Regulated gene expression dictates enamel structure and tooth function

Altering Biomineralization by Protein Design

“…Of further interests is the biological control over mineral deposition in a process occurring at physiologic pH and temperature. Amelogenin is the most abundant protein of forming enamel, although other enamel proteins are known (4,44) and others have only been recently identified (45). Of the known enamel proteins, amelogenin is the only one known to self-assemble into nanospheres that appear to encase the long axis of the hydroxyapatite crystallites based on either transmission electron microscopy or by atomic force microscopy (22,46).…”

“…Amelogenin nanospheres appear to control the habit of hydroxyapatite crystallites by directing mineral growth to the ends (cЈ axis) of the crystallites by providing the space for crystallites to grow within and by buffering the local environment against protons liberated during mineral deposition (5, 7, 18 -20). The amino acid sequence of amelogenin is highly conserved among diverse vertebrate species, suggesting that conserved modular domains impart specific functions during biomineralization (4,16,21,22). To clarify the role that two of the conserved amelogenin domains contribute to the matrix that guides enamel biomineralization, we created knock-in mice by inserting an engineered amelogenin cDNA that lacked one of the two highly conserved domains.…”

“…A notable exception to such a biomineralization theme is found in enamel, the vertebrate covering of teeth. In teeth, ectoderm-derived ameloblasts synthesize a short-lived, diverse repertoire of proteins that self-assemble to produce a matrix that directs its own replacement by the mineral phase (4,5). Mature enamel is a bioceramic composed of less than 0.5% protein that is dispersed among the longest hydroxyapatite crystals in the vertebrate body (6 -8).…”

Calcium orthophosphates (CaPO 4 ): Occurrence and properties

“…Much is still unknown about the interactions among proteins present in enamel matrix and the final crystalline phase of biological apatite (Palmer et al 2008;Paine et al 2001). At some point before a tooth erupts into the mouth, the ameloblasts are broken down.…”

Mimicking the Self-Organized Microstructure of Tooth Enamel

“…The technical difficulties involved in directly evaluating the crystal nucleation rate have led to other approaches to initial crystallization events, and one of the most common ways to characterize the kinetics of nucleation is to measure the induction period (t s ) prior to nucleation at different supersaturations. The induction period can be expressed as eq 9: 19,52 (9) where κ [= 16πγ 3 Ω 2 /3(kT) 3 ] remains constant under a given set of conditions. V is the volume of the system, R s and N 0 are the radius of curvature and the density of the additives/substrates, respectively, and B is a kinetic constant.…”