Simplified anatomical Crown Down technique: demonstration (video) and protocol

This video demonstrates a variant of the crown down root canal treatment technique (from the crown down), called the simplified anatomic technique by the author. The technique was developed by Professor Andre Machado, Brazil; the performer is one of his students.

The technique involves the absence of pressure (pressureless) and is recommended for curved canals. According to the author of the video, one of the advantages of this technique is the successful combination of low cost of its use and high efficiency.

The technique includes five steps.

1. Pulp removal (with a “carpet path”).
2. Formation of the coronal and middle thirds.
3. Snapshot to determine the full working depth of the tool.
4. Formation of the apical third of the canal.
5. Final irrigation (not shown in this video).

The video shows all 27 steps and is almost 11 minutes long. If desired, you can “skip” a step when its essence becomes clear. Below is the protocol in text, and at the very end of the article is a short English-Russian glossary of terms used in the video. For those who want to improve their “dental English”.

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Pulp removal

1. Pulp removal. File No. 15 H, 16 mm, filling motion.
2. Irrigation.
3. Pulp removal. File No. 10 K 18 mm, reciprocating twisting movements (as when winding a watch), alternating with pulling.
4. Irrigation.
5. Pulp removal. File No. 10 K 20 mm, reciprocating twisting movements (as when winding a watch), alternating with pulling.
6. Irrigation.
7. Pulp removal. File No. 08 K 22 mm, reciprocating twisting movements (as when winding a watch), alternating with pulling.
8. Irrigation.
9. Pulp removal. File No. 06 K 24 mm, reciprocating twisting movements (as when winding a watch), alternating with pulling.
10. Irrigation.
11. "Carpet". File No. 08 K 24, vertical reciprocating movements (up and down)
12. "Carpet". File No. 10 K 24, reciprocating movements vertically (up and down)
13. Irrigation.
14. "Carpet". File No. 15 FF 24, reciprocating movements vertically (up and down).

Presentation on the topic: Methods of instrumental treatment of root canals (Step Back, Crown Down,

Baibulova K.K.candidate of medical sciences, associate professor

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Slide 2: Tasks of instrumental (mechanical) processing of channels:

cleaning the root canal (RC) from pulp residues or its decay, softened infected dentin, foreign particles (microorganisms, food debris, etc.)

);passing obliterated areas;expanding the canal, straightening the curvatures and giving a shape convenient for filling;smoothing the canal walls to improve the contact of medications with the infected surface of the parietal dentin and ensure a tight fit of the filling material

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Slide 5: Rules for performing instrumental processing (IO):

high-quality implementation of the stage is possible only if the preliminary stages are correctly completed: isolation from saliva, expansion of the mouths of the CC and formation of access, determination of the working length; AI is carried out with the obligatory preliminary introduction of preparations into the channels for lubrication and chemical expansion of the channels. This speeds up work and reduces the risk of tool jamming and breakage.

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Slide 8: Apical-coronal methods

Stage 1 - passing the CC: following the irrigation protocol, the CCs are passed to the physiological apex with thin K-reamers, for example size 10, or passfinders. The main technique for performing a root canal is rimming. The K-reamer is inserted into the root canal, turned a quarter or half turn, like winding a watch, then removed and cleaned.

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Slide 13: Step Back technique (“step back”)

Passing the CC to the physiological apex with a K-reamer or a small-size pathfinder to the working length using back-and-forth movements with careful irrigation; Repeating these actions without much resistance until the K-reamer No. 25 according to ISO or two sizes larger than the first reaches working length (for example 20 mm)

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Slide 18

Sealing the apical portion of the canal with dentine chips can lead to file straightening and even perforation

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Slide 19: Crown Down Technique

The coronal-apical “Crown-D own” technique involves the sequential use of endodontic instruments from larger to smaller sizes, starting from the mouth to the top of the CC. First of all, the primary passage of the CC is carried out to a working length of up to 20 instrument sizes according to ISO (carpet path).

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Slide 21: Advantages of the method:

Less risk of microflora and putrid masses being released into the periodontium; Reduced risk of instrument fracture in the canal, improved control over its progress; By following the irrigation protocol, maximum cleaning and disinfection of the root canal system can be achieved

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Slide 22: Crown Down technique modified for machine tools

Basic principles of operation: - progression from crown to apex; - sequence of use of instruments - from large to smaller sizes; - sequence of use of instruments - from larger taper to smaller

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Slide 23: Algorithm for canal preparation using the “Crown Down” technique with GTI files:

Rinse the canal mouth and the tooth cavity with sodium hypochlorite, using it as a reservoir for the drug; Go through the canal with a K-file of at least size 15 and determine the working length; Prepare the canal mouth with a 10/20 file at a speed of 300 rpm, moving slowly, without pressure file inside for 3-5 seconds;

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Slide 24: continuation

Change file to 08/20 to continue processing the canal in the middle third; Change file to 06/20 to continue preparation to the apical narrowing; Make the final determination of the working length.

