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At least 91 records · Page 5Linked to original sources
PubMed2005

Marker of cemento-periodontal ligament junction associated with periodontal regeneration.

OBJECTIVE: The purpose of this study was to identify factors promoting formation of the cemento-periodontal ligament junction. BACKGROUND: Regeneration of the cemento-periodontal ligament junction is an important factor in recovery of the connective tissue attachment to the cementum and it is important to identify all specific substances that promote its formation. To clarify the substances involved in cemento-periodontal ligament junction formation, we produced a monoclonal antibody (mAb) to human cemento-periodontal ligament junction (designated as the anti-TAP mAb) and examined its immunostaining properties and reactive antigen. METHODS: Hybridomas producing monoclonal antibody against human cemento-periodontal ligament junction antigens were established by fusing P3U1 mouse myeloma cells with spleen cells from BALB/c mice immunized with homogenized human cemento-periodontal ligament junction. The mAb, the anti-TAP mAb for cemento-periodontal ligament junction, was then isolated. The immunoglobulin class and light chain of the mAb were examined using an isotyping kit. Before immunostaining, antigen determination using an enzymatic method or heating was conducted. Human teeth, hard tissue-forming lesions, and animal tissues were immunostained by the anti-TAP mAb. RESULTS: The anti-TAP mAb was positive in human cemento-periodontal ligament junction and predentin but negative in all other human and animal tissues examined. In the cemento-osseous lesions, the anti-TAP mAb was positive in the peripheral area of the cementum and cementum-like hard tissues and not in the bone and bone-like tissues. The anti-TAP mAb showed IgM (kappa) and recognized phosphoprotein. CONCLUSION: The anti-TAP mAb is potentially useful for developing new agents promoting cementogenesis and periodontal regeneration.

Animals↗
PubMed2000

Cementum attachment protein enriches putative cementoblastic populations on root surfaces in vitro.

We tested the capacity of cementum attachment protein (CAP) to recruit putative cementoblastic populations to root surfaces in vitro by determining the phenotypic expression of periodontal ligament cloned cell populations. The clones were derived from cells that attached to either CAP-coated (experimental) or uncoated (control) root slices. Root slices were co-cultured with primary human periodontal ligament cells. Cloned and parent populations were analyzed for their capacity to express alkaline phosphatase (AP), osteopontin, bone sialoprotein (BSP), and CAP and to form mineralized tissue in vitro. The percentage of CAP- and BSP-positive clones was significantly higher in the experimental clones than in the controls. The percentage of cells positive for AP, BSP, and CAP was higher in the experimental clones than in their control counterparts. Mineralized tissue formation was observed only in the cell populations derived from the CAP-coated root slices. These results indicate that CAP is capable of recruiting putative cementoblastic populations on root slices in vitro and therefore might play an important role in cementogenesis during periodontal homeostasis and wound healing.

Alkaline Phosphatase↗
PubMed2002

Cementum: a phosphate-sensitive tissue.

Ectopic calcification within joints has been reported in humans and rodents exhibiting mutations in genes that regulate the level of extracellular pyrophosphate, e.g., ank and PC-1; however, periodontal effects of these mutations have not previously been examined. These initial studies using ank and PC-1 mutant mice were done to see if such mineral deposition and resulting ankylosis were occurring in the periodontium as well. Surprisingly, results indicated the absence of ankylosis; however, a marked increase in cementum formation on the root surfaces of fully developed teeth of these mutant mice was noted. Examination of ank mutant mice at earlier ages of tooth root formation indicated that this striking observation is apparent from the onset of cementogenesis. These findings suggest that cells within the periodontal region are highly responsive to changes in phosphate metabolism. This information may prove valuable in attempts to design successful therapies for regenerating periodontal tissues.

Animals↗
PubMed2004

Mouse cellular cementum is highly dependent on growth hormone status.

Cementum is known to be growth-hormone (GH)-responsive, but to what extent is unclear. This study examines the effects of extremes of GH status on cementogenesis in three lines of genetically modified mice; GH excess (giant), GH antagonist excess (dwarf), and GH receptor-deleted (GHR-KO) (dwarf). Age-matched mandibular molar tissues were processed for light microscope histology. Digital images of sections of first molar teeth were captured for morphometric analysis of lingual root cementum. Cross-sectional area of the cellular cementum was a sensitive guide to GH status, being reduced nearly 10-fold in GHR-KO mice, three-fold in GH antagonist mice, and increased almost two-fold in giant mice (p < 0.001). Cellular cementum length was similarly influenced by GH status, but to a lesser extent. Acellular cementum was generally unaffected. This study reveals cellular cementum to be a highly responsive GH target tissue, which may have therapeutic applications in assisting regeneration of the periodontium.

