Relationship of implant stability and bone density derived from computerized tomography images

Background and Purpose

Implant stability is one of the most important factors influencing osseointegration. Using stereolithographical guides for maximizing precision, this study aimed at investigating the relationship between implant stability and bone density derived from computerized tomography analysis.

Materials and Methods

One hundred ninety‐five implants were placed in 48 patients using digitally designed stereolithographical surgical guides. Ninety‐five implants were placed using a mucosa supported guide and 100 implants were placed using a bone supported guide. Implant stability was measured by means of resonance frequency analysis (RFA) and damping capacity assessment (Periotest, PTV). Bone density (Hounsfield units) was measured at different regions of interest (ROI) and cortex thickness was measured around each implant.

Results

Implant stability correlated significantly with the different ROI. The best correlation for RFA was obtained for the spongious bone ROI (r = .64) and PTV best correlated with the coronal cortex density (r = ?.41). Shorter implants (9 mm) had a significantly lower primary stability than longer implants (11, 13, 15 mm). Primary stability was also significantly higher in 4 mm diameter implants than in 3.5 mm diameter implants. A formula for the prediction of primary stability based on the different variables investigated was developed.

Conclusions

Bone density and cortex thickness have a significant influence on implant primary stability. Longer and wider implants reached higher primary stability than shorter and narrower implants. These correlations lose their significance after osseointegration has taken place. Implant stability can be predicted based on an preoperative analysis of bone characteristics.     

Piezoelectric surgery versus conventional drilling for implant site preparation: a meta-analysis

Purpose

To answer the PICO question: “Among patients to whom an implant is placed, does the piezoelectric surgery (PS) compared to the conventional drilling (CS) achieve higher implant stability, increase surgical time or improve implant survival rate?”

牛磺酸纳米乳的制备及稳定性考察

[目的]研究牛磺酸纳米乳的处方、制备及稳定性考察。[方法]通过滴定法绘制伪三元相图,根据相图优选处方,并初步考察牛磺酸纳米乳的稳定性、粒径分布和理化性质。[结果]确定纳米乳处方为十四酸异丙酯(IPM):司盘-80∶吐温-80∶水=4∶4∶6∶1。牛磺酸纳米乳平均粒径为30.8 nm。[结论]牛磺酸纳米乳制备方法简单,性质稳定。     

瑞士球训练为中心的组合力量训练与传统阻力训练对人体平衡能力作用的比较

目的:比较以瑞士球训练为中心的组合力量训练与传统阻力训练对人体平衡能力的影响。方法:选取30名普通女大学生,随机分为实验组和对照组,每组15人。实验共进行10周,每周3次,每次60分钟。实验组进行以瑞士球、平衡盘、悬吊等为中心的组合力量训练,对照组进行以杠铃、哑铃、组合力量训练器为主的传统阻力训练。实验前后,运用BIODEX动态平衡系统分别测试并分析两组受试者睁眼和闭眼状态下的动态平衡能力,测试难度系数8级。结果:10周训练结束后,两组受试者睁眼和闭眼状态下的动态测试总体稳定指数(OSI)、前后方向稳定指数(API)和左右方向稳定指数(RLI)较实验前均发生不同程度的变化。与训练前相比,实验组受试者睁眼和闭眼状态下双脚OSI、API、RLI显著降低(P<0.05),降低幅度分别为45.2%、48.2%、53.1%和65.8%、73.9%、58.5%;对照组实验后睁眼和闭眼状态下OSI、API、RLI较实验前也有所变化,降低幅度分别为27.0%、-5.6%、0%和2.3%、2.0%、-6.6%,但无统计学意义(P>0.05)。两组受试者实验后三项指标组间比较差异显著(P<0.05)。实验后实验组受试者睁眼和闭眼状态下OSI、API、RLI三项指标分别为0.57±0.26、0.44±0.26、0.30±0.16和0.94±0.75、0.72±0.62、0.59±0.41;对照组分别为0.89±0.2、0.75±0.29、0.77±0.56和2.09±1.32、1.93±1.53、1.29±0.66,睁眼和闭眼状态下三项指标比较差异显著(P<0.05)。结论:相对于传统力量训练方法,以瑞士球训练为中心的组合力量训练对于增强人体平衡能力、提高不稳定状态下的姿态保持具有显著作用。     

肘关节内侧副韧带前束重建的生物力学研究

目的通过测量肘关节内侧副韧带(medial collateral ligament,MCL)前束生物力学指标,探讨前束完整及重建后对肘关节外翻稳定性的影响,评价采用人工肌腱、界面螺钉重建MCL前束疗效。方法成人完整上肢标本12具,男8具,女4具;左、右侧各6具;制成肘关节"骨-韧带"标本。采用生物力学及压敏胶片测量方法,分别测量MCL前束完整(对照组)及使用人工肌腱、界面螺钉重建后(实验组)肘关节屈曲0、30、60、90°时关节外翻松弛度、肱尺关节受力面积及肘关节内压强。结果两组在肘关节不同屈曲角度下,组内及组间关节松弛度比较,差异均无统计学意义(P>0.05)。除肘关节屈曲0°时两组肘关节压强小于其余屈曲角度(P<0.05),及对照组小于实验组(P<0.05)外,两组其余各角度组内及组间比较差异均无统计学意义(P>0.05)。除对照组内肘关节屈曲0°时肱尺关节受力面积大于其余屈曲角度(P<0.05)外,两组其余各角度组内及组间比较差异均无统计学意义(P>0.05)。结论 MCL前束对维持肘关节外翻稳定性具有重要意义,金属界面螺钉加人工肌腱重建后可即刻恢复内侧稳定。     

重建椎体完整性和稳定性在胸腰椎骨折中的应用

目的探讨胸腰段骨折重建椎体完整性和稳定性的方法及临床意义。方法 35例胸腰椎骨折全部行后路椎体撑开复位病椎内植骨联合RF短节段内固定手术,平均15个月取出内固定。结果 35例患者平均随访19个月,X线片示全部骨性愈合,即刻矫正满意,远期矫正无丢失,采用F ranke l脊髓损伤分级进行神经功能评定有不同程度的恢复。结论胸腰段骨折经伤椎椎弓根椎体撑开复位椎体内植骨联合RF内固定以重建椎体的完整性和稳定性,可有效防止矫正度丢失、内固定松动断裂、晚期脊柱不稳及继发椎管狭窄等并发症,而且创伤小,效果可靠,操作简便。