Comparing the retention of two luting agents with the common core type materials

A major part of dental work is associated with fixed prosthodontics. The permanence of cemented restorations is based on different factors for instance, retention, appropriate cement and applying the correct way of use. The aim of this study was to compare the retention of zinc phosphate and polycarboxylate cements with the common core build up materials such as amalgam, composite, casting alloy and coremax II. Methods & Materials: In this experimental study twenty 6 6 mm cylinders were produced from every core build-up material. The teeth were prepared by means of mounting and cutting by high speed handpiece. To build – up a substitutionary crown cylinder, 100 cylinders were made by means of based metal casting alloy ingut with external diameter of 12 mm, height of 6 mm and a 6.1 mm hole in the center. 10 samples were cemented with zinc phosphate and the other 10 with polycarboxylate. The samples were placed under the dartec machine and the neccessary power for egress of piston from cylinder was measured by the dartec. The data were analyzed by SPSS software, factorial ANOVA and Duncan tests. The retention mean value of zincphosphate cement to casting alloy, Amalgam, Composite, Coremax II and the tooth sample was respectively as follows: 77±5, 71±5, 37±4, 32±2 & 24±2 MPa. The retention mean value of polycarboxylate cement to tooth, Amalgam, casting alloy, Composite and Coremax II was respectively as follows: 37±3, 32±6, 22±4, 10±1 & 8±1 MPa. ANOVA test demonstrated statistically significant differences between retention mean value of zinc phosphate and polycarboxylate cement with 5 core build-up materials (P<0.001). The reason of more retention in polycarbocylate cement to tooth structure can be related to chemical bonding between tooth and cement. The results of this study revealed that the casting alloy provided more retention than amalgam. The more retention of amalgam in comparison with composite and coremax II can be related to a more powerful compressive strength of amalgam.