Penetrating Dye Research Articles

An evaluation of quantitative percussion diagnostics for determining the probability of a microgap defect in restored and unrestored teeth: A prospective clinical study

Statement of problemCurrent dental diagnostics are image based and cannot detect a structural microgap defect such as a crack in a tooth. Whether percussion diagnostics can effectively diagnose a microgap defect is unclear. PurposeThe purpose of the present study was to determine from a large multicenter prospective clinical study whether quantitative percussion diagnostics (QPD) could detect structural damage in teeth and whether a probability of its presence could be provided. Material and methodsA nonrandomized prospective and multicenter clinical validation study with 224 participants was performed in 5 centers with 6 independent investigators. The study used QPD and the normal fit error to determine whether a microgap defect was present in a natural tooth. Teams 1 and 2 were blinded. Team 1 tested teeth scheduled for restoration with QPD, and Team 2 disassembled the teeth aided by a clinical microscope, transillumination, and a penetrant dye. Microgap defects were documented in written and video formats. Controls were participants without damaged teeth. The percussion response from each tooth was stored on a computer and analyzed. A total of 243 teeth were tested to provide approximately 95% power to test the performance goal of 70%, based on an assumed population overall agreement of 80%. ResultsRegardless of the collection method, tooth geometry, restoration material used, or restoration type, the data on detecting a microgap defect in a tooth were accurate. The data also reflected good sensitivity and specificity consistent with previously published clinical studies. The combined study data showed an overall agreement of 87.5% with a 95% confidence interval (84.2 to 90.3), beyond the 70% predetermined performance goal. The combined study data determined whether it was possible to predict the probability of a microgap defect. ConclusionsThe results showed that the data on detecting microgap defects in a tooth site were consistently accurate and confirmed that QPD provided information to aid the clinician in treatment planning and early preventative treatment. QPD can also alert the clinician of probable diagnosed and undiagnosed structural problems via the use of a probability curve.

The Effects of Cyclic Loading and Motion on the Implant-Cement Interface and Cement Mantle of PEEK and Cobalt-Chromium Femoral Total Knee Arthroplasty Implants: A Preliminary Study.

This study investigated the fixation of a cemented PEEK femoral TKA component. PEEK and CoCr implants were subjected to a walking gait cycle for 10 million cycles (MC), 100,000 cycles or 0 cycles (unloaded control). A method was developed to assess the fixation at the cement–implant interface, which exposed the implants to a fluorescent penetrant dye solution. The lateral condyles of the implants were then sectioned and viewed under fluorescence to investigate bonding at the cement–implant interface and cracking of the cement mantle. When tested for 100,000 cycles, debonding of the cement–implant interface occurred in both PEEK (61%) and CoCr (13%) implants. When the duration of testing was extended (10 MC), the percentage debonding was further increased for both materials to 88% and 61% for PEEK and CoCr, respectively. The unloaded PEEK specimens were 79% debonded, which suggests that, when PEEK femoral components are cemented, complete bonding may never occur. Analysis of cracks in the cement mantle showed an absence of full-thickness cracks in the unloaded control group. For the 100,000-cycle samples, on average, 1.3 and 0.7 cracks were observed for PEEK and CoCr specimens, respectively. After 10 MC, these increased to 24 for PEEK and 19 for CoCr. This was a preliminary study with a limited number of samples investigated, but shows that, after 10 MC under a walking gait, substantial debonding was visible for both PEEK and CoCr implants at the cement–implant interface and no significant difference in the number of cement cracks was found between the two materials.

Evaluation of Welded Joints in P91 Steel under Different Heat-Treatment Conditions

P91 steel has been of interest to many researchers over the past two decades. This interest is because this steel has very interesting characteristics for application in power plants, where it is common to have pipes that need to support steam at temperatures between 570 and 600 °C, and at pressures in the range of 170 to 230 bar. These working conditions are quite severe for most common steels, requiring increased high-temperature mechanical strength as well as high creep resistance. The manufacture of these pipes normally includes welding operations, which must preserve the main characteristics of this type of steel. This justifies the concern of the researchers to ensure the best welding conditions so that the preservation of the properties of these steels becomes possible. The present work intends to depict the best results obtained varying the heat-treatment conditions applied to weldments made on heat-resistant steel P91. This steel usually takes the designation SA 213 T91 (seamless tube) or SA 335 P91 (seamless pipe), according to ASME II, as well as the designation X10CrMOVNb9-1 according to EN 10216-2. The purpose of this study is to compare the behavior of pipe welding under different post-welding heat-treatment (PWHT) conditions. One of them is performed with thermal cycles (preheating, post-heating, and the post-weld heat treatment) in agreement with most construction codes and standard rules. The second one is performed without any thermal cycle before and after welding. Both welds were made by the same process, TIG (Tungsten Inert Gas, or GTAW—Gas Tungsten Arc Welding) in the horizontal position (2G according to ASME IX) and the same welding parameters. In order to evaluate the results obtained in the welds, microstructure analyses, hardness measurements, bending tests, and tensile tests at room and high temperature (600 °C) have been performed. Other tests were also carried out according to the quality procedures, such as visual, penetrant dye, and X-ray tests. Regarding the different strategies used in the heat treatments, the best results have been obtained using a strategy similar to the one currently in use and recommended by construction codes and steel manufacturers but excluding the phases’ transformation time, and it was possible to observe that the tensile strength is impaired by about 2% to 9% at room and elevated temperatures, respectively; the elongation is reduced by 39% at room temperature but keeps a good performance at elevated temperature; the hardness profile is very similar at both temperatures; the microstructure presented is compatible with the requirements; and no cracking trend has been reported. Thus, a new strategy for the welding heat treatment of grade 91 steels was drawn, saving energy and processing time.

