Working length in root canal treatment /certified fixed orthodontic courses by Indian dental academy

WORKING LENGTH DETERMINATION

INDIAN DENTAL ACADEMY
Leader in Continuing Dental Education
www.indiandentalacademy.com

WORKING LENGTH DETERMINATION


DETERMINATION OF WORKING LENGTH
The determination of an accurate working length is
one of the most critical steps of endodontic therapy.
The cleaning, shaping, and obturation of the root
canal system cannot be accomplished accurately
unless the working length is determined precisely.


Diagrammatic view of the periapex.


DEFINITIONS &TERMINOLOGY

the endodontic Glossary as “the distance from a coronal
reference point to the point at which canal preparation
and obturation should terminate,”
The ideal apical reference point in the canal, the “apical
stop,”
The anatomic apex is the tip or the end of the root
determined morphologically,
The radiographic apex is the tip or end of the root
determined radiographically.

The apical foramen is the main apical opening of the
root canal. It is frequently eccentrically located away
from the anatomic or radiographic apex.
Kuttler’s investigation showed that this deviation occurred
in 68 to 80% of teeth .


The apical constriction (minor apical diameter)
is the apical portion of the root canal having the
narrowest diameter. This position may vary
but is usually 0.5 to 1.0 mm short of the center of the
apical foramen.
The minor diameter widens apically to the foramen (major
diameter) and assumes a funnel shape.


The cementodentinal junction is the region where the
dentin and cementum are united, the point at which the
cemental surface terminates at or near the apex of a
tooth.
It must be pointed out, however, that the
cementodentinal junction is a histologic landmark that
cannot be located clinically or radiographically.


Clinical Considerations
Before determining a definitive working length, the coronal
access to the pulp chamber must provide a straight line
pathway into the canal orifice.
Modifications in access preparation may be required to
permit the instrument to penetrate, unimpeded, to the
apical constriction.


To achieve the highest degree of accuracy in working
length determination, a combination of several methods
should be used.

1.RADIOGRAPHIC METHOD.
2.DIGITAL TACTILE METHOD.
3.PAPER POINT EVALUATION
METHOD.
4.ELECTRONIC METHOD.
5.AVERAGE LENGTH METHOD

METHODS OF DETERMINING Radiographic Apex Location.
Materials and Conditions.
:1. Good, undistorted, preoperative radiographs showing
the total length and all roots of the involved tooth.
2. Adequate coronal access to all canals.
3. An endodontic millimeter ruler.
4. Working knowledge of the average length of all of the teeth.
5. A definite, repeatable plane of reference to an
anatomic landmark on the tooth, a fact that should
be noted on the patient’s record.

A.Do not use weakened enamel walls or diagonal lines of fracture
as a reference site for length-of-tooth measurement.
B,Weakened cusps or incisal edges are reduced to a well-
supported tooth structure.

DIAGNOSTIC
RADIOGRAPH


WEINE”S RECOMENDATIONS


PAPER POINT METHOD


ELECTRONIC METHOD

electrode APEX LOCATOR

Lip attachment


APEX LOCATORS
The scientific basis for apex locators originated with
research conducted by Suzuki in 1942.
PRINCIPLE
His in vivo research on dogs using direct current
discovered that the electrical resistance between the
periodontal ligament and the oral mucosa was a
constant value of 6.5 kilo-ohms.


All apex locators function by using the human body
to complete an electrical circuit. One side of the apex
locator’s circuitry is connected to an endodontic
instrument.
The other side is connected to the patient’s body,
either by a contact to the patient’s lip or by an
electrode held in the patient’s hand.


This classification is based on the type of current flow and
the opposition to the current flow, as well as the number of
frequencies involved.

First-Generation Apex Locators. First-generation
apex location devices, also known as resistance apex
locatorsmeasure 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 kilo-ohms
combination apex locator and pulp vitality tester.

Second-Generation Apex Locators. Second-generation
apex locators, also known as impedance apex locators,
measure opposition to the flow of alternating
current or impedance. Inoue developed the Sono-
Explorer, one of the earliest of the second-generation
apex locators.

Digipex, Exact-A- pex,foramatronIv


THIRD GENERATION

the impedances offered by the circuit to currents of
differing frequencies will change relative to each other.
This is the principle on which the operation of the
“third-generation” apex locators is based.


ROOT ZX


Working length in root canal treatment /certified fixed orthodontic courses by Indian dental academy

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Working length in root canal treatment /certified fixed orthodontic courses by Indian dental academy