Effects of miniscrew location on biomechanical performances of bone-borne rapid palatal expander to midpalatal suture: A finite element study

This study investigated the effects of miniscrew location on biomechanical performance of bone-borne rapid palatal expander (B-RPE) to midpalatal suture, using finite element (FE). Three cases of B-RPE with different miniscrew locations (3 and 6 mm from midpalatal suture and palatal interdental site) were simulated activations in partly ossified midpalatal suture maturation. This study compared the expansion amount and pattern along the suture line. Equivalent von Mises (EQV) stresses at appliance, miniscrew, midpalatal sutures, and elastic strain at the bone around miniscrew were evaluated. In all cases, they could not break the midpalatal suture of palatine bone. However, midpalatal suture at the maxilla was expanded. The expansion amount and unparallel expanding pattern were increased when miniscrews were positioned away from the suture. The interdental miniscrew position extended the suture more than the other 2 cases, but the pattern was unparallel. When the miniscrews were positioned away from the suture, the EQV stress at the appliance and elastic strain at the bone around the miniscrew were reduced. In the case of the palatal interdental miniscrew, all parameters were of lower magnitude. All cases could expand the partly ossified midpalatal suture maturation. The distance between the midpalatal suture and the miniscrew influenced appliance EQV stress, elastic strain at the bone around the miniscrew, and expansion characteristics.