Influence of bismuth oxide concentration on the pH level and biocompatibility of white Portland cement

Objectives

To investigate if there is a relation between the increase of bismuth oxide and the decrease of pH levels and an intensification of toxicity in the Portland cement.

Material and Methods

White Portland cement (WPC) was mixed with 0, 15, 20, 30 and 50% bismuth oxide, in weight. For the pH level test, polyethylene tubes were filled with the cements and immersed in Milli-Q water for 15, 30 and 60 days. After each period, the increase of the pH level was assessed. For the biocompatibility, two polyethylene tubes filled with the cements were implanted in ninety albino rats (n=6). The analysis of the intensity of the inflammatory infiltrate was performed after 15, 30 and 60 days. The statistical analysis was performed using the Kruskal-Wallis, Dunn and Friedman tests for the pH level and the Kruskal-Wallis and Dunn tests for the biological analysis (p<0.05).

Results

The results showed an increase of the pH level after 15 days, followed by a slight increase after 30 days and a decrease after 60 days. There were no significant statistical differences among the groups (p>0.05). For the inflammatory infiltrates, no significant statistical differences were found among the groups in each period (p>0.05). The 15% WPC showed a significant decrease of the inflammatory infiltrate from 15 to 30 and 60 days (p<0.05).

Conclusions

The addition of bismuth oxide into Portland cement did not affect the pH level and the biological response. The concentration of 15% of bismuth oxide resulted in significant reduction in inflammatory response in comparison with the other concentrations evaluated.     

Evaluation of fluoride release from experimental TiF4 and NaF varnishes in vitro

Fluoride varnishes play an important role in the prevention of dental caries, promoting the inhibition of demineralization and the increase of remineralization.

Objective

This study aimed to analyze the amount of fluoride released into water and artificial saliva from experimental TiF₄ and NaF varnishes, with different concentrations, for 12 h.

Material and Methods

Fluoride varnishes were applied on acrylic blocks and then immersed in 10 ml of deionized water and artificial saliva in polystyrene bottles. The acrylic blocks were divided in seven groups (n=10): 1.55% TiF₄ varnish (0.95% F, pH 1.0); 3.10% TiF₄ varnish (1.90% F, pH 1.0); 3.10% and 4% TiF₄ varnish (2.45% F, pH 1.0); 2.10% NaF varnish (0.95% F, pH 5.0); 4.20% NaF varnish (1.90% F, pH 5.0); 5.42% NaF varnish (2.45% F, pH 5.0) and control (no treatment, n=5). The fluoride release was analyzed after 1/2, 1, 3, 6, 9 and 12 h of exposure. The analysis was performed using an ion-specific electrode coupled to a potentiometer. Two-way ANOVA and Bonferroni''s test were applied for the statistical analysis (p<0.05).

Results

TiF₄ varnishes released larger amounts of fluoride than NaF varnishes during the first 1/2 h, regardless of their concentration; 4% TiF₄ varnish released more fluoride than NaF varnishes for the first 6 h. The peak of fluoride release occurred at 3 h. There was a better dose-response relationship among the varnishes exposed to water than to artificial saliva.

Conclusions

The 3.10% and 4% TiF₄ -based varnishes have greater ability to release fluoride into water and artificial saliva compared to NaF varnish; however, more studies must be conducted to elucidate the mechanism of action of TiF₄ varnish on tooth surface.     

Erosive cola-based drinks affect the bonding to enamel surface: an in vitro study

Objective

This study aimed to assess the impact of in vitro erosion provoked by different cola-based drinks (Coke types), associated or not with toothbrushing, to bonding to enamel.

Material and Methods

Fifty-six bovine enamel specimens were prepared and randomly assigned into seven groups (N=8): C- Control (neither eroded nor abraded), ERO-RC: 3x/1-minute immersion in Regular Coke (RC), ERO-LC: 3x/1-minute immersion in Light Coke (LC), ERO-ZC: 3x/1-minute immersion in Zero Coke (ZC) and three other eroded groups, subsequently abraded for 1-minute toothbrushing (EROAB-RC, EROAB-LC and EROAB-ZC, respectively). After challenges, they were stored overnight in artificial saliva for a total of 24 hours and restored with Adper Single Bond 2/Filtek Z350. Buildup coronal surfaces were cut in 1 mm² -specimens and subjected to a microtensile test. Data were statistically analyzed by two-way ANOVA/Bonferroni tests (α=0.05). Failure modes were assessed by optical microscopy (X40). The interface of the restorations were observed using Confocal Laser Scanning Microscopy (CLSM).

Results

All tested cola-based drinks significantly reduced the bond strength, which was also observed in the analyses of interfaces. Toothbrushing did not have any impact on the bond strength. CLSM showed that except for Zero Coke, all eroded specimens resulted in irregular hybrid layer formation.

Conclusions

All cola-based drinks reduced the bond strength. Different patterns of hybrid layers were obtained revealing their impact, except for ZC.     

