Quality evaluation on Chinese clinical research literatures about dental caries in 1950-2005 / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The purpose of this study is to evaluate the quality level of Chinese clinical research about dental caries in 1950-2005.</p><p><b>METHODS</b>The Chinese clinical research literatures about dental caries in 1950-2005 were collected. All the literatures were evaluated by Jadad scale. The score of Jadad scale was form 0 to 5. Score 2 and below was poor quality literature, and score 3 and more was high quality literature. The full marks of Jadad scale was 5.</p><p><b>RESULTS</b>3,201 clinical research papers about dental caries were collected, in which 46 articles were high quality literature. In 3,201 papers, random allocation methods were mentioned in 142 papers, double-blind measure were performed in 26 papers, the withdrawn and missing cases were described in 256 papers.</p><p><b>CONCLUSION</b>The high quality literature of Chinese clinical research about dental caries in scientific research design is less. The scientific research design should be strength to enhance the total quality of Chinese clinical research about dental caries.</p>

Investigation of influence on apical sealability generated by root canal sealer placement / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the influence of sealer placement on apical sealability in root canal treatment.</p><p><b>METHODS</b>100 extracted single root canal teeth were selected. All canals were prepared by manual Protaper instrument in a step-back way. The samples were divided into 5 groups randomly. A group: 30 samples, sealer placement by chief gutta percha; B group: 30 samples, sealer placement by K file; C group: 30 samples, sealer placement by spreader; D group: 5 samples, a positive control; E group: 5 samples, a negative control. There were 2 subsets in each experimental group which were obturated by lateral gutta percha with or without sealer. Glucose oxidase method was used to measure the apical leakage at the 1st 2nd, 4th, 7th, 10th, 15th, 20th, 25th, 30th day of the experiment.</p><p><b>RESULTS</b>Apical sealability varied with different sealer placement methods (F=4.832, P=0.001). Sealer placement by chief gutta percha (A group) had the best instant apical sealability. However, lateral gutta percha with or without sealer didn't affect the apical sealibility.</p><p><b>CONCLUSION</b>Placing the same kind sealer in different ways can affect the apical sealability. There were no significant differences of the apical leakage no matter the lateral gutta percha with or without sealer. In order to get better instant apical sealability and simplify the clinic operation, placing the sealer with a chief gutta percha while the lateral gutta percha without sealer is recommended.</p>

Effect of chemical compounds of Galla chinensis on enamel surface rehardening in vitro / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the effect of chemical compounds extracted from Galla chinensis on enamel surface rehardening in vitro.</p><p><b>METHODS</b>Sixty bovine enamel blocks with early carious lesions were randomly divided into six groups: group1 treated NaF (positive control); group2 with GCE; group3 with GCE-B; group4 with GCE-B1; group5 with GCE-B2 and group6 with deionized water (negative control). The lesions were subjected to a pH-cycling regime for 12 days. Surface enamel microhardness was measured on the enamel blocks before and after demineralization. After pH-cycling, and the percentage of surface microhardness recovery (SMHR) was calculated.</p><p><b>RESULTS</b>Obvious increase of the surface hardness of the enamel was observed in all the treatments except GCE-B2 and deionized water (P < 0.05).</p><p><b>CONCLUSIONS</b>The present study demonstrates the potential of the three GCEs (GCE, GCE-B and GCE-B1) to effect net rehardening of artificial carious lesions under dynamic pH-cyclic conditions.</p>

