Tooth Enamel and Its Dynamic Protein Matrix

Abstract

Tooth enamel is the outer covering of tooth crowns, the hardest material in the mammalian body, yet fracture resistant. The extremely high content of 95 wt% calcium phosphate in healthy adult teeth is achieved through mineralization of a proteinaceous matrix that changes in abundance and composition. Enamel-specific proteins and proteases are known to be critical for proper enamel formation. Recent proteomics analyses revealed many other proteins with their roles in enamel formation yet to be unraveled. Although the exact protein composition of healthy tooth enamel is still unknown, it is apparent that compromised enamel deviates in amount and composition of its organic material. Why these differences affect both the mineralization process before tooth eruption and the properties of erupted teeth will become apparent as proteomics protocols are adjusted to the variability between species, tooth size, sample size and ephemeral organic content of forming teeth. This review summarizes the current knowledge and published proteomics data of healthy and diseased tooth enamel, including advancements in forensic applications and disease models in animals. A summary and discussion of the status quo highlights how recent proteomics findings advance our understating of the complexity and temporal changes of extracellular matrix composition during tooth enamel formation.

Novel Approach to Tooth Chemistry. Quantification of the Dental-Enamel Junction

“…Intermolecular interactions at the nanometer level and interactions of nano-and microcrystalline structures strongly determine the properties of each material, also biological ones. The bone and the dental structures are special examples of nano-and micro-composite materials, of which the constituent particles and macromolecular structures are both of organic and inorganic nature [1,2].…”

Organic Matrix of Enamel and Dentin and Developmental Defects

“…Enamel has 3 essential enamel proteins to build healthy well mineralized enamel which is secreted from ameloblasts "amelogenin, ameloblastin and enamelin" with the help of two enzymes, MMP20 and kallikrein-4 (Klk4) to form the enamel properly and sequent proteolysis of enamel protein [56]. In the event of alteration in the process of protein removal, enamel and dental defects will emerge like for example, amelogenesis imperfecta (AI), Chalky/Molar Hypomolarization (MH), Dentinogenesis Imperfecta (DI) or fluorosis [57]. Figure 3 depicts the protein content in healthy and diseased tooth.…”

Advances in biomineralization-inspired materials for hard tissue repair

“…Biomineralization of tooth enamel or amelogenesis is a biologically programmed sequence of several consecutive stages, including two major functional stages: secretory and maturation. 202 – 204 During the secretory stage, ameloblasts are mainly responsible for producing enamel matrix proteins and proteinases, which control the shape and arrangement of initially formed enamel crystals. 19 At the maturation stage, the thickness and width of enamel crystals greatly expand, accompanied by a decrease in protein abundance, and eventually form a highly mineralized tissue consisting of ~96 wt.% of mineral and a small amount of residual biomacromolecules and water.…”

“…At the maturation stage of enamel, the cleavage and degradation of the proteinaceous matrix via proteolytic processes are crucial for the formation of enamel with a high degree of mineralization. 202 A study by Moradian-Oldak et al 216 demonstrated that the occlusion of undegraded amelogenin inside enamel crystals of mice occurred due to the lack of matrix metalloprotease-20 (MMP-20) during amelogenesis. Due to amelogenin occlusion, the enamel crystals in MMP-20 null mice had uncommon sizes, morphologies, and crystallinities.…”