EFFECT OF GLASS JOINS ON PERFORMANCE OF LAYERED DENTAL CERAMIC SYSTEMS

Abstract

Layered structures can be used to address the competing needs of systems like dental crown restorations where the exterior needs to be aesthetic and the interior needs to be strong and fatigue resistant. Dental crowns typically have an aesthetic porcelain veneer layered on a strong, fatigue resistant ceramic or metallic core. In current restorations, even when the core is shaped by a computer-aided design and manufacturing (CAD/CAM) or solid-freeform fabrication processes, the veneer is applied in sequential layers. This process is labor intensive, time consuming and may not optimize the long-term performance properties of the veneer layer. If the core and veneer layers were to be independently fabricated and then joined, their individual and the veneer-core system performance could be optimized. Some groups have explored the possibility of joining with filled epoxies, which is easier, but may not be long-lasting. In this project we explore the possibility of using more durable glassy joins. Dense, thermal-expansion-matched (to the core and veneer glass) joins can be fired at temperatures far enough below the melting and/or slumping temperatures to join veneers to cores without degradation. In this study, we design and fabricate joining glasses for bonding porcelain veneers to ceramic cores, specifically to dental aluminas and zirconias. We study the chemical bonding and mechanical integrity of the resulting layers. Finally, we assess the effects of glass joins on performance of layered dental ceramic systems.