Since 2003 we have been using a system based on the Oxford Centre for Evidence-based Medicine (OCEBM) levels of evidence to indicate the quality of the summary articles we publish in the journal. Although OCEBM introduced an updated version of their level of evidence in 2011 (https://www.cebm.net/category/ebm-resources/loe/) we have continued to use their original one.

In addition to the OCEBM system for grading levels of evidence a plethora of grading systems exist and in 2004 the GRADE (Grading of Recommendations Assessment, Development and Evaluation) working group published a critical appraisal of six of the most prominent systems,1 and as a result proposed a new system for both rating the quality of evidence and the strength of recommendation.2,3 Since that time the use of the GRADE approach has increased, and it is now routinely seen in new and updated reviews from the Cochrane Oral Health Group as well as a broad range of other dental systematic reviews. As a consequence, we have decided to move over to GRADE for rating the quality of original studies summarised in the Evidence-based Dentistry journal.

GRADE distinguishes between quality assessment as part of a systematic review compared with quality assessment undertaken during guideline development. GRADE recognises four categories of evidence; high, moderate, low and very low that are typically applied to a body of evidence and defined as shown in Table1.

Table 1 GRADE quality of evidence and definitions
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Under the GRADE system a randomised controlled trial is initially assigned to be high quality, this is lowered if there is a risk of bias, inconsistency of results, indirectness of evidence, imprecision or publication bias. If the risks are serious the quality level is lowered by one level or by two levels if the risk is very serious. On the contrary the quality level is raised if there is a large magnitude of effect or plausible confounding, which would reduce a demonstrated effect or evidence of a dose-response gradient (Table 2).

Table 2 A summary of the GRADE approach to rating quality of evidence
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A majority of the summaries in Evidence-based Dentistry are of systematic reviews and a GRADE rating would normally be applied for each important individual outcome. However, for the journal's purposes we will only display the highest GRADE rating for any particular summary article and readers should bear this in mind.

Our revised GRADE graphic will appear on the bottom left hand column of the summary pages of Evidence-based Dentistry (EBD) and will differ from the standard GRADE graphic shown in table two in that we will substitute the plus graphic for a coloured circle as shown in Table 3.

Table 3 Key to GRADE graphic used in the Evidence-based Dentistry journal
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This new approach to identifying the quality of evidence summaries in the journal does to an extent simplify the GRADE approach as for reviews we will only be focusing on one outcome. However, the main intention of the evidence-based journal is to highlight quality evidence to our readers to encourage them to engage with original studies that are summarised in the journal. For those wanting to understand and explore the full details of the GRADE approach a wide range of resources are available in the GRADE Working Group website http://www.gradeworkinggroup.org/.