number,
curvature, width, other complexities of root canal.
Are not consistent with their performance. Might
give false reading.


Controversy exists as to the length of root canal be prepared
& subsequently obturated. Theoretically, the canal should be
prepared to CDJ, however translating this histological entity
into a clinical reality is not possible. In addition, the CDJ is
variable within apical portion of the canal. For this reason
most clinicians calculate the corrected working length
empirically, others view radiographic apex as the only
consistent reproducible point.


A rational approach to establishing corrected
working length can be obtained from review of the
apical anatomy & correlating this information with
presence or absence of pathosis.


Burch & Hales noted that foramen deviated from
apex - 92.4% of the time & average distance
was 0.57mm.
Chapman in studying anterior human teeth noted
the apical constriction lies between 0.5mm to
1mm 92% of the time. The average foramen
diameter was 0.297mm for max
0.260mm for mandibular teeth.

teeth &

Dummy et al found average apex to constriction
distance was 0.89 and 95% of constriction were
between 0.5 to 1mm from apex.
It has been demonstrated that when periradicular
lesion is present root resorption that is not
radiographically visible is likely. This will affect the
clinicians ability to establish a seat a stop for
maintaining the obturating material.


When

the

periapical

tissue

exhibits

normal

structures, the corrected working length should be
established 1mm from radiographic apex. This will
account for apex to foramen difference.
When bone resorption is evident the corrected
working length is established 1.5mm short of apex
and when bone & apex exhibit resorption the length
should be 2mm from apex (or POE).


Weins modification

One constant in length determination is the fact that
preparation & obturation to radiographic apex is
beyond the apical constriction. Prognosis studies
indicate that success rates are higher when
obturating materials are confined to root canal space.


Biological rationale for working length
The most clinically relevant working length landmark is
the constriction - the narrowest point of canal & therefore
the narrowest diameter of the blood supply. Beyond the
constriction, the canal Widens & develops a broad
vascular supply.
Therefore from biological perspective, the constriction is
the most rational point at which to end canal preparation,
since the existence of functional blood supply controls the
inflammatory process. Intra radicular termination of the
clearing process leaves a canal contact interface equal in
area to the inflammatory process (1:1).

Termination beyond the constriction provides a
greater area of blood supply than of irritant interface.
Extra radicular termination of working length can
theoretically provide a hemisphere of vascular support
to the inflammatory process. This gives a numerically
superior advantage to inflammatory process.


The surrounding vital tissue have more capacity to destroy
irritants and restore the area to a biologically functional state
cleaning & shaping to apical constriction allows the
inflammatory healing mechanism to complete.
Optimal length
From a procedural perspective it is advantageous – to treat till
the constriction that can be felt by the experienced. After
coronal shaping, the experienced hand can detect an abrupt
increase in resistance followed by rapid decline as instrument
tip passes beyond constriction. This preparation shape helps
to optimize the apical seal when the canal is subsequently
filled.

The radiographic apex is where the root apex appears to join
PDL. The vast majority of endodontists prefer filling the canal
to DCJ so as not to impinge on periapical tissue, permitting,
hopefully physiologic closure of root canal by cementum.
Filling the canal so it appear flush with radiographic apex
produce esthetically pleasing radiographs, however in reality,
the filling is probably slightly overextended, especially in roots
curved in bucco-lingual direction.


The most desirable vertical extent of root canal filling is
a homogenously dense filling extending 0.5 – 1mm
short of radiographic apex.


Instruments & Instrumentation
Improperly prepared access cavity would presupposedly
affect the preparation of the apical zone. Impingement of
the endo instrument coronally would result in either ripping
of the foramen or formation of a ledge.
Ninety percent of the canals are curved (Christie & Peikoff
1980); and precurving of the files is a must in all such
cases.
Files are not to be given 1/4 turn bites into dentin or pulled
forcibly with lateral pressure along the canal walls when
preparing the apical end of the canal.


Rotation of instruments has been found (Weine et al. 1975)
to violate the basic principle as it forms an ‘hour-glass’
outline rather than a smooth taper near the apex.
Flexible files are preferred over stiffer varieties since they
may change the course of the canal, form a ledge or or
transport the foramen by ripping.
D-type files (produced from rhombus blanks) are more
flexible than regular K-type files (produced from square
blanks) (Anderson et al. 1985).
The new K-type file –triangular in cross section – is more
flexible than H-file (Roane et al. 1985).

