Figure 3. Representative TEM photomicrographs and SEM fractographs of the RMGI restorative applied to dentin. (A1,A2) Non-demineralized and unstained specimens of the exp-SE group revealing a thin, 0.5-µm, hybrid layer, absence of the gel-phase, and heterogeneously distributed hydroxyapatite crystals within the hybrid layer. (A3) Fractured dentin side after µTBS testing, showing cohesive failure in RMGI. (B1,B2) Non-demineralized and unstained specimens of the phosphoric acid group, unveiling a 5-µm-thick hybrid layer and absence of the gel-phase or hydroxyapatite crystals within the hybrid layer. (B3) Fractured dentin side after µTBS testing, showing cohesive failure in RMGI. Unaffected dentin (Ud); dentin tubule (T); hybrid layer (Hy); matrix in RMGI (M); glass particle in RMGI (Gp).