Effect of TiF4 solutions on bacterial growth in vitro and on tooth surfaces

The purpose of this study was to assess the antimicrobial effect of TiF4 as compared with equimolar solutions of NaF, APF, and SnF2 and to evaluate the effect, if any, on bacterial growth on topically treated tooth surfaces. In an in vitro study, paper discs impregnated with 20 microliters of equimolar solutions of SnF2, NaF, APF, and TiF4 were placed on blood agar plates seeded with Streptococcus mutans and Bacteroides gingivalis. Sterile saline was used as control. Similar growth inhibition zones were found for all fluorides. In the second part of the study six volunteers carried intraoral appliances containing enamel and root surface specimens treated with 1% TiF4 and untreated specimens for 18 h. Scanning electron microscopic examination of the experimental tooth surfaces showed great variation in bacterial growth between subjects, but no systematic difference between fluoride-treated and untreated specimens. Bacteria from test and control specimens were grown under aerobic and anaerobic conditions on blood agar and on mitis salivarius agar. Colony-forming unit counts showed great interindividual variations, but no differences could be observed between treated and untreated enamel or root surfaces. Thus, the hypothesis that the presence of a Ti-rich coating may influence bacterial colonization on TiF4-treated tooth surfaces could not be substantiated.

Toxicology and carcinogenesis studies of dietary titanium dioxide-coated mica in male and female Fischer 344 rats

Male and female Fischer 344 rats were fed diets containing 0, 1.0, 2.0, or 5.0% titanium dioxide (TiO2) coated mica for up to 130 wk. This dosage regimen produced no consistent or biologically important changes in survival, body weight gains, hematologic or clinical chemistry parameters or histopathology. Under the conditions of this 130 wk feeding study there was no evidence that TiO2-coated mica produced either toxicologic or carcinogenic effects at dietary concentrations as high as 5.0%. The results suggest that dietary exposure to TiO2-coated mica does not pose a significant human health hazard.

[Serum lysozyme and copper levels in rats after the administration of dust]

Changes in the content of lysozyme and copper were studied in the blood serum of rats in four time intervals (1, 2, 12, and 24 weeks) after administration of 50 mg TiO2, Sio2 or coal dust and the copper content was also studied 12 weeks after administration of 3 industrial dusts. The obtained results were supplemented by histopathological examinations and in the 12-week interval by the determination of the lung wet weight. The lysozyme content was statistically significantly increased compared to controls practically over the whole time course with differences in the level of the response to SiO2 in comparison with the response to TiO2 and coal. With the exception of the first interval, the serum copper level was statistically significantly increased only after quartz dust administration. The obtained results were compared with literary data and findings reported from clinical practice.

In vivo uptake and retention of fluoride after a brief application of TiF4 to dentin

The purpose of this study was to examine the long-term retention of F and Ti in dentin after a brief application of 1% TiF4. Six facets of exposed dentin in each of four beagle dogs were treated for 10 sec or 1 min with a 1% solution of TiF4. Four control facets in a fifth dog were left untreated and extracted after 12 weeks. The TiF4-treated teeth were harvested after 4, 8, and 22 weeks and analyzed for F and Ti with an electron microprobe. The F concentrations in dentin surfaces of specimens retained in the mouth for 4, 8, and 22 weeks were after the 10-sec treatment 0.48% +/- 0.24, 0.51% +/- 0.20, and 0.56% +/- 0.20, respectively, and after the 1-min treatment 0.64% +/- 0.20, 0.66% +/- 0.18, and 0.71% +/- 0.19. High concentrations of Ti were found at the specimen surfaces in all groups. None of the control specimens showed F or Ti contents above the detection limits for the method used. The results showed that a very brief application of 1% TiF4 deposited high concentrations of F and Ti which were retained for at least 22 weeks.

