The aim of the present review was to evaluate by means of a systematic review and meta-analysis the hypothesis of no difference in failure rates between amalgam and composite resin posterior restorations.
Randomized controlled trials, controlled clinical trials and prospective and retrospective cohort studies were included in this review. The eligibility criteria included clinical trials in humans with at least 12 months of follow-up comparing the failures rates between occlusal and occlusoproximal amalgam and composite resin restorations. Clinical questions were formulated and organized according to the PICOS strategy.
An electronic search without restriction on the dates or languages was performed in PubMed/MEDLINE, Cochrane Central Register of Controlled Trials, and Web of Science up until March 2015.
The initial search resulted in 938 articles from PubMed/MEDLINE, 89 titles from the Cochrane Central Register of Controlled Trials, and 172 from the Web of Science. After an initial assessment and careful reading, 8 studies published between 1992 and 2013 were included in this review. According to the risk of bias evaluation, all studies were classified as high quality.
The results of this review suggest that composite resin restorations in posterior teeth still have less longevity and a higher number of secondary caries when compared to amalgam restorations. In relation to fractures, there was no statistically significant difference between the two restorative materials regarding the time of follow-up.
There is currently a worldwide trend towards replacing amalgam restorations with mercury-free materials, which are adhesive and promote aesthetics. It is important to perform an updated periodic review to synthesize the clinical performance of restorations in the long-term.