Insights From a Community-Based Strategy to Assess Tobacco and Vape Shop Retailers' Implementation of Tobacco 21 Law in El Paso, Texas.

In 2019, the United States Congress passed Tobacco 21 (T21) legislation that raised the minimum legal sales age for tobacco products from 18 to 21. However, although the federal legislation superseded weaker state laws that were already in place in some states, including Texas, local guidance for retailers was inconsistent. Given that retailers are ultimately responsible for policy implementation, the American Heart Association (AHA) initiated a process of assessing retailers knowledge and perceptions of the law through a survey targeting all tobacco retailers and accompanying ethnography of a subset of vape shops in El Paso, Texas. The process yielded lessons learned for assessment of community-based policy implementation including key considerations for personnel and process that are applicable to other community-based assessment processes. While AHA considered an in-person approach ideal, having an alternate online response option was necessary. In addition, a focused approach and in-depth understanding of the purpose was key to responsiveness of the retailers.

Smoke-Free Policy Adoption in Horizon City and El Paso Community College: A Strategic Campaign Approach That Turns a "No" Into a "Yes".

Coalitions in Horizon City in El Paso County, Texas and the El Paso Community College (EPCC) had previously attempted to pass smoke-free policies in 2008 and 2016, respectively; however, both policies failed to pass at those times. The coalitions refocused their activities and were successful in passing policies in EPCC in 2020 and in Horizon City in 2021. We employed a participatory case study method to understand what factors changed between the first and second attempts at smoke-free policy adoption in Horizon City and EPCC. Using the Advocacy Coalition Framework as a basis for analysis, we identified the role of coalitions, their beliefs, use of power resources, role of policy brokers, and external events. We identify best practices and make recommendations for coalitions seeking to adopt smoke-free policies in other locations.

Effect of oxidation heat treatment with airborne-particle abrasion on the shear bond strength of ceramic to base metal alloys.

STATEMENT OF PROBLEM: Oxidation heat treatment has been studied to increase the metal-ceramic bond strength. However, information about its use with cobalt-chromium (Co-Cr) alloys is lacking. PURPOSE: The purpose of this study was to evaluate the effect of oxidation heat treatment and oxidation heat treatment with alumina airborne-particle abrasion on the metal-ceramic bond strength of Co-Cr alloys compared with that of nickel-chromium (Ni-Cr) alloys. MATERIAL AND METHODS: In total, 165 metal cylinders (∅5×8 mm) made of 5 base metal alloys were obtained by casting: 2 Ni-Cr (Fit Cast-SB and Fit Cast-V) and 3 Co-Cr alloys (Keragen, StarLoy C, and Remanium 2001). The specimens were divided into groups (n=11): no treatment, oxidation heat treatment, and oxidation heat treatment with airborne-particle abrasion. Oxidation heat treatment was performed starting at 650 °C and rising to 980 °C. The airborne-particle abrasion was performed with 100-µm alumina (0.2-MPa pressure, 5 seconds). One specimen had the surface topography and composition evaluated by scanning electron microscopy and energy dispersive X-ray spectrometry. The feldspathic ceramic was applied to the base metal alloy specimens (n=10). Shear tests were performed to obtain the metal-ceramic bond strength (MPa). The failure modes were evaluated. Data were evaluated by 2-way ANOVA and the Tukey post hoc test, Pearson correlation, and Fisher exact tests (α=.05). RESULTS: The group without treatment showed the highest roughness. The treatments increased oxygen and chromium levels and decreased nickel, molybdenum, and tungsten levels. Oxidation heat treatment provided an increase in metal-ceramic bond strength (P<.05) for base metal alloys with over 7% molybdenum (Fit Cast-SB, Fit Cast-V, and Remanium 2001). With oxidation heat treatment with airborne-particle abrasion, there was improvement only in Fit Cast-SB. No treatment was better for StarLoy C. A weak correlation was found between metal-ceramic bond strength and failure mode (ρ=.166; P=.043). The mixed failures were prevalent in Co-Cr alloys (P<.001) and oxidation heat treatment with airborne-particle abrasion (P=.008). CONCLUSIONS: The oxidation heat treatment was only beneficial for base metal alloy with a molybdenum content of over 7%. Although the oxidation heat treatment with alumina airborne-particle abrasion was a better treatment for Fit Cast-SB, its use is not justified because it showed no difference for oxidation heat treatment and requires another step in the surface treatment.

