Chapter 2. Review of the literature
- Table of Contents
- 2.1. Tooth structure
- 2.2. Dentin-pulp complex
- 2.3. Dentin formation and mineralization
- 2.4. Organic matrix of dentin
- 2.5. Growth factors in dentin-pulp complex
- 2.6. Dentin demineralization and destruction
- 2.7. Metalloproteinase superfamily
- 2.8. Matrix metalloproteinases (MMPs)
- 2.9. Transcriptional regulation of MMPs
- 2.10. Activation of proMMPs
- 2.11. Inhibition of MMP activities
- 2.12. Suggested roles for MMPs and TIMPs in dentin-pulp complex
2.1. Tooth structure
Macroscopically, a tooth is divided into a crown and a root (Fig. 1). The mature human tooth proper consists of three hard tissues; the crown is covered by enamel, which is hard and completely acellular and the most mineralized tissue found in the body. It consists of 95% inorganic hydroxyapatite crystallites (Ca10(PO4)6(OH)2) (all percentages as chemically by weight), the rest of the matrix being water (4%) and proteins (1%). The root is covered by cementum, which is 50% mineralized with hydroxyapatite crystals and has a collagen organic matrix. Below the enamel and cementum is a third hard tissue, dentin, which forms the bulk of the tooth. It is 70% mineralized with hydroxyapatite crystals, and organic material of the dentin is mainly fibrous collagen and comprises 20% of the matrix, while the remaining 10% is water. Mineralized dentin together with the pulp tissue form the dentin-pulp complex, which is responsible for the formation and maintainence of the tooth mass. (Ten Cate 1994a, Torneck 1994.)
