Table 4

Study	Year of publication	Number of patients	Materials and methods			Outcome measures
			TMD (mm)	Evaluation methods	Follow-up	Transverse skeletal expansion		Transverse skeletal relapse		Dental arch expansion				Dental arch relapse
			TMD (mm)	Evaluation methods	Follow-up	Mean (SD), mm		Mean (SD), mm		Mean (SD), mm				Mean (SD), mm
Del Santo et al. [25]	2000	20	NR	Dental cast X-ray	15 months (6 - 31)	Region	PO - PD	Region	PD - FFU	Region	PO - PD	Region	PO - FFU	NR
						BG	0.7 (4.4)	BG	0.7 (4.7)	ICD	3.2 (3.3)^a	ICD	2.4 (1.9)^b
						BAG	1.2 (4.4)	BAG	1.2 (4.1)			IPMD1	3.5 (2.4)^b
						ICD	3.2 (3.3)^a	ICD	0.5 (3.3)			IPMD2	4.9 (3.9)^b
						IMD	2.2 (4.2)^a	IMD	-0.4 (3)	IMD	2.2 (4.2)^a	IMD1	5 (3.2)^b
						IMD	2.2 (4.2)^a	BM	0.5 (1.4)	IMD	2.2 (4.2)^a	IMD2	4.1 (3.7)^a
Ploder et al. [26]	2009	20	NR	Dental cast X-ray	3 months	Region	PO - PD	NR		Region	PO - PD			NR
						ICD	3.4 (2)			ICD	4.2 (1.8)
						IPMD1	3.6 (1.8)			IPMD1	5 (2)^c
						IPMD2	3.3 (1.4)			IPMD2	4.7 (2)^c
						IMD1	3.2 (1.5)			IMD1	4.3 (1.7)^c
						IMD2	2.2 (1.8)			IMD2	3.6 (1.3)
Seeberger et al. [27]	2011	19	> 4	CT-scan	3 months	Region	PO - PD	NR		Region	PO - PD			NR
						IPRD	2.9 (1.8)^d			IPD	4.8 (1.6)^d
						IMRP	2.6 (2.1)^d			IMD	4.9 (1.3)^d
						IMFD	2.7 (1.2)^d			IMD	4.9 (1.3)^d

^aP-value < 0.05 (paired t-test), ^bP-value < 0.01 (paired t-test), ^cP-value < 0.05 (statistical test as not reported), ^dP-value < 0.05 (Wilcoxon signed rank test).
BAG = biantegonial; BG = bigonial; CT = computed tomography; FFU = final follow-up; ICD = inter-canine distance; IMD = inter-molar distance; IMD1 = first inter-molar distance; IMD2 = second inter-molar distance; IPD = inter-premolar distance; IPMD1 = first inter-premolar distance; IPMD2 = second inter-premolar distance; IMFD = inter-mandibular mental foramen distance; IMRP = inter-molar root distance; IPRD = inter-premolar root distance; PD = post-distraction; PO = preoperative; NR = not reported; SD = standard deviation; TMD = transverse mandibular deficiency.