Considerations of the classification and treatment for fused teeth / 中华口腔医学杂志

Fused teeth were a phenomena of teeth anomalies in shape, which can affect the dental teeth both in primary and permanent dentition. Fused teeth do not only cause problems on crowding of dentition, abnormal occlusion and aesthetic, but also increase risks of dental caries, endodontics diseases, periapical diseases and periodontal diseases. Fusion of deciduous teeth may lead to abnormality of subsequent permanent teeth. Treatment of fused teeth may require multidisciplinary approach in endodontics, periodontics, oral and maxillofacial surgery, prosthodontics and orthodontics. The aim of the present article is to review the etiology, classification, clinical manifestations and treatment of fused teeth in order to provide dental clinicians with a reference of clinical management for fused teeth.

Etiology and pathogenesis of internal root resorption / 中华口腔医学杂志

Internal root resorption is a pathologic phenomenon with a characterization of the intraradicular dentin destruction due to the abnormal activities of odontoclasts. With its insidious pathology, internal root resorption can progress to a great extent before its clinical detection. The etiology and natural history of internal root resorption are uncertain and the associated key molecular pathogenesis have not been understood completely. The resorption is usually initiated by a stimulus with the loss of the protective predentin and progressed by the continuous stimuli of pulp infection. Various factors including trauma, chronic inflammation of the pulp, pulpotomy and tooth transplantation have been proposed for the occurrence of internal root resorption. The present paper reviews the etiology and pathogenesis of internal root resorption and provides guidance for the early intervention in the clinical practice.

Effect of CD-14 and toll like receptors on the expression of interleukin-6 induced by lipopolysaccharides of Porphyromonas endodontalis / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the effect of cluster of differentiation 14 (CD-14) and Toll like receptors (TLR) on the expression of interleukin-6 (IL-6) mRNA induced by Porphyromonas endodontalis (Pe) lipopolysaccharides (LPS).</p><p><b>METHODS</b>MC3T3-E1 cells were treated with 10 mg/L Pe-LPS for different hours, and the cells uninvolved by anything as the blank group. The expression of IL-6 was detected by reverse transcription polymerse chain reaction (RT-PCR) and enzyme-liked immunosorbent assay (ELISA). The expression of CD-14, TLR-2 and TLR-4 mRNA was observed at different time point (0 - 24 h) by RT-PCR. The protein of CD-14, TLR-2 and TLR-4 was analyzed with a flow cytometer. MC3T3-E1 cells were pretreated with anti-CD-14, anti-TLR-2 and anti-TLR-4 antibody for 1 h, and then cells were stimulated with 10 mg/L Pe-LPS for 6 h. The expression of IL-6 mRNA was examined by RT-PCR. Statistical analysis was performed using one-way ANOVA Dunnett-t test with SPSS 11.0 software package.</p><p><b>RESULTS</b>The IL-6 mRNA and proteins increased significantly after treatment with Pe-LPS. When MC3T3-E1 cells treated by Pe-LPS for 6 h, the expression of proteins soared from (11.696 ± 0.672) ng/L to (36.534 ± 0.574) ng/L (P < 0.01); In the control group, the CD-14 and TLR-4 mRNA are ambly-expression, and the ratios of CD-14 and TLR-4 positive cells were (39.038 ± 3.131)% and (11.438 ± 0.385)% respectively in MC3T3-E1. After treatment by Pe-LPS, the expression of CD-14 and TLR-4 mRNA increased significantly, and the ratios of CD-14 and TLR-4 positive cells markedly increased to (62.407 ± 1.800)% and (21.367 ± 2.271)%. TLR-2 expression did not change apparently after Pe-LPS treatment. The expression of IL-6 mRNA was partly inhibited by anti-CD-14 or anti-TLR-4 antibody, but not by TLR-2.</p><p><b>CONCLUSIONS</b>Pe-LPS can induce the expression of IL-6 in osteoblast MC3T3-E1 through CD-14 and TLR-4, but not TLR-2.</p>

