BOND STRENGTH AND FAILURE MODE COMPARISON BETWEEN TWO ADHESIVE SYSTEMS FOR ORTHODONTICS

Objective: To compare the bond strength and failure mode between total and self-etching systems used for brackets cementation.Methods: Twenty human first premolars were randomly divided into two groups: 10 for the total etching system (Transbond™ XT, 3M Unitek, St. Paul, Minnesota, USA) and 10 for the self-etching system (Transbond™ Plus Self Etching Primer + Transbond™ XT, 3M Unitek, St. Paul, Minnesota, USA). Standard brackets (Ortho Organizers, California, USA) were cemented, and after 24 hours submitted to 5000 thermal cycles. Subsequently, shear bond strength tests were performed applying force at the bracket/enamel interphase using an universal testing machine (Instron®) at 1.5 mm/min crosshead speed. Finally, enamel surfaces and bracket bases were observed using a stereomicroscope (Stemi 2000C, Carl Zeiss, Göttingen, Germany).Results: The results, in terms of bond strength, showed a statistical significant difference (p<0.05) between the two adhesive systems, presenting higher values the total-etching system (28,98MPa vs. 18,67MPa). The predominant failure modes presented for both systems were at the adhesive-enamel interphase (80% and 70%).Conclusion: Bond strength and failure mode are influenced by the dental substrate pre-treatment and the chemical composition of the adhesive. Therefore, the in-vitro bond strength obtained when a self-etching system is used in orthodontics, produce enough micromechanical retention with lower risk of damage to the dental tissue.Objetivo: Comparar la fuerza adhesiva y el tipo de falla de dos sistemas adhesivos para ortodoncia.Materiales y métodos: Veinte primeros premolares superiores fueron divididos aleatoriamente en dos grupos: 10 para el grupo de grabado total (Transbond™XT, 3M Unitek, St. Paul, Minnesota, USA) y 10 para el grupo autograbador (Transbond™ Plus Self Etching Primer + Transbond™ XT, 3M Unitek, St. Paul, Minnesota, USA). A estos dientes se les cementaron brackets estándar (Ortho Organizers, California, USA) y después de 24 horas fueron sometidos a 5000 ciclos térmicos. Posteriormente se aplicó una fuerza de corte (velocidad 1.5mm/min) en la interfase bracket-esmalte en una máquina universal de ensayos (Instron™). Finalmente, las superficies del esmalte y las bases de los brackets se observaron mediante un estéreo-microscopio (Stemi 2000C, Carl Zeiss, Göttingen, Germany).Resultados: En fuerza adhesiva se observó una diferencia estadísticamente significativa (P<0.05) entre los dos sistemas, presentó mayor promedio el adhesivo de grabado total (28,98MPa vs. 18,67MPa). El tipo de falla predominante fue en la interfase adhesivo-esmalte (80% y 70% respectivamente).Conclusión: La fuerza adhesiva y el tipo de falla están influenciados por el pre-tratamiento del esmalte y la composición química del adhesivo. La fuerza adhesiva obtenida al utilizar un sistema autograbador en ortodoncia produce suficiente retención micro-mecánica con menor riesgo de lesionar el tejido dental.[Ciceri AL, Monroy JJ, Ardila G, Luna A, Rivera JR. Comparación de la fuerza adhesiva y el tipo de falla de dos sistemas adhesivos para ortodoncia. Ustasalud 2011; 10: 29 - 35

COVID-19 infection in adult patients with hematological malignancies: a European Hematology Association Survey (EPICOVIDEHA)

Background: Patients with hematological malignancies (HM) are at high risk of mortality from SARS-CoV-2 disease 2019 (COVID-19). A better understanding of risk factors for adverse outcomes may improve clinical management in these patients. We therefore studied baseline characteristics of HM patients developing COVID-19 and analyzed predictors of mortality. Methods: The survey was supported by the Scientifc Working Group Infection in Hematology of the European Hematology Association (EHA). Eligible for the analysis were adult patients with HM and laboratory-confrmed COVID19 observed between March and December 2020. Results: The study sample includes 3801 cases, represented by lymphoproliferative (mainly non- Hodgkin lymphoma n=1084, myeloma n=684 and chronic lymphoid leukemia n=474) and myeloproliferative malignancies (mainly acute myeloid leukemia n=497 and myelodysplastic syndromes n=279). Severe/critical COVID-19 was observed in 63.8% of patients (n=2425). Overall, 2778 (73.1%) of the patients were hospitalized, 689 (18.1%) of whom were admitted to intensive care units (ICUs). Overall, 1185 patients (31.2%) died. The primary cause of death was COVID19 in 688 patients (58.1%), HM in 173 patients (14.6%), and a combination of both COVID-19 and progressing HM in 155 patients (13.1%). Highest mortality was observed in acute myeloid leukemia (199/497, 40%) and myelodysplastic syndromes (118/279, 42.3%). The mortality rate signifcantly decreased between the frst COVID-19 wave (March–May 2020) and the second wave (October–December 2020) (581/1427, 40.7% vs. 439/1773, 24.8%, p value<0.0001). In the multivariable analysis, age, active malignancy, chronic cardiac disease, liver disease, renal impairment, smoking history, and ICU stay correlated with mortality. Acute myeloid leukemia was a higher mortality risk than lymphoproliferative diseases. Conclusions: This survey confrms that COVID-19 patients with HM are at high risk of lethal complications. However, improved COVID-19 prevention has reduced mortality despite an increase in the number of reported cases

Decoding the historical tale: COVID-19 impact on haematological malignancy patients—EPICOVIDEHA insights from 2020 to 2022

Background: The COVID-19 pandemic heightened risks for individuals with hematological malignancies due to compromised immune systems, leading to more severe outcomes and increased mortality. While interventions like vaccines, targeted antivirals, and monoclonal antibodies have been effective for the general population, their benefits for these patients may not be as pronounced. Methods: The EPICOVIDEHA registry (National Clinical Trials Identifier, NCT04733729) gathers COVID-19 data from hematological malignancy patients since the pandemic's start worldwide. It spans various global locations, allowing comprehensive analysis over the first three years (2020–2022). Findings: The EPICOVIDEHA registry collected data from January 2020 to December 2022, involving 8767 COVID-19 cases in hematological malignancy patients from 152 centers across 41 countries, with 42% being female. Over this period, there was a significant reduction in critical infections and an overall decrease in mortality from 29% to 4%. However, hospitalization, particularly in the ICU, remained associated with higher mortality rates. Factors contributing to increased mortality included age, multiple comorbidities, active malignancy at COVID-19 onset, pulmonary symptoms, and hospitalization. On the positive side, vaccination with one to two doses or three or more doses, as well as encountering COVID-19 in 2022, were associated with improved survival. Interpretation: Patients with hematological malignancies still face elevated risks, despite reductions in critical infections and overall mortality rates over time. Hospitalization, especially in ICUs, remains a significant concern. The study underscores the importance of vaccination and the timing of COVID-19 exposure in 2022 for enhanced survival in this patient group. Ongoing monitoring and targeted interventions are essential to support this vulnerable population, emphasizing the critical role of timely diagnosis and prompt treatment in preventing severe COVID-19 cases. Funding: Not applicable