1
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Ngu J, Bronckers ALJJ, Katsura K, Zhang Y, Den Besten PK. Na + and K + transport and maturation stage ameloblast modulation. Front Physiol 2023; 14:1124444. [PMID: 36814472 PMCID: PMC9939811 DOI: 10.3389/fphys.2023.1124444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 01/13/2023] [Indexed: 02/08/2023] Open
Abstract
Introduction: Enamel mineralization requires calcium transport into the extracellular matrix for the synthesis of hydroxyapatite (HA) crystals. Formation of HA releases protons into the matrix, which are then neutralized when ameloblasts modulate from cells with apical invaginations, the so-called ruffle-ended ameloblasts (RE), to smooth-ended ameloblasts (SE). Ameloblast modulation is associated with the translocation of the calcium exchanger Nckx4 to the apical border of RE, to remove Na+ from the enamel matrix in exchange for Ca2+ and K+. As enamel matures, Na+ and K+ in the matrix progressively decrease. However, the transporter to remove K+ from mineralizing enamel has not been identified. Methods: Expression of K+ exchangers and channels in secretory and maturation stage of enamel organs were compared following an RNA-seq analysis. Kcnj15, which encodes the Kir4.2 inwardly rectifying K+ channel, was found to be the most upregulated internalizing K+ transporter in maturation stage of enamel organs. Kir4.2 was immunolocalized in wt, Nckx4-/-, Wdr72-/-, and fluorosed ameloblasts. Regulation of Wdr72 expression by pH was characterized in vitro and in vivo. Results: Kir4.2 immunolocalized to the apical border of wild type (wt) mouse RE and cytosol of SE, a spatial distribution pattern shared by NCKX4. In Nckx4-/- ameloblasts, Kir4.2 also localized to the apical surface of RE and cytosol of SE. However, in fluorosed and Wdr72-/- ameloblasts, in which vesicle trafficking is disrupted, Kir4.2 remained in the cytosol. In vitro, Wdr72 was upregulated in LS8 cells cultured in medium with a pH 6.2, which is the pH of the enamel matrix underlying RE, as compared to pH 7.2 under SE. Conclusion: Taken together these results suggest that Kir4.2 participates in K+ uptake by maturation ameloblasts, and that K+ and Na+ uptake by Kir4.2 and Nckx4, respectively, may be regulated by pH through WDR72-mediated endocytosis and membrane trafficking.
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Affiliation(s)
- Jake Ngu
- Department of Orofacial Sciences, University of California, San Francisco, San Francisco, CA, United States
| | - Antonius L. J. J. Bronckers
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), MOVE Research Institute, University of Amsterdam and VU University, Amsterdam, Netherlands
| | - Kaitlin Katsura
- Department of Orofacial Sciences, University of California, San Francisco, San Francisco, CA, United States
| | - Yan Zhang
- Department of Orofacial Sciences, University of California, San Francisco, San Francisco, CA, United States
| | - Pamela K. Den Besten
- Department of Orofacial Sciences, University of California, San Francisco, San Francisco, CA, United States
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2
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Red Marine Algae Lithothamnion calcareum Supports Dental Enamel Mineralization. Mar Drugs 2023; 21:md21020109. [PMID: 36827150 PMCID: PMC9963885 DOI: 10.3390/md21020109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 01/25/2023] [Accepted: 01/27/2023] [Indexed: 02/05/2023] Open
Abstract
The current management of oral conditions such as dental caries and erosion mostly relies on fluoride-based formulations. Herein, we proposed the use of the remaining skeleton of Lithothamnion calcareum (LC) as an alternative to fluorides. LC is a red macroalgae of the Corallinales order, occurring in the northeast coast of Brazil, whose unique feature is the abundant presence of calcium carbonates in its cell walls. Two experimental approaches tested the general hypothesis that LC could mediate enamel de-remineralization dynamics as efficiently as fluorides. Firstly, the effect of LC on enamel de-mineralization was determined in vitro by microhardness and gravimetric measurements to test the hypothesis that LC could either prevent calcium/phosphate release from intact enamel or facilitate calcium/phosphate reprecipitation on an artificially demineralized enamel surface. Subsequently, an in situ/ex vivo co-twin control study measured the effect of LC on the remineralization of chemical-demineralized enamel using microhardness and quantitative light-induced fluorescence. With this second experiment, we wanted to test whether outcomes obtained in experiment 1 would be confirmed by an in situ/ex vivo co-twin control model. Both experiments showed that LC exhibited equivalent or superior ability to modulate enamel de-remineralization when compared to fluoride solution. LC should be explored as an alternative to manage oral conditions involving the enamel demineralization.
