Table 1 Glossary of terms

Systematic review

Cochrane [17] defines a systematic review as follows: “A systematic review attempts to identify, appraise and synthesize all the empirical evidence that meets pre-specified eligibility criteria to answer a specific research question. Researchers conducting systematic reviews use explicit, systematic methods that are selected with a view aimed at minimizing bias, to produce more reliable findings to inform decision making.”

Intervention review

Cochrane [17] defines an intervention review as follows: “Intervention reviews assess the effectiveness/safety of a treatment, vaccine, device, preventative measure, procedure or policy.”

Orthodontic interventions

Steegmans et al. [18] define orthodontic interventions as follows: “Orthodontic interventions refer to the use of any type of orthodontic appliance 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 [19, 20] 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 [21]

“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”

Spin [22]

“A specific reporting that fails to faithfully reflect the nature and range of findings and that could affect the impression that the results produce in readers, a way to distort science reporting without actually lying”

Misleading reporting related spin [23]

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

Misleading interpretation related spin [23]

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

Misleading (inappropriate) extrapolation related spin [23]

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 [24]

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.