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The thermal effects of a CO2 laser on the external root surface and inside the root canal were studied in vitro by means of computerized infrared (IR) thermography and a digital thermometer. One-hundred-and-eighty tooth roots with single root canals were irradiated internally and externally with laser power set at 0.5, 1, 1.5, 2,3 and4 W. The laser was used in two operating modes: pulsed (pulse 0.5 s) and continuous mode with exposure time of 10 s. Under the conditions of this experiment, temperature rises of between 1.5 and 19.1°C at the external root surface and 1.5 and 12°C inside the root canal and horizontally across the sectioned root surface were recorded. The results obtained with lR camera showed a higher temperature on the external root surface than the digital thermometer during and after lasing the root canal. Scanning electron microscope (SEM) analysis revealed that even low laser energy significantly damaged the external root cementum surfaces. [ABSTRACT FROM AUTHOR]

Purpose: We have assessed the use of an ultrasonic nebulization system (UNS), composed of ultrasonic nebulizer and diffusion dryer filled with charcoal, for the effective delivery of beclomethasone to the airways in a murine asthma model., Methods: Solution of beclomethasone in ethanol was aerosolized using an ultrasonic nebulizer. Passage of the aerosol through a drying column containing charcoal and deionizer produced dry beclomethasone particles. Particles were delivered to BALB/c mice placed in a whole-body exposition chamber 1 h before intranasal challenge with ovalbumine. Efficacy of beclomethasone delivery was evaluated by examining bronchoalveolar lavage fluid (BALF) cytology., Results: Effect of three UNS system parameters on aerosol particle size was investigated. The critical parameter affecting the size of dry particles was beclomethasone concentration in aerosolized solution and solution flow rate while power level of ultrasonic nebulizer generator had no effect. Administration of beclomethasone at calculated dose of 150 microg/kg to mice significantly decreased total cell number and relative eosinophil number in BALF., Conclusions: The UNS system produces a monodisperse aerosol that can be used for inhalative delivery of poorly water soluble substances to experimental animals. The UNS system minimizes formulation requirements and allows rapid and relatively simple efficacy and toxicity testing in animals.

Solid-state properties of piroxicam benzoate, an ester prodrug of piroxicam, were investigated. Samples were prepared by recrystallization from various organic solvents (toluene, ethanol, methanol, ethyl acetate and acetone). Recrystallized samples were characterized by means of FTIR, DSC, TGA, SEM and XRPD. DSC, TGA and XRPD methods confirmed that piroxicam benzoate crystallized in two pseudopolymorphic forms, A and B. Pseudopolymorphic form A was obtained by recrystallization from ethanol and methanol by slow cooling at room temperature and by rapid cooling in an ice-cold bath, and also from toluene by rapid cooling in an ice-cold bath. Pseudopolymorphic form B was obtained by recrystallization from toluene by slow cooling at room temperature.

In the present paper, we studied the effect of natural zeolite clinoptilolite on sphingolipid metabolism in the yeast Yarrowia lipolytica. We also investigated if zeolite addition had any impact on cell shape and size, as well as on the pH alterations during the culture growth. High performance liquid chromatography analysis of sphingoid bases obtained by acid hydrolysis of complex sphingolipids from Y. lipolytica showed that their concentrations markedly rose upon the zeolite addition. The largest increase among the identified molecular species of sphingoid bases was seen in C18 phytosphingosine, whose levels rose 6.2-fold and 22.3-fold after culturing cells for 24 and 36 hours respectively in the presence of finely ground zeolite. pH measurements of the culture medium showed a similarity between pH profiles of control and zeolite-supplemented cells, suggesting that ion-exchange capacity was not probably responsible for the observed change in sphingolipid metabolism. Scanning electron microscopy revealed that zeolite affected cell size and shape. Y. lipolytica cells grown in the absence of zeolite were oval-shaped with an average cell size of 0.7-2.7 microns, whereas when cultured with zeolite, they were round-shaped and larger, having an average cell size of 1.3-2.9 microns.

