An intraindividual clinical comparison of 2 metal-ceramic systems

It has been questioned whether the surface and color of the ceramic and the metal-ceramic bond strength of a titanium-ceramic system are comparable to those of a conventional noble alloy-ceramic system. It was therefore the aim of this study to carry out an intraindividual clinical comparison between crowns fabricated according to the Procera system (titanium copings veneered with a low-fusing ceramic) and noble-alloy copings veneered with a medium-fusing ceramic.

Twenty-one crown pairs were fabricated for eighteen patients; three of the patients were each provided with two crown pairs. After 2 years nineteen crown pairs in sixteen patients could be compared. Clinical examinations were performed by two calibrated dentists who are long experienced in prosthetic dentistry. The crowns were rated according to the California Dental Association system. In addition, Bleeding Index and Margin Index were evaluated.

After 2 years the quality of surface and color of the ceramic material seemed to have deteriorated more in titanium-ceramic crowns than in conventional metal-ceramic crowns, although the difference was not statistically significant. Regarding anatomic form, margin integrity, Bleeding Index, and Margin Index the differences between the two crown systems were small.

The low-fusing ceramics have been subject to improvements during the last few years. Their bond strength to titanium seems to be comparable to that of conventional metal-ceramic systems. However, in the long run one problem may be the surface and color stability of low-fusing ceramics. To make extended long-term comparisons between the two metal-ceramic systems possible the present patient material will be followed for a longer period than the current 2 years.