Canine visceral leishmaniasis: Performance of a rapid diagnostic test (Kalazar Detect (TM)) in dogs with and without signs of the disease

Current visceral leishmaniasis (VL) control programs in Brazil include the infected dog elimination but, despite this strategy, the incidence of human VL is still increasing. One of the reasons is the long delay between sample collection, analysis, control implementation and the low sensitivity of diagnostic tests. Due to the high prevalence of asymptomatic dogs, the diagnosis of these animals is important considering their vector infection capacity. Hence, a rapid and accurate diagnosis of canine visceral leishmaniasis is essential for an efficient surveillance program. In this study we evaluated the performance of rK39 antigen in an immunochromatographic format to detect symptomatic and asymptomatic Leishmania chagasi infection in dogs and compared the results with those using a crude antigen ELISA. The sensitivity of rK39 dipstick and ELISA were 83% vs. 95%, respectively, while the specificity was both 100%. Our results also demonstrated that the dipstick test was able to detect infected dogs presenting different clinical forms. (C) 2008 Elsevier B.V. All rights reserved.

EFFECT OF METAL PRIMERS ON MICROTENSILE BOND STRENGTH BETWEEN ZIRCONIA AND RESIN CEMENTS

Statement of problem. There are no established clinical procedures for bonding zirconia to tooth structure using resin cements. Purpose. The purpose of this study was to evaluate the influence of metal primers, resin cements, and aging on bonding to zirconia. Material and methods. Zirconia was treated with commercial primers developed for bonding to metal alloys (Metaltite, Metal Primer II, Alloy Primer or Totalbond). Non-primed specimens were considered as controls. One-hundred disk-shaped specimens (19 x 4 mm) were cemented to composite resin substrates using Panavia or RelyX Unicem (n=5). Microtensile bond strength specimens were tested after 48 hours and 5 months (150 days), and failure modes were classified as type 1 (between ceramic/cement), 2 (between composite resin/cement) or 3 (mixed). Data were analyzed by 3-way ANOVA and Multiple Comparison Tukey test (alpha=.05). Results. The interactions primer/luting system (P=.016) and luting system/storage time (P=.004) were statistically significant. The use of Alloy Primer significantly improved the bond strength of RelyX Unicem (P<.001), while for Panavia, none of the primers increased the bond strength compared to the control group. At 48 hours, Panavia had statistically higher bond strength (P=.004) than Unicem (13.9 +/- 4.4MPa and 10.2 +/- 6.6MPa, respectively). However, both luting systems presented decreasing, statistically similar; values after aging (Panavia: 3.6 +/- 2.2MPa; Unicem: 6.1 +/- 5.3MPa). At 48 hours, Alloy Primer/Unicem had the lowest incidence of type 1 failure (8%). After aging, all the groups showed a predominance of type 1 failures. Conclusions. The use of Alloy Primer improved bond strength between RelyX Unicem and zirconia. Though the initial values obtained with Panavia were significantly higher than RelyX Unicem, after aging, both luting agents presented statistically similar performances. (J Prosthet Dent 2011;105:296-303)

Direct comparison of the bond strength results of the different test methods: A critical literature review

Objective. The goal of this paper is to undertake a literature search collecting all dentin bond strength data obtained for six adhesives with four tests ( shear, microshear, tensile and microtensile) and to critically analyze the results with respect to average bond strength, coefficient of variation, mode of failure and product ranking. Method. A PubMed search was carried out for the years between 1998 and 2009 identifying publications on bond strength measurements of resin composite to dentin using four tests: shear, tensile, microshear and microtensile. The six adhesive resins were selected covering three step systems ( OptiBond FL, Scotch Bond Multi-Purpose Plus), two-step (Prime & Bond NT, Single Bond, Clear. l SE Bond) and one step (Adper Prompt L Pop). Results. Pooling results from 147 references showed an ongoing high scatter in the bond strength data regardless which adhesive and which bond test was used. Coefficients of variation remained high (20-50%) even with the microbond test. The reported modes of failure for all tests still included high number of cohesive failures. The ranking seemed to be dependant on the test used. Significance. The scatter in dentin bond strength data remains regardless which test is used confirming Finite Element Analysis predicting non-uniform stress distributions due to a number of geometrical, loading, material properties and specimens preparation variables. This reopens the question whether, an interfacial fracture mechanics approach to analyze the dentin - adhesive bond is not more appropriate for obtaining better agreement among dentin bond related papers. (C) 2009 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effect of Test Environment and Microstructure on the Flexural Strength of Dental Porcelains

