Clinical study on wedge-shape ditch restoration with several restorative materials]

There appeared difficulties in either cavity preparation of restoration retention when wedge-shaped ditch was restored.In order to choose an ideal material and method restored wedge-shaped ditch,we used three kinds of restorative materials (glass ionomer,light curing glass ionomer,light curing composite resin)and four restorative methods (glass ionomer,light curing glass ionomer,light curing composite resin,glass ionomer mixed with light curing composite resin).carried on clinical observation.According to the results of six months follow-up,four methods have no significant differences in abrasion,fracture,shedding and failing incidence(including of abrasion,fracture,and shedding) through statistical test(chi-square test).According to the results of one year follow-up,there were significant differences in abrasion and failing incidence,but fracture and shedding have no significant differences.Results showed that light curing composite resin was better than glass ionomer in wedge-shaped ditch restoration.     

固齿健周煎剂对老年小鼠的抗氧化作用

目的探讨中药固齿健周煎剂对老年小鼠的抗氧化作用。方法实验组为固齿健周煎剂灌胃的老年小鼠，对照组为灌胃等量自来水的青、老年小鼠。检测过氧化脂质、超氧化物歧化酶及过氧化氢酶。结果实验组与青、老年小鼠对照组比较差异均有显著性。结论固齿健周煎剂具有抗脂质过氧化的作用，可能对调节机体代谢功能、抗自由基损伤及恢复牙周组织健康有益     

热侧压充填法根尖封闭能力研究

本研究通过根尖渗漏试验和可见光分光光度法比较热侧压充填法和传统侧压充填法的根尖封闭能力。结果表明：加用封闭剂热侧压充填法的根尖封闭能力最佳，优于单纯热侧压充填法（Ｐ＜０．０５）及传统侧压充填法（Ｐ＜０．０１）。但由于国产牙胶尖易粘至热充填器上带出，操作不便，目前推广应用热侧压法尚有困难。     

HSV-TK自杀基因对涎腺多形性腺瘤细胞治疗的实验研究

目的研究单纯疱疹病毒胸苷激酶基因(Herpes simplex virus thymidine kinase，HSV-TK)／丙氧鸟苷(ganciclovir，GCV)系统对人涎腺多形性腺瘤体外基因治疗的作用。方法采用腺病毒包装重组脂质体介导的含有HSV-TK全长的cDNA真核表达质粒PDC312-HSVTK转染人涎腺多形性腺瘤细胞，通过RT-PCR检测TK基因在转染细胞中的表达；用MTT法检测HSV-TK／GCV系统对多形性腺瘤细胞的杀伤作用和旁观者效应：采用倒置显微镜、组织学染色等观察HSV-TK／GCV系统作用细胞后的形态学改变。结果HSV-TK基因转染24小时后，肿瘤细胞开始出现空泡性变；转染48小时后，RT-PCR从转染的细胞中成功扩增出1150bp的特异性TK基因片段。转染36小时后加入不同浓度的GCV治疗，细胞出现核固缩，胞浆裂解，随之细胞死亡、脱壁的现象。细胞存活率随HSV-TK／GCV作用时间延长而逐渐下降，当加入10^-4mol／LGCV治疗7天时，HSV-TK／GCV系统的杀伤作用最强，细胞存活率为10．3％。当TK阳性的细胞占细胞总数50％时，其旁观者效应最明显，细胞存活率为31．7％。结论HSV-TK／GCV系统对涎腺多形性腺瘤细胞具有明显的杀伤作用和旁观者效应。     

