| 1 | Deepak et al.22 | 2014 | India | 137 pre- and post-ortho dental cast | Dental cast (Thomas and Kotze) | NA | Group 1: 50 extraction Group 2: 50 non-extraction Group 3: 37 cases of palatal expansion comprising both extraction and non-extraction* * Unsure types of expansion used | NA | Length - Insignificant changes for all three groups. Morphological shape - Insignificant changes |
| 2 | Ali et al.23 | 2016 | Pakistan | 168 pre- and post-ortho dental cast | Dental cast (Thomas and Kotze) | NA | Group 1: 58 subjects for extraction (all first premolars) Group 2: 58 subjects non-extraction Group 3 : 58 subjects palatal expansion (HAAS expander) with 1 turn of activation every alternate day to achieve 5mm expansion followed by non-extraction fixed appliance treatment | Exclusion: Prior history of orthodontic or prosthodontics treatment, history of any severe palatal trauma and congenital syndromes affecting the palate such as cleft palate or any surgical procedures performed on the hard palate were excluded. | Length - Second and third rugae in the extraction group were significantly reduced (p < 0.05). Statistically significant increase in the third rugae length was observed in the palatal expansion group (p < 0.05). No difference between left and right in extraction and non-extraction group No morphological change of all three groups |
| 3 | Bavaresco et al.19 | 2020 | Moscow | 30 patients | Photograph of dental cast (Santos classification) | > 18 years old | Group 1:10 subjects for HAAS expander followed by fixed appliance without extraction. Group 2: 1 0 subjects with extraction of upper first premolars followed by anterior retraction. Group 3: 1 0 subjects without extraction nor expansion | Inclusion: patient that had complete dental records in the archives of the local dental centre, underwent orthodontic treatment, had initial and final orthodontic dental casts, and older than 1 8 years of age. Exclusion: Orthodontic dental casts in poor condition, orthodontic dental casts in which the palatal rugae were not properly visible, patients with history of trauma in the maxillofacial region, patients with visible diseases in the soft and hard tissue of the palate, and patients with history of systemic diseases | Morphological change: Significant for expansion and extraction group but not for non-extraction group |
| 4 | Damstra et al.24 | 2009 | USA | 38 patients | Photograph of dental cast (LyseII classification) | Group 1 : 12.4 ± 2.0 Group 2: 12.5 ±2.1 | RME group: 19 patients RME followed by fixed appliance without extraction Control group: 19 patients with fixed appliance only | Inclusion criteria: RME Group -1 . Initial treatment by a Hyrax appliance (four banded in the permanent dentition, two banded with anterior expansion in the mixed dentition) 2. A minimum of 1 2 months of pre-adjusted full fixed appliance treatment following RME. 3. No extraction of maxillary premolars 4. Clear and identifiable rugae points on the dental casts. 5. Standardized Hyrax activation protocol (one activation of the screw per day) 6. A minimum of 5mm palatal screw activation Control group: 1 . No treatment with an expansion of any type of appliance (hyrax, quadhelix, headgear, or transpalatal arch) 2. A minimum of 1 2 months of pre-adjusted full fixed appliance treatment3. No extraction of maxillary premolars 4. Clear and identifiable rugae points on the dental casts | Measurement: Significant change of transverse measurement (TM) between medial aspect of the rugae but no change in anteroposterior measurement (APM) in RME group No change in TM and APM in control group |
| 5 | Lanteri et al.25 | 2020 | Italy | 54 subjects | 3D model (best of fit superimposition using RMS) | 8.5 ± 1.5 years old | Group 1: 27 subjects treated with Leave Expander Group 2: 27 subjects without treatment | Inclusion: Early or mid-mixed dentition, with both primary second molars (Es) preserved, Cervical Vertebral Stage 1 through 3 (CVS methods 1-3), Angle Class 1 or Class II malocclusion, no previous orthodontic treatment and maxillary arch constriction Exclusion: The presence of craniofacial abnormalities, previous extraction or surgical treatment, Angle Class III malocclusion, Temporomandibular Joint dysfunctions (TMJD), or caries of Es | Measurement: No difference of root mean square (RMS-square root of the arithmetic mean of the squares of the point-to-point distance between the areas with an identical coordinate system) between both groups |
| 6 | Ugolini et al.26 | 2021 | Italy | 38 Italian subjects (1 7 males and 21 females) | 3D model (best fit algorithm) | Group 1 : 8.2 ± 1.2 years Control group :7.9 ± 1.4 years | Group 1: 38 patients received RME Group 2 (control group): 26 patient - no treatment | Inclusion criteria: Angle Class 1 or Class II dental malocclusion with uni- or bilateral cross-bite and/or constricted maxilla and were selected before the pubertal peak (cervical vertebral maturation stage 1-3) Exclusion: Patients with previous orthodontic treatment, hypodontia in any quadrant excluding third molars, craniofacial syndromes, or cleft lip or palate were not considered for the study | RMS value of the RME group is statistically higher than the RMS value of control untreated groups |
