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Table 2 Characteristics of the included trials

From: The effectiveness of the early orthodontic correction of functional unilateral posterior crossbite in the mixed dentition period: a systematic review and meta-analysis

References Participants Treatment/retention/observation time Expansion obtained on the maxillary arch Success rate and relapse Correction of midline /mandibular width/other outcomes
Boysen et al. [39]
CCT
34 children UFPXB:
G1 (8.3 Y): 17 QH
G2 (8.6 Y): 17 EP
G1 (QH): treatment duration 101.2 D
G2 (EP): treatment duration 115.4 D
Retention: 3 M
Observation: 2 Y
IC: QH 5.1 mm
EP 3.5 mm**
IM: QH 5.6 mm
EP 4.6 mm*
  Mandibular IM: decreased in QH (− 0.02 mm)
Increased in EP (0.02 mm)*
Mandibular IC: increased in QH (0.01 mm)
Decreased in EP (− 0.16 mm)*
Brin et al. [40]
CCT
34 children:
TG (9.5 Y): 24 (UFPXB) EP
CG (9.8 Y): 10 normal
TG (EP): duration 10 M
Retention 6 M
IM increased in
EP (3 mm) and became similar to the CG
Success rate:
EP 50%
No relapse after 6 M
Midline deviation correction:95%
The mandibular arch width in TG: decreased (25% of the cases); increased (50%); remained the same (25%)
Bjerklin et al. [41]
CCT
38( FPXB):
G1 (9.3 Y): 19 QH
G2 (9.2 Y):19 EP
CG (8.8 Y): 19 normal
G1 (QH): 7.7 M
G2 (EP): 12.5 M
Retention 3–5 M
Observation 5.5 Y
IC: (QH): 1.6 mm
(EP): 2.3 mm*
IM: (QH): 3.6 mm
(EP): 2.9 mm*
Success rate in both groups was 100%
Relapse (after 5.5 Y):
(QH) 3/19
(EP) 1/19
No differences in the mandibular arch
Petren et al. [42]
RCT
60( FPXB):
A (9.1 Y): 15 QH
B (8.7 Y): 15 EP
C (8.3 Y): 15 composite onlay
D (8.8 Y): 15 CG
Group A: 4.8 M
Group B: 9.6 M
Group C: 1 Y
Retention:
Groups A and B:6 M
Observation: 1 Y
IC: A: 1.4 mm
B: 2.4 mm**
C: 0.5 mm
D: 0.2 mm*
IM: A: 4.6 mm
B: 3.5 mm**
C: 0.5 mm
D: 0.4 mm*
Success rate
A: 15/15 (100%)
B: 10/15 (66.6%)**
C: 2/15 (13.3%)
D: 0/15 (0%)*
Midline deviation correction:
A:14/15
B:12/15
C:6/15
D:3/15
Mandibular arch changes:
IC (*)
IM ( increased in B & D groups)
Godoy et al. [6]
RCT
99 (FPXB):
G1 (8 Y): 33 QH
G2 (7.8 Y): 33 EP
G3 (8.09 Y): CG
QH: 4.24 M
EP: 6.12 M
Retention: 6 M
Observation: 12 M (after cross bite correction)
IC: (QH): 4.5 mm
(EP): 1.8 mm*
IM: (QH): 5.7 mm
(EP): 4.46 mm*
Success rate (QH):100%
(EP):90.9%
(CG): 0%
Relapse: (QH): 9.1%
(EP): 9.1%
Mandibular arch changes:
IM: QH > EP & CG
Side effects occurred in:
(QH):39.4%
(EP): 27.3%
Petren et al. [43]
RCT
40 (PXB) with midline deviation:
A(9 Y): 20 QH
B (8.5 Y): 20 EP (withdrawal of 5 patients later)
CG (8.8 Y): 20 normal
Treatment duration: 1Y
Retention: 6 M
Observation: 3 Y
IC: A: 2.7 mm
B: 2.6 mm*IM: A: 4.1 mm
B: 3.8 mm*
Relapse after 3 Y: (QH): ½0
(EP): 0/15*
Midline deviation:
correction occurred in > 50% in both groups with no significant differences
Mandibular arch changes: IC:*
IM: B > A
Lippold et al. [44]
RCT
77 (FPXB):
A (8.3 Y): 37 bonded Hyrax followed by a U-bow activator ( withdrawal of 6 patients later)
B (8.2 Y): 40 CG ( withdrawal of 5 patients later)
Bonded Hyrax: 3.2 W
Retention: 12.6 W
U-bow activator: 36.8 W
IC: A: 2.6 mm
B: 1 mm**
IM:A: 5.1 mm
B: 0.8 mm**
  midline correction:
A > B
Mandibular arch changes:*
Sollenius et al. [45]
RCT
135 UFPXB:
1.QHS (9.3Y): 28 QH in SOC
2. QHG (9.5Y): 27 QH in GDC
3.EPS(8.7Y): 27 EP in SOC
4. EPG (9.2Y): 28 EP in GDC
5.Untreated group (8.5Y): 25
CG (9.3Y): 25 normal
Treatment duration:
QHS: 7.5 M
QHG: 8.2 M
EPS: 11.4 M
EPG: 12 M
Including 3 M for retention
IC: QHS > QHG & EPS & EPG**
IM: QHS > QHG & EPS & EPG**
Success rate:
QHS: 100%
QHG: 85.1%
EPS: 66.6%
EPG: 64.2%
Treatment by QHS was significantly more successful compared to other groups
 
Sollenius et al. [46]
RCT
110 (FPXB):
1. QHS (9.3Y): 28 QH in SOC
2. QHG (9.6Y): 27 QH in GDC
3. EPS (8.8Y): 27 EP in SOC
4. EPG (9.0Y): 28 EP in GDC
Number of appoint
QHS: 7.1
QHG: 8.4
EPS: 8.2
EPG: 9.2
Including 3 M of retention
  Success rate:
QHS: 100%
QHG: 85.18%
EPS: 66.6%
EPG: 64.28%
midline correction: QHS: 85.71%
QHG: 50%
EPS: 59.25%
EPG: 50%
  1. UFPXB: unilateral functional posterior cross bite, QH: quad helix, EP: expansion plate, CG: control group, TG: treatment group, RME: rapid maxillary expansion, IC: intercanine width, IM: intermolar width, SOC: specialist orthodontic clinics, GDC: general dentistry clinics, CO: centric occlusion, MO: maximum occlusion, XB: crossbite, N-XB: non-crossbite
  2. **Statistically significant difference, *Non-statistically significant difference