Animals↗
PubMed1975

Histological study on the postnatal development and sequence of eruption of the maxillary cheek-teeth of rabbits (Oryctolagus cuniculus).

The development and sequence of eruption of the maxillary cheek-teeth of rabbits were studied by histological methods. The presence of three deciduous molars which were replaced by correspondent premolars and of three permanent molars without predecessors was confirmed. The eruption of the maxillary deciduous molars was shown to begin at 4 days postnatally and that of the permanent molar at 9 days, while the eruption of the premolars occurs from 24 days on, replacing the deciduous molars which are exfoliated. The last tooth to erupt is the M3. At 32 days all the permanent cheek-teeth are erupted. The deciduous molars are completely developed at birth, root resorption starting at 4 days. On the first day the premolars are in the bell stage and in the M1 and M2 amelogenesis is taking place. After 27 days the development of the permanent maxillary cheek-teeth is completed. Dentinogenesis, amelogenesis and cementogenesis were observed in all of them.

Age Factors↗
PubMed1993

Development of the murine periodontium. I. Role of basement membrane in formation of a mineralized tissue on the developing root dentin surface.

The presence of basement membrane components on the forming root surface suggests a role for this structure during cementoblast differentiation. The purpose of this study was to investigate the role of root-associated basement membrane (RBM) in murine cementogenesis using tissue separation and recombination techniques. Root dentin specimens, with or without RBM, were combined with dental sac tissue, cultured for 2 weeks, harvested, and examined by light, immunofluorescence, and electron microscopy. Recombinations in which RBM was preserved on the root dentin surface were characterized by formation of an adherent mineralized tissue resembling acellular cementum; recombinations in which RBM was excluded were characterized by formation of mineralized tissue which did not adhere to the root dentin surface. These results suggest that formation of an adherent mineralized tissue on the developing root dentin surface is dependent upon the presence of indigenous basement membrane components.

Animals↗
PubMed1993

Development of the murine periodontium. II. Role of the epithelial root sheath in formation of the periodontal attachment.

Experimental manipulation of the developing murine tooth germ has provided evidence that basement membrane components on the forming root surface are involved in early periodontal attachment formation. The purpose of this investigation was to determine the role of epithelial root sheath (ERS) cells in murine cementogenesis and periodontal ligament formation using tissue separation and recombination techniques. Root dentin specimens, with and without root-associated basement membrane components (D + RBM or D - RBM), were recombined with dental sac in the presence or absence of ERS. Recombinations were cultured for 2 weeks, harvested, and examined by light, electron, and immunofluorescence microscopy. Mineralized tissue formed in all tissue recombinations. However, when ERS was included in recombinations between D + RBM and dental sac, 25% of recombinations formed a periodontal ligament with fibrous attachment of the root specimen to adjacent bone. These results support the hypothesis that root and periodontal ligament formation is influenced by epithelio-mesenchymal interactions and further support a key role for ERS in these processes.

Alveolar Process↗
PubMed1998

The effect of root surface demineralization on bone morphogenetic protein-2-induced healing of rat periodontal fenestration defects.

The purpose of this study was to investigate the effect of acid conditioning of root surfaces during recombinant human bone morphogenetic protein-2 (rhBMP-2) induced periodontal regeneration in vivo. The buccal aspect of molar roots were denuded of their periodontal ligament through a bony window created in the mandible of 34 Wistar rats under general anesthesia. Three groups of 11 or 12 animals received either 10 microL of 50 g/mL rhBMP-2 in a collagen gel over the surgical defect (BMP) or 10 microL of collagen gel only (COL) or were left untreated (UN). Each of the 3 groups were further subdivided into those that received prior root acid conditioning with 35% phosphoric acid gel and those without acid conditioning. Animals were sacrificed 10 days after surgery and the tissues processed for histological examination. The BMP groups with and without acid conditioning developed significantly more bone over the second molar (3.89+/-0.86% and 7.62+/-0.93%, respectively; mean+/-SE), compared with the respective COL (1.24+/-0.26% and 2.77+/-0.52%) and UN groups (1.34+/-0.35% and 3.69+/-0.37%) (P <0.05). Furthermore, significantly more bone was found in the BMP non-acid conditioned group compared with all other groups (P <0.05). Acid conditioning promoted significantly more ankylosis (50%) compared with non-acid conditioning (6.3%) (P=0.007). New cementum formation was greatest in the BMP acid conditioned group (628.4+/-253.8 microm2) and lowest in the non-acid conditioned UN group (207.6+/-36.4 microm2) (P <0.05). This is the first known report evaluating the effects of root acid conditioning after a single application of rhBMP-2 in vivo. Results suggest that root conditioning agents operating at low pH administered into the periodontal wound impairs early BMP-induced osteogenesis while simultaneously promoting BMP-induced cementogenesis.

