Introduction

“Your cavity is severe, so we’ll need to remove the nerve.”

Many patients who receive this explanation and undergo treatment assume, “Since the nerve is gone, that tooth shouldn’t hurt anymore.”

However, in reality, it’s not uncommon for people to suffer from the symptom of tooth pain despite having the nerve removed.

From the practitioner’s perspective, this is by no means rare. In fact, it could be called a “common occurrence.” Yet for patients, it’s an unexpected event that often leads to anxiety and distrust.

This article will explain in detail:

• The causes of persistent pain after nerve removal
• Differences in the quality of root canal treatment
• The proper approach to treatment.

Why does pain persist after a root canal?

The treatment for a tooth that has had its nerve removed is called “root canal therapy.” Its purpose is to thoroughly clean and disinfect the canal inside the tooth where nerves and blood vessels pass, eliminating bacterial infection.

However, this treatment demands extreme precision. In the following situations, pain can persist:

• Contaminants or infection sources remain inside the root canal
• Infection has progressed to areas too fine to see
• The tooth itself is cracked or has a hole
• Cavities have progressed to the bone
• Treatment was performed without using appropriate instruments or equipment

In other words, “removing the nerve ≠ guaranteed complete pain relief”.

A common real-life case

A patient who visited our clinic recently was suffering from persistent pain despite having a nerve removal procedure done at another clinic.

Upon detailed examination, we found the treatment lacked: 

Rubber dam isolation

Microscope use

• CT imaging

These critical steps were absent.

When we examined the tooth internally under our microscope, residual contamination was evident. With such conditions, recovery is impossible. Patients often feel, “I’ve been coming back for disinfection multiple times, but it’s not getting better,” and this is frequently due to such deficiencies in treatment precision.

Differences in treatment precision are a major factor

Root canal treatment is a field within dentistry that requires particularly delicate work.

Despite this, under Japan’s insurance-based system, procedures are often performed “quickly and cheaply,” resulting in significant variations in quality.

For example:

• Rubber dam isolation: Prevents saliva and bacteria from entering, significantly increasing treatment success rates.
• Microscope (dental microscope): Allows observation of details invisible to the naked eye.
• CT imaging: Provides three-dimensional visualization of root morphology and the extent of lesions.

Without all these tools, complete infection removal is difficult.

Even if the tooth is cracked or has a hole

The cause of pain isn’t always just “low treatment precision.”

Sometimes the tooth itself is already fractured, or cavities have created holes inside the tooth reaching the bone. Alternatively, cracks (fissures) may develop in the tooth during treatment, allowing bacteria to invade.

In such cases, root canal treatment alone may be insufficient, necessitating extraction or restorative treatment (such as bridges or implants).

Repeated disinfection alone won’t cure it

Some patients report having “root disinfection repeated many times.” However, in reality, even dozens of disinfection sessions often fail to achieve healing.

What matters is **not the “number of times” but the “quality”**.

Even with a single treatment, if infection is reliably removed under rubber dam isolation using a microscope, there’s no need for unnecessary, repeated visits.

At our clinic, we have performed root canal treatments using rubber dam isolation and microscopes within the scope of insurance-covered treatments for the past 10 years. We have never had a patient require endless disinfection appointments. This proves that “accurately removing the source of infection” is paramount.

How to make a tooth with a removed nerve last longer

A tooth with its nerve removed tends to become brittle because its nutrient supply is cut off. Therefore, post-treatment management is extremely important.

• Prevent infection with proper root canal filling
• Reinforce the tooth with a crown or similar restoration
• Monitor its condition through regular check-ups
• Manage bite alignment and lifestyle habits

It’s not “treatment ends when the procedure is done”; post-treatment maintenance significantly impacts the tooth’s lifespan.

Summary

“My tooth hurts even though the nerve was removed” is a serious concern for patients.

However, most cases stem from:

• Inadequate root canal treatment precision (no rubber dam, microscope, or CT scan)
• Tooth fracture or advancing decay
• Repeated improper treatments

With the right treatment environment and techniques, improvement is possible without needing multiple disinfection visits.

If you’re experiencing persistent pain despite having had a root canal, we recommend considering a precise examination and retreatment using a microscope.

The most crucial step for patients is “accurately identifying the cause.”

The longer you wait, the harder it becomes to save the tooth. Please consult us.