Effects of cecropin-XJ on growth and adherence of oral cariogenic bacteria in vitro / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Cecropin-XJ belongs to cecropin-B, which is the most potent antibacterial peptide found naturally. The aim of this study was to investigate the effects of cecropin-XJ on growth and adherence of oral cariogenic bacteria.</p><p><b>METHODS</b>Four oral cariogenic bacteria (Streptococcus mutans, Lactobacillus acidophilus, Actinomyces viscosus and Actinomyces naeslundii) were chosen for this experiment. The minimal inhibitory concentrations (MICs) and reductive percent of bacterial growth were used to assay the antibacterial activity of cecropin-XJ. Mammalian cytotoxicity of cecropin-XJ was tested with human periodontal membrane fibroblasts by tetrazolium (MTT) colorimetric assay. The bacterial morphological changes induced by cecropin-XJ were examined on scanning electron microscope (SEM). The influence of cecropin-XJ on bacterial adhesion to saliva-coated hydroxyapatite (S-HA) was measured by scintillation counting.</p><p><b>RESULTS</b>The MICs of cecropin-XJ for inhibition of the growth of four bacteria ranged from 4.0 to 42.8 micromol/L with the highest susceptible to A. naeslundii and the lowest susceptible to L. acidophilus. At pH 6.8, 5.5 and 8.2, 1/2 MIC of cecropin-XJ reduced the number of viable bacteria by 40.9%, 67.8% and 32.8% for S. mutans and by 28.1%, 57.2% and 37.9% for L. acidophilus. The activities against S. mutans and L. acidophilus increased at pH 5.5 compared with pH 6.8 (P < 0.01, respectively). In present of 50% saliva, 1/2 MIC of the peptide decreased the direct count of viable cells by 29.2% and 14.4% for S. mutans and L. acidophilus, respectively (P < 0.01 and P > 0.05, respectively), whereas almost no reduction counts were detected in the presence of 20% serum for both bacteria (P > 0.05, respectively). Mammalian cytotoxicity of cecropin-XJ from 1.0 to 100 micromol/L exhibited no cytotoxicity against human periodontal membrane fibroblasts (P > 0.05). Bacterial morphological changes induced by MIC of cecropin-XJ examined on SEM showed cell surface disruption. Furthermore, the ability of A. naeslundii adhesion to S-HA decreased significantly with MIC of cecropin-XJ for 10 and 20 minutes (P = 0.001 and 0.000, respectively), and S. mutans, A. viscosus to S-HA decreased significantly with MIC of cecropin-XJ for 20 minutes (P = 0.000, respectively).</p><p><b>CONCLUSIONS</b>Cecropin-XJ exhibited bactericidal action against cariogenic pathogens, and the antibacterial activity enhanced in the acid environment. The results also demonstrate that cecropin-XJ prevents S. mutans and actinomyces adsorption to S-HA. These findings suggest that Cecropin-XJ may have potential to prevent caries.</p>

Expression of matrixmetalloproteinase-8 on the bell-stage in human and rat tooth development / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To study the expression of MMP-8 in human and rat tooth development.</p><p><b>METHODS</b>Immunohistochemistry was used to detect the localization of MMP-8 protein while in situ hybridization was used to examine the expression of MMP-8 mRNA.</p><p><b>RESULTS</b>The expression of MMP-8 protein was localized in odontoblast and dentin matrix at the later bell stage in human tooth germ. The dentin was denser close to the pulp cavity. The expression of MMP-8 mRNA was found in very few polarized odontoblast at the early bell stage and all polarized odontoblast at the later bell stage in rat tooth germ.</p><p><b>CONCLUSION</b>The results suggested that MMP-8 involved in dentin matrix rebuilding in the process of dentin formation in human and rat dental development.</p>

An immunohistochemical study of the effects of excessive fluoride on type I collagen in rat developmental dentine / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To study the effects of excessive fluoride on type I collagen in rat developmental dentine.</p><p><b>METHODS</b>Eighty SD rats, 5 days old, were divided into experimental and control groups, 40 in each group. The experimental group received subcutaneous injection of 0.2% NaF every 4 days (the dose was 2 mg NaF per kg body wt). The same volume of 0.9% NaCl was used in the control. Twenty rats in each group were killed 4 days after the second and the seventh injection respectively. The expression of type I collagen was assayed with immunohistochemical technique.</p><p><b>RESULTS</b>4 out of 20 rats after two injections showed abnormal distribution of type I collagen (dense stain of collagen in the odontoblast, aggregation of collagen in the dentine and disordered arrangement of collagen in the predentine; All 20 rats after seven injections showed abnormal distribution of type I collagen.</p><p><b>CONCLUSION</b>Excessive fluoride may affect the metabolism of type I collagen in rat developmental dentine.</p>