Effect of impeller type on cellular morphology and production of clavulanic acid by Streptomyces clavuligerus.

It is essential to evaluate the effects of operating conditions in submerged cultures of filamentous microorganisms. In particular, the impeller type influences the flow pattern, power consumption, and energy dissipation, leading to differences in the hydrodynamic environment that affect the morphology of the microorganism. This work investigated the effect of different impeller types, namely the Rushton turbine (RT-RT) and Elephant Ear impellers in up-pumping (EEUP) and down-pumping (EEDP) modes, on cellular morphology and clavulanic acid (CA) production by Streptomyces clavuligerus in a stirred-tank bioreactor. At 800 rpm and 0.5 vvm, the cultivations performed using RT-RT and EEUP impellers provided higher shear conditions and oxygen transfer rates than those observed with EEDP. These conditions resulted in higher clavulanic acid production using RT-RT (380.7 mg/L) and EEUP (453.3 mg/L) impellers, compared to EEDP (196.6 mg/L). Although the maximum CA concentration exhibited the same order of magnitude for RT-RT and EEUP impellers, the latter presented 40% of the specific power consumption (4.9 kW/m3) compared to the classical RT-RT (12.0 kW/m3). The specific energy for CA production ( E CA ), defined as the energy cost to produce 1 mg of CA, was 3.5 times lower using the EEUP impeller (1.91 kJ/mgCA) when compared to RT-RT (5.91 kJ/mgCA). Besides, the specific energy for O2 transfer ( E O 2 ), the energy required to transfer 1 mmol of O2, was 2.3 times lower comparing the EEUP impeller (3.28 kJ/mmolO2) to RT-RT (7.65 kJ/mmolO2). The results demonstrated the importance of choosing the most suitable impeller configuration in conventional bioreactors to manufacture bioproducts.

A proof-of-principle for decontamination of transplantation kidney through UV-C exposition of the perfusate solution.

Kidney transplantation is a common yet highly demanding medical procedure worldwide, enhancing the quality of life for patients with chronic kidney disease. Despite its prevalence, the procedure faces a shortage of available organs, partly due to contamination by microorganisms, leading to significant organ disposal. This study proposes utilizing photonic techniques associated with organ support machines to prevent patient contamination during kidney transplantation. We implemented a decontamination system using ultraviolet-C (UV-C) irradiation on the preservation solution circulating through pigs' kidneys between harvest and implant. UV-C irradiation, alone or combined with ultrasound (US) and Ps80 detergent during ex-vivo swine organ perfusion in a Lifeport® Kidney Transporter machine, aimed to reduce microbiological load in both fluid and organ. Results show rapid fluid decontamination compared to microorganism release from the organ, with notable retention. By including Ps80 detergent at 0.5% during UV-C irradiation 3 log10 (CFU mL-1) of Staphylococcus aureus bacteria previously retained in the organ were successfully removed, indicating the technique's feasibility and effectiveness.

The design strain sensitivity of the schenberg spherical resonant antenna for gravitational waves.

The main purpose of this study is to review the Schenberg resonant antenna transfer function and to recalculate the antenna design strain sensitivity for gravitational waves. We consider the spherical antenna with six transducers in the semi dodecahedral configuration. When coupled to the antenna, the transducer-sphere system will work as a mass-spring system with three masses. The first one is the antenna effective mass for each quadrupole mode, the second one is the mass of the mechanical structure of the transducer first mechanical mode and the third one is the effective mass of the transducer membrane that makes one of the transducer microwave cavity walls. All the calculations are done for the degenerate (all the sphere quadrupole mode frequencies equal) and non-degenerate sphere cases. We have come to the conclusion that the "ultimate" sensitivity of an advanced version of Schenberg antenna (aSchenberg) is around the standard quantum limit (although the parametric transducers used could, in principle, surpass this limit). However, this sensitivity, in the frequency range where Schenberg operates, has already been achieved by the two aLIGOs in the O3 run, therefore, the only reasonable justification for remounting the Schenberg antenna and trying to place it in the sensitivity of the standard quantum limit would be to detect gravitational waves with another physical principle, different from the one used by laser interferometers. This other physical principle would be the absorption of the gravitational wave energy by a resonant mass like Schenberg.