Effect of casting atmosphere on the marginal deficiency and misfit of Ni-Cr alloys with and without beryllium.

STATEMENT OF PROBLEM: The marginal adaptation of prosthetic crowns is still a significant clinical problem. PURPOSE: The purpose of this in vitro study was to evaluate the marginal deficiency and misfit of Ni-Cr alloys with and without beryllium under different casting conditions. MATERIAL AND METHODS: Four casting conditions were selected: flame-torch, induction/argon, induction/vacuum, and induction/air; and 2 alloys were used, Ni-Cr-Be and Ni-Cr. For each group, 10 metal specimens were prepared. Silicone indirect impressions and analysis of the degree of rounding were used to evaluate the marginal deficiencies of metal copings, and a standardized device for the setting pressure associated with optical microscopy was used to analyze the marginal misfit. Results were evaluated with 2-way ANOVA (α=.05), followed by the Tukey honest significant difference post hoc test, and the Pearson correlation test (α=.05). RESULTS: Alloy (P<.001) and casting technique (P<.001) were shown to affect marginal deficiencies. The Ni-Cr cast using the torch technique showed the highest marginal deficiency, and the Ni-Cr-Be cast in a controlled argon atmosphere showed the lowest (P<.001). Alloy (P=.472) and casting techniques (P=.206) did not affect the marginal misfit, but significant differences were found in the interaction (P=.001); the lowest misfit was achieved using the Ni-Cr-Be, and the highest misfit occurred with the molten Ni-Cr, using the cast torch technique. No correlation was found between deficiency and marginal misfit (r=.04, P=.69). CONCLUSIONS: The interactions demonstrated that the alloy containing beryllium that was cast in an argon atmosphere led to reduced marginal deficiency. Improved marginal adaptation can be achieved for the same alloy by using the torch technique.

Perspectives From the Field: Certified Health Education Specialists on the Value of Health Education Credentialing.

In this commentary, four Certified Health Education Specialists (CHESs) share their reasons for obtaining national certification as health education specialists, the value of national credentialing to their employers, and the career development benefits of National Commission for Health Education Credentialing certification. CHESs play a vital role in diverse research and practice settings and increasingly contribute to changes in practice and policy that promote health equity. National Commission for Health Education Credentialing certification enhances our individual capacity as public health educators and also enhances our profession through systematic verification of responsibilities, competencies, and subcompetencies. This commentary is particularly timely in light of the Health Education Specialist Practice Analysis 2015, which updated, refined, and validated the model of health education practice.

Immunogenicity of a prime-boost vaccine containing the circumsporozoite proteins of Plasmodium vivax in rodents.

Plasmodium vivax is the most widespread and the second most prevalent malaria-causing species in the world. Current measures used to control the transmission of this disease would benefit from the development of an efficacious vaccine. In the case of the deadly parasite P. falciparum, the recombinant RTS,S vaccine containing the circumsporozoite antigen (CSP) consistently protects 30 to 50% of human volunteers against infection and is undergoing phase III clinical trials in Africa with similar efficacy. These findings encouraged us to develop a P. vivax vaccine containing the three circulating allelic forms of P. vivax CSP. Toward this goal, we generated three recombinant bacterial proteins representing the CSP alleles, as well as a hybrid polypeptide called PvCSP-All-CSP-epitopes. This hybrid contains the conserved N and C termini of P. vivax CSP and the three variant repeat domains in tandem. We also generated simian and human recombinant replication-defective adenovirus vectors expressing PvCSP-All-CSP-epitopes. Mice immunized with the mixture of recombinant proteins in a formulation containing the adjuvant poly(I·C) developed high and long-lasting serum IgG titers comparable to those elicited by proteins emulsified in complete Freund's adjuvant. Antibody titers were similar in mice immunized with homologous (protein-protein) and heterologous (adenovirus-protein) vaccine regimens. The antibodies recognized the three allelic forms of CSP, reacted to the repeated and nonrepeated regions of CSP, and recognized sporozoites expressing the alleles VK210 and VK247. The vaccine formulations described in this work should be useful for the further development of an anti-P. vivax vaccine.

