Botelho 2017.

Methods	Title: a randomised controlled trial of home bleaching of tetracycline‐stained teeth Trial design: randomised, examiner‐blinded controlled trial Location: University of Hong Kong Language: English Number of centres: 1 Recruitment period: not reported Funding source: not reported
Participants	Participants: tray group: mean age 28.7 years; strip group: mean age 30.4 years Total number: 36 Inclusion criteria: tetracycline stained teeth maxillary anterior teeth sound or minimally restored able to attend 4‐month review Exclusion criteria: subjects under 18 medically unfit pregnant or lactating uncontrolled oral disease or infection history of tooth whitening treatment smoker allergy to hydrogen peroxide or carbamide peroxide Number randomised: 26 Method of randomisation: coin toss Method of allocation concealment: not reported Method of blinding: not reported Number evaluated: 24 (2 dropouts (1 for each group) at follow‐up)
Interventions	Total number of intervention groups: 2 Tray: 15% carbamide peroxide Strip: 6.5% hydrogen peroxide Duration of treatment: 3 months
Outcomes	Improvement in tooth colour a*, b* and ΔL were recorded Whitening benefit was represented by negative b* (yellowness reduction), and positive ΔL (increasing lightness)
Notes	Sample size calculation: done Adverse effects: sensitivity Health‐related quality of life: not reported Key conclusions of the study authors: "Both groups experienced noticeable and significant ΔL*a*b* improvement at the end of the trial in comparison to the baseline. Significant improvement was observed in the first month for the tray group and in the first 2 months for the strip group (P < 0.05). While greater lightness improvement was observed in the tray group over the strip group in the first month, the opposite was noticed in the second month. There was no difference between 2 groups at the end of this trial and no adverse reactions were observed" Correspondence required: no Contact: Dr Botelho MG; botelho@hku.hk
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Participants were randomly assigned to either group….. tossing coin"
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quote: "Participants were clinically review by one reviewer who was blinded to their treatment." However, method of blinding is not reported
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote: "Participants were clinically review by one reviewer who was blinded to their treatment." However, method of blinding is not reported
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "..each group had 1 participant that did not attend 2 months review" Comment: missing outcome data balanced in numbers across intervention groups
Selective reporting (reporting bias)	Low risk	All outcomes described were reported. Conclusions are in accordance with the results
Other bias	Low risk	None