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Chun YHP, Tan C, Villanueva O, Colley ME, Quintanilla TJ, Basiouny MS, Hartel CA, Critchfield CS, Bach SBH, Fajardo RJ, Pham CD. Overexpression of ameloblastin in secretory ameloblasts results in demarcated, hypomineralized opacities in enamel. Front Physiol 2024; 14:1233391. [PMID: 38274050 PMCID: PMC10808694 DOI: 10.3389/fphys.2023.1233391] [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: 06/02/2023] [Accepted: 11/01/2023] [Indexed: 01/27/2024] Open
Abstract
Introduction: Developmental defects of the enamel manifest before tooth eruption and include amelogenesis imperfecta, a rare disease of underlying gene mutations, and molar-incisor hypomineralization (MIH), a prevalent disease in children originating from environmental and epigenetic factors. MIH enamel presents as the abnormal enamel marked by loss of translucency, demarcation between the healthy and affected enamel, and reduced mineral content. The pathophysiology of opaque, demarcated enamel lesions is not understood; however, the retention of enamel proteins in the matrix has been suggested. Ameloblastin (Ambn) is an enamel protein of the secreted calcium-binding phosphoproteins (SCPPs) critical for enamel formation. When the Ambn gene is mutated or deleted, teeth are affected by hypoplastic amelogenesis imperfecta. Methods: In this study, enamel formation in mice was analyzed when transgenic Ambn was overexpressed from the amelogenin promoter encoding full-length Ambn. Ambn was under- and overexpressed at six increasing concentrations in separate mouse lines. Results: Mice overexpressing Ambn displayed opaque enamel at low concentrations and demarcated lesions at high concentrations. The severity of enamel lesions increased starting from the inner enamel close to the dentino-enamel junction (DEJ) to span the entire width of the enamel layer in demarcated areas. Associated with the opaque enamel were 17-kDa Ambn cleavage products, a prolonged secretory stage, and a thin basement membrane in the maturation stage. Ambn accumulations found in the innermost enamel close to the DEJ and the mineralization front correlated with reduced mineral content. Demarcated enamel lesions were associated with Ambn species of 17 kDa and higher, prolonged secretory and transition stages, a thin basement membrane, and shortened maturation stages. Hypomineralized opacities were delineated against the surrounding mineralized enamel and adjacent to ameloblasts detached from the enamel surface. Inefficient Ambn cleavage, loss of contact between ameloblasts, and the altered basement membrane curtailed the endocytic activity; thus, enamel proteins remained unresorbed in the matrix. Ameloblasts have the ability to distinguish between Ambn concentration and Ambn cleavage products through finely tuned feedback mechanisms. The under- or overexpression of Ambn in murine secretory ameloblasts results in either hypoplastic amelogenesis imperfecta or hypomineralization with opaque or sharply demarcated boundaries of lesions, similar to MIH.
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Affiliation(s)
- Yong-Hee Patricia Chun
- Department of Periodontics, School of Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
- Department of Cell Systems and Anatomy, School of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
- Department of Molecular Medicine, School of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Chunyan Tan
- Department of Periodontics, School of Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Omar Villanueva
- Department of Periodontics, School of Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Madeline E. Colley
- Department of Chemistry, University of Texas San Antonio, San Antonio, TX, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
- Mass Spectrometry Research Center, Vanderbilt University, Nashville, TN, United States
| | - Travis J. Quintanilla
- Department of Periodontics, School of Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Mohamed S. Basiouny
- Department of Periodontics, School of Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Caldonia A. Hartel
- Department of Periodontics, School of Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Cameron S. Critchfield
- Department of Periodontics, School of Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Stephan B. H. Bach
- Department of Chemistry, University of Texas San Antonio, San Antonio, TX, United States
| | - Roberto J. Fajardo
- Department of Clinical and Applied Science Education, School of Osteopathic Medicine, University of the Incarnate Word, San Antonio, TX, United States
| | - Cong-Dat Pham
- Department of Periodontics, School of Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, TX, United States
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Xu C, Wang A, Zhang L, Yang C, Gao Y, Dong Z, Tian Y, Li C, Gao Y. Epithelium-Specific Runx2 knockout mice display junctional epithelium and alveolar bone defects. Oral Dis 2020; 27:1292-1299. [PMID: 32946165 DOI: 10.1111/odi.13647] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 08/31/2020] [Accepted: 09/10/2020] [Indexed: 12/13/2022]
Abstract
OBJECTIVE The aim of this investigation was to study the effects of Runt-related transcription factor 2 (Runx2) on the junctional epithelium and alveolar bone. METHODS The attachment level of the junctional epithelium and the resorption of alveolar bone were analyzed by histology and scanning electron microscopy. The expression of amelotin was determined by immunohistochemistry, Western blot, and real-time PCR. The ultrastructure of the dentogingival interface was observed by transmission electron microscopy. RESULTS The cKO mice demonstrated remarkable attachment loss, epithelial hyperplasia, and alveolar bone loss. The relative protein and mRNA expression of amelotin was increased in the junctional epithelium of the cKO mice. The attachment apparatus of the cKO mice showed ultrastructural deficiency. CONCLUSIONS Loss of Runx2 led to the junctional epithelium and alveolar bone defects in mice. Runx2 may play a crucial role in maintaining the integrity of the dentogingival junction and the normal structure of alveolar bone.
