Flexibility and torsional behaviour of rotary nickel-titanium PathFile, RaCe ISO 10, Scout RaCe and stainless steel K-File hand instruments.

AIM: To assess and compare the flexibility and torsional resistance of PathFile, RaCe ISO 10 and Scout RaCe instruments in relation to stainless steel K-File hand instruments. METHODOLOGY: Rotary PathFile (sizes 13, 16 and 19; .02 taper), Race ISO 10 (size 10; 0.02, 0.04 and 0.06 tapers), Scout RaCe (sizes 10, 15 and 20; 0.02 taper) and hand K-File (sizes 10, 15 and 20; 0.02 taper) instruments were evaluated. Alloy chemical composition, phases present and transformation temperatures were determined for the NiTi instruments. For all instruments, diameters at each millimetre from the tip as well as cross-sectional areas at 3 mm from the tip were measured based on ANSI/ADA Specification No. 101 using image analysis software. Resistance to bending and torsional resistance were determined according to specification ISO 3630-1. Vickers microhardness measurements were also taken in all instruments to assess their strength. Data were analysed using analysis of variance (α = 0.05). RESULTS: The alloys used in the manufacture of the three types of NiTi instruments had approximately the same chemical composition, but the PathFile instruments had a higher Af transformation temperature and contained a small amount of B19' martensite. All instruments had diameter values within the standard tolerance. The bending and torsional resistance values were significantly increased relative to the instrument diameter and cross-sectional area. CONCLUSIONS: PathFile instruments were the most flexible and the least torque resistant, whilst the stainless steel instruments were the least flexible although they were more torque resistant than the NiTi instruments.

Pulpal Temperature Variances During Step-by-step Adhesive Restorative Procedure Using Three Different High-irradiance Light-curing Units.

The rise in temperature in pulp tissues is related not only to heat transfer by high-irradiance light-curing units (LCUs), but also to restorative procedures. This research aimed to compare the rise in pulp temperature (PT) induced by three LCUs at each restorative step while considering the influence of resin composite shade and thickness. To accomplish this, the investigators used a proposed experimental model replicating pulp fluid circulation with a controlled, simulated intraoral temperature in bovine incisors. The recorded external and internal PT ranged from 36.7°C to 37.1°C and 32.7°C to 33.0°C, respectively. A significant decrease of internal temperature was recorded during class V preparation, followed by a progressive and representative rise of temperature in the subsequent restorative steps. The temperature was significantly higher during light curing of the adhesive system using Valo compared to light curing using Elipar and Radii Cal. However, none of the analyzed devices produced a temperature that exceeded the pulp tolerance limit (a temperature increase over 5.5°C). The paired test showed no significant difference in pulp temperature associated with the thickness of the increment of resin composite. However, shade was found to have more influence on the amount of energy absorbed by pulp tissue-A1 samples showed significantly higher temperature variation compared to samples using the A4 shade of resin composite. To conclude, the microcirculation and the performance of procedures under constant air-water flux dissipate the heat absorbed by the pulp. Additionally, the data suggest that all three LCUs analyzed can be safely used in clinical procedures, and that the resin composite shade may influence the amount of irradiance delivered to the tooth surface and represents a significant factor in pulp temperature variance.

Physical and mechanical properties of twisted or ground nickel-titanium instruments.

