STRENGTH AND PHASE FORMATION OF DENTAL AMALGAM

¹ Department of Dental Materials, Marquette University School of Dentistry, Milwaukee, Wis.

A controlled specimen preparation is described which results in high reproducibility both in respect to physical properties and diffraction data.

The highest strength of dental amalgam was obtained by early condensation at high condensation load. Specimens produced in this manner showed x-ray diffraction evidence of a maximum of original alloy and a minimum of the silver-mercury and tin-mercury phases.

Strength of dental amalgam was reduced by delayed condensation particularly at low condensation load. These conditions also caused a reduction in the amount of original alloy present and an increased phase formation.

The quantitative distribution between the silver-mercury phase and the tin-mercury phase could not be related to variations in condensation load or trituration time.

From the normalized intensities it appears that decreased condensation load results in increased phase formation of both the silver-mercury and the tin-mercury phases per unit of original alloy. Also, delay in condensation has this effect, thus indicating that the completeness of the reaction is furthered by decreased condensation load, or by delayed condensation.