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Affiliation(s)
- Chang Xu
- Department of Pediatric Dentistry, Binzhou Medical University Hospital, Binzhou, China
| | - Aiqin Wang
- Department of Periodontics, Binzhou Medical University Hospital, Binzhou, China
| | - Li Zhang
- Institute of Stomatology, Binzhou Medical University, Yantai, China
| | - Chunyan Yang
- Institute of Stomatology, Binzhou Medical University, Yantai, China
| | - Yan Gao
- Department of Pediatric Dentistry, Binzhou Medical University Hospital, Binzhou, China
| | - Zhiheng Dong
- Department of Pediatric Dentistry, Binzhou Medical University Hospital, Binzhou, China
| | - Yuan Tian
- Institute of Stomatology, Binzhou Medical University, Yantai, China
| | - Cong Li
- Institute of Stomatology, Binzhou Medical University, Yantai, China
| | - Yuguang Gao
- Department of Pediatric Dentistry, Binzhou Medical University Hospital, Binzhou, China
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Sugawara S, Maeno M, Lee C, Nagai S, Kim DM, Da Silva J, Nagai M, Kondo H. Establishment of Epithelial Attachment on Titanium Surface Coated with Platelet Activating Peptide. PLoS One 2016; 11:e0164693. [PMID: 27741287 PMCID: PMC5065151 DOI: 10.1371/journal.pone.0164693] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/29/2016] [Indexed: 11/19/2022] Open
Abstract
The aim of this study was to produce epithelial attachment on a typical implant abutment surface of smooth titanium. A challenging complication that hinders the success of dental implants is peri-implantitis. A common cause of peri-implantitis may results from the lack of epithelial sealing at the peri-implant collar. Histologically, epithelial sealing is recognized as the attachment of the basement membrane (BM). BM-attachment is promoted by activated platelet aggregates at surgical wound sites. On the other hand, platelets did not aggregate on smooth titanium, the surface typical of the implant abutment. We then hypothesized that epithelial BM-attachment was produced when titanium surface was modified to allow platelet aggregation. Titanium surfaces were coated with a protease activated receptor 4-activating peptide (PAR4-AP). PAR4-AP coating yielded rapid aggregation of platelets on the titanium surface. Platelet aggregates released robust amount of epithelial chemoattractants (IGF-I, TGF-β) and growth factors (EGF, VEGF) on the titanium surface. Human gingival epithelial cells, when they were co-cultured on the platelet aggregates, successfully attached to the PAR4-AP coated titanium surface with spread laminin5 positive BM and consecutive staining of the epithelial tight junction component ZO1, indicating the formation of complete epithelial sheet. These in-vitro results indicate the establishment of epithelial BM-attachment to the titanium surface.
