The similar to 90 degrees C endotherm peak in the thermogram of a conventional dental amalgam is due to two overlapping peritectic transitions involving SnHg-delta(2) and HgAgSn-gamma(1), respectively. The aim of the present study is to separate these two events and thus confirm that the delta(2) phase is indeed a part of an amalgam microstructure. The materials used in this study were : sample 1, gamma(1) + 1 wt % Sn; sample 2, gamma(1) + 2 wt % Sn; sample 3, gamma(1) + 3 wt % Sn; and sample 4, a commercial conventional amalgam with 48 wt % Hg. In powder form, they were exposed to 1 wt % NaCl solution at 37 degrees C for up to 45 days. At 15 day intervals, samples were withdrawn from the solution, washed, dried and then characterized by the differential scanning calorimetry (DSC) technique. Corrosion of Sn from ternary gamma(1) matrix and intergranular delta(2) in respective materials during their exposure to the NaCl solution led to the following : (a) a progressive increase in gamma(1) --> beta(1) transition temperature in samples 1 and 2; (b) a gradual decrease in delta(2) peak and its disappearance in sample 2; and (c) in samples 3 and 4, initial splitting of the similar to 90 degrees C peak into two distinct endotherms associated with delta(2) and gamma(1), respectively. Continued corrosion of the last two materials produced further changes in delta(2) and gamma(1) in a manner similar to that seen in samples 1 and 2. On the basis of these observations, we have concluded that the similar to 90 degrees C endotherm is a valid indicator of the existence of the delta(2) phase in dental amalgams.