The nemesis of pulp disease and periapical periodontitis - root canal therapy

Author: Huang Dingming, Chief Physician, West China Hospital of Stomatology, Sichuan University

Member of the Professional Committee of Endodontics of the Chinese Stomatological Association

Reviewer: Hou Benxiang, Chief Physician, Beijing Stomatological Hospital, Capital Medical University

Deputy Secretary General of the Chinese Stomatological Association

Pulp and periapical diseases are common oral infectious diseases mainly caused by bacteria. Therefore, eliminating and controlling the infecting bacterial microorganisms is the most basic principle of treatment.

At present, root canal therapy is one of the effective methods for treating pulp and periapical periodontitis, and is also the preferred treatment method in clinical practice.

Root canal therapy is a treatment method that uses physical and mechanical methods and chemical sterilization methods to remove infections within the root canal system, including bacteria, fungi, residual diseased pulp, and metabolic products of bacteria and other pathogenic microorganisms, thereby healing the lesions of the periapical tissues of teeth with pulp and periapical diseases and preventing re-infection of the periapical tissues.

1. How is root canal treatment performed for pulp and periapical periodontitis in adults?

Root canal treatment consists of four steps:

The first step is to open the pulp.

Pulp access is the process of creating a channel into the pulp cavity, which often requires drilling a hole in the occlusal surface of the tooth. This allows instruments, materials, and drugs to reach the entire root canal system smoothly during root canal treatment, thereby completely removing the microorganisms and infected tissues in the root canal system.

Therefore, some people describe the pulp opening of root canal treatment as the door to enter a house. If the door is not opened, people cannot enter the room. Similarly, root canal treatment cannot be performed without pulp opening of the diseased tooth.

Figure 1 Original copyright image, no permission to reprint

The second step is root canal preparation.

After the pulp is opened, instruments and drugs can be used to clean the root canal. Mechanically driven nickel-titanium files are mainly used to remove the infection on the surface of the root canal and the root canal wall, and to shape the root canal.

Due to the complexity of root canal anatomy, simple instrument cleaning is usually unable to completely remove the infection in the root canal system. Therefore, it is necessary to use root canal flushing fluid and other drugs to perform chemical cleaning of the root canal during the cleaning process, so as to completely flush out the remaining bacteria and infection in the root canal and achieve a sterile state in the root canal.

Figure 2 Original copyright image, no permission to reprint

The third step is root canal disinfection.

Although physical cleaning with instruments or chemical cleaning with flushing fluids are used during the root canal preparation process, due to the complexity of the root canal system, there are fine structures such as lateral root canals, root canal isthmuses, and apical divergences, and the above methods cannot guarantee complete cleaning of bacteria. At this time, it is necessary to seal some chemical drugs in the root canal system, such as calcium hydroxide, chlorhexidine, etc., to kill the remaining bacteria.

Figure 3 Original copyright image, no permission to reprint

The fourth step is root canal filling.

The main purpose of root canal filling is, on the one hand, to bury the remaining infected substances and bacteria in the root canal; on the other hand, to fill the entire root canal system tightly, filling the root canal apical foramen and lateral root canals. In this way, the remaining microorganisms in the root canal or the microorganisms in the oral cavity will not reach the periapical area, thus preventing the occurrence of periapical diseases.

Figure 4 Original copyright image, no permission to reprint

In summary, root canal treatment mainly includes four steps: pulp opening, root canal preparation, root canal disinfection and root canal filling.

2. What factors will affect the success rate of root canal treatment?

The success rate of root canal treatment can vary depending on the situation.

Some literature reports the success rate to be about 60 to 70 percent, while others report the success rate to be as high as 80 to 90 percent. It mainly depends on the condition of the affected teeth and the doctor's diagnosis and treatment level.

The first is the infection of the tooth itself.

If it is only early pulpitis, the infection is limited to the pulp of the crown of the affected tooth, and the bacteria have not yet entered the root canal, the doctor can achieve a good success rate of treatment as long as he pays attention to not causing infection in the root canal during the operation. According to foreign literature reports, the success rate of root canal treatment in this case can be as high as 94% two years after surgery.

If the bacteria have entered the root canal system but have not adhered to the root canal wall, and have not entered the dentinal tubules or lateral canals or apical bifurcations, a good result can be obtained after treatment.

If the bacteria have entered the dentinal tubules, lateral root canals, apical bifurcations and periapical areas, then the doctor's operating skills and treatment equipment requirements will be higher, and the treatment effect may be slightly inferior to the first two situations.

The purpose of root canal treatment is to control and eliminate the infection of the root canal system and keep the root canal in a sterile state. Therefore, if there are residual bacteria in the root canal, these residual bacteria may reach the periapical tissue through the apical foramen of the root canal system, causing re-infection of the periapical tissue, thus leading to the failure of root canal treatment.

Therefore, the success of root canal treatment depends on whether the infection in the root canal system is effectively controlled and managed.

Patients should achieve early detection and early treatment, and see a doctor for standardized root canal treatment as soon as possible, so as to ensure good treatment results and a higher success rate.

In addition to the infection of the tooth, the anatomical condition of the tooth itself also affects the success rate of root canal treatment.

If the root canal of the affected tooth is not complicated, the infection can generally be well controlled and satisfactory treatment results can be achieved.

If the root of the affected tooth is crooked, the root canal is calcified and small, and there are some lateral root canals and apical divergences, then the doctor's treatment technology and medical equipment are more demanding. Especially when bacteria enter these parts of the lateral root canal and apical divergence, even with the use of modern root canal treatment technology, the treatment effect is sometimes unsatisfactory.

3. What are the commonly used materials for root canal filling?

As mentioned above, through root canal preparation, the root canal system forms a relatively good shape. However, due to the complexity of the root canal system, irregular places such as lateral root canals and root canal isthmuses, materials with very good fluidity are required for root canal filling.

Therefore, the materials used for root canal filling in clinical practice include not only the main material gutta-percha tip, but also root canal filling paste. The main root canal is mainly sealed and filled with gutta-percha tip, while those smaller structures, such as lateral root canals and the isthmus of the root canal, need to be filled and sealed with the help of the fluidity of the root canal filling paste.

The main forming material in clinical practice is gutta-percha. When choosing gutta-percha, the main consideration is whether the shape, size, and taper of the gutta-percha tip match the shape of the prepared root canal. At the same time, when choosing a root canal filling paste, it is best to choose a material with good fluidity, antibacterial effect, and small solidification shrinkage, so that the root canal system can be effectively sealed.