The objective of this study was to compare the 5-year survival and clinical behavior of single posterior ceramic crowns made with pressable ceramic on zirconia or on a metal framework. If failures occurred, the further aim of the study was to delineate the factors contributing to the failure. The null hypothesis stated that the survival of zirconia-based restorations would be no worse that those made with metal-based material.

Inclusion Criteria:

• Informed Consent as documented by signature
• Male and female patients from 18-70 years of age
• Need for a single crown restoration
• Presence of antagonist
• minimum of 20 teeth
• moderate to good oral hygiene with the ability to perform mechanical oral hygiene techniques including tooth brushing
• low to moderate caries risk, and no active periodontal disease.

Exclusion Criteria:

• Women who are pregnant at the date of inclusion
• Known or suspected non-compliance, drug or alcohol abuse
• Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc. of the participant
• Smoking more than 15 cigarettes a day
• Poor oral hygiene (Plaque Index over 30%)
• Bruxism
• vital teeth
• allergic reaction or hypersensitivity to ingredients of the adhesive or restorative material