Biochemical study and in vitro insect immune suppression by a trypsin‐like secreted protease from the nematode Steinernema carpocapsae

A trypsin‐like serine protease was purified by gel filtration and anion‐exchange chromatography from the excretory‐secretory products of parasitic phase Steinernema carpocapsae. The purified protease exhibited a molecular mass of about 29 kDa by SDS–PAGE and displayed a pI of 6·3. This protease exhibited high activity with trypsin‐specific substrate N‐Ben‐Phe‐Val‐Arg‐p‐nitroanilide and was highly sensitive to aprotinin and benzamidine. The purified trypsin protease digested the chromogenic substrate N‐Ben‐Phe‐Val‐Arg‐p‐nitroanilide with K_m, V_max and k_cat values of 594·2 μm , 0·496 μm /min and 22·8/s, respectively. The optimal pH and temperature for protease activity were 9 and 30°C, respectively. Internal amino acid sequencing yielded 150 amino acids and these were homologous to other trypsin sequences. In vitro investigation was carried out to monitor prophenoloxidase suppression in Galleria mellonella by the purified protease; about 38·9–52·6% suppression of prophenoloxidase was observed. The purified protease affected insect haemocyte spreading, causing cells to become spherical or round. Protease‐treated actin filaments were highly disorganized in haemocytes. In vitro, G. mellonella haemocytes recognized infective juveniles of Heterorhabditis bacteriophora; however, S. carpocapsae and Steinernema glaseri were not recognized. We provide experimental evidence that the purified trypsin has the potential to alter host haemocytes, actin filaments and to inhibit host haemolymph melanization.     

Contact allergy in relation to hand eczema and atopic diseases in north Norwegian schoolchildren

Dotterud LK, Falk ES. Contact allergy in relation to hand eczema and atopic diseases in north Norwegian schoolchildren. Acta Psediatr 1995;84:402–6. Stockholm. ISSN 0803–5253
Patch testing was carried out in 424 schoolchildren (223M, 201F), aged 7–12 years, in northern Norway. In 99 (23.3%) of these children, one or more allergic patch test reactions were demonstrated; 30 children reacted to two and 6 to three or more substances; 53 irritant reactions were recorded in 33 (7.8%) of those tested. From a total of 144 positive tests, the most common allergen was nickel (14.9%), followed by cobalt (5.7%), kathon CG (5.2%), lanolin (1.7%) and neomycin (1.4%). Both allergic and irritant reactions were found twice as frequently in girls as in boys. Positive patch tests were significantly more frequent in atopic (28.8%) than in non–atopic (17.9%) children, being most pronounced in atopic girls (37.4%). Hand eczema was reported to have occurred or to be present in 6.5% of cases. Twenty–nine of 36 children reporting hand eczema participated in the clinical examination. Altogether 15 (3.5%) children had hand eczema at the time of the clinical examination but 12 of these children had no previous history of hand eczema. In 14 of these 15 subjects, the eczema was localized to the back of the hands, with 13 having atopic dermatitis. In 4 of these 15 children, an allergic patch test reaction was found; however, in only 2 of these 4 was the test considered to be clinically relevant for the diagnosis allergic hand eczema. In conclusion, irritant hand eczema may occur in early childhood and is most prevalent in children with atopic dermatitis     

Myocardial perfusion imaging with technetium-99m sestamibi SPECT in the evaluation of coronary artery disease

Technetium-99m hexakis-2-methoxy-isobutyl-isonitrile(^99mTc sestamibi) has been used for myocardial perfusion imaging in the evaluation of coronary artery disease (CAD) since 1990. The experience of its use in an Asian population with and without previous myocardial infarction (Ml), diabetes mellitus (DM), hypertension (HPT) and collateral circulation (COL) is reported. One hundred and thirty-nine patients who underwent treadmill exercise testing with ^99mTc sestamibi single photon emission computed tomography (SPECT) and coronary angiogram were studied. The overall sensitivity for the detection of CAD was 91.0% and specificity was 64.7%. For patients without previous myocardial infarction, the sensitivity was 83.8% and specificity was 83.3%. Patients with COL had a higher sensitivity while those with HPT had a lower specificity. Sensitivity was higher in patients with multi-vessel disease (MVD) than single vessel disease (SVD). The overall detection for individual artery stenosis was 74.1% with a specificity of 73.1 %. Amongst the three major coronary arteries, sensitivity was highest for the right coronary artery and specificity was highest for the left circumflex artery. Specificity was higher in patients without MI or COL. We found that the agreement between ^99mTc sestamibi SPECT and coronary angiogram for the extent of CAD was only 52.5%. The concordance rate was higher for patients with MVD than SVD. It is concluded that ^99mTc sestamibi SPECT is a sensitive and specific test for the detection of CAD and localization of disease to individual coronary arteries in our patients with some differences in the subgroups. Agreement between coronary angiogram and ^99mTc sestamibi for the extent of coronary artery disease was also satisfactory.     

One-year audit of admissions to the Intensive Care Unit of the Queen Elizabeth Central Hospital,Blantyre

The intensive care unit at Queen Elizabeth Central Hospital (QECH) has 4 beds and offers level 2 care. A retrospective audit of all admissions to the unit during 2002 was carried out. There were a total of 339 admissions giving a bed occupancy rate of 82 %. Surgical patients made up 81 % of admissions. 45% of all admissions were ventilated. Overall mortality was 38%. Ventilated patients had a mortality of 71% compared with 10% for non-ventilated. Data are also presented for mortality within the surgical and paediatric surgical admissions.     

Mediastinal and hilar fibrosis

A case is described of mediastinal and hilar fibrosis in a woman aged 22 years. The fibrotic mass compressed the lobar arteries as well as the veins of various lobes of both lungs. These large vessels as well as numerous smaller arteries and veins were to a large extent obstructed by organized thrombi. It seems likely that 3 years after the beginning of symptoms the fibrosing process was still active. The case provides some support for an immunopathological aetiology of this condition.