Subsistence swine farming: seroprevalence and risk factors associated with Lawsonia intracellularis infection in the state of Minas Gerais Brazil in 2016.

Although it is considered an economically relevant and prevalent disease, little information is available on the epidemiology and risk factors of porcine proliferative enteropathy (PPE) in commercial pigs, and no publication is available on subsistence pig farming. The objectives of this study were to estimate the seroprevalence of L. intracellularis and identify associated risk factors in backyard pigs in the 12 mesoregions of the state of Minas Gerais, Brazil. Blood from pigs between 2 months and 6 years of age were sampled; an epidemiological questionnaire was applied to 288 properties investigated in 2016. Serum samples were tested for the presence of anti-L. intracellularis antibodies using an immunoperoxidase monolayer assay. The seroprevalence of L. intracellularis was 97.7% (CI 95%: 96.7-98.4), and there was no statistical difference among the prevalence of the sampled mesoregions. Only 3 of the 12 risk factors were significant when samples were analyzed from strongly seropositive animals (≥ 1:120) in a Poisson multivariate regression model. There was an interaction between properties in peri-urban areas and extensive production systems. This interaction demonstrated an increase in prevalence rates by 3.7 times (95%CI: 2.4-5.8). Properties close to dumps demonstrated an increase in prevalence rates by 2.2 times (95%CI: 0.99-4.8). In conclusion, anti-L. intracellularis antibodies were widely dispersed in subsistence pig farming's in Minas Gerais, indicating a wide circulation of the agent in this type of production system. The interactions of animals raised close to peri-urban areas, extensively, and close to landfills are risk factors for spread of PPE.

First evidence of environmental bioaccumulation of pharmaceuticals on adult native anurans (Rhinella arenarum) from Argentina.

The presence of pharmaceutically active compounds (PhACs) in surface water is well known, whereas their natural occurrence in biota is much less explored. The aim of this work was to evaluate the bioaccumulation of PhACs in adult toads of the neotropical species Rhinella arenarum. Three sites were selected in Buenos Aires (Argentina): a reference site (Site 1), a site with direct discharge from a secondary wastewater treatment plant (WWTP) (Site 2) and a site 300 m downstream of the WWTP discharge (Site 3). Surface water samples, as well as muscle, liver and fat bodies of toads were collected, extracted and analyzed by LC-MS/MS. Highly significant differences in total PhACs concentration in surface water (p < 0.005) were detected between Site 2 and the other sites. These concentrations ranged from 0.37 to 52.46 ng/L at Site 1, 0.71-6950.37 ng/L at Site 2, and 0.12-75.45 ng/L at Site 3. In general, bioaccumulation of PhACs in toad tissues was similar between sites and tissues of each site. The highest concentrations were detected in the muscle of toads from Site 3 (1.06-87.24 ng/g dw), followed by liver (1.77-38.10 ng/g dw) and fat bodies (0.68-20.59 ng/g dw) from Site 1. Ibuprofen (6950 ng/L), acetaminophen (3277 ng/L) and valsartan (2504 ng/L) were the compounds with the highest concentrations in surface water from Site 2, whereas acetaminophen (87.2 ng/g dw, muscle from Site 3), desloratadine (38.1 ng/g dw, liver from Site 1), and phenazone (25.9 ng/g dw, liver from Site 1) were the ones that showed the highest concentrations in biota. This is the first time a field study has examined the environmental bioaccumulation of PhACs in anurans, demonstrating their potential for monitoring the status of natural ecosystems.

Does endodontics influence radiological detection of external root resorption? an in vitro study.