Analysis of Variance↗
PubMed2000

Employing a transgenic animal model to obtain cementoblasts in vitro.

BACKGROUND: Proper formation of cementum, a mineralized tissue lining the tooth root surface, is required for development of a functional periodontal ligament. Further, the presence of healthy cementum is considered to be an important criterion for predictable restoration of periodontal tissues lost as a consequence of disease. Despite the significance of cementum to general oral health, the mechanisms controlling development and regeneration of this tissue are not well understood and research has been hampered by the lack of adequate in vitro experimental models. METHODS: In an effort to establish cementoblast cell populations, without the trappings of a heterogeneous population containing periodontal ligament (PDL) cells, cells were obtained from the root surface of first mandibular molars of OC-TAg transgenic mice. These mice contain the SV40 large T-antigen (TAg) under control of the osteocalcin (OC) promoter. Therefore, only cells that express OC also express TAg and are immortalized in vitro. Based on results of prior in situ studies, OC is expressed by cementoblasts during root development, but not by cells within the PDL. Consequently, when populations are isolated from developing molars using collagenase/trypsin digestion, only cementoblasts, not PDL cells, are immortalized and thus, will survive in culture. RESULTS: The resulting immortalized cementoblast population (OC/CM) expressed bone sialoprotein (BSP), osteopontin (OPN), and OC, markers selective to cells lining the root surface. These cells also expressed type I and XII collagen and type I PTH/PTHrP receptor (PTH1R). In addition to expression of genes associated with cementoblasts, OC/CM cells promoted mineral nodule formation and exhibited a PTHrP mediated cAMP response. CONCLUSIONS: This approach for establishing cementoblasts in vitro provides a model to study cementogenesis as required to enhance our knowledge of the mechanisms controlling development, maintenance, and regeneration of periodontal tissues.

Animals↗
PubMed2002

Factors that modulate the effects of bone morphogenetic protein-induced periodontal regeneration: a critical review.

The healing process initiated by a single molecular species of bone morphogenetic protein (BMP) such as BMP-2 or BMP-7 sets in motion a cascade of cellular events resulting in differentiation of progenitor cells into phenotypes involved in periodontal regeneration. For example, animal studies show that a single dose of recombinant human (rh) BMP-2 increases the rate of normal intramembranous bone formation and enhanced cementum formation during periodontal wound healing. However, the optimal effects of BMPs are modulated by a range of factors that need careful evaluation in clinical studies. These factors include the influence of root conditioning, occlusal loading, BMP dose, and the release characteristics of the carrier as well as the suitability of the model to evaluate the efficacy of BMPs. Each of these factors may affect the rate of BMP-induced osteogenesis and cementogenesis and subsequent periodontal ligament (PDL) formation during the early and late stages of periodontal wound healing. Although BMP-2 initiates stem cells along an osteogenic pathway, the dose may have to be of sufficient concentration to ensure other growth and differentiation factors do not redirect or retard the osteogenic potential of the cell. Understanding when to manipulate the cell's differentiation pathway with the application of single or multiple doses of BMPs at the appropriate concentration is required to optimize the effect of BMPs in periodontal wound healing. Therefore, different release profiles from the same carrier may be particularly important in tissues with mixed cell populations such as in the periodontium, where similar tissues like bone and cementum grow at different rates. Furthermore, treatment of intrabony defects with BMPs are likely to not only require appropriate temporal release of the BMP(s), but also a carrier that can serve as a template for new tissue formation providing space maintenance and supporting the mucoperiosteal flap. Many of these issues have not been adequately addressed from a periodontal standpoint; therefore the purpose of this review is to clarify our current understanding of the factors that are likely to modulate the effects of BMP-induced periodontal regeneration. Moreover, assessing the importance of these factors is essential prior to conducting expensive human clinical trials.

