Cementum is mineralized connective tissue produced by cementoblasts of the tooth. It covers the tooth roots, anchoring the tooth to the alveolar bone via the periodontal ligament. In addition, it serves as a protective layer over the dentin. Cementum consists of 45-50% inorganic material and has the highest fluoride content of all mineralized tissues. Cementoblasts are responsible for cementum deposition throughout life, and eventually become entrapped in their own cementum. When entrapped, they are known as cementocytes, and function to nourish the avascular cementum via the surrounding vascular periodontal ligament.