二氧化锆全瓷冠修复的临床观察

目的:探讨临床使用二氧化锆全瓷冠修复的治疗效果。方法:选择55例患者共73颗牙,采用二氧化锆全瓷冠进行修复。之后随访观察,按照美国公共健康协会制定标准评估修复情况。结果:73颗二氧化锆全瓷冠的边缘完整性,牙龈状态,颜色等方面表现良好,有3例4个全瓷冠出现崩瓷。结论:二氧化锆全瓷冠临床上的修复效果良好,值得临床推广使用。     

Unusual explanation for the death of a car passenger

After collision of a car with the left rearside against a steel mast the 19-year-old front seat passenger was found comatose on the seat. CT imaging showed a depression fracture parietal on the left with an intracerebral haemorrhage on the opposite side. The cause of the injury was unknown to the surgeons at the time of operation. Despite neurosurgical intervention the patient died 24 h after the accident. The post-mortem showed an additional depression fracture at the base of the skull in the right temporal region arousing suspicion of an impalement injury. Only inspection of the car by the forensic pathologists revealed the gas pressure telescopic shock absorber to be the cause of the head injury. Received: 20 January 1997 / Received in revised form: 23 July 1997     

Telescopic suction tube for microsurgery

Summary An adjustable telescopic suction tube has been developed for microsurgery. Owing to this innovation, the surgeon can easily set the suction tube to a suitable length by gently pulling the end of the telescopic tube out or in.     

A 5-year evaluation of semipermanent composite resin crowns

ABSTRACT – The use of composite resin crowns in the restoration of traumatized and hypoplastic permanent incisors has proved to be of great clinical and aesthetic value for the pedodontic practice. Due to the composite resin materials and the acid etch technique, an easy method of making and retaining the restorations is at hand. The present study deals with long-term observations of composite resin crowns in restoring Ellis Class II and Class III coronal fractures of traumatized permanent incisors. In all, 253 composite resin crowns were controlled every year for a minimum of 5 years. In no case was an intermediate resin layer applied on etched enamel before the restoration material was placed. Surface, marginal and "body" discoloration, marginal leakage, marginal caries, abrasion, and fractures were controlled. The study demonstrated that discoloration of the surface of the restorations, and a discoloration of the restorative material not restricted to its surface ("body" discoloration) were the most frequent causes for considering the crowns as semipermanent restorations. The other factors seemed to be of minor clinical significance.     

全瓷冠用于前牙美容修复的临床效果体会

目的:探讨全瓷冠修复在牙列美容的应用效果。方法:随访观察和检查50件全瓷冠的颜色、颈部黑线、牙龈炎性反应、崩瓷情况。结果:全瓷冠颜色逼真,边缘密合,没有颈部变色和牙龈炎性反应,崩瓷也较少。结论:全瓷冠的前牙美容修复具有满意的临床应用效果,是值得推广的牙科修复材料。     

Reliability testing of indirect composites as single implant restorations

Purpose: To investigate the reliability and failure modes of indirect composites as single‐unit implant crowns. Materials and Methods: Thirty‐eight custom‐milled titanium alloy locking‐taper abutments were divided into two groups (n = 19 each), and crown build‐up of a mandibular molar was accomplished using two indirect composite systems (Ceramage, Shofu, Kyoto, Japan; Diamond Crown, DRM, Branford, CT). Three crowns of each material were loaded until failure for determination of the step‐stress profiles. Reliability testing started at a load 30% of the mean load to failure and used three profiles with increasing fatigue loading (step stress). Weibull curves with 300 N stress and 90% confidence intervals were calculated and plotted using a power‐law relationship. Weibull modulus “Beta” and characteristic strength “Eta” were identified, and a contour plot was used (Beta vs. Eta) for examining differences between groups. Specimens were inspected in polarized light and scanning electron microscope for fracture analysis. Results: Use level Weibull probability showed fatigue being a damage factor only for the Ceramage group (β= 3.39) but not for the Diamond Crown group (β= 0.40). Overlap in the confidence bounds resulted in no statistical difference. Irrespective of composite system, fracture initiated in the region immediately below the contact between the indenter and the cusp, with the crack propagating toward the margins of cohesive failure. Conclusions: No significant differences were observed in life and Weibull probability calculations for Ceramage and Diamond Crown veneered onto Ti alloy abutments. Failure modes comprised composite veneer chippings.     

