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Figure 1. Radiographs and TEM micrographs of the primary molars that were retrieved from the first clinical subject. C, resin composite; A, adhesive; H, hybrid layer; D, dentin. Class I restorations with circumferential enamel cavosurface margins were placed with Single Bond as the dentin adhesive. In the control group (a,c,e), the adhesive was applied to phosphoric-acid-etched dentin. In the experimental group (b,d,f), 2% chlorhexidine was applied to the phosphoric-acid-etched dentin before the use of Single Bond. (a) Bitewing radiograph showing the Class I restoration in tooth 55 (control, circled). (b) Bitewing radiograph showing the Class I restoration in tooth 65 (experimental, circled). (c) Undemineralized, unstained, silver-impregnated section from the control tooth showing extensive, black silver deposits that almost completely obscured the hybrid layer. P, polyalkenoic acid copolymer. (d). The same type of section from the experimental tooth, showing sparsely distributed silver deposits (pointer) within the hybrid layer. Arrows: polyalkenoic acid copolymer within the dentinal tubules and resin composite. (e) Demineralized section from the control tooth that was stained with phosphotungstic acid and uranyl acetate. The hybrid layer was partially degenerated and missing, with empty regions occupied by epoxy resin (asterisk). These empty regions corresponded to the regions of extensive silver deposits depicted in Fig. 1c. (f) The same type of section from the experimental tooth, showing an intact normal hybrid layer.
