In Vitro and In Vivo Antibacterial Activities of Patchouli Alcohol, a Naturally Occurring Tricyclic Sesquiterpene, against Helicobacter pylori Infection.

This study further evaluated the in vitro and in vivo anti-Helicobacter pylori activities and potential underlying mechanism of patchouli alcohol (PA), a tricyclic sesquiterpene. In the in vitro assay, the capacities of PA to inhibit and kill H. pylori were tested on three standard strains at different pH values and on 12 clinical isolates. The effects of PA on H. pylori adhesion (and its alpA, alpB, and babA genes), motility (and its flaA and flaB genes), ultrastructure, and flagellation were investigated. Moreover, the H. pylori resistance to and postantibiotic effect (PAE) of PA were determined. Furthermore, the in vivo effects of PA on H. pylori eradication and gastritis were examined. Results showed that MICs of PA against three standard strains (pH 5.3 to 9) and 12 clinical isolates were 25 to 75 and 12.5 to 50 µg/ml, respectively. The killing kinetics of PA were time and concentration dependent, and its minimal bactericidal concentrations (MBCs) were 25 to 75 µg/ml. In addition, H. pylori adhesion, motility, ultrastructure, and flagellation were significantly suppressed. PA also remarkably inhibited the expression of adhesion genes (alpA and alpB) and motility genes (flaA and flaB). Furthermore, PA treatment caused a longer PAE and less bacterial resistance than clarithromycin and metronidazole. The in vivo study showed that PA can effectively eradicate H. pylori, inhibit gastritis, and suppress the expression of inflammatory mediators (COX-2, interleukin 1ß, tumor necrosis factor alpha, and inducible nitric oxide synthase [iNOS]). In conclusion, PA can efficiently kill H. pylori, interfere with its infection process, and attenuate gastritis with less bacterial resistance, making it a potential candidate for new drug development.

Predicting the maturity of haemodialysis arteriovenous fistulas with colour Doppler ultrasound: a single-centre study from China.

AIM: To explore the optimal vascular diameter and blood flow measured by ultrasound to predict fistula maturity in Chinese patients. MATERIALS AND METHODS: One hundred and thirty-two patients were enrolled in the study. The blood flow and the diameters of the brachial artery, radial artery, and cephalic vein were analysed according to clinical outcomes. The performances of blood flow, cephalic vein diameter, and the two factors combined in predicting fistula maturity were evaluated and the optimal cut-off values for Chinese patients were determined. RESULTS: During a 6 month follow-up, 113 fistulas were classified as mature and 19 fistulas were classified as failure. In both groups, the diameters of the brachial and radial arteries increased gradually within 2 weeks post-surgery (p<0.05), and cephalic vein diameter and blood flow increased within 4 weeks post-surgery (p<0.05). The blood flow of the failure group was significantly lower than that of the mature group from the first day after creation. The area under the receiver operating characteristic (ROC) curve was 0.95 (529 ml/min, the optimal cut-off value) for blood flow, 0.83 (5.2 mm) for cephalic vein diameter, and 0.96 for the two factors combined in predicting fistula maturity. CONCLUSIONS: For Chinese patients, blood flow >529 ml/min could be used to predict fistula maturity and cephalic vein diameter >5.2 mm could be a supplement when necessary.

FDI report on adverse reactions to resin-based materials.

Resin-based restorative materials are considered safe for the vast majority of dental patients. Although constituent chemicals such as monomers, accelerators and initiators can potentially leach out of cured resin-based materials after placement, adverse reactions to these chemicals are rare and reaction symptoms commonly subside after removal of the materials. Dentists should be aware of the rare possibility that patients could have adverse reactions to constituents of resin-based materials and be vigilant in observing any adverse reactions after restoration placement. Dentists should also be cognisant of patient complaints about adverse reactions that may result from components of resin-based materials. To minimise monomer leaching and any potential risk of dermatological reactions, resin-based materials should be adequately cured. Dental health care workers should avoid direct skin contact with uncured resin-based materials. Latex and vinyl gloves do not provide adequate barrier protection to the monomers in resin-based materials.

Variation of depth of cure and intensity with distance using LED curing lights.

OBJECTIVES: The purpose of the study was to determine the correlation between intensity of light-emitting diode (LED) and tungsten-halogen light sources, and depth of cure of a resin composite at different distances. METHODS: Four LED curing lights (Flashlite 1001, Freelight 2, Smartlite IQ and Ultralume 5) and one tungsten halogen (Optilux 501, with 8 and 11 mm tips) were evaluated. Intensity was measured according a modified ISO Standard 10650 at distances of 0, 2, 4, 6, 8, 10 mm between the light tip and detector. Depth of cure (DOC) of TPH Spectrum shade A2 was measured according to the international standard ISO 4049 at the same distances. RESULTS: For all lights, intensity decreased as distance increased. The authors documented a logarithmic correlation between intensity and distance for all lights except the Smartlite IQ, Ultralume 5 and the Optilux 501 with the 11 mm tip, which showed a linear relationship between intensity and distance. All lights demonstrated a logarithmic correlation between intensity and DOC, and a linear correlation between DOC and distance. Smartlite IQ and Optilux 501 (11 mm tip) also had the least reduction in intensity and DOC at 10 mm. SIGNIFICANCE: Clinicians often an experience difficulty placing the light tip close to the resin surface when curing resin composites. While both intensity and DOC decrease with increasing distance, the relationship between these factors and distance may not be similar for all lights and may depend on the characteristics of individual lights.

