The adaptation of implant-supported superstructures to the alveolar crest: a follow-up of 49 cases

A prospective clinical and radiographic study has been carried out in 49 patients with a total of 252 implants. In a mixture of 17 edentulous mandibles, 20 edentulous maxillas, nine partial edentulous cases, and three single-tooth cases, prosthetic treatments were aimed at getting as close an adaptation as possible between gingival tissues and superstructure. The shortest possible abutments were used, and the implants were surgically positioned subcrestally. The results during a 5-year follow-up showed a success rate of 98.9% for fixtures in the lower jaw and 96.3% for the upper jaw with a total success rate of 97.3%. The marginal bone reduction during five years with closely adapted superstructures was 0.11 mm in the mandible and 1.1 mm in the maxilla. Our results support the use of close gingivally adapted superstructures, although oral hygiene controls and instructions are regularly advisable.     

Evaluation of a new method to achieve optimal passivity of implant-supported superstructures.

Statement of problem. Passive fit of implant-supported superstructures has been suggested as a prerequisite for maintenance of osseo-integration and for successful prosthetic reconstruction. PURPOSE: This study evaluated the degree of fit of superstructures cemented onto titanium abutments, compared to structures cast onto gold cylinders. MATERIAL AND METHODS: An impression was taken and a master cast made of five implants mounted in a stainless steel model. Six similar porcelain fused to metal superstructures with standardised dimensions were then fabricated. One group featured castings onto gold UCLA abutments, while in the other group the structures were cemented onto tapering titanium abutments. Vertical discrepancies between implants and both types of superstructures were measured on at six locations around each implant using a reflex microscope. Measurements were taken after securing the structures to the model with a single screw (torqued to 32 Ncm) placed in various locations and also after tightening all the retaining screws simultaneously to 10 Ncm. RESULTS: With the new single-screw procedure, no significant difference in mean gap size was noted between the two groups. The discrepancies were significantly larger for certain screw locations (1 and 5), indicating that the one-screw test might be an inaccurate way of assessing fit. After tightening all the retaining screws simultaneously to 10 Ncm, the mean gaps were 11.9 microns for the cemented group and 17.8 microns for the cast group. CONCLUSION: Although not statistically significant, cementing of superstructures onto titanium abutments improved the fit up to 50% compared to casting the structures onto gold UCLA-abutments. Tightening one terminal abutment screw and evaluating the discrepancies at the other abutments (one-screw test) distorted the results when evaluating the fit of long-span, implant-supported ceramo-metal superstructures. CLINICAL IMPLICATIONS: The results of this study indicate that cementing superstructures onto titanium abutments will lead to an improved degree of fit, compared to casting superstructures onto gold cylinders. In addition, the one-screw test may not be an accurate method of determining the level of passivity of long-span, ceramo-metal, implant-supported superstructures.     

Improving the fit of implant-supported superstructures using the spark erosion technique

PURPOSE: The purpose of this study was to determine whether the passive fit of the implant-retained single-cast framework could be improved by spark erosion treatment. MATERIALS AND METHODS: An initial cast was produced in a transparent resin material. Five Branemark System implants were arranged in the interforaminal region, and abutments were placed on them with a torque of 20 Ncm. An impression was made using a standard impression technique described by Branemark. A corresponding master cast suitable for the spark erosion post-framework fabrication was produced. From this master cast, 12 frameworks were produced in a conventional single-cast procedure. Six of these were made of a high-gold alloy (Stabilor G); the other 6 were made of pure titanium (Biotan). These frameworks were then refined using the SAE Secotec Spark Erosion System. To measure the accuracy of the framework fit, the frameworks were measured before and after the spark erosion treatment using 2 different measurement methods-scanning electron microscopy to measure the gap widths (Sheffield test) and photoelastic stress analysis. RESULTS: The results of both measurement techniques correlated and demonstrated significant improvement in the accuracy of fit or in the passive fit for all 12 frameworks after spark erosion treatment. This improvement was statistically significant for the titanium frameworks. DISCUSSION: Dental practitioners and technicians should strive to achieve a precise passive fit of frameworks and superstructures to minimize additional stress at the interfaces of the prosthesis, abutment, and implant. CONCLUSION: The clinical use of the spark erosion technique to refine framework fit is recommended. (More than 50 references.)     

A clinical evaluation of 76 implant-supported superstructures in the composite grafted maxilla

The aim of the study was to evaluate the material behaviour and nature of implant-supported superstructures in function. A total of 37 overdentures, 26 fixed partial and 13 fixed full dentures with a mean lifetime of 40 months were clinically evaluated in relation to damage, occlusion and articulation, parafunction, retentive devices, hygiene and speech problems. In general 70% of all superstructures were damaged. Fixed partial dentures were significantly less damaged than overdentures and fixed full dentures (P<0.001). A significant high percentage of newly gained parafunction was found (P<0.05).     

