The difference of stress distribution of maxillary expansion using rapid maxillary expander (RME) and maxillary skeletal expander (MSE)-a finite element analysis

Abstract

Background: Maxillary skeletal expander (MSE) in combination with miniscrews was developed to overcome the drawbacks that may have resulted from the application of conventional rapid maxillary expander (RME). This research was conducted to analyze the difference of stress distribution of maxillary expansion using RME and MSE in the region of interests (ROIs): first molars (M1), palatal alveolar bones of M1, palatine sutures, zygomatic sutures, miniscrews, and their surrounding bones.

Methods: A dry skull was scanned using CBCT and rendered into a three-dimensional (3D) model of craniomaxillary structures. The data analysis was done both visually and numerically.

Result: The stress distributions in RME group were located at the palatal side of M1, mesial side of palatal alveolar of M1, pulp chamber of M1, and inferior cortex of palatine sutures. The stress distributions in the MSE group were located at the distopalatal cusp of M1, palatal side of palatal alveolar of M1, and inferior and superior cortex of palatine sutures. The stress distributions in zygomatic sutures on both groups were located at the zygomaticotemporal sutures, whereas in the miniscrews, the stress were located at the anterior miniscrews and palatal side of surrounding bones.

Conclusions: There were significant differences of stress distribution of maxillary expansion measured in the ROIs in the craniomaxillary 3D model using RME and MSE.

Keywords: Finite element analysis (FEA); Maxillary skeletal expander (MSE); Rapid palatal expander (RME); Stress distribution.

Fig. 1

The von Mises stress distribution on the maxillary first molar in the expansion simulation using (a) RME, and (b) MSE

Fig. 2

The von Mises stress distribution on the palatal alveolar bone of upper first molar in the expansion simulation using (a) RME, and (b) MSE

Fig. 3

The von Mises stress distribution of the palatine suture in the expansion simulation using (a) RME, and (b) MSE

Fig. 4

The von Mises stress distribution of the zygomatic suture in the expansion simulation using (a) RME, and (b) MSE

Fig. 5

The stress distribution of the miniscrew in the expansion simulation using MSE

Fig. 6

The stress distribution of the palatal bone around miniscrew insertion site in the expansion simulation using MSE

Fig. 7

Frontal aspect of stress distribution as the resut of expansion of RME (a) and MSE (b)

Fig. 8

Lateral aspect of stress distribution as the resut of expansion of RME (a) and MSE (b)

Fig. 9

Occlusal aspect of stress distribution as the result of expansion of RME (a) and MSE (b)

Fig. 10

Cortical bone thickness dissimilarity on palatum