title: Human enamel phenotype associated with amelogenesis imperfecta and a kallikrein-4 (g.2142G>A) proteinase mutation.
abstract: Kallikrein-4 is known to be highly expressed during the maturation stage of enamel formation and is thought to be critical for the final phase of crystallite growth. The purpose of this study was to evaluate the enamel phenotype in humans with a known KLK-4 mutation (g.2142G>A). Primary teeth from two individuals with a known KLK-4 mutation were evaluated using amino acid analysis and light and electron microscopy. Light microscopy showed the enamel was of normal thickness but opaque throughout its width compared with normal enamel. Electron microscopy showed enamel affected by the KLK-4 mutation had a normal prismatic structure and generally had a well-organized and discernable crystallite composition. In some areas, globular structures were present where crystallites were not discernable or appeared to have an altered morphology. The KLK-4 mutant enamel had an increased protein content compared with normal enamel. Human enamel formed with a lack of functioning KLK-4 proteinase is altered primarily in the completeness of crystallite growth, while enamel thickness and prism structure remains essentially normal. Collectively, these studies suggest that the KLK-4 proteinase is essential for the final crystallite growth of enamel but is not critical for crystallite orientation, prism formation or enamel thickness.
authors: Department of Pediatric Dentistry, UNC Chapel Hill, NC 27599, USA. tim_wright@dentistry.unc.edu
authors: J Tim
authors: JT
authors: Wright
authors: Bill
authors: B
authors: Daly
authors: Darrin
authors: D
authors: Simmons
authors: Sung
authors: S
authors: Hong
authors: Suzanne P
authors: SP
authors: Hart
authors: Tom C
authors: TC
authors: Hart
authors: Phimon
authors: P
authors: Atsawasuwan
authors: Mitsuo
authors: M
authors: Yamauchi