Physical and mechanical properties of pressure-molded and injection-molded denture base acrylics in different conditions

Cobalt-chromium alloys are commonly used for surgical implants because of their high strength, superior corrosion resistance, non-magnetic behavior, and biocompatibility. Cobalt-Chromium-Molybdenum (Co-Cr-Mo) applications include prosthetic replacements of hips. This paper presents the attempt to produce metallic implant using Co-Cr-Mo powder by MIM process, focusing on the effects of different heating rate during sintering process at 1380°C. Co-Cr-Mo powder were mixed homogeneously with palm oil and conventional binders respectively with powder loading 65 vol% and was injection molded using vertical injection molding machine with the nozzle temperature of 160°C to produce green compacts. The binders then was removed by solvent extraction process and sintered in vacuum condition at atmosphere 10-5 mbar at temperature 1380 °C with varied heating rate; 0.5°C/min, 1.0°C/min and 3.0°C/min . Results indicated that sintered density and tensile strength varied from 8.100 gcm-3 to 8.200 gcm-3 and 546.971 MPa to 798.767 MPa respectively. The mechanical properties comply with the international standard (ASTM F75).

Download Full-text

Effect of repeated disinfections by microwave energy on the physical and mechanical properties of denture base acrylic resins

Brazilian Dental Journal ◽

10.1590/s0103-64402009000200008 ◽

2009 ◽

Vol 20 (2) ◽

pp. 132-137 ◽

Cited By ~ 9

Author(s):

Rafael Leonardo Xediek Consani ◽

Douglas Duenhas de Azevedo ◽

Marcelo Ferraz Mesquita ◽

Wilson Batista Mendes ◽

Paulo César Saquy

Keyword(s):

Mechanical Properties ◽

Impact Strength ◽

Flexural Strength ◽

Physical And Mechanical Properties ◽

Knoop Hardness ◽

Microwave Energy ◽

Bending Test ◽

Denture Base ◽

Acrylic Resins ◽

The Impact

The present study evaluated the effect of repeated simulated microwave disinfection on physical and mechanical properties of Clássico, Onda-Cryl and QC-20 denture base acrylic resins. Aluminum patterns were included in metallic or plastic flasks with dental stone following the traditional packing method. The powder/liquid mixing ratio was established according to the manufacturer's instructions. After water-bath polymerization at 74ºC for 9 h, boiling water for 20 min or microwave energy at 900 W for 10 min, the specimens were deflasked after flask cooling and finished. Each specimen was immersed in 150 mL of distilled water and underwent 5 disinfection cycles in a microwave oven set at 650 W for 3 min. Non-disinfected and disinfected specimens were subjected to the following tets: Knoop hardness test was performed with 25 g load for 10 s, impact strength test was done using the Charpy system with 40 kpcm, and 3-point bending test (flexural strength) was performed at a crosshead speed of 0.5 mm/min until fracture. Data were analyzed statistically by ANOVA and Tukey's test (α= 0.05%). Repeated simulated microwave disinfections decreased the Knoop hardness of Clássico and Onda-Cryl resins and had no effect on the impact strength of QC-20. The flexural strength was similar for all tested resins.

Download Full-text