Probability of fracture of all-ceramic crowns

Purpose: The study compared the probablity of fracture of 4 systems of all- ceramic crowns fabricated on maxillary central incisors. Materials and Meth ods: The 4 all-ceramic crown systems were: (1) a glass-infiltrated, sintere d alumina system (In-Ceram) fabricated conventionally, (2) the same system with machine-milled alumina cores (CEREC 2), (3) a heat-press, leucite-rein forced glass-ceramic system (IPS Empress), and (4) a high-purity, high-dens ity alumina system (Procera). Ten crowns of each system were fabricated and compressed at 45 degrees at the palatal surface until failure. The data we re analyzed with the Weibull method. Results: There were no significant dif ferences in the probability of fracture among the 4 systems studied. Conclu sion: The likelihood of fracture of these crown systems on central incisors should be similar.