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3
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Obtel N, Le Cabec A, Nguyen TN, Giabicani E, Van Malderen SJM, Garrevoet J, Percot A, Paris C, Dean C, Hadj‐Rabia S, Houillier P, Breiderhoff T, Bardet C, Coradin T, Ramirez Rozzi F, Chaussain C. Impact of claudin-10 deficiency on amelogenesis: Lesson from a HELIX tooth. Ann N Y Acad Sci 2022; 1516:197-211. [PMID: 35902997 PMCID: PMC9796262 DOI: 10.1111/nyas.14865] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In epithelia, claudin proteins are important components of the tight junctions as they determine the permeability and specificity to ions of the paracellular pathway. Mutations in CLDN10 cause the rare autosomal recessive HELIX syndrome (Hypohidrosis, Electrolyte imbalance, Lacrimal gland dysfunction, Ichthyosis, and Xerostomia), in which patients display severe enamel wear. Here, we assess whether this enamel wear is caused by an innate fragility directly related to claudin-10 deficiency in addition to xerostomia. A third molar collected from a female HELIX patient was analyzed by a combination of microanatomical and physicochemical approaches (i.e., electron microscopy, elemental mapping, Raman microspectroscopy, and synchrotron-based X-ray fluorescence). The enamel morphology, formation time, organization, and microstructure appeared to be within the natural variability. However, we identified accentuated strontium variations within the HELIX enamel, with alternating enrichments and depletions following the direction of the periodical striae of Retzius. These markings were also present in dentin. These data suggest that the enamel wear associated with HELIX may not be related to a disruption of enamel microstructure but rather to xerostomia. However, the occurrence of events of strontium variations within dental tissues might indicate repeated episodes of worsening of the renal dysfunction that may require further investigations.
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Affiliation(s)
- Nicolas Obtel
- Université Paris Cité, URP2496 Pathologies, Imagerie et Biothérapies Orofaciales et Plateforme Imagerie du Vivant (PIV), FHU‐DDS‐net, IHMOA, Dental SchoolMontrougeFrance,AP‐HP Services de médecine bucco‐dentaire, Hôpitaux Universitaires Bretonneau (CRMR phosphore et calcium, filière OSCAR et ERN Bond) and Charles Foix, FHU DDS‐netIle de FranceFrance
| | - Adeline Le Cabec
- Univ. Bordeaux, CNRS, MCC, PACEA, UMR 5199PessacFrance,Department of Human EvolutionMax Planck Institute for Evolutionary AnthropologyLeipzigGermany
| | - Thè Nghia Nguyen
- Université Paris Cité, URP2496 Pathologies, Imagerie et Biothérapies Orofaciales et Plateforme Imagerie du Vivant (PIV), FHU‐DDS‐net, IHMOA, Dental SchoolMontrougeFrance
| | - Eloise Giabicani
- Université Paris Cité, URP2496 Pathologies, Imagerie et Biothérapies Orofaciales et Plateforme Imagerie du Vivant (PIV), FHU‐DDS‐net, IHMOA, Dental SchoolMontrougeFrance
| | | | | | - Aline Percot
- Sorbonne Université, CNRS, De la Molécule aux Nano‐Objets: Réactivité, Interactions et Spectroscopies (MONARIS)ParisFrance
| | - Céline Paris
- Sorbonne Université, CNRS, De la Molécule aux Nano‐Objets: Réactivité, Interactions et Spectroscopies (MONARIS)ParisFrance
| | - Christopher Dean
- Department of Earth Sciences, Centre for Human Evolution ResearchNatural History MuseumLondonUK,Department of Cell and Developmental BiologyUniversity College LondonLondonUK
| | - Smail Hadj‐Rabia
- Université Paris Cité, INSERM1163 Institut Imagine; APHP, Hôpital Necker‐Enfants Malades, Department of Dermatology, Reference Center for Rare Skin DiseasesParisFrance
| | - Pascal Houillier
- Université Paris Cité, Sorbonne Université, Centre de Recherche des Cordeliers, INSERM, CNRS‐ERL8228ParisFrance,APHP, Service de Physiologie, Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Hôpital Européen Georges PompidouParisFrance
| | - Tilman Breiderhoff
- Charité Universitaetsmedizin Berlin, Division of Gastroenterology, Nephrology and Metabolic Diseases, Department of PediatricsBerlinGermany
| | - Claire Bardet
- Université Paris Cité, URP2496 Pathologies, Imagerie et Biothérapies Orofaciales et Plateforme Imagerie du Vivant (PIV), FHU‐DDS‐net, IHMOA, Dental SchoolMontrougeFrance
| | - Thibaud Coradin
- Sorbonne Université, CNRS, Laboratoire de Chimie de la Matière Condensée de ParisParisFrance
| | - Fernando Ramirez Rozzi
- Université Paris Cité, URP2496 Pathologies, Imagerie et Biothérapies Orofaciales et Plateforme Imagerie du Vivant (PIV), FHU‐DDS‐net, IHMOA, Dental SchoolMontrougeFrance,Eco‐anthropologie (EA), Muséum national d'Histoire naturelle, CNRSUniversité de ParisParisFrance
| | - Catherine Chaussain
- Université Paris Cité, URP2496 Pathologies, Imagerie et Biothérapies Orofaciales et Plateforme Imagerie du Vivant (PIV), FHU‐DDS‐net, IHMOA, Dental SchoolMontrougeFrance,AP‐HP Services de médecine bucco‐dentaire, Hôpitaux Universitaires Bretonneau (CRMR phosphore et calcium, filière OSCAR et ERN Bond) and Charles Foix, FHU DDS‐netIle de FranceFrance
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4
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DeRocher KA, Smeets PJM, Goodge BH, Zachman MJ, Balachandran PV, Stegbauer L, Cohen MJ, Gordon LM, Rondinelli JM, Kourkoutis LF, Joester D. Chemical gradients in human enamel crystallites. Nature 2020; 583:66-71. [PMID: 32612224 PMCID: PMC8290891 DOI: 10.1038/s41586-020-2433-3] [Citation(s) in RCA: 84] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 04/08/2020] [Indexed: 11/16/2022]
Abstract
