H C Margolis

University of Pittsburgh, Pittsburgh, PA, United States

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Publications (65)180.23 Total impact

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    ABSTRACT: Amelogenin, the major extracellular enamel matrix protein, plays a critical role in regulating the growth and organization of enamel. Assembly and mineralization of full-length native (P173) and recombinant (rP172) porcine amelogenins were studied by cryogenic Transmission Electron Microscopy (cryoTEM). The cryoTEM revealed that both native and recombinant porcine amelogenins undergo step-wise self-assembly. Although the overall structural organization of P173 and rP172 oligomers was similar and resembled oligomers of murine recombinant amelogenin rM179, there were subtle differences suggesting that a single phosphorylated serine present in P173 might affect amelogenin self-assembly. Our mineralization studies demonstrated that both P173 and rP172 oligomers stabilize initial mineral clusters. Importantly, however, rP172 regulated the organization of initial mineral clusters into linear chains and guided the formation of parallel arrays of elongated mineral particles, which are the hallmark of enamel structural organization. These results are similar to those obtained previously using full-length recombinant murine amelogenin (Fang et al., 2011a). In contrast to that seen with rP172, phosphorylated P173 strongly inhibits mineralization for extended periods of time. We propose that these differences might be due to the differences in the structural organization and charge distribution between P173 and rP172. Overall our studies indicate that self-assembly of amelogenin and the mechanisms of its control over mineralization might be universal across different mammalian species. Our data also provide new insight into the effect of phosphorylation on amelogenin self-assembly and its regulation of mineralization.
    Journal of Structural Biology 05/2013; · 3.36 Impact Factor
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    ABSTRACT: Lhx6 is a LIM-homeobox transcription factor expressed during embryogenesis, however the molecular mechanisms regulating Lhx6 transcriptional activities are unknown. Lhx6 and the Pitx2 homeodomain transcription factor have overlapping expression patterns during tooth and craniofacial development and in this report we demonstrate new transcriptional mechanisms for these factors. Pitx2 and Lhx6 are co-expressed in the oral and dental epithelium and epithelial cell lines. Lhx6 expression is increased in Pitx2c transgenic mice and decreased in Pitx2 null mice. PITX2 activates endogenous Lhx6 expression and the Lhx6 promoter while Lhx6 represses its promoter activity. Chromatin immunoprecipiation experiments reveal endogenous Pitx2 binding to the Lhx6 promoter. Lhx6 directly interacts with PITX2 to inhibit PITX2 transcriptional activities and activation of multiple promoters. Bimolecular fluorescence complementation assays reveal an Lhx6-Pitx2 nuclear interaction in living cells. Lhx6 has a dominant repressive effect on the PITX2 synergistic activation with Lef-1 and β-catenin co-factors. Thus, Lhx6 acts as a transcriptional repressor and represses the expression of several genes involved in odontogenesis. We have identified specific defects in incisor, molar, mandible, bone and root development and late stage enamel formation in Lhx6 null mice. Amelogenin and ameloblastin expression is reduced and/or delayed in the Lhx6 null mice potentially resulting from defects in dentin deposition and ameloblast differentiation. Our results demonstrate that Lhx6 regulates cell proliferation in the cervical loop and promotes cell differentiation in the anterior region of the incisor. We demonstrate new molecular mechanisms for Lhx6 and an interaction with PITX2 for normal craniofacial and tooth development.
    Journal of Biological Chemistry 12/2012; · 4.65 Impact Factor
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    E Beniash, J P Simmer, H C Margolis
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    ABSTRACT: Amelogenin, the major protein of forming dental enamel, plays a crucial role in the biomineralization of this tissue. Amelogenin is soluble at low pH and self-assembles to form higher order structures at physiological pH. To understand the mechanisms of its assembly and interactions with calcium phosphate mineral, we conducted FTIR spectroscopy (FTIRS) studies of pH-triggered assembly of recombinant porcine amelogenin rP172 and its interactions with mature hydroxyapatite and apatitic mineral formed in situ. Analysis of our data indicated that rP172 at pH 3.0 exists in an unfolded disordered state, while increases in pH led to structural ordering, manifested by increases in intra- and intermolecular β-sheet structures and a decrease in random coil and β-turns. Amelogenin assembled at pH 7.2 was also found to contain large portions of extended intramolecular β-sheet and PPII. These FTIRS findings are consistent with those previously obtained with other techniques, thus verifying the validity of our experimental approach. Interestingly, interactions with mineral led to a reduction in protein structural organization. The findings obtained show that amelogenin has intrinsic structural flexibility to accommodate interactions with both forming and mature calcium phosphate mineral phases, providing new insights into the potential importance of amelogenin-mineral interactions in enamel biomineralization.
