Finite element analysis on the effect of the incorporation of miniscrews in palatal expanders

Dept. of Dental Science/박사In adults, because of increased resistance from bony palate and zygomatic buttress many clinicians have adjudged surgically assisted RPE(SARPE) is a treatment choice. Because of several limitations of SARPE such as economic problem, surgical morbidity, needs of two stage surgery and complexity of treatment process, there have been several efforts to reduce surgical risks for young adults who have transverse deficiency. However, the effect and stress distribution of various devices, conventional RPE, bone-borne RPE and MARPE in young adults is not yet clearly understood. Therefore, the purpose of this study was to evaluate the stress distribution and displacement of various craniofacial structures after nonsurgical RPE in young adults according to the appliance design, the position and the number of miniscrews, using 3-dimensional finite element study.1. Conventional RPE induced the highest stress, although the maximum stress was on the frontal process of the maxilla and around the anchor teeth and not on the suture area. As the combination type of bone- and tooth-borne RPE, MARPE showed a relatively even stress distribution and reduced stress on the buccal plate of the anchor teeth. Bone-borne RPE was expected to be the most effective as an alternative of SARPE. However, the stress was highly concentrated around the miniscrews, rather than being transferred to the basal bone and the whole midpalatal suture.2. Even when 2 or 4 miniscrews were added to the bone-bone RPE, the stress remained extremely concentrated around the miniscrews, and the expansion force was not transferred to the basal bone under any condition.3. With both the bone-borne RPE and MARPE with 4 miniscrews, the stress was more evenly distributed and the maximum stress value was decreased when the miniscrews were located on the lateral palatal slope compared to when they were located in the midpalatal area.ope