改变摩擦系数对固位螺丝稳定影响的实验研究

目的探讨摩擦系数的减小对种植体固位螺丝松动的影响.方法用32Ncm将种植体和基台用固位螺丝固定在支持物上,涂布凡士林于固位螺丝表面.保持静止状态和放进超声波震荡器中1h对比,用FG-101数显力矩扳手握住螺丝刀将每个固位螺丝松动,记录测量读数最大值.结果旋松扭矩分别为静止对照组26.7±2.00Ncm,实验组25±1.15Ncm;运动对照组26.1±1.20Ncm,实验组24.8±0.70Ncm.实验组比对照组的旋松扭矩小,两两比较有统计学意义(P＜0.05).结论基台和固位螺丝之间的摩擦系数减小,预负荷增加,但更易松动.     

Stability of the implant/abutment joint in a single-tooth external-hexagon implant system: clinical and mechanical review

Rigorous efforts have recently been made to reduce the recurrence of implant/abutment joint failure in single‐tooth implant restorations. However, the current knowledge about the stability of implant/abutment joints in an external hexagon implant system is incomplete. We reviewed clinical data regarding single‐tooth implant treatment with Brånemark implants, specifically the CeraOne abutment system (Nobel Biocare AB, Göteborg, Sweden). In vitro studies on joint stability were systematically assessed. Bending overload and the presence of misfit at the implant/abutment joint interface are the critical mechanical conditions that can make the joint unstable. Appropriate joint fitness and proper alignment of the implant should be assessed, and occlusal adjustment by narrowing the restoration width and flattening cuspal inclination should be applied to avoid bending moments caused by the lateral component of occlusal forces. Sufficient clinical reports of longer duration that evaluate and verify longer‐term success of the newly manufactured joint components were unavailable.     

An abutment screw loosening study of a Diamond Like Carbon-coated CP titanium implant

The aim of this study was to quantify the extent of abutment screw loosening and thus understand the role of frictional and wear factors in abutment screw loosening by using a cyclic loading device to compare Diamond Like Carbon (DLC)-coated and non-coated implants. The properties of DLC films, including hardness, wear resistance, chemical stability, and biocompatibility, are similar to those of real diamond materials. In this study, a 1-mum thick DLC film served to protect and lubricate a layer of commercially-pure titanium affixed to the top of a dental implant (external hexagon-shaped implant). A cyclic loading force was then applied to the top of the prosthetic portion of the implants in order to determine the difference in looseness of the titanium abutment screw between ten DLC-coated implants and ten non-coated implants. The abutment screw loosening tests were performed with 100 N of force at a frequency of 20 Hz. Data indicate that implants with a DLC coating are more resistant to an applied force (P = 0.002) than are those without the coating. We hope these results will be useful for preventing implant abutment screw loosening.     

种植修复基台的选择

随着口腔种植学的飞速发展,种植基台的种类越来越多。多种多样的种植基台虽然能满足不同的临床需求,但给临床医生选择合适的修复基台造成了极大的困扰。本文旨在介绍基台设计目标、基台种类及选择标准,力求为临床医生选择种植修复基台提供一定帮助。     

Abrasion of abutment screw coated with TiN

STATEMENT OF PROBLEM

Screw loosening has been a common complication and still reported frequently.

PURPOSE

The purpose of this study was to evaluate abrasion of the implant fixture and TiN coated abutment screw after repeated delivery and removal with universal measuring microscope.

MATERIAL AND METHODS

Implant systems used for this study were Osstem and 3i. Seven pairs of implant fixtures, abutments and abutment screws for each system were selected and all the fixtures were perpendicularly mounted in liquid unsaturated polyesther with dental surveyor. After 20 times of repeated closing and opening test, the evaluation for the change of inner surface of implant and TiN-coated abutment screw, and weight loss were measured. Mann-Whitney test with SPSS statistical software for Window was applied to analyze the measurement of weight loss.

