STEP DOWN/ CROWN DOWN PRESSURELESS TECHNIQUE
In this technique Gates- Glidden drills and larger size files
are first used in the coronal 2/3rds of the root canal and
progressively smaller files are used until the desired
working length is achieved.
Main disadvantage of Step Back technique was extrusion
of debris apically. This was prevented by this technique.
This technique provides a coronal escapeway that reduces
the piston in a cylinder effect responsible for the
extrusion from the apex.
The canal is explored with a small instrument to assess
patency and morphology
Working length established
The coronal third is flared with a Gates-glidden drill #2 or
#3 [depending upon the initial anatomy of the root canal]
A large file is introduced into the canal till resistance is
felt [ using a watch winding motion] example size #35
Now a smaller file [#30] is introduced into the canal to a
depth greater than the initial file, till a resistance is felt.
Sequentially smaller files are introduced until the apical
portion is reached
throughout these steps.
Final smoothening of the walls is accomplished with a a
headstorm file [a size larger than the master file] used
Clinical benefits of Crown-Down technique
1. Ease of removal of obstacles that prevent access to the
2. Enhanced tactile feed back with all instruments by
removal of coronal interferences.
3. Increased space for Irrigant penetration and debridement
4. Rapid removal of dental pulpal tissue that is located in
the coronal 1/3rd.
5. Straight line access to root curves and canal junctions.
6. Decrease in canal blockages
Biological benefits of the Crown-Down technique
1. Rapid removal of contaminated, infected tissue from the
root canal system.
2. Removal of tissue debris coronally, thereby minimizing the
pushing of debris apically.
3. Enhanced disinfection of canal irregularities due to
increased irrigant penetration
PASSIVE STEP BACK TECHNIQUE
A modification of the step back technique
After determination of the apical diameter [example #30],
next higher file [#35] is inserted until it makes contact
It is the rotated a half turn and withdrawn
The process is repeated with larger and larger instruments.
#35 → #40 → #45 → #50 → …..
The entire sequence is then repeated .
Each time the instrument goes deeper than the previous
This creates a tapered preparation.
The canal morphology dictates the preparation shape.
Does not require a standardized measurement of
incremental step back.
Removal of debris and minor obstructions
Gradual and passive enlargement of the canal in apical to
ANTI CURVATURE FILING
•Advocated during the coronal flaring of canals to prevent
•The walls on the opposite side from the curve are
instrumented more than the inner walls resulting in a
decrease of the overall degree of canal curvature.
•Anti curvature approach can preserve dentinal thickness
near the furcation
•It also gives a more straight line access deeper into the
BALANCED FORCE TECHNIQUE [ROANES TECHNIQUE]
Based on the fact that the canal walls guide the instruments
An instrument normally cuts in both clock wise and counter
clock wise motion.
Technique consists of placing the instrument as apically as it
can go and then rotating it clockwise [ less than 180
motion engages the dentin
This is followed by a counter clockwise rotation [of at least
120 0 ] with slight apical pressure to break the engaged
dentin and enlarge the canal.
Small instruments --------- apical pressure is less
The clock wise rotation pulls the file apically while counter
clock wise motion pulls it coronally.
There fore chances of the file getting screwed apically during
the counter clock wise position is less.
This is repeated till the desired working length is obtained
Technique is carried out with modified K-files like
B. MODIFIED K-FILE
NICKEL TITANIUM [NiTi] ROTARY PREPARATION
These instruments utilize the CROWN DOWN [STEP DOWN]
Instruments of various tapers.
Coronal third → 0.10/ 0.08
Middle third →
Apical third →
FINAL APICAL ENLARGEMENT
AND APICAL CLEARING
The canals are enlarged to a minimum of three sizes more
than the first file that binds at the apex at full working
length [ initial apical file (IAF) ].
The last file used for the preparation at the apex is called
the Master Apical File [MAF].
After the MAF is reached the apex is cleared of all the
debris by using the master file at the working length in a
reaming action in the presence of an irrigant
Performed inbetween each successive enlarging file
irrespective of the technique used.
Involves the use of a small file to the whole working length.
This helps in clearing the apical portion and removing the
debris which gets collected there.
2.Working length determination
3.Straight line access [enlarging the coronal third]
4.Initial apical file determination
5.Rotary preparation on the middle third of the root
6.Apical step back preparation
7.Apical clearing and establishing a MAF
normal anatomic foramen to a new
Occurs mainly due to failing to precurve files, using large instruments.
When the instrument is overused - the elastic memory of the instrument may
create the teardrop and tearing of the apical foramen
another form of external transportation is direct perforation.
begins with a ledge or apical blockage.
continues its misdirection until it perforates the root surface.
– forcing uncurved instrument in a curved canal.
– Rapid advancement in file size.
• Identified by Loss of tactile sensation on instrument - loose feeling instead of
binding at the apex.