Figure 1: (a) Low magnification (×1000) image of sandblasted specimens showing crevice and cracks. Gross structural defects were noted (Group 1) (b). SIE infiltrated specimens with ultrastructural changes in the nanolevel. (Group 2) (c). Sandblasted and SIE/heat-induced maturation specimens (Group 5). SIE: Selective infiltration etching