Effect of Two Dentin Desensitizing Agents on the Retention of Cast Copings on Compromised Preparations Using Three Cements

Abstract

This study was designed to evaluate the effects of two dentin desensitizing agents on the retention of cast copings on compromised preparations using three cements. A total of 45 extracted intact human molars of approximately similar crown sizes were selected and mounted in epoxy resin blocks. They were designed to simulate all metal full coverage compromised crown preparation for a molar tooth, with occlusal convergence of 20o. An occlusal notch was prepared for exact repositioning of the copings during measurements. The Impressions of the prepared teeth were made with a vinyl polysiloxane impression material using plastic tubes and tray adhesive. The impressions poured using type IV dental stone. Wax patterns were made on stone dies with casting wax with flat occlusal surfaces and a consistent thickness. A round sprue wax shaped as a loop was attached to the center of the occlusal surface of each wax pattern parallel to the long axis of the prepared tooth to facilitate connection of the coping to the Universal testing machine. The test copings were cast with Ni-Cr base-metal alloy using an induction casting machine. Copings were recovered using airborne-particle abrasion.