纳米磷酸钙/氧化锆骨组织工程支架体内降解的实验研究

目的研究纳米磷酸钙/氧化锆骨组织工程支架材料体内降解特性,为进一步构建组织工程化纳米人工骨提供研究依据。方法制作兔股部肌袋,将灭菌的纳米磷酸钙/氧化锆骨组织工程支架材料植入肌袋内,在植入4周、8周、12周、16周时取材通过大体、组织学、扫描电镜观察材料降解情况,同时将材料取出后煅烧,测量残余无机物含量,判断降解的量,同时进行X线衍射实验,测量残余材料的组成。结果材料植入8周内降解较慢,生物力学强度减低不明显,12周时降解加速,材料强度明显减低,16周时新骨形成明显,降解残余材料分布于新形成的骨组织内部,X线衍射发现12周时材料内有羟基磷灰石成分出现,提示有新骨形成,16周时羟基磷灰石成分明显增多。结论纳米磷酸钙/氧化锆骨组织工程支架材料具有较好的降解性和生物相容性,具有诱导成骨作用,可作为骨组织工程的支架材料。     

口腔修复陶瓷材料的磨损性能北大核心

背景:陶瓷材料因具有优良的机械性能、与口腔组织良好的生物相容性及高度美观性广泛应用于口腔修复领域,良好的磨损性能对修复体临床应用有重要意义。目的:综述口腔修复陶瓷材料磨损性能机制及临床研究,以期为临床选择适宜的陶瓷材料提供思路。方法:应用计算机在PubMed和Web of Science数据库检索在2016年1月至2021年4月期间涉及口腔修复陶瓷材料磨损性能的相关研究。英文检索词为“dental ceramic material,wear property”,最终共纳入36篇文献进行分析。结果与结论:①全瓷材料自身耐磨性均高于树脂陶瓷复合材料,全瓷材料中氧化锆陶瓷磨损性能最佳,美学性能较弱。②玻璃陶瓷中氧化锆加强型硅酸锂玻璃陶瓷磨损性能较好,但应用时间较短,长期疗效还有待更多的研究证实。③树脂陶瓷复合材料中树脂纳米陶瓷材料磨损性能优于聚合物渗透陶瓷。④在后牙区全冠修复可选择氧化锆陶瓷,前牙区全冠修复可以根据患者的美学需求选择高透性氧化锆陶瓷或玻璃陶瓷。⑤贴面、嵌体和高嵌体修复可选择长石瓷、玻璃陶瓷和树脂陶瓷复合材料,但树脂陶瓷复合材料耐磨性差,需避免用于高应力承载区。⑥对牙本质暴露、氟斑牙和牙齿酸蚀症患者可考虑树脂纳米陶瓷材料,但这类患者适宜的陶瓷材料相关研究较少。⑦表面粗糙度对陶瓷材料的磨损性能有显著影响,临床口腔修复应用中采用良好的抛光表面可提高陶瓷材料磨损性能,而且对修复体进行定期复查也至关重要。     

Clinical assessment of enamel wear caused by monolithic zirconia crowns

The purpose of this study was to measure enamel wear caused by antagonistic monolithic zirconia crowns and to compare this with enamel wear caused by contralateral natural antagonists. Twenty monolithic zirconia full molar crowns were placed in 20 patients. Patients with high activity of the masseter muscle at night (bruxism) were excluded. For analysis of wear, vinylpolysiloxane impressions were prepared after crown incorporation and at 6‐, 12‐, and 24‐month follow‐up. Wear of the occlusal contact areas of the crowns, of their natural antagonists, and of two contralateral natural antagonists (control teeth) was measured by use of plaster replicas and a 3D laser‐scanning device. Differences of wear between the zirconia crown antagonists and the control teeth were investigated by means of two‐sided paired Student's t‐tests and linear regression analysis. After 2 years, mean vertical loss was 46 μm for enamel opposed to zirconia, 19–26 μm for contralateral control teeth and 14 μm for zirconia crowns. Maximum vertical loss was 151 μm for enamel opposed to zirconia, 75–115 μm for control teeth and 60 μm for zirconia crowns. Statistical analysis revealed significant differences between wear of enamel by zirconia‐opposed teeth and by control teeth. Gender, which significantly affected wear, was identified as a possible confounder. Monolithic zirconia crowns generated more wear of opposed enamel than did natural teeth. Because of the greater wear caused by other dental ceramics, the use of monolithic zirconia crowns may be justified.     

Inlay‐retained cantilever fixed dental prostheses to substitute a single premolar: impact of zirconia framework design after dynamic loading

The purpose of this in‐vitro study was to evaluate the influence of the framework design on the durability of inlay‐retained cantilever fixed dental prostheses (IR‐FDPs), made from zirconia ceramic, after artificial ageing. Forty‐eight caries‐free human premolars were prepared as abutments for all‐ceramic cantilevered IR‐FDPs using six framework designs: occlusal–distal (OD) inlay, OD inlay with an oral retainer wing, OD inlay with two retainer wings, mesial–occlusal–distal (MOD) inlay, MOD inlay with an oral retainer ring, and veneer partial coping with a distal box (VB). Zirconia IR‐FDPs were fabricated via computer‐aided design/computer‐aided manufacturing (CAD/CAM) technology. The bonding surfaces were air‐abraded (50 μm alumina/0.1 MPa), and the frameworks were bonded with adhesive resin cement. Specimens were stored for 150 d in a 37°C water bath during which they were thermocycled between 5 and 55°C for 37,500 cycles; thereafter, they were exposed to 600,000 cycles of dynamic loading with a 5‐kg load in a chewing simulator. All surviving specimens were loaded onto the pontic and tested until failure using a universal testing machine. The mean failure load of the groups ranged from 260.8 to 746.7 N. Statistical analysis showed that both MOD groups exhibited significantly higher failure loads compared with the other groups (i.e. the three OD groups and the VB group) and that there was no significant difference in the failure load among the OD groups and the VB group. In conclusion, zirconia IR‐FDPs with a modified design exhibited promising failure modes.