Purpose: The objective of this study was to verify the influence of test environment on the flexural strength of dental porcelains with distinct microstructures. Material and Methods: Disk-shaped specimens from three dental porcelains with distinct leucite content (VM: zero; CE: 12; NS: 22 vol%) were manufactured and tested for biaxial flexural strength in air and immersed in artificial saliva. The results were analyzed by means of two-way ANOVA and Tukey`s test (alpha = 0.05). Results: The flexural strength (MPa) obtained for ambient air and artificial saliva environments, respectively, were: 110.0 +/- 16.0 and 81.5 +/- 10.8 for VM; 51.9 +/- 4.0 and 42.0 +/- 4.7 for CE; 72.0 +/- 11.5 and 63.6 +/- 5.8 for NS. A numerical decrease in the mean flexural strength was observed for all groups when specimens were tested under artificial saliva; however, the difference was only statistically significant for VM. Conclusions: The results indicate that the effect of water immersion on the flexural strength of dental porcelains varies according to their leucite content, as only the material without leucite in its microstructure (VM) showed significant strength degradation when tested under water.

The role of surface sealants in the roughness of composites after a simulated toothbrushing test

Objectives: To evaluate the influence of two surface sealants (BisCover/Single Bond) and three application techniques (unsealed/conventional/co-polymerization) on the roughness of two composites (Filtek Z250/Z350) after the toothbrushing test. Methods: Seventy-two rectangular specimens (5 mm x 10 mm x 3 mm) were fabricated and assigned into 12 groups (n = 6). Each sample was subjected to three random roughness readings at baseline, after 100,000 (intermediate), and 200,000 (final) toothbrushing strokes. Roughness (R) at each stage was obtained by the arithmetic mean of the reading of each specimen. Sealant removal was qualitatively examined (optical microscope) and classified into scores (0-3). Data were analyzed by Student`s paired t-test, two-way ANOVA/Tukey`s test, and by Wilcoxon, Kruskal-Wallis and Miller`s test (alpha = 0.05). Results: Z250 groups at baseline did not differ statistically from each other. Unsealed Z350 at baseline had lower R values. All the unsealed groups presented gradual decrease in R from baseline to final brushing. From baseline to the inter-mediate stage, Z250 co-polymerized groups presented a significant reduction in R (score 3). Conventionally sealed groups had no significant changes in R (scores 2-0.8). From baseline to the intermediate stage, the conventionally sealed Z350 Single Bond group had an increase in R (score 1.5). In the final stage, all the conventionally sealed groups presented a reduction in R (scores 0.7-0). Co-polymerized Single Bond groups had a significant reduction in R (scores 2.5-2.7), and co-polymerized BisCover groups an increase in R (scores 2.8-3). Conclusions: At any brushing stage, sealed composites presented superior performance when compared with unsealed composites. (C) 2009 Elsevier Ltd. All rights reserved.

Evaluation of the temperature of different refrigerant sprays used as a pulpal test

The temperature of different refrigerant sprays (Endo-Ice, Endo-Frost, Coolermatic and Sprayon Contact and Tuner Cleaner) used as pulpal tests were evaluated in vitro. A thermocouple placed inside the pulp chamber of a maxillary central incisor was used to register the temperature changes when the refrigerant sprays were applied with a cotton swab, for 10 s. Results indicate that Endo-Ice and Endo-Frost presented the lowest temperatures among the refrigerant sprays tested. Temperatures measured inside the pulp chamber, however, were statistically similar in all groups.

