Physicochemical evaluation of silica-glass fiber reinforced polymers for prosthodontic applications

This investigation was designed to formulate silica-glass fiber reinforced polymeric materials. Fused silica-glass fibers were chosen for the study. They were heat-treated at various temperatures (500 degrees C, 800 degrees C and 1100 degrees C), silanized, sized and incorporated in two modified resin mixtures (A and B). The flexural properties in dry and wet conditions were tested and statistically analyzed, and the content of residual methyl methacrylate (MMA) monomer, dimensional changes with temperature, water sorption and solubility were determined. Woven fibers [36.9% (wt/wt)], heat-treated at 500 degrees C, gave the highest strength values for the polymeric composites (an ultimate transverse strength of 200 Mpa and a flexural modulus of 10 GPa) compared with the fibers heat-treated at other temperatures. There was no statistically significant difference in the measured flexural properties between resins A and B regarding fiber treatment and water storage time. These fiber composites had a small quantity of residual MMA content [0.37 +/- 0.007% (wt/wt)] and very low water solubility, indicating good biocompatibility. It was suggested that silica-glass fibers could be used for reinforcement as a result of their anticipated good qualities in aqueous environments, such as the oral environment.     

产黑色素普氏菌DNA探针的制备及鉴定

本研究旨在应用DNA探针杂交技术快速检测产黑色素普氏菌、利用产黑色素普氏菌经酚抽取全染色体DNA，并以缺口转移法标记32P，制备探针。结果证实，该探针能够检测到膜上2×104的纯菌；当产黑色素普氏菌和中间普氏菌以不同比例混合点膜时，该探针能够检测到占混合菌群17％的目的菌；与口腔感染常见菌株杂交，未见交叉反应。     

口腔念珠菌带菌与感染状态分离菌株的RAPD分析

目的 :研究念珠菌种之间及不同来源白念珠菌菌株之间的基因型相关性。方法 :对口腔白念珠菌病原菌、共生菌及非白念病原菌分别进行表型和RAPD分析。结果 :白念珠菌与非白念珠菌的RAPD带型存在差异 ,相似系数在 5 1.7%。共生菌与病原菌RAPD带型未见差异。白念珠菌种内相似系数大于 70 % ,菌株间存在DNA多态性。结论 :共生白念珠菌与病原菌未见RAPD带型差别 ,提示对口腔念珠菌病的防治应重视宿主因素在发病中的作用。     

Non-viral-mediated gene therapy approaches for bone repair

OBJECTIVES: Bone repair strategies continue to be developed for alternatives to autografting, allogeneic implants of banked bone, and other bone substitutes. Efforts have included the delivery of potent growth and/or differentiation factors and the use of gene therapy. For bone regeneration, gene therapy is the delivery, uptake and expression of DNA that has been localized to a wound bed. The objective of the current study is to investigate methods to enhance non-viral-mediated means of gene uptake and expression for use in bone regeneration. METHODS: Several types of DNA-polymer complexes, either applied directly to baby hamster kidney (BHK) cells, or released from a porous, resorbable gene-activated matrix (GAM), were evaluated in vitro for their ability to transfect cells with a circular plasmid DNA construct expressing green fluorescent protein. Complexes included conjugates containing a lipophilic reagent, liposomes, poly-ethyl-oxazoline, and poly-ethyleneimine (PEI). Data were subjected to analysis of variance and Fisher's protected least significant difference for multiple comparisons with significance established at p < 0.05. RESULTS: Transfection efficiencies of the liposome and PEI complexes improved in vitro when released from resorbable GAMs. The lipophilic reagent FuGene 6 demonstrated abundant uptake and expression in the initial 1- and 2-day evaluation periods. In contrast, the DNA-liposome and PEI GAM complexes demonstrated a sustained release, uptake and expression by the BHK cells at the 2-, 4-, and 7-day, and 4- and 7-day evaluation intervals, respectively. CONCLUSION: GAM technology appears to improve the functional stability and release duration of incorporated DNA-polymer complexes in the present in vitro studies. The ongoing objective of our research is to develop a localized treatment to improve the uptake and expression of plasmid DNA by non-viral-mediated gene therapy.     

填料含量对牙科光固化粘结剂残余单体量的影响

目的：探讨填料的加入对牙科光固化粘结剂聚合转化度的影响。方法：采用高效液相色谱仪测试了不同填料含量的光固化粘结剂固化后的残余单体量。结果：无填料粘接剂残余单体量最大，随填料含量增加而减少；照射６０ｓ，９．１％组显示最小。结论：填料含量５％（ｗｔ），照射６０ｓ较适宜     

The influence of periodontitis on the subgingival flora around implants in partially edentulous patients

The hypothesis that teeth act as reservoirs of micro‐organisms for the colonization of oral implants has recently been stated several times. The present study aimed at examining, in partially edentulous patients with severe periodontitis, whether pockets around teeth and implants harbored a comparable micro‐flora. In 6 patients (3 with refractory periodontitis and 3 with advanced chronic adult periodontitis), plaque samples were taken from a deep and shallow pocket around both teeth and implants for differential phase contrast microscopy and DNA probe analysis. The results showed important differences in the sub‐gingival flora between the 2 disease groups, as well as between deep and shallow pockets, around both implants and teeth. On the other hand, when pockets around teeth and implants with equal depths were compared a striking similarity was observed in the microbial composition. These observations confirm the hypothesis that pockets around teeth act as a reservoir and highlight the importance of periodontal health when oral implants are planned.     

