Warning: Undefined variable $zfal in C:\Inetpub\vhosts\kidney.de\httpdocs\mlpefetch.php on line 525
Deprecated: str_replace(): Passing null to parameter #3 ($subject) of type array|string is deprecated in C:\Inetpub\vhosts\kidney.de\httpdocs\mlpefetch.php on line 525
Warning: Undefined variable $sterm in C:\Inetpub\vhosts\kidney.de\httpdocs\mlpefetch.php on line 530
Warning: Undefined variable $sterm in C:\Inetpub\vhosts\kidney.de\httpdocs\mlpefetch.php on line 531
 
English Wikipedia
Nephropedia Template TP (
Twit Text
DeepDyve
Pubget Overpricing |  
lüll
Cellular and chemical events during enamel maturation Smith CECrit Rev Oral Biol Med 1998[]; 9 (2): 128-61This review focuses on the process of enamel maturation, a series of events associated with slow, progressive growth in the width and thickness of apatitic crystals. This developmental step causes gradual physical hardening and transformation of soft, newly formed enamel into one of the most durable mineralized tissues produced biologically. Enamel is the secretory product of specialized epithelial cells, the ameloblasts, which make this covering on the crowns of teeth in two steps. First, they roughly "map out" the location and limits (overall thickness) of the entire extracellular layer as a protein-rich, acellular, and avascular matrix filled with thin, ribbon-like crystals of carbonated hydroxyapatite. These initial crystals are organized spatially into rod and interrod territories as they form, and rod crystals are lengthened by Tomes' processes in tandem with appositional movement of ameloblasts away from the dentin surface. Once the full thickness of enamel has been formed, ameloblasts initiate a series of repetitive morphological changes at the enamel surface in which tight junctions and deep membrane infoldings periodically appear (ruffle-ended), then disappear for short intervals (smooth-ended), from the apical ends of the cells. As this happens, the enamel covered by these cells changes rhythmically in net pH from mildly acidic (ruffle-ended) to near-physiologic (smooth-ended) as mineral crystals slowly expand into the "spaces" (volume) formerly occupied by matrix proteins and water. Matrix proteins are processed and degraded by proteinases throughout amelogenesis, but they undergo more rapid destruction once ameloblast modulation begins. Ruffle-ended ameloblasts appear to function primarily as a regulatory and transport epithelium for controlling the movement of calcium and other ions such as bicarbonate into enamel to maintain buffering capacity and driving forces optimized for surface crystal growth. The reason ruffle-ended ameloblasts become smooth-ended periodically is unknown, although this event seems to be crucial for sustaining long-term crystal growth.|Ameloblasts/*cytology/metabolism/physiology[MESH]|Amelogenesis/*physiology[MESH]|Apatites/metabolism[MESH]|Bicarbonates/metabolism[MESH]|Biological Transport[MESH]|Body Water/metabolism[MESH]|Buffers[MESH]|Calcium/metabolism[MESH]|Cell Membrane/metabolism/physiology/ultrastructure[MESH]|Cell Movement[MESH]|Crystallization[MESH]|Dental Enamel/cytology/growth & development/*metabolism[MESH]|Dentin/anatomy & histology[MESH]|Durapatite/metabolism[MESH]|Endopeptidases/metabolism[MESH]|Extracellular Matrix Proteins/metabolism[MESH]|Extracellular Matrix/metabolism/physiology/ultrastructure[MESH]|Humans[MESH]|Hydrogen-Ion Concentration[MESH]|Tooth Calcification/physiology[MESH]|Tooth Crown/cytology/growth & development/metabolism[MESH] |
