Effect of artificial aging on mechanical and physical properties of CAD-CAM PMMA resins for occlusal splints.

PURPOSE: This study aimed to assess and compare the color stability, flexural strength (FS), and surface roughness of occlusal splints fabricated from heat-cured acrylic resin, milled polymethyl methacrylate (PMMA)-based resin, and 3D-printed (PMMA) based-resin. MATERIALS AND METHODS: Samples of each type of resin were obtained, and baseline measurements of color and surface roughness were recorded. The specimens were divided into three groups (n = 10) and subjected to distinct aging protocols: thermomechanical cycling (TMC), simulated brushing (SB), and control (without aging). Final assessments of color and surface roughness and three-point bending test (ODM100; Odeme) were conducted, and data were statistically analyzed (2-way ANOVA, Tukey, P <.05). RESULTS: Across all resin types, the most significant increase in surface roughness (Ra) was observed after TMC (P < .05), with the 3D-printed resin exhibiting the lowest Ra (P < .05). After brushing, milled resin displayed the highest Ra (P < .05) and greater color alteration (ΔE00) compared to 3D-printed resin. The most substantial ΔE00 was recorded after brushing for all resins, except for heat-cured resin subjected to TMC. Regardless of aging, milled resin exhibited the highest FS (P < .05), except when compared to 3D-printed resin subjected to TMC. Heat-cured resin exposed to TMC demonstrated the lowest FS, different (P < .05) from the control. Under control conditions, milled resin exhibited the highest FS, different (P < .05) from the brushed group. 3D-printed resin subjected to TMC displayed the highest FS (P < .05). CONCLUSION: Among the tested resins, 3D-printed resin demonstrated superior longevity, characterized by minimal surface roughness and color alterations. Aging had a negligible impact on its mechanical properties.

Whitening Effect of Different Toothpastes on Bovine Dental Enamel: an in situ study.

The aim of this in situ study was to evaluate color change, surface roughness, gloss, and microhardness in tooth enamel submitted to whitening and remineralizing toothpastes. Fifteen healthy adults (REBEC - RBR-7p87yr) (with unstimulated salivary flow ≥ 1.5 ml for 5 minutes, pH=7) wore two intraoral devices containing four bovine dental fragments (6 x 6 x 2 mm). Participants were randomly assigned and instructed to toothbrush the devices with the tested toothpastes (30 days): CT: conventional; WT: whitening; WTP: whitening with peroxide, and RT: remineralizing toothpaste. A washout period of 7 days was established. Readouts of color, gloss, surface roughness, and microhardness were performed before and after brushing. The results demonstrated no color, gloss, and microhardness differences (p>0.5). The samples brushed with WTP (0.2(0.7) showed higher surface roughness (p=0.0493) than those with WT (-0.5(1.0). The toothpastes did not alter the properties of the dental enamel, except for the roughness. Toothpaste with an abrasive system based on sodium bicarbonate and silica, and that contains sodium carbonate peroxide increased the surface roughness of the enamel.

Whitening Effect of Different Toothpastes on Bovine Dental Enamel: an in situ study

Abstract The aim of this in situ study was to evaluate color change, surface roughness, gloss, and microhardness in tooth enamel submitted to whitening and remineralizing toothpastes. Fifteen healthy adults (REBEC - RBR-7p87yr) (with unstimulated salivary flow ≥ 1.5 ml for 5 minutes, pH=7) wore two intraoral devices containing four bovine dental fragments (6 x 6 x 2 mm). Participants were randomly assigned and instructed to toothbrush the devices with the tested toothpastes (30 days): CT: conventional; WT: whitening; WTP: whitening with peroxide, and RT: remineralizing toothpaste. A washout period of 7 days was established. Readouts of color, gloss, surface roughness, and microhardness were performed before and after brushing. The results demonstrated no color, gloss, and microhardness differences (p>0.5). The samples brushed with WTP (0.2(0.7) showed higher surface roughness (p=0.0493) than those with WT (-0.5(1.0). The toothpastes did not alter the properties of the dental enamel, except for the roughness. Toothpaste with an abrasive system based on sodium bicarbonate and silica, and that contains sodium carbonate peroxide increased the surface roughness of the enamel.

