Table 2 Characteristics of included studies

Morales-Burruezo et al., 2020 [18]

Retrospective study

114 participants; aged 18–75 years

-Efficacy for arch expansion (transverse distance variation) at the level of upper maxillary canine, first and second premolars, and first and second molars

-Efficacy for upper maxillary first molars rotation and inclination

-Predictability of ClinCheck® software movements’ previsions

ClinCheck® software (planned vs achieved)

Transverse expansion

-Canines (1.87 SD 1.78 mm, + 6.31%)

-First premolars (3.14 SD 2.25 mm, + 8.73%)

-Second premolars (3.45 SD 2.09 mm, + 8.42%)

-First molar (2.57 SD 1.83 mm, + 5.64%)

-Second molar (0.45 SD 1.83 mm, + 0.54%)

Inclination right first molar: 2.26 SD 4.76 mm

Inclination left first molar: 2.13 SD 4.09 mm

Rotation right first molar: 2.22 SD 4.37 mm

Rotation left first molar: 2.46 ± 3.75 mm

Predictability

-Intercanine distance: 0.63 SD 0.75 (74.8%)

-First premolar: 0.77 SD 1.44 mm (80.3%)

-Second premolar: 0.81 SD 1.26 mm (81.0%)

-First molar: 0.69 SD 1.21 mm (79.1%)

-Second molar: 0.25 SD 1.97 mm (65.2%)

-Inclination right first molar: − 0.42 SD 3.36 mm (123.5%)

-Inclination left first molar: − 0.88 SD 2.73 mm (170.4%)

-Rotation right first molar: 0.54 SD 3.05 mm (80.4%)

Rotation left first molar: − 0.34 SD 3.57 mm (115.3%)

Houle et al., 2017 [19]

Retrospective study

64 participants

Aged: 18–61 years (mean age 31.2 years)

Accuracy of transverse width measured at:

- Level of canine tip and gingival margin

-First premolar tip and gingival margin

-Second premolar tip and gingival margin

-First molar tip and gingival margin

ClinCheck® software (planned vs achieved)

Predictability of transverse expansion:

Upper arch-Canine tip: 0.22 SD 0.74 mm (88.7%)

-Canine gingival margin: 0.6 SD 1.02 mm (67.8%)

-First premolar tip: 0.58 SD 1.14 mm (84.7%)

-First premolar gingival margin: 1.09 SD 1.22 mm (67.6%)

-Second premolar tip: 0.75 SD 1.54 mm (81.7%)

-Second premolar gingival margin: 1.3 SD 1.61 mm (62.3%)

-First molar tip: 0.77 SD 1.84 mm (76.6%)

-First molar gingival margin: 1.43 SD 1.9 mm (52.9%)

Lower arch

-Canine tip: − 0.08 SD 0.81 mm (100%)

-Canine gingival margin: 0.65 SD 1.01 mm (61%)

-First premolar tip: 0.07 SD 0.96 mm (96.9%)

-First premolar gingival margin: 0.27 SD 1.00 mm (88.4%)

-Second premolar tip: 0.07 SD 1.15 mm (98.9%)

-Second premolar gingival margin: 0.38 SD 1.16 mm (85.5%)

-First molar tip: 0.03 SD 1.33 mm (100%)

-First molar gingival margin: 0.54 SD 1.34 mm (70.7%)

Krieger et al., 2012 [20]

Extended study based on previous pilot study

50 participants;

Aged 15–63 years (mean 33 SD 11.9)

Accuracy of:

-Upper/lower anterior arch length

-Intercanine distance

-Overjet

-Overbite

-Dental midline shift

-Irregularity index according to little

ClinCheck® software (planned vs achieved)

Little’s irregularity index:

-Upper dentition: from 5.39 SD 2.23 mm before treatment to 1.57 SD 0.98 mm post-treatment

-Lower dentition: from 5.96 SD 2.39 mm to 0.82 SD 0.50 mm

-Difference between clinically achieved and planned reduction of Little’s irregularity index was 0.04 SD 0.65 mm for the upper anterior arch and 0.01 SD 0.48 mm for the lower anterior arch