Evaluation of the marginal precision of one-piece complete arch titanium frameworks fabricated using five different methods for implant-supported restorations

Objective: The aim of the present work was to compare the marginal precision of titanium frameworks for a complete arch‐fixed prosthesis fabricated using five different methods. Methods: A prospective study was designed. Fifteen titanium frameworks for totally edentulous upper or lower jaws, each supported by five to nine implants, were assigned to five study groups, so as to have three frameworks in each group for each technique: (1) lost wax technique frameworks, (2) cast titanium sovrastructures laser welded to prefabricated titanium copings, (3) Procera ^® Implant Bridge, (4) Cresco Ti System^? and (5) CAM StructSURE^® Precision Milled Bar. The microgap between the framework and the shoulders of implant analogues was measured on the master cast with a stereomicroscope at a magnification of 100 × at four different locations, yielding a total of 364 data points on 91 implants. Data were analyzed using an ANOVA and a Tukey post hoc test (P=<0.05). Results: The mean values for the microgap were 78 μm (SD±48) for lost wax technique frameworks, 33 μm (SD±19) for cast titanium sovrastructures laser welded to titanium copyings, 21 μm (SD±10) for the Procera ^® implant bridge, 18 μm (SD±8) for the Cresco Ti System^? and 27 μm (SD±15) for the CAM StructSURE^®. The differences among the mean values were statistically significant (P<0.01 or P<0.05). The comparisons among groups 3, 4, and 5 and between groups 2 and 5 were not significant (P>0.05). Conclusion: The computer‐aided procedures analyzed in the present study were able to produce a precision‐fitting framework, with no significant differences among them and, at the same time, showed a greater precision compared with the traditional casting methods or with the use of prefabricated titanium copings. However, it should be noted that, even if group 2 frameworks were not as accurate as groups 3 and 4, cast titanium sovrastructures laser welded to prefabricated titanium copings showed significantly better marginal precision than the frameworks produced with the lost wax technique.     

Impression techniques and misfit-induced strains on implant-supported superstructures: an in vitro study

The purpose of this study was to compare misfit-induced strains on implant-supported superstructures fabricated by two impression techniques and two different elastomeric impression materials. A master cast hosting four Straumann implants was constructed. On this cast, a total of 21 implant-level impressions were made by the direct technique using a polyether impression material and synOcta screwed aluminum impression caps (PE-D), and by the indirect technique using polyether (PE-IN) or polyvinylsiloxane impression material (VPS-IN) with snap-on impression caps and synOcta plastic positioning cylinders. Two casts were randomly selected from each group of seven, and a total of four screw-retained superstructures, supported by either two or four implants (one of each type on both casts), were cast in a gold alloy for each group. Linear strain gauges were bonded on the superstructures, and misfit-induced strains were recorded during superstructure connection on each of the working casts and on the master cast using a data acquisition system and corresponding software at a sample rate of 10 kHz. Connection on the implants in the master cast increased strains considerably on most of the superstructures, in comparison with strain gradients measured when the superstructures were connected on the casts from which they were fabricated (P <.05). The differences in strain amplitude between connection on the cast from which the superstructure was fabricated and on the master cast were higher for superstructures fabricated by PE-D than for those fabricated by PE-IN and VPS-IN. The snap-on indirect impression technique for Straumann implants leads to acceptable superstructures, regardless of the impression material used.     

镍铬钛烤瓷金瓷剪切结合强度的测试

目的通过对自制镍铬钛（Ni-Cr-Ti）烤瓷合金与Vita常用瓷的剪切结合强度的测试,探讨镍铬烤瓷合金添加钛、混合稀土金属以及不含铍（Be）对金瓷结合性能的影响。方法使用中国科学院金属研究所研制的镍铬钛烤瓷合金,共分3个试验组,各组成分略有差异,以HI BOND非贵金属烤瓷合金为对照组,所有试件在万能试验机上采用剪切力试验测试金瓷分离时的载荷。结果3个实验组剪切强度值依次为R1组（28.1864±2.80702）MPa,R2组（26.1585±3.38148）MPa,R3组（25.1663±3.12508）MPa,对照组为（29.1436±3.28302）MPa。通过单向方差分析和SNK检验,各组之间差异均无显著性意义（P〉0.05）。结论自制镍铬钛烤瓷合金的金瓷结合良好,剪切结合强度可以达到临床应用的要求。     