The Barretos Cancer Hospital Animal Facility: Implementation and Results of a Dedicated Platform for Preclinical Oncology Models.

The Barretos Cancer Hospital Animal Facility (BCHAF) is a unique facility in Brazil exclusively dedicated to working with animal models for cancer research. In this article, we briefly present our modern facility and the main experiments performed, focusing on mutant strains of mice (PTCH-knockout and ApcMin mice), xenograft models, and patient-derived xenografts (PDXs). Our results show the progress and challenges in establishing these models and the need for having an appropriate representation of our cancer population to better understand tumor biology and to identify cancer biomarkers, which could be putatively targeted, allowing for personalized therapy.

Effectiveness of chronic hepatitis C treatment with direct-acting antivirals in the Public Health System in Brazil.

INTRODUCTION: Chronic hepatitis C virus infection is one of the major causes of cirrhosis, hepatocellular carcinoma and liver transplantation. Treatment using direct-acting antivirals has revolutionized the treatment of hepatitis C virus, increasing long-term prognosis after cure. The goal of the present study was to evaluate the effectiveness of direct-acting antivirals in a Public Health System in southern Brazil. METHODS: A retrospective study evaluated all patients with chronic hepatitis C virus infection who underwent treatment at one center of the Public Health Department of the State of Rio Grande do Sul - Brazil, according to the Brazilian Clinical Protocol and Therapeutic Guidelines. The effectiveness was assessed in terms sustained virological response 12 weeks after the end of treatment. RESULTS: A total of 1002 patients who were treated for chronic hepatitis C virus infection were evaluated. The mean age was 58.6 years, 557 patients (55.6%) were male and 550 (54.9%) were cirrhotic. Overall sustained virological response was observed in 936 (93.4%) patients. There was a difference in sustained virological response rate varied according to sex, 91.6% in men and 95.7% in women (p = 0.009), length of treatment in genotype 1, 92.7% with 12 weeks and 99.1 with 24 weeks (p = 0.040), and genotype, 94.7% in genotype 1, 91.7% in genotype 2, and 91.4% in genotype 3 (p = 0.047). CONCLUSION: The treatment of chronic hepatitis C virus infection for genotypes 1, 2 or 3 with the therapeutic regimens established by the Brazilian guidelines showed high rates of SVR, even in cirrhotic patients.

Effect of Polyethylene Terephthalate Tongue Scraper on Oral Levels of Volatile Sulfur Compounds: a randomized clinical trial / Efeito do raspador de língua de polietilenotereftalato nos níveis orais de compostos sulfurados voláteis: um ensaio clínico randomizado

Objective: To evaluate the effect of Polyethylene Terephthalate (PET) tongue scraper on the volatile sulfur compound (VSC) levels. Material and Methods: A randomized, controlled, parallel design was used in this study. Out of the 48 volunteers from Dentistry Department of the Federal University of Sergipe, 40 subjects who met the inclusion criteria were randomly divided into 4 groups (n=10): G1 (control), rinsing of distilled water solution (WS); G2, WS and tongue coating removal (TCR) with toothbrush; G3, WS and TCR with a commercial tongue scraper; and G4, WS and TCR with PET tongue scraper. PET bottles were cut with a rectangular shape (1.0 cm wide x 20 cm long) to obtain PET tongue scraper. The VSC measurements were performed before (T0) and immediately after (T1) each therapy by portable sulfide monitor. Data (ppb) were submitted to Wilcoxon test (α=0.05). The differences between T0 and T1 were calculated and percentage values were assigned. Data (percentage) were submitted to ANOVA and Tukey test (α=0.05). Results: All 40 selected subjects completed the study. All groups reduced significantly the VSC levels after therapy (P<0.01). ANOVA indicated a significant difference among groups (P<0.001). The Tukey test showed that G1 (reduction of 21%) was similar to G2 (31%); G2 was similar to G3 (42%) and different from G4 (52%); G3 and G4 were similar. Conclusion: PET tongue scraper was similar to commercial tongue scraper and provided higher reductions of VSC levels than the toothbrush. (AU)