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Affiliation(s)
- Shiho Sugawara
- Department of Restorative Dentistry and Biomaterials Sciences, Harvard School of Dental Medicine, Boston, Massachusetts, United States of America
- Department of Prosthodontics and Oral Implantology, Iwate Medical University, School of Dental Medicine, Morioka, Iwate, Japan
| | - Masahiko Maeno
- Department of Restorative Dentistry and Biomaterials Sciences, Harvard School of Dental Medicine, Boston, Massachusetts, United States of America
- Department of Adhesive Dentistry, The Nippon Dental University, Chiyoda-ku, Tokyo, Japan
| | - Cliff Lee
- Department of Restorative Dentistry and Biomaterials Sciences, Harvard School of Dental Medicine, Boston, Massachusetts, United States of America
| | - Shigemi Nagai
- Department of Restorative Dentistry and Biomaterials Sciences, Harvard School of Dental Medicine, Boston, Massachusetts, United States of America
| | - David M. Kim
- Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, United States of America
| | - John Da Silva
- Department of Restorative Dentistry and Biomaterials Sciences, Harvard School of Dental Medicine, Boston, Massachusetts, United States of America
| | - Masazumi Nagai
- Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, United States of America
| | - Hisatomo Kondo
- Department of Prosthodontics and Oral Implantology, Iwate Medical University, School of Dental Medicine, Morioka, Iwate, Japan
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Sawada T, Yamazaki T, Shibayama K, Yamaguchi Y, Ohshima M. Ultrastructural immunolocalization of laminin 332 (laminin 5) at dento-gingival interface in Macaca fuscata monkey. Med Mol Morphol 2015; 48:104-11. [PMID: 25055992 DOI: 10.1007/s00795-014-0085-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 06/18/2014] [Indexed: 10/25/2022]
Abstract
Although laminin 332 (laminin 5), an extracellular matrix molecule involved in cell adhesion and migration, has been localized at the interface between the tooth enamel and junctional epithelium, its ultrastructural localization remains to be fully clarified. The purpose of the present study was to investigate the ultrastructural distribution of laminin 332 at the dento-gingival interface in Japanese monkey (Macaca fuscata) using pre- and post-embedding immunoelectron microscopy. Pre-embedding immunoelectron microscopy revealed a broad band of internal basal lamina together with supplementary lamina densa, and both showed immunolabeling for laminin 332. Immunoreaction products for laminin 332 were observed in the rough-surfaced endoplasmic reticulum of the junctional epithelial cells close to the tooth enamel. Post-embedding immunoelectron microscopy revealed an increase in the number of immunogold particles toward the coronal portion, resulting in a large accumulation of particles on the basal lamina, preferentially on the lamina densa. Concomitantly the dental cuticle at the dento-gingival interface was sporadically, but specifically, immunogold-labeled with anti-laminin 332 antibody. These data suggest that junctional epithelium actively produces laminin 332, and that the products accumulate at the dento-gingival interface during cell migration coronally towards the gingival sulcus.
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Affiliation(s)
- Takashi Sawada
- Department of Histology and Developmental Biology, Tokyo Dental College, 2-9-18 Misaki-cho, Chiyoda-ku, Tokyo, 101-0061, Japan,
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Sawada T, Yamazaki T, Shibayama K, Kumazawa K, Yamaguchi Y, Ohshima M. Expression and localization of laminin 5, laminin 10, type IV collagen, and amelotin in adult murine gingiva. J Mol Histol 2014; 45:293-302. [PMID: 24338356 DOI: 10.1007/s10735-013-9559-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 12/02/2013] [Indexed: 10/25/2022]
Abstract
The biochemical composition of the internal and external basal laminae in the junctional epithelium differs significantly, and the precise cellular origin of their respective molecules remains to be determined. In the present study, the expression and localization of three basement membrane-specific molecules-laminin 5 (γ2 chain), type IV collagen (α1 chain), and laminin 10 (α5 chain)-and one tooth-specific molecule, amelotin, was analyzed in adult murine gingiva by using in situ hybridization and immunohistochemistry. The results showed that the outermost cells in junctional epithelium facing the tooth enamel strongly expressed laminin 5 mRNA, supporting the immunohistochemical staining data. This suggests that laminin 5 is actively synthesized in junctional epithelial cells and that the products are incorporated into the internal basal lamina to maintain firm epithelial adhesion to the tooth enamel throughout life. Conversely, no amelotin mRNA signals were detected in the junctional epithelial cells, suggesting that the molecules localized on the internal basal lamina are mainly derived from maturation-stage ameloblasts. Weak and sporadic expression of type IV collagen in addition to laminin 10 in the gingiva indicates that these molecules undergo turnover less frequently in adult animals.