RESULTS

TiN-coated abutment screws of Osstem and 3i showed lesser loss of weight than non-coated those of Osstem and 3i (P < .05, Mann-Whitney test).

CONCLUSION

Conclusively, TiN coating of abutment screw showed better resistance to abrasion than titanium abutment screw. It was concluded that TiN coating of abutment screw would reduce the loss of preload with good abrasion resistance and low coefficient of friction, and help to maintain screw joint stability.     

反复松紧过程对种植体与基桩结合稳定性的影响

目的探讨在调整TiAdap基桩时,反复松紧过程对种植体和基桩的结合稳定性是否有影响。方法15个Branemark种植体(5RP,5NP,5WP)分别与5个TiAdapRP,5个TiAdaptNP、5个TiAdaptWP组成3组,3组分别用32N.cm、20N.cm、45N.cm扭力将种植体和基桩拧紧,然后再用扭力控制仪将两者松开,记录扭力的数据,重复5次。结果方差分析显示5次拧紧-松开过程记录的扭力第1组无显著性差异(P=0.5319);而第2、3组存在显著性差异(P=0.0084,0.0049),差别主要存在于第1次拧紧-松开过程和后4次松紧之间,后4次松紧过程之间无显著性差异。结论表明反复松紧过程对种植体和基桩结合稳定性的影响主要在第1次松紧过程。     

In vitro evaluation of the implant abutment connection sealing capability of different implant systems

This study sought to evaluate the sealing capability of the implant abutment connection of different dental implant systems. Five Nobel Replace select, Straumann and Intra-lock implants of approximately 4.5 mm diameter with their respective abutments were provided by the manufacturers. A calibration curve was determined by placing toluidine blue (TB) increments of 0.1 microL into 1.5 mL of distilled water and recording its absorbance in a spectrophotometer until reaching 0.7 microL. Then, 0.7 microL of TB was placed in the deepest portion of each implant's internal screw, the abutments were adapted to the implant according to the manufacturer's instructions and the specimens were placed in vials with 1.5 mL of distilled water. Spectrophotometric analysis was performed at 1, 3, 6, 24, 48, 72, 96 and 144 h. Statistical analysis was performed by One-way anova at 95% level of significance. The calibration curve was linear with respect to the TB amount in 1.5 microL distilled water (R(2) = 0.9961). All implant abutment systems presented an increase in absorbance as a function of time. As time elapsed in vitro, significantly higher amounts of TB was released from the Straumann and Nobel Replace Select connection systems (P < 0.0001). Leakage was significant between the groups. Despite controlled torquing, the seal between the implant body and the abutment could not be maintained in all three of the systems tested.     

A technique for repairing a loosening abutment screw for a cement-retained implant prosthesis

Prostheses may be attached to implants or implant abutments using screw retention or cementation. With the increased use of cement-retained, implant-supported restorations for the replacement of missing teeth, clinicians may choose to use a definitive cement to lute the definitive restoration. Loosening of an abutment screw is a challenging complication of cement-retained, implant-supported prosthetic restorations. Often, the abutment screw becomes loose from the implant body, whereas the crown remains cemented to the abutment. In such situations, separating the cemented crown from the underlying abutment or locating the abutment-screw access for removal of the restoration is a difficult task. The purpose of this report is to describe a simple technique for locating the abutment-screw access in the event of its loosening. The advantage of this technique is that it can facilitate easy location of the abutment screw, thus minimizing damage to the existing restoration and allowing it to be reused.     

热压瓷技术在个性化瓷种植基台中的临床应用研究

目的 探讨热压瓷技术在个性化瓷种植基台中的适应证与修复方法。方法 将专用瓷块通过热压在通用可铸金属基台(UCLA基台)上为30例种植患者行38颗个性化瓷基台修复,观察时间1个月～3年。结果 38颗个性化瓷基台修复体在观察期内无一例破损,牙龈健康,有2例上部全瓷冠破裂经重新修复后均取得满意的临床效果。结论 热压瓷技术制作个性化瓷种植基台修复技术可行,临床可获得更好的美学效果。?     

