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Retentive Force of Adjustable Dental Impression Trays with Different Synthetic Resin Materials In-Seob Lee, D.D.S., jin-Han Lee, D.D.S., M.S.D., Yu-Lee Kim, D.D.S., M.S.D., Jin-Keun Dong, D.D.S., M.S.D., Ph.D. Department of Prosthodontics, School of Dentistry, Wonkwang University The adjustable dental impression trays were made for being adjusted their width automatically along the width of patient’s dental arch. The purpose of this study was to investigate the retentive force of adjustable dental impression trays made of different synthetic resin materials. Three pairs of adjustable trays were made of ABS(acrylonitrile butadiene styrene) synthetic resin, polyurethane synthetic resin and polycarbonate synthetic resin with a hole and without a rim on the border area of them. The experiment was done with the horse-shoe shaped metal plate to pull out the set impression body from the tray jig which was made for holding the tray on the lower part of Universal Testing Machine(UTM, Zwick Z020, Zwick Co., Germany). After the alginate impression in the tray was allowed to set four minutes, a tensile force was applied at right angles to the tray which had been previously seated on the jig. The force was applied to measure a maximum force by use of UTM at a constant strain rate 100mm per minute. The results obtained in this study were as follows : 1.The upper trays were showed higher retentive force than lower trays in three tray materials. 2.There was no significant difference in the retentive force of the tray materials(p>0.05).
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