Abstract: Twenty two incompletely fractured teeth from 21 patients were restored by chrome cobalt alloy onlays, all of patients attended the followup study within 5 years. 16 onlays in 15 cases had good performance. 5 onlays, those were refixed timely after they had lost, still worked well. One case was extracted for “apicitis”. The clinical results showed that onlay restoration was the effective way for protecting incompletely farctured tooth, meanwhile, it is very important to prevent tooth from secondary caries, and onlay from coming out by means of accomplished preparation, accurate adjustment and regular reexamine.

Key words: onlay, incompletely fractured tooth, restoration