Here are the tissues that make up the supporting structure of a tooth:
The gum (gingiva) is the pink-coloured soft tissue that covers the jaw bones and is visible in the mouth. It is firm and resilient with a textured surface. It forms a protective covering for the bone and the cementum (outer layer of roots) of the teeth.
The alveolar process is that part of the jaw bone which forms and supports the tooth sockets. It is formed during tooth eruption and gradually disappears after the tooth is lost. It undergoes remodelling throughout life by means of resorption and formation.
Periodontal ligament attaches the root of a tooth to the alveolar bone. Periodontal ligament has many functions. It supplies nutrients to the cementum, bone and gingiva through the blood vessels and protects the vessels and nerves of the tooth. It transmits chewing forces to the bone and acts as a shock absorber. It plays a part in tooth eruption and helps in formation and resorption of bone and cementum. It is also responsible for the sensations felt by the tooth.
Cementum covers the root of a tooth. It is hard as bone but is softer than enamel and dentin. It is the only supporting structure that is a part of a tooth. It helps the periodontal ligament to attach to the tooth. Cementum is of two types – acellular (primary) and cellular (secondary). Acellular cementum is formed before the tooth erupts completely. It does not contain cells. Cellular cementum is formed after the tooth erupts completely. It contains cells and is less calcified than the acellular type.