BACKGROUND: External root resorption (ERR) has a multifactorial etiology and is difficult to diagnose, which means that is continues to be of research interest. This work mainly aims to determine whether external root resorption can be differentially detected in root-filled versus non-endodontically treated teeth using digital periapical radiography (DPR) and cone-beam computed tomography (CBCT). METHODS: The Checklist for Reporting In-vitro Studies (CRIS) guidelines were followed throughout this study. This experiment highlights the preparation and generation of standardized synthetic teeth measured on three-dimensional records converted into Digital Imaging and Communication on Medicine (DICOM) file format. Twelve replicate maxillary incisors were randomized into two groups: (G1) six non-endodontically treated, and (G2) six endodontically treated teeth. In both groups, actual tooth lengths of all specimens were measured and compared with measurements obtained using DPR and CBCT. Simulated ERR lesions [0.12, 0.18, 0.20 mm × 0.5 mm depth in the mesial, distal and palatal apical regions] were created progressively, radiographic images were recorded, and 24 DPRs and 96 CBCTs were obtained in total. Eight blinded, previously calibrated researchers made a total of 1920 measurements (using Horos Software). Data were analyzed using the Shapiro-Wilk, ANOVA, Kruskal-Wallis and Wilcoxon rank post-hoc tests [Bonferroni correction in multiple comparison tests (p < 0.05)]. RESULTS: ICC values for intra- and inter-examiner agreement were appropriate. DPR overestimated ERR detection compared to the actual and CBCT measurements [Mean diff = 0.765 and 0.768, respectively]. CBCT diagnosis of ERR lesions in specimens without root canal treatment was significantly more accurate than DPR diagnoses on both non-endodontically and endodontically-treated specimens [p = 0.044; p = 0.037, respectively]. There was an 18.5% reduction in sensitivity in all DPR diagnoses made on endodontic teeth versus those made on non-endodontically treated teeth. For the smallest ERR lesions, this sensitivity was even more marked, with 27.8 and 25% less sensitivity, respectively. CONCLUSIONS: The results of this study highlight that both CBCT and DPR are good diagnostic methods for ERR. Nevertheless, root canal filling material influences diagnostic capability in ERR. The clinical significance was that the presence of intracanal material reduces the detection and diagnosis of ERR by DPR in teeth with root canal treatment.

Biological role of the bidirectional interaction between epithelial-mesenchymal transition and PD-L1 expression in head and neck squamous cell carcinomas: A systematic review.

BACKGROUND: Squamous cell carcinoma (SCC) is the most common head and neck malignant neoplasm. Despite progress in antineoplastic treatment for SCC, there are still high morbidity and mortality rates. Over the years, several tumor biomarkers have been suggested to predict the prognosis of patients with oral SCC. Studies point to a bidirectional association between the epithelial-mesenchymal transition (EMT) and the expression of PD-L1 with the aggressive biological behavior of the neoplastic cell. Thus, this systematic review aimed to explore the biological roles and mechanisms underlying the interaction between EMT and PD-L1 expression in head and neck SCC-derived cell lines. MATERIAL AND METHODS: An electronic search was performed in the PubMed/Medline, Web of Science, Science Direct, Scopus, Embase, and Cochrane Collaboration Library databases. Articles evaluating the in vitro relationship between EMT/PD-L1 interaction and the biological behavior of head and neck SCC cell lines were selected for this systematic review. The quality of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria. RESULTS: After applying the previously established inclusion/exclusion criteria, 9 articles were included in the qualitative synthesis. The present systematic review suggests the existence of a bidirectional interaction between EMT and PD-L1 expression, which is related to alterations in the cell cycle, proliferation, apoptosis, and cell survival, affecting the migration and invasion ability of tumor cells. CONCLUSIONS: Combined targeting of the two pathways may be potentially effective for immunotherapy in head and neck SCC.

In vitro fertilization: an unexpected finding in a cohort of patients with biliary atresia.