Evaluating amalgam separators using an international standard.

BACKGROUND: Most amalgam particles generated during placement and removal of amalgam restorations are captured by chair-side traps and suction system traps and filters. Particles not captured can end up in the wastewater discharged from the dental office. Environmental initiatives to reduce the discharge of mercury-containing products such as dental amalgam waste into the environment have sparked interest in the use of amalgam separators. METHODS: The authors used International Organization for Standardization (ISO) Standard 11,143 for Amalgam Separators in a laboratory test to evaluate the amalgam removal efficiency of 13 commercially available amalgam separators and two commercially available filtration devices not marketed as amalgam separators but that have the potential to be used as such. RESULTS: All 13 amalgam separators and the two filtration devices exceeded the ISO Standard 11,143 requirement of 95 percent amalgam removal efficiency. The authors found statistical differences in the efficiency of the separators and filtration devices. No differences were found between the "empty" and "full" conditions for each separator. CONCLUSION AND CLINICAL IMPLICATIONS: This laboratory evaluation shows that amalgam separators and the filtration devices removed at least 97.05 percent of the amalgam in samples with particle-size distribution as specified in ISO Standard 11,143.

The effect of disinfectants and line cleaners on the release of mercury from amalgam.

BACKGROUND: Dental practices use disinfectants or line cleaners to flush dental unit wastewater lines to minimize odor generation, remove solid waste particles and remove biofilms in dental unit water lines (DUWLs). METHODS: The authors evaluated 47 disinfectants or line cleaners for their potential to release mercury from amalgam waste. They prepared each product concentration according to the manufacturer's recommendations and gently agitated it along with one amalgam specimen for 24 hours. They filtered the combined decanted liquid and rinse and analyzed it for mercury using modified U.S. Environmental Protection Agency method 245.1. RESULTS: Six preparations released significantly more mercury from amalgam (about 17 to 340 times) than did the deionized water control (P < .001). The amount of mercury released by the other disinfectants/line cleaners was not statistically different from that released by the control. The pH values of all preparations ranged from 1.76 to 12.35. CONCLUSION AND CLINICAL IMPLICATIONS: This study and other published reports have demonstrated that preparations containing chlorine release more mercury from amalgam than did some other products and the deionized water control. As a result, the use of these products is not recommended for treating dental office wastewater lines or DUWLs.

Light-emitting diode curing light irradiance and polymerization of resin-based composite.

BACKGROUND: Light-emitting diode (LED) curing lights are becoming popular; however, questions about their efficiency remain. The authors performed a comprehensive analysis of the properties of resin-based composites cured with LED lights. METHODS: The authors evaluated seven LED lights and one quartz-tungsten-halogen light (control). They measured intensity, depth of cure (DOC), degree of conversion (DC), hardness and temperature rise. They used three shades of a hybrid resin-based composite and a microfill composite, as well as one shade of another hybrid composite. RESULTS: Two LED lights required additional cure time to reach a DOC similar to that of the control light. DC at the top of the samples was independent of the light used. At 2.0 millimeters, the DC for several LED lights was significantly lower than that for the control light and was correlated strongly to the light's intensity. The bottom-to-top ratio for hardness of resin-based composites cured by all but one light was greater than 0.80. All LED lights except one had smaller temperature rise than did the control light. CONCLUSIONS: Six of the seven LED curing lights performed similarly to a quartz-tungsten-halogen curing light in curing resin-based composites. Clinical Implications. While LED curing lights and a quartz-tungsten-halogen light could cure resin-based composites, some resin-based composites cured with LED lights may require additional curing time or smaller increments of thickness.

Amalgam waste management.

Dental amalgam has been extensively used as a tooth filling material for many decades and has beyond doubt saved millions of teeth that otherwise would have needed to be extracted. The release of amalgam particles into dental office wastewater is a matter of particular concern as amalgam particles could then be discharged into the environment. Amalgam waste discharges contribute to mercury in the environment through direct wastewater discharge, incineration, land-filling and sewage sludge incineration, although the discharge from dentistry is probably responsible for less than 1% of the total mercury discharged annually into the environment as a result of human activities. Nevertheless, dentists, by being producers of amalgam waste, have a responsibility and a duty of care for the proper management of this waste within their practices. Appropriate measures should be taken to minimise the amount of waste where possible or take action to ensure that all generated waste is disposed of in accordance with environmental legislation.

Erosion of composite resins.

