Relation between cavity design and marginal adaptation in a machine-milled ceramic restorative system

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Restorative Dentistry

Background:

• Optimizing marginal adaptation is crucial for the longevity and success of indirect ceramic restorations.
• Computer-aided design/computer-aided manufacturing (CAD/CAM) systems, such as Cerec 2, offer efficient fabrication of ceramic restorations.
• Understanding factors influencing the fit of these restorations is essential for clinical application.

Purpose of the Study:

• To investigate the impact of cusp inclination and cavity wall convergence/divergence on the marginal adaptation of machine-milled ceramic restorations.
• To compare the adaptation of feldspathic porcelain inlays fabricated using the Cerec 2 system under varying cavity preparation designs.

Main Methods:

• Sixty feldspathic porcelain inlay specimens (Vitablocs Mark 2) were fabricated using the Cerec 2 CAD/CAM system.
• Specimens were prepared with four cusp inclinations (0°, 15°, 30°, 45°) and three cavity forms (tapered box, regular box, undercut box).
• Restorations were cemented with a dual-activated luting agent, sectioned, and marginal adaptation was measured microscopically.

Main Results:

• Cusp inclination did not significantly affect the marginal adaptation of the ceramic restorations (P > 0.05).
• Inlays placed in undercut cavity preparations showed significantly poorer marginal adaptation compared to regular and tapered preparations at 0° and 15° cusp inclinations (P < 0.05).

Conclusions:

• Undercut box cavity preparations should be avoided when using the Cerec 2 ceramic restorative system to ensure optimal occlusal marginal adaptation.
• Regular or tapered box form cavity preparations are recommended for improved marginal adaptation in machine-milled ceramic restorations.