Evidence-Based Dentistry - an Ever-Evolving Field of Research and Information.

Abstract

The Cochrane Library, founded in 1993 and named after Archie Cochrane, is a collection of databases covering the health sciences. A central component of this library is the collection of Cochrane Reviews, which is a voluminous repository of systematic reviews and meta-analyses that review, analyse and interpret the results of previously published health science research. A principal aim of the Cochrane Library is to distill the results of well-conducted controlled trials into an easily accessible form and is today recognized as a very important resource for evidence-based medicine. It is considered the premier source of systematic reviews and meta-analyses. Nestled within this is the Cochrane Oral Health Group which identifies key clinical issues in dentistry and then undertakes systematic reviews in these areas to provide a stand-alone evidence-based resource for oral health. At present there are over 150 reviews on a very broad range of clinical topics within the Cochrane Oral Health Group's database.1 However, the Cochrane Library is not the only source of systematic reviews and meta-analyses because nearly all scientific journals publish such reviews. Indeed, a very simple search in ‘Web of Science’ using the search term ‘systematic review’ in the title of published papers results in 209 928 results. If the search is focused only on oral health as a keyword the number of results is 5189. Clearly this is becoming an unsustainable avenue of investigation and on a daily basis yet another systematic review is published in almost any area of oral health we are interested in. With the explosion in publication of systematic reviews a new field of endeavour has arisen known as ‘umbrella reviews’. Indeed this issue of the Australian Dental Journal contains the first umbrella review published in this journal.2 Simply defined, umbrella reviews are reviews of systematic reviews. The synthesis of data from existing systematic reviews into umbrella reviews allows the results of systematic reviews on specific topics or questions to be analysed, compared and contrasted. Since systematic reviews should only consider reviewing studies of the highest quality, the potential exists for umbrella reviews to consider and review only the highest level of current available evidence, namely systematic reviews and meta-analyses. In addition to the driving force for umbrella reviews to deal with the ever-expanding number of systematic reviews being published, they also improve ‘fast access’ to the latest available high quality data and improve the evidence base for clinical practice. While this may all seem remote from everyday practice, systematic reviews and umbrella reviews are important as they can guide us in decision-making processes when choosing clinical procedures, materials and products. While many a cynic would say nearly all reviews conclude with a statement along the lines that more studies are required before a clear decision can be made, careful assessment of the distilled information should guide us in making informed decisions based on the knowledge available to date. Happy reading!