Resumo O objetivo deste estudo in situ foi avaliar a alteração de cor, rugosidade superficial, brilho e microdureza em esmalte dentário submetido a dentifrícios clareadores e remineralizantes. Quinze adultos saudáveis (REBEC - RBR-7p87yr) (com fluxo salivar não estimulado ≥ 1.5 mL por 5 minutos, pH = 7) usaram dois dispositivos intrabucais contendo quatro fragmentos dentários bovinos (6 x 6 x 2 mm). Os participantes foram aleatoriamente designados e instruídos a escovar os aparelhos com os dentifrícios testados (30 dias): CO: convencional; CL: clareador; CLP: clareador com peróxido e RE: remineralizante. Foi estabelecido um período de washout de 7 dias. Leituras de cor, brilho, rugosidade superficial e microdureza foram realizadas antes e após a escovação. Os resultados não demonstraram diferenças na cor, brilho e microdureza. As amostras escovadas com CLP apresentaram maior rugosidade superficial (p=0,0493) do que aquelas com CL. Os dentifrícios não alteraram as propriedades do esmalte dental, exceto a rugosidade. O dentifrício com sistema abrasivo à base de bicarbonato de sódio e sílica, e que contém peróxido de carbonato de sódio aumentou a rugosidade de superfície do esmalte.

Effect of phytosphingosine on staining resistance and microhardness of tooth enamel.

OBJECTIVE: To evaluate the protective effect of phytosphingosine (PHS) against staining on dental enamel. MATERIALS AND METHODS: Ninety-six specimens of bovine teeth (6 mm × 6 mm × 2 mm) were cut, and initial color (Easyshade, VITA), microhardness (HMV-2, Shimadzu) and fluorescence (Matlabs software, Matworks) measurements were performed. Specimens were separated into four groups according to the treatments: Distilled water (control); Human saliva (HS); PHS; PHS + HS. Specimens (n = 6) were submitted to staining procedures: Distilled water (immersion for 30 days-control); Coffee (15 minutes, twice a day/for 15 days); Black tea (as described for Coffee) and cigarette smoke (20 cigarettes/sample). Final measurements were performed, and data were analyzed (Color-CIEDE2000, fluorescence-2-way ANOVA, Tukey, and microhardness-Kruskal-Wallis Dunn, P < .05). RESULTS: Coffee caused the highest color change (ΔE00 ), followed by black tea, regardless of the treatment employed. Distilled water and cigarette smoke produced similar color changes (P > .05) for the groups control (water = 1.0 + - 0.5/ cigarette = 2.3 0.3) and PHS (water = 0.8 0.4/ cigarette = 2.3 0.4). PHS + HS demonstrated intermediate means than PHS and HS when stained with coffee and tea. After treatments, the least fluorescence alterations occurred for the groups treated with distilled water and cigarette, regardless of the treatment, with no difference (P > .05) between them. There was a significant difference (P < .05) on microhardness between all the groups, as PHS + HS > PHS > HS > Distilled water. CONCLUSIONS: It was concluded that PHS treatment did not protect the staining of the enamel by coffee and tea, but increased the microhardness, both in the presence and absence of a salivary pellicle. PRACTICAL IMPLICATIONS: Phytoshingosine is a novel agent and considered a promising component for anti-biofilm and anti-erosion properties by the formation of a diffusion barrier on the dental enamel. In line, PHS might be considered for anti-staining purposes.

The Recombinant Protein Based on Trypanosoma cruzi P21 Interacts With CXCR4 Receptor and Abrogates the Invasive Phenotype of Human Breast Cancer Cells.

