Stress distribution pattern on mandibular molar restored by occlusal veneer effect of veneer material and dental bonding surface

Abstract

It was aimed to evaluate the stress distribution within and around occlusal veneers that made from; lithium disilicate, zirconia and hybrid ceramic. Occlusal veneers to be bondedin three different ways (1) bonded directly to dentin, (2) bonded to dentin with prepared cavity and (3) bonded to dentin with composite filling as three case. Using nine freshly extracted mandibular first-molar were distributed into three equal groups according to the substrate. Where group I: lithium disilicate, group II: zirconia, group III: hybrid ceramic. Bonding all occlusal veneers to its corresponding prepared teeth was carried out by using "dual cure" adhesive resin cement. In addition, tree finite element models were prepared to to evaluate the distribution of stresses exerted in eachcase . 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. Under the average biting forces, all the tested occlusal veneers preparation designs showed values of stresses within the physiological limits.