Enhanced Cellular Entry and Efficacy of Tat Conjugates by Rational Design of the Auxiliary Segment

Conjugation with a cell penetrating peptide such as Tat presents an effective approach to improve the intracellular accumulation of molecules with low membrane permeability. This strategy, however, leads to a reduced cellular entry of molecules that can cross cell membrane effectively. We report here that covalent linkage of an additional hydrophobic unit that mimics a hydrophobic domain near the Tat sequence can further improve the cellular uptake of the parental conjugate into cancer cells regardless of the membrane permeability of the unconjugated molecule. Both fluorescent imaging and flow cytometry measurements confirmed the effect of palmitoylation on the increased internalization of the Tat conjugates with either 5-carboxyfluorescein (5-FAM), a nonmembrane penetrating dye, or doxorubicin, an anticancer cancer drug that can readily diffuse across cell membranes. In the case of the Tat–doxorubicin conjugate, palmitoylation improves the conjugate’s anticancer activity in both drug sensitive and resistant cervical cancer cell lines. We further demonstrate that modification of a Tat–5-FAM conjugate with a hydrophobic quencher could not only efficiently quench the fluorescence outside of cancer cell but also facilitate its entry into MCF-7 breast cancer cells. These results highlight the importance of rational molecular design of using peptide conjugation chemistry in cancer therapeutics and diagnostics.

Processing and performance of self-healing materials

Two self-healing methods were implemented into composite materials with self-healing capabilities, using hollow glass fibres (HGF) and microencapsulated epoxy resin with mercaptan as the hardener. For the HGF approach, two perpendicular layers of HGF were put into an E-glass/epoxy composite, and were filled with coloured epoxy resin and hardener. The HGF samples had a novel ball indentation test method done on them. The samples were analysed using micro-CT scanning, confocal microscopy and penetrant dye. Micro-CT and confocal microscopy produced limited success, but their viability was established. Penetrant dye images showed resin obstructing flow of dye through damage regions, suggesting infiltration of resin into cracks. Three-point bend tests showed that overall performance could be affected by the flaws arising from embedding HGF in the material. For the microcapsule approach, samples were prepared for novel double-torsion tests used to generate large cracks. The samples were compared with pure resin samples by analysing them using photoelastic imaging and scanning electron microscope (SEM) on crack surfaces. Photoelastic imaging established the consolidation of cracks while SEM showed a wide spread of microcapsules with their distribution being affected by gravity. Further double-torsion testing showed that healing recovered approximately 24% of material strength.

Effects of Dall-Miles Cables on the Cement Mantle in Total Hip Arthroplasty: A Cadaveric Study

Dall-Miles cables are widely used for trochanteric re-attachment in hip arthroplasty, but their effects on the cement mantle have not been reported. We have carried out an ex vivo study to investigate the influence of cables on the mantle. Charnley femoral components were implanted in eight proximal human femora using Palacos cement. Wires (control group, n=4) or 2mm stainless steel Dall-Miles cables (n=4) were passed through holes drilled in the proximal femur before the cement was introduced. The wires or cables were tightened using the appropriate instruments after the cement had hardened. The specimens were sectioned using a diamond saw, and examined by scanning electron microscopy and light microscopy before and after staining with penetrant dye. Deformation of the strands at the tension edge of each cable, with debonding from the cement in two specimens, was observed. There was no damage to cement at the compression edge. Tensioning of Dall-Miles cables passing through Palacos cement does not appear to damage the mantle.

