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Thermocycling effect on microhardness of laboratory composite resins
Pereira, Sarina Maciel Braga; Castilho, Anderson Almeid; Salazar-Marocho, Susana María; Oliveira, Karla Mychellyne Costa; Váquez, Vanessa Zulema Ccahuana & Bottino, Marco Antonio
Abstract
The aim of this study was to evaluate the thermocycling effect on
microhardness of laboratory composite resins. 30 disks were
fabricated, 5 mm of diameter and 2mm of width, using 3 laboratory
resins: G1 (n=10) - RESILAB MASTER (Wilcos-Brasil), G2 (n=10)
- Vita VMLC (VITA Zahnfabrik-Germany), and G3 (n=10) - Vita
Zeta (VITA Zahnfabrik-Germany). Vickers microhardness (HV) of
all specimens was evaluated using a microhardness tester FM-700
(Future Tech- 50 g/10s). The specimens were measured before and
after the thermocycling (3.000 times and 12.000 times - 5° /55°C±1).
The microhardness values before cycling were (mean±SD): G1:
55.50±4.6; G2: 35.54±2.5; G3: 27.97±1.6.; after 3.000 thermocycles:
G1: 55.54±3,9; G2: 29.92±2,73; G3:21.01±1.4 and after 12.000 cycles
G1:54.27±3.2; G2: 30.91±1.6. G3: 23.81±0.9. Variance analysis
(ANOVA) and Tukey's test was accomplished (p<0,05), the highest
microhardness values were observed in G1; G2 and G3 showed
reduction of microhardness values. It was concluded that, after
thermocycling, the tested laboratory composites resins are susceptible
to the decrease of surface microhardness.
Keywords
composite resins, microhardness, thermocycling
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