Successful treatment in dependent on diagnosis, treatment
planning

skills,

knowledge

of

radicular

anatomy

&

application of cleaning & shaping procedure. Careful
pretreatment evaluation is essential prior to RCT to assess
possible complicatory factors.
In 1974, Schilder outlined the principles of cleaning &
shaping,
• Cleaning is removal of all contents of root canal system
before & during shaping, infected material, antigenic
material, organic substrates, microflora, bacterial by
product
Food, caries, tissue remnants, pulpstone,
collagen, contaminated canal filling material & dentinal
debris.

Apical shape.
The ideal apical shape is to leave natural apical foramen
alone, clean it so that it is patent & obturate it 3
dimensionally. The last few mm of canal that approach
apical foreman are critical in that the shape developed
there must be tapering tunnel form that allow distortion of
obturation materials by compacting into the asymmetric
perimeter of foramen.

Serial shaping techniques
Schilder stressed on 5 mechanical objective for successful
cleaning & shaping.
Mechanical objective a) develop a continuously tapering conical form in the root
canal preparation.
b) make the canal narrower apically with the narrowest
cross sectional diameter at its terminus.
c) Make the preparation in multiple planes
d) Never transport the foramen
e) Keep the apical foramen as small as is practical.
The mechanical objective are in harmony with natural root
canal anatomy.

An additional objective is adequate preparation of the
apical region.

Preparation of Apical Zone
An apical control zone establishes an apical constriction
by forming rapid canal taper at a clinician defined location.
This is near location of natural constriction but is
mechanically defined relative to canal exit itself.


This procedural nuance eliminates extensive searching for
the natural constriction. Preparing to natural constriction is
difficult

because

of

great

variability

in

location

of

constriction. Properly done, a control zone dependably &
easily establishes a round & clear apical foramen for
obturation.
Apical foramen patency
Confirming apical foraminal patency is the last step for any
cleaning & shaping. It is a feature of control zone and is
important to provide a complete severance of the pulp from
PDL. Endodontic files lack sufficient sharpness the cut
fibrous Connective tissue unless tissue is engaged between
cutting edges & canal wall .

To assure that a severance occur near the PDL, the clinician
must complete the patency opening with the first file that fits
tightly in the foraminal passage.


The master apical file - largest file to bind slightly at
corrected working length following straight line
access. It is determined by placing successively
larger files to corrected working lengths until a file
binds.
This process defines the size of the canal in the
apical 1/3 of root prior to cleaning & shaping. Pulpal
severance is accomplished by extending the file just
through apical foramen and with a very light pressure
rotating it one revolution to cause the cutting edges to
engage trap, & severe the remaining tissue.

Canal preparation is considered complete with the production
of a tapered preparation with placing smooth walls.
But even more critical is the creation of an apical matrix
constriction.
The apical matrix has 2 purposes
- To help confine instruments materials & chemicals to canal
space
- To create (or retain) barrier against which guttapercha can
be condensed.


After cleaning & shaping procedures the apical configuration
should be assessed. This is accomplished with master apical
file & smaller files.
Apical stop – A barrier prevents the master apical file &
smaller files from being placed beyond the corrected working
length.
Apical seat – A barrier prevents the master apical file from
being extended beyond the corrected working length but
smaller files pass through the apical foramen & beyond the
corrected working length.
Open Apex – The master apical file will pass through apical
foramen, it resembles an open cylinder.

Apical clearing
It is performed in cases where there is an apical stop. This
procedure enlarges and opens the canal in apical region at
the correct working length. It consist of 2 parts 1. Final
apical enlargement, 2. Dry reaming.

Final apical enlargement – This step is done after canal
preparation is complete & has met criteria for adequate
cleaning & shaping. Instead of final recapitulation,
instrument 2 to 4 size larger than MAF are carefully
reamed in clockwise manner at working length in wet
canal. Therefore final apical size in a smaller canal would
be a 35 # 40.