Mechanism of spallation in platinum aluminide/electron beam physical vapor-deposited thermal barrier coatings

The spallation failure of a commercial thermal barrier coating (TBC), consisting of a single-crystal RENE N5 superalloy, a platinum aluminide (Pt-Al) bond coat, and an electron beam-deposited 7 wt pct yttria-stabilized zirconia ceramic layer (7YSZ), was studied following cyclic furnace testing. In the uncycled state and prior to deposition of the ceramic, the Pt-Al bond-coat surface contains a cellular network of ridges corresponding to the underlying bond-coat grain-boundary structure. With thermal cycling, the ridges and associated grain boundaries are the sites of preferential oxidation and cracking, which results in the formation of cavities that are partially filled with oxide. Using a fluorescent penetrant dye in conjunction with a direct-pull test, it is shown that, when specimens are cycled to about 80 pct of life, these grain-boundary regions show extensive debonding. The roles of oxidation and cyclic stress in localized grain boundary region spallation are discussed. The additional factors leading to large-scale TBC spallation are described.

A fiber-optic setup for quantification of root surface demineralization.

A fiber-optic fluorescence observation (FOFO) technique has been developed for the quantification of demineralized root dentin. The method was tested on 40 specimens of in vitro demineralized parts of human root dentin. Fluorescein sodium salt was used as a penetrating dye. The fluorescein sodium salt was excited using light around 465 nm. The fluorescence signal around 527 nm measured for demineralized dentin was corrected for lamp output and then divided by the corrected fluorescence signal for the sound control dentin on the same root, resulting in a FOFO-value. FOFO-values correlate linearly (r = 0.91) with mineral loss measured by transverse microradiography. Therefore, it was concluded that the FOFO-technique provides a good, non-destructive measure of the severeness of in vitro demineralized human root dentin, and is applicable on bulk dentin. Future work on natural lesions in vivo will be needed to investigate the applicability of the technique in a clinical situation.

Evaluation of Sodium Fluorescein for Quantitative Diagnosis of Root Caries

The diagnosis of root caries, in particular the judgment of the activity of a visually observed lesion, is difficult. Quantitative determination of lesion severity would allow the lesion to be monitored with time, so that an indication of lesion activity could be obtained. This paper describes a step in the development of a method that provides such a quantitative determination. Specifically, fluorescein sodium salt is used as a penetrating dye, the subject of study being the relationship between dye concentration and porosity in demineralized root dentin. Fourteen human third molars were demineralized in vitro (lactic acid CMC-gel, pH 5; in each of 6 groups for 4, 7, 11, 14, 18, and 21 days). Fluorescein sodium salt (0.2 g/L) was applied for 2 min. Thin slices (+/- 130 microns) were cut from the root surfaces without water cooling. The dye fluorescence radiance in the demineralized dentin was determined by means of a micro-Raman spectroscope and compared with the mineral loss profiles measured with transverse microradiography (TMR). The TMR data were corrected for the difference in measurement area between the two measurement systems. Corrected TMR profiles were compared with the corresponding fluorescence scans, showing linear correspondence. The correlation coefficient was r = 0.96. We conclude that, after uptake of fluorescein sodium salt for 2 min, the dye concentration in an artificially produced root-surface caries lesion is proportional to the amount of mineral lost from that lesion.

The Effect of Environmental Moisture and Temperature on the Physical Stability of Effervescent Tablets in Foil Laminate Packages Containing Minute Imperfections

AbstractThe effect of environmental moisture on the physical stability of effervescent tablets in foil laminate packages containing microscopic imperfections (openings) was examined. Packaged tablets were stored at different relative humidity (RH) and temperature conditions and evaluated for physical stability at predetermined time intervals. Physical stability was assessed by noting if the tablet components reacted prematurely to yield soft tablets during storage. A penetrating dye solution test was used to determine if the foil packages contained imperfections which might allow transmission of moisture. The results of the investigation indicated that absolute moisture integrity of the foil package is required for product stability.

ACTIVATION VOLUME FOR THE DIFFUSION OF DISPERSE DYE IN NYLON 6

The effect of pressure on the diffusion coefficient, D, of seven disperse dyes in nylon 6 sheet has been investigated. D was measured at 90°C with the multiple membrane placed in the aqueous solutions of the dyes under pressures up to 3kbar. The values of In D decreased linearly with increasing pressure, from which the activation volume, ΔV_??_, for the diffusion was estimated to be 20.2-33.2cm3/mol for the seven dyes. The ΔV_??_ values were compared with the intrinsic volumes, Vw's, of the dyes. It was found that ΔV_??_ increases almost linearly with increasing Vw for the series of the anthraquinone and azo dyes. It was also found that ΔV_??_for the anthraquinone dye is larger than that for the azo dye if they are compared at the same Vw. These findings are in accordance with those obtained previously for poly (ethylene terephthalate).The results obtained above were discussed in terms of ΔV_??_EH, ΔV_??_W and ΔV_??_i, where ΔV_??_EH is the volume change on the formation of the Eyring's hole, ΔV_??_W is the change in VW on the activation and ΔV_??_i is the volume change on the activation due to the _??_teraction of the penetrant dye with the surrounding swollen polymer matrix.

