| 摘要 |
The radiopaque dental filling compositions based on liquid polymerisable organic resin binders and finely divided inert inorganic radiopaque filler particles essentially contain as the only X-ray-absorbing component of the radiopaque filler particles 3 to 10 % by weight of the total filler particles of thorium dioxide or tantalum pentoxide or a mixture of thorium dioxide and tantalum pentoxide. The filling compositions are insoluble and cannot be leached out in an aqueous medium, strongly absorb short-wavelength X-rays and have a low coefficient of thermal expansion, low toxicity, high mechanical strength and a transparency similar to that of dental enamel.
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