Table 2 Characteristics of the identified trials (n = 7)

Torres et al. [31] (2006)

University setting—Brazil

n = 60

E (crib and highpull chin cup): n = 30 (22F, 8M); 8.3 y (7–10.1 y)

C (no treatment): n = 30 (23F, 7M); 8.6 y (6.8–10.4 y)

(6–10 y)

Class I AOB

Non-extraction

No missing teeth or cross bite

Absence of oral habits and airway obstruction

Removable palatal crib: Adams clasps U6’s, labial bow, palatal crib, acrylic coverage

High pull chin cup: 450–550 g/side

14–16 h for 12 m

Pre- and post-TT lateral cephalograms

T 2– T 1 changes over time

34 skeletal, dentoalveolar and Soft tissue measurements

Duration of intrusion: 12 m

Skeletal

SNA (°), SNB (°), ANB (°), ALFH (mm), SN. GoGn (°)

Dentoalveolar

U6 Eruption (mm), L6 Eruption (mm), difference in eruption of molar (mm), overbite (mm), L6-GoMe (mm), L1-GoMe (mm), U6-PP (mm), U1-PP (mm), U1.NA (°),U1-NA (mm), L1.NB (°), L1-NB (mm), U6-FHp (mm), L6-FHp (mm), U1-FHp (mm), L1-FHp (mm), Expo U1 (mm), interincisor (°)

Soft tissue

H. NB (°),Nasolabial (°) mentolabial (°), Sn-ES (mm), Gl.Sn.P ′ (°), Sn-Gl vertical (mm), P ′ -Gl vertical (mm), LS-P ′ Sn (mm), LI-P ′ Sn (mm), soft AFH (mm), interlabial gap (mm)

Doshi et al. [28] (2010)

University setting—India

n = 20 (12F, 8 M); (8–15 y)

E1 (spring loaded bite block): n = 10 (5F, 5M)

E2 (magnetic bite block): n = 10 (7F, 3 M)

C: matched data from growth study (Human Growth Research Center, University of Montreal, Quebec)

AOB

Steep mandibular plane

Increased gonial angle

Increased lower anterior facial height

Class I or II

No finger-sucking habits or evidence of enlarged tonsils

Spring loaded Bite Block:

Woodside and Linder-Aronson

mandibular plate with occlusal acrylic resin block connected by buccal and lingual helical spring (0.9 mm SS), soldered to Adams clasps (0.8 mm SS)

Two, a 0.9-mm SS hook were placed buccally into the occlusal bite block in the molar region to measure the amount of activation

Activation: 250–300 cN/4 weeks

Magnetic Bite block:

Active vertical corrector (Dellinger)

Similar bite blocks to spring loaded, in each arch two circular (1.5*10.0 mm) neodymium iron boron magnets

Force applied to teeth: 300 cN

Full time wear

Pre- and post-TT lateral cephalograms

T2–T1 changes over time

34 (18 linear and 16 angular) measurements, superimpositions

EMG activity of the masseter and temporalis muscles

Duration of intrusion: 8 m

Retention: 10 m with passive block

Skeletal angular

SNA, SNB, ANB, Beta

Vertical angular

SN-GoGn, Ar-Go-Me, Ar-Go-N N-Go-Me, Gn/FH, SN/ANS-PNS, SN/UOP, SN/LOP, S-Ar-Go, SN/Go-Ar

Vertical linear

SN-ANS, SN-PNS, S-Go, N-Me, S-Go/N-Me

Dentoalveolar

UI-NA, LI-NB, UIE-NA LIE-NB,UIE-ANS-PNS, LIE-Go-Gn, UMC-ANS-PNS, LMC-Go-Gn, overjet, overbite

Soft tissue (mm)

Upper lip-S line, lower lip-S line

EMG

Mean changes in masseter and temporalis activity

Akl et al. [26, 27] (2020,2021)

University setting-Egypt

n = 20 (8–15 y)

C (200 g intrusive force with miniscrews): n = 10 (19.22 ± 1.45 y)

E (400 g intrusive force with miniscrews): n = 10 (18.95 ± 1.77 y)

Adult aged 18 to 25 y

Skeletal open bite

Dental open bite (3 to 8 mm)

Skeletal Class I/mild to moderate skeletal Class II

Normal incisal show

Non-extraction

No previous orthodontic treatment

Pre-intrusion: segmented fixed appliance on mx posterior teeth, Roth prescription

Intrusion phase:

4 mini-screws (10 × 1.6 mm; 3 M Unitek TAD): 2 infrazygomatic and 2 palatal between the 1st and 2nd M

Palatal wires and lower buccal stabilizing wires (0.9-mm wire bonded on the buccal surface)

closed nickel–titanium (Ni–Ti) coil springs

C: 200 g, E: 400 g

Recall: 2 weeks

–

Pre- and post-TT CBCT images

CBCT:

Mx teeth intrusion,

tipping of intruded teeth mesiodistally and buccolingually,

lower teeth extrusion,

root resorption: root lengths (cusp tip to the root apex of each root of all posterior teeth)

Clinically:

open bite closure/2 weeks

Duration of intrusion: 6 m

Intrusion measurements (mm) to FH for U4, U5, U6, U7

Mesio-distal tipping (°) relative to Frankfort Horizontal Plane (Tooth/FH) for U4, U5, U6, U7

Change in torque relative to mid-sagittal Plane (°) (Tooth/MSP) for U4, U5, U6, U7

Root length (mm) (1st and 2nd pm: B,P), (1st and 2nd M: MB,DB,P)

Open bite closure/2 weeks (clinically)

