Vital and Non-vital Posterior Teeth Restored With Onlays and Single Crowns Using Three Different Restorative Materials.

Inclusion Criteria: * • Subjects with the need for a fixed reconstruction in premolar and molar region with indication for either crown or onlay. * min. 18 years of age and ≤ 80 years * Patient with physical status PS1 and PS2 (according to Physical Status Classification System of the American Society of Anesthesiologists; Attachment 5) * Capable of providing written informed consent * Absence of any active periodontal and pulpal disease Exclusion Criteria: * Presence of conditions requiring chronic routine prophylactic use of antibiotics or prolonged use of steroids e.g. history of rheumatic heart disease, bacterial endocarditis, cardiac vascular anomalies, prosthetic joint replacements, etc. * Patients with history of renal failure, bleeding disorders, metabolic bone disorder, uncontrolled endocrine disorders, HIV infection, Hepatitis * History of neoplastic disease requiring the use of radiation or chemotherapy * Inability to perform adequate oral hygiene * Significant reduced saliva flow rate * Unable or unwilling to cooperate for the trial period * Allergy to any components of the reconstruction materials and cements * Alcohol or drug abuse * Pregnant or lactating women Specific criteria: * Root caries / root canal caries * Extreme short dental arch (eSDA) * Severe bruxism or clenching habits