A tooth root takes roughly 2 to 3 years to fully form after the tooth erupts through the gum. The exact timeline depends on which tooth it is, with some roots completing as early as age 9 and others not finishing until the late teens or even later. If you’re actually looking for how long a root canal procedure takes at the dentist, that’s a different question entirely, and we’ll cover that below too.
How Tooth Roots Develop
When a permanent tooth pushes through the gum, its root isn’t finished yet. The crown (the visible part) appears first, and the root continues growing downward into the jawbone over the next few years. During this time, the tip of the root remains open, gradually narrowing until it closes completely in a process called apical closure. Until that closure happens, the tooth is more vulnerable to damage and infection because the open root tip allows bacteria easier access to the nerve and blood supply inside.
Apical closure typically occurs about 3 years after a tooth erupts. So a first molar that comes in around age 6 will have a fully formed root by age 9 or 10, while a second molar erupting at 12 won’t have complete roots until around age 14 to 16.
Root Completion Ages by Tooth Type
According to the American Academy of Pediatric Dentistry, here’s when each permanent tooth’s root is typically finished:
- Central incisors: Erupt at 6 to 8, roots complete by 9 to 10
- Lateral incisors: Erupt at 7 to 9, roots complete by 10 to 11
- Canines: Erupt at 9 to 12, roots complete by 12 to 15
- First premolars: Erupt at 10 to 12, roots complete by 12 to 13
- Second premolars: Erupt at 10 to 13, roots complete by 12 to 14
- First molars: Erupt at 5.5 to 7, roots complete by 9 to 10
- Second molars: Erupt at 12 to 14, roots complete by 14 to 16
- Third molars (wisdom teeth): Erupt at 17 to 30, roots complete by 17 to 30
The front teeth tend to finish fastest, while canines and wisdom teeth have the widest range. Wisdom teeth are the most unpredictable. Their roots can still be forming well into a person’s twenties, which is one reason dentists sometimes recommend removing them before the roots fully develop, when extraction is simpler.
Why Incomplete Roots Matter
If a child or teenager injures a tooth before the root has finished forming, treatment looks different than it would for an adult with a fully mature tooth. A dentist may try to keep the root alive and encourage it to continue developing naturally, rather than performing a standard root canal that would remove the nerve. Preserving that living tissue gives the root the best chance of reaching its full length and thickness, which makes the tooth stronger long-term.
When the nerve has already died in a tooth with an open root tip, the dentist needs to stimulate the tip to close before sealing it. This can add months to the treatment process compared to working on a tooth with a fully closed root.
How Long a Root Canal Procedure Takes
If your question is about the dental procedure rather than biological development, a root canal typically takes between 30 minutes and 3 hours, depending on which tooth is being treated. The number of root canals inside the tooth is the biggest factor.
Front teeth (incisors and canines) have a single root canal, so treatment usually takes 45 minutes to an hour. Premolars have one or two canals and generally take about an hour. Molars are the most complex, with up to four canals. Just cleaning and filling those canals takes about an hour, so the full procedure on a molar often runs 90 minutes or more. None of these times include placing a crown afterward, which is usually done at a separate appointment.
Recovery After a Root Canal
Most people recover in less than a week. You can expect mild soreness and some pressure sensitivity in the days following the procedure, but sharp or worsening pain beyond that first week is not typical and worth a call to your dentist. The tooth itself no longer has a living nerve inside it, so the soreness you feel comes from the surrounding tissue settling down after the work.