Table 5.

Results of meta-analyses and single study estimates, related to microbiologic parameters (aligners vs fixed appliances)

Synthesis	No. of studies	Effect measure	95% CI	p-value	I2 (%)	Tau-squared (T2)
Adults
S. mutans (CFU > 105, 3 months)1	2	RR: 0.07	0.01, 0.49	0.008	0.0	–
S. mutans (CFU > 105, 6 months)1	2	RR: 0.22	0.10, 0.51	0.001	0.0	–
Lactobacilli (CFU > 105, 3 months)1	2	RR: 0.09	0.02, 0.47	0.004	0.0	–
Lactobacilli (CFU > 105, 6 months)1	2	RR: 0.19	0.08, 0.45	<0.001	56.9	–
Adolescents
S. mutans (presence, 1 month)2	1	RR: 0.86	0.64, 1.14	0.29	–	–
S. mutans (counts: 5th root, 1 month)2	1	MD: -2.22	-6.82, 2.38	0.34	–	–

CFU: colony forming units; CI: confidence intervals; MD: mean difference; RR: risk ratio. ¹Mummolo et al 2020a, Mummolo et al 2020b; 2 Sifakakis et al 2018.