Clinical evaluation of the anti-plaque effect of a commercial chewing gum

OBJECTIVE: The objective of this research was to evaluate the dental plaque control effect of a chewing gum versus brushing with a dentifrice via four clinical studies. METHODOLOGY: Study 1 compared a commercial chewing gum (Colgate Dental Gum, CDG) with a water control after 24 hours post-brushing; Studies 2 and 3 compared CDG to two different brands of commercially available fluoride dentifrices after 24 hours post-brushing; Study 4 examined the anti-plaque effect of CDG plus a regular fluoride dentifrice (Colgate Winterfresh Gel, CWG) versus brushing with CWG alone for five days. The 24-hour clinical tests employed the Modified Gingival Margin Plaque Index (MGMPI), while the Quigley-Hein Plaque Index (QHPI) was used for the five-day study. All studies utilized a randomized, crossover design with a one-week washout period, and were single-blinded to the clinical evaluator. RESULTS: In Study 1, the mean MGMPI score for CDG was significantly lower (p < 0.05) compared to the water control. In Studies 2 and 3, while brushing with regular fluoride dentifrices provided improved plaque control compared to CDG, the chewing gum alone with no tooth brushing delivered a plaque reduction 60% as effective as brushing with a fluoride dentifrice. In Study 4, the group using the combination of chewing with CDG and brushing with CWG provided a significantly lower (p < 0.05) mean QHPI score compared to the group using the dentifrice only, particularly on the hard-to-brush lingual surfaces. CONCLUSIONS: Four clinical studies demonstrated that CDG provides a plaque control benefit. The results suggest that chewing gum may serve as an effective oral hygiene device when brushing may not be possible and, additionally, that chewing gum may serve as an effective adjunct to brushing for enhanced oral health.     

Chondroma of the cheek: A case report

An extremely rare case of soft tissue chondroma occurring in the right cheek of a 47-year-old woman is reported. The localized nodular tumor was encapsulated and composed of hyalinized cartilage with fine calcifications. Most tumor cells were positive for vimentin and S-100 protein, but negative for cytokeratin, factor VIII, and smooth muscle actin. It seems likely that the tumor cells arise from uncommitted mesenchymal stem cells by metaplastic process.     

Effects of pH values of hydrogen peroxide bleaching agents on enamel surface properties

This study investigated the influence of pH values of bleaching agents on the properties of the enamel surface. Sixty freshly extracted premolars were embedded in epoxy resin and mesiodistally sectioned through the buccal aspect into two parts. The sectioned slabs were distributed among six groups (n=10) and treated using different solutions. Group HCl was treated with HCl solution (pH=3.0) and served as a positive control. Group DW, stored in distilled water (pH=7.0), served as a negative control. Four treatment groups were treated using 30% hydrogen peroxide solutions with different pH values: group HP3 (pH=3.0), group HP5 (pH=5.0), group HP7 (pH=7.0), and group HP8 (pH=8.0). The buccal slabs were subjected to spectrophotometric evaluations. Scanning electron microscopy investigation and Micro-Raman spectroscopy were used to evaluate enamel surface morphological and chemical composition alterations. pH value has a significant influence on the color changes after bleaching (p<0.001). Tukey's multiple comparisons revealed that the order of color changes was HP8, HP7>HP5, HP3>HCl>DW. No obvious morphological alterations were detected on the enamel surface in groups DW, HP7, and HP8. The enamel surface of groups HCl and HP3 showed significant alterations with an erosion appearance. No obvious chemical composition changes were detected with respect to Micro-Raman analysis. Within the limitations of this study, it was concluded that no obvious morphological or chemical composition alterations of enamel surface were detected in the neutral or alkaline bleaching solutions. Bleaching solutions with lower pH values could result in more significant erosion of enamel, which represented a slight whitening effect.     

变形链球菌在父子间传播的研究

目的　本实验应用随机引物聚合酶链反应法 (AP PCR)对父子间变链的传播进行研究 ,以期为龋病预防提供新思路和理论依据。方法　随机选取中国沈阳一个幼儿园 10名 3～ 5岁的儿童及其父亲作为研究对象 ,取父亲非刺激性全唾液并刮取儿童牙菌斑 ,进行细菌培养 ,用酚 -氯仿法抽提细菌DNA ,进行PCR反应 ,电泳。结果　儿童共分离出 16个基因型 ,3个与父亲的一致 ,占 18.8%。结论　在中国家庭父子间存在变链传播