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Query: KEGG:D01931 (TiO2)
 11,320 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A blind, two-way crossover clinical trial was carried out to compare the effectiveness of plaque removal between a new, light energy conversion toothbrush incorporated with a semiconductor of TiO2 (test) and a similar toothbrush without the semiconductor (control). The study was completed by 73 school children aged 13-15 years. Each toothbrush was used for a period of 3 weeks. The mean differences between baseline plaque scores and after subjects used the test and control brushes were analyzed by the paired t-test. The Soladey 2 toothbrush showed significantly more reduction of plaque on the buccal surfaces of all teeth than the control brush. There was no significant difference in the plaque removing ability of the two brushes on the lingual aspects of the mandible and on the lingual surfaces of the maxillary posterior sextant. As the buccal surfaces are more likely to allow light to reach the semiconductor during brushing than the lingual areas, it is possible that the reported photocatalytic property of the semiconductor may be involved in some way in the observed reduction of plaque.
J Clin Periodontol 1992 Jul
PMID:Clinical evaluation of a light energy conversion toothbrush. 163 32

Quartz deposition in the rat lung causes an intense and persistent neutrophil alveolitis leading to parenchymal fibrosis. Bronchoalveolar leucocytes (BAL) from quartz-exposed rat lungs were studied for their effects on splenic lymphocyte proliferation; titanium dioxide (TiO2) was used as a control, non-fibrogenic dust. Seven days after the intratracheal instillation of 1 mg of quartz or TiO2 suspended in phosphate-buffered saline (PBS), BAL were recovered by lavage; the effect of PBS alone was also studied. TiO2-elicited BAL (macrophages greater than 98%) inhibited splenocytes responding to suboptimal phytohaemagglutinin (PHA) more than PBS-elicited BAL (macrophages greater than 98%); the effect was dependent on the BAL:splenic lymphocyte ratio. Quartz-elicited whole BAL (macrophages 49%, neutrophils 51%), and an alveolar macrophage-enriched population with purity of 87% separated from it, were less inhibitory to splenocyte mitogenesis than PBS-elicited BAL. A neutrophil-enriched population, with a purity of 80%, markedly enhanced splenocyte response to PHA. In addition, whole quartz BAL and the macrophage-enriched population obtained from it enhanced the mitogenesis of T cell-enriched lymphocytes at a much lower BAL:lymphocyte ratio. The neutrophil-enriched quartz BAL enhanced mitogenesis substantially more than the whole or macrophage-enriched population from quartz-exposed lung. Supernatants from normal macrophages, PBS BAL, TiO2 BAL, quartz BAL and both alveolar macrophage and neutrophil-enriched quartz populations were assessed for interleukin-1 (IL-1) activity. Quartz-BAL, quartz macrophages and quartz neutrophils all produced significantly higher IL-1 levels than PBS BAL; the supernatants from quartz neutrophils, however, showed the highest IL-1 activity. These findings suggest that quartz-elicited bronchoalveolar leukocytes, especially neutrophils, enhance lymphocyte proliferation and that increased IL-1 secretion by these cells is likely to be the effector molecule involved. These findings have important implications for immune response in mineral dust-stimulated lung and for inflammatory lung disease in general.
Clin Exp Immunol 1990 May
PMID:Immunomodulation in mineral dust-exposed lungs: stimulatory effect and interleukin-1 release by neutrophils from quartz-elicited alveolitis. 216 47

Syngeneic PVG rats and C57BL6 mice were inoculated with liquid suspensions of UICC chrysotile A asbestos, DQ12 quartz or the inert particulate TiO2. Rats received 10 mg and mice received 2.5 mg dust intraperitoneally on day 0. Injection of the pathogenic dusts asbestos and quartz was associated with a significant reduction in mitogenic response to PHA and Con A detected in splenocytes removed from animals 14 days after inoculation. Injection of TiO2 had no significant effect on splenocyte mitogenesis. Pretreatment of C57BL6 mice with asbestos intraperitoneally also impaired subsequent production of antibody to the protein antigen KLH. These data show that intraperitoneal injection of chrysotile A asbestos and DQ12 quartz had a marked effect on generalized T lymphocyte function. An additional immunomodulatory effect of asbestos injection was shown in C57BL6 mice where in vivo humoral immune responses were suppressed.
J Clin Lab Immunol 1985 Feb
PMID:Immunomodulatory effects of mineral dust. I. Effects of intraperitoneal dust inoculation on splenic lymphocyte function and humoral immune responses in vivo. 398 57