Effects of TiF4 solutions on root surfaces in vitro after different application periods

Topical application of aqueous solutions of TiF4 to root surfaces has been shown to result in a rapid uptake of fluoride. The purpose of this study was to assess whether the application period and/or the ionic strength of the TiF4 solution can be reduced without a corresponding reduction in the fluoride uptake. Root halves from human teeth were exposed to (a) 1% TiF4 for 10 sec and 1, 2, and 4 min, and (b) 3.4% TiF4 for the same application periods. Root surface areas protected by nail polish served as controls. Transverse ground sections through the treated root surface areas were then prepared and analyzed for F by electron microprobe analysis. Most treated specimens showed F concentrations in the 0.60-1.94% range, whereas control surfaces contained less than 0.30%. Similar F concentrations were found in the surfaces treated with the two solutions. Reducing the application period resulted in a shallower penetration of F into the hard tissue but only a slight reduction of the F concentration in the surface layer. High concentrations of Ti were found on the surface of all treated specimens. This shows that both the application period and the ionic strength of TiF4 solutions can be considerably reduced and still enable a high uptake of fluoride. The results indicate that TiF4 may be an efficacious agent for F application to root surfaces under clinical conditions.

Lung response to test toner upon 2-year inhalation exposure in rats

SPF F-344 rats were exposed 6 h/day 5 days/wk for up to 24 months to a special test toner at 0, 1, 4 and 16 mg/m3 or TiO2 at 5 mg/m3, or SiO2 at 1 mg/m3, by the inhalation route. The animals were kept for an additional 6 weeks in filtered air. Surviving animals were sacrificed at 25.5 months after start of exposure. Life-span and causes of death were independent of treatment and in accordance with published values. No evidence for systemic toxicity or any upper-respiratory system effects were found in the toner-exposed groups. The incidence of lung tumors was comparable in the control, 3 toner and TiO2-exposed groups. An incidence of 18%, combined benign and malignant tumors was observed in the quartz-treated rats. A slight to moderate degree of fibrosis was observed at the toner high exposure level in all animals, while a very slight degree of fibrosis was noted in 20% of the animals at the toner middle (4 mg/m3) exposure level. The fibrogenic potency of the test toner was calculated to be comparable to TiO2. No pulmonary changes were seen at the toner low (1 mg/m3) and environmentally most relevant exposure level.

The biological response to titanium and titanium-aluminium-vanadium alloy particles. II. Long-term animal studies

The long-term tissue reactions to particulate titanium and titanium-aluminium-vanadium alloy were investigated by the intra-articular injection of material into the knee joints of mice. The tissue response was studied over a period of 2 to 52 weeks. In general, both materials were well tolerated, there was no evidence of necrosis and only a slight thickening of the synovium occurred around particles. Multinucleated giant cells were only rarely seen and no palpable tumours formed in any animal at any site.

Activity of titanocene dihalides against a human colon carcinoma heterotransplanted to athymic mice

The antitumor activity of cis-diamminedichloroplatinum (II) and of two metallocene derivatives, titanocene dichloride (C5H5)2TiCl2 and titanocene dibromide (C5H5)2TiBr2, was investigated against a human colon adenocarcinoma heterotransplanted to athymic mice. The substances were administered at various doses on a Q2DX5 or a Q3DX5 schedule. Whereas cis-diamminedichloroplatinum (II) induced an only marginal tumor-inhibiting effect, both titanocenes markedly suppressed tumor development (T/C values: 23-40%) and caused stagnation and relative decrease of tumor growth, when they were applied in subtoxic doses far below the LD10 level. The results are remarkable with respect to the general insensitivity of human colorectal carcinomas to cytostatic agents.

Transmigration of titanium dioxide (TiO2) particles in rats after inhalation exposure

Titanium dioxide (TiO2) has been used extensively in the manufacturing of white pigment and has generally been regarded as a nuisance dust in animals and man. After inhalation exposure, little is known about transmigration routes and potential toxic effects of translocated particles in other organs. In order to answer these questions, rats were exposed to TiO2 by inhalation exposure at concentrations of 0, 10, 50, and 250 mg/m3 for 2 years. A few free particles were retained in the nasal and tracheobronchial epithelium without any cellular damage, but aggregates of dust-laden macrophages (dust cells) were found in the lymphoid tissue of the submucosa. Inhaled particles were mostly engulfed by alveolar macrophages and confined sharply to the alveolar duct region at 10 and 50 mg/m3, while dust cells were scattered throughout alveoli at 250 mg/m3. A fraction of the inhaled particles was retained in the membranous pneumocytes and interstitial macrophages. A dense accumulation of dust cells was found in the perivascular and peribronchial lymphoid tissue. Some dust cells entered peribronchial lymphatics or pulmonary blood vessels and the general circulation. Dust cells in the hyperplastic peribronchial lymphoid tissue were exposed directly in the luminal surface of the airways and were subsequently eliminated via airways. Massive dust deposition was observed in the tracheobronchial lymph nodes. Dust transmigration was markedly reduced in the cervical lymph nodes, and only a trace amount of dust particles was found in the mesenteric lymph nodes. Some dust cells entered either blood or lymphatic vessels in the lymph nodes and then migrated into the general circulation. The incidence of extrapulmonary dust deposition in the liver or spleen was increased in a dose-related fashion similar to the lung dust burden. Since there was no tissue response to translocated particles in the lymph nodes, spleen, or liver, potential adverse health effects appear to be negligible.

