[Fracture analyses of casting framework removable partial dentures].

OBJECTIVE

To compare the clinical fracture rates of removable partial denture (RPD) made of titanium with that of Co-Cr alloy, to analyze the fracture modes and reasons of two kinds of metal frameworks, and to explore the effect of defects on the fracture process.

METHODS

Following totally 30 618 RPDs made by titanium and by Co-Cr alloy, the fracture rates in 18-month were calculated individually. The fractured surfaces of failed RPDs were examined by fractography investigations using a field emission scanning electron microscope to disclose the fracture mode and damage character. The energy-dispersive X-ray spectroscopy analysis was performed to examine the chemical compositions.

RESULTS

The fracture rate of titanium framework was 1.75%, comparing with 0.57% of Co-Cr alloy framework. The reasons included teeth preparing, framework design, and defects during casting. The fracture modes of titanium and Co-Cr alloy framework performed toughness fracture character. The fissures were found in both titanium and Co-Cr alloy frameworks, and pores were detected in titanium frameworks.

CONCLUSION

The higher fracture rate of titanium framework is related to the defects during casting.