Six-year survival of single crowns - A massive data analysis

Numerous clinical trials have proven the long-term stability of metal and metal-ceramic crowns. However, data on their performance under practice conditions are rare.

To evaluate the longevity of crowns by means of massive data analyses.

The data were extracted from the data warehouse of a major German national health insurance company (BARMER, Berlin, Germany). The analysis focused on crown types with the lowest deductibles. Metal crowns and metal-ceramic crowns with ceramic veneering on the vestibular aspects of teeth 15-25 and 34-44 placed from 2012 to 2017 were included. The placement of the crowns, crown removals and tooth extractions were identified using the corresponding fee codes. Kaplan-Meier survival analyses were conducted for the outcomes "crown removal or extraction" and for "extraction".

The cumulative six-year survival rates were 88.0 % for the outcome "crown removal or extraction" and 92.5 % for the outcome "extraction" (N = 192,868). The survival functions had slightly steepening but close to linear courses.

The outcome of the treatment with metal and metal-ceramic crowns was moderately inferior in comparison to clinical trials. However, treatment with metal and metal-crowns is judged to be a reliable and safe option under practice conditions.

Clinicians must inform patients about potential treatment outcomes. Therefore, additional knowledge about single crown outcomes under general practice settings based on large database analyses is important.