A randomized controlled clinical trial, a double-blind (patient and examiner) is conducted by one trained and calibrated operators who perform all restorative procedures. The restorations are evaluated by a blind and calibrated two examiner using the FDI World Dental Federation criteria. A total of 24 patients will be randomly assigned to each group for a total of 48 patients. The randomization sequence will be generated (www.randomlists.com/team-generator) and to ensure the confidentiality of the allocation, this will be used opaque, sealed and numbered envelopes in series. These will be kept with an independent researcher for the moment of inclusion of the subjects.~Both groups will receive Onlay preparation . Digital impression by intra oral scanner will be taken, wax pattern for the onlay restoration will be designed and milled using CAD/CAM software. After that, the wax pattern will be invested and final onlay restoration will be constructed from VITA AMBRIA and IPS e.max press ingots according to manufacturing instructions. Primary outcome: The amount of wear will be evaluated according to FDI standard.
The 1ry objective will be to evaluate the amount of wear of onlays restorations made from VITA AMBRIA & IPS e.max Press and their opposing natural teeth.~2. The 2ry objective of the clinical trial will be to evaluate the fractures, retention, contact points, food impaction and radiographic examination of the VITA AMBRIA onlays compared with IPS e.max press onlays as defined by FDI criteria.