Objetivo: Avaliar o efeito do raspador de língua de polietilenotereftalato (PET) nos níveis de compostos sulfurados voláteis (CSVs). Material e Métodos: Um desenho paralelo, controlado e randomizado foi empregado neste estudo. Dos 48 voluntários do Departamento de Odontologia da Universidade Federal de Sergipe, 40 atenderam ao critério de inclusão e foram distribuídos aleatoriamente em 4 grupos (n=10): G1 (controle), bochecho com solução de água destilada (SA); G2, SA e remoção da saburra lingual (RSL) com escova dental; G3, SA e RSL com um raspador de língua comercial; e G4, SA e RSL com raspador de língua PET. Garrafas PET foram recortadas com uma forma retangular (1,0 cm de largura x 20 cm de comprimento) para obtenção dos raspadores de língua PET. As mensurações de CSVs foram realizadas antes (T0) e imediatamente após (T1) cada terapia usando um monitor portátil de enxofre. Os dados (ppb) foram submetidos ao teste de Wilcoxon (α=0,05). As diferenças entre T0 e T1 foram calculadas e transformadas em valores percentuais de redução. Os dados (percentuais) foram submetidos à ANOVA e ao teste de Tukey (α=0,05). Resultados: Todos os 40 indivíduos selecionados completaram o estudo. Em todos os grupos houve redução significante dos níveis de CSVs após terapia (P<0,01). ANOVA indicou uma diferença significante entre grupos (PP<0,001). O teste de Tukey mostrou que G1 (redução de 21%) foi semelhante a G2 (31%); G2 foi semelhante a G3 (42%) e diferente de G4 (52%); G3 e G4 foram semelhantes. Conclusão: O raspador de língua PET foi semelhante ao raspador de língua comercial e proporcionou maiores reduções de CSVs do que a escova dental. (AU)

Synchronization by food access modifies the daily variations in expression and activity of liver GABA transaminase.

Daytime restricted feeding (DRF) is an experimental protocol that influences the circadian timing system and underlies the expression of a biological clock known as the food entrained oscillator (FEO). Liver is the organ that reacts most rapidly to food restriction by adjusting the functional relationship between the molecular circadian clock and the metabolic networks. γ-Aminobutyric acid (GABA) is a signaling molecule in the liver, and able to modulate the cell cycle and apoptosis. This study was aimed at characterizing the expression and activity of the mostly mitochondrial enzyme GABA transaminase (GABA-T) during DRF/FEO expression. We found that DRF promotes a sustained increase of GABA-T in the liver homogenate and mitochondrial fraction throughout the entire day-night cycle. The higher amount of GABA-T promoted by DRF was not associated to changes in GABA-T mRNA or GABA-T activity. The GABA-T activity in the mitochondrial fraction even tended to decrease during the light period. We concluded that DRF influences the daily variations of GABA-T mRNA levels, stability, and catalytic activity of GABA-T. These data suggest that the liver GABAergic system responds to a metabolic challenge such as DRF and the concomitant appearance of the FEO.

Effect of investment type and mold temperature on casting accuracy and titanium-ceramic bond.

This study evaluated the casting accuracy of crown margins and metal-ceramic shear bond strength (SBS) of pure titanium injected into casting molds made using 2 investment types at 3 mold temperatures. Sixty crown (30-degree beveled finish line) and 60 cylinder (5mm diameter × 8mm high) patterns were divided into 6 groups (n=10), and cast using a phosphate-bonded investment (P) and a magnesium oxide-bonded investment (U), at 400°C (groups P400 and U400), 550°C (groups P550 and U550) and 700°C (groups P700 and U700) mold temperatures. Crown margins were recorded in impression material, the degree of marginal rounding was measured and margin length deficiencies (µm) were calculated. Titanium-ceramic specimens were prepared using Triceram ceramic (2mm high) and SBS was tested. Failure modes were assessed by optical microscopy. Data were subjected to two-way ANOVA and Tukey's HSD test (α=0.05). For casting accuracy, expressed by marginal deficiency (µm), investment U provided more accurate results (64 ± 11) than P (81 ± 23) (p<0.001). The increase in temperature resulted in different effects for the tested investments (p<0.001), as it provided better casting accuracy for U700 (55 ± 7) and worse for P700 (109 ± 18). Casting accuracy at 700°C (82 ± 31) was significantly different from 400°C (69 ± 9) and 550°C (68 ± 9) (p<0.05). For SBS, there was no significant differences among the groups for factors investment (p=0.062) and temperature (p=0.224), or for their interaction (p=0.149). Investment U provided better casting accuracy than investment P. The SBS was similar for all combinations of investments and temperatures.

