is also known as Telescopic canal preparation or serial root canal preparation.

Step back technique emphasizes keeping the apical preparation small

and producing a gradual taper coronally

This technique was first described in 1960 by Mullaney

basically this technique involves the

the canal preparation into two phases

phase I involves the preparation of apical constriction

and phase II involves the preparation of the remaining canal

Phase I

Evaluate the carious tooth before initiating endodontic treatment

prepare the access cavity, and locate the canal orifices

Establish the working length of the tooth using pathfinder

The working length is the distance between the reference point coronally and the anatomical apex

two ways to determine the working length

first by x ray that taken while the file is inserted in the canal

In this situation Apical foramen is usually found 0.5-1mm

shorter from the radiographic apex

so we need to decrease the length

Second by Electronic apex locators

That designed to determine the canal length by

giving the reading when the file tip is at the apical foramen

first lubricate the instrument for use in apical area

by EDTA or other lubricant

Now insert the first K file into the canal

with considering the working length with gentle

clockwise and anticlockwise rotation

of file with minimal apical pressure is given

Remove the instrument and irrigate the canal

Place the next larger size files to

to the working length in similar manner and again irrigate the canal

Don't forget to recapitulate the canal with

previous similar number of H file

This breaks up apical debris

which are washed away with the irrigant

Repeat the process until a size 25

or 30 H-file that reaches the working length

that will be the master file or

Recapitulate between the files by

placing it into the working length

Phase II

Place next file in the series to a length 1 mm short of working length

remove it , irrigate and recapitulate

Repeat the same procedure with successively larger files

at 1 mm more shorter from the previously used file

Finally, refining of the root canal is

done by master apical file with

push-pull strokes to achieve a smooth taper form of the root canal

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