This document discusses the shaping and cleaning of root canals. It defines root canal shaping as removing pulp tissues and debris from the canal while shaping it to receive obturation material. The objectives of root canal shaping are to create a continuously tapering, conical shape that is narrow apically and widest coronally. The document outlines the phases of root canal shaping including negotiation, coronal pre-enlargement, working length determination, and shaping techniques. It describes crown-down technique in detail, noting that it involves first instrumenting the coronal third before apical shaping to help remove debris and gauge the canal more accurately.
2. INTRODUCTION:
DEFINITIONS
Removing the pulp tissues and debris from the canal
and shaping the canal to receive an obturation material.
obturation of an improperly cleaned canal would still
lead to an endodontic failure irrespective of the
obturation.
OBJECTIVES
3. MECHANICAL OBJECTIVES:
1. CONTINUOUS TAPERING CONICAL SHAPE
2. NARROW APICALLY AND WIDEST
CORONALLY
3. CONCEPT OF FLOW (MULTIPLE PLANES)
4. APICAL FORAMEN AS NARROW AS
POSSIBLE
5. AVOID TRANSPORTATION OF APICAL
FORAMEN
4. BIOLOGICAL OBJECTIVES:
CONFINEMENT OF INSTRUMENT TO THE ROOTS
NECROTIC DEBRIS NOT FORCED PERIAPICALLY
COMPLETE REMOVAL OF TISSUE FROM THE
CANAL SPACE
CREATION OF SUFFICIENT SPACE FOR
OBTURATING MATERIAL
5. GOALS OF THE RADICULAR
SPACE
To eliminate microorganisms on
root canal
To completely remove pulp tissue
To increase the capacity of the
root canal to permit irrigation
solution to reach apical third
To shape root canal to receive
obturation material.
6. PRINCIPLES OF CANAL
INSTRUMENTATION
STRAIGHT LINE ACCESS
PRECURVING
RETAINING ITS ORIGINAL FORM & SHAPE
IRRIGATION
RESTRICTING INSTRUMENTS WITHIN THE CANAL
RECAPITULATION
REMOVAL OF DENTINAL DEBRIS
7. PHASES IN SHAPING OF ROOT CANAL
I. NEGOTIATION (PATENCY FILING)
II. CORONAL PRE-ENLARGEMENT
III. WORKING LENGTH DETERMINATION
IV. SHAPING TECHNIQUES
V. WORKING WIDTH
8. PATENCY FILING
the concept of creating a path up to the working
length without altering the original root canal
anatomy.
It is usually performed with a size 10 or smaller k file
which used in reaming motion.
9. CORONAL PRE-ENLARGEMENT
Concept of enlarging the coronal third of the root
canal prior to the estimation of working length.
Working length of the tooth should determined only
after coronal pre-enlargement of the canal is
completed.
Coronal pre-enlargement achieved with orifice
enlargers or gates glidden drills.
ADVANTAGES
Prevents premature binding of the shaping
instruments to the canal walls.
Removes coronal third debris before apical third
shaping
Allow operator to gauge the apical third of the
canal more accurately.
10. WORKING LENGTH
DETERMINATIOIN
It defined as the distance from a coronal
reference point to the point at which the
canal preparation and Obturation should
terminate.
Canal preparation is clinically
recommended to terminates
instrumentation and Obturation within
0.5mm to 1.0mm short of radiographic
apex.
11. ROOT CANAL SHAPING TECHNIQUES
The endodontic hand instrument can be employed in any one of the
techniques such as
STEP BACK TECHNIQUE CROWN DOWN TECHNIQUE
HYBRID TECHNIQUE
13. patency of canal achieved with a size 8 or 10 k file
preparation of coronal two third of the canal using H-files size of 15,20,and 25 to
a working length of 16-18mm or to point where files starting
flaring the coronal segment of canal with GG drills Nos.2 and 3
apical instrumentation with a small size of 10 ,15 K file followed by working
length determination
placement of large file(K-file 60) to point of canal binding
process repeated with smaller files until working length is reached
Apical portion of canal is enlarged to the approriate master apical file size. final
canal taper is accomplished by master apical file
14. ADVANTAGES
Easier than step back technique
Removal of coronal obstructions allows removal of
bulk of tissues , debris ,microbes before apical
shaping.
Minimizes extrusion of debris through apical
foramen
Better access and control over apical enlarging
instrument
Allows penetration of irrigants .
Working length less likely to be change.