Mokhlis 2000.

Methods	Title: clinical evaluation of carbamide peroxide and hydrogen peroxide whitening agents during daytime Trial design: split‐mouth, double‐blinded, randomised controlled trial Location: University Purdue, Indianapolis, USA Language: English Number of centres: 1 Recruitment period: not reported Funding source: funded by Ultradent products Inc.
Participants	Participants: not reported Total number: 24 Inclusion criteria: 6 maxillary anterior teeth present and free of any restorative material covering more than 1/6 of their labial surfaces 6 anterior teeth darker than B54 and lighter than B85 on the Trubyte Bioform Colour Ordered Shade Guide (Dentsply Trubyte) at least 18 years of age willing to sign a consent form and able to return for periodic examinations willing to refrain from use of tobacco products during the study period Exclusion criteria: medical condition that might interfere with the study results or require special attention Gingival Index score > 1 or gross pathology in the mouth tetracycline‐stained teeth or having undergone endodontic therapy in any of the maxillary anterior teeth use of professionally‐applied tooth whiteners within the past 5 years use of any kind of tobacco products during the past 30 days pregnant or lactating women Number randomised: 24 Method of randomisation: reported Method of allocation concealment: reported Method of blinding: not reported Number evaluated: 24
Interventions	Total number of intervention groups: 2 20% carbamide peroxide gel 7.5% hydrogen peroxide gel Duration of treatment: 2 weeks
Outcomes	Change in colour: ΔL, a*, b* values were recorded. Increase in L and reduction in b* indicated whitening Tooth and soft tissue sensitivity: 5‐point scale: 1 none; 2 mild; 3 moderate; 4 considerable; and 5 severe
Notes	Sample size calculation: no Adverse effects: tooth and soft tissue sensitivity Health‐related quality of life: not reported Key conclusions of the study authors: "Use of the 20% CP resulted in significantly more lightness than the 7.5% HP during the first 14 days of the study, but at the end of the study, there was no significant difference between products with regard to tooth lightness. In addition, the authors found no statistically significant difference between products with regard to gingival or tooth sensitivity" Contact: GR Mokhlis, Indiana University School of Dentistry, Indianapolis, USA
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "The subjects were randomised according to the baseline shade guide into 2 groups by a study monitor not directly involved in the study"
Allocation concealment (selection bias)	Low risk	Quote: "A study monitor assigned side of the mouth and the other gel to the opposite side. The monitor then labelled each box of bleaching gel accordingly"
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Double‐blinded study but method of blinding not reported
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Double‐blinded study but method of blinding not reported
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "All 24 patients 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