Antimicrobial profile of a dental implant abutment coating to prevent adhesion and migration of bacteria and screw loosening

ObjectiveFailure of dental implants treatment is frequently the result of bacterial colonization of implants followed by diseases like peri-implantitis. Recent studies have been made regarding the surface treatment of implants components, namely abutments that are in the interface of the living tissue with the implant. This work aimed at evaluating the antimicrobial profile of a silane-based coating with TiO₂ adapted to an abutment screw, that was also developed as an anti-loosening agent, to prevent adhesion and migration of Gram + and Gram-bacteria, Staphylococcus aureus, and Escherichia coli, respectively.MethodsDirect contact antimicrobial studies were conducted on coated and uncoated samples by resazurin fluorescent assay and cytotoxicity assessment was done via MTT indirect method on days 1 and 4. Sterilizations studies by FTIR analysis were also performed to understand the ideal balance between sterilization efficacy and coating functionality subjecting the samples to ethylene oxide, gamma irradiation, and autoclave sterilization, before antimicrobial testing. The implant system as a whole was also studied for its ability to block bacterial migration and preventing microleakage as well as an assessment of initial bacterial adhesion evaluated by scanning electron microscopy.ResultsDirect contact studies performed on coated samples showed a very high antimicrobial activity, while cytotoxicity assays revealed the coating to be safe and non-leachable. Sterilizations studies showed that the antimicrobial features of the coating were preserved and interchangeable regardless of the sterilization method. The implant system migration studies demonstrated that the implant system works as an efficient barrier for the studied bacteria.SignificanceThe acquired results clearly show that it is possible to obtain a highly functional coating with obvious and marked antimicrobial features that together with an abutment that prevents bacterial migration and versatility in sterilization methodology has a very high potential in the dental implant field.     

氧化锆瓷基台与钛种植体联合应用中不同连接体设计的有限元分析

目的：分析不同氧化锆基台对基台自身及钛种植体周围骨组织应力的影响,为氧化锆基台设计提供理论依据。方法：采用计算机辅助设计建立5种不同设计的氧化锆基台模型,并根据不同的基台模型设计了与之对应的种植体、牙槽骨及全瓷冠模型。用三维有限元方法对每个模型进行100N的斜向加载,分析不同氧化锆基台的设计对基台自身及牙槽骨应力分布及应力峰值的影响。结果：5种设计的等效应力的分布基本一致,基台的应力主集中在基台颈部连接体上方,皮质骨及松质骨的应力主集中于骨与种植体连接的最上方。5种设计等效应力的峰值不同,圆形连接体设计时氧化锆基台,皮质骨及松质骨的等效应力峰值均小于其他各设计组。结论：圆形连接体设计是本研究5种设计中氧化锆基台与钛种植体相连的最佳设计形式。     

侧方螺丝固位在粘结基台种植修复中的应用

目的:针对旋入式基台种植修复中的基台短小、固位不佳等问题,采用侧向螺丝进行固位种植修复咬距离不足患者的牙列缺损。方法:12例后牙缺失、咬距离不足(3～5)mm患者,其中,男4例,女8例,均采用侧方螺丝固位,1年后评价修复效果。结果:12例患者均成功修复,获得了满意的临床效果。结论:侧方螺丝固位较之其它方法可操作性好,固位良好,损伤小、治疗周期短,不失为一新的尝试。     

