A 3-year study of inlays milled from machinable ceramic blocks representing 2 different inlay systems

Objective: The aim of this study was to evaluate the clinical performance of ceramic inlays made from machinable ceramic blocks. Method and materials: The 2 inlay systems involved computer-aided design and computer-aided machining (Cerec Cos 2.1) or copy-milling technique (Celay). The study comprised 15 Celay inlays and 15 Cerec inlays placed in 17 patients. The inlays were evaluated clinically at baseline (1 week) as well as 1 and 3 years later (modified California Dental Association quality evaluation system). Results: One Celay inlay fractured after 1 year of service, and 2 Cerec inlays were replaced, 1 after 6 months and 1 after 1 year, because of pulpal pain and persisting hypersensitivity. One Celay inlay lost retention after 2 years. At the 3-year evaluation, chipping and hairline cracks were seen in 2 Celay inlays. Progressive disintegration of the marginal luting cement was seen for both Celay and Cerec inlays. The remaining 25 inlays performed satisfactorily throughout the 3-year period. Conclusion: Because of their relatively high failure rate, these inlays should be reserved for esthetic indications.