    Journal of dental research 08/2012; 91(10):967-72. · 3.46 Impact Factor
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    ABSTRACT: Background: Growth factors such as platelet derived growth factor (PDGF) have significantly enhanced periodontal therapy outcomes but with a high degree of variability, mostly due to lack of their continual supply for a required period of time. One method to overcome this barrier is gene therapy and the aim of this in vitro study is to evaluate PDGF-B gene delivery in fibroblasts using nano-sized calcium phosphate particles (NCaPP) as vectors. Methods: NCaPP incorporating green fluorescent protein, GFP (NCaPP-GFP) and PDGF-B (NCaPP-PDGF-B) plasmids were synthesized using an established precipitation system and characterized using transmission electron microscopy and 1.2% agarose gel electrophoresis. Biocompatibility and transfection of the nanoplexes in fibroblasts were evaluated using cytotoxicity assay and florescence microscopy, respectively. Polymerase chain reaction (PCR) and enzyme linked Immunosorbent assay (ELISA) were performed to evaluate PDGF-B transfection after different time points of treatments and the functionality of PDGF-B transfection was evaluated using the cell proliferation assay. Results: Synthesized NCaPP nanoplexes incorporating the genes of GFP and PDGF-B were spherical in shape and measured about 30 to 50 nm in diameter. Gel electrophoresis confirmed DNA incorporation and stability within the nanoplexes and MTS assay demonstrated their biocompatibility in fibroblasts. In vitro transfection studies revealed a higher and longer lasting transfection after NCaPP-PDGF-B treatment, which lasted up to 96 hours. Significantly enhanced fibroblast proliferation observed in NCaPP-PDGF-B treated cells confirmed the functionality of these nanoplexes. Conclusion: NCaPP demonstrated higher levels of biocompatibility and efficiently transfected PDGF plasmids into fibroblasts under described in vitro conditions.
    Journal of Periodontology 03/2012; · 2.40 Impact Factor
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    ABSTRACT: Amelogenin undergoes self-assembly and plays an essential role in guiding enamel mineral formation. The leucine-rich amelogenin peptide (LRAP) is an alternative splice product of the amelogenin gene and is composed of the N terminus (containing the only phosphate group) and the C terminus of full-length amelogenin. This study was conducted to investigate further the role of phosphorylation in LRAP self-assembly in the presence and absence of calcium using small angle X-ray scattering (SAXS). Consistent with our previous dynamic light-scattering findings for phosphorylated (+P) and non-phosphorylated (-P) LRAP, SAXS analyses revealed radii of gyration (R(g)) for LRAP(-P) (46.3-48.0 Å) that were larger than those for LRAP(+P) (25.0-27.4 Å) at pH 7.4. However, added calcium (up to 2.5 mM) induced significant increases in the R(g) of LRAP(+P) (up to 46.4 Å), while it had relatively little effect on LRAP(-P) particle size. Furthermore, SAXS analyses suggested compact folded structures for LRAP(-P) in the presence and absence of calcium, whereas the conformation of LRAP(+P) changed from an unfolded structure to a more compact structure upon the addition of calcium. We conclude that the single phosphate group in LRAP(+P) induces functionally important conformational changes, suggesting that phosphorylation may also influence amelogenin conformation and protein-mineral interactions during the early stages of amelogenesis.
    European Journal Of Oral Sciences 12/2011; 119 Suppl 1:97-102. · 1.42 Impact Factor
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    ABSTRACT: Amelogenin is essential for proper enamel formation. The present in vitro study extends our previous work at low (10 mM) ionic strength (IS) by examining the effect of amelogenin on mineralization under higher (162 mM) IS conditions found in developing enamel. Full-length phosphorylated (P173) and non-phosphorylated (rP172) amelogenins were examined, along with P148 and rP147 that lack the hydrophilic C-terminus. Calcium phosphate formation was assessed by pH change, while the minerals formed were characterized using transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy. Amelogenin self-assembly was also studied using dynamic light scattering and TEM. The results indicate that IS does not influence the effects of rP147, rP172, and P173 on mineralization. However, in contrast to the findings for low IS, where both P173 and P148 stabilize initially formed amorphous calcium phosphate (ACP) nanoparticles for >1 d, elongated hydroxyapatite crystals were observed after 24 h using P148 at high IS, unlike that seen with P173. Differences in self-assembly help explain these findings, which suggest that P173 and P148 may play different roles in regulating enamel mineral formation. The present data support the notion that proteolytic processing of P173 is required in vivo to induce the transformation of initial ACP phases to apatitic enamel crystals.
