三维图像融合技术评价上颌全牙列种植固定修复前后的鼻唇软组织形态变化

目的:探讨利用面部与义齿三维(three dimensional,3D)图像融合方法评估全牙列种植固定修复前后鼻唇区软组织形态变化的可行性。方法:选择于北京大学口腔医院种植科就诊的上颌无牙颌患者共12例(女性4例、男性8例),平均年龄(54.82±5.50)岁(45~62岁)。于上颌植入4~6枚种植体,6个月后为患者佩戴全牙列固定义齿,捕捉患者佩戴义齿前后的3D面相及义齿形态数据。将三维数据置于同一坐标系中,对义齿和软组织标志点进行测量,分别比较各标志点[左口角点(cheilion left, CHL)、右口角点(cheilion right, CHR)、左唇峰点(crista philtri left,CPHL)、右唇峰点(crista philtri right, CPHR)、上唇缘点(labrale superius, LS)、鼻下点(subnasale, SN)、口裂正中点(stomion,STO)、上中切牙点(upper incisor, UI)、义齿上边缘顶点(F-point, F)]的位移量及标志点间线距[人中长度(SN-LS)、双唇峰间距(CPHR-CPHL)、口裂宽(CHR-CHL)、上唇红高度(LS-STO)]变化。结果:义齿与软组织拟合后,义齿上边缘顶点与鼻下点直线距离(F-SN)三次测量结果的一致性检验显示该方法可重复性好,组内相关系数(intraclass correlation coefficient, ICC)为0.983 (95%CI:0.957~0.995)。佩戴义齿后,软组织各标志点均发生前徙变化,鼻底区域变化最小,SN前后方向上的位移为(0.61±0.44) mm,LS前后向位移为(3.12±1.38) mm。在垂直方向上,SN、LS、CPHL、CPHR均向上移动,STO、CHL、CHR向下方少量移动。除SN-LS略微减小外,CHR-CHL、CPHR-CPHL、LS-STO均增大(P<0.01)。SN与F、LS与UI的Z轴坐标值均呈现高度相关(r=0.904 3、r=0.958 4)。结论:三维面像与义齿图像融合方法可重复性好,经该方法检测,义齿与软组织标志点的前后向位移之间存在高度相关性。     

北京市地区牙体牙髓医生需要量的研究

目的 预测不同模式下龋病治疗所需要牙科人力，进行供震匹配分析。方法 分层、整群、随机抽取北京市区实际人口1517人进行龋病治疗需要与需求状况调查，工时测定采用现场写实法与经验估计法，利用卫生服务需要与需求法计算牙体髓医生需要量。结果 龋病患病率64.9％，57.5％的人有牙体牙髓治疗需要。一年就诊率20.2％，潜在需求64.9％。预测到2010年的配置参考范围为987－1628人（WHO工作时间）和1029－1697人（CHcT工作时间）。结论 龋病治疗需要与有效需求之间有较大差距，并将继续扩大，牙体牙髓医生供不应求，牙体牙髓医生的培养应是牙科人力发展的增量投向之一。     

Treatment of persistent corneal epithelial defect by autologous serum application.

OBJECTIVE: To evaluate the efficacy of autologous serum application for the treatment of persistent epithelial defect. DESIGN: Prospective, clinical, noncomparative case series. PARTICIPANTS: A total of 16 eyes were studied. INTERVENTION: Autologous serum was prepared from the patients and diluted to 20% by saline. The patients were instructed to use the autologous serum six to ten times a day. The concentration of vitamin A, epidermal growth factor (EGF), and transforming growth factor-beta (TGF-beta) was measured at 1 week and 1 month stored in the refrigerator and 1 month and 3 months in the freezer. MAIN OUTCOME MEASURES: Time to closure of epithelial defect. RESULTS: Vitamin A, EGF, and TGF-beta were stable during the 1 month in the refrigerator and 3 months in the freezer. Among 16 persistent epithelial defects, 7 (43.8%) healed within 2 weeks, 3 (18.8%) healed within 1 month, and the remaining 6 (37.5%) did not respond within 1 month. No apparent side effect of autologous serum application was observed. CONCLUSIONS: Autologous serum application healed 43.8% of persistent defect within 2 weeks and 62.5% within 1 month.     

