A radionuclidic model for evaluating sealability of retrograde filling materials

Abstract

Radionuclidic technique was used to evaluate marginal sealing of five dental materials used for retrograde fillings. To determine whether dimensional changes occur during restorations, 130 human teeth were extracted, debrided, apicoectomized and filled retrogradely. The filling materials tested were Amalgam, Cavit-W, Duralon, zinc-phosphate cement and Restodent. 10 μCi 22Na were injected into each root canal before sealing it and coating the teeth completely, except for the filling area. Perspex was found to be superior to other coating materials tested. In addition, 50 perspex blocks were injected with 22Na, and sealed with the tested filling materials. Each tooth and perspex block was shaken in 10 mL medium, in which radioisotope infiltration was counted periodically for 6 months. Restodent, a composite acrylic filler, demonstrated the least leakage in both models, with zinc-phosphate cement the second best. Duralon and Cavit-W allowed greater leakage, while Amalgam seal was the worst. The high yield of the counting equipment, the small size of the radiosodium ion and the homogenicity of the perspex model compromises the use of 10 blocks for each test group. This study suggests the use of the perspex model instead of teeth for studies on sealability of sealing materials. Such studies may assist in the successful selection of retrograde fillers, thus reducing failures of retrograde filling procedures.