Tissue Barrier (tissue + barrier)

Distribution by Scientific Domains

Kinds of Tissue Barrier

  • hard tissue barrier


  • Selected Abstracts


    Comparison of acidic fibroblast growth factor on collagen carrier with calcium hydroxide as pulp capping agents in monkeys

    DENTAL TRAUMATOLOGY, Issue 5 2007
    Zhimei Li
    Abstract,,, Acidic fibroblast growth factor (aFGF) has been shown to facilitate wound healing by stimulating fibroblast proliferation and angiogenesis. It has also been reported to possess a powerful anti-apoptotic function This study compared the histological pulp responses to aFGF on collagen carrier and Ca(OH)2 placed on the mechanically exposed dental pulp in monkeys at two observation periods. Thirty-six teeth with pulp exposures were distributed into three groups according to the capping agents used prior to application of the coronal seal: collagen-based matrix carrier (group 1), aFGF on the collagen-based matrix carrier (group 2) and aqueous calcium hydroxide [Ca(OH)2] paste (group 3). Specimens were harvested at 6 and 13 weeks postoperatively and prepared for hematoxylin and eosin, and Gram staining. Histological qualitative evaluation of pulp responses were performed under the light microscope following criteria modified from Cox et al. (17) and Hu et al. (18). Semi-quantitative analysis was also carried out using Kruskal,Wallis and Mann,Whitney U -tests. There was neither negligible inflammatory infiltrates with no bacteria present in the three groups at both timings, nor was there any significant difference in the soft tissue organization among the three groups at or between the 6- and 13-week observation periods. At 6 weeks, the hard tissue barrier produced by Ca(OH)2 group (1.040 ± 0.089) was significantly more superior than aFGF/collagen carrier group (1.930 ± 0.825) (P = 0.030) as well as collagen carrier group (3.142 ± 1.069, P = 0.018). At 13 weeks, both aFGF/collagen carrier group (1.214 ± 0.485) and the collagen carrier group (1.457 ± 0.814) produced significantly better hard tissue barrier (P = 0.040 and P = 0.017, respectively) than earlier timing. However, these two groups did not induce significantly improved hard tissue barrier compared to that produced by aqueous Ca(OH)2 paste which stimulated matrix secretion in a polar tubular dentin-like pattern. [source]


    Apexogenesis after initial root canal treatment of an immature maxillary incisor , a case report

    INTERNATIONAL ENDODONTIC JOURNAL, Issue 1 2010
    S. R. Kvinnsland
    Abstract Aim, To present a case where a traumatized, immature tooth still showed capacity for continued root development and apexogenesis after root canal treatment was initiated based on an inaccurate pulpal diagnosis. Summary, Traumatic dental injuries may result in endodontic complications. Treatment strategies for traumatized, immature teeth should aim at preserving pulp vitality to ensure further root development and tooth maturation. A 9-year-old boy, who had suffered a concussion injury to the maxillary anterior teeth, was referred after endodontic treatment was initiated in tooth 21 one week earlier. The tooth had incomplete root length, thin dentinal walls and a wide open apex. The pulp chamber had been accessed, and the pulp canal instrumented to size 100. According to the referral, bleeding from the root made it difficult to fill the root canal with calcium hydroxide. No radiographic signs of apical breakdown were recorded. Based on radiographic and clinical findings, a conservative treatment approach was followed to allow continued root development. Follow-up with radiographic examination every 3rd month was performed for 15 months. Continued root formation with apical closure was recorded. In the cervical area, a hard tissue barrier developed, which was sealed with white mineral trioxide aggregate (MTA). Bonded composite was used to seal the access cavity. At the final 2 years follow-up, the tooth showed further root development and was free from symptoms. Key learning points, ,,Endodontic treatment of immature teeth may result in a poor long-term prognosis. ,,The pulp of immature teeth has a significant repair potential as long as infection is prevented. ,,Treatment strategies of traumatized, immature permanent teeth should aim at preserving pulp vitality to secure further root development and tooth maturation. ,,Radiographic interpretation of the periapical area of immature teeth may be confused by the un-mineralized radiolucent zone surrounding the dental papilla. [source]


    Complex endodontic treatment of an immature type III dens invaginatus.