AIM: To compare the flexibility, torsional resistance and structural and dimensional characteristics of instruments produced by twisting with those of a geometrically similar nickel-titanium (NiTi) system produced by a grinding process. METHODOLOGY: The mean diameters along the flute and the pitch length of size 25, .04 taper, size 25, .06 taper, and size 25, .08 taper Twisted File (TF) (SybronEndo, Orange, CA, USA), and size 25, .04 taper, and size 25, .06 taper RaCe instruments (FKG, La Chaux-de-Fonds, Switzerland) (n = 10 each) were measured according to ANSI/ADA specification No. 101. Two pairs of instruments were found to have similar diameters at 3 mm from the tip: TF size 25, .06 taper and RaCe size 25, .04 taper, and TF size 25, .08 taper and RaCe size 25, .06 taper. The cross-sectional areas at 3 mm from the tip were determined. These instruments were then submitted to energy-dispersive X-ray spectroscopy, X-ray diffraction, differential scanning calorimetry (DSC), and Vickers microhardness measurements. Bending moment at 45° and maximum torque at fracture were measured (n = 10) according to specification ISO 3630-1. Data were analysed using analysis of variance (α = 0.05). RESULTS: The two types of instruments had approximately the same chemical composition, phase constitution, and austenite finishing temperatures. TF instruments had significantly (P ≤ 0.001) lower Vickers microhardness values and were more flexible than RaCe instruments (P = 0.016), but had similar (TF size 25, .08 taper and RaCe size 25, .06 taper, P = 0.916) or significantly higher (TF size 25, .06 taper and RaCe size 25, .04 taper, P ≤ 0.001) torsional resistance. CONCLUSIONS: Comparison of TF and RaCe instruments of similar measured dimensions revealed that the different manufacturing methods employed for producing these instruments gave rise to different mechanical behaviours.

Torsional behaviour of rotary NiTi ProTaper Universal instruments after multiple clinical use.

AIM: To assess the influence of multiple clinical uses on the torsional behaviour of ProTaper Universal rotary NiTi instruments. METHODOLOGY: Root canal treatments were performed on patients using the ProTaper Universal rotary system to prepare canals. Ten sets of instruments were used by an experienced endodontist, each set being used in five molar teeth. After clinical use, S1, S2, F1 and F2 instruments were analysed for damage by optical and scanning electron microscopy. The used sets, along with a control group of 10 sets of new instruments, were then torsion tested based on the ISO 3630-1 specification. Data obtained were subjected to a one-way analysis of variance (anova) with alpha = 0.05. RESULTS: The use of the ProTaper Universal rotary instruments by an experienced endodontist allowed for the cleaning and shaping of the root canal system of five molar teeth without fracture. The maximum torque for instruments S2, F1 and F2, and the angular deflection at fracture for instruments S2 and F1 were significantly lower following clinical use. The largest decrease in maximum torque was 18.6% (P = 0.014) for S2 instruments. The same maximum percent decrease was found for angular deflection at fracture for F1 instruments (P = 0.009). CONCLUSIONS: Torsional resistance and angular deflection of used instruments, as compared to that of new instruments, were reduced following clinical use.

Novel combretastatin analogues effective against murine solid tumors: design and structure-activity relationships.

A series of combretastatin A-4 (CA-4) analogues were synthesized, and their cytotoxic effects against murine Colon 26 adenocarcinoma and inhibitory activity on tubulin polymerization were evaluated. Since CA-4 has limited aqueous solubility, the target compounds were designed to improve solubility by introduction of a nitrogen-containing group. Among the compounds synthesized, those with an amino moiety in place of the phenolic OH of CA-4 showed potent antitubulin activity and cytotoxicity against murine Colon 26 adenocarcinoma in vitro. Some of the compounds which were potent in vitro were evaluated in the murine tumor model Colon 26 in vivo. Among these, 13bHCl, 21aHCl, and 21bHCl showed significant antitumor activity in the animal model, while CA-4 was ineffective. 13bHCl and 21aHCl were further evaluated in two murine tumor models (Colon 38 and 3LL) and human xenografts HCT-15. These compounds showed potent antitumor activity comparable or superior to that of CDDP. The structure-activity relationships of this series of compounds are also discussed.

[Anti-leukotoxin antibodies against Actinobacillus actinomycetemcomitans in serum and saliva samples from patients with localized juvenile periodontitis]. / Anticorpos antileucotoxina contra Actinobacillus actinomycetemcomitans em amostras de soro e saliva de pacientes com periodontite juvenil localizada.

