Orbital Compartment Stress Responses Related to Rapid Maxillary Expansion: A Finite Element Analysis

This study aimed to use finite element analysis to evaluate the effects of acrylic HYRAX and hybrid HYRAX devices in the treatment of rapid maxillary expansion (RME), particularly on the orbital compartments.

In the present study, a craniofacial model was developed utilizing computed tomography data obtained from the visible human project. A total of four distinct models were generated by designating the sutures in the adult variation as closed and those in the non-adult variation as open while incorporating both expansion devices into the model. Both acrylic and hybrid device models were subjected to expansion forces of 0.25 mm and 5 mm, yielding eight distinct scenarios for comprehensive analysis.

Significant stress and displacement were observed, particularly around the orbital compartments in all scenarios. Displacement decreased with increased sutural ossification and the resulting stresses demonstrated elevation. In adult models, the hybrid device generated reduced stress, especially around the orbital compartments.

Based on these findings, it is proposed that the orbital compartments may serve as a clinically relevant site for measuring the increased intracranial pressure during RME treatment. To prevent possible side effects, RME should be performed at an early age, and if ossification is suspected to be increased, bone-supported expansion devices are recommended.