Biomedical subjects

Ming-Shu Lee

Publications and source records attributed to Ming-Shu Lee.

4 recordsLinked to original sources

PubMed2007

Effects on microstrain and conversion of flowable resin composite using different curing modes and units.

The flowable resin composite, Tetric Flow, was used to measure microstrain and degree of conversion after hardening with each of three curing machines: XL3000(XL) for 10, 20, 30, and 40 s; Optilux 501 using conventional mode (OC) for 10, 20, 30, and 40 s, as well as Optilux boost (OB, 10 s) and ramp modes (OR, 20 s); and LEDemetron (LEDe) for 10, 20, 30, and 40 s. The emitted power density and spectral distribution of the three light curing units were also measured. The LEDe output energy spectrum was centralized between 425 and 490 nm, which encompasses the excited wavelength of camphorquinone. The microstrain produced by the curing process is as a second-degree polynomial for each light source. The OB microstrain was highest, while the OR microstrain was lower. The ranking in order of degree of monomer conversion was as follows: XL10 <or=<or= OC10 <or=<or= LED 10 = OR = XL 20 = OC 20 = XL 30 <or=<or= LED 20 <or=<or= OC30 = LED 40 = XL 40 = OC40 = LED 30 <or= OB. The degree of conversion cured with OB was significant higher than other curing modes except OC30, OC40, LEDe30, LEDe40, and XL40. The conversion value of XL10 was the lowest. The LEDe produced higher conversion for the same emitted energy compared to the two halogen units.

Composite Resins↗

PubMed2004

Intrusion and reversal of a free-standing natural tooth bounded by two implant-supported prostheses: a clinical report.

Although intrusion of natural tooth abutments in tooth-implant connected fixed prostheses has been reported, it can also occur to a free-standing natural tooth bounded by implant prostheses. For the patient described in this article, intrusion was noted with a natural tooth bounded by 2 implant-supported prostheses 5 months after insertion of the prostheses. The intrusion was reversed completely after 5 months with appropriate management. The course of treatment and possible mechanisms of intrusion are provided.

Bicuspid↗

PubMed2004

The role of lipopolysaccharide in infectious bone resorption of periapical lesion.

BACKGROUND: The role of lipopolysaccharide (LPS) in periapical lesion-induced bone resorption was investigated. Polymyxin B (PMB), a specific inhibitor of LPS, was evaluated to treat the apical lesion. METHODS: Lipopolysaccharide isolated from two common endodontic pathogens, Fusobacterium nucleatum and Porphyromonas endodontalis, stimulated mouse macrophage (J774) to release interleukin-1alpha (IL-1 alpha) and tumor necrosis factor-alpha (TNF-alpha) in a time-dependent manner. RESULTS: Combination of LPS further enhanced the stimulation. PMB inhibited these effects significantly. LPS also stimulated matrix metalloproteinase-1 (MMP-1) gene expression in J774, whereas anti-IL-1 alpha and anti-TNF-alpha antibodies, as well as PMB, diminished this effect. A disease model of periapical lesion was established in Wistar rat. Administration of PMB reduced the extent of lesion-associated bone resorption by 76% to approximately 80%, and simultaneously reduced the numbers of MMP-1-producing macrophages. CONCLUSIONS: It is suggested that LPS released from the infected root canal triggers the synthesis of IL-1 alpha and TNF-alpha from macrophages. These pro-inflammatory cytokines up-regulate the production of MMP-1 by macrophages to promote periapical bone resorption.

Alveolar Bone Loss↗

PubMed2003

Nitric oxide promotes infectious bone resorption by enhancing cytokine-stimulated interstitial collagenase synthesis in osteoblasts.

This experiment was undertaken to determine the role of macrophage-derived nitric oxide (NO) in mediating lipopolysaccharide (LPS)-induced bone resorption by using an in vitro co-culture system and an in vivo model of infectious bone resorption. Our results demonstrated that LPS stimulated the expression of inducible nitric oxide synthase (iNOS) and tumor necrosis factor (TNF)-a mRNAs and nitrite synthesis in the J774 mouse macrophage cell line but not in the UMR-106 (rat) and MC3T3-E1 (mouse) osteoblast cell lines. Conditioned media (CM) from LPS-stimulated J774 triggered only low to moderate levels of iNOS mRNAs in MC3T3-E1 and a trivial effect in UMR-106. On the other hand, CM induced matrix metalloproteinase-1 (MMP-1) gene expression in both osteoblast cell lines. The NOS inhibitor N(G)-monomethyl-L-arginine (L-NMMA) did not alter this effect in MC3T3-E1 and UMR-106, whereas TNF-a antibody diminished the CM-induced MMP-1 gene expression in both cell lines. Interestingly, SNAP, a NO donor, although by itself is not a MMP-1 stimulator for UMR-106, augmented the TNF-alpha-stimulated MMP-1 mRNA production in UMR-106. In a J774/UMR-106 co-culture system, LPS stimulated significant MMP-1 gene expression in UMR-106, and this upregulation was abolished by L-NMMA and TNF-alpha antibodies. Immunohistochemical analysis in a rat model of infectious bone resorption (periapical lesion) showed co-distributions of iNOS+ macrophages and MMP-1+ osteoblasts around the osteolytic areas. Administration of L-NMMA markedly reduced the extent of bone loss and the percentage of MMP-1-synthesizing osteoblasts. These data suggest that NO derived from macrophages after LPS stimulation may enhance bone loss by augmenting the cytokine-induced MMP-1 production in osteoblasts.

3T3 Cells↗