Effects of LED Lights on Bulk Fill Resin Polymerization

The present study analyzed the microhardness and degree of conversion of three Bulk Fill resins (M1 - Filtek Bulk Fill; M2 - Tetric N-Ceram Bulk Fill and M3 - Opus Bulk Fill) polymerized by single peak and polywave Light-emitting Diode Curing Lights. A total 90 test specimens (n=10) were obtained using a Teflon matrix for the purpose of testing microhardness; and for degree of conversion: 135 specimens (n=5) by using a 2 x 6 cm matrix. The specimens were light polymerized using 3 light sources (L1 - Optilight Max, L2 - Bluephase, L3 - VALO). They were kept in artificial saliva om an oven at 37±1°C during the experiment. The degree of conversion was measured by FTIR 24 h after obtaining each test specimen. The microhardness readouts were performed with a microdurometer at the time intervals of 48 hours (T0), 7 days (T1), 14 days (T2) and 21 days (T3). M1L3 was found to show the highest microhardness values in T2, and M1 showed the lowest degree of conversion in the deep third with L1. It was concluded that Filtek Bulk Fill resin showed the best results in comparison with the other resins.

El presente estudio analizó la microdureza y el grado de conversión de tres resinas Bulk Fill (M1 - Filtek Bulk Fill; M2 - Tetric N-Ceram Bulk Fill y M3 - Opus Bulk Fill) polimerizadas por lámparas de curado de diodo emisor de luz de pico único y polionda. Se obtuvieron un total de 90 especímenes de prueba (n=10) utilizando una matriz de teflón con el propósito de probar la microdureza; y para grado de conversión: 135 especímenes (n=5) utilizando una matriz de 2 x 6 cm. Las muestras se fotopolimerizaron utilizando 3 fuen- tes de luz (L1 - Optilight Max, L2 - Bluephase, L3 - VALO). Se mantuvieron en saliva artificial en estufa a 37 ±1°C durante el experimento. El grado de conversión se midió por FTIR 24 h después de obtener cada muestra de prueba. Las lecturas de microdureza se realizaron con un microdurómetro en los intervalos de tiempo de 48 horas (T0), 7 días (T1), 14 días (T2) y 21 días (T3). Se encontró que M1L3 mostraba los valores más altos de microdureza en T2, y M1 mostraba el grado más bajo de conversión en el tercio profundo con L1. Se concluyó que la resina Filtek Bulk Fill mostró los mejores resultados en comparación con las demás resinas.

Underwater versus conventional EMR of large nonpedunculated colorectal lesions: a multicenter randomized controlled trial.

BACKGROUND AND AIMS: Underwater EMR (UEMR) is an alternative procedure to conventional EMR (CEMR) to treat large, nonpedunculated colorectal lesions (LNPCLs). In this multicenter, randomized controlled clinical trial, we aimed to compare the efficacy and safety of UEMR versus CEMR on LNPCLs. METHODS: We conducted a multicenter, randomized controlled clinical trial from February 2018 to February 2020 in 11 hospitals in Spain. A total of 298 patients (311 lesions) were randomized to the UEMR (n = 149) and CEMR (n = 162) groups. The main outcome was the lesion recurrence rate in at least 1 follow-up colonoscopy. Secondary outcomes included technical aspects, en bloc resection rate, R0 resection rates, and adverse events, among others. RESULTS: There were no differences in the overall recurrence rate (9.5% UEMR vs 11.7% CEMR; absolute risk difference, -2.2%; 95% CI, -9.4 to 4.9). However, considering polyp sizes between 20 and 30 mm, the recurrence rate was lower for UEMR (3.4% UEMR vs 13.1% CEMR; absolute risk difference, -9.7%; 95% CI, -19.4 to 0). The R0 resection showed the same tendency, with significant differences favoring UEMR only for polyps between 20 and 30 mm. Overall, UEMR was faster and easier to perform than CEMR. Importantly, the techniques were equally safe. CONCLUSIONS: UEMR is a valid alternative to CEMR for treating LNPCLs and could be considered the first option of treatment for lesions between 20 and 30 mm due to its higher en bloc and R0 resection rates. (Clinical trial registration number: NCT03567746.).

Changes in the properties of bulk-fill resins under conditions of gastroesophageal reflux and bulimia

