Cementum
Cementum
Cementum is a thin, bone-like calcified layer covering the root dentin. Periodontal ligament fibres are embedded in it, anchoring the tooth.
Overview
Cementum is about 45–50% mineral and resembles bone, but it has no blood vessels and does not normally remodel. Cementoblasts from the dental follicle make it. Acellular cementum covers the cervical part of the root. Cellular cementum, in which cementocytes sit in lacunae, covers the apical part and the area between roots. Cementum is laid down throughout life, especially near the apex, which compensates for wear of the biting surface. The collagen bundles of the periodontal ligament insert into it as Sharpey fibres.
- Location
Outer surface of the root, from the cemento-enamel junction to the apex.
Anatomy
- Histology
Lamellated mineralised matrix. It is acellular cervically and cellular apically (cementocytes in lacunae with canaliculi facing the periodontal ligament).
Function
- Attaches the periodontal ligament fibres to the tooth.
- Seals the root dentin.
- Continuous deposition maintains the tooth's position as it wears.
Clinical significance
Root exposure and hypercementosis
Gingival recession exposes thin cervical cementum, which wears easily and uncovers sensitive dentin. Hypercementosis (excess cementum) is seen in Paget disease of bone and can make extraction difficult.
Compiled from standard anatomy and physiology references — see the Digestive System sources. For education only; not medical advice.