Evaluation of the retentive means, opacifiers and veneering materials for veneered crowns using 137 Cs

The purpose of this investigation is to evaluate the best plastic veneering material, which affords initial sealing and adaptation to the metal backing. Cs chloride is used for this purpose. The effect of different retentive means, namely, under cuts, wire loops, stainless steel grills, and acrylic beads, as well as the effect of different opaquers were studied. The influence of time factor and changing temperature was considered as well. The results obtained showed the following: 1- A quantitative method for the evaluation of micro leakage is essential parallel to the semiquantitative one. 2- The tested opaquer exhibits a better sealing ability. 3- The leakage increases significantly by temperature cycling, and by time duration with all the veneering materials tested. Composite is the least leak-sensitive material to changes in temperature. 4- Beads offered the best means of retention, to obtain the best sealing qualities.1 tab., 2 fig