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Standartized technique Step-back technique

Modern techniques of instrumentation of root canals

1. Standardized technique

2. Step-back

3. Crown-down

Standardized technique – technique that is used in temporary and unformed permanent teeth. It is based on simple widening of root canal (aim - removal of infected predentin) with few instruments with the same working length without formation of tapered shape of root canals, because temporary and unformed permanent teeth have very thin walls.

Standartized technique Step-back technique

(cylindrical shape of root canal) (tapered shape of root canal)

!!!!!!!!!!!!!!!! Standardized technique can be performed with different instruments. In children’s deciduous and unformed permanent teeth they are H-files, because they have best cutting ability and can easy remove infected predentin. H-files are used in “filing” regimen. !!!!!!!!!!!!!!!!!!!!!!

Standardized method also can be used in narrow calcified root canals. In this case we use K-reamers in “reaming” regimen. This case in children is very rare.

Step-back technique -widening of the root canal from the apex to the root canal orifice with the instruments (K-files, H-files) that increase in size. As a result we have tapered shape of root canal.

This technique can be used in formed permanent straight or slightly curved root canals.

1 stage – passing of root canal (RC) for working length (WL) with K-file №8 or №10.

2 stage – formation of apical stopper at the level of apical constriction. We start with file that passed RC for WL (for example №10) and perform «watch-winding» motion (90° clockwise and counterclockwise). Then we use larger file (№15) and perform the same operations. Then again file №10 to avoid blocking of the root canal with dentin cuttings (recapitulation). We must enlarge apical part with 3-4 instruments to at least file №25 (for proper irrigation and obturation), so we use files: 10 – 15 – 10 – 20 – 15 – 25 – 20. If initial file is larger than №25, we enlarge root canal for 1-2 instruments. The last file that formed apical stopper is Master-file.

3 stage – formation of the apical, middle and coronal part of root canal. We take file №30 which WL will be for 1 mm lesser than previous instruments had. Than recapitulation with file №25 to full WL, then file №35 with WL - 2mm, recapitulation with file №25 to full WL, then file №40 with WL - 3mm and so on (30 – 25 – 35 – 25 – 40 – 25…). Depending on root canal anatomy WL can be shortened for 0,5mm, 1mm, 1,5mm, 2mm. For preparation of coronal part can be used Gates-Glidden burs.

4 stage – smoothing of root canal walls with H-file for 1 size lesser than Master-file (for example №20) in “filing”-regimen.