Krause 2008.

Methods	Title: subjective intensities of pain and contentment with treatment outcomes during tray bleaching of vital teeth employing different carbamide peroxide concentrations Trial design: double‐blinded, randomised controlled trial Location: university Language: English Number of centres: 1 Recruitment period: not reported Funding source: not reported
Participants	Participants: mean age 31 years Total number: 30 Inclusion criteria: patients with teeth not discoloured for extrinsic or intrinsic reasons non‐smokers Exclusion criteria: not reported Number randomised: 30 Method of randomisation: computer generated numbers Method of allocation concealment: not reported Method of blinding: unlabelled similar packs Number evaluated: 30
Interventions	Total number of intervention groups: 3 10% carbamide peroxide tray 17% carbamide peroxide tray 0% carbamide peroxide tray Duration of treatment: 7 days
Outcomes	Pain sensation Patient contentment with bleaching: 0 no contentment, 100 maximum contentment
Notes	Sample size calculation: not reported Adverse effects: not reported Health‐related quality of life: yes, patient satisfaction Key conclusions of the study authors: "Application of carbamide peroxide–containing bleaching agents to vital teeth causes pain correlated with the agent's concentration. Since both highly and less concentrated gels might result in a similar contentment with the treatment outcome, the use of highly concentrated agents appears not to be justified to improve vital tooth colour" Contact: Felix Krause, fkrause@uni‐bonn.de
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "kits were assigned to the patients employing computer‐generated random numbers by a different operator"
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "Unlabelled treatment kits numbered consecutively. Thus, both the operator and the patient were unaware of the..."
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "Unlabelled treatment kits numbered consecutively. Thus, both the operator and the patient were unaware of the..."
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants completed the study
Selective reporting (reporting bias)	Low risk	All outcomes described were reported. Conclusions are in accordance with the results
Other bias	Low risk	None