Trypanosoma cruzi P21 is a protein secreted by the parasite that plays biological roles directly involved in the progression of Chagas disease. The recombinant protein (rP21) demonstrates biological properties, such as binding to CXCR4 receptors in macrophages, chemotactic activity of immune cells, and inhibiting angiogenesis. This study aimed to verify the effects of rP21 interaction with CXCR4 from non-tumoral cells (MCF-10A) and triple-negative breast cancer cells (MDA-MB-231). Our data showed that the MDA-MB-231 cells expressed higher levels of CXCR4 than did the non-tumor cell lines. Besides, cytotoxicity assays using different concentrations of rP21 showed that the recombinant protein was non-toxic and was able to bind to the cell membranes of both cell lineages. In addition, rP21 reduced the migration and invasion of MDA-MB-231 cells by the downregulation of MMP-9 gene expression. In addition, treatment with rP21 blocked the cell cycle, arresting it in the G1 phase, mainly in MDA-MB-231 cells. Finally, rP21 prevents the chemotaxis and proliferation induced by CXCL12. Our data showed that rP21 binds to the CXCR4 receptors in both cells, downregulates CXCR4 gene expression, and decreases the receptors in the cytoplasm of MDA-MB-231 cells, suggesting CXCR4 internalization. This internalization may explain the desensitization of the receptors in these cells. Thus, rP21 prevents migration, invasion, and progression in MDA-MB-231 cells.

Effect of Methods of Biosilicate Microparticle Application on Dentin Adhesion.

Restorative procedures associated with bioglasses have shown to be a strategy to satisfy the contemporary concept of minimally invasive dentistry. Thus, the aim of this study was to evaluate bond strength to dentin treated by two different methods of biosilicate microparticle application. Dentin surfaces from 30 sound human molars were exposed and randomly assigned into three groups (n = 10) according to the surface treatment: (1) blasting with biosilicate microparticles (distance = 1 cm/pressure = 5 bar/time = 1 min); (2) 10% biosilicate microparticles paste; and (3) control (no treatment). After, dentin surfaces were restored with self-etch adhesive (Adper Easy Bond) and nanofilled composite (Filtek Z350). Specimens were sectioned perpendicularly to the adhesive interface to obtain sticks (cross-section area = 1 mm²), which were submitted to microtensile test (0.5 mm/min; 50 kgf). Data were analyzed by ANOVA and Tukey's test (α = 5%). Dentin/adhesive interfaces were morphologically analyzed by scanning electron microscopy (SEM). Data analysis showed that biosilicate-treated groups reached similar results (p > 0.05) and both of them demonstrated higher values (p < 0.05) than control group. SEM micrographs revealed hybridization with clear resin tags and no separation between resin-dentin adhesive interfaces. Within the limitations of this study, surface treatment with biosilicate positively influenced the adhesion to dentin and does not alter the morphology of the adhesive interface.

Assessment of carcinogenic potential of soft drinks of cola, diet cola, orange and lemon, produced in the city of Uberlândia, Minas Gerais state, Brazil / Avaliação do potencial carcinogênico de refrigerantes à base de cola, diet cola, laranja e limão, produzidos no município de Uberlândia, estado de Minas Gerais, Brasil

Soft drinks are industrialized unfermented beverages, free of alcohol, carbonated, rich in artificial flavors and sugar. The intense consumption of such beverages can be related to not inheritable diseases such as caries, allergy, cellulite and stretch marks, gastrointestinal disorders, diabetes and cancer. The aim of this study was to evaluate the carcinogenic potential of different concentrations of soft drinks produced in the Uberlândia city, Minas Gerais State, Brazil, by means of Epithelial Tumor Detection Test using Drosophila melanogaster as a model. Third stage larvae descendants of crosses between D. melanogaster virgin females wts/TM3, sb¹ and males mwh/mwh were treated with different concentrations (0.83, 1.66 or 3.33 mL/g) of cola, diet cola, orange or lemon soft drinks. The total epithelial tumor rate observed in flies treated with 3.33 mL/g of cola and orange soft drinks was higher than the negative control. The diet cola and lemon caused no significant increase in the overall frequency of epithelial tumors in D. melanogaster. In conclusion, in these experimental conditions, the cola and orange base soft drinks demonstrated carcinogenic potential in somatic cells of D. melanogaster in the concentration of 3.33 mL/g.

