TEM images of the samples after demineralization (A; DE), demineralization in the presence of PI (B; DEpi), demineralization followed by remineralization (C; DE-REM), demineralization followed by remineralization in the presence of PI (D; DE-REMpi), and demineralization in the presence of PI followed by remineralization in the presence of PI (E; DEpi-REMpi). Before PILP-treatment showing the collagenous matrix at the acid-etch outer lesion sites (open arrowhead) was severely demineralized but contained sparsely arranged crystallites (pointers). In the DEpi group, the effect of demineralization decreases and the outer lesion sites had a higher electron density (asterisk) compared with that of the DE group. After PILP-treatment, regardless in the presence or absence of PI, showing electron-dense intrafibrillar and/or extrafibrillar apatite crystals, which were deposited within collagen scaffold. E = Epoxy resin.