Dental enamel is a principal component of teeth1, and has evolved to bear large chewing forces, resist mechanical fatigue and withstand wear over decades2. Functional impairment and loss of dental enamel, caused by developmental defects or tooth decay (caries), affect health and quality of life, with associated costs to society3. Although the past decade has seen progress in our understanding of enamel formation (amelogenesis) and the functional properties of mature enamel, attempts to repair lesions in this material or to synthesize it in vitro have had limited success4-6. This is partly due to the highly hierarchical structure of enamel and additional complexities arising from chemical gradients7-9. Here we show, using atomic-scale quantitative imaging and correlative spectroscopies, that the nanoscale crystallites of hydroxylapatite (Ca5(PO4)3(OH)), which are the fundamental building blocks of enamel, comprise two nanometric layers enriched in magnesium flanking a core rich in sodium, fluoride and carbonate ions; this sandwich core is surrounded by a shell with lower concentration of substitutional defects. A mechanical model based on density functional theory calculations and X-ray diffraction data predicts that residual stresses arise because of the chemical gradients, in agreement with preferential dissolution of the crystallite core in acidic media. Furthermore, stresses may affect the mechanical resilience of enamel. The two additional layers of hierarchy suggest a possible new model for biological control over crystal growth during amelogenesis, and hint at implications for the preservation of biomarkers during tooth development.
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Affiliation(s)
- Karen A DeRocher
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Paul J M Smeets
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Berit H Goodge
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA
| | - Michael J Zachman
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Prasanna V Balachandran
- Department of Materials Science and Engineering, University of Virginia, Charlottesville, VA, USA
- Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, USA
| | - Linus Stegbauer
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Michael J Cohen
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Lyle M Gordon
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - James M Rondinelli
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Lena F Kourkoutis
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA
| | - Derk Joester
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, USA.
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5
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Asada Y, Chiba T, Shimoda S, Momoi Y, Yamamoto T. Acidic Calcium Phosphate Crystals Observed on the Outermost Layer of Human Enamel. J HARD TISSUE BIOL 2019. [DOI: 10.2485/jhtb.28.139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Yuka Asada
- Department of Operative Dentistry, Tsurumi University School of Dental Medicine
| | - Toshie Chiba
- Department of Oral Anatomy, Tsurumi University School of Dental Medicine
| | - Shinji Shimoda
- Department of Oral Anatomy, Tsurumi University School of Dental Medicine
| | - Yasuko Momoi
- Department of Operative Dentistry, Tsurumi University School of Dental Medicine
| | - Takatsugu Yamamoto
- Department of Operative Dentistry, Tsurumi University School of Dental Medicine
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6
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Tai Y, Asada Y, Chiba T, Miake Y, Shimoda S, Hosoya N. Electron Microscopic Study on the Formation of Hardened Molds of Calcium Phosphate Crystals Containing Gelatin. J HARD TISSUE BIOL 2019. [DOI: 10.2485/jhtb.28.165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Yasuharu Tai
- Department of Endodontology, Tsurumi University School of Dental Medicine
| | - Yuka Asada
- Department of Operative Dentistry, Tsurumi University School of Dental Medicine
| | - Toshie Chiba
- Department of Oral Anatomy, Tsurumi University School of Dental Medicine
| | - Yasuo Miake
- Department of Histology and Developmental Biology, Tokyo Dental College
| | - Shinji Shimoda
- Department of Oral Anatomy, Tsurumi University School of Dental Medicine
| | - Noriyasu Hosoya
- Department of Endodontology, Tsurumi University School of Dental Medicine
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7
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Lacruz RS, Habelitz S, Wright JT, Paine ML. DENTAL ENAMEL FORMATION AND IMPLICATIONS FOR ORAL HEALTH AND DISEASE. Physiol Rev 2017; 97:939-993. [PMID: 28468833 DOI: 10.1152/physrev.00030.2016] [Citation(s) in RCA: 223] [Impact Index Per Article: 31.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 01/10/2017] [Accepted: 01/10/2017] [Indexed: 12/16/2022] Open
Abstract
Dental enamel is the hardest and most mineralized tissue in extinct and extant vertebrate species and provides maximum durability that allows teeth to function as weapons and/or tools as well as for food processing. Enamel development and mineralization is an intricate process tightly regulated by cells of the enamel organ called ameloblasts. These heavily polarized cells form a monolayer around the developing enamel tissue and move as a single forming front in specified directions as they lay down a proteinaceous matrix that serves as a template for crystal growth. Ameloblasts maintain intercellular connections creating a semi-permeable barrier that at one end (basal/proximal) receives nutrients and ions from blood vessels, and at the opposite end (secretory/apical/distal) forms extracellular crystals within specified pH conditions. In this unique environment, ameloblasts orchestrate crystal growth via multiple cellular activities including modulating the transport of minerals and ions, pH regulation, proteolysis, and endocytosis. In many vertebrates, the bulk of the enamel tissue volume is first formed and subsequently mineralized by these same cells as they retransform their morphology and function. Cell death by apoptosis and regression are the fates of many ameloblasts following enamel maturation, and what cells remain of the enamel organ are shed during tooth eruption, or are incorporated into the tooth's epithelial attachment to the oral gingiva. In this review, we examine key aspects of dental enamel formation, from its developmental genesis to the ever-increasing wealth of data on the mechanisms mediating ionic transport, as well as the clinical outcomes resulting from abnormal ameloblast function.
