Table 1 Study characteristics and results

Barker et al. 2023 [15]

NRCT

Full Class II, division 1 malocclusion; mandibular retrognathism; mild transverse maxillary deficiency.

Acrylic-splint Herbst appliance

The average expansion time was 15 days. The mean maxillary expansion achieved was 3.19 mm.

Mandible was advanced 6 mm.

and opened 4 mm vertically.

Stepwise activations were completed

/

16

12.6y ± 11.5 months

BMI: 18.3 ± 1.8

PSG

cephalogram

Magnetic Resonance Imaging

12-months

The number of respiratory effort–related arousals (RERAs) and the respiratory disturbance index (RDI)decreased after treatment.

There was a reduction in the number of respiratory effort–related arousals (7.06 ± 5.37 to 1.31 ± 1.45 per hour of sleep) due to an increase in airway volume.

Schütz et al. 2011 [16]

Case-

control

prospective

The treatment group demonstrated a skeletal Class II pattern, with a reduced mandibular length. The OSA patients had slightly narrower inter-tooth distances at all levels measured.

Modified monobloc

(full occlusal coverage with maxillary expansion screw and tongue retainer). A Tucat’s pearl on a sliding wire was used to determine the reference point for the

tip of the tongue.)

This custom-made appliance incorporated full occlusal

coverage and a central maxillary screw, to allow for

accompanying expansion as the mandible was advanced.

Group 1: Treated

Group 2: Untreated

-Group 1:

20

-Group 2:

20

-Group 1:

10 M/10F

5.91 ± 1.14y

10M/10F

BMI:16.02 ± 3.4

-Group 2:

10 M/10F

6.0 ± 0.71y

10M/10F

BMI:20.98 ± 0.48

In-lab PSG (only in group 1)

-Epworth

sleepiness

scale

-Lateral

cephalogram

-Dental

measurements

on casts

6-months

Significant reduction of AHI.

Non-significant change of SaO2.

The median AHI score decreased from 7.88 to 3.66.

MM reduced daytime sleepiness, and the ESS score decreased from 15.2 ± 4.9 to 7.1 ± 2 after treatment.

Cozza et al. 2004 [17]

Cohort study

Class II malocclusion (mandible posterior to

the maxillary arch)

Upper jaw: Hyrax-type expander with embedded tube

Lower jaw:

removable acrylic plate connected.

with a 0.045 wire

Construction bite: mandibular

Maximal jumping-

Wearing time: night time only

(after upper expansion)

expansion: 1turn/day for 20 days; 2 turn/day for 10 days

Treated group.

Control group:

untreated

Treated group:

94 (16 from 6–7 years old; 38 from 7–8 years old and 40 from 8–9 years old)

Control group:

113(54 from 6–7 years old; 34 from 7–8 years old and 25 from 8–9 years old)

Treated group:

4.19–7.98y

Control group:

6-8.96y

PSG

9 ± 3 months

AHI was significantly reduced in 53% of the treated patient samples, below the pathological threshold (< 1), with a higher proportion in the youngest age group (63%). No positive evolution of respiratory symptoms of this OSAS was observed in the control group. The ODR decreased after the treatment only until the age of 7 years, but not significantly.

Remy et al. 2022 [18]

NRCT

Class II skeletal malocclusion associated with normal maxilla (SNA, 79° to 84°) and mandibular retrusion (SNB ≤ 76°).

An individual customized twin block was fabricated for

each patient. One-step mandibular advancement was performed during wax check-bite recording with an edge-to edge incisor relationship and a 3-mm opening between the maxillary and mandibular incisors. A midline expansion screw was incorporated in the upper part of the appliance if any crossbite or cusp-to-cusp relation of the posterior teeth was noted during bite registration. Maxillary expansion was performed when needed.

Study group: (AHI) > 1.0/h

twin-block treatment

Control group: (AHI < 1.0/h)

the control group received a phase of prejunctional therapy (sectional, fixed orthodontic appliance) to correct occlusal interferences.

- Study Group

34

- Control Group

34

- Study Group

10.29 ± 1.21y

29 M/18F

BMI:24.6 ± 2.7

- Control Group

10.42 ± 1.35y

29 M/18F

BMI:23.9 ± 2.4

PSG

CBCT (cone beam computed tomography)

9 months

At the end of treatment, the AHIs had dropped

significantly by 11.2 events/hour (P < 0.001).

Zreaqat et al. 2023 [19]

NRCT

Skeletal Class II due to retrognathic mandible (ANB of > 4°), narrow and constricted maxillary arch, Class II Division 1 malocclusion with full cusp molar relationship, overjet of 5–8 mm

Customized fixed intraoral rapid maxillary expansion with a twin-block mandibular advancement appliance. A bonded upper component consisted of rapid maxillary expander (RME) screw fixed in upper component of twin block and bonded lower component for mandibular advancement.

All patients underwent upper arch expansion using the Timms protocol (Two turns per day, one in the morning and one in the evening until the desired expansion was achieved)

Only cases with mild and moderate severity, as indicated by an AHI greater than 5 but less than 29 events/hour, were included in the study

22

11.7 ± 1.5y

10 F

BMI:34.12 ± 5.89

PSG

lateral cephalograms

CBCT

8 months

There was a significant improvement in AHI, events/hour, SpO2%,and sleep efficiency.

AHI decreases from 12.18 ± 2.6 to 9.8 ± 2.7

Nadir SpO2 (%) increases from 91.5 ± 8.2 to 97.6 ± 5.9

Mastud et al. 2024 [20]

NRCT

Class II malocclusion, with retrognathic mandible and narrow maxilla, high palate

ANB > 4°,SBN < 78°

Modified Twin-block

The sum of the vertical opening distance and the forward extension distance is about 8 mm. The angle between the locking plane of the orthodontic appliance and the He plane is 45 °. A spiral expansion spring is placed at the palatal seam of the upper part of the Twin block functional orthodontic appliance.

Stop expanding when the tongue tip of the upper molars is opposite the cheek tip of the lower molars (RME)

Group 1:

Adenoid and/

Or tonsillectomy

+modified twin-block treatment

Group2:

twin-block treatment

-Group 1:

10

-Group 2:

11

-Group 1:

10.3 ± 0.95y

5M/5F

BMI:15.38 ± 1.71

-Group 2:

10.18 ± 0.98y

5M/6F

BMI:15.20 ± 1.58

PSG

(ApneaLink Air)

cephalogram

questionnaire (OSA-18)

tonsil examination

Group1:

13.5-months

Group 2:

12.4 -months

After treatment, both AHI and OAI values of the two groups of patients decreased, while the lowest blood oxygen saturation increased, and the difference was statistically significant (P＜0.01), The total score of two OSA-18 groups decreased. All the change of group1 is greater