RGD肽修饰壳聚糖作为种植体表面基因载体的研究

目的 探索改善钛种植体表面处理的新方法,提高种植体植入后成骨效率。方法 将RGD肽与壳聚糖（CS）通过酰化反应发生偶联形成RGD-CS,采用复凝聚法制备RGD-CS/pDNA复合体,并将RGD-CS/pDNA复合体接枝到经物理、生化处理后的纯钛表面。采用红外光谱仪和元素分析仪对 RGD-CS进行化学结构的表征检测,凝胶电泳阻滞试验结合原子力显微镜观察RGD-CS对质粒的包裹情况及RGD-CS/pDNA复合体的形态, EB染色法检测钛片表面 RGD-CS/pDNA复合体的接枝效果。结果 红外光谱检测结合元素分析表明,CS和RGD肽偶联成功;凝胶电泳阻滞试验结合原子力显微镜观察表明,在N/P≥2时,RGD-CS与pDNA完全复合,RGD-CS/pDNA复合体呈类球形;EB染色表明RGD-CS/pDNA复合体接枝钛片成功。结论 经RGD肽修饰的壳聚糖可以携带 pDNA作为钛种植体表面质粒包装的载体。     

钛种植体表面新型抗菌涂层预防种植术后早期感染的动物实验研究

目的：通过在犬下颌骨内植入种植体,观察新型抗菌涂层预防种植术后早期感染的实际效果。方法：选择2岁龄牙周健康的雄性Beagle犬4只,拔除双侧下颌第三前磨牙,并在近远中根拔牙窝内预备种植窝行即刻种植术。随机选取2只植入载有新型抗菌涂层的种植体作为实验组,另外2只植入仅微弧氧化处理的种植体作为对照组,并用丝线在所有种植体的颈部结扎,术后给予高糖软食,诱导种植体周围发生早期感染。结扎2个月后对种植体周进行临床指标检查和X线摄片,通过扫描电镜观察种植体／骨组织界面。结果：2个月后,实验组种植体周的临床检查指标明显低于对照组护〈0．05）。X线检查可见：实验组种植体周围无明显的牙槽骨吸收和透射影像,对照组种植体周围可见明显的骨吸收和裂隙状透射影像。扫描电镜观察可见：实验组种植体／骨界面结合较好,未见明显间隙,而对照组种植体与骨组织之间存在明显的间隙。结论：在钛种植体表面构建的新型抗菌涂层具有显著的预防种植术后早期感染的效果。     

不同表面处理对纯钛的耐腐蚀性研究

目的：研究不同表面处理方式对纯钛耐腐蚀性的影响。方法：制作纯钛试件36件,分别进行机械抛光和电解抛光后,浸泡于不同氟浓度(0%、0.05%、0.2%)人工唾液中,(37.0±1.0)℃浸泡4周,测量浸泡前后表面粗糙度并观察表面形貌。结果：浸泡前后电解抛光组表面粗糙度均小于机械抛光组,差异有统计学意义(P<0.01);浸泡后纯钛表面粗糙度随氟浓度升高而增加。无氟存在时浸泡前后两组差异无统计学意义(P>0.05),加入氟后均与前组差异有统计学意义(P<0.01),电解抛光组与机械抛光组组间比较差异均有统计学意义(P<0.01)。显微镜下观察其表面形貌与粗糙度值结果一致。结论：电解抛光方式的耐腐蚀性优于机械抛光;氟离子对纯钛具有腐蚀性;高氟制品对纯钛的耐腐蚀性影响较大,选用纯钛修复体的患者,建议电解抛光后戴入口内。     

酸蚀及微弧氧化对钛表面处理后与瓷结合强度的实验研究

目的：研究酸蚀和微弧氧化单独或联合应用对纯钛表面处理后进行烤瓷,观察其表面粗糙度并分析其钛瓷结合强度。方法：将50个纯钛试片（25mm×5mmx0．5mm）随机均分为5组,表面用碳化硅砂纸抛光后110μmA12O3进行喷砂处理,再进行喷砂、酸蚀、微弧氧化、酸蚀后微弧氧化及微弧氧化后酸蚀处理分别为A到E组,用粗糙度测试仪测量各组的粗糙度值并进行统计学分析,扫描电镜观察试件的表面形貌。行瓷粉烧结（厚度控制在1mm）,然后对钛瓷间的三点弯曲结合强度进行测试并进行统计学分析,用扫描电镜观察钛瓷分离面的的表面形貌。结果：酸蚀使纹路更清晰,粗糙度增加。C组纯钛表面形成许多孔洞,孔洞较大,大小基本一致。C组除大孔洞外还存在许多小孔洞,均匀致密。D组表面孔洞大小不一,较致密,存在凹陷,边缘不规则,个别相邻孔洞之间可见微裂纹。与喷砂相比,微弧氧化处理使纯钛与瓷的结合强度差异有统计学意义（P〈0．05）,而酸蚀处理的钛表面与瓷的结合强度增加,但与对照组差异无统计学意义（P〉0．05）。结论：酸蚀和微弧氧化联合处理与单独微弧氧化处理钛瓷间的结合强度差异无统计学意义,说明微弧氧化处理更利于钛瓷间的结合。     

A comparative study of gold UCLA-type and CAD/CAM titanium implant abutments

PURPOSE

The aim of this study was to evaluate the interface accuracy of computer-assisted designed and manufactured (CAD/CAM) titanium abutments and implant fixture compared to gold-cast UCLA abutments.

MATERIALS AND METHODS

An external connection implant system (Mark III, n=10) and an internal connection implant system (Replace Select, n=10) were used, 5 of each group were connected to milled titanium abutment and the rest were connected to the gold-cast UCLA abutments. The implant fixture and abutment were tightened to torque of 35 Ncm using a digital torque gauge, and initial detorque values were measured 10 minutes after tightening. To mimic the mastication, a cyclic loading was applied at 14 Hz for one million cycles, with the stress amplitude range being within 0 N to 100 N. After the cyclic loading, detorque values were measured again. The fixture-abutment gaps were measured under a microscope and recorded with an accuracy of ±0.1 µm at 50 points.

RESULTS

Initial detorque values of milled abutment were significantly higher than those of cast abutment (P<.05). Detorque values after one million dynamic cyclic loadings were not significantly different (P>.05). After cyclic loading, detorque values of cast abutment increased, but those of milled abutment decreased (P<.05). There was no significant difference of gap dimension between the milled abutment group and the cast abutment group after cyclic loading.

CONCLUSION

In conclusion, CAD/CAM milled titanium abutment can be fabricated with sufficient accuracy to permit screw joint stability between abutment and fixture comparable to that of the traditional gold cast UCLA abutment.     

纳米二氧化钛神经毒性的研究进展

纳米二氧化钛（TiO₂ NPs）能屏蔽紫外线,是一种具有良好分散性和耐候性的白色疏松粉末,常作为新型纳米材料应用于化妆品、功能纤维、塑料、涂料、油漆等行业,因此可从呼吸道、消化道、皮肤接触等多种途径进入人体。近年来,随着TiO₂ NPs在各领域的应用,其安全性和其潜在危害逐渐得到了人们的关注和重视。该文结合目前TiO2 NPs神经毒性的各类相关研究,从其理化性质、暴露途径和神经毒性机制方面对TiO₂ NPs的安全性进行评价,并进行讨论、总结与展望。