All-ceramic tooth-supported single crowns have acceptable 5-year survival rates

The databases Medline/PubMed, EMBASE, the Cochrane Library, Chinese Biomedical Literature Database and the China National Knowledge Infrastructure were searched. Additional hand searches were conducted in the journals.

Randomised controlled trials, prospective cohort studies and retrospective studies with follow-up of 36 months or longer were included.

Data were extracted independently in duplicate. The annual core and veneer fracture rates of various tooth types were estimated and compared using Poisson regression.

37 studies were included; two RCTs, 25 prospective cohorts and 10 retrospective studies. Based on the calculated results, all-ceramic crowns had an acceptable overall five-year fracture rate of 4.4% irrespective of the materials used. Five-year fracture rates were significantly higher for molar crowns (8.1%) compared to premolar crowns (3.0%), and the difference between anterior (3.0%) and posterior crowns (5.4%) also achieved significance. Core fracture rates had a five-year incidence of 2.5%, and a significantly higher core fracture rate was found in the posterior region (3.9%). The overall five-year incidence of veneer fracture was 3.0%, and no clear difference was found between restored tooth types, with incidences of 2.0%, 2.5%, 1.0%, and 3.0% for incisor, canine, premolar, and molar crowns, respectively.

Within the limitations of this study's protocol, the current evidence suggests that dental ceramic materials demonstrated acceptable five-year core and veneer fracture incidences when used for tooth-supported single crowns in both anterior and posterior segments. Higher fracture tendency for posterior crowns was the trend for all-ceramic crowns, while molar crowns showed a significantly higher fracture rate than premolar crowns. Randomised controlled trials with large sample sizes be undertaken to obtain more definitive results.