In biliary atresia (BA), efforts to prevent premature liver transplantation (LT) are aimed at early diagnosis, timing of Kasai-portoenterostomy (KPE), and centralization of care. This report presents the clinical picture, treatment strategies, and outcomes of BA patients with no previous treatment. A retrospective cohort study (Jan/2001 to Jan/2021) was conducted to evaluate the outcome of patients with BA referred to a single team. Study groups were: 1) Kasai-only group (K-only) n=9), 2) LT-only group (n=7), and 3) Kasai+LT group (K+LT) (n=23). Survival with native liver and overall survival were 22.9 and 94.8%, respectively, at 120 months of follow-up. There was no difference in age at KPE in the K-only group (46.8±21.8 days) vs K+LT (52.1±22 days), P=0.4. Ten (25.6%) patients were babies conceived through in vitro fertilization (IVF). Four IVF patients (40%) presented associated congenital heart disease vs 5 patients (17%) in the remaining group (P=0.14). Two of the IVF patients were premature (<37 weeks). Median maternal age at birth was 35 years (33 to 41 years). Excellent patient survival is expected for patients with BA with the available treatment strategies. IVF+BA was an unexpected prevalent association in this cohort, and further studies are required to better understand these findings.

Carcass, meat quality traits, and economic analysis of Nellore bulls fed with finishing feedlot diets containing mechanically processed corn silage.

Effects of mechanical processing (MP) of corn silage and its inclusion in feedlot diets on carcass and meat quality traits of Nellore (Bos indicus) were analyzed. Seventy-two bulls aged approximately 18 months and with an initial average body weight of 392.8 ± 22.3 kg were used. The experimental design was a 2 × 2 factorial arrangement, considering the concentrate-roughage (C:R) ratio (40:60 or 20:80), MP of silage and their interactions. After slaughter, hot carcass weight (HCW), pH, temperature, backfat thickness (BFT), and ribeye area (REA), yields of meat cuts (tenderloin, striploin, ribeye steak, neck steak, and sirloin cap), meat quality traits and economic analysis were evaluated. A lower final pH was found in the carcasses of animals consuming diets containing MP versus unprocessed silage (pH = 5.81 versus 5.93). Carcass variables (HCW, BFT, and REA) and meat cut yields were not affected by treatments. The C:R 20:80 increased the intramuscular fat (IMF) content by approximately 1%, without affecting moisture, ash, and protein contents. Meat/fat color (L*, a* and b*) and Warner-Bratzler shear force (WBSF) were similar among treatments. The results indicated that the MP of corn silage in finishing diets can provide better carcass pH results in Nellore bulls, without negatively influencing carcass weight, fatness, and meat tenderness (WBSF). The IMF content of meat was slightly improved using a C:R 20:80 and lower total costs per arroba produced (3.5%), daily costs per animal/day (4.2%), and cost per ton of feeds (5.15%) were found with MP silage.

Antioxidant, anti-inflammatory and anti-obesity effects of onion and its by-products in high-fat fed rodents: a systematic review.

The effects of onion and its by-products on metabolic changes induced by excessive consumption of a high fat diet have been the focus of many studies. The aim of this study was to systematically review the effects of onion and its by-products antioxidant, anti-inflammatory and anti-obesity in rats exposed to a high-fat diet. Five databases were used: Pubmed, EMBASE, Science Direct, Web of science and Scopus until June 2020 updated December 1, 2022. Research of the articles was carried out by two reviewers, searching and selecting studies after an initial reading of the titles and abstracts. In total, 2,448 papers were found and, after assessing against the inclusion and exclusion criteria, 18 papers were selected for this review. The findings of this review show the beneficial effects of onion and its by-products on inflammatory parameters, obesity, cardiovascular disease, thermogenesis and hepatic alterations generally associated with the consumption of a high-fat diet.

Contextual and individual determinants of tooth loss in the Afro-descendant older adult populations of different countries: a scoping review.

