Apparent density and tensile strength of materials for facially butted porcelain margins.

The study focused on comparison of the as-fired density and tensile strength of unmodified and modified porcelains used for construction of facially butted porcelain margins. The respective densities and tensile strengths of unmodified body and shoulder porcelains were found to be comparable. Also statistically equivalent were the measured properties of specimens made from either an unmodified shoulder-porcelain formulation or shoulder-porcelain powder--aqueous sodium silicate solution mixtures. On the other hand, the respective densities and tensile strengths of body porcelain-resin and shoulder porcelain-wax combinations were significantly lower (p less than 0.05) than those of their unmodified counterparts. Low density and tensile strength limit the rational use of wax or resin-modified porcelains to final bakes for correcting small, troublesome labiogingival discrepancies.