Immunogenicity of recombinant proteins consisting of Plasmodium vivax circumsporozoite protein allelic variant-derived epitopes fused with Salmonella enterica Serovar Typhimurium flagellin.

A Plasmodium falciparum circumsporozoite protein (CSP)-based recombinant fusion vaccine is the first malaria vaccine to reach phase III clinical trials. Resistance to infection correlated with the production of antibodies to the immunodominant central repeat region of the CSP. In contrast to P. falciparum, vaccine development against the CSP of Plasmodium vivax malaria is far behind. Based on this gap in our knowledge, we generated a recombinant chimeric protein containing the immunodominant central repeat regions of the P. vivax CSP fused to Salmonella enterica serovar Typhimurium-derived flagellin (FliC) to activate the innate immune system. The recombinant proteins that were generated contained repeat regions derived from each of the 3 different allelic variants of the P. vivax CSP or a fusion of regions derived from each of the 3 allelic forms. Mice were subcutaneously immunized with the fusion proteins alone or in combination with the Toll-like receptor 3 (TLR-3) agonist poly(I·C), and the anti-CSP serum IgG response was measured. Immunization with a mixture of the 3 recombinant proteins, each containing immunodominant epitopes derived from a single allelic variant, rather than a single recombinant protein carrying a fusion of regions derived from each of 3 allelic forms elicited a stronger immune response. This response was independent of TLR-4 but required TLR-5/MyD88 activation. Antibody titers significantly increased when poly(I·C) was used as an adjuvant with a mixture of the 3 recombinant proteins. These recombinant fusion proteins are novel candidates for the development of an effective malaria vaccine against P. vivax.

Effectiveness of chronic hepatitis C treatment with direct-acting antivirals in the Public Health System in Brazil

ABSTRACT Introduction Chronic hepatitis C virus infection is one of the major causes of cirrhosis, hepatocellular carcinoma and liver transplantation. Treatment using direct-acting antivirals has revolutionized the treatment of hepatitis C virus, increasing long-term prognosis after cure. The goal of the present study was to evaluate the effectiveness of direct-acting antivirals in a Public Health System in southern Brazil. Methods A retrospective study evaluated all patients with chronic hepatitis C virus infection who underwent treatment at one center of the Public Health Department of the State of Rio Grande do Sul - Brazil, according to the Brazilian Clinical Protocol and Therapeutic Guidelines. The effectiveness was assessed in terms sustained virological response 12 weeks after the end of treatment. Results A total of 1002 patients who were treated for chronic hepatitis C virus infection were evaluated. The mean age was 58.6 years, 557 patients (55.6%) were male and 550 (54.9%) were cirrhotic. Overall sustained virological response was observed in 936 (93.4%) patients. There was a difference in sustained virological response rate varied according to sex, 91.6% in men and 95.7% in women (p= 0.009), length of treatment in genotype 1, 92.7% with 12 weeks and 99.1 with 24 weeks (p= 0.040), and genotype, 94.7% in genotype 1, 91.7% in genotype 2, and 91.4% in genotype 3 (p= 0.047). Conclusion The treatment of chronic hepatitis C virus infection for genotypes 1, 2 or 3 with the therapeutic regimens established by the Brazilian guidelines showed high rates of SVR, even in cirrhotic patients.

FRET peptides reveal differential proteolytic activation in intraerythrocytic stages of the malaria parasites Plasmodium berghei and Plasmodium yoelii.

