Summary of findings for the main comparison. CP gel in tray versus placebo for whitening teeth.
| Carbamide peroxide (CP) gel in tray compared to placebo for whitening teeth | ||||||
| Patient or population: adults undergoing bleaching Setting: home‐based Intervention: CP gel in tray Comparison: placebo | ||||||
| Tooth whitening ‐ assessed by the dentist | ||||||
| Comparison | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | Number of participants (studies) | Certainty of the evidence (GRADE) | Comments | |
| Risk with placebo | Risk with CP gel in tray | |||||
| 10% CP gel in tray versus placebo ‐ 6 months (higher RR indicates gel whiter) | Study population | RR 6.74 (3.15 to 14.40) | 109 (2 RCTs) | ⊕⊝⊝⊝ VERY LOW1, 2 | ‐ | |
| 107 per 1000 | 722 per 1000 (337 to 1000) |
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| 5% CP gel in tray versus placebo ‐ 2 weeks (higher shade indicates whiter) | The mean change in shade in the placebo group was 71.852 | Mean difference in shade change is 4.56 units higher in the CP gel group (1.52 higher to 7.59 higher) | ‐ | 21 (1 RCT) | ⊕⊝⊝⊝ VERY LOW1, 2 | ‐ |
| 10% CP gel with desensitiser versus placebo ‐ 2 weeks (higher shade indicates whiter) | The mean change in shade in the placebo group was 9.40 | Mean difference in shade change is 4.70 units higher in the CP gel group (3.28 higher to 6.12 higher) | ‐ | 37 (1 RCT) | ⊕⊝⊝⊝ VERY LOW1, 2 | ‐ |
| 10% CP gel (lighter shade) versus placebo ‐ 2 weeks (higher shade indicates whiter) | The mean change in shade in the placebo group was 1.40 | Mean difference in shade change is 4.50 units higher in the CP gel group (4.04 higher to 4.96 higher) | ‐ | 179 teeth (1 RCT) | ⊕⊝⊝⊝ VERY LOW1, 2 | Analysis done at tooth level |
| 10% CP gel (medium dark shade) versus placebo ‐ 2 weeks (higher shade indicates whiter) | The mean change in shade in the placebo group was was 1.20 | Mean difference in shade change is 9.30 units higher in the CP gel group (8.75 higher to 9.85 higher) | ‐ | 172 teeth (1 RCT) | ⊕⊝⊝⊝ VERY LOW1, 2 | Analysis done at tooth level |
| 10% CP gel (dark shade) versus placebo ‐ 2 weeks (higher shade indicates whiter) | The mean change in shade in the placebo group was 1.10 | Mean difference in shade change is 10 units higher in the CP gel group (9.44 higher to 10.56 higher) | ‐ | 176 teeth (1 RCT) | ⊕⊝⊝⊝ VERY LOW1, 2 | Analysis done at tooth level |
| Adverse effects | ||||||
| Main adverse events reported in majority of trials were mild and transient tooth sensitivity and oral irritation which occurred more in the intervention group compared to placebo | ||||||
| *The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI) CI: confidence interval; RCT: randomised controlled trial; RR: risk ratio | ||||||
| GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect Moderate certainty: we are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different Low certainty: our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect Very low certainty: we have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect | ||||||
1Downgraded for risk of bias ‐ unclear risk of bias due to lack of allocation concealment, performance and detection bias. 2Downgraded for imprecision ‐ low sample size and event rate.