Color stability and surface roughness of resin-ceramics with different surface treatments: A systematic review and meta-analysis of in vitro studies

STATEMENT OF PROBLEM

Surface treatments for resin-ceramics have been developed to obtain a smooth surface and improve color stability. However, a consensus on the best treatment for these materials is lacking.

PURPOSE

The purpose of this systematic review and meta-analysis was to evaluate the color stability and roughness of glass-ceramics versus resin-ceramics with different surface treatments.

MATERIAL AND METHODS

The preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were followed, and the study was registered in the open science framework (OSF) for in vitro studies. The population, intervention, control, and outcome (PICO) question was "Is there a difference in color stability and roughness between resin-ceramic vs vitreous ceramics in different surface treatment protocols?" A literature search was performed in PubMed/MEDLINE, Embase, Web of Science, Scopus, Cochrane Library, and ProQuest databases up to January 2023. The Joanna Briggs Institute's critical assessment guidelines for quasi-experimental studies were used for quality assessment. The meta-analysis was based on the inverse variance (IV) method (α=.05).

RESULTS

A total of 18 laboratory studies were published between 2015 and 2022, with a total of 2160 specimens, all of which were analyzed qualitatively. The meta-analysis indicated significantly less optical alteration for lithium disilicate ceramics (P<.01; MD: 2.69; 95% CI: 2.00-3.39; I²=89%, P<.01), even when compared with resin-ceramics with polish or sealants (P<.01; MD: 2.45; 95% CI: 1.59-3.30; I²=87%, P<.01) and (P<.01; MD: 3.24; 95% CI: 2.02-4.47; I²=89%, P<.01), while there was no significant difference in surface roughness (P=.08; MD: -0.71; CI 95%: -1.52 to 0.09; I²=87%, P<.01) (P=.33; MD: -0.31; CI 95%: -0.94 to 0.32; I²=87%, P<.01), respectively.

CONCLUSIONS

Resin-ceramics that have been polished or treated with sealants have lower color stability than glazed glass-ceramics; however, they are similar in terms of surface roughness.

Polyetheretherketone materials for removable partial denture frameworks: an integrative review

Polyetheretherketone (PEEK) resin is a high-performance thermoplastic polymer that has been introduced as a possible candidate to replace metallic components in dental prostheses. The objective of this integrative review was to compare, through analysis of studies in the literature, the mechanical performance of removable partial denture frameworks and clasps manufactured with PEEK with the performance of cobalt-chromium (Co-Cr) frameworks and clasps. The guiding question was, "Does the use of PEEK as a substitute for Co-Cr alloys for the construction of removable partial denture frameworks result in better mechanical properties?" The PubMed/ MEDLINE, Embase, Web of Science, Scopus, and SciELO databases were searched for articles published through October 2021. The JBI Critical Appraisal Checklist for Quasi-Experimental Studies was used to assess the methodologic quality of the selected in vitro studies. A total of 208 articles were identified. After the exclusion of duplicates and articles that did not meet the inclusion criteria, 7 studies- -4 in vitro and 3 three-dimensional finite element analyses- -published between 2012 and 2021 were included in the integrative review. The appraisal checklist revealed that the reviewed studies had a low risk of bias and high methodologic quality. The results of the review showed that PEEK alloys have adequate mechanical properties for use in clasps and removable partial denture frameworks, but Co-Cr alloys exhibit better mechanical properties and are more suitable in most circumstances.

Recombinogenic, genotoxic, and cytotoxic effects of azathioprine using in vivo assays

Azathioprine (Aza) is a purine antimetabolite immunosuppressant that is widely employed for immunosuppressive therapy in post-transplant recipients or patients with autoimmune diseases. Chronic use of immunosuppressants might produce several side effects, including a high rate of neoplasms in these patients. Considering that genotoxic effects are associated with an increased risk of developing cancer, the aim of this study was to examine the recombinogenic, genotoxic, and cytotoxic effects of Aza using Somatic Mutation and Recombination Test (SMART) in Drosophila melanogaster, as well as comet and micronucleus assays in mouse bone marrow cells. Further, the adverse effects of Aza were determined in mouse hepatic and renal tissues using histopathological analysis. Data demonstrated that Aza induced significant increased genotoxicity in D. melanogaster and mouse bone marrow cells at all concentrations tested. Homologous recombination was the predominant genotoxic event noted for the first time to be initiated by Aza in SMART. In histopathological analysis, Aza did not show any marked toxic activity in mouse hepatic and renal tissues. Therefore, the high rate of neoplasms reported in patients with long-term use of Aza may be attributed, at least partially, to the genotoxic action of this drug.

Metallic sample preparation for phase transformation analysis

Metallic materials characterization is a important part of phase transformation studies, and the sample preparation plays a crucial role in the measured properties. The methodologies available are not fully described and refer in its majority only to iron-based and aluminum-based alloys focusing in industrial analysis. In this paper the authors fully described the preparation methodology for metallic samples used by their research group. This method aims to attend different characterization techniques, producing samples of complex metallic systems from pure base materials by arc melting.

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The melting of metallic ingots from pure base materials was fully described.

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The correct sample cutting, sanding and polishing procedures were described.

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A full detailed procedure is described to prepare the samples for different analyses.