Effect of Casting Procedures on Screw Loosening in UCLA-Type Abutments

BACKGROUND: Screw loosening of implant restorations continues to be a complication in implant prosthodontics. Screw joints are subjected to a loss of initially applied torque because of friction and component misfit. It has been suggested that the loss of applied torque is less in machined metal abutments than in cast plastic abutments. PURPOSE: This study compared the loss of applied torque (detorque) values in machined titanium and in cast UCLA-type abutments for external hex abutment/implant interface. MATERIALS AND METHODS: Four groups of 12 samples each were evaluated: (1) machined titanium abutments, (2) premachined palladium abutments cast with palladium, (3) plastic abutments cast with nickel-chromium, and (4) plastic abutments cast with cobalt-chromium. Each abutment was torqued to 30 Ncm according to the manufacturer's instructions and detorqued three times. The mean loss of applied torque (detorque) was recorded as a percentage of the torque applied. Group means were calculated and compared using ANOVA and Tukey's LSD test. RESULTS: Mean detorque values were (1) 92.3 +/- 2.9%, (2) 81.6 +/- 5.0%, (3) 86.4 +/- 4.6%, and (4) 84.0 +/- 7.0%. Machined abutments demonstrated significantly greater detorque values compared with all cast groups (p < 0.05). No significant differences were found among cast groups. CONCLUSION: Machined abutments retained a significantly greater percentage of torque compared with cast abutments. Casting procedures decrease the percentage of applied torque, which may influence final screw joint stability.     

On the influence of superstructure connection on implant preload: A methodological and clinical study

In a combined in vitro and in vivo study strain gauges were used to register the deformation in two terminal implant abutment cylinders, when connecting three different prosthetic appliances. The prosthetic constructions were placed on the abutments and fastened both in vitro and in vivo by using different torque sequences. Furthermore, in the in vitro situation the three medial abutments were replaced by abutments which were 100 μm shorter.
The results show that even if the prosthetic constructions were judged to have a good clinical fit, relatively large External Preloads were registered both in vitro and in vivo . No significant differences in axial force or in bending moment were found between the torque sequences in vivo . There were, however, significant differences in axial force as well as in bending moment in the in vitro experiment. When the shorter medial abutments were used in vitro, a change in the axial force of approximately 200N was registered. The results confirm that the methodological approach used in this study is valid when evaluating preloads.     

Influence of implant abutment angulations on the fracture resistance of overlaying CAM-milled zirconia single crowns

Background: An in vitro study was performed to assess the effect of three implant abutment angulations and three core thicknesses on the fracture resistance of overlaying computer‐aided manufacturing (CAM) milled zirconia (Cercon^® system) single crowns. Methods: Three groups, coded A to C, with different implant abutment angulations (group A/0°, group B/15° and group C/30° angulation) were used to construct 15 crowns for each angulation. Forty‐five overlay restorations were milled using the Cercon^® system with zirconium core thicknesses of 0.4, 0.6 and 0.8 mm using five crowns for each angulation. The final restorations were prepared and stored in distilled water at mouth temperature (37 °C) for 24 hours prior to testing. The restorations were cemented using Temp Bond^®. The load required to break each crown and the mode of failure were recorded. All the results obtained were statistically analysed by the ANOVA test (level of significance p < 0.05). Tested crowns were examined using a stereomicroscope at 40X and selected crowns (five randomly selected from each group were further examined by scanning electron microscopy) to reveal the zirconia–ceramic interface and to determine the fracture origin. Results: Implant abutment angulations significantly (p < 0.05) reduced the fracture resistance of overlaying CAM‐milled zirconia single crowns. The fracture loads of Cercon^® crowns cemented onto abutment preparations with a 30° angulation were the lowest of the groups tested. The core thickness (0.4 to 0.8 mm) did not significantly (p > 0.05) affect the fracture resistance of the CAM‐milled zirconia single crowns. SEM showed that the origin of the fracture appeared to be located at the occlusal surfaces of the crowns and the crack propagation tended to radiate from the occlusal surface towards the gingival margin. Conclusions: The implant angulation of 30° significantly (p < 0.05) reduced the fracture resistance of overlaying CAM‐milled zirconia single crowns. Reducing the core thickness from 0.8 mm to 0.4 mm did not affect (p > 0.05) the fracture resistance of overlaying CAM‐milled zirconia single crowns.