This investigation was performed to assess the bone-to-implant surface contact at fixtures of titanium that either had a standard machine prepared or a TiO2-blasted surface. Five beagle dogs were used in the experiment. Extractions of the premolars were performed in the maxilla. After 4 months of healing, 5 standard machine-prepared fixtures and 5 prepared according to the TioBlast technique were inserted. Two months later another 5 "standard" and 5 TioBlast-prepared implants were inserted. Four months after the first fixture installation, the animals were killed and ground sections prepared from each implant site. Of the 20 implants installed, 19 were successfully incorporated. The mean bone-to-implant surface for "standard" fixtures was about 40% both at the 2 and 4 months observation interval. The corresponding figures for the TioBlast-prepared fixtures were similar during the first 2 months of observation, while subsequently the TioBlast-prepared fixture surface seemed to stimulate to a more close bone-to-implant contact (65%) than the "standard" one.
Clin Oral Implants Res 1994 Dec
PMID:A histomorphometric evaluation of bone-to-implant contact on machine-prepared and roughened titanium dental implants. A pilot study in the dog. 764 Mar 33

Screw-shaped implants with 3 different surface topographies, evidenced visually as well as numerically with an optical profilometer, were inserted in rabbit bone. After a healing period of 12 weeks, a statistically significant higher removal torque was needed to unscrew screws blasted with 25-microns TiO2 particles and screws blasted with 75-microns particles of AI2O3 compared with screws with a turned surface. The histomorphometric evaluation demonstrated a higher percentage of bone-to-metal contact for implants blasted with 25-microns particles of TiO2 compared with the as-machined implants. A greater surface area of bone in threads was found for the turned screws compared with screws blasted with 25-microns TiO2 particles. In the short-term follow-up, there was a better fixation of implants with an average surface roughness of 0.9-1.3-microns and with a homogeneous surface structure than of implants with an average surface roughness of 0.4 microns and with a clear direction of the surface pattern.
Clin Oral Implants Res 1995 Mar
PMID:A histomorphometric and removal torque study of screw-shaped titanium implants with three different surface topographies. 766 64

The initial reactions of two TiO2 surfaces with blood were investigated by short-time exposure to capillary blood and analysis of surface-adsorbed plasma proteins and surface-adhering cells by using immunofluorescence techniques. Antibodies directed against platelet membrane antigen and P-selectin were used to visualize platelet adhesion and activation. Acridine orange and anti-CD11b were used to detect adhesion and activation of polymorphonuclear granulocytes (PMNs). Antibodies against thrombospondin were used as markers for platelet alpha-granules. The fluorescence intensity was quantitated by computer-aided image analysis. Commercially pure, polished sheet titanium was oxidized in two different ways: (1) the natural oxide was dissolved with hydrofluoric acid and a new oxide layer was grown by oxidation in nitric acid, or (2) annealing was performed at 700 degrees C in air. Auger electron spectroscopy and x-ray photoelectron spectroscopy showed that both surfaces had similar composition consisting of TiO2 covered by a carbonaceous surface contamination layer. The thickness of the oxide layer was 4 nm on the acid-oxidized surface and 39 nm on the annealed surface. Optical profilometry and scanning electron microscopy showed that the acid-oxidized surface was rough and the annealed surface was smooth. The fibrinogen/prothrombin-thrombin ratio in the initial protein film differed between the surfaces. The number of adhering platelets was larger at the surface with a high surface concentration of adsorbed fibrinogen. Platelet activation (CD62) and priming of PMNs (CD 11b) were also significantly higher on the acid-oxidized surface. The results indicate that non-self recognition of biomaterials is an array of transient reactions comprising protein-material, protein-cell, and cell-cell interactions.
J Lab Clin Med 1997 Jan
PMID:Adhesion and activation of platelets and polymorphonuclear granulocyte cells at TiO2 surfaces. 901 89