    European Journal Of Oral Sciences 12/2011; 119 Suppl 1:103-11. · 1.42 Impact Factor
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    ABSTRACT: Enamel is a highly organized hierarchical nanocomposite, which consists of parallel arrays of elongated apatitic crystallites forming an intricate three-dimensional microstructure. Amelogenin, the major extracellular matrix protein of dental enamel, regulates the formation of these crystalline arrays via cooperative interactions with forming mineral phase. Using cryoelectron microscopy, we demonstrate that amelogenin undergoes stepwise hierarchical self-assembly. Furthermore, our results indicate that interactions between amelogenin hydrophilic C-terminal telopeptides are essential for oligomer formation and for subsequent steps of hierarchical self-assembly. We further show that amelogenin assemblies stabilize mineral prenucleation clusters and guide their arrangement into linear chains that organize as parallel arrays. The prenucleation clusters subsequently fuse together to form needle-shaped mineral particles, leading to the formation of bundles of crystallites, the hallmark structural organization of the forming enamel at the nanoscale. These findings provide unique insight into the regulation of biological mineralization by specialized macromolecules and an inspiration for bottom-up strategies for the materials design.
    Proceedings of the National Academy of Sciences 08/2011; 108(34):14097-102. · 9.74 Impact Factor
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    ABSTRACT: Amelogenin's capacity to regulate enamel formation is related to its conserved N- and C-terminal domains, its ability to self-assemble, and its ability to stabilize amorphous calcium phosphate (ACP) - a capacity enhanced by amelogenin phosphorylation. This in vitro study provides further insight into amelogenin function, using variations of the Leucine-Rich Amelogenin Peptide (LRAP), an alternative splice product comprised solely of amelogenin's N- and C-terminal domains. Peptide self-assembly was studied by dynamic light-scattering and transmission electron microscopy (TEM). TEM, selected area electron diffraction, and Fourier transform-infrared spectroscopy were also used to determine the effect of phosphorylated and non-phosphorylated LRAP on calcium phosphate formation. Results show that phosphorylated and non-phosphorylated LRAP can self-assemble into chain-like structures in a fashion dependent on the C-terminal domain. Notably, this capacity was enhanced by added calcium and to a much greater degree for phosphorylated LRAP. Furthermore, phosphorylated LRAP was found to stabilize ACP and prevent its transformation to hydroxyapatite (HA), while aligned HA crystals formed in the presence of non-phosphorylated LRAP. The N- and C-terminal amelogenin domains in non-phosphorylated LRAP are, therefore, sufficient to guide ACP transformation into ordered bundles of apatite crystals, making LRAP an excellent candidate for biomimetic approaches for enamel regeneration.
    Journal of dental research 06/2011; 90(9):1091-7. · 3.46 Impact Factor
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    ABSTRACT: Cryogenic transmission electron microscopy (cryo-EM) was used to explore the self-assembly of recombinant murine amelogenin (rM179) in vitro. Our cryo-EM data showed that amelogenin self-assembly is a strongly pH-dependent process. At pH 4.4 the main fraction of the protein exists in a monomeric form, although some peculiar structures consisting of chains of monomers were also observed. At pH 5.8 large nanospheres comprising ring-like structures ~50 nm in diameter were the most abundant particle class. Similarly, at pH 8.0 amelogenins self-assembled into ring-like oligomers of different sizes, which subsequently assembled into nanospheres 15-20 nm in diameter. Furthermore, at pH 7.2, which is close to a physiological pH, branched chains of nanospheres were observed. Our results show that amelogenin assembly is a multistep hierarchical process and provides new insight into the control of enamel mineralization.
