[A PhD completed. Scientific insights into restoring teeth with deep preparation outline]

Eliminating saliva or blood from contaminating adhesive treatments becomes increasingly challenging as the cavity size increases, especially when the preparation margin is located below the cementoenamel junction. A direct composite restoration can elevate this margin to a supragingival level, allowing for better isolation with a rubber dam. This process, known as deep margin elevation, enables dentists to more reliably bond partial restorations. This dissertation investigates how severely compromised teeth with deep preparation margins can best be restored, with a focus on the use of deep margin elevation in combination with partial indirect restorations. Through clinical and laboratory research, the survival, durability, and mechanical performance of these restorations are evaluated. The findings indicate that deep margin elevation is an effective technique, although there is still a lack of knowledge regarding long-term success rates, particularly concerning different restorative materials and the biological impact of deep preparation margins.