Inhibitory effects of Porphyromonas endodontalis lipopolysaccharides on proliferation and differentiation of mouse osteoblast / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To observe the effect of lipopolysaccharides (LPS) extracted from Porphyromonas endodontalis (Pe) on osteoblast cell proliferation and the activity of alkaline phosphatase (ALP) and interleukin (IL)-6 secretion and to investigate the role of Pe-LPS in osteoblast proliferation and differentiation.</p><p><b>METHODS</b>MC3T3-E1 cells were treated with different concentrations of Pe-LPS (10, 25, 50 mg/L) respectively. The relative growth rate (RGR) was detected by methyl thiazolyl tetrazolium (MTT) at different time point (12, 24, 48, 72 h). MC3T3-E1 cells were also stimulated with 10, 25 or 50 mg/L Pe-LPS for 6, 12, 24 and 48 h. The activity of ALP was detected by enzyme kinetics assay and the secretion of IL-6 was detected by enzyme-linked immunosorbent assay (ELISA).</p><p><b>RESULTS</b>After the stimulation with 25 or 50 mg/L Pe-LPS for 72 h, the RGR of MC3T3-E1 cells descend to 87.46% and 71.12%. The ALP activities of MC3T3-E1 cells were inhibited obviously (P < 0.05) after the stimulation of different concentrations (10, 25, 50 mg/L) Pe-LPS for more than 24 hours. ELISA result showed that IL-6 increased to 32.21 ng/L treated with the 25 mg/L Pe-LPS for 6 h, 25 mg/L Pe-LPS gradually increased the expression of IL-6 from the ELISA results.</p><p><b>CONCLUSIONS</b>Pe-LPS can induce the secretion of IL-6 in MC3T3-E1 and decrease the ALP activities of MC3T3-E1, the differentiation of osteoblasts was inhibited. with the long-time toxicity action of Pe-LPS, the proliferation rate of MC3T3-E1 also markedly decreased.</p>

Study of signal transduction pathway in the expression of inflammatory factors stimulated by lipopolysaccharides from Porphyromonas endodontalis in osteoblasts / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To quantify the interleukin (IL)-1beta mRNA and IL-6 mRNA expression induced by lipopolysaccharides ([PS) extracted from Porphyromonoas endodontalis (P. endodontalis) in osteoblasts, and to relate P. endodontalis LPS to the bone resorptive pathogenesis in the lesions of chronic apical periodontitis.</p><p><b>METHODS</b>MG63 cells was pretreated with PD98059 or SB203580 for 1 h and then treated with P. endodontolis LPS for 6 h. The expression of IL-1beta mRNA and IL-6 mRNA were detected by reverse transcription polymerase chain reaction (RT-PCR) technique.</p><p><b>RESULTS</b>The production of IL-1beta mRNA induced by P. endodontalis LPS decreased in osteoblasts pretreated with PD98059. Both of the production of IL-1beta mRNA and JL-6 mRNA induced by P. endodontalis LPS decreased in osteoblasts pretreated with SB203580.</p><p><b>CONCLUSION</b>The synthesis of IL-1beta mRNA stimulated by Pendodontalis LPS in MG63 probably occur via extracellular signal-regulated kinase (ERK) 1/2 and p38 mitogen activated protein kinase (MAPK) signal transduction system. The synthesis of IL-6 mRNA stimulated by P.endodontalis LPS in MG63 probahly occur via p38MAPK signal transduction system.</p>

Effects of Nd:YAG laser on micro-tensile bond strength of single bond adhesive system for non-carious sclerotic dentin / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of Nd:YAG laser on microtensile bond strength of single bond adhesive system for non-carious sclerotic dentin.</p><p><b>METHODS</b>Ten human molars with occlusal wearing were cut into equal halves (nearly 12 mm(2)), and randomly divided into experimental group and control group. The teeth in experimental group were processed with Nd:YAG laser (1 W, 10 Hz), and then applied with Scotchbond and filled with Z350 resin. In control group, the teeth were processed with single bond and filled with Z350 resin. The specimens were sectioned, and the microtensile bond strengths of each sample was tested by a universal testing machine.</p><p><b>RESULTS</b>The bond strength of the experimental group [(26.11 ± 1.62) MPa] was significantly higher than that of the control group [(22.27 ± 2.16) MPa], P < 0.05. Stero-microscope examination indicated that most of the fractures occurred in dentin-resin interface.</p><p><b>CONCLUSIONS</b>Nd:YAG laser can increase the microtensile bond strength of single bond adhesive system in non-carious sclerotic dentin.</p>

Effect of static magnetic field on bone morphogenetic protein-2 in periodontal membrane of experimental periodontitis rat / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the effect of static magnetic field on expression of bone morphogenetic protein-2(BMP-2) in the periodontal membrane of experimental periodontitis rat.</p><p><b>METHODS</b>Experimental periodontitis of rat was formed by ligaturing the neck of rat teeth and feeding sugar of high concentration. The magnet which the intensity of magnetic field was 0.12 tesla was put into their cheeks. The rats were sacrificed at 2nd day, 4th day and 7th day, respectively. Immuno-histochemical techniques were used to evaluate the change of BMP-2 expression.</p><p><b>RESULTS</b>BMP-2 was mainly found in the plasma of fibroblast, osteoblast, cementocyte and odontoblast separately. There was not clearly difference between the periodontitis group and the normal group, but BMP-2 in the experimental group treated with static magnetic field was higher than the two groups.</p><p><b>CONCLUSION</b>Static magnetic field plays an important role in repairing and remodeling of periodontitis.</p>