Influence of differently oriented dentin surfaces and the regional variation of specimens on adhesive layer thickness and bond strength

Statement of the Problem: Adhesive systems can spread differently onto a substrate and, consequently, influence bonding. Purpose: The purpose of this study was to evaluate the effect of differently oriented dentin surfaces and the regional variation of specimens on adhesive layer thickness and microtensile bond strength (MTBS). Materials and Methods: Twenty-four molars were sectioned mesiodistally to expose flat buccal and lingual halves. Standardized drop volumes of adhesive systems (Single Bond [SB] and Prime & Bond 2.1 [PB2.1]) were applied to dentin according to the manufacturer`s instructions. Teeth halves were randomly divided into groups: 1A-SB/parallel to gravity; 1B-SB/perpendicular to gravity; 2A-PB2.1/parallel to gravity; and 2B-PB2.1/perpendicular to gravity. The bonded assemblies were stored in 37 degrees C distilled water for 24 hours and then sectioned to obtain dentin sticks (0.8 mm(2)). The adhesive layer thickness was determined in a light microscope (x200), and after 48 hours the specimens were subjected to MTBS test. Data were analyzed by one-way and two-way analysis of variance and Student-Newman-Keuls tests. Results: Mean values (MPa +/- SD) of MTBS were: 39.1 +/- 12.9 (1A); 32.9 +/- 12.4 (1B); 52.9 +/- 15.2 (2A); and 52.3 +/- 16.5 (2B). The adhesive systems` thicknesses (mu m +/- SD) were: 11.2 +/- 2.9 (1A); 18.1 +/- 7.3 (1B); 4.2 +/- 1.8 (2A); and 3.9 +/- 1.3 (2B). No correlation between bond strength and adhesive layer thickness for both SB and PB2.1 (r = -0.224, p = 0.112 and r = 0.099, p = 0.491, respectively) was observed. Conclusions: The differently oriented dentin surfaces and the regional variation of specimens on the adhesive layer thickness are material-dependent. These variables do not influence the adhesive systems` bond strength to dentin. CLINICAL SIGNIFICANCE Adhesive systems have different viscosities and spread differently onto a substrate, influencing the bond strength and also the adhesive layer thickness. Adhesive thickness does not influence dentin bond strength, but it may impair adequate solvent evaporation, polymer conversion, and may also determine water sorption and adhesive degradation over time. In the literature, many studies have shown that the adhesive layer is a permeable membrane and can fail over timebecause ofits continuous plasticizing and degradation when in contact with water. Therefore, avoiding thick adhesive layers may minimize these problems and provide long-term success for adhesive restorations.

The mu-way intersection problem for m-cycle systems

An m-cycle system of order upsilon is a partition of the edge-set of a complete graph of order upsilon into m-cycles. The mu -way intersection problem for m-cycle systems involves taking mu systems, based on the same vertex set, and determining the possible number of cycles which can be common to all mu systems. General results for arbitrary m are obtained, and detailed intersection values for (mu, m) = (3, 4), (4, 5),(4, 6), (4, 7), (8, 8), (8, 9). (For the case (mu, m)= (2, m), see Billington (J. Combin. Des. 1 (1993) 435); for the case (Cc,m)=(3,3), see Milici and Quattrochi (Ars Combin. A 24 (1987) 175. (C) 2001 Elsevier Science B.V. All rights reserved.

Photoelastic Study of the Support Structures of Distal-Extension Removable Partial Dentures

Purpose: The double system of support, in which the distal-extension removable partial denture adapts, causes inadequate stress around abutment teeth, increasing the possibility of unequal bone resorption. Several ways to reduce or more adequately distribute the stress between abutment teeth and residual ridges have been reported; however, there are no definitive answers to the problem. The purpose of this study was to analyze, by means of photoelasticity, the most favorable stress distribution using three retainers: T bar, rest, proximal plate, I bar (RPI), and circumferential with mesialized rest. Materials and Methods: Three photoelastic models were made simulating a Kennedy Class II inferior arch. Fifteen dentures with long saddles, five of each design, were adjusted to the photoelastic patterns and submitted first to uniformly distributed load, and then to a load localized on the last artificial tooth. The saddles were then shortened and the tests repeated. The quantitative and qualitative analyses of stress intensity were done manually and by photography, respectively. For intragroup analyses the Wilcoxon test for paired samples was used, while for intergroup analyses Friedman and Wilcoxon tests were used to better identify the differences (p < 0.05). Results: The RPI retainer, followed by the T bar, demonstrated the best distribution of load between teeth and residual ridge. The circumferential retainer caused greater concentration of stress between dental apexes. Stress distribution was influenced by the type of retainer, the length of the saddle, and the manner of load application. Conclusions: The long saddles and the uniformly distributed loads demonstrated better distribution of stress on support structures.