两种上部结构设计在前牙区种植修复的临床效果研究

目的:比较两种不同的上部结构设计在上颌前牙区单颗牙种植修复中的临床效果。方法:选择连续于我科就诊的57例上颌前牙区单颗牙种植修复患者,按照种植体长轴分为两组,A组26例长轴位于牙冠切端舌侧至舌隆突之间,上部结构设计为低边缘钛基台和舌侧开孔的氧化锆全瓷冠,戴牙前于体外预先粘结;B组31例长轴位于牙冠切端或唇侧,设计为个性化氧化锆基台和氧化锆全瓷冠,于口内常规粘结。戴牙当天和修复后12个月复诊时记录红色美学指数(pink esthetic score,PES),并于12个月复诊时检测种植体周围边缘骨吸收量(marginal bone loss,MBL)、改良菌斑指数(modified plaque index,mPI)、改良出血指数(modified sulcus bleeding index,mSBI)及各种机械并发症。结果:戴牙当天和复诊时两组PES差异均无统计学意义;修复后12个月,两组PES值均高于戴牙当天(P<0.05);两组MBL、mPI、mSBI值差异均无统计学意义。A组未发生机械并发症;B组出现2例钛基台与氧化锆穿龈结构之间松脱。结论:两种上部结构设计在上颌前牙区单颗牙种植修复中均能取得良好的效果,临床上可以根据病例具体情况选择。     

Improvement and long-term stability of neuromuscular adaptation in implant-supported overdentures

Objectives: In edentulous patients, implant-supported overdentures can improve chewing efficiency and patient satisfaction, and even a positive impact on bone tissue preservation has been observed. The objective of this long-term study was to investigate whether kinesiographic and electromyographic (EMG) parameters would also benefit from implant placement and whether the status achieved would remain consistent over time.
Material and methods: The functional adaptability of the neuromuscular system in edentulous patients has been recorded in four different states of restoration: (1) insufficient old dentures, (2) new complete dentures, (3) implant-supported overdentures, and (4) implant-supported overdentures 10 years in use. In each state of restoration, the neuromuscular adaptation was assessed during masticatory activity on the basis of myodynamic parameters such as vertical opening, frontal extension and closing velocity. EMG parameters, i.e. Musculus masseter and Musculus temporalis activities were recorded simultaneously.
Results: The results revealed a general increase in the myodynamic and EMG-parameters. All of them clearly approached the values for normal dentate subjects and maintained this level over a period of 10 years. The significant changes between states 2 and 3 indicate that implant stabilization of dentures is accompanied by an immediate increase of the neuromuscular parameters.
Conclusions: In elderly edentulous patients, the treatment with two interforaminal implants provides evidence of neuromuscular adaptation towards values of healthy dentate. Thus, the known benefits of implant placement such as tissue perseverance and improved function are complemented by improved neuromuscular adaptation.     

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目的 对比钯银(Pd-Ag)合金和钴铬(Co-Cr)合金的机械性能及金瓷结合强度,为临床提供基础数据.方法 本研究于2010年12月至2011年2月在中国科学院金属研究所分析测试部完成.常规方法制作Pd-Ag合金和Co-Cr合金试件,首先对二者进行硬度测试和拉伸测试,然后分别行常规烤瓷并利用水平剪切法进行界面结合强度测试,利用扫描电镜(SEM)和能谱分析技术对金瓷界面进行观察和元素分析.结果 硬度:Pd-Ag合金为(187.44±3.64) HV,低于Co-Cr合金(361.53±10.15)HV(P＜ 0.05).拉伸测试:Pd-Ag合金的屈服强度为(467.50±14.40)MPa,小于Co-Cr合金(568.10± 30.94) MPa (P＜ 0.05);Pd-Ag合金的抗拉强度为(631.83±15.51)MPa,小于Co-Cr合金(758.73±25.85) MPa(P＜ 0.05).剪切强度:Pd-Ag合金为(57.67±5.44) MPa,Co-Cr合金为(26.80±4.95)MPa,差异有统计学意义(P＜0.05).扫描电镜观察和能谱分析显示:2种合金与瓷之间均存在过渡层,合金与瓷层间存在元素的相互渗透.结论Pd-Ag合金的机械性能低于Co-Cr合金,但可满足临床需要;而Pd-Ag合金的金瓷结合强度高于Co-Cr合金.     

