Stress distribution and displacement by different bone-borne palatal expanders with micro-implants: a three-dimensional finite-element analysis

Abstract

The aim of this study was to analyze stress distribution and displacement of the maxilla and teeth according to different designs of bone-borne palatal expanders using micro-implants. A three-dimensional (3D) finite-element (FE) model of the craniofacial bones and maxillary teeth was obtained. Four designs of rapid maxillary expanders: one with micro-implants placed lateral to mid-palatal suture (type 1), the second at the palatal slope (type 2), the third as in type 1 with additional conventional Hyrax arms (type 3), and the fourth surgically assisted tooth-borne expander (type 4) were added to the FE models. Expanders were activated transversely for 0.25mm. Geometric nonlinear theory was applied to evaluate Von-Mises Stress distribution and displacement. All types exhibited downward displacement and demonstrated more horizontal movement in the posterior area. Type 3 showed the most transverse displacement. The rotational movement of dentoalveolar unit was larger in types 1 and 3, whereas it was relatively parallel in types 2 and 4. The stresses were concentrated around the micro-implants in types 1 and 3 only. Type 2 had the least stress concentrations around the anchorage and showed alveolar expansion without buccal inclination. It is recommended to apply temporary anchorage devices to the palatal slopes to support expanders for efficient treatment of maxillary transverse deficiency.

Nonsurgical miniscrew-assisted rapid maxillary expansion results in acceptable stability in young adults

“…The rigid structure of RMEs tends to induce parallel expansion of IMPW and IMW. 17,18 As a result, the premolars may be lingually relocated during alignment according to arch form. In addition, with increasing age, the amount of IPMW postexpansion change was large if the dentoalveolar changes were significant.…”

“…Gingival recession of , 0.21 mm to 0.52 mm was not clinically significant during orthodontic treatment with MARME, which was in accordance with the findings of Lin et al 11 Use of the miniscrew could distribute the stress throughout the palate, decreasing the concentration of the stress around the anchor teeth. 17 To overcome the retrospective nature of this study, all attempted cases were collected and followed regardless of the treatment outcome. In addition, measurement of the clinical crown height is an indirect quantification of buccal attachment loss, which does not directly reflect hard tissue attachment.…”

Camouflage treatment of skeletal Class III malocclusion with asymmetry using a bone-borne rapid maxillary expander

“…[13][14][15][16]23 To overcome these adverse effects, BBRME with skeletal anchorage has been reported. [17][18][19] The major advantage of BBRME is that it provides maximum skeletal and minimum dental effects, since the expansion forces can be directly applied to the basal bone and not to the teeth. 18,19 However, a previous study using finite element analysis reported that the treatment effects differed, depending on the type of expander and position of the mini-implants.…”

“…[13][14][15][16] To avoid these adverse effects, skeletal anchorage for rapid maxillary expansion has been reported. [17][18][19] This report presents the case of a patient with skeletal Class III malocclusion, transverse discrepancy, and facial asymmetry. The patient was successfully treated with a bone-borne rapid maxillary expander (BBRME), which was also used as indirect anchorage for Class III elastics.…”

Design optimization under uncertainties of a mesoscale implant in biological tissues using a probabilistic learning algorithm

“…The biomechanical aspects play an important role in the techniques related to implants in bones and many research have been per-formed, in particular by using experimental investigations and by developing computational mechanical models for understanding the aging and the implants stability as a function of the geometric shape and of the dimensions of implants (see for instance [2,4,9,17,19,32,37] and also [44,49,58,60,71,78,92,95]). Design optimization of implants in bone at macroscale by using deterministic computational models has also received increased attention (see for instance [36,43,50,53,56,74]).…”