Survey of systematic reviews in dentistry

Although systematic reviews are the backbone of evidence-based dentistry, they have appeared infrequently in the clinical dental literature and their importance may not be recognized by dentists. The authors describe the steps taken in systematic reviews and perform a literature survey to identify published systematic reviews of topics relevant to clinical dentistry.

The authors searched MEDLINE and the Cochrane databases of systematic reviews and abstracts of reviews of effectiveness, as well as identified reviews that were known to the authors but not found in the searches. Systematic reviews included in this survey stated the intention to identify all relevant articles within predefined limitations, applied defined exclusion and inclusion criteria, and presented complete raw or synthesized data from included studies.

This literature survey identified 131 systematic reviews, 96 of which had direct clinical relevance. During the past 14 years, clinically relevant systematic reviews have been published with increasing frequency. These reviews vary in the types of studies included and the assessment of those studies. The results of the reviews also varied in their definitiveness, with 17 percent finding the evidence to be insufficient to answer the key question. An additional 50 percent of the 96 reviews hedged in answering the key question, by noting that the supporting evidence was weak in quality or limited in quantity.

The number of systematic reviews that address clinical topics in dentistry is small but growing. However, the authors of more than one-half of these reviews believed that the evidence available to answer the key question was not strong.

As systematic reviews continue to grow, dentistry will become better informed about the adequacy and congruence of the scientific evidence underpinning clinical practice.