国产牙科X线机的评价

目的：评价国产牙科Ｘ线机的生产质量水平。方法：通过测定全口牙齿相对于皮肤吸收射线的剂量、牙科Ｘ线机头表面散漏射线量及照片分辩率,与国外同类产品比较。结果：国产牙科Ｘ线机在防护剂量方面明显优于国外同类产品,但在电器控制,外形工艺和机械灵活性等方面仍陈旧落后。结论：国产牙科Ｘ线机应进一步改进完善,更好地满足临床应用的需要。     

金属烤瓷修复体在口腔内的修理

金属烤瓷修复体已经并将是一种普及的齿科修复体.尽管在制作上及功能上有甚多的变化,但同时也存在着损坏的可能.这种损坏往往涉及到修复体的瓷质部分.现介绍一种简单而预后良好的修理技术,有助于延长这些修复体的使用寿命.这种修理包括对金属部分的制备及对瓷质特殊处理,瓷质的特殊处理包括使用氢氟酸作酸蚀剂及硅烷粘接剂.已用此技术修理的许多金属烤瓷修复体均得到良好的效果.     

口腔内金属修复物的成分分析

目的：测定口腔内金属修复物的成分，确定使用的合金种类，以使牙科金属过敏患者避免再次使用此种合金。方法：用细砂纸及圆锥形抛光磨头，采取微量口腔内金属修复物，通过EDXRF(荧光X线分析仪)测定所含金属成分，确定合金种类。结果：14例可疑牙科金属过敏患者中，牙科金属修复物120个，按照检出频度的高低．排在前10位的金属元素分别是Ag、Cu、Au、Pd、Zn、Sn、Co、Cr、In和Mo。Au-Ag-Pd合金的使用频度为65％，Ag-Sn-Hg合金为2.5％，Ag合金为5.4％，Au合金为14.6％，Ni-Cr、Co-Cr合金为10.1％，其他2.4％。2种以上异种合金共存同一口腔环境中的患者12例,5种合金同时存在者1例。含Hg的银汞合金的使用频度为2.5％，与10年前的使用频度16％相比下降明显。Ni、Cr、Co的使用频度未见明显改变。结论：被疑牙科金属过敏的患者中，异种金属同存的现象严重，提示在口腔科临床工作中，尽量避免使用异种金属及含Hg和Ni等易诱发过敏的金属合金。     

X线探伤技术及其在口腔修复中的应用

口腔修复体中的支架、卡环和冠桥等,虽然表面看上去毫无瑕疵,完全符合修复体的质量要求,但运用X线探伤技术却经常见到修复体内部存在着许多气孔、异物、杂质等缺陷,这往往导致患者戴用修复体一段时间后,修复体断裂,造成修复失败。本文将就X线探伤技术及其在口腔修复中的应用等进行综述。     

X线探伤技术及真在口腔修复中的应用

口腔修复体中的支架、卡环和冠桥等,虽然表面看上去毫无瑕疵,究全符合修复体的质量要求,但运用X线探伤技术却经常见到修复体内部存在着许多气孔、异物、杂质等缺陷,这往往导致患者戴用修复体一段时间后,修复体断裂,造咸修复失败.本文将就X线探伤技术及其在口腔修复中的应用等进行综述.     

X线探伤技术及其在口腔修复中的应用

口腔修复体中的支架、卡环和冠桥等，虽然表面看上去毫无瑕疵，完全符合修复体的质量要求，但运用X线探伤技术却经常见到修复体内部存在着许多气孔、异物、杂质等缺陷，这往往导致患者戴用修复体一段时间后，修复体断裂，造成修复失败。本文将就X线探伤技术及其在口腔修复中的应用等进行综述。     

常用牙科金属的研磨与抛光方法

铸造完成后的铸件都需进行表面处理,如喷砂、研磨、电解、抛光等,这些都已经成为修复技工的常规操作。铸件的后期表面处理可以得到光滑亮泽的表面,从而减少食物以及菌斑等的附着,减少对软组织的刺激,减少异物感,同时也可增加美感,更重要的是可以改善铸件的表面性状和适应性,提高铸件的抗磨损、抗腐蚀和抗应力疲劳等性能。本文就临床常用牙科金属的研磨与抛光展开讨论,介绍一些操作技巧和心得体会。     