    INTERNATIONAL ENDODONTIC JOURNAL, Issue 10 2008
    A case report
    Abstract Aim, To report the endodontic treatment of an immature maxillary central incisor with dens invaginatus. Summary, Dens invaginatus is a rare malformation of teeth, probably resulting from an infolding of the dental papilla during tooth development. The present case describes the complex endodontic treatment of a type III dens invaginatus in an immature maxillary central incisor with a necrotic pulp and abscess formation. The initial treatment goal was to achieve apexification of the pseudocanal root and conservative root canal treatment in the main canal. Following 1-year of treatment with calcium hydroxide dressings, radiography revealed a healing response, but no sign of a hard tissue barrier at the apex. Periapical surgery with the placement of a zinc oxide cement (IRM) root-end filling was considered successful at the 4-year follow-up. Key learning points ,,The complexity of the canal system and open apex in dens invaginatus present a challenge to endodontic treatment. ,,Correct diagnosis and treatment planning are fundamental to treatment of dens invaginatus. ,,Periapical surgery is indicated in cases of unsuccessful apexification in immature teeth with dens invaginatus and nonvital pulp. [source]


    The effect of mineral trioxide aggregate on the apexification and periapical healing of teeth with incomplete root formation

    INTERNATIONAL ENDODONTIC JOURNAL, Issue 1 2006
    W. T. Felippe
    Abstract Aim, To evaluate the influence of mineral trioxide aggregate (MTA) on apexification and periapical healing of teeth in dogs with incomplete root formation and previously contaminated canals and to verify the necessity of employing calcium hydroxide paste before using MTA. Methodology, Twenty premolars from two 6-month old dogs were used. After access to the root canals and complete removal of the pulp, the canal systems remained exposed to the oral environment for 2 weeks. Canal preparation was then carried out using Hedström files, under irrigation with 1% sodium hypochlorite, 1 mm short of the radiographic apex. After drying, the canals of two premolars in each dog were left empty (control group). The other eight teeth in each animal were divided into two experimental groups. The apical thirds of the canals of group 1 were filled with MTA. In the teeth of group 2, the canals were dressed with a calcium hydroxide,propylene glycol paste. After 1 week, the paste was removed and the apical third was filled with MTA. All teeth were restored with reinforced zinc oxide cement (IRM) and amalgam. The animals were killed 5 months later, and blocks of the teeth and surrounding tissues were submitted to histological processing. The sections were studied to evaluate seven parameters: formation of an apical calcified tissue barrier, level of barrier formation, inflammatory reaction, bone and root resorption, MTA extrusion, and microorganisms. Results of experimental groups were analysed by Wilcoxon's nonparametric tests and by the test of proportions. The critical value of statistical significance was 5%. Results, Significant differences (P < 0.05) were found in relation to the position of barrier formation and MTA extrusion. The barrier was formed in the interior of the canal in 69.2% of roots from MTA group only. In group 2, it was formed beyond the limits of the canal walls in 75% of the roots. MTA extrusion occurred mainly in roots from group 2. There was similarity between the groups for the other parameters. Conclusions, Mineral trioxide aggregate used after root canal preparation favoured the occurrence of the apexification and periapical healing. The initial use of calcium hydroxide paste was not necessary for apexification to occur, and has shown to be strongly related to the extrusion of MTA and formation of barriers beyond the limits of the root canal walls. [source]


    The effect of the renewal of calcium hydroxide paste on the apexification and periapical healing of teeth with incomplete root formation