Comprehensive gene expression analysis in human periodontal ligaments of the mandibular third molars performing vertical movement and the maxillary second premolars with occlusal contact

OBJECTIVES: The periodontal ligament (PDL) is thought to be an important tissue in vertical movement during tooth eruption, but the precise molecular mechanism is not known. Thereto, comprehensive gene expression was analyzed in human PDL of mandibular third molars performing vertical movement and maxillary second premolars with occlusal contact. DESIGN: The expression profile of 9,243 genes in the PDL of one subject was compared between vertically moving third molars and second premolars with occlusal contact by DNA microarray. RESULTS: The expression of 27 genes showed more than a 10-fold difference between third molars and second premolars. The expression of CALB1 (encoding calbindin 1), CYP26A1 (encoding cytochrome P450, family 26, subfamily A, polypeptide 1), SPOCK3 (encoding testican-3), CCK (encoding cholecystokinin) and SCRG1 (encoding scrapie responsive protein 1) was more than 30-fold higher in PDLs of the third molars than the second premolars. CALB1 is reported to increase at the pressure side of PDL during experimental orthodontic tooth movement in rats. Interestingly, in this study, CALB1 expression showed the largest difference. In contrast, CRCT1 (encoding cysteine-rich C-terminal 1), SPRP3 (encoding small proline-rich protein 3), IL8 (encoding interleukin 8) and MMP12 (encoding matrix metalloproteinase 12) showed more than 100-fold higher expression in PDLs of the second premolars than the third molars. CONCLUSION: The present comprehensive gene expression in PDLs provides new insights into the molecular mechanism during the vertical tooth movement.     

The effects of fixed and removable implant-stabilised prostheses on posterior mandibular residual ridge resorption

Abstract: This study investigated the change over time in the area of the posterior mandibular residual ridge in patients wearing either i) mandibular overdentures stabilised by two implants (Brånemark System; Nobel Biocare, Göteborg, Sweden) connected by a bar, or ii) mandibular fixed cantilever prostheses stabilised on five or six implants. Proportional measurements were made in order to compare the area of the residual ridge with an area of bone uninfluenced by resorption. Measurements were made by digitising tracings of panoramic radiographs that were taken shortly after implant insertion and up to seven years later. With the use of overdentures, the posterior bone area index reduced by a mean of 1.1% per annum, while a mean bone area index increase of 1.6% per annum was demonstrated in association with fixed prostheses. A multiple linear regression model was fitted to predict the change in posterior area from type of prosthesis, gender, age, years of edentulism and initial height of the mandible. The model was only significant for initial height of mandible (P = 0.04) and type of prosthesis (P = 0.0001). In conclusion, patients rehabilitated with implant‐stabilised mandibular overdentures demonstrated low rates of posterior mandibular residual ridge resorption, while patients rehabilitated with implant‐stabilised mandibular fixed cantilever prostheses demonstrated bone apposition in the same area.     

X连锁无汗性外胚叶发育不全家系ED1基因的突变检测

目的探讨国内X连锁无汗性外胚叶发育不全家系中ED1基因的突变情况，为该病的遗传咨询、产前诊断、确诊携带者提供依据。方法收集2个X连锁无汗性外胚叶发育不全家系及1个散发患者的外周血样本，盐析法提取基因组DNA，采用聚合酶链反应（polymerase chain reaction，PCR）和直接测序对ED1基因进行突变检测。结果家系一患者ED1基因第9外显子发生错义突变（1045G〉A），家系二和散发患者ED1基因第3外显子发生错义突变，分别为467G〉A和466C〉T。结论ED1基因的错义突变可导致X连锁无汗性外胚叶发育不全。这3个突变与国外学者的报道一致。     

The use of DNA probes to examine the distribution of subgingival species in subjects with different levels of periodontal destruction

The present investigation examined the distribution of 14 subgingival species at a total of 2299 sites in 90 subjects with different levels of periodontal destruction. Subgingival plaque samples taken from the mesial aspect of each tooth were anaerobically dispersed, diluted and plated on non selective media. After anaerobic incubation, colonies were lifted to nylon filters and specific species detected using digoxygenin-labeled whole chromosomal DNA probes. The mean total viable count for all sites in all subjects was 8.3 x 10(6). The probes accounted for an average of 27.8% of the total viable count. The % of subjects in which each species was detected was as follows; V. parvula, 98; B. intermedius I, 98; S. sanguis II, 96; B. intermedius II, 95; C. ochracea, 94; B. gingivalis, 91; S. sanguis I, 85; W. recta, 83; F. nucleatum ss. vincentii, 82; S. intermedius, 80; B. forsythus, 76; P. micros, 74; A. actinomycetemcomitans serotype a, 62 and A. actinomycetemcomitans serotype b, 52. The % of sites colonized by each of the 14 test species varied considerably within different subjects. The median number of sites colonized by different species ranged from 3.6% for A. actinomycetemcomitans serotype b to 43.5% for V. parvula. In half the subjects, the mean % of the total viable counts for each of the test species was less than 4%. When subjects were divided on the basis of % of sites at baseline with greater than 3 mm attachment loss, the 14 probes accounted for 29.9% of the microbiota in the localized disease group and 25% in the widespread disease group.(ABSTRACT TRUNCATED AT 250 WORDS)