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Affiliation(s)
- Rodrigo S Lacruz
- Department of Basic Science and Craniofacial Biology, College of Dentistry, New York University, New York, New York; Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, San Francisco, California; Department of Pediatric Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, North Carolina; Herman Ostrow School of Dentistry, Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, California
| | - Stefan Habelitz
- Department of Basic Science and Craniofacial Biology, College of Dentistry, New York University, New York, New York; Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, San Francisco, California; Department of Pediatric Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, North Carolina; Herman Ostrow School of Dentistry, Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, California
| | - J Timothy Wright
- Department of Basic Science and Craniofacial Biology, College of Dentistry, New York University, New York, New York; Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, San Francisco, California; Department of Pediatric Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, North Carolina; Herman Ostrow School of Dentistry, Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, California
| | - Michael L Paine
- Department of Basic Science and Craniofacial Biology, College of Dentistry, New York University, New York, New York; Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, San Francisco, California; Department of Pediatric Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, North Carolina; Herman Ostrow School of Dentistry, Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, California
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8
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Bronckers AL, Lyaruu DM. Magnesium, pH regulation and modulation by mouse ameloblasts exposed to fluoride. Bone 2017; 94:56-64. [PMID: 27744011 DOI: 10.1016/j.bone.2016.10.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 10/05/2016] [Accepted: 10/10/2016] [Indexed: 12/25/2022]
Abstract
Supraoptimal intake of fluoride (F) induces structural defects in forming enamel, dentin and bone and increases the risk of bone fractures. In comparison to bone and dentin is formation of enamel most sensitive to low levels of F and the degree of enamel fluorosis depends on the mouse strain. What molecular mechanism is responsible for these differences in sensitivity is unclear. Maturation ameloblasts transport bicarbonates into enamel in exchange for Cl- to buffer protons released by forming apatites. We proposed that F-enhanced mineral deposition releases excess of protons that will affect mineralization in forming enamel. In this study we tested the hypothesis that increased sensitivity to F is associated with a reduced capacity of ameloblasts to buffer acids. Quantified electron probe microanalysis showed that enamel of F-sensitive C57Bl mice contained the same levels of Cl- as enamel of F-resistant FVB mice. Enamel of C57Bl mice was less mineral dense, contained less Ca but more Mg and K. Ameloblast modulation was much more impaired than in FVB mice. In enamel of FVB mice the levels of Mg correlated negative with Ca (r=-0.57, p=0.01) and with the Ca/P molar ratio (r=-0.32, p=0.53). In moderate and high acidic enamel the correlations between Mg and Ca/P ratio were strong (r=-0.75, p=0.08) to very strong negative (r=-0.98, p=0.0020), respectively. Correlations in enamel between F and Ca were (weak) negative but between F and Ca/P very high positive (r=+0.95, p=0.003) in high acidic enamel and less positive (r=0.45, p=0.27) in moderate acidic fluorotic enamel (r=0.45, p=0.27). Similar correlations between Mg and Ca/P or F and Ca/P were found in dentin and bone of fluorotic and Cftr null mice. These data are consistent with the concept that Mg delays but F increases maturation of crystals particularly when enamel is acidic. The sensitivity of forming enamel to F likely is due to the sensitivity of pH cycling to acidification of enamel associated with F-induced release of protons.
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Affiliation(s)
- Antonius Ljj Bronckers
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, MOVE Research Institute, Amsterdam, The Netherlands.