Hasan et al. [29] (2022)

University setting-Syria

n = 42 (26F, 16M); (8–10 y)

E1 (FPBB and LLLT): n = 14 (9F, 5M); (8.97 ± 0.58 y)

E2 (FPBB): n = 14 (8F, 6M); (9.02 ± 0.51 y)

C: (no TT): n = 14 (9F, 5M);

(9.87 ± 0.44 y)

Clinical:

8–10 y

Fully erupted incisors

Class I or Class II skeletal

1 mm AOB minimum

No previous orthodontic tt

lateral cephalograms:

(SN/Go Me) angle > 34°, MM-angle > 30°, and Björk sum > 40°

Two posterior acrylic bite blocks (at least 2 mm thickness), connected by TPA (4 mm away from palatal mucosa)

Tongue crib (0.9 mm SS wire)

Force: 250 g

Laser: Gallium aluminum arsenide (Ga-Al-As) laser with a continuous wavelength of 808 nm

Laser parameters: The power of 250 mW, the energy at 4 J, application time 16 s per point

Frequency of application: day 1, 3, 7, and 14 of the first month, then every 15 days until the end of the treatment

Full time wear

Pre- and post-TT lateral cephalograms

Recall: monthly

End of active TT: positive overbite 1–2 mm

Retention: posterior bite block and crib for 10 m

Duration of intrusion:

E1: (7.07 ± 1.54 m)

E2: (9.42 ± 2.31 m)

Clinical:

Time to correct AOB

Cephalometric:

Angular: SNA°, SNB°, ANB°, SN/MP°, PP-MP (MM)°, Björk Sum°, Y-axis°, U1/SN°, L1/MP°,

Linear (mm): S-Go, N-Me, S-Go/N-Me, U1-PP, U6-PP, L1-MP, L6-MP, overbite, overjet

Abellan et al. [25] (2021)

University setting-Spain

n = 20 (12F, 8M); (44.9 ± 9.6 y)

E (PBM and TAD based mx molar intrusion): n = 10

C (TAD based mx molar intrusion): n = 10

Extruded U6s without curved roots

Good oral hygiene

Permanent dentition with presence of adjacent teeth to the molar to be intruded

No previous trauma, orthodontic treatment or periodontal disease

Alveolar bone loss < 30%

No severe crowding in posterior teeth

Intrusion: 2 mini-screws (Jeil Corp, Seoul, Korea) 1.6 mm × 10 mm placed buccal mesial and palatal distal to the over erupted molar

Buttons were bonded buccal and lingual to molars

Elastic chains (75 g force) between the buttons and mini-screw

0.01 SS ligature tie between miniscews and molar after intrusion is completed

PBM: A low-power diode laser (Periowave; Ondine BioPharma, Vancouver,Canada) wavelength of 670 nm, with a power of 150 mW

–

Pre- and post-TT CBCT images

At days 0 and 180

Superimposed images using Dolphin software

3D models (STL) format obtained at 0, 90, and 180 days

On days 0, 1, 2, 3, 4, and 7 of the beginning of the intrusion and in each monthly follow-up

Duration of intrusion: 6 m

Periodontal parameters (probing depth and bleeding of probing)

Mean intruded distance (mm), intruded velocity mm/m at 3 m and 6 m

Resorption: mean molar volume at T0 and T2 (6 m)

Mousa et al. [30] (2021)

University setting-Syria

n = 40 (19F, 21M), (7.5–10.5 y)

E1 (OBB): n = 20, (8F, 12M), (8.8 ± 1.5 y)

E2 (RPBP/C): n = 20, (11F, 9M), (8.6 ± 1.1 y)

Clinical:

AOB 2–5 mm

7.5 to 10.5 y

Skeletal Class I or Class II

Tongue thrust

No airway issue or previous orthodontic TT

RPBP/C: Upper removable appliance with posterior bite plane (1–2 mm thickness)

OBB: posterior acrylic bite blocks, palatal bar (1.2 mm), to guide the tongue into a more posterior position. Labial bow (0.9 mm) to achieve a competent seal

Full time wear for 12 m

Retention: night time wear

Pre- and post-TT lateral cephalograms

9 angular and 8 linear measurements

Duration of intrusion: 12 m

Skeletal

Angular (°): SNA, SNB, ANB, MM, SN.GoMe, Björk

Linear (mm): S-Go, N-Me

Dentoalveolar

Angular (°): 1U.SN,1L. GoMe,1U.1L

Linear (mm): 1U-SPP, 6U-SPP,1L-GoMe, 6L-GoMe, OJ, OB

Hasan et al. [32] (2022)

University setting—Syria

n = 40 (19F, 21M)

E (RMI): n = 20, (10F, 10M), (9.7 ± 0.66y)

C (no TT): n = 20 (9F, 11M), (9.9 ± 0.54 y)

Clinical:

8–12 y (mixed dentition stage)

Skeletal AOB

Class I, II

Radiographic inclusion:

(SN/GoMe) > 33°

MM > 27° facial axis (Y-axis) > 65°

RMI: TPA and lingual arch. Nickle-titanium active springs attached to the tubes of upper and lower permanent first molars

Intrusion force: 800 g per side

Pulpotomy and occlusal reduction on primary molars were undertaken to reestablish occlusal contact

Full time wear

Pre- and post-TT lateral cephalograms

9 m apart

20 variables

Duration of intrusion: 9 m

Skeletal

SNA, SNB, SN/GoMe, MM, Björk Sum, Y axis, S-Go, N-Men,

Dentoalveolar

U1-PP, U6-PP, L6-MP, U1/SN, U1/L1, OB, OJ