BACKGROUND: The Black population has poorer oral health than other racial groups; however, little is known about the mechanisms that explain this difference. OBJECTIVE: To study the association between race and tooth loss and map the evidence on factors associated with tooth loss in Black older populations. METHODS: Scoping review following the PRISMA Extension for Scoping Reviews conducted according to the recommendations of the Joanna Briggs Institute. A three-step search strategy was applied, and data were collected between April and July 2021. Searches were performed in the PubMed, Lilacs, and SciELO databases. The grey literature was searched using Google Scholar (https://www.scholar.google.com/). The reference lists of included studies were used as additional sources. Studies published in English and Portuguese of the association between tooth loss and different racial groups and the factors associated with tooth loss and tooth retention in Black older adult populations were included. RESULTS: Twenty-one of 913 original articles published between 1995 and 2020 were included. Of these, 75% were research articles, 15% were reports, and 10% dissertations. Eighty per cent reported cross-sectional and 20% longitudinal data. African ancestry was associated with increased odds of tooth loss in older adult populations. Periodontal disease, female sex, and advanced age were the exposures most frequently associated with tooth loss. CONCLUSION: Race, educational level, advanced age, and oral diseases such as periodontitis are associated with increased tooth loss in Afro-descendant older populations.

Antioxidant, anti-inflammatory and anti-obesity effects of onion and its by-products in high-fat fed rodents: a systematic review / Efeitos antioxidantes, anti-inflamatórios e anti-obesidade da cebola e seus subprodutos em roedores alimentados com alto teor de gordura: uma revisão sistemática

The effects of onion and its by-products on metabolic changes induced by excessive consumption of a high fat diet have been the focus of many studies. The aim of this study was to systematically review the effects of onion and its by-products antioxidant, anti-inflammatory and anti-obesity in rats exposed to a high-fat diet. Five databases were used: Pubmed, EMBASE, Science Direct, Web of science and Scopus until June 2020 updated December 1, 2022. Research of the articles was carried out by two reviewers, searching and selecting studies after an initial reading of the titles and abstracts. In total, 2,448 papers were found and, after assessing against the inclusion and exclusion criteria, 18 papers were selected for this review. The findings of this review show the beneficial effects of onion and its by-products on inflammatory parameters, obesity, cardiovascular disease, thermogenesis and hepatic alterations generally associated with the consumption of a high-fat diet.

Os efeitos da cebola e seus subprodutos nas alterações metabólicas induzidas pelo consumo excessivo de uma dieta rica em gordura têm sido foco de muitos estudos. O objetivo deste estudo foi revisar sistematicamente os efeitos da cebola e seus subprodutos antioxidantes, anti-inflamatórios e anti-obesidade em ratos expostos a uma dieta hiperlipídica. Foram utilizadas cinco bases de dados: Pubmed, EMBASE, Science Direct, Web of science e Scopus até junho de 2020, atualizado em 01 de dezembro de 2022. A pesquisa dos artigos foi realizada por dois revisores, buscando e selecionando os estudos após leitura inicial dos títulos e resumos. No total, 2.448 artigos foram encontrados e, após avaliação de acordo com os critérios de inclusão e exclusão, 18 artigos foram selecionados para esta revisão. Os achados desta revisão mostram os efeitos benéficos da cebola e seus subprodutos sobre parâmetros inflamatórios, obesidade, doenças cardiovasculares, termogênese e alterações hepáticas geralmente associadas ao consumo de uma dieta hiperlipídica.