X线探伤法检查牙科铸造体内部缺陷探讨

牙科铸造体的缺陷分内部缺陷、外部缺陷和铸造体变形三大类。其中外部缺陷和铸造体变形只需外部观察即可确认,但内部缺陷因不能直观而无法进行探伤,由于潜在缺陷使铸件强度降低,修复体使用寿命     

口腔数码X线成像系统临床应用

口腔数码Ｘ线成像系统 (ｏｒａｌｄｉｇｉｔａｌｉｍａｇｅｓｙｓｔｅｍ ,ＯＤＩＳ)具有成像速度快 ,传输图像文字迅速 ,便于储存查找等优点 ,受到口腔科临床医生和有关学者的关注。由于设备昂贵和技术人员须具备计算机知识和操作技能等原因 ,该系统自上世纪 80年代中期问世以来未能在口腔医学临床广泛应用 ,国内报道甚少。一年来佛山市口腔医院引进并使用口腔数码Ｘ线成像系统 (公安部第一研究所研制 ) ,取得良好的社会效益和经济效益。作者就该系统应用效果及体会总结报道如下。1　材料和方法口腔数码Ｘ线成像系统ＯＤＩＳ＿1型 ,含口腔数…     

金属烤瓷修复体在临床上的应用

金属烤瓷修复体是目前国际上流行的一种修复方法 ,是金属与瓷的复合体 ,具有金属的强度高、耐磨、不易老化和陶瓷材料的不导热、不导电、光学性能与釉质相近、色泽逼真的优点 .从 1995年～ 1998年 ,我们在临床中共做了 65 6件金属烤瓷修复体 ,取得了一些经验和体会 .现介绍如下 :1　临床病例资料 表 1、表 2 :表 1　　 338例 65 6件烤瓷修复统计表分　类项　目病例数牙数牙体缺损牙体缺损保护冠桩　　冠3 65 05 04 85 65 6牙面变色氟斑牙四环素牙死髓牙12183 23 65 83 8牙列缺失一般固定桥基牙长轴不一致 牙体倾斜固定桥 长桥修复 桥体…     

Adherence of investment to Au–Pd–Ag alloy using a vacuum–argon pressure casting machine

OBJECTIVE: The removal of adhered investment material from marginal metal surfaces represents a possible risk of poor marginal adaptation.The aim of this work was to evaluate the effects of argon on investment adherence to the casting surface and on the alloy surface microstructure. METHODS: A die of stainless steel was used. 10 wax copings were cast by vacuum-argon pressure, while 10 copings by vacuum-air pressure using a Combilabor CLG-77 A in a graphite crucible; supply was direct with curved sprues of slashed circle 3.5 mm. The alloy used was Herabond. After coarse investment, removal of all specimens were investigated with scanning electron microscopy and semi-quantitative digital densitometry. RESULTS: The specimens cast under vacuum-argon pressure showed less amount of investment adhered (unpaired t test of grouped specimens, difference 2.896x10(5)pixel; p=0.002) while the grain size on the casting surface increased significantly p=0.000 (difference 5.968(microm). SIGNIFICANCE: Vacuum-argon pressure supply during casting reduces the investment adherence to the metal surface, and increases the packing density and size of the grains, especially on the casting surface. These minimize the risk of marginal distortions due to casting cleaning procedures and facilitate the finishing and polishing procedures.     

Ti—75铸造后机械性能测试的研究

目的：研究及比较Ｔｉ－７５金属在牙科铸造后的机械性能。方法：利用Ｉｎｓｔｒｏｎ拉伸试验机，对Ｔｉ－７５金属牙科铸造后部分力学性能进行了测试研究，并与Ｔｉ－６Ａｌ－４Ｖ及临床常用钴铬合金进行了比较。结果：Ｔｉ－７５铸造后抗拉强度为８５６．７ＭＰａ，屈服强度为５４０ＭＰａ延伸率为７．３％。Ｔｉ－６Ａｌ－４Ｖ铸造后抗拉强度为９５６．７ＭＰａ，屈服强度为５９０ＭＰａ，延伸率为５．２％。Ｃｏ－Ｃｒ合金铸造后抗拉强度为６５１．２ＭＰａ，屈服强度为４７８．８ＭＰａ，延伸率为６．１％。结论：Ｔｉ－７５金属铸造后抗拉强度，屈服强度及延伸率等性能指标均优于钴铬合金，延伸率也高于Ｔｉ－６Ａｌ－４Ｖ合金。     

