To study publication trends, as well as the number and proportion of randomised controlled trials covering different areas of periodontal research (RCT-Ps).
The study was based on Medline searches (MeSH terms) for the period 1980- 2000. The RCT-Ps (n = 675) were examined for relevance for different areas of periodontal research, journals of publication, and the countries of origin.
In periodontal research the annual number of publications had increased from 162 in 1980 to 440 in 2000. Moreover, clinical trials in periodontal research (CT-Ps) had increased more than 10-fold, and RCT-Ps more than 15-fold. More than 4 out of 10 RCT-Ps covered the areas 'periodontal surgery' and 'gingivitis and plaque treatment or prevention'. More than 6 out of 10 RCT-Ps in total and more than 8 out of 10 RCT-Ps about 'periodontal surgery', were published in two different journals. U.S.A was the most common country of origin of RCT-Ps, contributing to almost 4 out of 10 RCT-Ps during 1988-2000.
The annual number of RCT-Ps increased substantially during 1980-2000, and a few clinical research areas predominated. Future research should give priority to areas where clinical evidence is scarce and where high-quality RCT-Ps are most needed.