This study aimed to evaluate stress distribution within and around; lithium disilicate, zirconia and hybrid ceramic occlusal veneers. That bonded to dentin, dentin with prepared cavity and dentin with composite filling as three case.

Nine freshly extracted human mandibular first molars were distributed into three equal groups (n=3) according to the substrate; group I: lithium disilicate, group II: zirconia, group III: hybrid ceramic. A dual cure, adhesive resin cement was used to bond all occlusal veneers to corresponding prepared teeth. In addition, finite element analysis was carried out to evaluate the distribution of stresses.

Different occlusal veneers preparation designs showed minor differences appeared by changing restoration materials in each model. Under vertical loading zirconia occlusal veneer showed the lowest deformation followed by lithium disilicate occlusal veneer and hybrid ceramics occlusal veneer showed the highest deformations. Cement under zirconia restoration showed the lowest deformation followed by lithium disilicate and hybrid ceramics showed the highest deformations. The dentin for the model of dentin with composite filling subgroup showed the lowest stresses then the model of Dentin subgroup.

All the occlusal veneers preparation designs showed stress values within the safety factor when subjecting the models to the average biting force.