组织工程构建人工食管的初步实验研究

目的：初步探讨组织工程制备可降解人工食管的可行性。方法：体外分离、培养、扩增新生牛食管上皮细胞，接种于海绵状胶原蛋白-壳聚糖膜上，然后移植入裸鼠背阔肌表面，通过组织学及扫描、透射电镜观察食管上皮细胞在体内外的增殖与分化情况。结果：培养的新生牛食管上皮细胞在胶原蛋白-壳聚糖膜表面生长良好，食管上皮细胞-胶原蛋白-壳聚糖膜复合物植入裸鼠背阔肌表面2周，食管上皮细胞可进一步分化至10层，术后4周胶原蛋白-壳聚糖膜已被降解吸收。结论：海绵状胶原蛋白-壳聚糖膜是组织工程构建可降解人工食管的优良基质材料。     

氟保护漆的释放研究

目的：观察氟保护漆在去离子水中的释放情况。方法：采用氟离子选择电极法。结果；在整个10天的实验期间，氟保护漆都释放一定量的氟，且随浸泡时间延长稀释出量逐渐下降。结论：氟保护漆释氟主要发生在第1小时，同时在一定时期内能缓慢持续释放到周围环境中，具有一定的防龋潜力。     

Effects of background suppression of gamma counts on signal estimation

Gamma detectors at border crossings are intended to detect illicit nuclear material. One of their performance challenges is the fact that vehicles suppress the natural background and, thus, potentially reduce probability of detection of threat items. Here we test several methods to adjust the detection to background suppression in the context of signal estimation.We show that, for the small-to-moderate suppression magnitudes, suppression adjustment leads to higher detection probability. However, for signals triggering alarm without an adjustment, adjustment does not improve estimation of the signal location, only moderately improves estimation of the signal magnitude, and does not improve estimation of the signal width.     

The association between osteocalcin gene polymorphism and dental fluorosis among children exposed to fluoride in People's Republic of China

Excessive fluoride intake has been shown to affect dentin and cementum mineralization throughout life. Some studies indicated that a HindIII polymorphism, of osteocalcin (OC) gene, was associated with bone metabolism-related diseases. Therefore, it is possible that the variation in OC genotypes will be associated with dental fluorosis (DF) status and/or serum caciotropic hormone level. A case-control study was conducted among children aged 8–12 years in Henan Province, PR China to investigate the association between dental fluorosis, serum calciotropic hormone level, and polymorphisms in the OC gene. HindIII polymorphism in OC gene was genotyped using the PCR-RFLP procedure. OC and calcitonin (CT) level in serum was detected using radioimmunoassay. No significant difference was observed for OC HindIII genotypes among the cases with dental fluorosis, the controls from endemic fluorosis area (EFA) and the controls from non-endemic fluorosis area (NEFA). A significant negative correlation was observed between serum calcium and OC level. No significant relationship was found between OC HindIII polymorphisms and the level of OC and CT. In conclusion, OC HindIII polymorphisms may not be a useful genetic marker for differential risk of dental fluorosis among children in PR China.     

Effect of Solution Phase Composition on the Interaction Between Aqueous Model Solutes and Polymeric Container Materials

The interaction between several marker solutes and a polyolefin laminate polymer was studied in several solutions. Solutions studied included mixtures of sodium chloride and dextrose (at concentrations more less typical of iv administration solutions) and several actual iv products [lactated Ringer's injection, Dianeal, Travasol (amino acid) injection, and alcohol/dextrose injection]. The interaction properties of the candidate container material correlated well with the solute's octanol–water partition coefficient. For nonionic species, the magnitude of the container/solution interaction was independent of solution phase composition. For the ionic test solute, solution pH, which impacts the speciation of the solute, was the only solution composition variable that significantly influenced the interaction. Thus water (or a weak buffer solution) is suggested as an appropriate model solvent for use in container compatibility evaluations involving iv-related products.     

Resorption of the mouse incisor after the application of cold to the periodontal attachment apparatus

Summary In order to study in detail the processes leading to the resorption and ankylosis of teeth after trauma, the effects of cold application on the periodontal tissues were studied in the mouse. Liquid nitrogen was applied locally to the outer surface of the lower jaw which resulted in a freezing of the incisor and its surrounding tissues. The healing processes in the damaged periodontal ligament and the accompanying phenomena of ankylosis and dental root resorption were investigated histologically at both the light and electron microscopic levels. As a result of cold application, the cells in the periodontal ligament were killed. After a few days, the ligament started to be repopulated with cells like fibroblasts and macrophages. From 3 days on, mineral crystallites were deposited along the cementum covering the lingual, mesial, and lateral surfaces of the incisor, finally resulting in a 4–6 μm thick layer. During the period of 7–12 days following cold application, this layer of mineralized material started to be phagocytosed and degraded, presumably by mononuclear cells. Finally, extensive root resorption and some ankylosis between the tooth and the laveolar bone were observed. In the resorbed areas, cells were seen which could not be distinguished from osteoclasts. In some instances, their ruffled border was in close apposition with each of the three mineralized tissues—dentin, cementum, and alveolar bone. It is hypothesized that the deposition and subsequent phagocytosis of mineralized material along the root surface may be an important factor in the initiation of dental root resorption.