Survival of In-Ceram crowns in a private practice: A prospective clinical trial

Statement of problem. Prior reports on some all-ceramic crown systems have indicated high failure rates through fracture. Purpose. This study prospectively evaluated the survival of infiltrated alumina crowns (In-Ceram) in a private practice. Material and methods. All the In-Ceram crowns placed in a prosthodontic practice since its introduction in 1990 were serially included. Patients were recalled at 6 monthly intervals. Those who did not attend in the previous 6 months were contacted by telephone and a series of answers to standardized questions recorded. The few patients who were lost to follow-up or who died were removed from the study from the time of last contact. Results. A total of 408 crowns in 107 patients were followed for periods from 1 to 86 months. As the 3-year data combined a meaningful period of service with a large sample size, these data were focused on. The 3-year survival rate was 96% for a sample size of 223. Three-year data indicated that core fracture and porcelain fracture occurred at rates of approximately 0.6% and 0.3% per year, respectively. Otherwise sound restorations were removed at a rate of approximately 0.3% per year for esthetic, endodontic, or prosthetic reasons. Anterior crowns tended to have a slightly higher 3-year survival rate (98%) than premolars or molars (94%). Conclusion. Clinical failure rate of In-Ceram crowns was low. Crowns were lost because of core fracture, porcelain fracture, and removal without failure. Failure tended to be more common for molar and premolar crowns than for anterior crowns.