Expression of Matrix Metalloproteinases and Tissue Inhibitor of Matrix Metalloproteinases during Apical Periodontitis Development.

INTRODUCTION: Matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) are considered important mediators of the periapical immune response to infection. This study aimed to clarify the putative relationship between MMPs and TIMPs by elucidating the activity of MMP-1, MMP-2, MMP-8, MMP-9, TIMP-1, and TIMP-2 in the temporal development of apical periodontitis (AP) in mice. METHODS: AP was induced in the lower first molars of 30 male Kunming mice. The animals were randomly killed at 0, 7, 14, 28, 60, and 90 days after pulp exposure. The jaws were removed and subjected to quantitative real-time reverse transcription polymerase chain reaction, enzyme-linked immunosorbent assay, and immunohistochemical analysis. RESULTS: The MMP-1, MMP-2, MMP-8, MMP-9, TIMP-1, and TIMP-2 messenger RNA and protein expression levels increased with periapical inflammation progression (P < .05). The MMP-1, MMP-2, MMP-9, TIMP-1, and TIMP-2 messenger RNA and protein expression levels increased during the acute and chronic stages of periapical lesions, with less MMP-2 and MMP-9 expression levels at the chronic stage (P < .05). The MMP-8 expression increased at the chronic stage of inflammation (P < .05) but not at the acute stage. Immunostained MMP-2 and TIMP-1 were observed in all experimental periods. CONCLUSIONS: MMP-1, MMP-2, MMP-8, MMP-9, TIMP-1, and TIMP-2 were expressed in all periapical samples with varying levels between them. MMP expression could be related to TIMP expression in the temporal development of AP.

[Dens in dente: report of 3 cases and review of the literature].

PURPOSE: To explore the diagnosis and clinical treatment of dens in dente. METHODS: Preventive resin restoration, root canal treatment, apical barrier technique and apexification were used to treat three cases of dens in dente, respectively. The curative effects were assessed by general examinations and imageological examinations during postoperative follow-up visits. RESULTS: Three patients with different type and degree of dens in dente achieved good therapeutic effect and favorable prognosis through different treatment methods. CONCLUSIONS: Dens in dente is complex clinically and the treatment is difficult. Clinicians should improve the understanding of dens in dente. The keys to successful treatment are early diagnosis and early treatment. In addition, it is important to take proper measures according to the type and degree of dens in dente, to preserve the diseased tooth as much as possible.

Photoluminescence properties of a new orange-red-emitting Sm(3+)-La3SbO7 phosphor.

The antimonate compound La3SbO7 has high chemical stability, lattice stiffness and thermal stability. Orange-red-emitting antimonate-based phosphors La3SbO7:xSm(3+) (x = 0.02, 0.05, 0.08, 0.10, 0.15, 0.20 and 0.25) were synthesized. The phase structure and photoluminescence properties of these phosphors were investigated. The emission spectrum obtained on excitation at 407 nm contained exclusively the characteristic emissions of Sm(3+) at 568, 608, 654 and 716 nm, which correspond to the transitions from (4)G5/2 to (6)H5/2, (6)H7/2, (6)H9/2 and (6)H11/2 of Sm(3+), respectively. The strongest emission was located at 608 nm due to the (4)G5/2→(6)H7/2 transition of Sm(3+), generating bright orange-red light. The critical quenching concentration of Sm(3+) in La3SbO7:Sm(3+) phosphor was determined as 10% and the energy transfer between Sm(3+) was found to be through an exchange interaction. The International Commission on Illumination chromaticity coordinates of the La3SbO7:0.10Sm(3+) phosphors are located in the orange-red region. The La3SbO7:Sm(3+) phosphors may be potentially used as red phosphors for white light-emitting diodes.

Autophagy in SDF-1α-mediated DPSC migration and pulp regeneration.

Critical morphological requirements for pulp regeneration are tissues replete with vascularisation, neuron formation, and dentin deposition. Autophagy was recently shown to be related to angiogenesis, neural differentiation, and osteogenesis. The present study aimed to investigate the involvement of autophagy in stromal cell-derived factor-1α (SDF-1α)-mediated dental pulp stem cell (DPSC) migration and pulp regeneration, and identify its presence during pulp revascularisation of pulpectomised dog teeth with complete apical closure. In vitro studies showed that SDF-1α enhanced DPSCs migration and optimised focal adhesion formation and stress fibre assembly, which were accompanied by autophagy. Moreover, autophagy inhibitors significantly suppressed, whereas autophagy activator substantially augmented SDF-1α-stimulated DPSCs migration. Furthermore, after ectopic transplantation of tooth fragment/silk fibroin scaffold with DPSCs into nude mice, pulp-like tissues with vascularity, well-organised fibrous matrix formation, and new dentin deposition along the dentinal wall were generated in SDF-1α-loaded samples accompanied by autophagy. More importantly, in a pulp revascularisation model in situ, SDF-1α-loaded silk fibroin scaffolds improved the de novo ingrowth of pulp-like tissues in pulpectomised mature dog teeth, which correlated with the punctuated LC3 and Atg5 expressions, indicating autophagy. Our findings provide novel insights into the pulp regeneration mechanism, and SDF-1α shows promise for future clinical application in pulp revascularisation.