Table 1.
Composition of Simulated Body Fluid (SBF).
Fig 1.
Infrared spectra (2,000–500 cm-1) of PAMAM coated dentin discs.
(a) Sound dentin (black line). (b) Dentin disc coated with pure G3.0 PAMAM dendrimers for 30s (red line). (c) Dentin disc immersed in pH 5.8 PBS for 2h after it was coated with G3.0 PAMAM dendrimers (blue line). (d) Untreated dentin disc immersed in pH5.8 PBS for 2h (green line).
Fig 2.
Infrared spectra (2,000–500 cm-1) of EDTA demineralized dentin discs crosslinked with PAMAM dendrimers.
(a) Sound dentin (black line). (b) Dentin disc demineralized with 0.5 M neutral EDTA solution at room temperature for 72h (red line). (c) Demineralized dentin disc crosslinked with G3.0 PAMAM dendrimers using 0.25% glutaraldehyde at 4°C for 24h (green line). (d) PAMAM dendrimers crosslinked demineralized dentin disc immersed in pH 5.8 PBS for 2h (blue line). (e) Demineralized dentin disc immersed in pH 5.8 PBS for 2h without PAMAM dendrimer crosslinking (pink line).
Fig 3.
SEM images of dentin surface and longitudinal section morphology indicating dentinal tubules occlusion.
(A, B) Dentin discs etched with 10% citric acid for 30s. All of the dentinal tubules were open. (C, D) Dentinal tubules occluded with newly formed rod-like crystals after dentin discs were coated with PAMAM dendrimers and immersed in SBF for 1w. The outermost part of tubules was left patent. (E, F) Dentinal tubules occluded with newly formed precipitates projecting form dentin surface. Part of the dentin surface was covered with globular and rod-like crystals. (G) Dentinal tubules occluded from the dentin surface to a depth up to approximately 20μm. (H) In control group, no significant difference was observed before and after dentin discs were directly immersed in SBF for 1w, without treated with PAMAM dendrimer.
Fig 4.
SEM images of the remineralization of demineralized dentin discs.
(A, B) Dentin discs demineralized with neutral EDTA solution for 72h. (C, D) EDTA demineralized dentin discs crosslinked with G3.0 PAMAM dendrimers using 0.25% glutaraldehyde for 24h, exhibiting a “corn-on-the-cob” appearance. (E, F) Flake-like crystals were induced on the surface and covered the wall of dentinal tubules after PAMAM crosslinked dentin discs were treated with SBF for 1w, with dentinal tubules still left patent. (Insert of (E)) EDS showed the Ca/P molar ratio of the mineral crystals was 1.59±0.05. (G, H) No significant mineral crystals formed on the demineralized dentin discs after they were immersed in SBF for 1w, without treated with PAMAM dendrimers.
Fig 5.
XRD spectra of EDTA demineralized dentin discs crosslinked with PAMAM dendrimers.
(a) Neutral EDTA demineralized dentin (black line). (b) PAMAM dendrimers crosslinked demineralized dentin mineralized in SBF for 1w (red line). (c) Sound dentin (blue line).
Fig 6.
Mechanism of glutaraldehyde crosslinking.
(A) Chemical reaction equation. (B) Schema chart that reveals the process of PAMAM dendrimers crosslinked to demineralized dentinal collagen by using glutaraldehyde.