When used in a rotational fashion, the
instrument become centered and remove dentin
uniformly from the canal walls producing round
prep. Since apical enlargement is only
performed after establishing a coronal taper,
transportation of canal is eliminated.
Final apical enlargement is not done in canals
greater than size 40. if MAF size is already
greater than 40 and there is an apical stop, dry
reaming is done with MAF only.


Dry reaming is done after final apical enlargement & irrigation
and drying with paper points. The last size file used for final
apical enlargement (or MAF of larger than size 40) is then
spun carefully in a clockwise manner to length. This is the
final apical file (FAF), it removes dentin chips that pack
apically during drying.

Clinical description - The access cavity is aligned to provide
straight unimpeded entry into canal orifice. The chamber &
canal are irrigated with NaOCl. The orifice of each canal is
identified with an endodontic explorer.
Then No. 15 Flex-R files is marked with rubber stop to identify
approx. length of canal as it appears in pretreatment
radiograph.

Roane et al. (1985) introduced a new balanced force concept using
the latest K-type file triangular in cross cut, for the preparation of
apical zone in deeply curved canals.


Change in path of canal result from exertion of unbalanced
forces (Miserendno 1994). The objective is minimum
alteration of canal course.
Significantly less dentin debris is pushed out through apical
foramen than with step back technique (McKendry 1990).

Then the MAF is determined by placing successively larger
files to corrected working length until a file binds slightly.
This process defines size of the canal in apical 1/3 of root
prior to cleaning & shaping.

Step back technique
Flared preparation provides a cleaner environment, better
receptacle for the obturating material, and a stronger apical
dentin matrix (Weine 1982). Chances of apical ripping and
shifting in foramen are less with step-back technique (Christie
& Peikoff 1980).
Because there is very little canal enlargement and removal of
dentin near the apex, danger of perforation is reduced. Here
the apical portion is instrumented first, then coronal portion is
shaped.
Frequent recapitulation -sequential reuse & reentry of
previous instruments, ensure canal remain patent.

Instrumentation of fine curved canals is difficult because the
canal lacks natural taper. The clinician must develop this shape
during prep. phase of treatment.

Loss of length is common procedural error.
Two common causes for loosing length are failure to maintain
accurate measurements and packing debris into apical portion
of canal. Recapitulation with small files & copious irrigation after
each successive file size can prevent packing of dentinal
debris..

Then complete the cleaning and shaping by redefining the
control zone and establishing apical patency.
The fundamental technique are patency confirmation & serial
carving.

Step down technique
In this the coronal portion is enlarged first, only then the
apical portion of root prepared.

An adv. is coronal

enlargement makes it possible to insert the irrigating canula
quite deeply into root canal.

TRANSPORTATION
Transportation and ledging occur primarily in curved
canals. This error can be prevented by maintaining
a small AMF (#20 #35), by coronal flaring, by step
back prep


Blockage of canal system
Def : A blockage is an obstruction in a previously
patent canal system that prevents access to the apical
constriction or apical stop.
To prevent –
• Constant flushing and removal of debris by copious
irrigation
• File, used sequentially and never binding to canal.
• Recapitulation
When blocked – a small file with 450 curve at apical 34mm, inserted and rotated circumferentially
‘catch’.

to detect a

After negotiating canal to length, H file used to

remove debris.


Fractured instrument
 If an instrument breaks off in the apical third of a
narrow curved canal and the fragment is stuck too
tightly to be removed
 An attempt is made to by-pass the fragment,to
carefully enlarge the canal and to fill it with
guttapercha.
 Steel instrument fragments that are left in the
canal are relatively inert, and no signs of corrosion
were detected with SEM.
 Silver point fragments corrodes and must be
removed.

Altered foramina
Ledging (Internal transportation)
Def : A ledge is an artificially created irregularity on the surface
of root canal wall that prevents placement of instruments to the
apex of an otherwise patent canal.
Cause : Insertion of un-curved instruments
short of working length with excessive apical
pressure. Canal wall is gouged resulting in
ledge formation.
Prevent :

Pre-curve apical 3-4 mm. Do not force, rather
tease to most apical position.
Sequential and circumferential filing essential

Zipping (Elliptication)
-

Transposition or transportation of apical portion of normally

curved canal that has been straightened especially in apical
1/3.
Reason : Failure to pre-curve file, rotation of instruments in
curved canals, use of large stiff instruments to bore out curved
canal.
Apical foramen tend to be tear drop shaped or elliptical,
transported from the curve of canal.
When a file is rotated in curved canal – a biomechanical defect
– elbow will form coronally to elliptically shaped apical seat.
This becomes the narrowest portion of the canal.
Obturation terminate at elbow, leaving unfilled zipped canal
apical to elbow.