Cutting efficiency of air-turbine burs on cast titanium and dental casting alloys

OBJECTIVE: The purpose of this study was to investigate the cutting efficiency of air-turbine burs on cast free-machining titanium alloy (DT2F) and to compare the results with those for cast commercially pure (CP) Ti, Ti-6Al-4V alloy, and dental casting alloys. METHODS: The cast metal (DT2F, CP Ti, Ti-6Al-4V, Type IV gold alloy and Co-Cr alloy) specimens were cut with air-turbine burs (carbide burs and diamond points) at air pressures of 138 or 207 kPa and a cutting force of 0.784 N. The cutting efficiency of each bur was evaluated as volume loss calculated from the weight loss cut for 5 s and the density of each metal. The bulk microhardness was measured to correlate the machinability and the hardness of each metal. RESULTS: The amounts of DT2F cut with the carbide burs were significantly (p < 0.05) greater than for the other titanium specimens at either 138 or 207 kPa. The diamond points exhibited similar machining efficiency among all metals except for Type IV gold alloy. The increase in the volume loss of Co-Cr alloy (Vitallium) cut with the diamond points showed a negative value (-29%) with an increase in air pressure from 138 to 207 kPa. There was a negative correlation between the amounts of metal removed (volume loss) and the hardness (r2 = 0.689) when the carbide burs were used. SIGNIFICANCE: The results of this study indicated that a free-machining titanium alloy (DT2F) exhibited better machinability compared to CP Ti and Ti-6Al-4V alloy when using carbide fissure burs. When machining cast CP Ti and its alloys, carbide fissure burs possessed a greater machining efficiency than the diamond points and are recommended for titanium dental prostheses.     

不同铸造合金对铸造冠边缘适合性影响的实验研究

目的观察Dentaurum包埋材料与3种牙科合金匹配对铸造冠边缘适合性的影响。方法制作模拟后牙全冠外形的标准帽状试件及圆管,于试件上制作30个熔模,随机分为3组,每组按照Dentaurum包埋材料的使用说明进行有圈包埋,分别采用3种合金进行铸造。铸造冠在原标准帽状试件上试合,在扫描电镜下测量铸件的边缘浮出量。结果第1组铸造冠与其余2组的边缘浮出量差异有显著性(P<0.05)。其余2组间的边缘浮出量差异无显著性(P>0.05)。结论Dentaurum包埋材料与Dentaurum NiCrMo合金有良好的匹配性,与其余2种合金匹配其边缘浮出量也在临床允许范围内。     

3种烤瓷铸造合金的离子析出研究

目的 研究3种常用烤瓷非贵金属合金模拟烤瓷前、后在体外细胞培养液中离子析出的量及种类。方法 用失蜡法铸造3种常用烤瓷非贵金属合金试件,镍铬合金、钴铬合金、镍钛合金,置于DMEM体外细胞培养液中30 d后重新打磨,模拟烤瓷加热过程,之后放回DMEM体外细胞培养液中浸泡30 d,用电感耦合等离子发射光谱法(ICP-AES)观察烤瓷处理前、后3种合金离子的析出的改变,扫描电镜(SEM)对表面形态观察。结果 (1)3种合金离子析出总量依次为镍铬合金>钴铬合金>镍钛合金,(2)模拟烤瓷程序后3种合金离子析出总量减少,差异具有统计学意义(P<0.05)。结论 3种常用烤瓷非贵金属合金中,镍铬合金的离子析出量最大,生物相容性最差;烤瓷过程会促进这3种合金表面氧化膜的生成,使合金的耐腐蚀性有所增强。     

Biocompatibility effects of indirect exposure of base-metal dental casting alloys to a human-derived three-dimensional oral mucosal model

Objectives

The study employed a three-dimensional (3D) human-derived oral mucosal model to assess the biocompatibility of base-metal dental casting alloys ubiquitous in fixed prosthodontic and orthodontic dentistry.

