Evaluation of the appliances used in maxillary expansion in the mixed dentition period to the maxillary primary first molar tooth second molar tooth and permanent first molar with finite element analysis

A posterior crossbite occurs when the upper and lower jaws do not match in the transversal direction due to genetics, environmental factors or habitual behavior. If posterior crossbite is caused by maxillary stenosis, it can be corrected by the use of maxillary expansion appliances during the primary or mixed dentition. Although the mixed dentition is the most ideal time for maxillary expansion, this is also the time when tooth loss is most common. The aim of maxillary expansion is to achieve sutural opening rather than tipping of the supporting teeth. The aim of this study is to evaluate the extent of displacement of the supporting teeth as a result of the forces acting on the teeth when a slow maxillary expansion appliance is used in the maxilla in different scenarios with different teeth in the mouth by performing a three-dimensional finite element analysis and to determine in which scenario the undesirable displacement of the supporting teeth is less in children undergoing slow maxillary expansion treatment in the mixed dentition. In the present study, with a cone-beam computed tomography image of a child in the mixed dentition period with maxillary stenosis; to be grouped as having only permanent first molars (scenario one), permanent first and primary second molars (scenario two), permanent first and primary first molars (scenario three), permanent first, primary first, and primary second molars (scenario four) present 4 different scenarios were created. And, the displacements of the slow expansion appliance on the abutment teeth were evaluated comparatively. When evaluating the results of our study, most displacement occurred in the primary 2nd molar in the second scenario. This was followed by the primary second molar in the fourth scenario, the first permanent molar in the first scenario and the first permanent molar in the third scenario. It was concluded that when all teeth are present in the mouth, the displacement caused by the forces on the supporting teeth occurs to a similar extent in all supporting teeth and does not increase in any one tooth.