再利用镍铬钛烤瓷合金的铸流性及元素分析

目的:探讨再利用镍铬钛烤瓷合金的表面处理方法及回收料含量对铸流性的影响,观察铸件金相结构并分析其元素构成。方法:在回收料含量一定条件下,比较不同表面处理方法对铸流率的影响;在同一表面处理方法条件下,比较不同回收料含量对铸流率的影响。观察分析铸件金相结构及表面元素构成比。结果:经喷砂或Inconel合金酸洗液酸洗的再利用合金铸流率较高;再利用合金中回收料含量应控制在62.5%或以下;再利用合金铸件金相结构及表面元素构成比与新合金铸件基本相似。结论:经过适当处理的再利用镍铬钛烤瓷合金具有较好的铸流性,所得铸件金相结构及元素构成改变不大。     

除气和预氧化对含钛镍铬合金金瓷结合强度的影响

目的研究上瓷前含钛镍铬合金除气和预氧化对其金瓷结合强度的影响。方法三点弯曲法测定A组（除气）、B组（预氧化）和C组（无热处理）试件的金瓷结合强度,扫描电镜和X线衍射分析金瓷界面。结果 A组金瓷结合强度为（39.812±2.466）MPa,B组为（37.406±5.238）MPa,C组为（32.704±3.140）MPa。A组与B组间差异无统计学意义（P〉0.05）,但2组均明显大于C组,且差异有统计学意义（P〈0.05）。扫描电镜下,3组均可见金属与瓷之间有一清晰的过渡层,A组和B组界面过渡层厚度约10～15μm,金瓷结合良好,无明显的中间层、气泡等缺陷。C组过渡层厚度约5～10μm,见明显孔洞和裂纹。X线衍射分析,3组金瓷界面过渡层局部出现Sn、Ti、Si的聚集,Ti元素呈不规则扩散曲线。结论除气而无需再预氧化也能获得较高的金瓷结合强度,预氧化能提高金瓷结合强度,无热处理试件金瓷结合强度较低。     

The effect of commercially pure titanium and alternative dental alloys on the marginal fit of one-piece cast implant frameworks

OBJECTIVES: The purpose of this study was to measure and compare the passive fit and vertical fit of one-piece cast frameworks fabricated with three different materials: commercially pure titanium (CP Ti), cobalt-chromium alloy (Co-Cr) and nickel-chromium-titanium alloy (Ni-Cr-Ti). METHODS: Fifteen frameworks simulating bars for fixed prosthesis in a model with five implants were fabricated and arranged into three different groups according to the material used. The fit of the framework abutment interface was measured using an optical microscope, when only one screw was manually tightened at a terminal abutment (passive fit) or when all framework screws were tightened to 10 N cm torque (vertical fit). Data were statistically analyzed using Kruskal-Wallis and Mann-Whitney tests (alpha=0.05). RESULTS: Mean and standard deviation values of passive fit and vertical fit are presented, respectively: CP Ti [88 (74) microm and 22 (9) microm], Co-Cr [229 (184) microm and 66 (35) microm], Ni-Cr-Ti [200 (175) microm and 32 (24) microm]. There were no significant differences between passive fit of Co-Cr and Ni-Cr-Ti frameworks (p=0.313), but both alloys were statistically different from CP Ti (p<0.001 and 0.035, respectively), which showed the best results. As for vertical fit, CP Ti and Ni-Cr-Ti alloy were statistically similar (p=0.162) and they presented a better vertical fit than Co-Cr alloy (p<0.001). CONCLUSIONS: Within the limitations of this study, it was possible to conclude that one-piece cast frameworks resulted in unacceptable passive fit and vertical fit, no matter which material had been used to fabricate them. However, the best results were obtained using CP Ti followed by Ni-Cr-Ti and Co-Cr alloys, respectively.     