The surface degradation of composite resins caused by accelerated aging was studied. Accelerated aging for 900 hours caused erosion of the resin matrices and exposure of filler particles. Differences in surface profiles after aging suggest that the materials eroded at different rates. Accelerated aging may model erosive wear of composites.

Color stability and aging of plastic veneering materials.

The color stability and aging characteristics of commercial plastic veneering materials were studied in vitro by an accelerated aging method. Values of luminous reflectance, dominant wavelength, and excitation purity at baseline were similar to values reported for composite restorative materials. The veneering materials were more opaque than composites. After aging for 900 h, small changes in color were observed instrumentally, but were difficult to detect visually. Weight loss of some the veneering materials after aging was greater than that anticipated from solubility in water alone.

In vitro accelerated aging of composites and a sealant.

The in vitro accelerated aging of conventional and microfilled composite restorative materials and a sealant was studied. Volume loss/surface area ranged from 2.0 x 10(-3) mm3/mm2 for I to 7.3 x 10(-3) mm3/mm2 for SF after 900 h of aging. Surface morphology of the conventional composites was characterized by crazing and exposure of filler particles. The surfaces of the microfilled composites also showed crazing. The surface morphology of the sealant appeared unchanged. Comparisons of infrared ATR spectra between zero and 900 h of aging showed that slight chemical changes occurred at the surface of AR but not SF.

Color stability of new composite restorative materials under accelerated aging.

The color stability of seven commercial composite restorative materials under conditions of accelerated aging was evaluated by reflection spectrophotometry at baseline and 300, 600, and 900 h. During early aging the composites generally became darker, more chromatic, and more opaque. Changes in color of the conventional composites during aging were influenced by erosion of the resin matrices and exposure of filler particles. Color stability of the microfilled composites under the in vitro conditions tested was better than that of the conventional composites and did not appear to be influenced as much by erosion.

Translucency of dental porcelains.

The translucency of comparable shades of five dental porcelains was determined. Both direct transmittance and total transmittance were measured at wavelengths of 400-700 nm. For 1 mm of porcelain, the values for direct transmittance were low and averaged 0.13 percent, whereas the values for total transmittance averaged 26.8 percent. Transmittance increased with increasing incident wavelength. These results indicated a high degree of light scattering.

In vitro wear of microfilled and visible light-cured composites.

Wear of microfilled composites, a visible light-cured composite, and a conventional composite were characterized by two-body abrasion and single-pass sliding. There were differences in abrasion rates among the materials. Tangential forces, wear track widths, and surface failure modes were different among materials. Wear characteristics are combinations of these properties.

Penetrativity of sealants: I.

Penetration coefficients of sealants were measured. It was found that the time required for a sealant to penetrate a specific distance is highly dependent on the penetration coefficient of the sealant.

Frictional behavior and surface failure of acrylic denture teeth.

The water characteristics of acrylic denture teeth were investigated under single- and double-pass sliding. The response of acrylic teeth to sliding was that of a relatively ductile material. The wear characteristics were affected similarly by environments of water and saliva. The "enamel" surfaces showed more resistance to penetration and were less susceptible to surface damage than the "dentin" surfaces. The effect of the second pass was to increase track width and cause a more severe mode of surface failure.

Alternative interpretations of water sorption values of composite resins.

Water sorption values for direct filling resins and an unfilled resin were much more similar at 30 days when expressed as mg/g organic matrix than as mg/cm2 or weight percent. This interpretation is indicative of the water sorption characteristics of resin matrices. The values are even more indicative when solubility or leaching is taken into consideration. With the specimen sizes used in this study, the effect of the kinetics of water sorption could be minimized by using values obtained after immersion in water for 30 days.

Effects of backing reflectance and mold size on polymerization of photo-activated composite resin.

The in vitro depth of cure of a visible-light-activated microfilled composite, as influenced by backing reflectance and mold size, was investigated using microhardness measurements. More extensive polymerization was obtained with higher values of backing reflectance. Mold size larger than the cross-sectional area of the photo-activating beam also increased the degree of polymerization. Backing reflectance and mold size are influential factors and need to be defined in depth-of-cure evaluations if in vitro measurements are to be valid predictors of clinical performance.

Translucency of human dental enamel.

Translucency of human dental enamel was determined by total transmittance of wavelengths from 400 to 700 nm. The transmission coefficient at 525 nm was 0.481 mm-1. Total transmission of light through human dental enamel increased with increasing wavelength. Human tooth enamel is more translucent at higher wavelengths. The translucency of wet human enamel and enamel after dehydration was also measured by total transmittance. The transmission coefficient at 525 nm decreased from 0.482 to 0.313 mm-1 after dehydration and was reversed on rehydration. The decrease in translucency occurred as a result of the replacement of water around the enamel prisms by air during dehydration.

Adsorption of Streptococcus mutans on chemically treated hydroxyapatite.

Adsorption of Streptococcus mutans on hydroxyapatite and chemically treated hydroxyapatite was studied. Zeta potentials of the surfaces were measured. Chemically treated hydroxyapatite gave higher zeta potentials and lower S mutans adsorption.