Stress and displacement pattern evaluation using two different palatal expanders in unilateral cleft lip and palate: a three-dimensional finite element analysis

Abstract

Background: In this finite element (FE) study, the stress distribution and displacement pattern was evaluated in the mid-palatal area and around circum-maxillary sutures exerted by bone-borne palatal expander (BBPE) in comparison with conventional HYRAX rapid palatal expander in unilateral cleft lip and palate.

Methods: Computed tomography scan images of a patient with unilateral cleft palate was used to create a FE model of the maxillary bone along with circum-maxillary sutures. A three-dimensional model of the conventional HYRAX (Hygienic Rapid Expander) expander and custom-made BBPE was created by laser scanning and programmed into the FE model.

Results: With the BBPE, the maximum stress was observed at the implant insertion site, whereas with the conventional HYRAX expander, it was at the dentition level. Among the circum-maxillary sutures, the zygomaticomaxillary suture experienced maximum stress followed by the zygomaticotemporal and nasomaxillary sutures. Displacement in the X-axis (transverse) was highest on the cleft side, and in the Y-axis (antero-posterior), it was highest in the posterior region in the BBPE.

Conclusions: The total displacement was observed maximum in the mid-palatal cleft area in the BBPE, and it produced true skeletal expansion at the alveolar level without any dental tipping when compared with the conventional HYRAX expander.

Keywords: Cleft lip and palate; Finite element method; Microimplant; Rapid palatal expansion.

Fig. 1

Three-dimensional model of a conventional HYRAX expander and b bone-borne palatal expander

Fig. 2

Von Mises stress distribution for the bone-borne HYRAX expander around the a mid-palatal suture area, b pre-maxillary region, c left palatal slope and d right palatal slope

Fig. 3

Von Mises stress distribution for the conventional HYRAX expander around the a mid-palatal suture area, b pre-maxillary region, c left palatal slope and d right palatal slope

Fig. 4

Von Mises stress fields around the circum-maxillary sutures in the a conventional HYRAX expander and b bone-borne HYRAX expander (a1, b1, zygomaticomaxillary suture non-cleft side; a2, b2, zygomaticomaxillary suture cleft side; a3, b3, nasomaxillary suture; a4, b4, zygomaticotemporal suture non-cleft side; and a5, b5, zygomaticotemporal suture cleft side)

Fig. 5

Displacement pattern in the X-axis for the a conventional HYRAX expander and b bone-borne HYRAX expander (a1, b1, non-cleft side; a2, b2, cleft side; a3, b3, frontal view; a4, b4, left palatal slope; a5, b5, right palatal slope; and a6, b6, mid-palatal area)

Fig. 6

Displacement pattern in the Y-axis for the a conventional HYRAX expander and b bone-borne HYRAX expander (a1, b1, non-cleft side; a2, b2, cleft side; a3, b3, frontal view; a4, b4, left palatal slope; a5, b5, right palatal slope; and a6, b6, mid-palatal area)

Fig. 7

Displacement pattern in the Z-axis for the a conventional HYRAX expander and b bone-borne HYRAX expander (a1, b1, non-cleft side; a2, b2, cleft side; a3, b3, frontal view; a4, b4, left palatal slope; a5, b5, right palatal slope; and a6, b6, mid-palatal area)