Zirconia-implant-supported all-ceramic crowns withstand long-term load: a pilot investigation

OBJECTIVES: The purpose of this pilot investigation was to test whether zirconia implants restored with different all-ceramic crowns would fulfill the biomechanical requirements for clinical use. Therefore, all-ceramic Empress-1 and Procera crowns were cemented on zirconia implants and exposed to the artificial mouth. Afterwards, the fracture strength of the all-ceramic implant-crown systems was evaluated. Conventional titanium implants restored with porcelain-fused-to-metal (PFM) crowns served as controls. MATERIAL AND METHODS: Sixteen titanium implants with 16 PFM crowns and 32 zirconia implants with 16 Empress-1 crowns and 16 Procera crowns each--i.e., three implant-crown groups--were used in this investigation. The titanium implants were fabricated using the ReImplant system and the zirconia implants using the Celay system. The upper left central incisor served as a model for the fabrication of the implants and the crowns. Eight samples of each group were submitted to a long-term load test in the artificial mouth (1.2 million chewing cycles). Subsequently, a fracture strength test was performed with seven of the eight crowns. The remaining eight samples of each group were not submitted to the long-term load in the artificial mouth but were fracture-tested immediately. One loaded and one unloaded sample of each group were evaluated regarding the marginal fit of the crowns. RESULTS: All test samples survived the exposure to the artificial mouth. Three Empress-1 crowns showed cracks in the area of the loading steatite ball. The values for the fracture load in the titanium implant-PFM crown group without artificial loading ranged between 420 and 610 N (mean: 531.4 N), between 460 and 570 N (mean: 512.9 N) in the Empress-1 crown group, and in the Procera crown group the values were between 475 and 700 N (mean: 575.7 N) when not loaded artificially. The results when the specimens were loaded artificially with 1.2 million cycles were as follows: the titanium implant-PFM crowns fractured between 440 and 950 N (mean: 668.6 N), the Empress-1 crowns between 290 and 550 N (mean: 410.7 N), and the Procera crowns between 450 and 725 N (mean: 555.5 N). No statistically significant differences could be found among the groups without artificial load. The fracture values for the PFM and the Procera crowns after artificial loading were statistically significantly higher than that for the loaded Empress-1 crowns. There was no significant difference between the PFM crown group and the Procera group. CONCLUSIONS: Within the limits of this pilot investigation, it seems that zirconia implants restored with the Procera crowns possibly fulfill the biomechanical requirements for anterior teeth. However, further investigations with larger sample sizes have to confirm these preliminary results. As three Empress-1 crowns showed crack development in the loading area of the steatite balls in the artificial mouth, their clinical use on zirconia implants has to be questioned.     

Fracture strength of two oxide ceramic crown systems after cyclic pre-loading and thermocycling

The aim of the present study was to investigate the fracture resistance of zirconia crowns and to compare the results with crowns made of a material with known clinical performance (alumina) in away that reflects clinical aspects. Sixty crowns were made, 30 identical crowns of alumina and 30 of zirconia. Each group of 30 was randomly divided into three groups of 10 crowns that were to undergo different treatments: (i) water storage only, (ii) pre-loading (10 000 cycles, 30-300 N, 1 Hz), (iii) thermocycling (5-55 degrees , 5000 cycles) + pre-loading (10 000 cycles, 30-300 N, 1 Hz). Subsequently, all 60 crowns were subjected to load until fracture occurred. There were two types of fracture: total fracture and partial fracture. Fracture strengths (N) were: group 1, alumina 905/zirconia 975 (P = 0.38); group 2, alumina 904/zirconia 1108 (P < 0.007) and group 3, alumina 917/zirconia 910 (P > 0.05). Total fractures were more frequent in the alumina group (P < 0.01). Within the limitations of this in vitro study, it can be concluded that there is no difference in fracture strength between crowns made with zirconia cores compared with those made of alumina if they are subjected to load without any cyclic pre-load or thermocycling. There is, however, a significant difference (P = 0.01) in the fracture mode, suggesting that the zirconia core is stronger than the alumina core. Crowns made with zirconia cores have significantly higher fracture strengths after pre-loading.     

铸造金属桩核烤瓷冠修复残根残冠的临床观察

目的探讨铸造金属桩核修复残根残冠的方法和疗效,以及对保留残根残冠的临床意义。方法 2002年1月至2010年12月间应用铸造金属桩核结合烤瓷全冠的修复方法治疗927例1 143颗牙。观察2年后修复效果,按评价标准分为修复优良和修复失败。在修复失败类中又以有无桩脱落、牙折和根尖炎症状再分为可逆和不可逆性。结果 927例1143颗牙均得到了2年以上的随访观察,修复优良占88.45%（1011/1143）,修复失败中不可逆性占22.72%（30/132）。结论铸造金属桩核修复残根残冠是目前临床上利用现有牙根最大限度地提高修复效果的有效途径,已成为临床保存性修复的重要内容。