Comparison 13. Vibrational appliances with fixed appliances versus fixed appliances only (control).

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
13.1 Mandibular incisor crowding (pre‐treatment and after initial alignment)	2		Mean Difference (IV, Fixed, 95% CI)	Subtotals only
13.1.1 Irregularity at baseline	2	122	Mean Difference (IV, Fixed, 95% CI)	‐0.42 [‐2.54, 1.70]
13.1.2 Irregularity at initial alignment	2	119	Mean Difference (IV, Fixed, 95% CI)	0.42 [‐0.05, 0.90]
13.2 Change in mandibular incisor crowding	2	119	Mean Difference (IV, Fixed, 95% CI)	0.24 [‐0.81, 1.30]
13.3 Time to alignment	2	94	Mean Difference (IV, Fixed, 95% CI)	‐3.70 [‐26.29, 18.89]