Table 1 Summary of cases included in this review

Sohn 2008 [10]

Direct

Transverse

Lingually tilted #47

Buccal alveolar bone of #47

1.4 × 6 mm

Lower medium

Park 2002 [12]

Direct

Sagittal and transverse

Mesially and lingually tipped #47 (crossbite)

Retromolar area (distobuccally, 10 mm from the distal surface of #47)

1.2 × 6 mm

Lower medium

Direct

Sagittal

Mesially tipped lower second molar

Retromolar area

1.2 × 8 mm

Lower medium

Park 2004 [28]

Direct

Transverse

#37 and #27 in crossbite

1) Palatally between #26 and #27

2) Mandibular alveolar bone, buccal to #37

Both: 30–40° to the long axes of teeth

1.2 × 10 in the maxillary alveolar bone and 1.2 × 6 in the mandibular alveolar bone

Lower medium

Gracco 2007 [1]

Direct

Sagittal

Mesially inclined #37

MI was inserted manually through the buccal hole of the steel plate, which provided the most perpendicular positioning of the bayonet and tube

Length of 11 mm, head height of 2.25 mm, diameter of 0.8 mm at the tip and 1.25 mm at the head

Lower medium

Lee 2007 [4]

Direct

Sagittal

Mesially angulated 47 (locked)

Mesially, in the buccal alveolus between #46 and #45

1.8 × 7 mm

Lower medium

Direct

Sagittal

Mesially impacted #37

Mesially, in the buccal alveolus between #36 and #35 (in the 2nd phase: between #35 and #34

No information

Lower medium

Direct

Sagittal

Mesially impacted #47

Retromolar area

No information

Lower medium

Celebi 2011 [29]

Direct

Sagittal and transverse and vertical

#37 was mesially tipped and obliquely impacted under the distal bulge of #36

Buccal side between the first and second maxillary left molar’s roots

1.8 × 8 mm

Upper medium

Allgayer 2013 [5]

Direct

Sagittal

Mesially tipped lower second molars

Retromolar area

2 × 9 mm

Lower medium

Derton 2012 [15]

Direct

Sagittal

Mesially tipped first molar

Retromolar area

2 × 9 mm

Lower medium

Direct

Sagittal

Third molar

Two mini-implants mesially to the molar

2 × 9 and 1.5 × 8 mm

Lower medium

Yun 2005 [13]

Indirect

Sagittal

Mesially tipped and partially impacted the second molar

Between the mandibular right second premolar and first molar

No information

Low

Lee 2009 [27]

Direct

Sagittal

Second mandibular molar

Between the right canine and the 1st premolar

No information

Upper medium

Nienkemper 2013 [26]

Direct

Sagittal

Mesially tipped #37

Perpendicular to the edentulous alveolar ridge

2 × 11 mm

Lower medium

Direct

Sagittal

Mesially tipped #47

Perpendicular to the edentulous alveolar ridge

2 × 11 mm

Lower medium

Giancotti 2004 [3]

Direct

Sagittal

Deeply impacted #37 (with overerupted #38)

Retromolar area

2.3 × 7 mm

Low

Sivolella 2012^* [23]

Direct

Sagittal

Mesially impacted #47

Retromolar area

2 × 12 mm

Lower medium

Musilli 2010 [2]

Direct

Sagittal

Mesially tipped #37

Retromolar area

No information

Low

Direct

Sagittal

Mesially tipped #37

Retromolar area

No information

Low

Indirect

Sagittal

Mesially tipped#37 and #46

Mesial to the molars (it is not mentioned if they were placed perpendicular to the alveolar ridge or obliquely and it is not clear from the pictures)

No information

Low

Greco 2012 [25]

Direct

Sagittal

Mesially inclined #37

Retromolar area

1.3 × 12 mm

Lower medium

Melo 2013 [31]

65 MIs direct 116 MIs indirect

Vertically positioned on the alveolar crest or perpendicular to the buccal face of the alveolar bone

7, 9, or 11 mm in length and 1.3 or 1.6 mm in diameter

Padmaprabha 2015 [30]

Direct

Transverse and vertical

Lingually tipped and supraerupted #46

In the interradicular region of #46

1.2 × 6 mm

Upper medium