Figure. (a) Volumetric shrinkage strain and (b) axial shrinkage stress development (— measured, Maxwell model) of experimental resin composites (C-factor = 0.5) during curing. The onset in shrinkage stress (= gel-point) for the 30, 50, and 70 wt% TEGDMA composites was 192, 180, and 190 sec, respectively. Error bars indicate the standard deviations of the calculated mean (n = 3).