Upper inter-canine distance

From 33.51 SD 2.05 mm pre-treatment to 33.67 SD 2.00 mm post-treatment

-Difference between clinically achieved and planned upper intercanine distance variation was − 0.13 SD − 0.59

Lower inter-canine distance:

From 24.57 SD 1.69 mm to 25.27 SD 1.52 mm

Overjet

From 4.31 SD 1.43 mm to 2.94 SD 0.94 mm

-Overjet variation − 0.34 SD 0.54 mm

Overbite

From 4.05 SD 1.50 mm to 3.49 SD 1.19 mm

-Overbite variation − 0.71 SD 0.87 mm

Dental midline shift

From 1.38 SD 0.99 mm to 0.99 SD 0.89 mm

-Dental midline shift − 0.24 SD 0.46 mm

Lanteri et al. 2018 [14]

Retrospective study

200 participants

Aged 14–56 years

-Anterior dental crowding measured with little irregularity index or Peer Assessment Rating index (PAR)

Smart track aligners vs conventional fixed appliances

Invisalign

-63/100 (80.9%) fully resolved their anterior dental crowding and did not need any refinement

- PAR index: 22.5 SD 7 to 3.5 SD 3

- Maxillary Little Index

Pre-treatment 23% moderate/62% minimal

Post-treatment 100% perfect alignment

-Mandibular Little Index

Pre-treatment 12% severe/36% moderate/52% minimal

Post-treatment 92% perfect alignment/8% minimal

Treatment duration 14 SD 7 months

Conventional fixed appliance

- PAR index: 24.0 SD 6 to 4.5 SD 4

- Maxillary Little Index

Pre-treatment 31% moderate/69% minimal

Post-treatment 100% perfect alignment

-Mandibular Little Index

Pre-treatment 16% severe/32% moderate/52% minimal

Post-treatment 88% perfect alignment/12% minimal

Treatment duration 19 SD 4 months

Simon et al., 2014 [11]

Case–control (split mouth)

30 participants

Aged 13–72 years

Accuracy:

-Upper incisor torque > 10°

-Premolar derotation > 10°

-Upper molar distalization > 1.5 mm

Invisalign® with and without auxiliaries (attachments and staging)

Accuracy

Upper Incisor Torque > 10°

Invisalign with horizontal ellipsoid attachments vs Invisalign with power bridges:

51.5% SD 0.2 vs. 49.1%SD 0.2

Premolar derotation > 10°

Invisalign with optimized rotation attachment vs Invisalign without auxiliaries:

37.5% SD 0.3 vs. 42.4% SD 0.3

Upper molar distalization > 1.5 mm

Invisalign with horizontal beveled gingival attachment vs Invisalign without auxiliaries:

88.4% SD 0.3 vs. 86.9% SD 0.16

The overall accuracy

Upper incisor torque > 10°: 42%

Premolar derotation > 10°: 40%

Upper molar distalization > 1.5 mm: 87%

Zhou et al. 2020 [21]

Retrospective study

20 participants

Aged 20–45 years (mean 28.5 SD 6.3)

Accuracy of transverse width measured at:

- Level of canine tip

-First premolar tip

-Second premolar tip

-First molar tip

Maxillary basal bone width variations

Maxillary alveolar bone (buccal and palatal ridge crest) width variation

Difference of maxillary first molar tipping

ClinCheck® software (planned vs achieved)

Transverse expansion

-Canine 1.44 SD 0.60 mm

-First premolar 1.74 SD 0.84 mm

-Second premolar 1.57 SD 0.96 mm

Predictability of transverse expansion

-Canine tip: 0.33 SD 0.26 mm (79.75%)

-First premolar tips: 0.53 SD 0.45 mm (76.1%)

-Second premolar gingival: 0.65 SD 0.76 (73.3%)

-First molar tip 0.74 SD 0.73 (68.3%)