The leukotoxin produced by Actinobacillus actinomycetemcomitans is considered the major virulence factor with potential to cause damage to the host defenses. The present work analyzed the serumal and salivary levels of antibodies against the leukotoxin produced by A. Actinomycetemcomitans, in patients with Localized Juvenile Periodontitis (LJP) and in healthy controls. Additionally, analysis of the immune complex (IC) was carried out in saliva samples. The classic ELISA method, with leukotoxin obtained through Sephadex G-200 gel filtration, and the capture ELISA method, using rabbit anti-A. Actinomycetemcomitans (leukotoxic, FDC Y4, IgG) adsorbed with a non-leukotoxic strain of A. actinomycetemcomitans, were used. The results obtained demonstrated significantly higher serumal levels of IgG in patients with LJP, when they were compared with the healthy controls, both for the classic and capture ELISA methods (p < 0.05). However, no significant differences were observed between the salivary levels of IgG, SIgA and IC in the examined individuals. These results suggest that even though A. actinomycetemcomitans presents virulence factors that affect the immune response, there is immune response to leukotoxin in LJP patients. This increase of IgG in the blood stream might contribute to host defense, limiting the lesion to the periodontal regions already colonized by A. actinomycetemcomitans.

[Polychlorinated dibenzofurans (PCDFs) in the subcutaneous adipose tissue of yusho patients and normal controls].

Polychlorinated dibenzofurans (PCDFs) are well known to be the toxic chemicals in both animal experiments and human studies. It is, therefore, important to determine the level of PCDFs still retained in patients for understanding relationship between the concentration of PCDFs and present symptoms of the disease. In this study, the abdominal subcutaneous adipose tissue of 18 yusho patients and those of 11 normal controls who were all of volunteers were collected, and their levels were determined by high resolution gas chromatography/high resolution mass spectrometry. Results obtained were as follows: The principal compounds detected in the adipose tissue of yusho patients were 2,3,4,7,8-pentachlorodibenzofuran (PenCDF), 1,2,3,4,7,8- and 1,2,3,6,7,8-hexachlorodibenzofuran (HCDF). The concentration of the compounds in 7 patients, wearing typical symptoms, from 160 to 3,000 ppt for 2,3,4,7,8-PenCDF, from 51 to 1,000 ppt for 1,2,3,4,7,8-HCDF, and from 16 to 220 ppt for 1,2,3,6,7,8-HCDF. In normal controls, 2,3,4,7,8-PenCDF was detected only in five samples at the low level of from 16 to 38 ppt. On an average, PCDF levels in in the typical 7 yusho patients and 11 normal controls were 1,900 ppt and 16 ppt, respectively. On the basis of the results, the concentrations of PCDF congeners in the adipose tissues of the typical 7 patients was 100 times higher than that of the normal controls. Hence, we consider that the present levels of PCDFs in the patients probably play an important role for the symptoms of the yusho.

[Therapeutic trial for promotion of fecal excretion of PCDFs and PCBs by the administration of cholestyramine in Yusho patients].

Any effective therapy for elimination of causal agents remaining in Yusho patients was not found until now. To know the profile of fecal excretion of polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs), the amounts of PCDFs and PCBs in the stool of six Yusho patients with the typical symptoms were determined. The stool samples of Yusho patients were collected in 1989. PCDFs, i.e., 2,3,7,8-tetrachlorodibenzofuran (TCDF), 2,3,4,7,8-pentachlorodibenzofuran (PnCDF), 1,2,3,4,7,8- and 1,2,3,6,7,8-hexachlorodibenzofurans (HxCDFs), 1,2,3,4,6,7,8-heptachlorodibenzofuran (HpCDF) and octachlorodibenzofuran (OCDF) were detected in all of the samples. PCDFs found in the stool samples were mostly PnCDF and HxCDFs. Of PCDFs detected, PnCDF and HxCDFs contributed to 42 +/- 4.7% and 43 +/- 5.5% as mean +/- SE, respectively. The fecal excretion of PnCDF and HxCDFs in Yusho patients was 720 +/- 490 pg/day and 790 +/- 620 pg/day as mean +/- SE, respectively. On the other hand, the fecal excretion of PnCDF and HxCDFs in normal controls was 32 +/- 13 pg/day and 47 +/- 5.2 pg/day as mean +/- SE, respectively. The fecal excretion of PnCDF and HxCDFs in Yusho patients was about 23 times and 17 times each higher than that in normal controls. The fecal excretion of PCBs in Yusho patients and normal controls was 400 +/- 430 ng/day and 150 +/- 39 ng/day, respectively, as mean +/- SE. In order to promote the excretion of these toxic chemicals in the stool of Yusho patients, the patients were continuously administered with cholestyramine, an anion exchange resin, at a dose of 4 g, 3 times a day, for 6 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical trial of a combination of rice bran fiber and cholestyramine for promotion of fecal excretion of retained polychlorinated dibenzofuran and polychlorinated biphenyl in Yu-Cheng patients.

