Nathoo 2001.
| Methods | Title: comparative 7‐day clinical evaluation of 2 tooth whitening products Trial design: double‐blinded, parallel‐group, randomised controlled clinical trial Location: not reported Language: English Number of centres: 1 Recruitment period: not reported Funding source: Colgate Palmolive |
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| Participants | Participants: 18 to 65 years old Total number: 60 Inclusion criteria: adults with shade darker than A3 Exclusion criteria: not reported Number randomised: 60 Method of randomisation: not reported Method of allocation concealment: not reported Method of blinding: syringes were coded and wrapped Number evaluated: 58 |
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| Interventions | Total number of intervention groups: 2 5% carbamide peroxide in tray 10% carbamide peroxide in tray Duration of treatment: 1 week, 6 to 8 hours per day |
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| Outcomes | Improvement in tooth shade: Vita shade guide: tabs arranged from dark to light ΔL, a*, b* values: increase in ΔL and decrease in b* indicates lightening of teeth |
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| Notes | Sample size calculation: not reported Adverse effects: hypersensitivity: sensitivity as reported ‐ as yes or no questions Health‐related quality of life: not reported Key conclusions of the study authors: "...whitening data showed that there was no significant difference between the 2 products after 1 week. The data suggest that these products are clinically equivalent for tooth whitening. However, the subjective data collected on tooth hypersensitivity showed that the product containing 5% carbamide peroxide was associated with less discomfort. Of the group using the 5% carbamide peroxide product, 20% reported transient sensitivity of their teeth after product use for 1 week compared with 53% of the group using the product with 10% carbamide peroxide. The product containing 5% carbamide peroxide was associated with less tooth hypersensitivity after 1 week of application" 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: "Double‐blinded, randomised, controlled, parallel‐group clinica trial." However, method of randomisation is not mentioned |
| Allocation concealment (selection bias) | Unclear risk | Not mentioned |
| Blinding of participants and personnel (performance bias) All outcomes | Low risk | Quote: "The identity of the products were wrapped, neither the investigator no subjects were informed about.." |
| Blinding of outcome assessment (detection bias) All outcomes | Low risk | Quote: "The identity of the products were wrapped, neither the investigator no subjects were informed about.." |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Quote: "of the 60 participants who began the study 29 matched pairs (n = 58) remained throughout the study" 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 |