| Characteristic |
Number of studies |
Slope estimate |
95% CI |
Slope interpretation |
P‐value |
| Mean baseline caries |
67 |
0.7% |
(0.07% to 1.3%) |
Increase in PF per unit increase in mean baseline caries |
0.03 |
| Fluoridated water |
56 |
3.2% |
(‐4% to 11%) |
Higher PF in presence of water fluoridation |
0.4 |
| Background fluorides |
56 |
0.6% |
(‐6% to 8%) |
Higher PF in presence of any background fluoride |
0.9 |
| Concentration of fluoride |
69 |
8.3% |
(1% to 16%) |
Increase in PF per 1000 ppm F |
0.03 |
| Frequency of toothbrushing |
70 |
14% |
(6% to 22%) |
Increase in PF moving from once to twice a day |
< 0.0001 |
| Intensity (freq times conc) |
69 |
5.9% |
(3.0% to 8.9%) |
Increase in PF equivalent to doubling from once to twice a day and increasing by 1000 ppmF |
< 0.0001 |
| Mode of use |
70 |
‐11% |
(‐18% to ‐4%) |
Lower PF with unsupervised toothbrushing |
0.03 |
| Allocation concealment |
70 |
3.2% |
(‐7% to 13%) |
Higher PF with poorly concealed allocation |
0.5 |
| Drop out |
70 |
2.6% |
(0.2% to 5%) |
Increase in PF per 10 drop outs |
0.04 |
| Length of follow up |
70 |
0.8% |
(‐4.2% to 5.7%) |
Increase in PF per extra year of follow up |
0.8 |
| SMFP vs NaF (indirect comparison) |
32 |
‐ 2.6% |
(‐11.8% to 6.5%) |
PF lower among SMFP trials |
0.6 |
| AmF vs NaF (indirect comparison) |
15 |
3.2% |
(‐11.0% to 17.3%) |
PF higher among AmF trials |
0.7 |
| SnF2 vs NaF (indirect comparison) |
29 |
‐4.8% |
(14.1% to 4.5%) |
PF lower among SnF2 trials |
0.3 |