A clinical trial using the combination of rice bran fiber (RBF) and cholestyramine (CHO) was carried out on Yu-Cheng patients in 1993-1994. By the analysis of blood and stool samples collected from the patients before and after (or during in the case of stool), it was verified that the administration of RBF and CHO is effective for excretion of polychlorinated biphenyl (PCB) (p < 0.05) and polychlorinated dibenzofuran (PCDF), especially 2, 3, 4, 7, 8-pentachlorodibenzofuran (p < 0.05). However, the degree of effectiveness varied upon individual patients from 60 to 160% for 2, 3, 4, 7, 8-pentachlorodibenzofuran, from 30 to 110% for 1, 2, 3, 4, 7, 8-hexachlorodibenzofuran and from 50 to 190% for PCB, respectively.

[Therapeutic trials for promotion of faecal excretion of PCDFs by the administration of rice bran fiber and cholestyramine in Yusho patients].

It is well-known that Yusho disease was caused by polychlorinated dibenzofurans (PCDFs), and that 2, 3, 4, 7, 8-Pentachlorodibenzofuran (PnCDF), 1, 2, 3, 4, 7, 8- and 1, 2, 3, 6, 7, 8-Hexachlorodibenzofurans (HxCDFs) still retain in the patient bodies. As patients usually suffer from various chronic syndrome, an effective treatment is extremely needed. In order to assess the rice bran fiber (RBF) and cholestyramine on stimulating faecal excretion of PCDFs, two clinical trials were carried out in 1990 and 1991. In the first trial in 1990, 10 g of RBF (dietary fiber content was 50%) and 4 g of cholestyramine were administered to four Yusho patients three times a day for a week. The stool from patients were collected a week before and during the administration. These were pooled respectively, and then two samples for measurement. In the second trial in 1991, 10 g of dietary fiber rich RBF (refined-RBF, dietary fiber content was 85%) and 4 g of cholestyramine were administered to four Yusho patients three times a day for two weeks. In this trial, three stool samples were obtained from each patient, ie., a week before administration, and first and second week during administration. Level of PCDFs was determined by high resorption GC/MS and the following results were obtained. 1) In the first trial (1990) the faecal excretion of PnCDF and HxCDFs increased at the rates of 42-88% and 7-47%, respectively, in three out of four patients.(ABSTRACT TRUNCATED AT 250 WORDS)

An in vitro evaluation of four materials as barriers to coronal microleakage in root-filled teeth.

AIM: To assess the ability of IRM, Coltosol, Vidrion R and Scotch Bond to seal the pulp chamber following root-canal treatment. METHODOLOGY: Root-canal treatment was completed on 100 extracted human mandibular molars. The teeth were divided into five groups of 20 teeth each, one group for each barrier material and one control group without barrier material. Two millimetres of the restorative material was placed on the pulp chamber floor. The teeth were thermocycled and evaluated for microleakage using India ink. Specimens were cleared and measurements made to the maximum point of dye penetration. The mean dye penetration for each group was compared by the Kruskal-Wallis test. RESULTS: All groups showed dye penetration. Coltosol and IRM sealed significantly better than the other groups, preventing the coronal leakage in 84% and 75% of the specimens, respectively. Scotch Bond exhibited the highest leakage (54% of specimens with dye penetration), which did not differ significantly from the positive control group (62% with dye penetration). CONCLUSIONS: None of the materials were able to prevent microleakage in all specimens. Vidrion R and Scotch Bond demonstrated the poorest results when used as barriers to coronal microleakage, whilst IRM and Coltosol were significantly better in preventing microleakage.