Comparison of the strengths of aluminous porcelain fired on to platinum and palladium foils.

The disc strengths of aluminous porcelain fired on to both platinum and palladium foil matrices have been determined. Also, the effect on strength of removing the matrices has been measured. The appearance of the separated metal and porcelain surfaces has been studied using scanning electron microscopy, and energy dispersive X-ray analysis has been used to evaluate the chemical composition of these surfaces. Reasons for the increase in strength observed when the matrix is left intact are discussed. Practical suggestions for obtaining stronger jacket crowns are presented.