Tooth Anatomy
A tooth has four layered structures (enamel, dentin, pulp, cementum), one or more roots, and inside each root one or more canals carrying the pulp tissue. Endodontic outcomes depend on getting the canal anatomy exactly right — which is why every case at Hope Endodontics uses a surgical operating microscope and CBCT 3D imaging.
Medically reviewed by Dr. Hope Feldman · Diplomate, American Board of Endodontics
Last reviewed May 5, 2026 · NPI 1275089088
The eight parts of a tooth
- Enamel
- The outer white surface — the hardest substance in the body. Once damaged by decay or trauma, enamel does not regenerate.
- Dentin
- The yellow layer beneath enamel. Slightly softer, with microscopic tubules that connect to the pulp. Sensitivity to cold or sweet usually starts here.
- Pulp
- The soft tissue at the center of the tooth — nerves, blood vessels, and connective tissue. When the pulp becomes infected or inflamed, root canal therapy is needed to save the tooth.
- Cementum
- A thin calcified layer covering the root surface. It anchors the periodontal ligament fibers that hold the tooth in the bone.
- Root
- The portion of the tooth below the gumline. Front teeth typically have one root; molars have two or three roots, each with one or more canals.
- Canals
- The narrow channels inside each root that hold the pulp tissue. The number, shape, and curvature of canals vary widely from tooth to tooth — and sometimes from person to person on the same tooth. CBCT 3D imaging helps map them all.
- Apex
- The very tip of each root, where the canals open into the surrounding bone. Most root-tip infections show up here on imaging.
- Periodontal ligament
- A thin band of fibers attaching the tooth root to the surrounding bone. It absorbs chewing forces and is one reason a natural tooth performs better than an implant.
Frequently Asked Questions
- How long are tooth roots?
- Anterior teeth (front incisors and canines) have one root that is typically 12–17 mm long. Premolars are usually 13–16 mm. Molars have two or three roots, each generally 11–14 mm. The root is roughly 60% of the total tooth length, hidden in the bone.
- How many canals does a tooth have?
- It varies. Front teeth (incisors, canines) usually have one canal. Premolars have one or two. Lower molars typically have three; upper molars have three or four. Some teeth have unusual extra canals — missing one of these is a common cause of root canal failure, which is why endodontists use a microscope on every case.
- Do front teeth have roots?
- Yes — every tooth has at least one root. Front teeth (incisors and canines) have a single root, typically 12–17 mm long, hidden below the gumline.
- What does the root of a tooth look like?
- A tooth root is roughly cone-shaped, longer than the visible crown of the tooth, and tapers to a point (the apex) where the canals open into surrounding bone. Inside the root is a hollow canal containing pulp tissue. CBCT 3D imaging is the best way to see the full shape of any individual root.
- Why does the structure of a tooth matter for treatment?
- Endodontic outcomes depend almost entirely on canal anatomy: how many canals there are, how curved they are, whether any branch off, and whether they extend all the way to the apex. Missing one canal is the single most common reason root canals fail. Modern endodontic treatment uses a surgical microscope and CBCT 3D imaging precisely to see and treat the full anatomy.
Related: Root canal therapy · CBCT 3D imaging · Signs you need a root canal