Aim: Evaluate the roughness, microhardness and color change of different Bulk Fill resins when submitted to the condition of gastroesophageal reflux and bulimia. Methods: 60 specimens (n = 10) of Bulk-Fill composite resins were made: M1 ­ Filtek™; M2 ­ Tetric N-Ceram and M3 ­ OPUS, through a matrix 2x6 mm and light cured by the VALO light source. After polishing, initial analyzes (48 hours - T0) of surface roughness (Ra), microhardness (VHN) and color change (ΔE) were performed. To simulate the oral condition of severe gastroesophageal reflux and bulimia, the specimens were immersed in hydrochloric acid (S1) (pH 1.7) 4 minutes a day, for 7 days. Control group specimens were immersed in artificial saliva (S2). Subsequently to immersions, mechanical brushing was performed for 3 minutes, three times a day, simulating 7 days of brushing. And again, the analyzes of Ra, VHN and ΔE were performed (7 days - T1). Thus, hydrochloric acid immersion, mechanical brushing and Ra analysis were repeated at 14 days (T2) and 21 days (T3); and T2, T3 and T4 (3 years) for VHN and ΔE. Results: After Shapiro-Wilk statistical test, ANOVA and Tukey test with Bonferroni adjustment (p>0.05), M3 showed the lowest Ra at all times compared to the other resins, while the highest Ra was at T0. M1 and T1 showed higher VHN. And M2 and T4 showed higher ΔE. Conclusion: Bulk Fill resins can be indicated for patients with Gastroesophageal Reflux and Bulimia, nonetheless, Tetric N-Ceram resin showed the worst results

Effect of Color and Surface Roughness of Glass Ionomer Cements Submitted to Solutions Based on Ilex paraguariensis

ABSTRACT: The present study analyzed the color change (DE) and surface roughness (Ra) of glass ionomer cements (GICs) subjected to typical herbaceous South American beverage action - Ilex paraguariensis. 90 specimens (n = 10) were made: M1 - GIC Riva Light Cure® (SDI); M2 - GIC Riva Self Cure® (SDI); M3 - GIC Vitremer® (3M ESPE). After light curing/ polymerization of GICs, specimens were divided for being submitted to solutions for one hour a day for 21 days: S1 - Yerba Mate Pajarito Traditional (Pajarito); S2 - Erva Mate Chimarrão (Barão de Cotegipe); S3 - Water (control). Four DE and Ra readings were taken: T0 - initial; T1 - 7 days; T2 - 14 days and T3 - 21 days, with a spectrophotometer and a roughness meter respectively. The obtained data were submitted to ANOVA statistical analysis and Bonferroni. S1 and S2 at T1 and T2 there was no statistical difference between the materials, and at T3 Materials M1=M2, M1=M3, and M2>M3. For S3 at T1, T2 and T3 there was no difference between the materials. Analyzing surface roughness, there was no statistical significance. Concluded that all materials changed color with greater influence of time, but without changing surface roughness.

RESUMEN: En el presente estudio se analizó el cambio de color (DE) y la rugosidad superficial (Ra) de los cementos ionómero de vidrio (CIV) sometidos a la acción típica de las bebidas herbáceas sudamericanas - Ilex paraguariensis. Se realizaron 90 especímenes (n = 10): M1 - GIC Riva Light Cure® (SDI); M2 - GIC Riva Self Cure® (SDI); M3 - GIC Vitremer® (3M ESPE). Después de la fotopolimerización/ polimerización de los CIV, los especímenes se dividieron y fueron sometidos a soluciones durante una hora al día durante 21 días: S1 - Yerba Mate Pajarito Tradicional (Pajarito); S2 - Erva Mate Chimarrão (Barão de Cotegipe); S3 - Agua (control). Se tomaron cuatro lecturas de DE y Ra: T0 - inicial; T1 - 7 días; T2 - 14 días y T3 - 21 días, con espectrofotómetro y rugosímetro respectivamente. Los datos obtenidos fueron sometidos a análisis estadístico ANOVA y Bonferroni. S1 y S2 en T1 y T2 no hubo diferencia estadística entre los materiales y en T3 Materiales M1=M2, M1=M3 y M2>M3. Para S3 en T1, T2 y T3 no hubo diferencia entre los materiales. Al analizar la rugosidad de la superficie, no hubo significación estadística. En conclusion, todos los materiales cambiaron de color con mayor influencia del tiempo, pero sin cambiar la rugosidad de la superficie.

Microhardness and surface roughness of Biodentine exposed to mouthwashes.

Aim: This study evaluates Vickers microhardness and surface roughness in Biodentine cement (M1) and glass-ionomer cement Fuji IX (M2), both immersed in mouthwash. Materials and Methods: Fifty-four samples were randomly distributed in distilled water (S1), Listerine Cool Mint (S2), and Colgate Plax (S3). Each sample was put in a flask with mouthwash for 2 min, under vibration, twice a day for 21 days. Microhardness and surface roughness were assessed at 48 h (T0), 7 days (T1), 14 days (T2), and 21 days (T3). Results: For roughness: time (T), solution (S) and material (M), TxM, and SxM and for microhardness: M, TxS, TxM, and SxM were statistically significant. T3, M1, M1T3, and M1S1 presented the highest surface roughness. M2, M1T0, M1T1, M1T2, M1S1, and M1S2 presented higher microhardness. Conclusion: Biodentine showed higher surface roughness for T1, T2, and T3 and higher microhardness for T0, T1, and T2 against Fuji IX. Biodentine presented higher microhardness independently of solution.