Table 4.

Studies	Mean age of intervention group	Type of expander	Activation protocol	2nd CBCT acquisition
Pangrazio-Kulbersh et al.	First group, 12.6; second group, 13.5	13 banded versus 10 bonded	4/6 weeks	After 6 months of retention
Riberio et al.	7.5 years	McNamara	NS	4 months after maxillary expansion
Chang et al.	12.9 years	Hyrax expander	1 activation for 28 days	3-4 months after maxillary expansion
Iwasaki et al.	9,96 years	NS	NS	1,27 years after first acquisition
Zhao et al.	12,8 years	Hyrax	1 or 2 times per day for 4/6 weeks	From 8 months to 2 years after first acquisition
El and Palomo	14 years	Hyrax	2-time activation per day	NS
Zeng and Gao	12,73 years	Hyrax	2/3 weeks	3 months after expansion
Christie et al.	9.9 years skeletal 10	Haas	30 days	Immediately after expansion
da Baratieri et al.	9.6 years	Haas	2-time activation per day	1 year after RME

NS, not specified.