# Efficacy of Maximally Expansion with Clear Aligner in the Mixed Dentition: A Systematic Review
## 4 Discussion
### Interimolar Dentalveolar Width  
The difference of interimolar dentalveolar width at T0 and T1, which was calculated from the most prominent buccal bulge on the alveolus superior to the maxillary first molar, was statistically significant (\(p<0.05\)) in the IF group [9; 28; 29] and the RME group [28; 29], while they did not find a significant difference in the NG group [28; 29]. First and Second Interdeciduous Molar Width, First and Second Interpremolar Width, and First Interimolar Width  
[PERSON] et al. [30] measured upper inter first premolar (palatal cusp tip), upper inter second premolar (palatal cusp tip), upper inter first temporary molar (mesiopalatal cusp tip), upper inter second temporary molar (mesiopalatal cusp tip) and upper inter first permanent molar (mesiopalatal cusp tip) in patients treated with Invisalign(r) First between T0 and T1. They observed an increase in all these measurements, but they did not report the statistical significance. The studies included in the review demonstrated a significant increase in interac-nine width [1; 2; 7; 15; 18; 19; 25; 26; 27; 28; 29; 30] in patients treated with Invisalign(r) First clear aligners, like patients treated with rapid maxillary expander [1; 2; 19; 25; 28; 29], while no significance was found in NG group [19; 28; 29]. The studies by [PERSON] et al. [15; 26] and [PERSON] et al. [30] reported an increase in this parameter, but they do not specify whether this difference is statistically significant. It was registered also an improvement of intercanine transpalatal width [1; 2; 7; 15; 26], first and second interdeciduous molar width [7; 15; 26; 27; 28; 29; 30], first interpremolar width [28; 29; 30], intercanine dentoalveolar width [28; 29], first and second interdeciduous molar transpalatal width [7; 15; 19; 26], first intermal mesial width [1; 2; 7; 15; 18; 25; 26; 27; 28; 29], first intermal distal width [15; 18; 25; 26; 27; 25], first intermalmal transpalatal width [1; 2; 7; 15; 18; 26; 27; 30], first intermal width [30], inclination of the molars and arch perimeter [7; 28; 29], arch depth [7; 25; 28; 29], intermal dermatoalveolar width [9; 28; 29], and second interpremolar width [30]. From the analysis of the results, it emerged that the greatest increases were achieved at deciduous molars. Compared to the other teeth, the difference between the increases was minimal, therefore a near-parallel pattern of maxillary dental arch expansion was observed. The studies comparing treatment with Invisalign(r) First clear aligners and rapid maxillary [7; 15; 26; 27; 28; 29] expander highlighted that both determined statistically significant differences compared to NG group. [PERSON] et al. [11] represented graphically the changes of the maxillary arch after the treatment with Invisalign(r) First clear aligners and RME: the IF group presented an improvement in the maxillary arch shape, while the RME group maintained the initial triangular shape. Except for arch depth, [PERSON] et al. [1,2], [PERSON] et al. [28,29], [PERSON] et al. [30], [PERSON] et al. [19], and [PERSON] et al. [25] reported that RME allowed a greater expansion with larger increases in all width indicators compared to Invisalign(r) First, indicating that it may be a preferable option for severe malocclusions. [PERSON] et al. [15,26] also recorded a larger increase in first intermolar mesial, distal, and transpalatal width in patients with RME compared to Invisalign(r), but not for intercanine transpalatal width, first and second interdeciduous molar width, or first and second interdeciduous molar transpalatal width. Invisalign(r) First, a clear orthodontic system created especially for kids with mixed dentition, has been shown to be a creative and clinically effective way to treat transverse problems with the maxillary arch. By influencing the position of the teeth as well as the adaptation of the alveolar bone that supports them, it has demonstrated exceptional effectiveness in causing dentoalveolar extension of the upper arch.