In this in vitro study, examination of the enamel surface morphology after topical application of an amine fluoride solution with different fluoride (F) content was carried out. Sound human enamel slabs were treated with an amine fluoride solution containing either 1.0, 0.5 or 0.25% F for 3 min. during 3 days. All slabs were examined using scanning electron microscopy and energy-dispersive spectroscopy (SEM/EDS) qualitative analysis. The globular precipitates were revealed in all treated specimens, regardless of F content. The distribution of the deposits was more homogeneous in groups treated with higher concentrations; however, the globules were larger and more cubical in groups treated with lower fluoride concentrations. These larger globules could be less soluble and thus serve as a fluoride reservoir for a more extended period and so they could contribute to the caries preventive effect in professional topical products with lower fluoride concentration. Following the 24-hour treatment with KOH the precipitates could be removed; however, the enamel surfaces covered with the precipitates were less degraded than the untreated enamel. The EDS qualitative analysis showed that the intensities of fluoride signals were increased with the higher concentration of fluoride in an amine fluoride solution, while the intensities of calcium signals were decreased. The enamel surface precipitates were alkali-soluble, but we were not able to demonstrate that they are pure calcium fluoride.

Polymorphic behaviours of paracetamol and propyphenazone and interaction between these two compounds were investigated using differential scanning calorimetry (DSC), X-ray powder diffraction and Fourier transform-infrared (FT-IR)-spectroscopy. Binary mixtures containing various ratios of the compounds were prepared as physical and fused mixtures and analysed by DSC to study their thermal behaviours. Phase diagrams obtained from the melting endotherms of the binary mixtures demonstrated formation of an eutectic mixture at a paracetamol-propyphenazone combination of about 35:65 (w/w) with an eutectic temperature of 56 degrees C. The FT-IR spectroscopy revealed no chemical interaction due to eutectic formation, and a lower degree of crystallinity of the eutectic mixture than individual substances was observed by X-ray powder diffraction analysis. The DSC and X-ray powder diffraction data demonstrated a polymorphic change in propyphenazone as a result of melting of the compound. Tablets, containing both paracetamol and propyphenazone in a combination formulation and prepared using standard wet granulation technology, were found to have physical instability when packed in either polyvinylchloride// aluminium or polyvinylchloride/polyvinyldienechloride// aluminium blisters and stored for one month at 40 degrees C with either 75% relative humidity or without any humidity control. The instability of the tablets was more apparent under the high humidity condition.

Laser effect on enamel is manifested as consequence of temperature changes. Enamel melts, vaporises and a crater, and fissures are formed. Retention surface for anchoring of composite resin was obtained in intact approximal surfaces of premolars with CO2 laser (0.5, 1 and 3 W, sport size 1 and 1.5 mm, 0.2 and 0.5 s). The study results reveal composite and lased enamel interfaces are stronger then composite and inlased enamel (p less than 0.01) but weaker than composite and acid pretreated enamel interface (p less than 0.01).

Bacterial penetration of enamel during initial manifestations of the carious process was studied in intact buccal enamel of 8 impacted third permanent molars. After cleaning them from organic plaque, each buccal plane was cut into five segments, one of them serving as a control specimen and the other four being fixed into slots on partial prostheses of our volunteers. The specimens were left in oral cavity for 7, 14, 21 and 28 days, where they were exposed to the action of cariogenic factors. After removal of the organic plaque, the specimens were broken in two and the bacterial penetration into enamel was observed on the fractured cross-section using scanning electron microscope. In 4 specimens from the group orally exposed during a 7-day period, individual coccoid or bacilliform bacteria were found to have penetrated 5-10 microns deep. The number of bacteria and the depth of their penetration into enamel increased with the duration of oral exposition. Among the specimens orally exposed during 28 days, bacteria were observed to be present both individually and in colonies, penetrating to the depth of 60-90 microns. These bacteria could quite easily communicate with saliva and plaque via the pore system, which allowed them to produce metabolites, including lactic acids. This, in turn, allowed them to penetrate through the enamel, thus altering both the course and rate of the carious process progression.