Difference in the basal bone width

0.04 SD 0.18 mm

Maxillary alveolar bone arch width

- Buccal ridge crest: 0.87 SD 0.63 mm

- Palatal ridge crest 0.75 SD 0.80 mm

Maxillary first molar tipping

2.07 SD 3.3

Solano-Mendoza et al., 2017 [22]

Retrospective study

116 participants

Mean age 36.6 (SD 11.5)

Accuracy of transverse width measured at:

- level of canine tip and gingival margin

-first premolar tip and gingival margin

-second premolar tip and gingival margin

-first molar tip and gingival margin

ClinCheck® software (planned vs achieved)

Predictability

-Canine tip: 94.2%

- Canine gingival margin: 76.5%

-First premolar tip: 89.7%

-First premolar gingival margin: 84.2%

-Second premolar tip: 92.1%

-Second premolar gingival margin: 88.9%

-First molar tip: 88.6%

-First molar gingival margin: 87.7%

Riede et al., 2021 [23]

Retrospective study

30 participants

Aged 13–50 years

Accuracy of expansion

ClinCheck® software (planned vs achieved)

Transverse expansion

-Canine tip: 0.4 SD 0.3 mm

-Canine gingival margin: 0.45 SD 0.3 mm

-First premolar tip: 0.5 SD 0.25 mm

-First premolar gingival margin: 0.4 SD 0.2 mm

-Second premolar tip: 0.5 SD 0.3 mm

-Second premolar gingival margin: 0.5 SD 0.45 mm

-First molar tip: 0.5 SD 0.35 mm

-First molar gingival margin: 0.5 SD 0.3 mm

-Distobuccal cusp tip in first and second molars

2.9 SD 1.9° and 2.9 SD 2.4°, respectively

Participants achieving the width variation planned by ClinCheck software for each site of the following upper maxillary teeth:

-Canine cusp (46.6%)

-Canine gingival margin (28.3%)

-First premolar cusp (41.7%)

- First premolar gingival margin (46.7%)

-Second premolar cusp (50%)

-Second premolar gingival margin (56.7%1)

- First molar cusp (40%)

-First molar gingival margin (50%)

Gu et al., 2017 [16]

Case–control

96 participants

Mean age

22.1 SD 7.9 and 26 SD 9.7

-Peer Assessment Rating (PAR) Index

-Treatment duration

Invisalign® vs conventional fixed appliances

-Both intervention and control groups achieved a statistically significant clinical improvement of PAR index (> 30% of score reduction)

-Fixed orthodontic appliance was better than Invisalign in resolving malocclusion based on PAR index scores

-Fixed orthodontic appliance was more effective than Invisalign in reducing the mean percentage of PAR index

-Invisalign treatment was faster than fixed orthodontic appliance: (13.35 vs 19.08 months)

Grünheid et al., 2017 [24]

Retrospective study

30 participants

Age 21.6 SD 9.8

Accuracy of:

-Mesial-distal

-Facial-lingual

- Occlusal-gingival

-Tip

-Torque

-Rotation

ClinCheck® software (planned vs achieved)

