Question

Describe the appearance of healed root surfaces.

Answer 1

Ans) Cementum covers the root surface and is an important tissue to maintain dental and periodontal attachment.

- 2–4 Light yellow in appearance, cementum is thinner near the tooth neck, about 20 to 50 microns thick, and about 150 to 200 microns thick at the root apex.

- Cementum is excreted by cells called cementoblasts, which develop from undifferentiated mesenchymal cells in the connective tissue of the dental sac.

- Cementum is slightly softer than dentin and consists of about 45–50% inorganic mineral (mainly the apatite crystals) by weight and 50–55% organic matter (mainly collagen and glycoproteins) and water by weight. Sharpey’s fibers (perforating fibers) are portions of the principal collagenous fibers of the periodontal ligament embedded in the cementum and alveolar bone that attach the tooth to the alveolus.

- Cementum is formed continuously throughout life because a new layer of cementum is deposited to keep the attachment intact as the superficial layer of cementum ages, but unlike bone tissue that can be constantly rebuilt and remodeled, cementum has a stronger anti-absorption capacity compared to the alveolar bone and is only capable of repairing itself to a limited degree.

- The structure of cementum is similar to the compact bone. Both are composed of cells and mineralized extracellular matrix. But unlike bone, there are no Haversian canals, blood vessels, and nerves in the cementum. Two kinds of cementum are formed, acellular and cellular, and fibers can be intrinsic or extrinsic, which results in four possible permutations.