Table 1 Glossary of terms

Systematic review

The Cochrane glossary [12] defines a systematic review as “‘A review of a clearly formulated question that uses systematic and explicit methods to identify, select, and critically appraise relevant research, and to collect and analyse data from the studies that are included in the review. Statistical methods (meta-analysis) may or may not be used to analyse and summarise the results of the included studies.”

Intervention review

Cochrane [14] defines an intervention review as follows: “Intervention reviews assess the benefits and harms of interventions used in healthcare and health policy.”

Orthodontic interventions

Steegmans et al. [15] define orthodontic interventions as follows: “Orthodontic interventions refer to the use of any type of orthodontic appliance that are used to move teeth or change the jaw size or position for orthodontic purposes. These interventions also include appliances to maintain or stabilize the results of orthodontic treatment, for example retainers.”

Adverse effect

Cochrane [12, 13] defines an adverse effect as “an adverse event for which the causal relation between the intervention and the event is at least a reasonable possibility.”

Spin [3]

“Distorted presentation of study results.”

Spin [3]

“A misrepresentation of study results, regardless of motive (intentionally or unintentionally) that overemphasizes the beneficial effects of the intervention and overstates safety compared with that shown by the results.”

Spin [2]

“A specific intentional or unintentional reporting that fails to faithfully reflect the nature and range of findings and that could affect the impression the results produce in readers.”

Misleading reporting related-spin [4]

“Incomplete reporting of the study results that could be misleading for the reader.”

Misleading interpretation related-spin [4]

Inadequate interpretation of the study results overestimating the beneficial effect of the intervention.

Misleading extrapolation related-spin [4]

Inappropriate generalization of the study results by inadequate (1) extrapolation from the population, interventions, or outcome actually assessed in the study to a larger population, different interventions, or outcomes, or (2) inadequate implications for clinical practice.

Spin (in the abstract) on adverse effects of interventions

Incomplete or inadequate reporting, interpretation, or extrapolation (or a combination of these variables) of findings on adverse effects of interventions in the abstract that could be misleading for the reader.