Hyland 2015.

Methods	Title: a new 3‐component formulation for the efficient whitening of teeth (Carbamide Plus) Trial design: randomised, double‐blinded, placebo‐controlled, clinical trial Location: Eastman Dental Hospital, UK Language: English Number of centres: 1 Recruitment period: not reported Funding source: SMT Ltd and DEL CAST studentship
Participants	Participants: adults Total number: 33 Inclusion criteria: not reported Exclusion criteria: heavily restored upper left central incisor or upper right canine pregnancy or breastfeeding previously undergone a course of vital tooth whitening smokers active dental disease severe dentine hypersensitivity uncontrolled dental disease unable to attend on data collection Number randomised: 32 Method of randomisation: not reported Method of allocation concealment: not reported Method of blinding: not reported Number evaluated: 32
Interventions	Total number of intervention groups: 3 5% carbamide peroxide gel 10% carbamide peroxide gel Placebo Duration of treatment: 2 hours per day for 2 weeks
Outcomes	Improvement in tooth colour ΔL, a*, b*: increase in ΔL and reduction in b* indicates whitening
Notes	Sample size calculation: not reported Adverse effects: not reported Health‐related quality of life: not reported Key conclusions of the study authors: "A new tooth‐whitening product Carbamide Plus containing urea, hydrogen peroxide, and STPP as active components containing 5% hydrogen peroxide has been shown to be as effective as the commercially available carbamide peroxide containing 10% hydrogen peroxide. There were no statistically significant differences between Carbamide Plus and 10% carbamide peroxide in tooth whitening at 2 weeks following daily wear of tooth whitening trays for 2 hours per day" Correspondence required: no Contact: BW Hyland; j.callan@ulster.ac.uk
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "The recruited subjects were randomly allocated to 1 of 3 study groupings: non‐active placebo gel..." However, method is not reported
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quote: "randomised, double‐blinded, placebo‐controlled clinical trial." However, method is not reported
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote: "randomised, double‐blinded, placebo‐controlled clinical trial." However, method is not reported
Incomplete outcome data (attrition bias) All outcomes	Low risk	No dropouts
Selective reporting (reporting bias)	Low risk	All outcomes described were reported. Conclusions are in accordance with the results
Other bias	Low risk	None