IADR Abstract Archives
Evaluation of the mechanical, metallurgical and fractural properties of soldered DMLS metal frameworks.
Objectives: The aim of this study was to compare the mechanical and metallurgical properties of direct metal laser sintered (DMLS) soldering vs. conventional soldering conducted on both DMLS and conventionally cast metal frameworks.
Methods: Two groups of 3 unit CoCr metal frameworks including 1st-premolar, 2nd-premolar and 1st-molar were prepared using DMLS (n=45) and conventional casting (n=45) methods. Specimens in each manufacturing method were further divided in 3 subgroups (n=15); DMLS soldered, conventionally soldered and non-soldered control-groups. Specimens in soldered groups were separated between 1st and 2nd premolars. The size of the separation-gap was standardized as 2mm×3mm. Three-point-bending tests were carried out on stainless-steel molds. 2-way-ANOVA followed by Tukey-HSD test (α=0.05) was used for statistical analysis. Fracture surface of metal frameworks were evaluated using optical and scanning electron microscopes (SEM).
Results: The mean fracture strength of the conventionally-soldered group (1334.3±547.1MPa) was higher than that of DMLS-soldered group (881.7±572.8 MPa), but there was no statistically significant difference (p>0.05) between the 2 groups. The mean fracture strength of both DMLS (19330.6±2405.7MPa) and conventionally-cast (4268.5±1506.1MPa) control groups were statistically significantly higher than the soldered groups (p<0.05). A statistically significant difference was found between the control groups as well (p<0.05). Optical microscope and varying magnifications of SEM images were in accordance with the mechanical properties. Soldered surfaces were observed only on the peripheral of the fracture surface where no integration was observed on the center yielding decreased fracture strength in the soldered groups.
Conclusions: Both DMLS and conventional soldering methods decrease the fracture strength of metal frameworks. Soldering of metal frameworks should be avoided.
Methods: Two groups of 3 unit CoCr metal frameworks including 1st-premolar, 2nd-premolar and 1st-molar were prepared using DMLS (n=45) and conventional casting (n=45) methods. Specimens in each manufacturing method were further divided in 3 subgroups (n=15); DMLS soldered, conventionally soldered and non-soldered control-groups. Specimens in soldered groups were separated between 1st and 2nd premolars. The size of the separation-gap was standardized as 2mm×3mm. Three-point-bending tests were carried out on stainless-steel molds. 2-way-ANOVA followed by Tukey-HSD test (α=0.05) was used for statistical analysis. Fracture surface of metal frameworks were evaluated using optical and scanning electron microscopes (SEM).
Results: The mean fracture strength of the conventionally-soldered group (1334.3±547.1MPa) was higher than that of DMLS-soldered group (881.7±572.8 MPa), but there was no statistically significant difference (p>0.05) between the 2 groups. The mean fracture strength of both DMLS (19330.6±2405.7MPa) and conventionally-cast (4268.5±1506.1MPa) control groups were statistically significantly higher than the soldered groups (p<0.05). A statistically significant difference was found between the control groups as well (p<0.05). Optical microscope and varying magnifications of SEM images were in accordance with the mechanical properties. Soldered surfaces were observed only on the peripheral of the fracture surface where no integration was observed on the center yielding decreased fracture strength in the soldered groups.
Conclusions: Both DMLS and conventional soldering methods decrease the fracture strength of metal frameworks. Soldering of metal frameworks should be avoided.