| | - Donacian M Lyaruu
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, MOVE Research Institute, Amsterdam, The Netherlands
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9
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Abdallah MN, Eimar H, Bassett DC, Schnabel M, Ciobanu O, Nelea V, McKee MD, Cerruti M, Tamimi F. Diagenesis-inspired reaction of magnesium ions with surface enamel mineral modifies properties of human teeth. Acta Biomater 2016; 37:174-83. [PMID: 27060619 DOI: 10.1016/j.actbio.2016.04.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 03/09/2016] [Accepted: 04/06/2016] [Indexed: 11/18/2022]
Abstract
UNLABELLED Mineralized tissues such as teeth and bones consist primarily of highly organized apatitic calcium-phosphate crystallites within a complex organic matrix. The dimensions and organization of these apatite crystallites at the nanoscale level determine in part the physical properties of mineralized tissues. After death, geological processes such as diagenesis and dolomitization can alter the crystallographic properties of mineralized tissues through cycles of dissolution and re-precipitation occurring in highly saline environments. Inspired by these natural exchange phenomena, we investigated the effect of hypersalinity on tooth enamel. We discovered that magnesium ions reacted with human tooth enamel through a process of dissolution and re-precipitation, reducing enamel crystal size at the surface of the tooth. This change in crystallographic structure made the teeth harder and whiter. Salt-water rinses have been used for centuries to ameliorate oral infections; however, our discovery suggests that this ancient practice could have additional unexpected benefits. STATEMENT OF SIGNIFICANCE Here we describe an approach inspired by natural geological processes to modify the properties of a biomineral - human tooth enamel. In this study we showed that treatment of human tooth enamel with solutions saturated with magnesium induced changes in the nanocrystals at the outer surface of the protective enamel layer. As a consequence, the physical properties of the tooth were modified; tooth microhardness increased and the color shade became whiter, thus suggesting that this method could be used as a clinical treatment to improve dental mechanical properties and esthetics. Such an approach is simple and straightforward, and could also be used to develop new strategies to synthesize and modify biominerals for biomedical and industrial applications.
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Affiliation(s)
| | - Hazem Eimar
- Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada
| | - David C Bassett
- Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada
| | - Martin Schnabel
- Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada
| | - Ovidiu Ciobanu
- Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada
| | - Valentin Nelea
- Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada
| | - Marc D McKee
- Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada; Department of Anatomy and Cell Biology, Faculty of Medicine, McGill University, H3A 0C7 Montreal, QC, Canada
| | - Marta Cerruti
- Department of Mining and Materials Engineering, McGill University, H3A 0E8 Montreal, QC, Canada
| | - Faleh Tamimi
- Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada.
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10
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Dosedělová H, Štěpánková K, Zikmund T, Lesot H, Kaiser J, Novotný K, Štembírek J, Knotek Z, Zahradníček O, Buchtová M. Age-related changes in the tooth-bone interface area of acrodont dentition in the chameleon. J Anat 2016; 229:356-68. [PMID: 27173578 DOI: 10.1111/joa.12490] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/06/2016] [Indexed: 11/29/2022] Open
Abstract
Chameleon teeth develop as individual structures at a distance from the developing jaw bone during the pre-hatching period and also partially during the post-hatching period. However, in the adult, all teeth are fused together and tightly attached to the jaw bone by mineralized attachment tissue to form one functional unit. Tooth to bone as well as tooth to tooth attachments are so firm that if injury to the oral cavity occurs, several neighbouring teeth and pieces of jaw can be broken off. We analysed age-related changes in chameleon acrodont dentition, where ankylosis represents a physiological condition, whereas in mammals, ankylosis only occurs in a pathological context. The changes in hard-tissue morphology and mineral composition leading to this fusion were analysed. For this purpose, the lower jaws of chameleons were investigated using X-ray micro-computed tomography, laser-induced breakdown spectroscopy and microprobe analysis. For a long time, the dental pulp cavity remained connected with neighbouring teeth and also to the underlying bone marrow cavity. Then, a progressive filling of the dental pulp cavity by a mineralized matrix occurred, and a complex network of non-mineralized channels remained. The size of these unmineralized channels progressively decreased until they completely disappeared, and the dental pulp cavity was filled by a mineralized matrix over time. Moreover, the distribution of calcium, phosphorus and magnesium showed distinct patterns in the different regions of the tooth-bone interface, with a significant progression of mineralization in dentin as well as in the supporting bone. In conclusion, tooth-bone fusion in chameleons results from an enhanced production of mineralized tissue during post-hatching development. Uncovering the developmental processes underlying these outcomes and performing comparative studies is necessary to better understand physiological ankylosis; for that purpose, the chameleon can serve as a useful model species.
