[Frontiers in Bioscience 17, 1996-2023, June 1, 2012]

Protein - mediated enamel mineralization

Janet Moradian-Oldak1

1Center for Craniofacial Molecular Biology, University of Southern California, Ostrow School of Dentistry, 2250 Alcazar St. Los Angeles, CA, 90033 USA


1. Abstract
2. Introduction
3. Enamel bioceramic and its hierarchical structure
4. Initiation and stages of amelogenesis
5. The extracellular protein matrix
5.1. Amelogenin
5.1.1. The "unstructured" nature of amelogenin
5.1.2. In vitro amelogenin self-assembly into oligomers, nanospheres, and nanochains
5.1.3. Amelogenin self-assembly in vivo
5.1.4. Amelogenin function in controlling mineralization
5.2. Ameloblastin
5.2.1. Ameloblastin sequence and processing
5. 2.2. Ameloblastin putative function
5.3. Enamelin
5.3.1. Enamelin sequence and processing
5.3.2. There is no enamel without enamelin
5.3.3. The 32-kDa enamelin conformation and its interaction with mineral; In vitro models
5.3.4. Cooperation of amelogenin and enamelin in controlling crystal morphology
5.4. Amelotin
5.5. Enamel proteinases
5.5.1. Matrix metalloproteinase 20 (MMP-20)
5.5.2. Kallikrein-4 (KLK-4)
5.5.3. Caldecrin (Crtc)
6. Extracellar matrix pH changes and regulation
6.1. pH changes
6.2. pH regulation
6.3. Ion transport
7. Defective enamel
7.1. Amelogenesis imperfecta
8. Rebuilding enamel
8.1. Enamel-like material synthesis
8.2. Biomimetic enamel synthesis and remineralization
9. Summary and perspective
10 Acknowledgements
11. References


Enamel is a hard nanocomposite bioceramic with significant resilience that protects the mammalian tooth from external physical and chemical damages. The remarkable mechanical properties of enamel are associated with its hierarchical structural organization and its thorough connection with underlying dentin. This dynamic mineralizing system offers scientists a wealth of information that allows the study of basic principals of organic matrix-mediated biomineralization and can potentially be utilized in the fields of material science and engineering for development and design of biomimetic materials. This chapter will provide a brief overview of enamel hierarchical structure and properties as well as the process and stages of amelogenesis. Particular emphasis is given to current knowledge of extracellular matrix protein and proteinases, and the structural chemistry of the matrix components and their putative functions. The chapter will conclude by discussing the potential of enamel for regrowth.