Microprobe and SEM analysis of surface coatings on caries-like lesions in enamel after metal ion mordanting and APF application

The production of tenacious surface coatings on enamel after metal ion mordanting followed by APF has been reported to prevent caries-like lesion initiation in vitro. In this study, similar surface coatings, which may be responsible for the inhibition of lesion progression, were examined using SEM and microprobe analysis. Relatively thick, even surface coatings which were in intimate contact with the enamel surface of caries-like lesions were seen after zirconium and iron (ferric) pre-treatment, but a thinner and unevenly distributed coating was seen after titanium pre-treatment. This latter coating was similar to that seen after APF treatment alone. Fluoride concentrations on the surface and in the subsurface of caries-like lesions were similar for all treatment groups. The surface coatings after zirconium and iron mordanting may be responsible for the greater inhibition of lesion progression than that seen after both titanium pre-treatment and APF treatment alone.

Titanium retention in mice

Intraperitoneal (i.p.) and intravenous (i.v.) injection of 44Ti in a chloride solution into mice produced no detectable translocation in body fluids. There was no obvious interorgan exchange up to 16 days after injection. The whole body biological retention half-lives had a mean of 642 days for both routes, another indication of 44Ti's insolubility in body fluids. Absorption from the gastrointestinal (g.i.) tract after administration by stomach tube was negligible. The threshold limit value (TLV) for titanium in air, based upon nuisance dust, is acceptable based upon the results of this study.

Titanium and fluoride concentrations in titanium tetrafluoride and APF treated enamel

Greater fluoride concentrations were obtained in enamel treated with phosphate/fluoride solutions than in that treated with TiF4 at similar pH's (1.0) and F concentrations (0.6M F and 1.6M F). However, fluoride solution without added phosphate at pH 1.0 and 1.6M F concentration produced lower fluoride concentrations in enamel than in TiF4 treated enamel. It is proposed that in TiF4 treated enamal the fluoride uptake may be dependent upon the amount of Ti introduced into the enamel.

Absorption, excretion, and tissue deposition of titanium in sheep

Titanium metabolism was measured in three 18 kg lambs each fed 450 g chopped hay daily. Two of the lambs were dosed orally and one intravenously with 3 muCi titanium-44 each. Clearance of the intravenous dose was extremely slow; after oral administration, however, no titanium-44 was detected in blood plasma for 48 h. Over 96% of the oral dose was recovered in feces and digestive tract contents. Titanium-44 absorption, estimated from total carcass recovery and by comparison of concentrations in internal organs of orally and intravenously dosed lambs, was less than .5%. Fecal titanium could be a satisfactory index of soil ingestion by grazing ruminants.

Electron microprobe analysis of particle deposited in lungs

A technique that is based on the combined use of a conventional transmission electron microscope and a conventional electron probe x-ray microanalyzer permits an unambiguous identification of titanium dioxide (TiO2) particles in lung tissue and cells. Quite probably, many other inorganic particles can be identified with the use of this technique.

Effect of enamel solubility reducing agents on erosion in the rat

Three experiments performed on Osborne-Mendel rats tested the effects on erosion of the topical application of aluminum, cerium and titanium salts as well as sodium fluoride and sodium mono-fluorophosphate. In two experiments the compounds were applied during the erosion period and in a third trial, the test substances were applied prior to exposure to the erosive agent which was fermented apple juice. While cerium had no significant effects on erosion, aluminum fhloride and titanium chloride significantly increased the severity of erosive tooth destruction. Only sodium fluoride and sodium mono-fluorophosphate were effective in preventing erosion.