    Cells Tissues Organs 05/2011; 194(2-4):166-70. · 1.96 Impact Factor
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    ABSTRACT: N-terminal and C-terminal (CT) domains of amelogenin have been shown to be essential for proper enamel formation. Recent studies have also suggested that although the C-terminus plays an apparent role in protein-mineral interactions, other amelogenin structural domains are involved. The objective was to explore the role of the amelogenin N-terminus in the regulation of calcium phosphate formation in vitro. Spontaneous mineralization studies were carried out using the phosphorylated (+P) and nonphosphorylated (-P) N-terminus of the leucine-rich amelogenin peptide (LRAP) that lacks the hydrophilic CT domain. Mineralization progress was monitored via changes in solution pH. Mineral phases formed were characterized using TEM, selected area electron diffraction, and FT-IR. In controls, amorphous calcium phosphate was initially formed and subsequently transformed to randomly oriented hydroxyapatite (HA) plate-like crystals. In contrast to the control, LRAP(+P)-CT stabilized ACP formation for >1 day, while LRAP(-P)-CT accelerated the transformation of ACP to HA but had little effect on crystal shape or orientation. In conclusion, the N-terminal domain found in LRAP, as in amelogenins, appears to have the capacity to interact with forming calcium phosphate mineral phases. Results suggest that the N-terminal domain of amelogenin may play a direct role in early stages of enamel formation.
    Cells Tissues Organs 05/2011; 194(2-4):188-93. · 1.96 Impact Factor
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    ABSTRACT: The self-assembly of the predominant extracellular enamel matrix protein amelogenin plays an essential role in regulating the growth and organization of enamel mineral during early stages of dental enamel formation. The present study describes the effect of the phosphorylation of a single site on the full-length native porcine amelogenin P173 on self-assembly and on the regulation of spontaneous calcium phosphate formation in vitro. Studies were also conducted using recombinant non-phosphorylated (rP172) porcine amelogenin, along with the most abundant amelogenin cleavage product (P148) and its recombinant form (rP147). Amelogenin self-assembly was assessed using dynamic light scattering (DLS) and transmission electron microscopy (TEM). Using these approaches, we have shown that self-assembly of each amelogenin is very sensitive to pH and appears to be affected by both hydrophilic and hydrophobic interactions. Furthermore, our results suggest that the phosphorylation of the full-length porcine amelogenin P173 has a small but potentially important effect on its higher-order self-assembly into chain-like structures under physiological conditions of pH, temperature, and ionic strength. Although phosphorylation has a subtle effect on the higher-order assembly of full-length amelogenin, native phosphorylated P173 was found to stabilize amorphous calcium phosphate for extended periods of time, in sharp contrast to previous findings using non-phosphorylated rP172. The biological relevance of these findings is discussed.
    Journal of Structural Biology 11/2010; 173(2):250-60. · 3.36 Impact Factor
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    ABSTRACT: MicroRNAs are known to regulate gene function in many tissues and organs, but their expression and function, if any, in tooth development are elusive. We sought to identify them by microRNA screening analyses and reveal their overall roles by inactivating Dicer1 in the dental epithelium and mesenchyme. Discrete sets of microRNAs are expressed in molars compared with incisors as well as epithelium compared with mesenchyme. Conditional knockout (cKO) of Dicer1 (mature microRNAs) in the dental epithelium of the Pitx2-Cre mouse results in multiple and branched enamel-free incisors and cuspless molars, and change in incisor patterning and in incisor and molar size and shape. Analyses of differentiating dental epithelial markers reveal a defect in ameloblast differentiation. Conversely, the cervical loop (stem cell niche) is expanded in Dicer1 cKO. These results demonstrate that tooth development is tightly controlled by microRNAs and that specific microRNAs regulate tooth epithelial stem cell differentiation.
