Coronal-apical methods Step Down, Crown Down for root canal treatment

The development of dentistry today makes it possible to carry out many complex operations and preserve the teeth of patients even with advanced problems.

Most of the procedures require additional equipment, but the main thing is the skill of the dentist.

Coronary apical methods are one of the first to be studied in the course of dentistry.

The essence of technology

Coronal-apical methods are used to make the root canal of the tooth wide and accessible in the direction of the apical foramen using instruments with different dimensions.

In this case, the base of the root canal and the intermediate third are initially processed, after which the working length is estimated and work begins with the inner zone.

The length of the working surface is not calculated at the beginning of the intervention, but after the complete provision of access to the last third of the dental canal, smoothly reducing the size of the devices used. This method is considered to be more gentle and effective, but also more laborious, since the specialist has to each time determine the length of the tubule and calculate the instrument in accordance with the already made holes.

Modern methods of root canal treatment. Video:

Advantages

The active use of this group of methods is explained by a number of their advantages:

• providing excellent access to the deep part;
• reducing the possibility of tissue damage by infection inside the tooth due to the gradual elimination of the damaged material;
• facilitating drug treatment;
• reducing the risk of the tool getting stuck in the internal structure of the tooth;
• reducing the risk of blockage of deep parts by dentin sawdust and soft tissues;
• the ability not to reduce the "working length" of development;
• preservation of the natural shape of the channels.

The technique also has disadvantages associated with the inability to immediately determine the entire length of the channel and the degree of its patency. As a result, the technician has to spend a lot of time and effort in processing the root canal, especially when compared to apical-coronary root canal methods.

Indications

The described group of methods is recommended for use when:

• a high level of infection of structures, which may threaten the ingress of decaying pulp for the top;
• removal of the filling in the root canals;
• application of automated nickel-titanium profiles or GT files.

Step Down Technology

The "Step Down" technology assumes the creation of a cone-shaped working channel, which is most successful for working with apical constriction and filling of lumens.

Its technique includes the following stages:

1. Establishment of the working length of the processed canal. It is carried out using a diagnostic X-ray with the absence of instruments; the image can be used to determine the number and length of the root canals, as well as the level of their curvature.
2. Increase in the size of the mouth. It is processed using K-files of various sizes. At the beginning of the procedure, K-files No. 8 and No. 10 are used, depending on the size of the damage. They penetrate almost the entire depth, not reaching 4-5 millimeters to the end of the hole or to the place of its curvature. Expansion is done manually using H-files or K-files, starting with a thinner tool and moving towards a larger one. Standard set: # 15, then # 20, # 25, # 30 and so on. At the same time, the hole diameter gradually expands and becomes more accessible for processing. The extension does not reach the apical canal for about 5 millimeters. After that, machine technology comes into play, with which the mouth is formed with the help of Gates Glidden burs. It also follows the principle of a smooth transition from smaller to larger.
3. Finding the working length of the dental tubule. To begin with, it is passed by a passfinder or K-reamer along the entire length. Then a measuring X-ray is taken again, showing the length of the canal made and the degree of its expansion.
4. Cleaning the apical zone, using the Step-back technique with a sequential reduction of its size to the minimum - No. 25. The lower part of the opening becomes a cone shape, which has an apical stop in the region of the natural apex.
5. If the working surface is easily reached, it is not recommended to use a filing motion. In this case, the movement of the main apical file must be repeated many times until a full lumen is achieved. This will prevent blockage. A smooth transition at the border of the inner and intermediate third of the hole will provide good permeability and easy filling of the tooth with full penetration of particles into the canals. Otherwise, voids may appear, which in the future will lead to reprocessing of the tooth.

The use of this technique allows you to qualitatively clean and expand the root canal. The technology uses nickel-titanium profiles with high strength and chemical durability, due to which they make it possible to form a smooth root canal without chipping and steps. The likelihood of complications in this technique is extremely small, since all affected particles are removed immediately and cannot get deeper into the lumen.

Crown Down Technology

This technique involves moving towards the gum from the crown, when the size of the instruments gradually decreases, and the contents of the dental roots are removed in parts. The same applies to parietal dentin, which is removed using thin parts of the instrument, preventing the possibility of fracture or wedging of the instrument.

The Crown Down technique is used in situations where it is necessary to make the opening of the mouth funnel-shaped, it is more often used on difficult streamers, as well as for the purpose of treatment exacerbation of chronic apical periodontitis, in which infection has occurred, which must be limited by preventing the pushing of the affected tissues beyond the apical hole.

It allows you to maintain the natural shape of the canal and its direction without damaging healthy tissues.

Endodontics. Crown-Down technique in 3 minutes. Video:

In this technique, tools can be used:

• Gates Glidden;
• Profile Series 04;
• K -File;
• GT-Rotary.

The first method includes the steps:

• finding the mouth of the duct using K-File or Pathfinder;
• widening the passage with Gates Glidden # 5 and # 6;
• advance a couple of millimeters below the mouth with the same tool, but # 4;
• advancing another 2 millimeters beyond Gates Glidden # 3;
• implementation of Gates Glidden # 2 to manipulate a channel half of two-thirds of its length;
• use of x-rays to detect the working length of the lumen;
• manipulation with the apical zone of files manually.

The Crown Down technique, which uses Profiles, is carried out in a similar way:

• the mouth of the root canal is detected using Pathfinder, K-File;
• the wellhead is expanded to a larger size using Profile # 40;
• the length of the hole is determined, suitable for work and the initial file, which should be 2-3 numbers smaller than the original profile, it penetrates up to half the length holes;
• the channel is finished with a profile larger for expansion;
• the middle third of the bend is prepared for further manipulations using a profile having a diameter less than the first by a length of up to three quarters;
• the inside of the hole is cleaned with an even smaller profile;
• the last 1-2 millimeters of the pass are processed manually.

Due to the laboriousness of the Crown method, it is used with the use of machine tools, which somewhat facilitate the work of the dentist. At the same time, the passage expands to such an extent that it becomes available for treatment with medicines and high-quality filling.

At the same time, there is a risk of excessive expansion and a decrease in the mechanical strength of the tooth tissues. A specialist should determine the immersion level of the instrument; X-ray techniques can help him with this.

The use of modern technologies for processing dental canals allows you to prolong the life of your teeth and preserve their integrity. Timely visits to the dentist help to monitor the condition of the oral cavity and take timely measures to prevent deep penetration of the infection into the roots.