Acid Etching, Dental↗
PubMed2003

Gene therapy of bone morphogenetic protein for periodontal tissue engineering.

BACKGROUND: The reconstruction of lost periodontal support including bone, ligament, and cementum is a major goal of therapy. Bone morphogenetic proteins (BMPs) have shown much potential in the regeneration of the periodontium. Limitations of BMP administration to periodontal lesions include need for high-dose bolus delivery, BMP transient biological activity, and low bioavailability of factors at the wound site. Gene transfer offers promise as an alternative treatment strategy to deliver BMPs to periodontal tissues. METHODS: This study utilized ex vivo BMP-7 gene transfer to stimulate tissue engineering of alveolar bone wounds. Syngeneic dermal fibroblasts (SDFs) were transduced ex vivo with adenoviruses encoding either green fluorescent protein (Ad-GFP or control virus), BMP-7 (Ad-BMP-7), or an antagonist of BMP bioactivity, noggin (Ad-noggin). Transduced cells were seeded onto gelatin carriers and then transplanted to large mandibular alveolar bone defects in a rat wound repair model. RESULTS: Ad-noggin treatment tended to inhibit osteogenesis as compared to the control-treated and Ad-BMP-7-treated specimens. The osseous lesions treated by Ad-BMP-7 gene delivery demonstrated rapid chrondrogenesis, with subsequent osteogenesis, cementogenesis and predictable bridging of the periodontal bone defects. CONCLUSION: These results demonstrate the first successful evidence of periodontal tissue engineering using ex vivo gene transfer of BMPs and offers a new approach for repairing periodontal defects.

Adenoviridae↗
PubMed2006

Bone sialoprotein gene transfer to periodontal ligament cells may not be sufficient to promote mineralization in vitro or in vivo.

BACKGROUND: To improve regenerative therapies, it is important to understand the cells and factors modulating periodontal tissues. Our group has focused on bone sialoprotein (BSP), a mineralized tissue-selective protein considered to be involved in the initiation of cementogenesis and osteogenesis. In this study, we examined whether gene transfer of BSP into periodontal ligament (PDL) cells would result in an increased ability of PDL cells to promote mineralization in vitro and in vivo. METHODS: PDL cells obtained from CD-1 mice were immortalized using simian virus (SV) 40 large T antigen (TAg) and designated SV-PDL cells. SV-PDL cells were infected in vitro with LacZ gene-expressing control adenovirus vector. A 1,000 plaque-forming unit (pfu) titer was selected (based on X-gal staining) and cells were infected with mouse BSP-expressing replication-deficient adenoviral vector to determine the mRNA expression and protein level of BSP. Total RNA was isolated from cells on days 2, 4, and 6. Media were obtained on days 3, 5, and 7 for protein determination. Northern blot analysis was performed for mRNA expression and Western blot analysis for protein expression. To test the effect of BSP gene transfer on the mineralization of PDL cells, in vitro (von Kossa) and in vivo (severe combined immunodeficiency [SCID] mice) experiments were performed. RESULTS: Under normal conditions, PDL cells do not express BSP transcripts and do not promote significant mineralization. SV-PDL cells infected with a BSP viral vector expressed and secreted substantial levels of BSP as confirmed by Northern and Western blot analysis. BSP mRNA and protein levels were strong on day 2 and still apparent on day 6, although not as great. However, no mineral nodule formation was noted either in vitro or in vivo. CONCLUSIONS: Although BSP is an important and necessary protein for mineralization, it may not be sufficient for promoting mineralization without the addition or removal of other factors. Further studies will help to clarify the specific factors required for promoting mineralization, a required step for designing predictable periodontal regenerative therapies.

3T3 Cells↗
PubMed2000

[Cementum formation in rat molar roots].

Cementum is the calcified tissue covering roots of teeth and serves as attachment sites of the periodontal ligament. Although recent studies have suggested that extracellular matrix of cementum is very similar to that of bone, cementogenesis on a biological basis is still poorly understood. There are variations in the distribution and mineral contents of cementum depending on animal age, tooth species and position within the tooth roots. This paper reviews the formation and age-related changes of cellular and acellular cementum in rat molar roots, and discusses the effect of mechanical stress to the cementum formation.