Transverse Distribution of Phospholipids in Organelle Membranes from Ricinus communis L. var. Hale Endosperm

Phospholipase A(2) (Naja naja), the nonpenetrating dye trinitrobenzene sulfonate, and the penetrating dye dinitrofluorobenzene, were used to determine the transmembrane distributions of phospholipids of mitochondria and glyoxysomes isolated from endosperm tissue of castor bean (Ricinus communis L. var. Hale). These studies indicated that the phospholipid distributions were distinctly asymmetric in the accessible (reacted with the probes without total membrane disruption by detergents) pools of the glyoxysomal and inner mitochondrial membranes, but more nearly symmetric in the outer mitochondrial membrane. However, significant quantities of the phospholipids of the mitochondrial membranes were inaccessible to the probes used. An increased accessibility of the phospholipids of all membranes following Triton X-100 dispersion was found, and protein to phospholipid ratios in organelle membranes were found to correlate inversely with the accessibility of the phospholipids to the probes. The inaccessible phospholipids may be involved in lipid-protein interactions.

ROLE OF DYE MOLECULES REMAINING OUTSIDE THE CELL DURING PHOTODYNAMIC INACTIVATION OF ESCHERICHIA COLI IN THE PRESENCE OF ACRIFLAVINE

Abstract— Photodynamic inactivation of cells is caused by damage to the regions proximal to the cell envelope or to the DNA via a singlet oxygen mechanism. For penetrating dyes the possibility of either type of damage remains. The contribution of a penetrating dye. acriflavine. remaining outside E. coli B/r cells during irradiation. towards photodynamic inactivation was investigated. It was found that this contribution was either nil or negligible.

LOCATING LEAKS IN EGG PASTEURIZERS

The U. S. Department of Agriculture tests for leaks in egg pasteurizers indicate only whether a leak is or is not present. Three tests for locating leaks in plate heat exchangers, after leaks have been indicated, have been evaluated from laboratory and plant trials. For an entire regeneration or cooling section a test using diazo paper and ammonia gas is feasible. Individual plates removed from the press can be tested by using diazo paper and ammonium hydroxide. A penetrant dye and developer test will confirm the exact location of a hole after its possible location has been reduced to a small area.

Desalination Features in Natural Sea Ice

Salinity profiles of young sea ice are presented which show salinity differences of the order of 2‰ to 3‰ within a ~3 cm. distance, horizontally as well as vertically. This ice is also shown, by use of a penetrating dye, to be very permeable which encumbers any attempt to explain such pronounced salinity variations. Two generations of brine-drainage features are described; the first is inherited from the liquid and the later-generation channels develop from brine-pocket and Tyndall-figure migration.It is proposed that at least part of the brine contained in the ice mass migrates downward in the following way: cold dense brine cascades from higher levels, causing the more dilute, warmer brine at lower levels to partially freeze. This would also account for some of the local variations in salinity.

Desalination Features in Natural Sea Ice

Salinity profiles of young sea ice are presented which show salinity differences of the order of 2‰ to 3‰ within a ~3 cm. distance, horizontally as well as vertically. This ice is also shown, by use of a penetrating dye, to be very permeable which encumbers any attempt to explain such pronounced salinity variations. Two generations of brine-drainage features are described; the first is inherited from the liquid and the later-generation channels develop from brine-pocket and Tyndall-figure migration.It is proposed that at least part of the brine contained in the ice mass migrates downward in the following way: cold dense brine cascades from higher levels, causing the more dilute, warmer brine at lower levels to partially freeze. This would also account for some of the local variations in salinity.

An in vitro method for demonstrating the effects of various cutting instruments on tooth structure

Results of this study indicate that alteration of the hard tissues of teeth can be induced by the cutting instruments commonly utilized in everyday operative procedures. Two hundred human teeth in groups of twenty were used to study the effects on the teeth when cavities were prepared with commonly used cutting instruments operated at different speeds. A fluorescent penetrating dye was utilized to reveal the extension of pre-existing defects or the initiation of additional defects. All of the instruments used in this study, with each of the different cutting tips, produced cracks in some teeth. Some instruments produced the effect with greater frequency than others. The frequency and severity of crazing in each group did appear to be influenced by the type of cutting tip used with the rotating instruments. However, the differences noted with various handpieces should not be interpreted as recommendations for the specific instrument. Rather, the investigation illustrates that a surface phenomenon is produced, the exact clinical significance of which is as yet unknown. In order to establish the clinical significance, further investigation along similar lines is necessary. The test method has been demonstrated, and its application to in vivo studies is suggested.