If necessary, expand the apical part of the canal to the desired size - most often to 04/20.

There are other methods in which preparation is performed with instruments of the same taper, but of decreasing sizes.

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Slide 26: Balanced Strength Technique

After determining the working length of the canal and selecting the K-file by diameter, it is inserted into the canal until it stops.

Then, with little effort, the instrument is turned clockwise by 120-180 0 (no more than 1 turn!) and, pressing on the file in the apical direction to fix it at a given depth, it is turned 360 0 counterclockwise. It is important to press on the file so that it is not removed from the canal, but rotates at the same level.

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Slide 31: Quality criteria for instrumental treatment of root canals

Expansion of the canal to the working length Optimal conical shape along the entire length of the canal Preservation of the spatial topography of the canal lumen Countershape in the apical part of the canal Preservation of the size and location of the apical foramen.

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Formation of the apical third of the canal

1. Irrigation.
2. Formation of the apical third of the canal. File No. 35 FF, 20 mm, reciprocating twisting movements (as when winding a watch), alternating with pulling.
3. Irrigation. Passing the file 10 K, movements - as when removing pulp.
4. Formation of the apical third of the canal. File No. 30 FF, 22 mm, reciprocating twisting movements (as when winding a watch), alternating with pulling.
5. Irrigation. Passing the file 10 K, movements - as when removing pulp.
6. Formation of the apical third of the canal. File No. 25 FF, 24 mm (passing), reciprocating twisting movements (as when winding a watch), alternating with pulling.
7. Irrigation. Passing the file 10 K, movements - as when removing pulp.

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Techniques for Using Endodontic Instrumentation

This article is a continuation of the topic of endodontic instrumentation and methods of its use.

Determination of the working length of the root canal

Determining the working length of the root canal can be considered a key point in endodontic treatment. Being an integral stage, it does not take much time, however, it should not be neglected.

The working length can be defined as the distance between a conventional point on the tooth crown (for example, any preserved cusp), which we remember throughout the treatment, and the physiological apex.

There is a difference between certain types of constrictions in the apical third that must be remembered.

Physiological narrowing is the point of transition between endodont and periodontium; the walls of the canal in this place are made of cement.

Anatomical apex is the anatomical tip of the tooth root.

X-ray apex – image of the anatomical apex on the Rh-gram.

Methods for determining the working length of the canal include the use of an apex locator, X-ray, tactile, tabular, paper pins and the sensitivity method.

Apex locator

It is impossible to imagine modern endodontics without an apex locator. Its action is based on determining the location of the enamel-dentin border.

The hard tissues of the tooth and the mucous membrane have different resistance indicators (higher for hard tissues). When the instrument is inserted into the canal, the resistance on the metal part of the mouthpiece increases sharply.

An open electrical circuit is created. When the constriction is reached, the circuit closes.

Modern apex locators work equally well in dry or wet canals. The method has an accuracy of 90% or more, provided that the canal is not blocked by sawdust from infected dentin.

Tabular method for determining working length

The tabular method for determining the working length is based on the use of the average long-studied lengths of the root canals of each tooth. But no one has canceled the individual parameters of each person.

X-ray method

The radiographic method is suitable for filling the canal up to the radiographic apex. On the plus side, the method is objective; in most cases, it is easy to recognize the top with a correctly taken picture.

The disadvantages are that the structures may overlap each other in the image, there is a high probability of poor visualization of curved canals, difficulties in performing in some patients (increased gag reflex, radiation exposure).

Paper point method

The paper pin method is based on moistening the tip of the pin while bringing it to the top. It can be wetted with blood, serum, pus.

Tactile method

The tactile method is the determination of the working length of the canal based on one’s tactile sensations. The result depends on the doctor’s experience, since the technique is complex and is not effective if the apex is unformed.

The patient's pain can also help in determining the working length at the moment the instrument penetrates the apex and comes into contact with the tissues of the apical periodontium.

After determining the working length, preparation or mechanical treatment of the root canal begins. Today, many methods have been invented, each of them has a specific purpose, and also has advantages and disadvantages. To understand the specifics of creating a root canal shape and subsequent filling, you should start with the basic techniques.

Step back technique (step back)

The Step back technique is considered basic in the study of the art of endodontics. It, being the most popular, is easy to learn and perform.

Stage 1 – passage of the root canal and determination of its working length

Root canal passage is performed using K-reamers. After passing the canal to the apical foramen, the working length is established using a targeted Rh-gram with the instrument inserted into the root canal. The established working length is fixed with a stopper.

Stage 2 – formation of the apical stop

The purpose of this stage is to create an apical stop for the subsequent gutta-percha pin and endosealant to prevent protrusion beyond the apical foramen into the periodontal tissue.

We begin this stage by processing the root canal with a K-file of the same number, which managed to reach the apical foramen and with which we felt it jammed in the apex area. The instrument is inserted into the root canal and processed with sawing movements up and down. After this, the canal is washed with an antiseptic solution.