In vitro fertilization: an unexpected finding in a cohort of patients with biliary atresia

In biliary atresia (BA), efforts to prevent premature liver transplantation (LT) are aimed at early diagnosis, timing of Kasai-portoenterostomy (KPE), and centralization of care. This report presents the clinical picture, treatment strategies, and outcomes of BA patients with no previous treatment. A retrospective cohort study (Jan/2001 to Jan/2021) was conducted to evaluate the outcome of patients with BA referred to a single team. Study groups were: 1) Kasai-only group (K-only) n=9), 2) LT-only group (n=7), and 3) Kasai+LT group (K+LT) (n=23). Survival with native liver and overall survival were 22.9 and 94.8%, respectively, at 120 months of follow-up. There was no difference in age at KPE in the K-only group (46.8±21.8 days) vs K+LT (52.1±22 days), P=0.4. Ten (25.6%) patients were babies conceived through in vitro fertilization (IVF). Four IVF patients (40%) presented associated congenital heart disease vs 5 patients (17%) in the remaining group (P=0.14). Two of the IVF patients were premature (<37 weeks). Median maternal age at birth was 35 years (33 to 41 years). Excellent patient survival is expected for patients with BA with the available treatment strategies. IVF+BA was an unexpected prevalent association in this cohort, and further studies are required to better understand these findings.

Influence of Manganese Oxide on the Esthetic Efficacy and Toxicity Caused by Conventional In-office Tooth Bleaching Therapy.

OBJECTIVE: This study aimed to evaluate the esthetic efficacy, cytotoxicity, and kinetics of decomposition of hydrogen peroxide (H2O2) present in a commercial bleaching gel with 35% H2O2 (BG35%) chemically activated with manganese oxide (MnO2). METHODS AND MATERIALS: After incorporating 2 mg/mL, 6 mg/mL, and 10 mg/mL of MnO2 into BG35%, the stability of pH and temperature of the products were analyzed. To assess the esthetic efficacy (ΔE and ΔWI), the BG35%s with MnO2 were applied for 45 minutes on enamel/dentin discs (DiE/D). BG35% or no treatment were used as positive (PC) and negative (NC) controls, respectively. To analyze the cell viability (CV) and oxidative stress (OXS), the same bleaching protocols were performed on DiE/D adapted to artificial pulp chambers. The extracts (culture medium + gel components that diffused through the discs) were applied to pulp cells and submitted to H2O2 quantification. BG35% with MnO2 that showed the best results was evaluated relative to kinetic decomposition of H2O2, with consequent generation of free radicals (FR) and hydroxyl radicals (OH•). The data were submitted to the one-way analysis of variance complemented by Tukey post-test (α=0.05). Data on kinetics of H2O2 decomposition were submitted to the Student's-t test (α=0.05). RESULTS: All the BG35%s with MnO2 showed stability of pH and temperature, and the gel with 10 mg/mL of this activator had an esthetic efficacy 31% higher than that of the PC (p<0.05). Reduction in OXS and trans-amelodentinal diffusion of H2O2 occurred when all the BG35%s with MnO2 were used. The addition of 6 and 10 mg/mL of MnO2 to BG35% increased the CV in comparison with PC, confirmed by the cell morphology analysis. An increase in FR and OH• formation was observed when 10 mg/mL of MnO2 was added to BG35%. CONCLUSION: Catalysis of BG35% with MnO2 minimized the trans-amelodentinal diffusion of H2O2 and toxicity of the product to pulp cells. BG35% containing 10 mg/mL of MnO2 potentiated the decomposition of H2O2, enhancing the generation of FR and OH•, as well as the efficacy of the in-office tooth therapy.

Use of blood residue as alternative source of phosphorus in sunflower (Helianthus annuus L. ) cultivation / [Utilização de resíduo de sangue como fonte alternativa de fósforo no cultivo de girassol (Helianthus annuus L. )]

