1. Subgroup analyses.
| Subgroup factor | Mean difference (95% confidence interval) | Test for subgroup differences | |
| Baseline prophylaxis | Yes | No | |
| QHPI | ‐0.44 (‐0.58 to ‐0.30) | ‐0.61 (‐0.82 to ‐0.41) | Chi2 = 1.92, df = 1, P value = 0.17, I2 = 47.8% |
| PSI | ‐0.13 (‐0.18 to ‐0.08) | ‐0.20 (‐0.26 to ‐0.14) | Chi2 = 3.01, df = 1, P value = 0.08, I2 = 66.7% |
| LSGI | ‐0.26 (‐0.34 to ‐0.18) | ‐0.30 (‐0.39 to ‐0.21) | Chi2 = 0.43, df = 1, P value = 0.51, I2 = 0% |
| GSI | ‐0.12 (‐0.18 to ‐0.07) | ‐0.16 (‐0.27 to ‐0.05) | Chi2 = 0.32, df = 1, P value = 0.57, I2 = 0% |
| Baseline plaque levels |
Low (0.50 to 2.36) |
High (2.45 to 4.40) |
|
| QHPI | ‐0.41 (‐0.57 to ‐0.25) | ‐0.54 (‐0.72 to ‐0.35) | Chi2 = 1.08, df = 1, P value = 0.30, I2 = 7% |
| PSI | ‐0.15 (‐0.18 to ‐0.13) | ‐0.14 (‐0.21 to ‐0.07) | Chi2 = 0.14, df = 1, P value = 0.71, I2 = 0% |
| Baseline gingivitis levels |
Low (0.71 to 1.42) |
High (1.49 to 2.11) |
|
| LSGI | ‐0.21 (‐0.30 to ‐0.13) | ‐0.33 (‐0.36 to ‐0.31) | Chi2 = 7.41, df = 1, P value = 0.006, I2 = 86.5% |
| GSI* | ‐0.13 (‐0.19 to ‐0.07) | ‐0.17 (‐0.22 to ‐0.12) | Chi2 = 0.92, df = 1, P value = 0.34, I2 = 0% |
df: degrees of freedom; GSI: Gingivitis Severity Index (proportion of sites bleeding, i.e. 2 or 3 on the Löe‐Silness Gingival Index); LSGI: Löe‐Silness Gingival Index (0 to 3 on an increasing scale); PSI: Plaque Severity Index (proportion of surfaces scoring > 3 on the Quigley‐Hein Plaque Index); QHPI: Quigley‐Hein Plaque Index (0 to 5 on an increasing scale).
*2 studies not included due to no reporting of baseline LSGI scores (Renvert 1995; Svatun 1993).