1. The state of the pulp before root canal treatment
The state of the pulp before root canal treatment is a controversial factor. It is generally believed that the success rate of root canal treatment of vital pulp is higher than that of dead pulp.
2. The state of the root apex before root canal treatment
Apical lesions before root canal treatment will reduce the success rate of root canal treatment by 7.5% to 14%. However, whether the size of apical lesions affects the long-term effect of root canal treatment is still controversial.
3. The root canal preparation methods and filling techniques of root canal treatment
There is no significant difference in the effect of different preparation methods on the success rate of root canal treatment; the case of cold side pressure filling has a higher success rate than that of pressure filling without side, and the success rate of full-length root canal filling is higher than that of root canal filling alone, but there is no different statistical significance. The size of the main file for root canal preparation has no significant effect on the long-term effect of root canal treatment.
4. The root canal filling materials of root canal treatment
The combination of gutta-percha points and root canal sealer is the most commonly used clinical method. Simply using root canal sealer, or combining silver needle with sealer for root canal will have more problems and is not a good method.
5. The filling quality of apical area in root canal treatment
It is divided into two factors: the filling position and the filling density of the apical area. It is acceptable for root canal fillings to be within 0～2mm from the X-ray root tip position. Under-filling or overfilling will reduce the effect of root canal treatment. In addition, the non-compactable filling of the apical area will significantly reduce the long-term effect of root canal treatment for it leaves room for microorganisms to survive; while the root tip side branches have more root canals, and the tissue fluid is easy to infiltrate when the root tip is not densely filled, which will provide nutrition for the bacteria, ultimately leading to the failure of root canal treatment.
6. The condition of crown restoration after root canal treatment
Crown restoration should be a necessary step for a perfect root canal treatment. If the crown restoration is not done well, it will affect the long-term effect of root canal treatment.
7. Accidents in root canal treatment
Side penetration and broken instruments in root canal treatment have a certain impact on the effect. It is mainly because it is difficult to prepare, rinse and fill the root canal under side penetration or broken instruments, which leads to an increase in the failure rate of root canal treatment; but with the application of root canal microscope, ultrasound and excellent repair materials (such as MTA), accidents in root canal treatment are treated in time, which improves the long-term curative effect.