Nearly half of dental randomized controlled trials published in German are not included in Medline

Randomized controlled trials (RCTs) are considered the most reliable type of clinical intervention studies. However, not all reports of RCTs are accessible in Medline. This can impede the validity of the results of systematic reviews. Ten German-language dental journals were manually searched to locate reports of controlled clinical trials published between 1970 and 2000. The publication type was determined and compared with Medline. Of the 15 777 articles, 210 reports of RCTs and 410 articles of non-randomized controlled clinical trials (CCTs) were identified. Only 56% of the RCTs and 75% of the CCTs are available in Medline. Of the 118 reports of RCTs registered in Medline. 15 are indexed with the correct Publication Type term. Our data suggest that (a) hand-searching plays a valuable role in identifying reports of clinical dental trials, and (b) a literature search in Medline is likely to yield incomplete results.