 Funnel formation:
 An apical funnel is the result of improper
instrumentation and straightening of the
apical portion of the root canal.
 To avoid this the apical end of the
instrument must be bent even more than the
curvature of the canal on the radiograph.


Prevention :
• File over curved in apical 3-4 mm
• Do not rotate file
• Bulk of cleaning and shaping
performed with small, flexible
files to enlarge apical seat.
• Anticurvature / reverse filing

Use of thermoplasticized GP, Ca(OH)2 root canal sealer.

Irrigation and Root apex

Canal preparation require the removal of either vital or necrotic
pulp tissue. While canal preparation is primary mechanism for
removal of canal contents, irrigation is essential regardless of
preparation techniques.

Irrigants are important for removal of dentin chips & tissue debris
produced during cleaning and shaping. The depth of needle
penetration & volume of irrigant delivered are important factors.
Proximity of needle to apex plays a important role in removing
debris, therefore the size of canal is an important factor in
determining effectiveness.

Smear Layer Management
When blades of any file engage and cut dentin - a smear layer
forms on the walls of preparation.
Frequent irrigation in conjunction with clearing and patency
files, reduce but do not eliminate the smear layer.
Aqueous 17% EDTA flooded into canal for 1 min. show to
eliminate SL.
Microbrushes introduced to optimally finish preparation can be
used in either rotary or ultrasonic hand piece.

Obturation and Root apex
With proper canal preparation, Obturation is one of personal
choice.
Radiographic assessment is the most common method for
determining the adequacy of root canal obturation.
The radiographic criteria including length, voids & shape.In a
properly filled canal GP will be at the prepared length &
without voids. The shape will reflect a tapered prep.with
apical extent coming to a point.
Obturation is a reflection of the cleaning & shaping procedure.


Distance from the apical foramen to constriction depends on
multitude of factors, Such as increased cemental deposition,
radicular resorption. Both process are strongly influenced by
age, trauma orthodontic moment, periradicular pathology or
periodontal disease.
If a major goal of RCT is to create an environment conductive
to regeneration of cementum over the apical foramen, the
periodontium that enter the apical foramen in teeth with vital,
Yet compromised pulps should not be challenged with
extrusion of root canal filling material beyond the end of
canal. This concept has been scientifically valid for 65 yr & is
supported by numerous retrospective studies.

Overfilling denotes “Total obturation of root canal space with
excess material extruding beyond apical foramen”.
Over extension denote extrusion of filling material beyond the
apical foramen but with the case that canal has not been
adequately filled and the apex has not been sealed.

The major cause of placing the root canal filling material
beyond the apical contriction in either overfilling or over
extension, when lateral or vertical compaction technique are
used,are the follo.:

• Excessive instrumentation (over instrumentation) beyond
the apical constriction resulting in the lack of an apical
dentin matrix.
• Unanticipated communicating
resorptive defects in the canal system.
• Defects incorporated into canal system
during cleaning & shaping - zips, perforation etc.
• Excessive compaction forces
• Excessive amount of sealer
• Use of too small a master cone
• Excessive penetration of compacting instrument.

Contemporary endodontic practices and long term evaluation
studies favor (Histologically also) obturation within the
confines of the canal system in all cases in an attempt to
prevent further challenge to the already compromised and
challenged periradicular tissues.
A serious effort to compact the filling material vertically
therefore should be made to obtain a dense, homogenous
appearing filling in its entire mass. Although tight apical seal
is of prime importance for success of endodontics treatment
the sealing of accessory canals is no less imp in enhancing

the chance of success.

(Nygard – Ostby, Blaney, Strindberg, Horsted & Nygard).
• Stating the space between GP & tissue surface was filled
by new connective tissue within a few months.