    INTERNATIONAL ENDODONTIC JOURNAL, Issue 7 2005
    M. C. S. Felippe
    Abstract Aim, To evaluate the influence of renewing calcium hydroxide paste on apexification and periapical healing of teeth in dogs with incomplete root formation and previously contaminated canals. Methodology, Forty premolars from four 6-month-old dogs were used. After access to the root canals and complete removal of the pulp, the canal systems remained exposed to the oral environment for 2 weeks. Canal preparation was then carried out using Hedströem files, under irrigation with 1% sodium hypochlorite, 1 mm short of the radiographic apex. After drying, the canals of one premolar in each dog were left empty (group 4-control), and those of the other nine teeth in each animal were filled with a calcium hydroxide-propylene glycol paste. All teeth were restored with reinforced zinc oxide cement (IRM) or IRM and amalgam (group 4). The paste was renewed and the teeth restored again 1 week later. Then, the nine teeth in each animal were divided into three experimental groups: group 1 , paste not changed; group 2 , paste renewed every 4 weeks for 5 months; and group 3 , paste renewed after 3 months had elapsed. The teeth were restored with IRM and amalgam (groups 1 and 3) or IRM (group 2). The animals were killed 5 months later, and blocks of the teeth and surrounding tissues were submitted to histological processing. The sections were studied to evaluate six parameters: apical calcified tissue barrier, inflammatory reaction, bone and root resorption, paste extrusion and microorganisms. Results of experimental groups were analysed by Kruskal,Wallis nonparametric tests and by the test of proportions. The critical value of statistical significance was 5%. Results, Significant differences (P < 0.05) were found in relation to the presence of bone resorption and paste in the periradicular area, the formation of a calcified tissue barrier at the apex, and the intensity of the apical inflammatory reaction. Bone resorption was more evident in group 1 (medicament not changed), and the presence of paste in the periodontal tissues was more common in groups 2 and 3. Renewal of the paste reduced the intensity of the inflammatory reaction (groups 2 and 3), but the formation of apical calcified tissue was more noticeable in the teeth where the paste had not been renewed. Conclusions, Replacement of calcium hydroxide paste was not necessary for apexification to occur, however, it did reduce significantly the intensity of the inflammatory process. Monthly renewal of calcium hydroxide paste reduced significantly the occurrence of apexification. [source]


    Scanning electron microscopy evaluation of the hard tissue barrier after pulp capping with calcium hydroxide, mineral trioxide aggregate (MTA) or ProRoot MTA

    AUSTRALIAN ENDODONTIC JOURNAL, Issue 2 2009
    Eduardo Galia Reston dds
    Abstract The aim of this study was to investigate the morphology and localisation of calcium hydroxide- and mineral trioxide aggregate (MTA)-induced hard tissue barriers after pulpotomy in dogs' teeth. Pulpotomies were performed on maxillary and mandibular premolars of five dogs. The teeth were assigned into three groups according to the pulp-capping agent used. The pulpal wounds were capped with calcium hydroxide (Ca(OH)2, control), MTA or ProRoot MTA, and the cavities were restored with amalgam. After a 90-day follow-up period, the dogs were euthanised and the teeth were examined under scanning electron microscopy (SEM). An image-processing and analysis software was used to delimit the perimeters of the root canal area and the hard tissue barrier to determine the percentage of root canal obliteration. SEM data were used to assess the morphology, localisation and extension of the reparative hard tissue barriers. ProRoot MTA was statistically different from MTA and Ca(OH)2 (P < 0.05) regarding tissue barrier morphology. Localisation data showed that ProRoot MTA was significantly different from Ca(OH)2 (P < 0.05) and similar to MTA (P > 0.01; P > 0.05). No statistically significant difference (P > 0.01; P > 0.05) was observed between MTA and Ca(OH)2. A larger number of complete (centroperipheral) hard tissue barriers with predominance of dentinal tubules was observed to the ProRoot MTA when compared with the Ca(OH)2 group. [source]


    Organization of the connective tissue barrier around long-term loaded implant abutments in man

    CLINICAL ORAL IMPLANTS RESEARCH, Issue 5 2002
    Gianmario Schierano
    Abstract: The study aimed to investigate the connective tissue seal and the spatial organization of collagen fibers around long-term loaded implants in man. Block specimens containing smooth titanium implant abutments and the surrounding supracrestal connective tissue were obtained from patients rehabilitated for at least 1 year with implant-retained overdentures or implant-supported fixed prostheses and were histologically investigated. The histological features of the connective tissue around long-term loaded titanium abutments were specific: the tissue was rich in collagen fibers, organized in bundles, presenting a constant spatial arrangement, similar to that reported in animal studies. Circular fibers, the most numerous, were located externally, and longitudinal fibers internally. Radial fibers inserted on the abutment surface, similar to those of the periodontal system, were not observed in any case. No histological differences were found between tissue sampled around implants supporting a fixed restoration and those anchoring an overdenture. [source]