Refrigerantes são bebidas industrializadas não fermentadas, livre de álcool, carbonatadas, ricas em aromas artificiais e açúcar. O consumo intenso dessas bebidas pode estar relacionada à doenças não herdáveis como, cáries, quadros alérgicos, formação de celulite e estrias cutâneas, alterações gastrointestinais, diabetes e câncer. O objetivo desse trabalho foi avaliar o potencial carcinogênico de diferentes concentrações de refrigerantes produzidos no município de Uberlândia, Estado de Minas Gerais, Brasil. Foi realizado o Teste de Detecção de Tumor Epitelial em Drosophila melanogaster. Larvas de terceiro estágio descendentes do cruzamento entre fêmeas virgens wts/TM3, sb¹ e machos mwh/mwh de D. melanogaster foram tratadas com diferentes concentrações (0,83; 1,66 ou 3,33 mL/g) de refrigerantes à base de cola, diet cola, laranja e limão. Os resultados mostraram aumento na frequência de tumor epitelial em moscas tratadas 3,33 mL/g de refrigerantes à base de cola e de laranja, quando comparados ao controle negativo. Os refrigerantes diet cola e limão não provocaram aumento na frequência de tumor epitelial em D. melanogaster. Em conclusão, nessas condições experimentais, os refrigerantes à base de cola e laranja mostraram potencial carcinogênico em células somáticas de D. melanogaster na concentração de 3,33 mL/g.

Biocompatibility of new calcium aluminate cement (EndoBinder).

INTRODUCTION: The purpose of this study was to evaluate the biocompatibility of calcium aluminate cement (EndoBinder) in subcutaneous tissue of rats. METHODS: Fifteen rats, weighing 300 g, were separated into 3 groups (n = 5) in accordance with the time of death (7, 21, 42 days). Two incisions were made in the dorsal subcutaneous tissue of each rat in which were implanted 2 polyethylene tubes filled with the test materials, EndoBinder (EB) and Grey MTA (GMTA). The external tube walls were considered the negative control group (CG). After 7, 21, and 42 days, animals were killed, obtaining 5 samples per group, at each time interval of analysis. RESULTS: From the morphologic and morphometric analyses by using a score of (0-3) (50, 100, and 400×), results showed absence of inflammatory reaction (0) for EB after 42 days. However, for GMTA, a slight inflammatory reaction (1) was observed after 42 days, which means the persistence of a chronic inflammatory process. When compared with CG, tissue reaction ranging from discrete (1-7 days) to absent (0-42 days) was observed. CONCLUSIONS: EndoBinder presented satisfactory tissue reaction; it was biocompatible when tested in subcutaneous tissue of rats.

Color stability, surface roughness, and surface porosity of acrylic resins for eye sclera polymerized by different heat sources.

PURPOSE: The aim of this study was to evaluate the color stability, surface roughness, and surface porosity of acrylic resins for eye sclera polymerized by different heat sources and submitted to accelerated artificial aging (AAA). MATERIALS AND METHODS: Three groups of ten specimens each were formed according to the heat source used during the polymerization cycle: GI-short cycle, GII-long cycle, and GIII-dry-heat oven. The groups were submitted to color spectrophotometry through the CIE L a b system and to surface roughness and porosity analysis using a Surfcorder IF 1700 profilometer. After the tests, specimens were submitted to AAA, with a maximum aging time of 384 hours, corresponding to a year of clinical use. After aging, the color and roughness of each group were assessed. RESULTS: The results showed that the variability of DeltaE was clinically unacceptable for all groups but the method of polymerization was insignificant (p > 0.05) for color change. For roughness, polymerization cycle was significant for the results. GIII (0.23 +/- 0.06) presented the highest roughness difference (before and after AAA), statistically significant (p < 0.05) from GII. No statistically significant difference could be found among groups when considering the porosity test. CONCLUSION: It may be concluded that irrespective of the type of heat used for polymerization, there was an intense color alteration, to clinically unacceptable levels, when the specimens were submitted to AAA. For the other properties, alterations were less intense.