Influence of Preparation Design and Presence of Class IV Composite Resin Restoration on Fracture Resistance of Ceramic laminate Veneer


The objective of the study was to evaluate the fracture resistance of ceramic veneer bonded to class IV composite resin restoration using two differentincisal preparation designs.Twenty-eight extracted intact human maxillary incisors free from cracks and of equal dimensions were randomly divided into two main groups; G1 (control): intact teeth without class IV composite restoration, G2: teeth with class IV composite restorations. Each group was further divided according to the preparation design of the laminate veneers (n=7); A: incisal butt joint design and B: incisal overlap design. Class IV was prepared with obliqueincisal margin.Etching and bonding were performed and a nanohybrid composite resin was applied. Two veneer preparation designs were made; butt joint with shoulder finish line and incisal overlap with palatal chamfer. The impression were made usinga 3D-scanner. The veneers were fabricated with a heat pressed all ceramic material (IPS-Emax, IvoclarVivadent) according to manufacturer’s protocol.The internalveneer surface was etched with 5% hydrofluoric acid then silanated.Dual cure resin cement (Variolink N base and catalyst, IvoclarVivadent) wasused for cementation.Fracture resistance measurement was recorded using universal testing machine.The veneer incisal preparation design had a statistically significant effect on mean fracture resistance of PLVs whereas presence of class IV restoration had no statistically significant effect on mean fracture resistance.The incisal overlap design showed statistically significantly higher mean fracture resistance than the incisal butt joint design. The preparation design affected the fracture resistance of PLVs bonded to class IV composite restorations. Yet,the presence of class IV composite restorations did not affectthe fracture resistance of bonded PLVs. The incisal overlap design seemed to protect PLVs bonded to class IV restorations.