Malaria is still a major health problem in developing countries. It is caused by the protist parasite Plasmodium, in which proteases are activated during the cell cycle. Ca(2+) is a ubiquitous signalling ion that appears to regulate protease activity through changes in its intracellular concentration. Proteases are crucial to Plasmodium development, but the role of Ca(2+) in their activity is not fully understood. Here we investigated the role of Ca(2+) in protease modulation among rodent Plasmodium spp. Using fluorescence resonance energy transfer (FRET) peptides, we verified protease activity elicited by Ca(2+) from the endoplasmatic reticulum (ER) after stimulation with thapsigargin (a sarco/endoplasmatic reticulum Ca(2+)-ATPase (SERCA) inhibitor) and from acidic compartments by stimulation with nigericin (a K(+)/H(+) exchanger) or monensin (a Na(+)/H(+) exchanger). Intracellular (BAPTA/AM) and extracellular (EGTA) Ca(2+) chelators were used to investigate the role played by Ca(2+) in protease activation. In Plasmodium berghei both EGTA and BAPTA blocked protease activation, whilst in Plasmodium yoelii these compounds caused protease activation. The effects of protease inhibitors on thapsigargin-induced proteolysis also differed between the species. Pepstatin A and phenylmethylsulphonyl fluoride (PMSF) increased thapsigargin-induced proteolysis in P. berghei but decreased it in P. yoelii. Conversely, E64 reduced proteolysis in P. berghei but stimulated it in P. yoelii. The data point out key differences in proteolytic responses to Ca(2+) between species of Plasmodium.

Time course of retinal degeneration associated with the absence of 1, 4, 5-inositol trisphosphate receptor in Drosophila melanogaster.

The absence of the inositol trisphosphate receptor is associated with a gradual retinal degeneration in Drosophila melanogaster. To characterize the time-course profile of this process, mosaic flies expressing a null allele of the itp gene in the eye were studied by electroretinograms and electronic microscopy. Membrane contour alterations, disrupted mitochondria, altered morphology and even loss of photoreceptors were increased progressively starting 5 d after hatching, were more evident during days 10-15 and promoted highly disorganized structures thereafter. Comparison between electroretinograms recorded in wild type and mutant tissues showed progressive differences in the on and off transients as well as in the magnitude of the summed receptor potentials of photoreceptor cells from day 5 of hatching, [corrected] and the functional defects became progressively more severe. Unexpectedly, these alterations were detected not only in the non-pigmented mutant ommatidia, but also in the pigmented ommatidia, including heterozygous and twin clones expressing 1, 4, 5-inositol trisphosphate receptor (IP(3)R). To explore the mechanism underlying this degenerative process, the progression of pro-oxidant and apoptotic reactions was characterized by immunohistochemical techniques. Mutant ommatidia showed intermittent episodes of increased pro-oxidant reactions (detected as adducts of 4-hydroxy-nonenal) throughout the fly's life. Similarly, several episodes of active caspase 3, an apoptotic effector, were evident with the same time pattern. Episodes of enhanced lipid peroxidation and apoptosis were also observed in the pigmented ommatidia of the mosaic eyes. The results indicate that photoreceptors lacking IP(3)R suffer episodes of increased lipid peroxidation, which eventually perturb the retinal subcellular organization and disrupt the phototransduction process and cell viability. Pigmented ommatidia also showed a similar pattern of damage, indicating that the degenerative process is non-autonomous and is so intense that it propagated to the non-mutant retinal cells in the mosaic eyes. In conclusion, ommatidia with a null mutation of IP(3)R degenerate by a process associated with intermittent lipid peroxidation and apoptotic activities.

Correlation between metal-ceramic bond strength and coefficient of linear thermal expansion difference.

The purpose of this study was to evaluate the metal-ceramic bond strength (MCBS) of 6 metal-ceramic pairs (2 Ni-Cr alloys and 1 Pd-Ag alloy with 2 dental ceramics) and correlate the MCBS values with the differences between the coefficients of linear thermal expansion (CTEs) of the metals and ceramics. Verabond (VB) Ni-Cr-Be alloy, Verabond II (VB2), Ni-Cr alloy, Pors-on 4 (P), Pd-Ag alloy, and IPS (I) and Duceram (D) ceramics were used for the MCBS test and dilatometric test. Forty-eight ceramic rings were built around metallic rods (3.0 mm in diameter and 70.0 mm in length) made from the evaluated alloys. The rods were subsequently embedded in gypsum cast in order to perform a tensile load test, which enabled calculating the CMBS. Five specimens (2.0 mm in diameter and 12.0 mm in length) of each material were made for the dilatometric test. The chromel-alumel thermocouple required for the test was welded into the metal test specimens and inserted into the ceramics. ANOVA and Tukey's test revealed significant differences (p=0.01) for the MCBS test results (MPa), with PI showing higher MCBS (67.72) than the other pairs, which did not present any significant differences. The CTE (10(-6) oC(-1)) differences were: VBI (0.54), VBD (1.33), VB2I (-0.14), VB2D (0.63), PI (1.84) and PD (2.62). Pearson's correlation test (r=0.17) was performed to evaluate of correlation between MCBS and CTE differences. Within the limitations of this study and based on the obtained results, there was no correlation between MCBS and CTE differences for the evaluated metal-ceramic pairs.