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Affiliation(s)
- Hana Dosedělová
- Department of Anatomy, Histology and Embryology, University of Veterinary and Pharmaceutical Sciences Brno, Brno, Czech Republic.,Institute of Animal Physiology and Genetics, v.v.i., Academy of Sciences of the Czech Republic, Brno, Czech Republic
| | - Kateřina Štěpánková
- Department of Chemistry, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Tomáš Zikmund
- CEITEC - Central European Institute of Technology, Brno, University of Technology, Brno , Czech Republic
| | - Herve Lesot
- INSERM (French National Institute of Health and Medical Research), 'Osteoarticular and Dental Regenerative NanoMedicine' Laboratory, Faculté de Médicine, Université de Strasbourg, UMR 1109, Strasbourg, France.,Faculté de Chirurgie Dentaire, Université de Strasbourg, Strasbourg, France
| | - Jozef Kaiser
- CEITEC - Central European Institute of Technology, Brno, University of Technology, Brno , Czech Republic
| | - Karel Novotný
- Department of Chemistry, Faculty of Science, Masaryk University, Brno, Czech Republic.,CEITEC - Central European Institute of Technology, Brno, University of Technology, Brno , Czech Republic
| | - Jan Štembírek
- Institute of Animal Physiology and Genetics, v.v.i., Academy of Sciences of the Czech Republic, Brno, Czech Republic.,Department of Oral and Maxillofacial Surgery, University Hospital Ostrava, Ostrava, Czech Republic
| | - Zdeněk Knotek
- Clinic of Small Animals, University of Veterinary and Pharmaceutical Sciences Brno, Brno, Czech Republic
| | - Oldřich Zahradníček
- Department of Teratology, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Marcela Buchtová
- Institute of Animal Physiology and Genetics, v.v.i., Academy of Sciences of the Czech Republic, Brno, Czech Republic.,Department of Experimental Biology, Masaryk University, Brno, Czech Republic
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Bronckers ALJJ, Lyaruu D, Jalali R, Medina JF, Zandieh-Doulabi B, DenBesten PK. Ameloblast Modulation and Transport of Cl⁻, Na⁺, and K⁺ during Amelogenesis. J Dent Res 2015; 94:1740-7. [PMID: 26403673 DOI: 10.1177/0022034515606900] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Ameloblasts express transmembrane proteins for transport of mineral ions and regulation of pH in the enamel space. Two major transporters recently identified in ameloblasts are the Na(+)K(+)-dependent calcium transporter NCKX4 and the Na(+)-dependent HPO4 (2-) (Pi) cotransporter NaPi-2b. To regulate pH, ameloblasts express anion exchanger 2 (Ae2a,b), chloride channel Cftr, and amelogenins that can bind protons. Exposure to fluoride or null mutation of Cftr, Ae2a,b, or Amelx each results in formation of hypomineralized enamel. We hypothesized that enamel hypomineralization associated with disturbed pH regulation results from reduced ion transport by NCKX4 and NaPi-2b. This was tested by correlation analyses among the levels of Ca, Pi, Cl, Na, and K in forming enamel of mice with null mutation of Cftr, Ae2a,b, and Amelx, according to quantitative x-ray electron probe microanalysis. Immunohistochemistry, polymerase chain reaction analysis, and Western blotting confirmed the presence of apical NaPi-2b and Nckx4 in maturation-stage ameloblasts. In wild-type mice, K levels in enamel were negatively correlated with Ca and Cl but less negatively or even positively in fluorotic enamel. Na did not correlate with P or Ca in enamel of wild-type mice but showed strong positive correlation in fluorotic and nonfluorotic Ae2a,b- and Cftr-null enamel. In hypomineralizing enamel of all models tested, 1) Cl(-) was strongly reduced; 2) K(+) and Na(+) accumulated (Na(+) not in Amelx-null enamel); and 3) modulation was delayed or blocked. These results suggest that a Na(+)K(+)-dependent calcium transporter (likely NCKX4) and a Na(+)-dependent Pi transporter (potentially NaPi-2b) located in ruffle-ended ameloblasts operate in a coordinated way with the pH-regulating machinery to transport Ca(2+), Pi, and bicarbonate into maturation-stage enamel. Acidification and/or associated physicochemical/electrochemical changes in ion levels in enamel fluid near the apical ameloblast membrane may reduce the transport activity of mineral transporters, which results in hypomineralization.
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Affiliation(s)
- A L J J Bronckers
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam, University of Amsterdam, and MOVE Research Institute, VU University Amsterdam, Amsterdam, Netherlands
| | - D Lyaruu
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam, University of Amsterdam, and MOVE Research Institute, VU University Amsterdam, Amsterdam, Netherlands
| | - R Jalali
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam, University of Amsterdam, and MOVE Research Institute, VU University Amsterdam, Amsterdam, Netherlands
| | - J F Medina
- Division of Gene Therapy and Hepatology, School of Medicine/CIMA, University of Navarra, and CIBERehd, Pamplona, Spain
| | - B Zandieh-Doulabi
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam, University of Amsterdam, and MOVE Research Institute, VU University Amsterdam, Amsterdam, Netherlands
| | - P K DenBesten
- Department of Oral Sciences, University of California, San Francisco, CA, USA
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12
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Kurata S, Sato K, Kanri Y, Aoba T. Solubility Properties of Carbonatoapatites with Discrete Stoichiometric Compositions. J Oral Biosci 2006. [DOI: 10.1016/s1349-0079(06)80024-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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13
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Abstract
Dental research over the last century has advanced our understanding of the etiology and pathogenesis of caries lesions. Increasing knowledge of the dynamic demineralization/remineralization processes has led to the current consensus that bacteria-mediated tooth destruction can be arrested or even to some degree reversed by adopting fluoride and other preventive measures without using restorative materials. Our experimental approach provided new insight into the stoichiometries and solubility properties of human enamel and dentin mineral. The determination of the solubility product constant on the basis of the stoichiometric model (Ca)5.x(Mg)q(Na)u(HPO4)v(CO3)w(PO4)3.y(OH,F)1.z, verifies the difference in their solubility properties, supporting the phase transformation between tooth mineral and calcium phosphates in a wide range of fluid compositions as found in the oral environment. Further refinement of the stoichiometry and solubility parameters is essential to assess quantitatively the driving force for de- and remineralization of enamel and dentin in the oral fluid environment. Prediction of the effects of a combination of inhibitors and accelerator(s) on remineralization kinetics is also required. In order to develop devices efficient for optimizing remineralization in the lesion body, it is a critical question how, and to what extent, fluoride can compensate for the activity of any inhibitors in the mineralizing media.