The aim of this work was to increase the aerial part, biometry, and yield of achenes from sunflower plants on the effect of increasing doses of blood residue, as an alternative source of phosphorus (P), in a clayey-textured red Oxisol. The experimental design used was randomized blocks, with six treatments and four replications. The treatments consisted of five doses of blood residue (0, 6, 12, 24 and 48m3 ha-1) and a control treatment that received phosphate chemical fertilization, 80kg ha-1 of P2O5. The increasing doses of blood residue and chemical fertilization do not show disproportionality for P concentration in soil, leaf, plant height (PH), stem diameter (SD), chapter diameter (CD) and achene production. The analysis of the principal component (PC) revealed that the first PC presents the greatest accumulated variation (74%). Based on the first PC, the dose of 12m-3 ha-1 has greater influence for PH, SC, and CD. Due to the greater influence on the biometric characteristics of sunflower plants, the blood residue (12m-3 ha-1 = 98.4kg P ha-1), can be used as an alternative source of phosphorus for the cultivation of sunflower in clayey oxisols.

Objetivou-se com este trabalho verificar biometria de parte aérea, rendimento de aquênios de plantas de girassol sobre o efeito de doses crescentes de resíduo de sangue, como fonte alternativa de fósforo (P), em um Latossolo vermelho de textura argilosa. O delineamento experimento utilizado foi o de blocos casualizados, com seis tratamentos e quatro repetições. Os tratamentos foram constituídos por cinco doses de resíduo de sangue (0, 6, 12, 24 e 48m3 ha-1) e um tratamento que recebeu a adubação fosfatada química, 80kg ha-1 de P2O5. As doses crescentes de resíduo de sangue e adubação química não demostram desproporcionalidade para a concentração de P no solo, folha, altura de planta (AP), diâmetro de caule (DC), diâmetro de capítulo (DCP) e produção de aquênios. A análise de componentes (CP) principais revelou que o primeiro CP apresenta maior variação acumulada (74%). Baseado no primeiro CP, a dose de 12 m-3 ha-1exibe maior influência para AP, DC e DCP. Devido a maior influência sobre as características biométricas em plantas de girassol, o resíduo de sangue (12m-3 ha-1 = 98,4kg P ha-1), pode ser utilizado como fonte alternativa de fósforo para o cultivo de girassol em Latossolos de textura argilosa.

Colitis caused by Clostridioides difficile infection in a domestic dog: A case report.

Clostridioides difficile has been identified as one of the primary etiologic agents of nosocomial diarrhea and pseudomembranous colitis in humans and other mammals associated following broad-spectrum antibiotics use. In Rio de Janeiro, Brazil we describe a case of C. difficile infection (CDI) in a 13-year-old male dog.

Effect of Time and Temperature of Air Jet on the Mechanical and Biological Behavior of a Universal Adhesive System.

OBJECTIVES: To evaluate the influence of heat application on the degree of conversion (DC) of the 3M Single Bond Universal Adhesive System, as well as its transdentinal cytotoxicity and microtensile bond strength to dentin. METHODS: Experimental groups were established according to the time and temperature of the air jet: G1: 5 seconds-25°C; G2: 10 seconds-25°C; G3: 20 seconds-25°C; G4: 5 seconds-50°C; G5: 10 seconds-50°C; G6: 20 seconds-50°C. In control group (G7), no treatment was performed. The DC was assessed using the Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) technique. For the transdentinal cytotoxicity test, dentin discs fitted in artificial pulp chambers (APC) received the application of the adhesive system and the air jets. For the microtensile bond strength, healthy molars were restored and submitted to the microtensile test after 24 hours and 6 months, respectively. RESULTS: Significant reduction in viability of Mouse Dental Papilla Cell-23 (MDPC-23), which exhibited morphological changes, was observed in all experimental groups compared to control (p<0.05). Although all tested protocols resulted in transdentinal diffusion of 2-hydroxyethyl methacrylate (HEMA), the group G6 presented the highest degree of monomeric conversion and the lowest cytotoxic effect, with higher dentin bond strength values in comparison to group G1 (p<0.05). CONCLUSIONS: Applying an air blast at 50°C for 20 seconds increases the DC and microtensile bond strength of the 3M Single Bond Universal Adhesive System to dentin, as well as reduces the transdentinal cytotoxicity of the material to pulp cells.