Decellularized human amniotic membrane scaffolds: influence on the biological behavior of dental pulp stem cells.

OBJECTIVE: The objective of this study was to assess the characterization of human acellular amniotic membrane (HAAM) using various decellularization methods and their impact on the proliferation and differentiation of human dental pulp stem cells (DPSCs). The goal was to identify scaffold materials that are better suited for pulp regeneration. METHODS: Six different decellularization methods were used to generate the amniotic membranes. The characteristics of these scaffolds were examined through hematoxylin and eosin (H&E) staining, scanning electron microscopy (SEM), and immunohistofluorescence staining (IHF). The DPSCs were isolated, cultured, and their capacity for multidirectional differentiation was verified. The third generation (P3) DPSCs, were then combined with HAAM to form the decellularized amniotic scaffold-dental pulp stem cell complex (HAAM-DPSCs complex). Subsequently, the osteogenic capacity of the HAAM-DPSCs complex was evaluated using CCK8 assay, live-dead cell staining, alizarin red and alkaline phosphatase staining, and real-time quantitative PCR (RT-PCR). RESULTS: Out of the assessed decellularization methods, the freeze-thaw + DNase method and the use of ionic detergent (CHAPS) showed minimal changes in structure after decellularization, making it the most effective method. The HAAM-DPSCs complexes produced using this method demonstrated enhanced biological properties, as indicated by CCK8, alizarin red, alkaline phosphatase staining, and RT-PCR. CONCLUSION: The HAAM prepared using the freeze-thaw + DNase method and CHAPS methods exhibited improved surface characteristics and significantly enhanced the proliferation and differentiation capacity of DPSCs when applied to them. The findings, therefore demonstrate the capacity for enhanced pulp regeneration therapy.

Can apical periodontitis affect serum levels of CRP, IL-2, and IL-6 as well as induce pathological changes in remote organs?

OBJECTIVES: The aim of this study was to investigate whether apical periodontitis (AP) could cause systemic cytokine elevation and pathological changes in remote organs in an experimental animal model. MATERIALS AND METHODS: AP was induced in 36 Sprague Dawley (SD) rats. Serum levels of C-reactive protein (CRP), interleukin 2 (IL-2), and interleukin 6 (IL-6) were measured by enzyme-linked immunosorbent assays at different time intervals (0, 6, 12, 24, 48, and 96 h and 1, 2, 3, 4, 5, and 6 weeks) after pulp exposure. Multiple organs (the aortic arch, myocardium, liver, and spleen) were collected for histological observation. The results were analyzed by one-way analysis of variance (ANOVA). RESULTS: Serum levels of CRP, IL-2, and IL-6 were significantly elevated at all time points assessed after 6, 24, and 96 h, respectively. The peak values of serum cytokines (CRP 6.363 ± 0.05 ng/ml, IL-2 21.997 ± 0.15 ng/L, and IL-6 2.406 ± 0.02 ng/L) were reached at 1, 4, and 2 weeks, respectively, followed by a decline. Time-dependent reversible histopathological changes were detected in the aortic arch, myocardium, and spleen, whereas irreversible changes were found in the liver. CONCLUSIONS: AP elevated the levels of CRP, IL-2, and IL-6 in rat blood serum, causing reversible changes in the aortic arch, myocardium, and spleen as well as irreversible changes in the liver. CLINICAL RELEVANCE: AP may trigger a systemic immune response, impair remote organs, and affect the general health of patients.

Expression of Interleukin-1ß and Matrix Metalloproteinase-8 in Cytolytic and Noncytolytic Enterococcus faecalis-induced Persistent Apical Periodontitis: A Comparative Study in the Rat.