We present an investigation of the physico-chemical surface properties of commercially pure titanium coverslips which were submitted to various treatments designed to optimize their topography in view of application in oral implantology. The surface microroughness, chemical composition and water wettability were analyzed on titanium coverslips prepared by mechanical polishing, acid attack in HCl/H2SO4, after mechanical polishing or sandblasting, and titanium plasma-spray. The chemical composition has been measured by Auger electron spectroscopy. The treatments have no major influence on the surface chemical composition and all the samples display a composition approaching that of TiO2 with minor amounts of carbon, sulfur, silicon and calcium as impurities. The roughness has been measured by scanning force microscopy on an area of 20 microns x 20 microns on each sample. Polished titanium is smooth (peak-to-valley roughness 81 nm), whereas the acid-attacked surfaces exhibit a micro-roughness in the microns range (2100 nm for polished and acid attacked; 3600 nm for sandblasted and acid attacked) which is quite reproducible over large areas of the sample. The acid attacked samples present a subsurface layer which contains hydrogen below the native passivating oxide layer. Water wettability measurement shows that all surfaces are hydrophobic with a slightly higher contact angle for the acid attacked surfaces. The different treatments analyzed in this study essentially influence the surface roughness by preserving the chemical composition and the wettability properties of titanium native oxide surface layer.
Clin Oral Implants Res 1997 Jun
PMID:Influence of surface treatments developed for oral implants on the physical and biological properties of titanium. (I) Surface characterization. 958 65

Screw shaped implants of commercially pure (c.p.) titanium and titanium-6aluminum-4vanadium (Ti6A14V) were blasted with particles of TiO2 of mean sizes of 25 microns (Group I) and 75 microns (Group II) and inserted in rabbit bone for 3 months. The surface roughness of the implants was examined and quantified with an optical scanning 3-dimensional instrument (TopScan 3D system), revealing the two alloy surfaces in each group had similar surface roughness. Biomechanical (removal torque) tests showed the c.p. titanium implants to be significantly more stable in the bone bed than those of Ti6A14V. In Group I, the c.p. titanium implants demonstrated a mean removal torque of 38 N cm while the Ti6A14V demonstrated a mean removal torque of 27 N cm (P = 0.004). Group II implants revealed a mean removal torque of 70 N cm for the c.p. ti and 50 N cm for the alloy samples (P = 0.003). The removal torque values were converted to shear forces/strengths by three calculation methods, based on (a) the entire length of the implant surface in the cortical region, (b) the thickness of the cortical bone measured in close vicinity to the thread peaks and (c) the bone-metal contact length measured on the non-unscrewed neighbouring implants. Group I: (a) the c.p. ti implants revealed a mean shear force of 4 vs a mean of 3 N/mm2 for the alloy samples. Shear strengths based on (b); were 8 for c.p. ti vs 6 N/mm2 for the alloy. The mean shear strength/force if calculated according to (c) revealed 23 for c.p. ti vs 18 N/mm2 for the alloy. Corresponding numbers for Group II; (a) c.p. ti 8 compared to 6 N/mm2 for the alloy, (b) c.p. ti demonstrated a mean value of 17 vs 11 N/mm2 for the alloy. According to method (c); c.p. ti had a mean shear strength of 26 vs 22 N/mm2 for the alloy samples. Histomorphometrical comparisons were performed on 10 microns thick undecalcified ground sections in the light microscope. In both Group I and Group II, the calculations of the mean bone-to-metal contact demonstrated more bone in contact to the c.p. titanium implants than to the Ti6A14V ones. Whereas comparisons of the bone volume inside the threads demonstrated slightly higher bone volumes around the alloy samples, no statistically significant difference was obtained between the two materials histomorphometrically.
Clin Oral Implants Res 1998 Feb
PMID:Quantitative and qualitative investigations of surface enlarged titanium and titanium alloy implants. 959 Sep 39

A specially designed, TiO2-blasted titanium fixture, partially conical and microthreaded, the Astra Tech Fixture ST, was used for rehabilitation of partial edentulism in the posterior mandible. Superior to the mandibular canal 25 fixtures were placed in 10 patients. Fixed metal-ceramic bridges were then performed. After 1-year follow-up, all bridges were found to be clinically stable. The implant survival rate was 100% and the mean marginal bone resorption was 0.05 +/- 0.11 mm.
Clin Oral Implants Res 1998 Oct
PMID:The use of a conical fixture design for fixed partial prostheses. A preliminary report. 983 14

Bioactive coatings on titanium can be prepared by dispersing hydroxyapatite particles into a borosilicate glass enamel doped with TiO2. Adhesion of the coating is obtained when the titanium substrate has been preoxidized before enameling in such a way as to form a continuous TiO2-layer. Adhesion results from the diffusion of this TiO2-layer into the liquid glass during enameling. The evolution of the diffusion zone was followed by scanning electron microscopy and electron probe microanalysis. Adhesion disappears after a critical time of firing which corresponds to the completion of the dissolution of the TiO2-layer by the glass. The borosilicate glass wets the hydroxyapatite particles and adheres strongly to them after cooling.
Clin Mater 1994
PMID:Synthesis of bioactive coatings on Ti substrates using glass enamel. 1015 Jan 75


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