The Washington study also found no failure among those
well obturated cases in which the filling terminated slightly
short of the apex whereas 3.85% of the failure were caused
by overfilling.


Ingle (1956) determined 63% of the root canal failures to be
due to inadequate filling. The necessity to provide hermetic
sealing of the apical foramen as well as filling of the
accessory canals has brought forth many dynamic changes
in the obturation techniques.


The current trend in endodontics is towards the provision of
an impression – like filling of the root canal and its
ramifications with perfect adaptation, and inducing closure
of the foramen/foramina by hard tissue formation.
Guttapercha - Hill (1847)
- Bowman (1867)
It is compatible, thermoplastic, and adaptable (Nguyen
1984).
Negm et al. (1980) have recommended the use of gutta
percha coated silver cones as the core material.

Apart from lateral condensation technique and organic
solvent-softening methods, a few more techniques have
been developed in the recent years, showing promising
results, utilising the thermoplastic property of the gutta
percha, as the thermoplastic gutta percha was found to flow
and adapt close to the canal wall.
Almost all the studies done comparing the sealing abilities
of lateral, warm vertical, automated thermatic; condensation
and injected thermoplastic gutta percha, have shown their
sealing efficiency to be more or less similar (Evans & Simon
1986; Torabinejad et al 1978; Benner et al 1981; Lugassy &
Yee 1982)


Warm guttapercha vertical condensation
technique - Schilder (1967).
Comparing

the

sealing

vertical

abilities

condensation,

by

lateral

condensation, and automated thermatic
condensation, Wong et al (1981) found
that the vertical condensation gave the
best replication of the canal system.
This technique - time-consuming. But the
material

often

fills

the

accessory

ramifications.
Its use is recommended for most of the
clinical cases (Nguyen 1984).

Weine (1982) recommends this technique to be the best
when the fitting of a conventional master cone to the apical
portion of a canal.
Automated thermatic compaction of guttapercha - John
T.McSpadden.
Using a reverse-Hedstroem file-like instrument. Fits into the
slow speed contra angle handpiece.
Advantage - Time saving.
Disadvantage - Use is limited to straight and slightly curved
canals only.

Injectable thermoplasticized guttapercha delivery system
has emerged in the recent years showing promising
results. It has been reported by Yee et al (1978) to produce
impression – like reproduction of the prepared root canals.

Recently, a warm lateral condensation technique has been
introduced by Martin * (1986) using a thermal endodontic
condenser system. Though it is claimed to produce good
adaptation with dense filling, this device is yet to be
studied.


Fewer stormy postoperative reaction can be expected if canal
instrumentation and filing are limited by their narrowest waist of
the apical foramen.
Occasionally even though proper techniques has been foll. GP
or root canal sealer may be unintentionally pushed beyond the
confines of root canal system.
However the GP is a bacteriostatic substance that is generally
tolerated by peririradicular tissues. Although sealers may
promote an initial inflammatory response, over a short period of
time, the macrophage scavenger system eliminate the
excessive material from the periradicular tissue.

In either case,the mere placement of filling material
outside the canal system is not a major cause for
alarm if the canal space is 3 dimensionally obturated
because of the rich collateral blood supply & excellent
immunological capacity of periradicular tissues.


Repair of tissue following RCT
In teeth with preexisting periapical inflammatory lesion,
debridment of inflammed or necrotic tissue within root canal
begins process of repair.
Histopathology of repair
Granulation tissue
Neo Vascularization
Fibroblasts + Ground substance + Fibroplasia.
Cementum + Bone apposition (6 months)

Alternate filling techniques of apical 1/3
There are some techniques is which a barrier is created in the
apex against which the root canal filling materials can be
compacted.
Dentin chip apical filling
A method often used to create an apical stop for the purpose
of obtaining a biologic seal, support the placement of dentin
chips or other artificial barrier (i.e. Ca(OH)2, demineralized
dentin, collagen) before canal obturation.
Ironically the packing of chips may occur inadvertently during
cleaning & shaping, Especially if a patency file is not used
routinely.

The premise that dentin filling will stimulate osteo or
cementogenesis is well founded.
Gottileb & Orban, Ketterl reported cementum like closure at
the apex around dentin chips.
Baume, Oswald & Friedman described osteodentin closure

Holands, however, found the dentin chips,
if infected, are a serious deterrent
to healing.
Torneck found that dentin chips may
actually irritate & hinder repair.

