Delgado 2007.

Methods	Title: tooth‐whitening efficacy of custom tray‐delivered 9% hydrogen peroxide and 20% carbamide peroxide during daytime use: a 14‐day clinical trial Trial design: double‐blinded, randomised controlled clinical trial Location: University of Puerto Rico Language: English Number of centres: 1 Recruitment period: not reported Funding source: Colgate
Participants	Participants: 25 to 64 years of age Total number: 46 Inclusion criteria: healthy male and female subjects aged 21 to 68 years availability for the 2 weeks duration of the study minimum average Vita shade of A3 for all 6 maxillary anterior teeth 6 natural maxillary anterior teeth must be present and free of large restorations or extrinsic stains covering more than 1/3 of the facial tooth surface or a maximum of 1 dental prosthetic crown/facial veneer Exclusion criteria: presence of orthodontic appliances presence of tumours or significant pathology of the soft or hard tissues of the oral cavity presence of moderate or advanced periodontal disease (ADA III or IV) presence of 5 or more carious lesions requiring immediate care use of stain‐inducing medications or oral use products 1 month prior to, or anytime during, the 2 weeks of the study participation in any other clinical study or test panel in the last month pregnant or lactating women allergies to tooth whitening products, personal care consumer products, or their ingredients Number randomised: 46 Method of randomisation: random list Method of allocation concealment: not reported Method of blinding: not reported Number evaluated: 37
Interventions	Total number of intervention groups: 2 Group I: Colgate Visible White containing 9% hydrogen peroxide (9% HP) Group II: Opalescence containing 20% carbamide peroxide (20% CP) Duration of treatment: 30 minutes for 2 weeks
Outcomes	Improvement in tooth shade The shade guide tabs were arranged B1 to C4 representing the 1 to 16 scale
Notes	Sample size calculation: not reported Adverse effects: gingival irritation Health‐related quality of life: not reported Key conclusions of the study authors: "Both 9% hydrogen peroxide and 20% carbamide peroxide products effectively whitened teeth after 5, 7 and 14 days of once‐a day 30‐minute applications. 9% hydrogen peroxide produced a statistically significant tooth shade improvement compared to the tooth whitening effect of 20% carbamide peroxide after 5 days of product use. Colgate Visible White 9% hydrogen peroxide and Opalescence (20% carbamide peroxide) had a similar whitening effect after 7 and 14 days of use. Both tooth whitening products tested produced little tooth sensitivity or gingival irritation" Contact: Evaristo Delgado; edelgadoc@yahoo.com
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Participants were assigned following a random list to 1 of the 2 treatment groups"
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quote: "randomised, single‐centre, parallel‐group, double‐blinded clinical trial." However, method is not reported
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote: "randomised, single‐centre, parallel‐group, double‐blinded clinical trial." However, method is not reported
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Quote: "9 dropouts noted" Comment: 7 failed to keep up with study visits. Unbalanced number in both groups (20% CP: n=16 and 9% HP: n = 21). We are not sure if plausible effect size (difference in means ) among missing outcomes may have a clinically relevant impact on observed effect size
Selective reporting (reporting bias)	Low risk	All outcomes described were reported. Conclusions are in accordance with the results
Other bias	Low risk	None