Full-dose intra-operative radiotherapy with electrons (ELIOT) during breast-conserving surgery: experience with 1246 cases

Background:

Previous studies showed that after breast-conserving surgery for breast cancer, radiotherapy may be applied to the portion of the breast where the primary tumour was removed (partial breast irradiation (PBI), avoiding the irradiation of the whole breast. We developed a procedure of PBI consisting of a single high dose of radiotherapy of 21 Gy with electrons equivalent to 58–60 Gy in fractionated doses, delivered during the surgical session by a mobile linear accelerator, positioned close to the operating table.

Patients and methods:

From July 1999 to December 2006, 1246 patients with primary carcinoma of less than 2.5-cm maximum diameter, mostly over 48 years, were treated with electron intra-operative radiotherapy (ELIOT) at a single dose of 21 Gy.

Results:

After a follow-up from 0.3 to 94.7 months (median 26), 24 (1.9%) patients showed a local recurrence and 22 developed distant metastases. Sixteen patients died, seven from breast carcinoma and nine from others causes. The five-year crude survival was 96.5%. Six (0.5%) developed severe breast fibrosis, which resolved in 2–3 years. An additional 40 patients suffered for mild fibrosis. Cosmetic results were good.

Conclusions:

Electron intra-operative radiotherapy is a safe method for treating conservatively operated breasts and avoids the long period of post-operative radiotherapy, greatly improving the quality of life and reduces the cost of radiotherapy. ELIOT markedly reduces the radiation to normal surrounding tissues and deep organs. Results on short- and medium-term toxicity are good. Data on local control are encouraging.

Synthesis and immunological activity of a branched peptide carrying the T-cell epitope of gp43, the major exocellular antigen of Paracoccidioides brasiliensis

The 43 kDa glycoprotein (gp43) of Paracoccidioides brasiliensis is the major diagnostic antigen of paracoccidioidomycosis (PCM), a prevalent fungal infection in South America. A 15-mer sequence from gp43, denominated P10, induced T-CD4+ T helper 1 cellular immune responses in mice of three different haplotypes and protected against intratracheal challenge by a virulent isolate of P. brasiliensis. In an attempt to improve delivery of P10, a promiscuous antigen also presented by human leucocyte antigen-DR alleles, aiming at immunotherapy, we synthesized a multiple antigen peptide with the protective T-cell epitope expressed in a tetravalent 13-mer analog of P10 (M10). M10 induced specific lymph node cell proliferation in mice preimmunized with peptides in complete Freund's adjuvant (CFA). In addition, M10 immunization without CFA significantly protected intratracheally infected mice. We conclude that M10 is a candidate for an anti-PCM vaccine. In this report we describe: (1) the synthesis of M10; (2) the induction of M10-elicited T-cell response and (3) in vivo protection of mice immunized with M10 and challenged by a virulent strain of P. brasiliensis.

[Prevalence and risk factors for anemia among children in Brazil]

OBJECTIVE

To verify the prevalence of anemia among children aged 0 to 36 months, who attend public day care centers in Porto Alegre, Brazil, and assess its possible risk factors.

METHODS

A cross-sectional study was carried out in 557 children aged 0 to 36 months of all public day care centers in Porto Alegre. Anthropometric measurements and hemoglobin levels were performed. The portable HemoCue photometer was employed to measure hemoglobin levels, and anemia was considered when the hemoglobin level was below 11 g/dl. Information regarding each child was obtained by means of a questionnaire applied to the mother. The association of the variables studied to anemia was analyzed using the log-binomial regression technique applied to the hierarchical model.

RESULTS

A 47.8% prevalence of anemia was found in this population. The risk factors for anemia in the studied group were: families with per capita income equal or less than one monthly minimal wage (prevalence ratio - RP =1.6), age between 12 and 23 months (RP=1.4), and having 2 or more siblings younger than 5 years old (RP=1.4).

CONCLUSIONS

There is a high prevalence of anemia among children aged 0 to 36 months in public day care centers, especially among children with the lowest socioeconomic level, in the 12 to 23 months age group, and who have 2 or more siblings under 5 years of age, indicating that there is an urgent need for effective measures to fight and prevent this condition.

Highly purified glycosylphosphatidylinositols from Trypanosoma cruzi are potent proinflammatory agents

Intracellular protozoan parasites are potent stimulators of cell-mediated immunity. The induction of macrophage proinflammatory cytokines by Trypanosoma cruzi is considered to be important in controlling the infection and the outcome of Chagas' disease. Here we show that the potent tumour necrosis factor-alpha-, interleukin-12- and nitric oxide-inducing activities of T.cruzi trypomastigote mucins were recovered quantitatively in a highly purified and characterized glycosylphosphatidylinositol (GPI) anchor fraction of this material. The bioactive trypomastigote GPI fraction was compared with a relatively inactive GPI fraction prepared from T. cruzi epimastigote mucins. The trypomastigote GPI structures were found to contain additional galactose residues and unsaturated, instead of saturated, fatty acids in the sn-2 position of the alkylacylglycerolipid component. The latter feature is essential for the extreme potency of the trypomastigote GPI fraction, which is at least as active as bacterial endotoxin and Mycoplasma lipopeptide and, therefore, one of the most potent microbial proinflammatory agents known.