In addition to possibly creating biologic seal, the packed chips
may assist in confining irrigating solution to the canal and
preventing overfilling, especially when canal has seen over
instrumented.
Favorable periradicular tissue response have been noted with
enhanced healing, minimal inflammation & apical cementum
deposition.


Ca(OH)2 apical filling
The success of Ca(OH)2 formulation in achieving apical
closure has stimulated use

of calcium compounds as

sealers, pastes, filling or apical plugs.
One investigation found that Ca(OH)2 produce a periapical
response that overall is indistinguishable from that produced
by dentin plugs.


CaOH2 may be carried into canals by means of small
amalgam carrier .
messing carrier- with curved tips
• small plugger is used to push & pack the material apically
•
Even with promising data that support the potential use of an
artificial barrier in apical portion of the prepared canal the
routine clinical use of this technique does not appear to be of
standard care

A material with predictable inductive capabilities is necessaryone that seals the canal, negates any bacterial influence,
stimulate cementum regeneration across apical foramen

Apical Root Fractures
Pulp necrosis occurs in 25% of root fractures.
Endodontic treatment is indicated in coronal segment only,
unless periapical pathology is seen at apical segment.
Treatment Option
When fracture segment in apposition :
If asymptomatic - keep under observation. Adjust occlusion of
tooth (splinting). Splinting follow-up - 3.6, 12 months interval.
If symptoms present - treat with non-surgical RCT in both
segment, if possible.
If symptom continue - surgically remove segment.
When fracture segment not in apposition :
Root tip may have to be surgically removed.

POST ENDODONTIC
RESTORATION
 The endodontically treated teeth are usually
restored with a post, a core and an artificial
crown 2 protect them from fracturing.
 Encroachment on the apical 1/3rd of the root
canal filling could disturb the apical seal
during post space preparation
 Weine stated that to leave 3 – 5 mm of
apical material intact is sufficient to ensure
sealing of the apex.

Periapical surgery and root apex
Periradicular curettage only eliminate egress of
microbes and not the cause. Curettage done alone (without
apical resection) will invite recurrence of lesion.
Root – end resection
Ablation of the apical portion of the root and attached
soft tissue
For :
• Creation of an apical seal
• Removal of pathologic process
• Removal of anatomic variations
• Removal of operator errors in non surgical treatment
A root resection of 3 mm at 0 degree bevel angle (90 0 to long
axis of root) removes the majority of anatomic variations.

Root end preparation
Def : Sealing the apical extent of the root canal system through
cavity preparation in the resected root end and placement
of a restorative filling material.
Types
1) Long axis preparation
2) Preparation perpendicular to the cut root surface (common
approach)
3) Vertical slot preparation (matsura)
4) Transverse slot preparation
Root end filling materials : ZnOE, Cavit, Diaket, GIC, bone
cement, IRM.

Repair following periapical surgery
Following surgery blood clot forms at site.
Granulation tissue fills defect.
Bone regeneration (lamina dura).
Callous formation

lamellar structure. 8 - 16 weeks

Regeneration of PDL - 8 weeks - functionally oriented.
Cemental regeneration - 8 weeks - even thickness of
cementum.

Recent advances
 Co2 and Nd:YAG laser is used for the
sealing the apical delta.
 Tri-Auto ZX was used to prevent over
instrumentation, file breakage and canal
transportation with its auto apical reverse
system.


Conclusion
The

morphological

variations

and

the

technical

challenges involved in the treatment of the apical third
seems infinite. Fracture of the apical third, resorption,
weeping apex, immature foramen are some of the areas
which continue to invite fresh views from clinicians and
researchers.


References










Pathways of pulp - Cohen 7th and 8th edition
Endodontic therapy Weine
Endodontics - Ingle 4th
Endodontics – Harty
Endodontology – R Beer baumann
DCNA -Microscope in endodontics
Endodontics – Jacob Daniel
Oral histology - Orbans
Oral histology - Ten cate

Leader in continuing dental education


Anatomy of apical third /certified fixed orthodontic courses by Indian dental academy

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