    Journal of dental research 08/2010; 89(8):779-84. · 3.46 Impact Factor
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    ABSTRACT: Collagen and amelogenin are two major extracellular organic matrix proteins of dentin and enamel, the mineralized tissues comprising a tooth crown. They both are present at the dentin-enamel boundary (DEB), a remarkably robust interface holding dentin and enamel together. It is believed that interactions of dentin and enamel protein assemblies regulate growth and structural organization of mineral crystals at the DEB, leading to a continuum at the molecular level between dentin and enamel organic and mineral phases. To gain insight into the mechanisms of the DEB formation and structural basis of its mechanical resiliency we have studied the interactions between collagen fibrils, amelogenin assemblies, and forming mineral in vitro, using electron microscopy. Our data indicate that collagen fibrils guide assembly of amelogenin into elongated chain or filament-like structures oriented along the long axes of the fibrils. We also show that the interactions between collagen fibrils and amelogenin-calcium phosphate mineral complexes lead to oriented deposition of elongated amorphous mineral particles along the fibril axes, triggering mineralization of the bulk of collagen fibril. The resulting structure was similar to the mineralized collagen fibrils found at the DEB, with arrays of smaller well organized crystals inside the collagen fibrils and bundles of larger crystals on the outside of the fibrils. These data suggest that interactions between collagen and amelogenin might play an important role in the formation of the DEB providing structural continuity between dentin and enamel.
    Journal of Biological Chemistry 06/2010; 285(25):19277-87. · 4.65 Impact Factor
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    ABSTRACT: Understanding the composition and function of the acquired enamel pellicle (AEP) has been a major goal in oral biology. The aim of this study was to test the hypothesis that intact histatins are part of the in vivo AEP and that histatins after adsorption to HA have effects on in vitro enamel demineralization. This is the first study demonstrating the presence of intact histatins in vivo in the AEP. The in vitro experiments show that all naturally occurring histatins in the AEP have the potential to provide some level of protection against acid injury.
    Journal of dental research 03/2010; 89(6):626-30. · 3.46 Impact Factor
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    ABSTRACT: It is well-known that amelogenin self-assembles to form nanoparticles, usually referred to as amelogenin nanospheres, despite the fact that not much is known about their actual shape in solution. In the current paper, we combine SAXS and DLS to study the three-dimensional shape of the recombinant amelogenins rP172 and rM179. Our results show for the first time that amelogenins build oblate nanoparticles in suspension using experimental approaches that do not require the proteins to be in contact with a support material surface. The SAXS studies give evidence for the existence of isolated amelogenin nano-oblates with aspect ratios in the range of 0.45-0.5 at pH values higher than pH 7.2 and show an aggregation of these nano-oblates at lower pH values. The role of the observed oblate shape in the formation of chain-like structures at physiological conditions is discussed as a key factor in the biomineralization of dental enamel.
    Biomacromolecules 02/2010; 11(2):369-76. · 5.37 Impact Factor
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    ABSTRACT: Extracellular matrix molecules play a critical role in regulating biological mineralization. This brief review describes recent advances made in our laboratory on elucidating the role of amelogenin, the predominant enamel matrix protein, in regulating the formation of the highly organized enamel tissue. Based on results obtained using dynamic light scattering, transmission electron microscopy, and small-angle X-ray scattering, we have found that the self-assembly of amelogenins is primarily regulated by pH and that the full-length amelogenin can form higher-order chain-like structures. These latter structures are comprised of uniformly sized aggregates of amelogenin called nanospheres. Based on in vitro mineralization studies, full-length amelogenin was also found to uniquely regulate the formation of parallel arrays of hydroxyapatite crystals. The unique ability of full-length amelogenin to form chain-like structures and induce organized mineral formation was dependent upon the presence of its hydrophilic C terminus. Key wordsamelogenesis-amelogenin-dental enamel-mineralization-calcium phosphates
    12/2009: pages 369-374;
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    ABSTRACT: The potential role of amelogenin phosphorylation in enamel formation has been elucidated through in vitro mineralization studies. Studies focused on the native 20-kDa porcine amelogenin proteolytic cleavage product P148 that is prominent in developing enamel. Under conditions of spontaneous calcium phosphate precipitation, in the presence of nonphosphorylated recombinant full-length porcine amelogenin, rP172, immediately formed nanoparticles of amorphous calcium phosphate (ACP) were found to transform into parallel arrays of needle-like apatitic crystals. In contrast to these findings, P148, with a single phosphate group on serine-16, was found to inhibit calcium phosphate precipitation and stabilize ACP formation for more than 1 day. The present study has provided evidence suggesting that the proteolytic cleavage product P148 may have an important functional role in regulating mineralization during enamel formation. Key wordsenamel-amelogenin-biomineralization-hydroxyapatite