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Affiliation(s)
- T Aoba
- Department of Pathology, The Nippon Dental University, Tokyo, Japan.
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14
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Jibiki M, Shimoda S, Nakagawa Y, Kawasaki K, Asada K, Ishibashi K. Calcifications of the disc of the temporomandibular joint. J Oral Pathol Med 1999; 28:413-9. [PMID: 10535365 DOI: 10.1111/j.1600-0714.1999.tb02113.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Calcified lesions of the temporomandibular joint discs obtained from 135 human cadavers were studied. Calcifications were observed in 92 of 250 discs by soft x-ray radiography. Studies by light and electron microscopy and x-ray diffraction revealed that there were two different types of calcification in the discs: apatite crystal deposition with or without ossification, and calcium pyrophosphate dehydrate (CPPD) crystal deposition. Calcifications were recognized more frequently posteriorly than anteriorly, and were related to disc perforation. The results of this investigation suggest that disc degeneration, which may occur as a result of aging or mechanical stress, causes calcifications.
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Affiliation(s)
- M Jibiki
- The Second Department of Oral and Maxillofacial Surgery, Tsurumi University, School of Dental Medicine, Yokohama, Japan
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15
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Rohanizadeh R, Pouëzat J, Bohne W, Ajacques JC. Ultrastructural organization and microanalysis studies of deciduous enamel crystallites in regional odontodysplasia (RO). J Oral Pathol Med 1998; 27:501-7. [PMID: 9831964 DOI: 10.1111/j.1600-0714.1998.tb01920.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The ultrastructural organization and chemical components of enamel crystallites in two deciduous teeth affected by RO, an uncommon developmental condition giving the tooth a ghost-like appearance, were investigated by scanning and transmission electron microscopy, X-ray diffraction, electron probe microanalysis and Fourier transform improved microspectroscopy. Pathologic mineralizations involving prismatic structures, which affected the size, shape and stoichiometric structure of crystallites and led to enhanced Mg/Ca and Na/Ca ratios and crystal defects, were observed. Local circulatory disorders may have caused this developmental anomaly.
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Affiliation(s)
- R Rohanizadeh
- Laboratoire de Recherches sur les Tissus Calcifiés et les Biomatériaux, University of Nantes, France
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16
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Aoba T. The effect of fluoride on apatite structure and growth. CRITICAL REVIEWS IN ORAL BIOLOGY AND MEDICINE : AN OFFICIAL PUBLICATION OF THE AMERICAN ASSOCIATION OF ORAL BIOLOGISTS 1997; 8:136-53. [PMID: 9167089 DOI: 10.1177/10454411970080020301] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Fluoride participates in many aspects of calcium phosphate formation in vivo and has enormous effects on the process and on the nature and properties of formed mineral. The most well-documented effect of fluoride is that this ion substitutes for a column hydroxyl in the apatite structure, giving rise to a reduction of crystal volume and a concomitant increase in structural stability. In the process of enamel mineralization during amelogenesis (a unique model for the cell-mediated formation of well-crystallized carbonatoapatite), free fluoride ions in the fluid phase are supposed to accelerate the hydrolysis of acidic precursor(s) and increase the driving force for the growth of apatitic mineral. Once fluoride is incorporated into the enamel mineral, the ion likely affects the subsequent mineralization process by reducing the solubility of the mineral and thereby modulating the ionic composition in the fluid surrounding the mineral, and enhancing the matrix protein-mineral interaction. But excess fluoride leads to anomalous enamel formation by retarding tissue maturation. It is worth noting that enameloid/enamel minerals found in vertebrate teeth have a wide range of CO3 and fluoride substitutions. In the evolutionary process from elasmobranch through enameloid to mammalian enamel, the biosystems appear to develop regulatory functions for limiting the fluoridation of the formed mineral, but this development is accompanied by an increase of carbonate substitution or defects in the mineral. In research on the cariostatic effect of fluoride, considerable emphasis is placed on the roles of free fluoride ions (i.e., preventing the dissolution and accelerating the kinetics of remineralization) in the oral fluid bathing tooth mineral. Fluoride also has been used for the treatment of osteoporosis, but much still remains to be learned about maximizing the benefit and minimizing the risk of fluoride when used as a public health measure.
