Objectives : It is necessary to understand curing process of luting cements to achieve successful cementation of indirect dental restoration. In this study, curing process of three different kinds of resin-based luting cements were monitored utilizing dynamic small-amplitude oscillatory shear experiments. The purpose of this study was to investigate clinically relevant, quantitative methodology to characterize the working and setting times of luting cements.
Materials and methods : Three different types of resin-based luting cements (composite luting, dual-cured (A); self-adhesive, dual-cured (B); crown and bridge luting, self-cured (C)) were tested in this study. Samples were dispensed using dual syringe with mixing tip. 2 Hz oscillation frequency and 0.1–0.2% shear strain were applied with 8 mm stainless steel parallel plate using a rheometer (AR-2000ex, TA instruments). Time sweeps were performed to determine working time (at 23 °C) and setting time (at 37 °C). The working time was determined by time at initial slope change in tan δ . The setting time was determined by onset time of storage modulus. Working and setting times were also investigated using differential scanning calorimetry (DSC) (Q2000, TA Instruments) at 23 and 37 °C, respectively, for comparison.
|Formula A||Formula B||Formula C|
|Working time (minutes)||1.81 ± 0.04||4.40 ± 0.14||3.47 ± 0.14|
|Complex viscosity at working time (Pa s)||808.01 ± 59.21||366.93 ± 190.57||1405.40 ± 234.18|
|tan δ at setting time||0.45 ± 0.01||0.35 ± 0.06||0.59 ± 0.06|
|Setting time (minutes)||2.50 ± 0.37||4.87 ± 0.47||3.79 ± 0.16|