RESUMEN
PURPOSE: The purpose of this prospective, randomized, parallel-group clinical study was to evaluate and compare the clinical outcome of preformed zirconia crowns and preformed stainless steel crowns when used to restore permanent first molars. METHODS: Patients with severely decayed, badly broken down hypomineralized or hypoplastic permanent first molars that required a full-coverage restoration were invited to parti- cipate in the study. Sixty-nine healthy, cooperative children, ages six to 12 years, were recruited for the study. Following informed consent, 36 preformed zirconia crowns and 36 stainless steel crowns were placed and assessed at one week, three months, nine months, and 12 months accord- ing to the modified United States Public Health Service Ryge criteria. The parameters evaluated were: the time required for preparation and ce- mentation; plaque accumulation; marginal integrity; fracture of the crown; retention of cement; interference with the eruption of the permanent second molar; and parental acceptance. RESULTS: The clinical evaluation revealed statistically comparable performance in crown retention, fracture, marginal integrity, and plaque retention at 12 months between crown types. Preformed zirconia crowns were preferred by the parents primarily because of esthetics. However, a significant difference was seen in the clinical time required for the preparation and placement of preformed zirconia crowns, which was nearly twice that for stainless steel crowns. CONCLUSIONS: After 12 months of clinical evaluation, preformed zirconia crowns performed comparably to stainless steel crowns in their ability to restore decayed or hypomineralized permanent first molars. However, zirconia crowns took nearly twice as long to prepare, fit, and cement.
