When teeth nerves lead to acute or chronic inflammation, or even necrosis of pulp tissue due to dental trauma, fracture, or severe tooth decay, it will result in apical bone lesions. The patient may feel pain or grow pustules, and need root canal treatment. The treatment involves removing infected pulp from the pulp chamber and root canals for root canal wall debridement and expansion. Finally, the root canal needs to be completely filled to avoid reinfection. It requires multiple appointments to complete the steps of root canal treatment. The appointment methods and times of treatment are to be decided after assessment by the physician. An observation period is needed after treatment. There may even be follow-up treatment even after symptoms disappear. 
Currently, large domestic hospitals and clinics employ “microscopic root canal treatment” that utilize the zoom function of dental microscopes. With ultrasound equipment, it mends the blind spot inside the canal that is not able to be seen by traditional root canal therapy. This can overcome most difficult cases, increasing the success rate of treatment.