Accuracy

Mesial-distal

Maxilla

-Central incisor: − 0.06 SD 0.4 mm

-Lateral incisor: − 0.14 SD 0.39 mm

-Canine: − 0.11 SD 0.51 mm

-First premolar: 0.02 SD 0.47 mm

-Second premolar: 0.19 SD 0.65 mm

-First molar: 0.27 SD 0.30 mm

-Second molar: 0.07 SD 0.81

Mandible

-Central incisor: 0.12 SD 0.44 mm

-Lateral incisor: − 0.8 SD 0.62

-Canine: − 0.11 SD 0.72 mm

-First premolar: 0.02 SD 0.44 mm

-Second premolar: 0.13 SD 0.57 mm

-First molar 0.12 SD 0.34 mm

-Second molar 0.02 SD 0.50 mm

Facial-lingual

Maxilla

-Central incisor: − 0.45 SD 0.64 mm

-Lateral incisor: 0.01 SD 0.66 mm

-Canine: 0.11 SD 0.60 mm

-First premolar: 0.15 SD 0.53 mm

-Second premolar: 0.20 SD 0.63 mm

-First molar: 0.23 SD 0.62 mm

-Second molar: 0.30 SD 0.79

Mandible

-Central incisor: 0.11 SD 0.56 mm

-Lateral incisor: − 0.01 SD 0.51 mm

-Canine: − 0.26 SD 0.49 mm

-First premolar: 0.05 SD 0.62 mm

-Second premolar: 0.09 SD 0.59 mm

-First molar: − 0.08 SD 0.52 mm

-Second molar − 0.017 SD 0.39 mm

Occlusal-gingival

Maxilla

-Central incisor: − 0.30 SD 0.28 mm

-Lateral incisor: − 0.03 SD 0.26 mm

-Canine: − 0.02 SD 0.24 mm

-First premolar: 0.06 SD 0.19 mm

-Second premolar: 0.01 SD 0.22 mm

-First molar: − 0.02 SD 0.14 mm

-Second molar: − 0.13 SD 0.29 mm

Mandible

-Central incisor: − 0.14 SD 0.21 mm

-Lateral incisor: − 0.10 SD 0.22 mm

-Canine: − 0.01 SD 0.21 mm

-First premolar: 0.09 SD 0.24 mm

-Second premolar: 0.04 SD 0.21 mm

-First molar: − 0.01 SD 0.15 mm

-Second molar: 0.047 SD 0.16 mm

Tip

Maxilla

-Central incisor: − 0.42 SD 1.57°

-Lateral incisor: 0.35 SD 2.36°

-Canine: 0.31 SD 2.24°

-First premolar: − 0.18 SD 1.96°

-Second premolar: − 0.82 SD 3.63°

-First molar: − 1.06 SD 1.4°

-Second molar: 0.41 SD 5.18°

Mandible

-Central incisor: − 0.36 SD 1.81°

-Lateral incisor: 0.51 SD 2.75°

-Canine: 0.39 SD 3.11°

-First premolar: 0.16 SD 2.04°

-Second premolar: − 0.55 SD 2.55°

-First molar: − 0.38 SD 1.35°

-Second molar: 1.07 SD 3.06°

Torque

Maxilla

-Central incisor: 1.75 SD 2.86°

-Lateral incisor 0.08 SD 2.93°

-Canine: − 0.048 SD 2.55°

-First premolar: − 0.74 SD 2.40°

-Second premolar: − 1.18 SD 3.27°

-First molar: − 1.45 SD 2.37°

-Second molar: − 2.13 SD 4.19°

Mandible

-Central incisor: − 0.66 SD 2.61°

-Lateral incisor: − 0.29 SD 2.34°

-Canine: − 1.60 SD 2.04°

-First premolar: − 0.60 SD 2.53°

-Second premolar: − 0.74 SD 3.05°

-First molar: − 0.85 SD 2.41°

-Second molar: − 1.09 SD 2.13°

Rotation

Maxilla

-Central incisor: − 0.33 SD 2.80°

-Lateral incisor: 0.70 SD 3.23°

-Canine: 0.19 SD 2.31°

-First premolar: − 0.48 SD 1.48°

-Second premolar: − 0.70 SD 1.95°

-First molar: − 0.52 SD 1.58°

-Second molar: 0.06 SD 2.20°

Mandible

-Central incisor: − 0.60 SD 1.71°

-Lateral incisor: − 0.99 SD 2.28°

-Canine: 0.88 SD 3.14°

-First premolar: − 1.71 SD 2.91°

-Second premolar: − 0.88 SD 3.86°

-First molar: − 0.30 SD 1.07°

-Second molar 0.29 SD 2.66°

Statistically significant discrepancy with ClinCheck® prevision involves

-Upper central incisors (facial-lingual and occlusal-gingival movements)

-Upper second premolar and upper first molar (mesial-distal and facial-lingual movements)

-Upper second molar (occlusal-gingival movements)

-Lower central and lateral incisors (occlusal-gingival movements)

-Upper central incisor (torque)