    12/2009: pages 418-420;
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    ABSTRACT: The potential role of amelogenin phosphorylation in enamel formation is elucidated through in vitro mineralization studies. Studies focused on the native 20-kDa porcine amelogenin proteolytic cleavage product P148 that is prominent in developing enamel. Experimental conditions supported spontaneous calcium phosphate precipitation with the initial formation of amorphous calcium phosphate (ACP). In the absence of protein, ACP was found to undergo relatively rapid transformation to randomly oriented plate-like apatitic crystals. In the presence of non-phosphorylated recombinant full-length amelogenin, rP172, a longer induction period was observed during which relatively small ACP nanoparticles were transiently stabilized. In the presence of rP172, these nanoparticles were found to align to form linear needle-like particles that subsequently transformed and organized into parallel arrays of apatitic needle-like crystals. In sharp contrast to these findings, P148, with a single phosphate group on serine 16, was found to inhibit calcium phosphate precipitation and stabilize ACP formation for more than 1 day. Additional studies using non-phosphorylated recombinant (rP147) and partially dephosphorylated forms of P148 (dephoso-P148) showed that the single phosphate group in P148 was responsible for the profound effect on mineral formation in vitro. The present study has provided, for the first time, evidence suggesting that the native proteolytic cleavage product P148 may have an important functional role in regulating mineralization during enamel formation by preventing unwanted mineral formation within the enamel matrix during the secretory stage of amelogenesis. Results obtained have also provided new insights into the functional role of the highly conserved hydrophilic C terminus found in full-length amelogenin.
    Journal of Biological Chemistry 06/2009; 284(28):18972-9. · 4.65 Impact Factor
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    M Baldassarri, H C Margolis, E Beniash
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    ABSTRACT: Dental enamel is comprised primarily of carbonated apatite, with less than 1% w/w organic matter and 4-5% w/w water. To determine the influence of each component on the microhardness and fracture toughness of rat incisor enamel, we mechanically tested specimens in which water and organic matrix were selectively removed. Tests were performed in mid-sagittal and transverse orientations to assess the effect of the structural organization on enamel micromechanical properties. While removal of organic matrix resulted in up to a 23% increase in microhardness, and as much as a 46% decrease in fracture toughness, water had a significantly lesser effect on these properties. Moreover, removal of organic matrix dramatically weakened the dentino-enamel junction (DEJ). Analysis of our data also showed that the structural organization of enamel affects its micromechanical properties. We anticipate that these findings will help guide the development of bio-inspired nanostructured materials for mineralized tissue repair and regeneration.
    Journal of Dental Research 08/2008; 87(7):645-9. · 3.83 Impact Factor
  • H Yamazaki, H C Margolis
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    ABSTRACT: We conducted this study to test the hypothesis that acidic solutions undersaturated with respect to enamel and supersaturated with respect to fluorapatite can enhance enamel remineralization by reducing preferential remineralization of the outer lesion and promoting mineral ion penetration. We used quantitative microradiography to assess mineral changes in artificial surface-softened and subsurface lesions in human enamel in vitro, induced by such an acidic solution and by a neutral remineralizing solution. For surface-softened lesions, the extent of remineralization was similar for both solutions, although preferential remineralization of the outer lesion was observed with the neutral solution. For subsurface lesions, preferential remineralization of the outer lesion was not observed with either solution. However, the extent of subsurface lesion remineralization by the acidic solution was significantly greater than that observed with the neutral solution. Results obtained are noted to reflect inherent differences in lesion type and the properties of the solutions studied.
    Journal of Dental Research 07/2008; 87(6):569-74. · 3.83 Impact Factor

Publication Stats

2k Citations
180.23 Total Impact Points

Institutions

  • 2010–2013
    • University of Pittsburgh
      • Oral Biology
      Pittsburgh, PA, United States
    • The University of Western Ontario
      • Schulich School of Medicine and Dentistry
      London, Ontario, Canada
  • 1997–2011
    • The Forsyth Institute
      • Department of Cytokine Biology
      Cambridge, Massachusetts, United States
    • Beijing Medical University
      • School of Stomatology
      Peping, Beijing, China
  • 2006
    • Boston University
      • Department of Periodontology and Oral Biology
      Boston, MA, United States
  • 2005
    • Université de Montréal
      • Department of Stomatology
      Montréal, Quebec, Canada
  • 1997–2000
    • Colgate-Palmolive
      New York City, New York, United States
  • 1996
    • McGill University
      • Department of Anatomy and Cell Biology
      Montréal, Quebec, Canada