Next, use the tool of the next number with the same length set by the stopper. Mechanical and medicinal treatment of the canal is repeated. Use tools 3-4 numbers larger than the original (but not less than No. 25 - for adequate preparation and rinsing of the canal). The last tool is called Master file.

After these manipulations, the root canal acquires a conical shape, which corresponds to the taper of the instrumentation and standard gutta-percha pins.

Stage 3 – treatment of the apical third of the root canal

Continue processing the canal with the next instrument number, but reduce the length by 1 mm. The next tool will be 2 mm smaller, then 3 mm smaller, and so on. Between tools we return to the Master file each time to smooth out the steps in the apical third. Do not forget about antiseptic treatment of the channel between all instruments.

Stage 4 – formation of the middle and upper thirds of the root canal

The goal is to create a funnel-shaped canal mouth for subsequent adequate rinsing with an antiseptic and filling.

It is recommended to use Gates Glidden sequentially from number 1 to number 3. We use it in the straight part of the channel. This stage is completed by passing the Master file over the entire length of the channel.

Stage 5 – final alignment of the canal walls

To give the final conical shape to the canal, its walls are passed and smoothed using a Master file.

In addition to the apical-coronal methods, which include the standard technique (canal preparation with K-reamers from smaller to larger sizes) and the “step back” technique, there are coronal-apical methods, including Step Down and Crown Down.

The difference between them is that they first start with preparing the upper and middle third of the canal, then determine the working length and, at the very end, form the apical stop.

The advantage of coronal-apical methods is to simplify the antiseptic treatment of the canal, facilitate access to the apical third of the canal, prevent jamming of the instrument and the creation of a dentinal plug in the lower third of the canal, prevent the pushing of infected tissues beyond the apex, maintain the anatomical shape of the canal and there is no “loss of working length.” The disadvantage is the difficulty in determining the working length and patency of the root canal.

Step Down technique

Stage 1 – preliminary assessment of working length

The instrument is not inserted to the top. The radiograph determines the number of root canals, their curvature and estimated length.

Stage 2 – expansion of the mouth, formation of the upper and middle third of the canal, creating access to the apical third

A thin K-file (No. 8 or 10) is inserted into the root canal 4-5 mm or until the beginning of the curvature. Processing of this part of the canal begins with K or H-files, thus not reaching the apex. The stage is completed by using Gates Glidden from 1 to 3 numbers, inserting it into the canal only 1-2 mm.

Stage 3 – passing the apical part and determining the length of the root canal

They pass with a K-rimmer until it jams and determine the working length as in the “step back” technique.

Stage 4 – treatment of the apical third with an instrument and formation of the apical stop

The treatment is carried out in the same way as in the Step back technique. The channel takes the shape of a cone.

Stage 5 – final alignment of the walls

The final alignment is carried out with the same instrument used for processing the apical third of the canal.

Crown Down technique

The Crown Down technique is successfully used in case of significant infection of the root canal, to prevent the removal of dentinal filings beyond the apex, for comfortable medicinal treatment of the canal and in the treatment of periodontitis in children.

Stage 1 – insertion of K-file No. 35 to a depth of 16 mm.

If difficulties arise, the causes may be curvature of the root canal or its narrowing. If the cause is curvature, then we process part of the root canal until the curvature occurs. If the reason is narrowing, we take a smaller file and try to go 16 mm. The goal is to freely pass the K-file No. 35 to a length of 16 mm.

Stage 2 – determination of the “temporary” working length

On the Rh-gram we determine the intermediate working length with the instrument in the canal not brought to the apex by 3 mm.

Stage 3 – processing the canal to a “temporary” working length

Begin by introducing and scrolling K-file No. 35. Then file No. 30, No. 25, etc. until reaching working length.

Stage 4 – determining the final working length

As in stage 2, we use a photograph to determine the working length with the instrument inserted into the root canal.

Stage 5 – root canal expansion

The expansion of the canal is initially carried out with K-file No. 40, then No. 35, etc. until working length is reached. The instrument is inserted into the root canal, without pressure, rotated two turns clockwise and withdrawn. With each subsequent tool they try to move deeper, scrolling it clockwise.

After this, the cycle is repeated again, but starting with file No. 45. The next cycle is from file No. 50. Continue until the apical third is expanded to the desired size, but not less than No. 25.

In the next article we will get acquainted with the options for medical treatment of root canals. Their features, pros and cons of each antiseptic.

The article was written by O. Vishnyak specifically for the OHI-S.COM website. Please, when copying material, do not forget to provide a link to the current page.

Learning Dental English

Coronal third, middle third, apical third

– coronal third, middle third, apical third (tooth root).

Glide path

– “carpet path”, a processed section of the canal that makes it easier.

Working length

– working length (for example, endotool).

Mesiobuccal

– medial buccal (about the root); mesial - medial, buccal - buccal.

GG drill

– Gates-Glidden drill

Patency

– channel passage