Examinando por Materia "Microhardness"

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Acceso abierto
Comparative analysis of surface microhardness of nanohybrid and bulk fill resins using two polishing systems. In vitro study. Lima, Peru 2021
(Universidad Privada Norbert Wiener, 2022-09-30) Nuñez Linares, Merly; Guevara Sotomayor, Juan César
Objective: To compare the surface microhardness of Nanohybrid and Bulk Fill resins using two polishing systems. In vitro study. Lima, Peru, 2021. Methodology: The dental resins Filtek Z350 XT and Filtek Bulk Fill were molded into discs with a height of 5 mm and a diameter of 4 mm, using increments of 2 mm for Filtek Z350 XT and 4 mm for Filtek Bulk Fill. The resin discs were divided into two groups and polished using Sof-Lex discs and rubber cups. The sample size was determined through sample calculation, with 14 resin discs of each type, which were evaluated using a Vickers hardness machine (Durometer), producing indentations on the surface of the resin discs to determine the microhardness of each polished resin. Data were processed using SPSS software and the Student's t-test was applied for statistical analysis. Results: The surface microhardness of the Nanohybrid resin, Filtek Z350 XT, using the Sof-Lex disc polishing system was 67.81 ± 1.93 Hv, while using the rubber cup polishing system, it was 69.16 ± 3.57 Hv. The surface microhardness of the Bulk Fill resin, Filtek Bulk Fill, using the Sof-Lex disc polishing system was 51.59 ± 3.75 Hv, while using the rubber cup polishing system, it was 50.68 ± 1.90 Hv.
Acceso abierto
Effect of three beverages on the micro-strength of a composite resin: in vitro study
(Universidad Privada Norbert Wiener, 2019-08-15) Gómez Vásquez, Katty; Vilchez Bellido, Dina
The objective of this research was to compare the effect of three beverages on the microhardness of a composite resin in an in vitro study. The study was experimental, longitudinal, comparative, and prospective, with a comparative level, consisting of a sample of 10 composite resin discs per group, which were immersed in four immersion liquids, totaling 40 (n=40). The beverages used were an energy drink (Volt), a carbonated drink (Guaraná), a hydration drink (Gatorade), and as a control group, physiological serum. The results showed that the composite resin subjected to the energy drink Volt had an initial microhardness of 76.27 ± 4.74 Kg/mm² and a final microhardness of 70.04 ± 3.92 Kg/mm²; the composite resin subjected to the carbonated drink Guaraná had an initial microhardness of 77.04 ± 2.69 Kg/mm² and a final microhardness of 73.32 ± 3.59 Kg/mm²; the composite resin subjected to the hydration drink Gatorade had an initial microhardness of 78.48 ± 5.33 Kg/mm² and a final microhardness of 70.96 ± 2.18 Kg/mm²; while the composite resin subjected to physiological serum had an initial microhardness of 80.06 ± 3.48 Kg/mm² and a final microhardness of 70.15 ± 2.60 Kg/mm². A statistically significant difference was found between the initial and final microhardness of the composite resin subjected to the energy drink Volt, hydration drink Gatorade, and carbonated drink Guaraná (p<0.05). Conclusion: A variation between the initial and final microhardness of the composite resin was observed when subjected to the different beverages studied.
Acceso abierto
Erosive effect of three types of peruvian industrialized regional beverages on bovine dental enamel. In vitro study
(Universidad Privada Norbert Wiener, 2024-08-16) Rojas Huillca, Pamela Zadith; Aguirre Morales, Anita Kori
This thesis aimed to compare the erosive effect of three types of industrialized regional Peruvian drinks on bovine enamel in an in vitro study. This study was conducted using a quantitative, experimental, descriptive, and cross-sectional design; applied to a convenience sample of 100 healthy bovine lower incisors. Two instruments were used to collect information on pH levels and the erosive effect on bovine enamel, validated by expert judgment. The technique used for the in vitro test was the Vickers microhardness test, which was carried out at the National University of Engineering, Faculty of Mechanics. The results demonstrated a greater erosive effect during the exposure interval, where it was found that in the 24-48 hour exposure interval, the Lorenza® Chicha de Jora drink presented the greatest erosive effect, as the samples showed a lower measurement of bovine enamel microhardness at 29.19 HV (value 2) (see Table 1). The Selva® purple corn drink showed the least erosive effect in this time interval, as the exposed samples showed an average microhardness of 67.76 HV (value 2) (see Table 1). In the global averages, the Camu Camu La Florencia® drink stood out with values of 232.16 HV (value 4) (see Table 2), while the Selva® purple corn drink in the global averages obtained a microhardness of 208.65 HV (value 4) (see Table 2). Conclusion: The results of the Vickers microhardness test demonstrated the erosive effect of Peruvian industrialized beverages on bovine enamel. The greatest erosive effect occurred with the Camu Camu La Florencia® drink in the 48-72 hour exposure time, with values of 18.78 HV (value 3) (see Table 1).