Recent advances in composite CAD/CAM blocks.

THE INTERNATIONAL JOURNAL OF ESTHETIC DENTISTRY The introduction of composite CAD/ CAM blocks has generated new indirect restorative materials with improved properties when compared to artisanal, light-cured composites. There is, however, some confusion about the different available products, which is exacerbated by incomplete information provided by manufacturers, who sometimes refer to them as “hybrid ceramics,” while a recent classification has termed them “resin-matrix ceramics.”1 Advances made in current composite CAD/CAM blocks are associated with: 1) new microstructures: classic dispersed filler microstructure on one side and resin infiltration of a ceramic network (polymer-infiltratedceramic-network or PICN) on the other; 2) new polymerization modes: with high temperature (HT), or with high temperature/high pressure (HT/HP); 3) new matrix composition: UDMA as the main component instead of Bis-GMA; 4) augmented filler content; and 5) more homogeneous structures with fewer flaws. Consequently, two classes of CAD/CAM blocks must be distinguished: those with dispersed fillers, which are HT polymerized and constitute most of the marketed products (eg, Lava Ultimate, 3M; Cerasmart, GC; Shofu Block HC, Shofu), and PICN materials, which are HT/HP polymerized (Enamic, Vita).2 PICN maRecent advances in composite CAD/CAM blocks