-Upper first molar (tip and torque)

-Second lower premolar and molar (torque)

-Lower lateral incisor (rotation)

-Lower canine (torque and rotation)

-First and second lower premolars (rotation)

-Lower second molar (tip)

Houili et al., 2020 [12]

Prospective clinical study

38 participants

Mean age 36 years

Accuracy

-Mesial-distal crown tip

-Buccal-lingual crown tip

-Extrusion

-Intrusion

-Mesial-distal rotation

ClinCheck® software (planned vs achieved)

Accuracy

The mean accuracy of Invisalign for all tooth movements was 50%

-Rotation (46%)

-Buccal-lingual crown tip (56%)

-Mesial rotation of the mandibular first molar (28%)

-Intrusion of the maxillary central incisor (33%)

-Intrusion of the mandibular incisors (35%)

-Buccal crown tip of the maxillary second molar (35%)

-Distal rotation of the maxillary canine (37%)

-Extrusion of the mandibular second molar (37%)

-Distal crown tip of the mandibular second molar (50%)

-Intrusion of the mandibular second molar (51%)

-Mesial rotation of the maxillary canine (52%)

-Extrusion of the maxillary central incisor (56%)

-The lingual crown tip of the maxillary second molar (61%)

- Buccal crown tip of the maxillary second premolar (61%)

-Distal crown tip of the maxillary second molar (63%)

-Labial crown tip of the maxillary lateral incisor (70%)

-Buccal crown tip of the mandibular second premolar (70%)

Kassas et al., 2013 [17]

Retrospective study

31 participants

Mean age

35.2 ± 13.2 years

Model Grading System (MGS) of the American Board of Orthodontics:

-Alignment

-Marginal ridges

-Buccolingual inclination

-Occlusal contacts

-Occlusal relations

-Overjet

-Interproximal contacts

The mean scores of all of the MGS categories were improved after treatment, with the exceptions of the occlusal contacts and occlusal relationships categories

The improvements were statistically significant in scores:

-Alignment category: 15.16 SD 5.00 vs. 6.00 SD 3.78

-Buccolingual inclination category: 7.00 SD 3.14 vs. 6.26 SD 3.58

-Total MGS score: 45.03 SD 7.47 vs. 35.87 SD 9.36

Using the ABO criteria

-1 case (3%) received a passing score

-22 cases (71%) failed

-8 cases (26%) were considered borderline

Pavoni et al., 2011 [25]

40 participants

Mean age

Self-ligating 15 years

Mean age

Invisalign® Group 18 years

Transversal expansion:

-Intercanine width (lingual)

-Intercanine width (cusp)

-First interpremolar width (lingual)

-First interpremolar width (fossa)

-Second interpremolar width (lingual)

-Second interpremolar width (fossa)

-Intermolar width (lingual)

-Intermolar width (fossa)

-Arch depth

-Arch perimeter

Self-ligating vs Invisalign®

Self-ligating group

-Intercanine width (cusp) showed a significant increase from T1 to T2: 3.15 mm

-First interpremolar widths (lingual and cusp) had significant increases of 3.40 mm and 2.45 mm, respectively

-Second interpremolar widths (lingual and cusp), with significant increases of 2.50 mm and 2.15 mm, respectively

Invisalign® group

-Second interpremolar width at the fossa point (0.45 mm)

-Intermolar widths at the fossa (0.50 mm)

Significant difference was found between the 2 groups for the intercanine widths, the change at the cusp was significantly larger in the self-ligating group (2.65 mm)

The comparison between the two groups of the first interpremolar measurements showed an improvement in the self-ligating subjects significantly bigger at the lingual point (2.30 mm), and at the cusp (3.35 mm), similar to the second interpremolar widths (lingual and cusp), with a significant increase of 1.85 mm and 2.05 mm, respectively

Drake et al., 2012 [26]

Prospective single-center clinical trial

15 new participants (weekly aligner group)

-ΔU1(x) refers to the distance between lines drawn through the midpoint of the incisal edges of the superimposed target tooth perpendicular to the A-P axis (the plane of prescribed tooth movement)