    Importance of P-glycoprotein for drug disposition in humans

    EUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 2003
    M. F. Fromm
    The ATP-binding cassette transporter P-glycoprotein is now recognized as an important determinant for disposition of multiple drugs. The use of P-glycoprotein-expressing cell lines, the generation of P-glycoprotein knockout mice as well as studies in animals and humans contributed to a better understanding on the role of active transport processes for drug disposition. P-glycoprotein is located in tissues with excretory function such as intestine, liver and kidney. Moreover, due to its expression in important blood,tissue barriers (blood,brain and blood,testis barriers), in lymphocytes and in placenta it limits tissue penetration of its substrates. Induction and inhibition of P-glycoprotein have now been identified as important underlying mechanisms of drug interactions in humans. Using selected examples, this review summarizes currently available data on the impact of P-glycoprotein for bioavailability of drugs, drug interactions and drug effects. [source]


    Scanning electron microscopy evaluation of the hard tissue barrier after pulp capping with calcium hydroxide, mineral trioxide aggregate (MTA) or ProRoot MTA

    AUSTRALIAN ENDODONTIC JOURNAL, Issue 2 2009
    Eduardo Galia Reston dds
    Abstract The aim of this study was to investigate the morphology and localisation of calcium hydroxide- and mineral trioxide aggregate (MTA)-induced hard tissue barriers after pulpotomy in dogs' teeth. Pulpotomies were performed on maxillary and mandibular premolars of five dogs. The teeth were assigned into three groups according to the pulp-capping agent used. The pulpal wounds were capped with calcium hydroxide (Ca(OH)2, control), MTA or ProRoot MTA, and the cavities were restored with amalgam. After a 90-day follow-up period, the dogs were euthanised and the teeth were examined under scanning electron microscopy (SEM). An image-processing and analysis software was used to delimit the perimeters of the root canal area and the hard tissue barrier to determine the percentage of root canal obliteration. SEM data were used to assess the morphology, localisation and extension of the reparative hard tissue barriers. ProRoot MTA was statistically different from MTA and Ca(OH)2 (P < 0.05) regarding tissue barrier morphology. Localisation data showed that ProRoot MTA was significantly different from Ca(OH)2 (P < 0.05) and similar to MTA (P > 0.01; P > 0.05). No statistically significant difference (P > 0.01; P > 0.05) was observed between MTA and Ca(OH)2. A larger number of complete (centroperipheral) hard tissue barriers with predominance of dentinal tubules was observed to the ProRoot MTA when compared with the Ca(OH)2 group. [source]


    Danofloxacin-mesylate is a substrate for ATP-dependent efflux transporters

    BRITISH JOURNAL OF PHARMACOLOGY, Issue 4 2007
    J A Schrickx
    Background and purpose: Next to its broad antimicrobial spectrum, the therapeutic advantages of the fluoroquinolone antimicrobial drug Danofloxacin-Mesylate (DM) are attributed to its rapid distribution to the major target tissues such as lungs, intestines and the mammary gland in animals. Previous analyses revealed that effective drug concentrations are achieved also in luminal compartments of these organs, suggesting that active transport proteins facilitate excretion into the luminal space. Members of the ATP-Binding Cassette (ABC) superfamily, including P-gp, BCRP and MRP2 are known to be expressed in many tissue barriers and in cell-membranes facing luminal compartments. Hence we hypothesized that DM is a substrate for one of these efflux-transporters. Experimental approach: Confluent monolayers of Caco-2 cells, grown on microporous membranes in two-chamber devices were used. DM concentrations were measured by fluorimetric assay after HPLC of the culture media. Key results: DM transport across Caco-2 cells was asymmetric, with a rate of secretion exceeding that of absorption. The P-gp inhibitors PSC833 and GF120918 and the MRP-inhibitor MK571 partially decreased the secretion of DM and increased its absorption rate. The BCRP inhibitor, Ko143, decreased secretion only at a concentration of 1 ,M. When DM was applied together with ciprofloxacin, secretion as well as absorption of DM decreased. Conclusions and Implications: DM is a substrate for the efflux transporters P-gp and MRP2, whereas the specific role of BCRP in DM transport needs further evaluation. These findings provide a mechanistic basis for the understanding of the pharmacokinetics of DM in healthy and diseased individuals. British Journal of Pharmacology (2007) 150, 463,469. doi:10.1038/sj.bjp.0706974 [source]