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Affiliation(s)
- T Aoba
- Nippon Dental University, Department of Pathology, Tokyo, Japan
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17
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Abstract
BACKGROUND Enamel mineralization taking place during amelogenesis is a unique model to investigate carbonatoapatite formation in vivo. The abundance of proteinaceous crystal growth inhibitors, in particular amelogenins, contributes significantly to the mineralization process. Their putative roles are to prevent random proliferation of crystal nuclei and to regulate the growth kinetics and orientation of the formed enamel crystals. METHODS The enamel fluid surrounding the forming enamel crystals contains high concentrations of carbonate and magnesium ions, both of which seem to modulate the mineralization process. Particularly, Mg ions can adsorb onto enamel crystal surfaces in a manner to compete with Ca ions. Enamel mineral formed during amelogenesis is featured as calcium-deficient, acid phosphate-rich carbonatoapatites. Currently the most putative stoichiometry model for enamel mineral is (Ca)5-x(HPO4)v(CO3)w(PO4)3-x (OH)1-x. RESULTS Very significant changes in the morphology, stoichiometry, and solubility of enamel crystals occur during the various stages of amelogenesis. The early enamel mineralization comprises two events: the initial precipitation of the well-documented thin ribbons and the subsequent overgrowth of apatite crystals on those templates. The thin ribbons precipitated in the vicinity of the secretory ameloblasts have the highest contents of acid phosphate, particularly in the form of exchangeable species, whereas both the exchangeable and unexchangeable acid phosphate decrease concomitantly with the progress of the apatite overgrowth and the appearance of elongated hexagonal crystals in the late secretory stages. CONCLUSIONS Those morphological and compositional features seem to be consistent with the formation of precursors, such as octacalcium phosphate.
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Affiliation(s)
- T Aoba
- Department of Pathology, Nippon Dental University, Tokyo, Japan
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18
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Simmer JP, Fincham AG. Molecular mechanisms of dental enamel formation. CRITICAL REVIEWS IN ORAL BIOLOGY AND MEDICINE : AN OFFICIAL PUBLICATION OF THE AMERICAN ASSOCIATION OF ORAL BIOLOGISTS 1995; 6:84-108. [PMID: 7548623 DOI: 10.1177/10454411950060020701] [Citation(s) in RCA: 316] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Tooth enamel is a unique mineralized tissue in that it is acellular, is more highly mineralized, and is comprised of individual crystallites that are larger and more oriented than other mineralized tissues. Dental enamel forms by matrix-mediated biomineralization. Enamel crystallites precipitate from a supersaturated solution within a well-delineated biological compartment. Mature enamel crystallites are comprised of non-stoichiometric carbonated calcium hydroxyapatite. The earliest crystallites appear suddenly at the dentino-enamel junction (DEJ) as rapidly growing thin ribbons. The shape and growth patterns of these crystallites can be interpreted as evidence for a precursor phase of octacalcium phosphate (OCP). An OCP crystal displays on its (100) face a surface that may act as a template for hydroxyapatite (OHAp) precipitation. Octacalcium phosphate is less stable than hydroxyapatite and can hydrolyze to OHAp. During this process, one unit cell of octacalcium phosphate is converted into two unit cells of hydroxyapatite. During the precipitation of the mineral phase, the degree of saturation of the enamel fluid is regulated. Proteins in the enamel matrix may buffer calcium and hydrogen ion concentrations as a strategy to preclude the precipitation of competing calcium phosphate solid phases. Tuftelin is an acidic enamel protein that concentrates at the DEJ and may participate in the nucleation of enamel crystals. Other enamel proteins may regulate crystal habit by binding to specific faces of the mineral and inhibiting growth. Structural analyses of recombinant amelogenin are consistent with a functional role in establishing and maintaining the spacing between enamel crystallites.
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Affiliation(s)
- J P Simmer
- University of Texas School of Dentistry, Health Science Center at San Antonio, Department of Pediatric Dentistry 78284-7888, USA
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19
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Aoba T. Strategies for improving the assessment of dental fluorosis: focus on chemical and biochemical aspects. Adv Dent Res 1994; 8:66-74. [PMID: 7993562 DOI: 10.1177/08959374940080011201] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In order to assess fluoride accumulation and effects in developing dental tissues, one must determine the concentration profile of fluoride in the tissue and to assess separately the labile (i.e., free ions in fluid and ions associated with organic matter) and stable (i.e., incorporated into apatite lattice) pools of fluoride. Free fluoride ions in the mineralizing milieu markedly affect the driving force for precipitation and, as a result, the nature of precipitating crystals. The fluoride incorporated into the crystalline lattice increases the stability of the formed mineral. Improvement in the understanding of the mechanism of dental fluorosis requires more comprehensive information about the effects of fluoride on the ionic composition of the fluid phase, the nature of the initially precipitating mineral(s), the interactions between crystals and matrix proteins, and the enzymatic degradation of the proteins. Recent observations relevant to the role of fluoride in enamel formation include: (1) that there are threshold concentrations of fluoride below which the precipitation and hydrolysis of thin-platy octacalcium phosphate is facilitated but beyond which de novo apatite precipitation prevails; (2) that the presence of fluoride in the mineralizing milieu most likely affects the steady-state concentrations of mineral lattice ions; (3) that incorporation of fluoride into the stable pool is retarded by the presence of matrix proteins, particularly amelogenins, which inhibit the growth of apatite crystals; (4) that increasing the degree of fluoridation of apatite crystals enhances the adsorption of amelogenins onto the crystal surface, and (5) that amelogenins pre-adsorbed onto apatite crystals are more resistant to enzymatic cleavages by trypsin (used as a prototype of amelogeninases).
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Affiliation(s)
- T Aoba
- Nippon Dental University, Department of Pathology, Tokyo, Japan
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