Marginal fit and fracture resistance of CAD/CAM glass ceramic occlusal veneers with different preparation designs.

BACKGROUND

To assess marginal fit and fracture resistance of CAD/CAM glass ceramic occlusal veneers with different preparation designs.

METHODS

First premolar typodont maxillary was chosen. Standard IPS E.max CAD occlusal veneer preparations were carried out using Exocad software using three distinct designs: the first design involved a minimally invasive preparation (butt joint"BJ"group); the second design involved an occlusal veneer preparation with a circumferential hollow chamfer finish line"HC"group; and the third design involved a deep chamfer finish line"DC"group. To create a total of 24 epoxy resin replicas, each prepared design was reproduced eight times ("n = 8"for each prepared design). Every sample was made using IPS E.max CAD ceramics. Every occlusal veneer was firmly attached to the matching epoxy resin using adhesive resin cement. A computerized stereomicroscope was used to measure the vertical marginal gap. Ultimately, the fracture resistance was measured using a universal testing apparatus.

RESULTS

Deep chamfer occlusal veneer design, group"DC", registered statistically significant the highest mean value of vertical marginal gap (118.38 ± 10.43 μm) as well as the lowest mean value of failure load (549.97 ± 56.66 N). While butt joint occlusal veneer design"BJ"registered a statistically significant lowest mean value of vertical marginal gap (99.2 ± 7.15 μm) as well as the highest mean value of failure load (1107.25 ± 93.09 N).

CONCLUSIONS

Although different preparation designs of IPS E.max CAD occlusal veneer restorations would significantly affect the marginal fit and fracture resistance, all groups were within the clinically accepted range.