The effect of simvastatin on remodelling of the alveolar bone following tooth extraction

Suppression of residual ridge resorption after tooth extraction is a hot spot in dental research. Recently, simvastatin was reported to influence bone turnover by stimulating bone formation. In this study, the effect of simvastatin application on residual ridge resorption following tooth extraction was investigated. Sixty male Wistar rats were randomly divided into experimental and control groups (n=30). Polylactic acid/polyglycolic acid copolymer carriers, with or without simvastatin, were implanted into extraction sockets of right mandibular incisors. The rats were killed at 1, 2, 4, 8 or 12 weeks after implantation. The relative height of the residual alveolar ridge was significantly greater in the experimental compared to the control group at 2, 4, 8 and 12 weeks. The bone mineral density in the experimental group was significantly higher than that in the control group at 4, 8 and 12 weeks. A larger newly formed bone island was observed in the experimental group at 4 weeks, and higher bone formation rate and quality were found than in the control group at different time points except 1 week. The findings indicate that local application of simvastatin would effectively preserve the residual alveolar bone by promoting bone formation in the extraction socket.     

翼外肌上头与颞下颌关节盘关系的研究

目的探讨翼外肌上头与关节盘的关系。方法对４７侧老年尸体颞下颌关节标本进行了斜矢状面上的解剖学和组织学研究。结果①显微镜下观察翼外肌上头纤维可附着于关节盘、关节囊、关节盘前附着及髁突；②翼外肌上头附着于髁突的纤维平均为５２％，附着于关节盘的纤维为１０％，附着于关节囊的纤维为２４％，附着于下颌前附着的纤维量为４％；③翼外肌上头附着于关节盘的比例与关节盘前移无确切相关性；④翼外肌上头纤维与关节盘纤维的连接方式包括结点连接、肌腱连接和端端连接。结论翼外肌上头主要附着于髁突，附着于关节盘的少量纤维不足以独立地使关节盘发生前移位。     

口腔扁平苔藓浸润细胞免疫组化分析

为探讨免疫应答在扁平苔藓发病过程中的作用及相互关系，本研究中应用ABC技术，用T3、T4、T8、IgG单抗及S－100蛋白标记病损已浸润细胞。结果表明：病损区以细胞免疫为主，淋巴细胞数量与上皮钉突的增殖程度呈正相关；病损区中郎罕氏细胞明显偏高；基底膜区损害与T细胞数量呈正相关；IgG阳性细胞散在分布于病损区，其阳性物质在基底膜区沉积。提示该疾病以细胞免疫为主，同时有体液免疫应答的参与。     

熔附条件对牙科复合树脂中SP1 SiO_2表面结构及形态的影响

目的:研究熔附温度和熔附时间对多微孔纳米二氧化硅粒子(SP1 SiO2)表面结构及形态的影响。方法:将SP1SiO2以250℃/h的升温速度分别升至500、650、800、950、1100℃,并分别保持10、30min和3h制作试样,进行表面结构及形态测试。结果:随烧结温度的增高和时间的延长,SP1 SiO2颗粒表面的Si-OH键特征峰值逐渐减弱,条件为950℃、10min和30min,650℃、3h时完全消失;随着熔附温度的升高和熔附时间的延长颗粒增大、粒度分布变窄。结论:熔附温度和熔附时间影响SP1 SiO2颗粒表面的Si-OH含量和颗粒大小、粒度分布。     

Miniature specimens for fracture toughness evaluation of dental resin composites

Objective

Millimeter-scale (“miniature”) specimens enable in-situ evaluation of mechanical properties of engineering materials at reduced cost. Here three such specimens for measuring fracture toughness (K_C) are developed and implemented to new dental materials. The latter include concurrent methacrylate-based and new ether-based resin composites designed to reduce polymerization stress and enhance service life in restored teeth.

A comparison of enamelin and amelogenin expression in developing mouse molars

Amelogenin and enamelin are structural proteins in the enamel matrix of developing teeth. The temporal and spatial patterns of enamelin expression in developing mouse molars have not been characterized, while controversy remains with respect to amelogenin expression by odontoblasts and cementoblasts. Here we report the results of in situ hybridization analyses of amelogenin and enamelin expression in mouse molars from postnatal days 1, 2, 3, 7, 9, 14, and 21. Amelogenin and enamelin mRNA in maxillary first molars was first observed in pre-ameloblasts on the cusp slopes at day 2. The onsets of amelogenin and enamelin expression were approximately synchronous with the initial accumulation of predentin matrix. Both proteins were expressed by ameloblasts throughout the secretory, transition, and early maturation stages. Enamelin expression terminated in maturation stage ameloblasts on day 9, while amelogenin expression is still detected in maturation stage ameloblasts on day 14. No amelogenin expression was observed in day 21 mouse molars. Amelogenin and enamelin RNA messages were restricted to ameloblasts. No expression was observed in pulp, bone, or along the developing root. We conclude that amelogenin and enamelin are enamel-specific and do not directly participate in the formation of dentin or cementum in developing mouse molars.     

Diversity,novelty, antimicrobial activity,and new antibiotics of cultivable endophytic actinobacteria isolated from psammophytes collected from Taklamakan Desert

Three hundred and twenty endophytic actinobacterial strains were isolated from psammophytes collected from Taklamakan Desert and identified. Among them, three strains already had been identified as new species of two genera and sixteen isolates showed relatively low 16S rRNA similarities < 98.6% to validly described species. Seventy-five of the isolates were selected as representative strains to screen antibacterial activity and mechanism. Forty-seven strains showed antagonistic activity against at least one of the indicator bacteria. Two Streptomyces strains produced bioactive compounds inducing DNA damage, and two Streptomyces strains produced bioactive compounds with inhibitory activity on protein biosynthesis. Notably, the strain Streptomyces sp. 8P21H-1 that demonstrated both strong antibacterial activity and inhibitory activity on protein biosynthesis was prioritized for exploring new antibiotics. Under the strategy of integrating genetics-based discovery program and MS/MS-based molecular networking, two new streptogramin-type antibiotics, i.e., acetyl-griseoviridin and desulphurizing griseoviridin, along with known griseoviridin, were isolated from the culture broth of strain 8P21H-1. Their chemical structures were determined by HR-MS, and 1D and 2D NMR. Desulphurizing griseoviridin and griseoviridin exhibited antibacterial activities by inhibiting translation.     

Infectious keratitis after transepithelial photorefractive keratectomy: A case report

Transepithelial photorefractive keratectomy (tPRK) promotes faster re-epithelialization which in turn can reduce the risk of infectious keratitis in the postoperative period. We present a case of a 22-year-old man with infectious keratitis in his left eye 8 days after an uneventful bilateral tPRK. A 2 mm × 5 mm anterior stromal area of corneal infiltration with a same sized overlying epithelial defect was noted at the time of presentation. His uncorrected distance visual acuity was 20/63 in his left eye. Corneal scrapings showed Bordetella bronchiseptica. The infection responded to intensive treatment with topical levofloxacin 0.5% eye drops. The final visual acuity was 20/20 in the left eye.