Animals↗
PubMedDate not supplied

Evaluation of decalcified allogenic bone matrix grafts in and around root apices. A histological study.

Decalcified Allogenic Bone grafts were implanted in and around eighteen root apices after apicoectomy. The procedure was carried out on eighteen rabbits, dividing them into three groups of six rabbits each. The animals were sacrificed after 48-72 hours, 8-10 days & 8-10 weeks period of interval. Result of the present investigation reveal that DABM grafts stimulate osteogenesis and cementogenesis after the initial phase of inflammation. Tissues simulating bone and cementum appear at the apical end, speculating that the grafts would certainly result in physiological sealing of root apices. The possibility of saving the life of non vital teeth with or without wide apical foramen will enhance in future.

Animals↗
PubMed1996

Recombination of epithelial root sheath and dental papilla cells in vitro.

Hertwig's epithelial root sheath (HERS) cells were isolated and recombined with ectomesenchymal cells in vitro utilizing extracellular matrix components as substrate. After 14 days in culture, HERS cells were differentiated and exhibited a stratified organization. These features resembled those observed in vivo as epithelial rests of Malassez. A mineralization process was also present in HERS cells, in which calcium salts were deposited. This mineralization was correlated with the strong immunoexpression of osteopontin by HERS. The results obtained add support to the possible role of HERS in the secretion of hypocalcified material on the root during early cementogenesis.

Animals↗
PubMed1998

The biologic concept for the use of enamel matrix protein: true periodontal regeneration.

Guided tissue regeneration procedures have been used successfully to reestablish periodontal attachment. However, this new attachment reportedly differs from the original attachment in strength and continuity. Enamel matrix proteins secreted by Hertwig's epithelial sheath play an important role in cementogenesis on roots and in the development of the periodontal attachment apparatus. Enamel matrix protein harvested from developing porcine teeth, or enamel matrix derivative (Emdogain), is reported to induce true periodontal regeneration (the attachment of new, acellular cementum to the underlying dentin surface). The results of experimental and clinical trials of Emdogain are reviewed, and the procedure for application of the material is described.

Alveolar Bone Loss↗
PubMed1986

Cementum annulation and age determination in Homo sapiens. II. Estimates and accuracy.

The cementum annulation aging technique was evaluated in a sample of 80 clinically extracted premolars (age range 11-70 years). Demineralized thin sections (7 micron) stained with hematoxylin were used. The correlation (r) between age and adjusted count (number of annulations added to age of tooth eruption) was 0.78 for the entire sample (N = 73) and 0.86 for a subsample in which teeth with periodontal disease were excluded (N = 55). Standard error of the estimates ranged from 4.7 to 9.7 years depending on sex and health status of the tooth. The technique provided significantly better estimates for females than for males. The overall inaccuracy (mean absolute error) of the technique was 6.0 years, with a bias (mean error) of 0.26 years. Reduced major axis regression of adjusted count on age produced a slope of 0.797 for the entire sample and 0.889 for the nonperiodontal disease subsample. These slopes are consistent with a hypothesis of annual deposition of cementum rings given a decrease in cementogenesis with increasing age.

Adult↗
PubMed1989

Radioautographic study of [3H]mannose utilization during cementoblast differentiation, formation of acellular cementum, and development of periodontal ligament principal fibers.

The formation of acellular cementum and the deposition of [3H]mannose-labeled extracellular matrix were studied in 14-day-old Sprague-Dawley rats. The sequential events of cementogenesis and periodontal ligament formation observed by light and electron microscopy were described from the stage of an intact root sheath to postcementogenesis. Ultrastructural examination of cementoblasts and periodontal ligament fibroblasts revealed [3H]mannose labeling of the Golgi apparatus at 10 minutes, collagen secretion granules at 30 minutes, and the extracellular matrix beginning at 30 minutes. The extracellular matrix between cementoblasts and dentin was heavily labeled at 1 and 4 hours. Newly formed principal fibers of the periodontal ligament were also heavily labeled at 4 hours. Fully differentiated cementoblasts exhibited the largest sectional profiles and the highest number of silver grains per unit area of cytoplasm. The morphologic and radioautographic data suggest that during the formation of acellular cementum, the cementoblast phenotype is expressed for a short period of time, after which cementoblasts appear to mix with the fibroblasts of the periodontal ligament.

Animals↗