Effect of casting atmosphere on the shear bond strength of a ceramic to Ni-Cr and Ni-Cr-Be alloys.

The success of metal-ceramic restorations depends on an optimal bond between metal and ceramic. This study evaluated the effect of 3 casting atmospheres on the metal-ceramic bond strength (MCBS) of 2 Ni-Cr alloys, with beryllium (Fit Cast V) and without beryllium (Fit Cast SB). Sixty acrylic resin patterns (8 mm long and 5 mm diameter) were obtained using a fluorocarbon resin matrix. Wax was used to refine the surface of acrylic resin patterns that were invested and cast in an induction casting machine under normal, vacuum, and argon atmospheres at a temperature of 1340 degrees C. The castings were divested manually and airborne-particle abraded with 100-microm aluminum-oxide. Ten castings were obtained for each group. The IPS Classic V ceramic was applied (2 mm high and 5 mm diameter). The shear bond strength was tested in a mechanical testing machine with a crosshead speed of 2.0 mm/min. The MCBS data (MPa) were subjected to 2-way analysis of variance (alpha=0.05). There was no statistically significant difference (p>0.05) between the alloys or among the casting atmospheres. Within the limitations of this study, it may be concluded that the presence of beryllium and the casting atmosphere did not interfere in the MCBS of the evaluated metal-ceramic combinations.

Effect of investment type and mold temperature on casting accuracy and titanium-ceramic bond

This study evaluated the casting accuracy of crown margins and metal-ceramic shear bond strength (SBS) of pure titanium injected into casting molds made using 2 investment types at 3 mold temperatures. Sixty crown (30-degree beveled finish line) and 60 cylinder (5 mm diameter × 8 mm high) patterns were divided into 6 groups (n=10), and cast using a phosphate-bonded investment (P) and a magnesium oxide-bonded investment (U), at 400°C (groups P400 and U400), 550°C (groups P550 and U550) and 700°C (groups P700 and U700) mold temperatures. Crown margins were recorded in impression material, the degree of marginal rounding was measured and margin length deficiencies (µm) were calculated. Titanium-ceramic specimens were prepared using Triceram ceramic (2 mm high) and SBS was tested. Failure modes were assessed by optical microscopy. Data were subjected to two-way ANOVA and Tukey's HSD test (α=0.05). For casting accuracy, expressed by marginal deficiency (µm), investment U provided more accurate results (64 ± 11) than P (81 ± 23) (p<0.001). The increase in temperature resulted in different effects for the tested investments (p<0.001), as it provided better casting accuracy for U700 (55 ± 7) and worse for P700 (109 ± 18). Casting accuracy at 700°C (82 ± 31) was significantly different from 400°C (69 ± 9) and 550°C (68 ± 9) (p<0.05). For SBS, there was no significant differences among the groups for factors investment (p=0.062) and temperature (p=0.224), or for their interaction (p=0.149). Investment U provided better casting accuracy than investment P. The SBS was similar for all combinations of investments and temperatures.

O objetivo neste estudo foi avaliar a precisão da fundição de margens de coroas e a resistência de união metalocerâmica do titânio puro injetado em moldes de fundição feitos com 2 tipos de revestimentos em 3 diferentes temperaturas. Sessenta copings (com linha de término em bisel de 30°) e 60 padrões em forma de cilindros (diâmetro de 5 mm e altura de 8 mm) foram separados em 6 grupos (n=10) e fundidos usando revestimento aglutinado por fosfato (P) ou revestimento aglutinado por óxido de magnésio, nas temperaturas finais do molde: 400° (grupos P400 e U400), 550° (grupos P550 e U550) e 700° (grupos P700 e U700). As margens dos copings foram registradas em material de moldagem, o grau de arredondamento marginal foi medido e as deficiências marginais (µm) foram calculadas. Os espécimes metalocerâmicos foram confeccionados com cerâmica Triceram (altura de 2 mm) e submetidos aos ensaios de resistência de união por cisalhamento. Os tipos de fratura foram avaliados em microscópio óptico. Os dados foram submetidos à ANOVA e teste de Tukey (α=0,05). Para precisão de fundição (µm), o revestimento U promoveu melhores resultados (64 ± 11) que o P (81 ± 23) (p<0,001); o aumento da temperatura do molde resultou em efeitos diferentes para os revestimentos avaliados (p<0,001), considerando que promoveu melhor precisão de fundição para U700 (55 ± 7) e pior para P700 (109 ± 18). Os valores promovidos por 700°C (82 ± 31) foram significantemente diferentes de 400°C (69 ± 9) e 550°C (68 ± 9) (p<0,05). Para resistência de união ao cisalhamento, a ANOVA não demonstrou diferença significante para os fatores revestimento (p=0,062) e temperatura (p=0,224), nem para a interação deles (p=0,149). O revestimento U promoveu melhor precisão de fundição que o revestimento P. A resistência de união ao cisalhamento foi similar para todas as combinações de revestimentos e temperaturas do molde.

