Longevity of posterior composite restorations: a systematic review and meta-analysis

In the 12 studies ,a total, 2,816 restorations (2,585 Class II and 231 Class I restorations) were included in the analysis, of which 569 had failed at the end of the observation periods.
In the first year after restoration placement, the reason for failure is almost exclusively endodontic complications, while in later years few endodontic failures are seen and caries and fractures are the main failure reasons.
Study confirms that larger restorations have a higher risk for failure, since every extra surface included in a restoration increases this risk by 30%- 40%
When the Annual failure rate for all composites was considered results showed a mean annual failure rate of 1.8 % at 5 and 2.4 % at 10 years for posterior composite restorations (mainly class II in contrast to the earlier reported studies)