A comparison of stress relaxation in temporary and permanent luting cements

The stress relaxation and compressive strength of resin, resin-modified glass ionomer, glass ionomer, polycarboxylate, and zinc oxide eugenol cements were measured to determine the characteristics of these materials after setting.

A total of 19 luting cements including 12 permanent cements and 7 temporary cements were used. Cylindrical cement specimens (10mm long and 6mm in diameter) were obtained by chemical setting or light curing. The specimens were stored for 24-36 h in water at 37°C and were then used for the stress relaxation and compression tests. The stress relaxation test was carried out using three constant cross-head speeds of 5, 50, and 100 mm/min. Upon reaching the preset dislocation of 0.5 mm, the cross-head movement was stopped, and the load was recorded for 60s. Fractional stress loss at 1s was calculated from the relaxation curves. The compressive strength and modulus were measured at a cross-head speed of 1mm/min. Data were analyzed with the Kruskal-Wallis test and Holm's test.

A zinc oxide eugenol cement [TempBOND NX] exhibited the largest fractional stress loss. A resin cement [ResiCem] showed the largest compressive strength, while a glass ionomer cement [HY-BOND GLASIONOMER CX] showed the largest compressive modulus among all tested cements (p<0.05).

The fractional stress loss could not be classified by the cement type. Two implant cements [Multilink Implant and IP Temp Cement] showed similar properties with permanent resin cements and temporary glass ionomer cements, respectively. Careful consideration of the choice of cement is necessary.