The castability of pure titanium compared with Ni-Cr and Ni-Cr-Be alloys.

STATEMENT OF PROBLEM: Titanium is the most biocompatible metal available for dental casting; however, there is great concern about its castability since this aspect of a casting metal/alloy has direct influence on the marginal fit of dental crowns. PURPOSE: The purpose of this study was to compare the castability of commercially pure titanium with 2 Ni-Cr base metal alloys. MATERIAL AND METHODS: Castability was evaluated indirectly by determining the sharpness of cast crown margins using the lost-wax technique. Castability was expressed in terms of the deficiency (mum) between an actual casting margin and a potentially perfect margin. Crown margins were recorded in a silicone impression material. The degree of marginal rounding was measured and margin length deficiencies (mum) were calculated. Sixty acrylic resin crown patterns with wax margins were prepared on a stainless steel stylized crown die having a 30-degree beveled finish line. The degree of wax margin rounding was determined in the control group (group W, n=15). The remaining 45 crown patterns were divided into 3 groups (n=15) and cast in commercially pure titanium (Tritan, group Ti), Ni-Cr-Be alloy (Verabond; group VB), and Ni-Cr alloy (Verabond II; group VBII). Margin configurations for both wax patterns and cast specimens were measured and recorded with the same method, using silicone impressions of the margins. After polymerization, the silicone material was sectioned in 8 locations through the margin area so that cross sections of the margins could be observed. Marginal deficiency was determined using microscopic measurements from the silicone sections and calculations. Data were subjected to 1-way ANOVA and Tukey HSD test (alpha=.05). RESULTS: Statistical analysis showed significant differences among the groups W, Ti, VB, and VBII (P<.001). The Tukey test revealed that Ti (108 +/-26 microm) was not significantly different from VBII (95 +/-35 microm), but was significantly different than Groups VB (22 +/-5 microm) and W (19 +/-6 microm), which were similar. CONCLUSIONS: Within the limitations of this study, the castability of titanium was poor compared to Ni-Cr-Be alloy, but similar to Ni-Cr alloy.

Effect of the use of die spacer on the marginal fit of copings cast in NiCr, NiCrBe and commercially pure titanium.

The goal of this study was to evaluate the effect of using die spacers on the marginal fit of NiCr (M1) and NiCrBe (M2) alloys and commercially pure titanium (cpTi) (M3) copings cast by the lost wax technique. Using a metal matrix, 45 resin added extra hard type IV stone models were obtained for the fabrication of wax patterns under the following conditions: no die spacer (A), with one die spacer layer (B) and with two die spacer layers (C), with five repetitions for each condition (alloy x die). Each die was waxed and the wax patterns were invested as per manufacturer's instructions. Three wax patterns were embedded in each casting ring, each corresponding to one of the conditions. Each coping, seated to the metal matrix by a seating pressure standardizing device (SPSD), was taken to an optical microscope for measurement of marginal discrepancy. The obtained data (microm) were analyzed statistically by ANOVA and Tukey' test (a=5%). There was statistically significant difference (p<0.05) among the materials (M1=110.67; M2=130.33 and M3=148.33). Regarding the use of the die spacer, there was a statistically significant difference (p<0.05) among the three conditions (A=162.00; B=131.06 and C=96.67). It was concluded that there is less marginal discrepancy with two die spacer layers.