Preformed metal crowns may last longer than fillings

Data sources: Searches were made using the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase and the System for Information on Grey Literature in Europe (SIGLE).

Study selection: Randomised controlled trials (RCT) were chosen that assessed the effectiveness of PMC, compared with filling materials or in children where there had been no treatment of tooth decay in one or more primary molar teeth.

Data extraction and synthesis: Forty-seven records were retrieved by the search strategies, some of which proved to be duplicates. Ultimately, 14 studies were scrutinised. None met the inclusion criteria and six studies were excluded from the review because they were either retrospective in design or they reported prospective outcomes but were not randomised.

Conclusions: No RCT were available for appraisal. Although the use of PMC is recommended in clinical practice by the British Society of Paediatric Dentistry (BSPD), the evidence to support this is not strong, consisting mainly of case reports and uncontrolled studies. The lower quality levels of evidence that have been produced nevertheless have some strength, since clinical outcomes are consistently in favour of PMC even though many studies analyse casts placed on the most damaged of the pair of teeth. It is important that the absence of evidence for PMC is not misinterpreted as evidence for their lack of efficacy.