- ΔU1(s) is the length of the line connecting the midpoint of the incisal edges of the superimposed target tooth

- ΔApex refers to the length of a line connecting the change in apex of the superimposed target tooth

- Rotation angle is the angle created by the intersection of lines drawn from the midpoint of the incisal edge to the apex of the target tooth. The apex of this angle is considered the center of rotation

- Tooth length refers to the distance from the midpoint of the incisal edge to the apex of the target tooth from the initial X-ray

- Crown length is the portion of the tooth length that is coronal to the bone

- Bone to C-rot. is the section of tooth length between the center of rotation and a line connecting the most coronal aspect of the faciolingual crestal bone

- ΔU1(o) refers to the A-P change in the midpoint of the superimposed incisal edge of the opposite central incisor, the one that was not the target tooth

- ΔU1(t) refers to the distance between the midpoint of the superimposed incisal edge of the contralateral central incisor, to the midpoint of the incisal edge of the target tooth

37 participants previously collected (biweekly aligner control group)

No overall difference in OTM (orthodontic tooth movement) was detected between the groups, with mean total OTM of 1.11 mm SD 0.30 and 1.07 mm SD 0.33 for the weekly aligner and biweekly control groups, respectively

Also, no difference was detected in the weekly OTM of the weekly aligner versus biweekly control groups overall (P = 0.812) or between any 2-week prescription cycle for the weekly aligner and biweekly control groups

However, 4.4 times more OTM occurred during the first week than the second week of aligner wear (P < 0.001) for the combined groups, considering all 2-week periods

Ravera et al., 2016 [15]

Multicenter retrospective study

20 participants

Mean age

29.73 years

Bodily maxillary molar distalization

ClinCheck® software (planned vs achieved)

Bodily distalization

-Upper first molar: 2.25 mm

-Upper second molar: 2.52 mm

Duncan et al., 2016 [27]

A retrospective chart review

61 participants

Arch Expansion

Interproximal reduction

Lowe incisor position and angulation

ClinCheck® software (planned vs achieved)

Differences in mean (T0-T1)

Mild crowding

OVJ: 0.73 mm

Moderate crowding

OVJ: 0.73 mm

OVB: 0.68 mm

Severe crowding

OVJ:1.32 mm

L1-NB: − 4.70°

L1-NB: − 1.55 mm

L1-MPA: − 3.94°

L1-APog: − 4.82°

L1-APog: − 1.74 mm

Grunheid et al., 2016 [28]

Retrospective cohort study

60 participants

Mean age

25/26 years

-Buccolingual inclination of the mandibular canines

-Intercanine distance

Invisalign® vs conventional fixed appliances

Difference (T2-T1)

Clear aligner

Inclination: 0.7 SD 2.5°

Distance: 0.7 SD 1.5 mm

Fixed appliance

Inclination: − 1.9 SD 5.1°

Distance: − 0.1 SD 2.4 mm

Khosravi et al., 2017 [13]

Retrospective study

120 participants:

-68 with a normal overbite

-40 with deepbite

-12 with openbite

Mean age

18 years or older

Overbite changes

No control group

Normal overbite

-Proclination of maxillary incisors (U1-NA): 0.7° and (L1-NB) 0.6°

- Anterior facial height: + 0.7 mm

-Mandibular plane angle: + 0.4°

Deep bite

-1.5-mm median opening of the overbite

-Proclination of the mandibular incisors and intrusion of the maxillary incisors

-Extrusion of mandibular first and second molars: 0.5 mm on average

-Proclination of the mandibular incisors was the main mechanism of bite opening

Open bite

-A median deepening of 1.5 mm

-Extrusion of the maxillary and mandibular incisors: (U1-PP) 0.9 mm and (L1-MP) 0.8 mm

Chisari et al., 2014 [29]

Prospective single-center clinical trial

30 participants

Ages

19 to 64 years old

Assessment of the impacts of age, sex, root length, bone levels, and bone quality on orthodontic tooth movement

