Effect of Physical Vapor Deposition on Cutting Efficiency of Nickel-Titanium Files
Schäfer
Regulation of Tissue Inhibitors of Metalloproteinase-1 Gene Expression by Cytokines in Human Gingival Fibroblasts
Yang, Tsai, Lu, Huang and Chang
Effects of Parachlorophenol and Camphorated Parachlorophenol on the Phagocytic Activities of a Murine Macrophage Cell Line (RAW264.7)
Barid, Nawawi, and Sosroseno
In Vitro Cytotoxicity Evaluation of Endodontic Sealers Exposed to Heat Before Assay
Neff, Layman and Jeansonne
EM Evaluation of Bacterial Biofilm and Microorganisms on the Apical External Root Surface of Human Teeth
Leonardo, Rossi, Silva, Ito, and Bonifácio
Effect of Physical Vapor Deposition on Cutting Efficiency of Nickel-Titanium Files
Edgar Schäfer, Prof, Dr
The purpose of this study was to investigate possible changes in cutting efficiency of nickel-titanium K-files that had undergone physical vapor deposition coating. Titanium nitride coatings were deposited using different process parameters. A total of 84 nickel-titanium K-files (size 35) were randomly divided into 7 groups of 12 instruments each. Groups A to F (experimental): instruments were coated with titanium nitride using different process parameters regarding substrate temperature, applied voltage, coating thickness, and ion bombardment. Group K (control): samples were not coated with titanium nitride. The cutting efficiency of all instruments was determined in a rotary working motion by means of a computer-driven testing device. Special plastic samples with a cylindrical canal were used, and the maximum penetration depth of the instruments into the lumen was the criterion for cutting efficiency. Instruments of groups A, F, and C achieved significantly greater penetration depths than the uncoated instruments of the control group (p < 0.05). Cutting efficiency of physical vapor deposition-coated nickel-titanium files was increased by up to 26.2% in comparison with uncoated instruments.
Regulation of Tissue Inhibitors of Metalloproteinase-1 Gene Expression by Cytokines in Human Gingival Fibroblasts
Yu-Yen Yang, MS, Hui-Fang Tsai, MS, Shiou-Chin Lu, MS, Ya-Fang Huang, MS and Yu-Chao Chang, DDS, MMS
Tissue inhibitors of metalloproteinase (TIMP) are important participants in various physiological processes that involve tissues remodeling. They help maintain a delicate balance between physiological degradation and synthesis of the extracellular matrix. A better understanding of TIMP activity will be helpful in understanding the etiology of periapical lesions and their means of treatment. The fibroblast is a prominent cellular component of the periapical tissues. The potential implications of cytokine-mediated tissue destruction still remain to be elucideated. The purpose of this stidy was to determine the effects of interleukin (IL)-1α and transforming growth factor (TGF)-β on the expressing of TIMP-1 by primary gingival fibroblast cultures. After exposure to cytokines for 8 h, total RNA in gingival fibroblasts was isolated and evaluated by reverse-transcriptase polymerase chain reaction. Densitometric analysis of the TIMP-1 mRNA gene expression, after normalization by β-actin, demonstrated that exposure to IL-1α resulted in a decreased level of TIMP-1 mRNA compared with the control groups. However, the TIMP-1 mRNA was up-regulated by TGF-β. In addition, when the cells were cultured in combination with TGF-β (1ng/ml) and IL-1α for 8 h, the level of TIMP-1 mRNA was dramatically reduced. These results demonstrated that in human periapical tissue cytokines differentially and specifically regulate expression of TIMP-1 mRNA. An understanding of the actions of cytokines on gingival fibroblasts may result in new therapies to augment current treatment of periapical lesions.
Effects of Parachlorophenol and Camphorated Parachlorophenol on the Phagocytic Activities of a Murine Macrophage Cell Line (RAW264.7)
Izzata Barid, DDS, MS, Soetomo Nawawi, DDS, DPHdent and Wihaskoro Sosroseno, DDS, PhD
The aim of this study was to determine whether the phagocytic functions of a murine macrophage cell line (RAW264.7 cells) may be altered by parachlorophenol (PCP) and camphorated parachlorophenol (CMCP). The adherence of capacities of PCP- or CMCP-treated cells on plastic surfaces were much lower than those of untreated cells. When the PCP or CMCP-treated cells were incubated with Actinobacillus actinomycetemcomitans, phagocytosis of these cells was significantly reduced in a dose-dependent fashion compared with that of untreated cells. Preactivation with bacterial lipopolysaccharide on PCP- and CMCP-treated cells failed to completely restore the phagocytosis of this periodontopathogen. The phagocytic functions of PCP- or CMCP-treated cells to this periodontopathogen opsonized with anti-A. actinomycetemcomitans were also reduced compared with those of untreated cells but were comparable with those of untreated cells incubated with unopsonized bacteria. The results of this study indicated, therefore, that both PCP and CMCP may, indeed, reduce the phagocytic activities of murine macrophages.
In Vitro Cytotoxicity Evaluation of Endodontic Sealers Exposed to Heat Before Assay
Theodore Neff, DDS, MS, Don Layman, PhD and Billie Gail Jeansonne, DDS, PhD
During warm-vertical condensation of gutta-percha, endodontic sealers are exposed to temperatures that potentially alter their cytotoxicity profiles. This study investigated the effects of heat on sealer toxicity by using the CyQuant® assays for cell adhesion and proliferation of human gingival fibroblasts. Seven sealers were exposed to one of the following temperatures for 10 min before assay: 23oC, 43oC, or 100oC. Adhesion data were used to determine percentage of cells bound, and proliferation data were used to determine percentage of change in cell number from 24 to 72 h, for each sealer at each temperature. The temperatures of 23oC, 43oC, or 100oC were significantly different in both the adhesion and proliferation assays. Sealer type and temperature were significant variables in both assays. The changes in toxicity measured by adhesion and proliferation for each sealer were not always similar. Roth 801 and Roth 811, after exposure to 100oC, showed enhanced adhesion but not proliferation, whereas Kerr PCS and Dentalis, after exposure to 100oC, showed decreased adhesion but enhanced proliferation. AH Plus and AH26 showed an increase in adhesion and proliferation after heat exposure, whereas Sealapex remained virtually unaffected.
EM Evaluation of Bacterial Biofilm and Microorganisms on the Apical External Root Surface of Human Teeth
Mário R. Leonardo, DDS, PhD, Marcos A. Rossi, MD, PhD, Léa A. B. Silva, DDS, PhD, Izabel Y. Ito, PhD and Kleber C. Bonifácio, DDS, MSc
The aim of this study was to evaluate the presence of bacterial biofilm on the external surface of the root apex in teeth with pulp necrosis, with and without radiographically visible periapical lesions, and in teeth with a vital pulp. Twenty-one teeth were extracted, eight with pulp necrosis and periapical lesions, eight with pulp necrosis without radiographically visible periapical lesions, and five with a vital pulp. The roots were sectioned, and the root apexes (+ 3 mm) were processed for scanning electron microscope evaluation. The surface of the apical root was evaluated for the presence of microorganisms, root resorption, and biofilm. There were no microorganisms on the apical root surface of either teeth with pulp vitality or with pulp necrosis with no radiographically visible periapical lesions. Microorganisms were always present in teeth with pulp necrosis and radiographically visible periapical lesions. These included cocci, bacilli, and filaments and the presence of an apical biofilm. Apical biofilm is clinically important because microbial biofilms are inherently resistant to antimicrobial agents and cannot be removed by biomechanical preparation alone. This may cause failure of endodontic treatment as a consequence of persistent infection.