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Affiliation(s)
- Takashi Sawada
- Department of Ultrastructural Science, Tokyo Dental College, Misaki-cho 2-9-18, Chiyoda-ku, Tokyo, 101-0061, Japan,
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Shioya K, Sawada T, Miake Y, Inoue S, Yanagisawa T. Ultrastructural study of tissues surrounding replanted teeth and dental implants. Clin Oral Implants Res 2009; 20:299-305. [DOI: 10.1111/j.1600-0501.2008.01644.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Ishikawa H, Hashimoto S, Tanno M, Ishikawa T, Tanaka T, Shimono M. Cytoskeleton and surface structures of cells directly attached to the tooth in the rat junctional epithelium. J Periodontal Res 2005; 40:354-63. [PMID: 15966914 DOI: 10.1111/j.1600-0765.2005.00815.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE It is still an open question whether cells directly attached to the tooth (DAT) cells are migratory or non-migratory cells. The purpose of this study was to examine cytoskeletal and surface structures of DAT cells that might be involved in migration. METHODS We investigated the distribution of stress fibers composed of actin filaments in DAT cells using phallacidin fluorescent dye methods in a confocal laser scanning microscope. To observe the three-dimensional structure of the DAT cell surface, the osmium maceration scanning electron microscope (SEM) method, which removes various soluble materials between DAT cells and the enamel, was employed. RESULTS Stress fibers were found in the most apically located DAT cells, and were arranged in parallel to the presumable cervical-line, whereas some of the fibers ran parallel to the tooth axis in the more coronally located DAT cells. The parallel arrangement to the tooth axis of the fibers may be involved with migration for turnover, and the parallel accumulation to the presumable cervical-line may be concerned with the cervical contraction of DAT cells. Osmium maceration SEM images at high magnification revealed the existence of microvilli-like structures on the enamel surfaces (facing to the tooth surface) of DAT cells after removal of the soluble matrices. The thicknesses of the microvilli-like structures on the enamel surfaces and cell processes of intercellular bridges were significantly different. CONCLUSION DAT cells possess stress fibers arranged in parallel to the tooth axis and to the presumable cervical-line in the cytoplasm, and microvilli-like structures on their enamel surfaces. These results suggest that these structures contribute to DAT cell migration.
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Inoue S, Reinisch C, Tschachler E, Eckhart L. Ultrastructural characterization of an artificial basement membrane produced by cultured keratinocytes. J Biomed Mater Res A 2005; 73:158-64. [PMID: 15754320 DOI: 10.1002/jbm.a.30285] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A recent study in our laboratories on the growth of keratinocytes at the culture medium/air interface has led to the identification of a novel thin sheet-like matrix that supports adherent cells. This novel matrix consists of components secreted by keratinocytes, including type IV collagen, and laminins 1 and 5, that self-assembled to a membrane structure. In the present study, a detailed ultrastructural characterization of this membrane was done with high-resolution electron microscopy after negative staining. The basic organization of the membrane was found to be a dense network of 8- to 10-nm-wide irregular rod-like elements. High-resolution examination and immunolabeling showed that type IV collagen filaments form the core of these elements, and other components including heparan sulfate proteoglycan in the form of 4.5- to 5-nm-wide ribbon-like "double tracks" are aggregated around it. These detailed features of the membrane strikingly resembled those of the basement membrane in vivo. These ultrastructural similarities indicate that the membrane may also have basement membrane-like functional properties, and suggest that it should be considered for testing in future medical applications.
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Affiliation(s)
- Sadayuki Inoue
- Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montreal, Quebec, Canada.
