Garcia‐Godoy 2004.
| Methods | Title: placebo‐controlled, 6‐week clinical trial on the safety and efficacy of a low‐gel, 14% hydrogen‐peroxide whitening strip Trial design: parallel‐group, double‐blinded, randomised controlled trial Location: not reported Language: English Number of centres: 1 Recruitment period: not reported Funding source: Procter & Gamble |
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| Participants | Participants: consenting adults, mean age: 32.1 years Total number: 39 Inclusion criteria:
Exclusion criteria:
Number randomised: 39 Method of randomisation: not reported Method of allocation concealment: not reported Method of blinding: not reported Number evaluated: 35. 4 dropouts, 2 from each group |
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| Interventions | Total number of intervention groups: 2 Experiment: 14% hydrogen peroxide Control: placebo Duration of treatment: 3 weeks |
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| Outcomes | Improvement in tooth colour b*: decreased b* indicates reduced yellowness ΔL: increased ΔL is increased brightness ΔW: negative W indicates colour closer to white |
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| Notes | Sample size calculation: not reported Adverse effects: tooth sensitivity and oral irritation Health‐related quality of life: not reported Key conclusions of the study authors: "Twice‐daily use of Crest Whitestrips Supreme resulted in a highly significant improvement in tooth colour after 3 weeks, with colour improvement continuing over 6 weeks" |
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| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Quote: "randomised double‐blinded parallel‐group clinical trial. Eligible subjects were randomised to a low gel 14% ...or placebo group." However, method of randomisation is not mentioned |
| Allocation concealment (selection bias) | Unclear risk | Not mentioned |
| Blinding of participants and personnel (performance bias) All outcomes | Unclear risk | Quote: "randomised double‐blinded parallel‐group clinical trial." However, method of blinding is not mentioned |
| Blinding of outcome assessment (detection bias) All outcomes | Unclear risk | Quote: "randomised double‐blinded parallel‐group clinical trial." However, method of blinding is not mentioned |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Quote: "2 subjects 1 in each group discontinued treatment because of a treatment related adverse event" 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 |