How Long Does It Take for a Cavity to Turn into a Root Canal?

You feel a little sting when sipping something cold. Maybe it’s nothing—just sensitivity, right? But what if that tiny twinge is your tooth’s way of waving a red flag? One of the most common dental questions is: How long does it take for a cavity to turn into a root canal? The answer might surprise you—and it might even save your tooth.

Let’s break it down.

From Cavity to Root Canal: What’s the Connection?

A cavity starts small. It’s actually a tiny hole in your tooth that occurs because acid-producing bacteria snack on starch and sugar. At first, it only feeds on the outside enamel, painlessly. But if left alone, it begins to burrow deeper into the tooth structure—straight for the nerve in the middle.

Once it moves into the pulp (the nerve- and blood-vessel containing soft tissue), infection is possible. That’s when a root canal is necessary—not to produce pain, but to remove it and preserve the tooth.

The Phases of Decay: Understanding the Timeline

Cavities don’t skip stages—they move through them. Here’s what usually happens:

1. Enamel Decay

This is the first phase. The tooth’s enamel layer begins to deteriorate. You likely won’t notice anything yet.

2. Dentin Decay

Once the cavity reaches into the enamel and into the dentin below, you may start to feel sensitivity—especially to hot, cold, or sweet foods.

3. Pulp Damage

Here is where things become severe. The cavity reaches the pulp, and with it comes pain, inflammation, and even infection.

4. Abscess and Infection

If the infection spreads from beyond the tooth into surrounding tissues, an abscess can form—a cause of swelling, severe pain, and potentially fever.

How Fast Does It Happen?

This is the reality: it varies. There’s no specific ticking clock after a cavity has appeared, but this is a sense of it:

• With poor oral habits and high sugar, a cavity can penetrate root-canal territory in 3 to 6 months.
• With a person who has good habits and fluoride protection, it might take a year or so.
• In teenagers and children (with softer enamel), it occurs faster than in adults.

What’s alarming is how quietly cavities progress. By the time you experience significant pain, the damage is often deep—and costly.

Don’t Get It Confused With Something Else, Like Gum Disease

Many people tend to ignore the following: tooth pain isn’t always a cavity. Sometimes, what seems to be a cavity can actually be a sign of gum disease.

Gum problems have the following symptoms:

• Bleeding gums while brushing
• Constant bad breath
• Gum recession or loose teeth
• Swelling or tenderness of the gums

Left undiagnosed, gum disease can also result in tooth loss and infection—just as undiagnosed cavities can. The moral? Don’t play with dental signs and symptoms. Let your dentist diagnose it before it gets worse.

Red Flags That a Root Canal Might Be Necessary

If you notice any of the following, it might already be too late for an easy filling:

• Severe or aching tooth pain
• Persistent sensitivity to hot or cold
• Swelling or pus near the gumline
• A darkening or gray tint in one tooth
• Pain when chewing or touching the tooth

Once you’re at this stage, a root canal is often the only option to save your natural tooth.

So, how long does a cavity take to become a root canal? A couple of months to a couple of years—depending on your life and how fast you are. But this is certain: the longer you put it off, the worse it gets.

The good news? Early cavities are quick and inexpensive to fix. So if it’s been a while since your last checkup—or if you’ve got that “something’s not right” feeling in your mouth—don’t wait.