镍铬和含钛镍铬烤瓷合金的耐腐蚀性能研究

目的 评价2种镍铬和1种含钛镍铬烤瓷合金试件在人工唾液中的耐腐蚀性能.方法 采用电化学极化曲线法测定2种镍铬和1种含钛镍铬烤瓷合金试件的自腐蚀电流密度(Icorr)、极化电阻(Rp)、自腐蚀电位(Ecorr),并得出3种合金的极化曲线.应用场发射扫描电子显微镜(FSEM)观察实验前后试件表面形貌变化,并对数据进行单因素方差分析.结果 Bellabond镍铬烤瓷合金的Icorr低于Neotitan含钛镍铬烤瓷合金(P<0.05)及粤海镍铬烤瓷合金(P>0.05):粤海镍铬烤瓷合金Icorr低于Neotitan含钛镍铬烤瓷合金(P>0.05).Bellabond镍铬烤瓷合金的Rp明显高于粤海镍铬烤瓷合金(P<0.05)及Neotitan含钛镍铬烤瓷合金(P<0.05);粤海镍铬烤瓷合金试件的Rp高于Neotitan含钛镍铬烤瓷合金(P>0.05).Bellabond镍铬烤瓷合金的Ecorr低于粤海镍铬烤瓷合金(P>0.05)及Neotitan含钛镍铬烤瓷合金(P>0.05):Neotitan含钛镍铬烤瓷合金的Ecorr高于粤海镍铬烤瓷合金(P>0.05).FSEM显示,Bellabond镍铬烤瓷合金表面腐蚀较粤海镍铬烤瓷合金和Neotitan含钛镍铬烤瓷合金轻微.结论 Bellabond镍铬烤瓷合金的耐腐蚀性较粤海镍铬烤瓷合金和Neotitan含钛镍铬烤瓷合金优良,Neotitan含钛镍铬烤瓷合金耐腐蚀性与粤海镍铬烤瓷合金无明显差异.     

Six-year clinical outcomes of implant-supported acrylic vs. ceramic superstructures according to the All-on-4 treatment concept for the rehabilitation of the edentulous maxilla

Odontology - The aim of the current study was to document the long-term clinical results of the use of two prosthetic techniques for the rehabilitation of completely edentulous maxillae according...     

Evaluation of speech in patients rehabilitated with various oral implant-supported prostheses

In the present study, speech function was assessed in edentulous patients wearing fixed or removable dental prostheses supported or not by oral implants. A total of 138 patients participated in the present research. The experimental group (n=113) was divided in 4 subgroups. Subgroup FD/FFPi comprised 22 patients with a maxillary full denture (=FD) and a mandibular fixed full prosthesis on implants (=FFPi). Subgroup FFPi/ND consisted of 27 patients with a maxillary fixed full prosthesis on implants and a natural dentition (=ND) in the mandible. Subgroup FD/ODi included 49 patients wearing a maxillary full denture and a mandibular overdenture on 2 implants (=ODi). Subgroup FFPi/FFPi comprised 15 patients having a fixed full prosthesis on implants in both jaws. The outcome of the logopedic screening of the experimental group was compared with that of a control group of subjects having a natural dentition (ND/ND; n=25). A standard clinical procedure for evaluation of speech was carried out by a speech pathologist. Besides, specific oral and prosthetic parameters were scored in all patients. It was established that one or more pronunciation difficulties occurred in 84% of the patients of the experimental group. This was significantly more than in the control group, where half the number of subjects had some speech deficiencies. No clear influence of specific oral and prosthetic parameters could be identified. From the present results, it could be concluded that in patients rehabilitated with oral implant-supported prostheses speech disorder is more frequently observed than in subjects with a natural dentition.     

老年下颌牙列缺失患者种植覆盖义齿治疗的临床评估

无牙颌是一常见的口腔疾病,全球社会人口老化的发展趋势导致牙列缺失患者的人数相继增加。近年来,随着种植技术越发成熟,以种植义齿为导向的修复方式在提高患者的生活质量和改善心理素质方面均获得良好反响。下颌无牙颌种植覆盖义齿主要具有两大优势：相较于传统单颌全口义齿,具有更优良的固位和咀嚼效能;相较于种植固定义齿,所需的植入位点更少,且能恢复更多缺损的软组织,从而有助于恢复美观和发音,价格也更为患者所接受。因此,本文通过系统性的整理、分析和探讨下颌种植覆盖义齿针对老年牙列缺失患者的临床疗效,结合现有相关研究中对于下颌种植覆盖义齿操作过程中种植体数目、植入位点及上部修复体的选择要点,进一步阐释其在下颌无牙颌修复中的优势。     

老年下颌牙列缺失患者种植覆盖义齿治疗的临床评估

无牙颌是一常见的口腔疾病,全球社会人口老化的发展趋势导致牙列缺失患者的人数相继增加。近年来,随着种植技术越发成熟,以种植义齿为导向的修复方式在提高患者的生活质量和改善心理素质方面均获得良好反响。下颌无牙颌种植覆盖义齿主要具有两大优势：相较于传统单颌全口义齿,具有更优良的固位和咀嚼效能;相较于种植固定义齿,所需的植入位点更少,且能恢复更多缺损的软组织,从而有助于恢复美观和发音,价格也更为患者所接受。因此,本文通过系统性的整理、分析和探讨下颌种植覆盖义齿针对老年牙列缺失患者的临床疗效,结合现有相关研究中对于下颌种植覆盖义齿操作过程中种植体数目、植入位点及上部修复体的选择要点,进一步阐释其在下颌无牙颌修复中的优势。