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10
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Abstract
BACKGROUND The dento-epithelial junction forms the primary periodontal defense structure against oral microbes. The cells of the junctional epithelium (JE) attach both to a basement membrane (BM) facing the connective tissue and to a hard dental tissue by structurally similar but molecularly distinct mechanisms. Here we describe a new organotypic cell culture model for the dento-epithelial junction comprising not only epithelial and mesenchymally derived components, but also a tooth surface equivalent. METHODS Rat palatal keratinocytes were seeded on fibroblast-collagen gels. A tooth slice was placed on top of the epithelial cells and the multilayer cultures were grown at the air-liquid interface. Formation of the epithelial structures, BM components, and the epithelial attachment to the tooth surface were studied by immunofluorescence and light and electron microscopy. The findings were compared to the structure of the dento-epithelial junction in vivo. RESULTS A well-differentiated stratified epithelium was formed. Under the tooth slice the epithelium remained thin and non-differentiated. Attachment of the epithelial cells to the tooth surface was mediated by hemidesmosomes (HDs) as in vivo. Laminin-5 (Ln-5) was present in the extracellular matrix (ECM) between the tooth and the epithelium as well as in the BM structure between the epithelium and the fibroblast-collagen matrix. Instead, Ln-10/11 was present only at the mesenchymal tissue side as is known to be the case in vivo. CONCLUSIONS The organotypic model presented expresses the characteristic structural and molecular features of the dento-epithelial junction and may be applied for studying physiological and pathological processes in the epithelial attachment.
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Affiliation(s)
- Jaana Oksanen
- Department of Periodontology, Institute of Dentistry, University of Turku, Finland.
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Hormia M, Owaribe K, Virtanen I. The dento-epithelial junction: cell adhesion by type I hemidesmosomes in the absence of a true basal lamina. J Periodontol 2001; 72:788-97. [PMID: 11453242 DOI: 10.1902/jop.2001.72.6.788] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND The junctional epithelium (JE) is a unique structure that makes contact with both a non-renewable hard tooth surface and with a basement membrane (BM) facing the connective tissue. Ultrastructurally, this attachment occurs through hemidesmosomes (HD) and a basal lamina-like extracellular matrix which, on the tooth side, is termed the internal basal lamina. In this study we investigated the expression of basal cell markers in the tooth-facing (TF) cells of JE. METHODS Samples of healthy marginal gingiva were removed by careful dissection. The expression of laminin-5 was used to indicate TF cell preservation in double immunofluorescence labeling and confocal laser scanning microscopy. RESULTS The results show that integrin alpha6beta4 and laminin-5 colocalize unequivocally in the TF cells. The results also show the specific expression of the basal cytokeratin 14 and the alpha(v) integrin subunit in the TF cells. All 3 major hemidesmosomal components BP180, BP230, and HD1 antigen are likewise present. On the other hand, type IV collagen, laminin-1/10, type VII collagen, and the BM proteoglycan perlecan are all absent from the dento-epithelial junction. CONCLUSIONS The results indicate that the epithelium-tooth interface is a unique structure wherein epithelial cells adhere by means of bona fide hemidesmosomes to an epithelium-derived extracellular matrix lacking most of the common BM components. Moreover, TF cells differ from connective tissue facing (CTF) cells, not only by their cell surface molecules and their production of extracellular matrix, but also by their cytoskeletal architecture.
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Affiliation(s)
- M Hormia
- Institute of Dentistry, University of Turku, Finland.
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12
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Abstract
The tooth, the hardest organ in the body, is known to be formed through highly elaborate, unique processes of differentiation and development. Basement membranes play critical roles in fundamentally important biological processes such as growth and differentiation, and for better understanding of the mechanism of development and maintenance of the tooth, specializations of tooth basement membranes are reviewed in detail in relation to their roles. The basement membrane at such diverse locations in the tooth as the inner enamel epithelium, maturation-stage ameloblasts, and junctional epithelium at the dentogingival border are specialized in their own highly unique ways for anchoring, firm binding, or mediation in the transport of substances. Thus, the role of basement membranes in the developing and mature tooth is manifold and for these roles individual basement membranes are specialized in their own specific ways which are rare or not seen in nondental tissues, and these specializations are essential for successful development and maintenance of the tooth.