Methods

Oral mucosal models were generated using primary human oral keratinocyte and gingival fibroblast cells seeded onto human de-epidermidised dermal scaffolds. Nickel–chromium (Ni–Cr) and cobalt–chromium (Co–Cr) base-metal alloy immersion solutions were exposed to oral mucosal models for increasing time periods (2–72 h). Analysis methodologies (histology, viable cell counts, oxidative stress, cytokine expression and toxicity) were performed following exposure.

Results

Ni-based alloy immersion solutions elicited significantly decreased cell viability (P < 0.0004) with increased oxidative stress (P < 0.0053), inflammatory cytokine expression (P < 0.0077) and cellular toxicity levels (P < 0.0001) compared with the controls. However, the Ni-free Co–Cr-based alloy immersion solutions did not elicit adverse oxidative stress (P > 0.4755) or cellular toxicity (P < 0.2339) responses compared with controls.

Conclusions

Although the multiple analyses highlighted Ni–Cr base-metal alloy immersion solutions elicited significantly detrimental effects to the oral mucosal models, it was possible to distinguish between Ni–Cr alloys using the approach employed. The study employed a 3D human-derived full-thickness differentiated oral mucosal model suitable for biocompatibility assessment of base-metal dental casting alloys through discriminatory experimental parameters.

Clinical significance

Increasing incidences of Ni hypersensitivity in the general population warrants serious consideration from dental practitioners and patients alike where fixed prosthodontic/orthodontic dental treatments are the treatment modality involved. The novel and analytical oral mucosal model has the potential to significantly contribute to the advancement of reproducible dental medical device and dental material appraisals.     

纤维桩和金属铸造桩修复疗效的回顾性比较

目的比较纤维桩和金属铸造桩在前牙和前磨牙残冠残根修复中的临床疗效。方法选择2009年至2010年我科门诊治疗中因残冠残根而行桩核冠修复的196例(262颗患牙)病例,以纤维桩作冠修复,门诊随访24个月,并与我科2007年至2008年211例(278颗患牙)对金属铸造桩作冠修复的研究结果作比较,观察两种桩核材料的临床疗效。结果经24个月的随访,纤维桩的成功率为95.42%,金属铸造桩的成功率为88.13%,两组之间的差异有统计学意义(P<0.05)。纤维桩的失败病例中均为冠折或桩核脱落。结论在前牙和前磨牙桩核冠修复中使用纤维桩的临床疗效优于金属铸造桩核,且纤维桩失败后可以进行二次修复,以达到保留患牙的目的。     

Image contrast range for detection of enamel defects using a digital dental imaging system

The purpose of this study was to quantitatively assess the acceptable range of image contrast for the detection of enamel defects by adjusting the contrast and brightness of a digital dental imaging system. Extracted human premolars and molars with enamel defects on the proximal surfaces were mounted in maxillary and mandibular sets on phantoms. The phantoms were individually exposed and processed with a digital dental imaging system from Computed Dental Radiography (CDR, Schick Technologies, Inc., NY, USA). The images were transferred to a personal computer, and the contrast and brightness were determined in the range of ±100 digital digit numbers (DDN) using Adobe Photoshop 4.0.1 J (Adobe Systems Inc., Tokyo, Japan). The 8-bit CRT display used was set at maximum inherent brightness. The relationship between the pixel value and the DDN in contrast at both the enamel and the background on the monitor was used to measure the acceptable image contrast by manipulating contrast and brightness. Six dental radiologists were asked to determine the presence or absence of enamel defects. The detectability was statistically analyzed using Fisher's protected limited standard deviation (PLSD) non-parametric test. When the inherent brightness on an 8-bit CRT display was adjusted to the maximum, there was an acceptable range of image contrast and brightness for the detection of enamel defects with this digital dental imaging system.     

Fabrication of a metal-ceramic crown to fit an existing partial removable dental prosthesis using ceramic pressed to metal technique: a clinical report

Fabricating a crown to retrofit an existing abutment tooth for a partial removable dental prosthesis (PRDP) is one of the most time-consuming and labor-intensive clinical procedures. In particular, when the patient is concerned with esthetic aspects of restoration, the task of fabricating becomes more daunting. Many techniques for the fabrication of all-metallic or metal-ceramic crowns have been discussed in the literature. This article was aimed to describe a simple fabrication method in which a retrofitting crown was fabricated for a precise fit using a ceramic-pressed-to-metal system.