INTRODUCTION: Cytolytic Enterococcus faecalis possesses a highly toxic and proinflammatory capacity. Cytokines and proteases play important roles in the host inflammatory response. The aim of this study was to compare the local expression of interleukin (IL)-1ß and matrix metalloproteinase-8 (MMP-8) between persistent apical periodontitis (AP) infected by cytolytic and noncytolytic E. faecalis. METHODS: Eighty-four left upper first rat molars were divided into 4 groups: chronic AP group (n = 6), disinfection group (n = 6), cytolytic E. faecalis-infected persistent AP group (n = 36), and noncytolytic E. faecalis-infected persistent AP group (n = 36). Periradicular lesions were established after pulp exposure. After 3 weeks, root canals were prepared, and disinfected. E. faecalis strains ATCC 29212 or ATCC 700802 suspensions were inoculated into root canals 2 weeks later. Six samples were collected at different time points (1, 2, 3, 4, 5, and 6 weeks). The expression levels of IL-1ß and MMP-8 were detected by immunohistochemical staining. RESULTS: IL-1ß and MMP-8 expression trends in the cytolytic groups were similar to those of the noncytolytic group although at different time points the expression levels in the cytolytic group were significantly higher than those in the noncytolytic group (P < .01). IL-1ß expression enhancement occurred during the early phase of infection, whereas increased MMP-8 expression lasted for a prolonged period. CONCLUSIONS: Both E. faecalis strains could induce local IL-1ß and MMP-8 expression in persistent AP. Compared with noncytolytic E. faecalis, cytolytic E. faecalis may cause more severe local inflammation and tissue destruction in persistent AP.

[Preparation and properties of calcium silicate-phosphate composite bone cements].

In this paper, alpha-tricalcium phosphate (alpha-TCP) and tetracalcium phosphate (TTCP) respectively were chosen as basic compositions of phosphate bone cements. Other auxiliary materials such as hydroxyapatite (HAP), dicalcium phosphate dihydrate (DCPD), calcium carbonate (CaCO3), calcium oxide (CaO) and amorphous calcium silicate (CaSiO3) were added in the cements. Six kinds of composite bone cements were decided with 1.50 as their Ca/P ratio. Then the primary properties of them were studied. Ringer's simulated body fluid (SBF) tests were carried out for the samples. The changes of pH value in SBF and the compressive strength of the samples with the immersion time were studied. The results showed: the mixing liquid 0.25 M K2HPO4/KH2PO4 and amorphous CaSiO3 were effective for accelerating the setting of the cements; the initial setting time (It) was about 4-5.5 min and the final setting time (Ft) was about 18-19. 5 min. Amorphous calcium silicate can increase the compressive strength of the bone cements remarkably; the compressive strength of the alpha-TCP bone cement with the addition of suitable amount amorphous CaSiO3 reached 45.3 MPa after immersion in SBF for 14 days.

[Microstructure and adhesion of HAP-glass-alumina composite gradient bioceramics coating].

HAP-Glass-alpha-Al2O3 gradient coating on alumina ceramics substrate was prepared by multi-layer slurry-dipping and sintering process, effects of the composition of the coating on the microstructure and adhesion strength of the gradient coating were studied. R2O-Al2O3-B2O3-SiO2 system glass with low softening temperature and thermal expansion was used in the gradient coating. The composition of the coating was varied from interface to surface layer, i.e. the HAP concentration increased and glass concentration decreased gradually from the under layer to the surface layer. A suitable amount superfine alpha-Al2O3 was added in the gradient coating to reinforce the bonding strength between the coating and substrate. The results show that the use of R2O-Al2O3-B2O3-SiO2 system glass is propitious to sintering the coating at low temperature and to combination between the coating and substrate. The addition of superfine alpha-Al2O3 can reinforce the bonding strength between the coating and substrate, the highest bonding strength is about 48.2 MPa.

[Influences of R2O-Al2O3-B2O3-SiO2 system glass and superfine alpha-Al2O3 on the sintering and phase transition of hydroxyapatite ceramics].

The effects of R2O-Al2O3-B2O3-SiO2 system glass and superfine alpha-Al2O3 on the sintering and phase transition of hydroxyapatite (HAP) ceramics were assessed. The results showed that alpha-Al2O3 impeded the sintering of HAP and raised the sintering temperature. When glass and alpha-Al2O3 were used together to reinforce HAP ceramics, better results could be obtained; the bending strength of multiphase HAP ceramics approached 106 MPa when 10% (wt) alpha-Al2O3 and 20%(wt) glass were used and sintered at 1200 for 1 h.