Linear dimensional changes of three luting agents

The linear dimensional changes during setting of a reinforced zinc oxide eugenol cement (Alumina EBA Crown and Bridge Cement), a composite resin cement (Epoxylite 9080 Crown and Bridge Adhesive) and a zinc silico phosphate cement (Fluoro-Thin cement), have been studied. The measurements were were performed on specimens placed on a mercury bath. The cements were allowed to set under various environmental humidity. The measurements of specimen length started 3 or 5 min after commencing the mix. The EBA-cement showed a maximum contraction of 0-4 percent after 7 days when setting under dry conditions. Under wet conditions the cement had an initial contraction the first day of setting, and thereafter an expansion. After 21 days specimens setting under 100 percent relative humidity showed 0-3 percent expansion, whereas specimens immersed in water attained the initial length. The composite resin cement showed a contraction of 1-0 percent after 1 day when setting under dry conditions. Under wet conditions the specimens had an initial contraction of 0-8 percent the first day of setting being reduced to 0-4 percent during the next 20 days. The zinc silico phosphate cement showed a maximum contraction of 3-0 percent after 7 days under dry conditions and 0-5 percent after 1 day under wet conditions.