Background and objectives: Micro-implant-assisted expanders have shown significant effects on the mid-face, including a degree of asymmetry. The aim of this study is to quantify the magnitude, parallelism, and asymmetry of this type of expansion in non-growing patients. Methods: A retrospective study on a sample of 31 non-growing patients with an average age of 20.4 years old, with cone beam computed tomography images taken before and right after expansion using maxillary skeletal expander (MSE) were assessed for skeletal expansion at three landmarks bilaterally. Results: Average magnitude of total expansion was 4.98 mm at the anterior nasal spine (ANS) and 4.77 mm at the posterior nasal spine (PNS) which showed statistical significance using a paired t test with p < 0.01. Average expansion at the PNS was 95% of that at the ANS. The sample was divided into symmetric (n = 15) and asymmetric (n = 16) based on the difference in expansion at the ANS, with 16 out of 31 patients exhibiting statistically significant asymmetry. Conclusions: MSE achieves distinctly parallel expansion in the sagittal plane but can exhibit asymmetrical expansion in the transverse plane.

Ney Paredes, Ausama Gargoum, Ramon Dominguez-Mompell, Ozge Colak, Joseph Bui, Tam Duong, Maya Giannetti, Fernanda Silva, Kendra Brooks, Won Moon,. Korean J Orthod 2023;53:289-97. https://doi.org/10.4041/kjod23.056

Andrew Combs, Ney Paredes, Ramon Dominguez-Mompell, Martin Romero-Maroto, Boshi Zhang, Islam Elkenawy, Luca Sfogliano, Layla Fijany, Ozge Colak, Ben Wu, Won Moon. Korean J Orthod 2024;54:59-68. https://doi.org/10.4041/kjod23.090

Background: To assess the changes in the inclination of the premolar and molar during a maxillary expansion with a micro-implant-assisted skeletal expander (MSE). Materials and Methods: A total of 21 patients (16 females, 5 males) with a mean age of 18.6 ± 4.5 (range 11.3–26.3 years) with a transverse maxillary deficiency were included in this study. They all received an MSE appliance for the maxillary skeletal expansion. The activation protocol consisted of about 0.5 mm expansion a day until a diastema was observed and continued with about 0.25 mm a day until the desired transverse relationship between the maxilla and mandible was achieved. OnDemand3D software was used for the measurements of the inclination change in the maxillary premolars and molars, pre- and post-expansion. Graphpad was used to compare the mean change in each tooth with the zero value (no change), and the p values of these changes with every tooth were calculated. Moreover, the changes and the mean values of all the teeth on the left and right sides were calculated separately. Results: A total of sixteen measurements were conducted for each patient. The first premolars tipped palatally after the expansion, while the second premolars and molars tipped buccally. The changes were significant for the molars and the left second premolar. Conclusions: The MSE induced some changes in the tooth inclination. The first premolars moved palatally, most likely due to perioral musculature and mastication force, while the first and second molars moved buccally. The second molar buccal movement is most likely due to the craniofacial rotation caused by the MSE as they were not subject to the expansion force.

Objectives: To investigate the prevalence of posterior tongue tie in orthodontic patients using numerical and clinical assessment methods in order to identify an association between posterior tongue tie and transverse maxillary deficiency. Materials and methods: Seventy-nine participants from an orthodontic clinic were divided into two groups. The first group of 44 patients exhibited a skeletally narrow maxilla and required maxillary skeletal expansion (MSE group) and 35 patients without a transverse discrepancy comprised a control group. Posterior tongue tie was examined by the Kotlow tongue tie classification, tongue range of motion ratio (TRMR) and via a clinical assessment. The prevalence of posterior tongue tie was compared between the two groups. Results: There was no significant difference in the level of the Kotlow classification grade between the two groups ( p > 0.05) and the overall majority was diagnosed as normal. However, a higher proportion of posterior tongue tie was found in the MSE group than in the control group by clinical assessment (MSE group, 72.7%; control group, 42.9%; p = 0.005). The proportion of TRMR grade 2 was also higher in the MSE group than in the control group ( p = 0.001). Of the subjects diagnosed with posterior tongue tie by clinical findings, approximately 94% showed TRMR grades 2 or 3. Conclusions: A clinical assessment of posterior tongue tie was found to be simple and accurate, whereas a numerical assessment alone provided diagnostic difficulty. Considering the high prevalence of observed posterior tongue tie in the MSE group, there was a significant association between posterior tongue tie and transverse maxillary deficiency.