title: Ultrastructural organization of dentin in mice lacking dentin sialo-phosphoprotein.
abstract: Dentin Sialophosphoprotein (DSPP) is the major non-collagenous protein of dentin and plays a significant role in dentin mineralization. Recently, animal models lacking DSPP have been developed and the DSPP KO phenotype has been characterized at the histological level. Little is known, however, about the DSPP KO dentin at nano- and meso-scale. Dentin is a hierarchical material spanning from nano- to macroscale, hence information on the effects of DSPP deficiency at the submicron scale is essential for understanding of its role in dentin biomineralization. To bridge this gap, we have conducted ultrastructural studies of dentin from DSPP KO animals. Transmission electron microscopy (TEM) studies of DSPP KO dentin revealed that although the overall ultrastructural organization was similar to the WT, the mineral particles were less organized. Scanning electron microscopy in the back-scattered mode (BS-SEM) of the DSPP KO dentin revealed that circumpulpal dentin comprises large areas of non-mineralized matrix, with numerous spherulitic mineralized inclusions, while the mantle dentin appeared largely unaffected. Analysis of the mineral distribution in the circumpulpal dentin of the DSPP KO mice suggests a reduction in the number of mineral nucleation sites and an increase in the nucleation barrier in DSPP KO dentin. These preliminary results indicate that in addition to the reduction of mineralized and total dentin volume in DSPP KO animals significant changes in the ultrastructural organization exist. These changes are likely related to the role of DSPP in the regulation of mineral formation and organization in dentin.
authors.affiliation: Department of Oral Biology, Center for Craniofacial Regeneration, McGowan Institute for Regenerative Medicine, University of Pittsburgh School of Dental Medicine , Pittsburgh, PA , USA and.
authors.forename: Ping-An
authors.initials: PA
authors.lastname: Fang
authors.forename: Kostas
authors.initials: K
authors.lastname: Verdelis
authors.forename: Xu
authors.initials: X
authors.lastname: Yang
authors.forename: Lyudmila
authors.initials: L
authors.lastname: Lukashova
authors.forename: Adele L
authors.initials: AL
authors.lastname: Boskey
authors.forename: Elia
authors.initials: E
authors.lastname: Beniash
mesh_terms: D000818:Animals; D003804:Dentin / Q000648:ultrastructure*; D003810:Dentinogenesis / Q000502:physiology*; D016326:Extracellular Matrix Proteins / Q000172:deficiency* / Q000648:ultrastructure*; D051379:Mice; D018345:Mice, Knockout; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D010641:Phenotype; D010750:Phosphoproteins / Q000172:deficiency* / Q000648:ultrastructure*; D012795:Sialoglycoproteins / Q000172:deficiency* / Q000648:ultrastructure*; D014074:Tooth Calcification / Q000502:physiology*; D000099311:Dentin Sialophosphoprotein
chemical_list: D016326:Extracellular Matrix Proteins; D010750:Phosphoproteins; D012795:Sialoglycoproteins; D000099311:Dentin Sialophosphoprotein
keywords: Biomineralization; calcium phosphate; dentinogenesis imperfecta; microCT; scanning electron microscopy; transmission electron microscopy