Nathoo 1994.
| Methods | Title: clinical evaluation of Colgate Platinum professional tooth whitening system and Rembrandt lightening bleaching gel Trial design: single‐blinded, randomised, parallel‐group clinical trial Location: Colgate Palmolive Research Centre, USA Language: English Number of centres: 1 Recruitment period: not reported Funding source: Colgate Palmolive |
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| Participants | Participants: not reported Total number: 40 Inclusion criteria: not mentioned Exclusion criteria: not mentioned Number randomised: 40 (n = 20 per group) Method of randomisation: not reported Method of allocation concealment: reported Method of blinding: not reported Number evaluated: 38 (1 dropout from each group: n = 19 in each group) |
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| Interventions | Total number of intervention groups: 2 (tray versus tray) 10% urea peroxide, 30 minutes twice daily (Colgate Platinum) 10% urea peroxide, 30 minutes twice daily (Rembrandt lightening) Duration of treatment: 2 weeks |
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| Outcomes | Improvement in tooth shade (objective assessment): increase in L and reduction in b* indicates whitening Improvement in tooth shade (subjective assessment): Vita shade guide arrange in order of lightness: percentage increase |
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| Notes | Sample size calculation: not reported Adverse effects: not reported Health‐related quality of life: not reported Key conclusions of the study authors: "Colgate Platinum was 46% more effective at tooth whitening after 1 week, and 96% more effective after 2 weeks of treatment. The results demonstrated that the Colgate product was significantly superior versus Rembrandt at increasing tooth whiteness (increase in delta E), and tooth lightness (increase in delta L*). No adverse reactions were noted on clinical examination" Correspondence required: no Contact: Saleem A Nathoo, Colgate Palmolive Research Centre, Piscataway, New Jersey, USA |
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| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Quote: "Single‐blinded, randomised, parallel‐group clinical trial." However, method of randomisation not reported |
| Allocation concealment (selection bias) | Low risk | Quote: "The identity of the products was concealed neither the subjects nor investigator were informed about the identity of products or to which group the individual belonged" |
| Blinding of participants and personnel (performance bias) All outcomes | Unclear risk | Quote: "The identity of the products was concealed neither the subjects nor investigator were informed about the identity of products nor to which group the individual belonged" but details of the blinding method are not reported |
| Blinding of outcome assessment (detection bias) All outcomes | Unclear risk | Quote: "Single‐blinded, randomised, parallel‐group clinical trial." However, method is not reported |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Quote: "Of the 40 participants 38 participants completed the study (1 dropout from each group)" Comment: plausible effect size (difference in means) among missing outcomes not enough to 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 |