羟基磷灰石微晶体对培养骨细胞钙代谢的作用

通过体外研究，观察了三种不同浓度的羟基磷灰石（HA）微晶体悬液对骨细胞的钙代谢作用的影响。MC3T3-E1细胞和ROS细胞分别与1.5mg/ml,3.0mg/ml和4.5mg/ml的HA微晶体悬液混合培养，观察细胞的生长率。结果表明：中，低浓度的HA没有明显的细胞生长抑制作用，但高浓度的HA微晶体悬液有轻微的细胞生长抑制。各实验组的细胞内钙和细胞外钙的测定结果表明，细胞内外钙含量的变化与HA微晶体悬液的浓度有关，HA微晶体能直接作用于骨细胞的钙代谢，促进细胞的矿化作用。     

氟素制剂促进离体乳牙再矿化作用的比较研究

目的：比较3种常见氟素制剂对乳牙体外矿化的促进作用。评估其防龋效果。方法：36个乳牙，随机分为4组，开窗，酸蚀，1、2、3组分别涂布100g/L(NH4)2MoO2F4,380g/LAg(NH3)2F,APFLaCl33min，第4组作对照，随后置入5ml矿化液中，4d后检测矿化液中Ca^2 浓度，计算其变化并进行统计分析。结果：同对照组相比，3种氟素制剂处理组再矿化液中Ca^2 均显著减少，其中以APF-LaCl3组和380g/LAg(NH3)2F组减少最多，两组间无差异。但同100g/L(NH4)2MoO2F4组差别显著。结论：3种氟素制剂都可有效的促进乳牙体外再矿化，其中APF-LaCl3和380g/LAg(NH3)2F效果最佳，优于100g/L(NH4)2MoO2F4。     

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.     

A simple method of making an implant-level impression when presented with limited space,unfavorable implant positions,or problematic implant angulations

Making an implant-level impression for the purpose of abutment selection when implants are placed in limited space, unfavorable positions, or compromising angulations can be a time-consuming procedure. An impression procedure is presented that makes use of either prefabricated screw-retained titanium implant index copings or plastic snap-on implant index copings to help resolve problematic implant placement. Both the titanium and plastic implant index copings are easy to modify and therefore make impression procedures more predictable.     

Human periodontal ligament cell responses to recombinant human bone morphogenetic protein-2 with and without bone allografts

BACKGROUND: Recombinant human bone morphogenetic protein-2 (rhBMP-2) has been found to promote the osteoblastic differentiation of human periodontal ligament cells. Its effect depends on the delivery system used. In this study we examined the effect of rhBMP-2 on the proliferation and osteoblastic differentiation of human periodontal ligament cells cultured alone or with 3 different bone allografts. METHODS: The rhBMP-2 effect on cell proliferation and osteoblastic differentiation was examined by measuring [3H] thymidine incorporation and ALPase activity, respectively, on human periodontal ligament (hPDL) cells. Two human demineralized freeze-dried allografts of cortical (DFDBAco) and cancellous (DFBDAca) bone origin and 1 non-demineralized freeze-dried allograft (FDBA) of cancellous bone origin, derived from different tissue banks, were used to evaluate the rhBMP-2 effect on cell osteoblastic differentiation. The measurements were taken on various days. RESULTS: rhBMP-2 decreased hPDL cell proliferation. rhBMP-2 acted on the third day of the process of cell differentiation, had a specific time of action, achieved its peak effect on the fourth and fifth days, and then did not provoke any further effects. The 3 bone allografts were efficiently combined with rhBMP-2. The combination of rhBMP-2 and DFDBAco showed the effect with the longest duration. rhBMP-2, on day 4, made the inactive bone allograft more active while, on the other days, its effect was dependent on the allograft alone. CONCLUSIONS: rhBMP-2 promotes the osteoblastic differentiation of human periodontal ligament cells and decreases cell proliferation. In this study rhBMP-2 in the presence of the bone allografts tested resulted in hPDL cell differentiation.     

干燥综合征患者唾液pH值、电解质测定的诊断意义初步探讨

目的:探讨唾液生化指标测定对初步诊断干燥综合征的临床价值。方法:分为干燥综合征病变组和正常对照组,吐取法采集混合唾液,测定唾液pH值、Na 、K 浓度,计算Na /K ,Na 、K 单位时间分泌总量。t检验统计分析。结果:干燥综合征病变组唾液Na 、K 浓度、Na /K 明显高于正常对照组,与正常对照组相比,病变组K 单位时间分泌总量明显下降,pH值显著降低。Na 浓度、Na /K 敏感性、特异性均较高,pH值特异性较高,K 单位时间分泌总量敏感性、特异性一般。结论:唾液检查是一种简便、准确、无创的检查手段,干燥综合征患者唾液pH值、电解质具有特征性,其综合评定对初步筛选干燥综合征有一定临床价值。     

Occupational exposure to mercury in dentistry and pregnancy outcome

A questionnaire was mailed to dentists and dental assistants requesting information about work, health, and reproductive history. Statistical analysis of the data indicated that there were no increased rates of spontaneous abortions or congenital abnormalities in the children of men and women who were exposed to low versus high levels of mercury in a dental environment.     

Evaluation of a 4-META Porcelain Repair System

A recently introduced porcelain repair system utilizing 4-META (Etch-Free Primer with C & B-Metabond) was evaluated for bond strength to porcelain. This system purportedly eliminates hydrofluoric acid-etching and silane pretreatment. Forty porcelain specimens were prepared and treated with the 4-META repair system. A resin cylinder was bonded to the treated porcelain surface. Twenty of the specimens were tested after 24 hours while the other 20 were tested after thermocy-cling (800 cycles at 6° C to 60° C). The mean bond strengths were: 24 hours 17.4 MPa (±4.8), thermocycled 19.1 MPa (±7). Cohesive failure of the porcelain occurred in all of the specimens, both the 24 hour and the thermocycled. These bond strengths compare favorably with or exceed those of other porcelain repair systems tested in other studies.     

明朝金属全冠及其粘接剂之成分分析

目的考察我国明朝（公元１３６８～１６４４年）的口腔修复技术，并为我国口腔医学史提供一些细节资料。方法借助目测及扫描电镜能谱分析，对江苏武进博物馆编号为０７５４／００４６的二颗馆藏明朝人类牙齿冠部的金属全冠及其粘接剂作了初步成分分析。结果考古分析表明，二牙系明朝嘉靖至万历年间（公元１５００～１６００年）遗物，均为上前牙且无牙体制备痕迹，金属全冠系锤造后焊接而成。能谱分析显示二金属冠分别含金７９３３％及８５８６％，含铜２０６７％及１４１４％，粘接剂内含锌元素。结论我国明朝已能利用高硬度铜金合金及粘接材料修复牙体缺损，表明我国明朝已有较成熟的口腔修复技术。