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Affiliation(s)
- T Sawada
- Department of Ultrastructural Science, Tokyo Dental College, Chiba City, Japan
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Abstract
BACKGROUND There is limited clinical evidence that pathologically migrated teeth may reposition themselves after conventional periodontal treatment. The current research was carried out to determine the frequency of spontaneous repositioning of pathologically migrated teeth after routine periodontal therapy, and to study the relation between the severity of migration and the degree of repositioning following treatment. METHODS Sixteen patients with moderate to severe periodontal disease and presenting 33 diastema sites secondary to pathologic migration participated in this study. After conventional periodontal treatment had been performed, reactive repositioning was assessed by measuring the space between pathologically migrated teeth and adjacent teeth on study models obtained at baseline, re-evaluation at 6 weeks after scaling and root planing, and 4 months after surgery. RESULTS After scaling and root planing only, 48.5% of all sites exhibited some degree of repositioning with 36.4% of all sites closing completely. After surgery (6 months after baseline observations), 69.7% of all sites exhibited some degree of repositioning with 51.5% of all sites closing completely. When only small to moderate diastemata were considered (<1 mm), 77.8% of sites closed completely. CONCLUSIONS The findings of this study support the hypothesis that spontaneous repositioning after conventional periodontal treatment is likely, particularly when only light to moderate degrees of pathologic migration are considered. We hypothesize that this spontaneous movement is due to wound contraction during healing.
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Affiliation(s)
- P E Gaumet
- University of Texas Health Science Center at San Antonio, Department of Periodontics, 78284-7894, USA
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Mullen LM, Richards DW, Quaranta V. Evidence that laminin-5 is a component of the tooth surface internal basal lamina, supporting epithelial cell adhesion. J Periodontal Res 1999; 34:16-24. [PMID: 10086882 DOI: 10.1111/j.1600-0765.1999.tb02217.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Laminin-5 (Ln-5) is an extracellular matrix (ECM) glycoprotein found in epithelial basal laminae. We studied its expression on the surface of rat molars, in relationship to the location of the internal basal lamina (IBL) of the junctional epithelium (JE). In order to avoid disruption of the JE-tooth interface as much as possible, the surface of molars was prepared by mechanical removal of tissue debris and detergent/osmotic lysis of epithelial cell layers, and directly stained by immunohistochemistry, without sectioning. Antibodies to Ln-5 specifically stained a narrow band in the region of the cemento-enamel junction (CEJ), consistent with the expected location of the IBL. Western blotting of ECM material detergent--solubilized from the prepared tooth surfaces confirmed the molecular nature of Ln-5 identified by immunohistochemistry. By the use of a high-definition 3-D microscope, it appeared that Ln-5 coated the most apical part of the enamel and the most coronal portion of the cementum, on either side of the CEJ. In adhesion assays performed directly on tooth surfaces, epithelial cells adhered preferentially to the Ln-5 coated area of the tooth compared to the root surface, which is coated by other ECM components. Adhesion to the Ln-5 coated surface was specifically inhibited by a function-blocking monoclonal antibody to Ln-5. These results suggest that Ln-5 is a component of the IBL, and that it may be important in promoting adhesion of JE cells onto the tooth surface.
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Affiliation(s)
- L M Mullen
- Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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Hormia M, Sahlberg C, Thesleff I, Airenne T. The epithelium-tooth interface--a basal lamina rich in laminin-5 and lacking other known laminin isoforms. J Dent Res 1998; 77:1479-85. [PMID: 9663432 DOI: 10.1177/00220345980770070201] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The attachment of the marginal gingiva to the tooth surface is mediated by a thin nonkeratinized epithelium termed the junctional epithelium (JE). Ultrastructural studies have revealed that the attachment of the JE to the tooth surface occurs through hemidesmosomes (HD) and a basal lamina-like extracellular matrix termed the internal basal lamina (IBL). We have previously shown that neither type IV collagen nor prototypic laminin, two common components of basement membranes (BM), is present in the IBL between the epithelium and the tooth. In the present study, we show that laminin-5 is a major component of the IBL in both rodent and human tissues. By using in situ hybridization, we also show that the cells of the JE express the LAMC2 gene of laminin-5. In other parts of gingival epithelium, LAMC2 gene expression is less prominent. Our results indicate that the epithelium-tooth interface is a unique structure wherein epithelial cells are induced to secrete a basal lamina containing laminin-5 and no other presently known laminin isoform.
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Affiliation(s)
- M Hormia
- Institute of Dentistry, University of Turku, Finland
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