Three-dimensional evaluation of maxillary sinus volume following the use of different designs of rapid maxillary expander: A comparative study

Aim of the study: to assess maxillary sinus volume changes (MSV) in adolescent patients with class III malocclusion after application of three types of rapid maxillary expanders (RME). Material and Methods: This was a prospective cohort study that recruited adolescent (13-17 years old) class III malocclusion patients with maxillary deficiency. Patients were randomly assigned to three study groups according to the type of RME: Conventional hyrax (CH), hybrid hyrax (HH), and maxillary skeletal expanders (MSE). Cone-beam computed tomography (CBCT) was used to measure MSV prior to and 6 months after application of RME. Measurements were compared between right and left sides and within study groups. P-values of less than 0.05 were considered significant. Results: A total of 51 patients (30 girls and 21 boys) were included. Mean ages were 14.89±1.6, 15.31±1.73, and 15.59±1.9 Y in the CH, HH and MSE groups respectively. Measurements in all groups were significantly increased. In CH and MSE groups, there was no significant difference between the right and left side before treatment (P =0.386).  But in HH, both before and after treatment, the right side values were considerably greater than the left side value (P≤0.05)

Changes in digital cast measurements related with two types of rapid maxillary expanders, tooth-borne versus hybrid one: A retrospective cohort study

Objectives: This study compared digital study casts from tooth-borne and hybrid Rapid Maxillary Expansion (RME) using 3D virtual models scanned with a 3Shape laser scanner. Methods: A total of thirty patients with narrow maxilla were distributed into two equal groups using sequential randomization. The hybrid hyrax group (11 females and 4 males) had a mean age of 14.5 years, whereas the conventional hyrax group (10 females and 5 males) had a mean age of 13.96 years. Cone beam computed tomography and orthodontic casts were obtained before expansion and six months after the last activation. Eight parameters were measured, and the data was analyzed. Results: A paired t-test was used to evaluate the mean differences between pre-expansion and post-expansion measurements. Interdental distance (IDD) and rotations at first molar and premolars showed a statistically significant increase post-treatment compared to preoperative values, whereas arch depth and incisor inclination showed a statistically significant decrease. Furthermore, group B had statistically significant higher postoperative values and a greater IDD change (P≤0.05). Conclusion: RME with hybrid hyrax achieved skeletal effects and broaden the arch with only a slight increase in IDD compared to traditional RME. Regardless of the appliance, arch depth may be decreased following RME