No control group

-The rate of movement decreases from ages 18 to 35 years

-A slightly increasing rate from ages 35 to 50 and a decreasing rate from ages 50 to 70

-The correlation was significant between the percentage of the goal achieved and the cone-beam computed tomography superimposed linear measures of tooth movement

-A significant negative correlation was found between tooth movement and the measurement apex to the center of rotation, but bone quality, as measured by fractal dimension, was not correlated with movement

Hennessy et al., 2016 [30]

Prospective clinical trial

44 participants

Mean age

26.5 years SD 7.7

Mandibular incisor proclination

Invisalign® vs conventional fixed appliances

Mandibular incisor proclination

-Fixed appliances: 5.3° SD 4.3°

-Clear aligners: 3.4° SD 3.2°

Charalampakis et al., 2018 [10]

Retrospective study

20 subjects

Mean age

37 years

-Horizontal displacements

- Vertical displacements

- Intercanine and interpremolar widths

-Mesiodistal rotations

ClinCheck® software (planned vs achieved)

Horizontal displacements

Median difference (predicted-achieved)

-Maxillary central incisors horizontal (mm): 0.25

-Maxillary canines horizontal (mm): 0.20

Vertical displacements

Median difference (predicted-achieved)

-Maxillary central incisors intrusion (mm): 1.50

-Maxillary lateral incisors intrusion (mm): 1.10

- Mandibular incisors intrusion (mm): 0.80

-Mandibular canines vertical (mm): 0.30

-

Intercanine and interpremolar widths

Median difference (predicted-achieved)

-Maxillary intercanine width (mm): 0.45

Mesiodistal rotations

Median difference (predicted-achieved)

-Maxillary central incisors rotation (°): 2

- Maxillary lateral incisors rotation (°): 1.85

- Maxillary canines rotation (°): 3.05

- Maxillary premolars rotation (°): 0.90

- Mandibular incisors rotation (°): 1.85

- Mandibular canines rotation (°): 2.45

- Mandibular premolars rotation (°): 1.90

Buschang et al., 2015 [31]

Prospective clinical study

27 participants

No age indication

OGS scores:

-Alignment

-Marginal ridges

-Buccolingual inclination

-Occlusal contacts

-Occlusal relations

-Overjet

-Interproximal contacts

ClinCheck® software (planned vs achieved)

-Differences were greatest for alignment, marginal ridges, and occlusal contacts

-Differences for occlusal relations were also highly significant

Dai et al., 2019 [32]

Retrospective study

30 participants

Mean age

19.4 ± 6.3 years

First premolar extractions with Invisalign:

Achieved vs predicted movements of maxillary first molars and central incisors

ClinCheck® software (planned vs achieved)

Difference (predicted and achieved)

Central incisors

U1_Torque: − 5.16 SD 5.92°

U1_LLT: 2.12 SD 1.51 mm

U1_OGT: − 0.50 SD 1.17 mm

Maxillary first molars

U6_Angulation: 5.86 SD 3.51°

U6MC_MDT: 2.26 SD 1.58 mm

U6DC_ MDT: 2.31 SD 1.67 mm

U6MC_OGT: 0.61 SD 0.89 mm

U6DC_OGT: 0.01 SD 0.91 mm

Sfrondrini et al., 2018 [33]

Retrospective study

75 participants:

-25 aligners

-25 conventional fixed appliance

-25 self-ligating appliance

Control of upper incisor torque:

-11^SnaSnp

-11^Ocl

-I + TVL

Invisalign® vs

-Conventional fixed appliance

- Self-ligating appliance

11^SnaSnp

Conventional: 6.11° SD 3.91

Self-ligating: 5.64° SD 3.27

Aligner: 5.13° SD 3.23

11^Ocl

Conventional: 6.88° SD 4.28

Self-ligating: 5.17° SD 3.10

Aligner: 4.60° SD 3.46

I + TVL

Conventional: 1.56 mm SD 0.47

Self-ligating: 1.62 mm SD 0.66

Aligner: 1.47 mm SD 0.57