3种非贵金属烤瓷合金的耐蚀性研究

目的 研究钴铬(Co-Cr)、镍铬(Ni-Cr)、镍铬铍(Ni-Cr-Be)3种非贵金属烤瓷合金在氯化钠溶液中的电化学腐蚀行为.方法 铸造Co-Cr、Ni-Cr、Ni-Cr-Be 3种烤瓷合金的试件各5个,采用动电位极化法绘制合金的电极化曲线,测定合金的自腐蚀电位(Ecorr)、自腐蚀电流密度(Icorr)、钝化区间以...     

飞行时间质谱仪监测甲基丙烯酸甲酯释放初探

目的 通过飞行时间质谱仪对自凝树脂聚合反应的全过程进行连续监测,动态分析甲基丙烯酸甲酯(methyl methacrylate,MMA)的变化趋势,以期为临床操作提供指导.方法 按生产厂家要求的比例将自凝义齿基托树脂粉剂2 g和液剂1 g调拌40 s后,即刻用飞行时间质谱仪连续监测MMA释放量,共监测5个样本.结果 MMA释放量在调拌后11 min时快速增加[(45.2±3.5)mg/L],13 min时达高峰[(228.9±22.6)mg/L];23 min时趋于稳定[(8.8±2.3)mg/L].结论 飞行时间质谱仪可连续监测自凝义齿基托树脂的聚合过程,精确地分析MMA释放量的变化趋势.结果 显示自凝义齿基托树脂聚合反应的MMA释放量变化较快.

Abstract：

Objective To analyze the amount and tendency of methyl methacrylate(MMA) released from autopolymerized denture base polymer (self-curing resin) during processing using time-of-flight mass spectrometer(TOF-MS). Methods Self-curing resin was mixed in the container using a ratio of 2 g of powder to 1 g of liquid in accordance with the manufacturer's instructions for 40 s as a specimen. The amount of MMA released from the specimen was continuously monitored and simultaneously recorded every minute by TOF-MS since immediately after mixing. A total of five specimens were monitored. Results The amount of MMA increased dramatically at 11 min[(45.2 ±3.5) mg/L] after mixing, and reached the highest level at 13 min[(228.9 ±22.6) mg/L], then become stable at 23 min[(8.8 ±2. 3) mg/L] after mixing. Conclusions The releasing tendency of MMA could be analyzed accurately with continuously monitoring during processing. The amount of MMA released from self-curing resin changed rapidly and the processing was complicated and changeful.     

3种临床常用烤瓷合金对小鼠成纤维细胞L929的毒性评价

目的:评价3种临床常用牙科烤瓷合金材料的细胞毒性.方法:采用一种能快速评定细胞增殖率和细胞毒性的CCK-8比色法,检测镍铬合金(Ni,77.36%)、钴铬合金(Co,61.0%)、金合金(Au,58.0%)等3种烤瓷合金材料对小鼠成纤维细胞L929相对增殖率的影响;应用单细胞凝胶电泳(彗星电泳),检测3种烤瓷合金材料对小鼠成纤维细胞L929 DNA的损伤情况.采用SAS9.0软件包对数据进行统计学分析.结果:镍铬合金组、钴铬合金组和金合金组细胞的相对增殖率分别为(75.9510±7.6244)%、(84.8920±8.2660)%和(88.5420±12.3611)%.镍铬合金组的细胞毒性显著高于钴铬合金组(P＜0.05)和金合金组(P＜0.05),而钴铬合金组与金合金组之间无显著差异(P＞0.05),但3种材料的细胞毒性分级均为1级,表现为轻微毒性;镍铬合金组DNA损伤程度的彗星数目显著高于钴铬合金组(P＜0.05)和金合金组(P＜0.05).而钴铬合金组与金合金组无显著差异(P＞0.05).结论:钴铬烤瓷合金材料的细胞毒性显著低于镍铬烤瓷合金材料,而与58%金烤瓷合金材料的细胞毒性接近.临床上应尽可能选择钴铬烤瓷合金或58%金烤瓷合金等细胞毒性较低的烤瓷合金材料.     

飞行时间质谱仪监测甲基丙烯酸甲酯释放初探

Objective To analyze the amount and tendency of methyl methacrylate(MMA) released from autopolymerized denture base polymer (self-curing resin) during processing using time-of-flight mass spectrometer(TOF-MS). Methods Self-curing resin was mixed in the container using a ratio of 2 g of powder to 1 g of liquid in accordance with the manufacturer's instructions for 40 s as a specimen. The amount of MMA released from the specimen was continuously monitored and simultaneously recorded every minute by TOF-MS since immediately after mixing. A total of five specimens were monitored. Results The amount of MMA increased dramatically at 11 min[(45.2 ±3.5) mg/L] after mixing, and reached the highest level at 13 min[(228.9 ±22.6) mg/L], then become stable at 23 min[(8.8 ±2. 3) mg/L] after mixing. Conclusions The releasing tendency of MMA could be analyzed accurately with continuously monitoring during processing. The amount of MMA released from self-curing resin changed rapidly and the processing was complicated and changeful.     

不同金属烤瓷全冠对龈沟液内可溶性细胞间黏附分子-1及白细胞介素-1β水平的影响

目的 通过对不同内冠金属材料的烤瓷熔附金属(PFM)全冠修复后龈沟液(GCF)内可溶性细胞间黏附分子-1 (sICAM-1)及白细胞介素-1β(IL-1β)水平的测定,探讨内冠金属材料对牙周组织的影响.方法 将30颗牙分为镍铬合金组、钴铬合金组和金铂合金组,每组10颗,分别进行镍铬合金、钴铬合金和金铂合金PFM全冠修复...     

镍铬合金与金铂合金烤瓷熔附金属全冠对犬牙龈组织的形态学影响

目的:比较镍铬合金和金铂合金2 种烤瓷熔附金属全冠(porcelain fused to metal,PFM)对犬牙龈组织结构的影响,观察PFM修复术的生物学效果,为临床上选择烤瓷熔附金属材料提供参考.方法:将3 只健康犬以镍铬合金和金铂合金2 种PFM修复犬牙,通过光镜和透射电镜观察犬牙龈组织的结构,用TUNEL方法检测细胞凋亡,并进行统计学分析.结果:镍铬合金PFM修复犬的牙龈组织,光镜下可见大量的炎性细胞浸润,局部血管出血;电镜下有大量细胞凋亡,凋亡指数为58.63%±11.12%,有细胞核固缩等反应.金铂合金PFM修复犬的牙龈组织光镜下未见大量的炎性细胞浸润及局部血管出血;电镜下少有细胞凋亡;凋亡指数为(26.90±17.35)%.统计分析显示镍铬合金PFM组和金铂合金PFM组的凋亡数与对照组都具有统计学意义,镍铬合金PFM组和金铂合金PFM组细胞凋亡数量有明显差异(P<0.05),镍铬合金组凋亡指数高.结论:镍铬合金PFM对犬牙龈组织结构的影响大,而金铂合金PFM对犬牙龈组织结构的影响小.临床PFM修复时,尽可能选择金铂合金制作PFM基底冠.     

两种热处理方式对激光焊接钴铬-镍铬异种合金力学性能和组织结构的影响

探讨常规热处理和烤瓷对激光焊接钴铬-镍铬异种合金力学性能和组织结构的影响,以期为异种合金的临床应用提供参考.方法将0.5 mm厚的钴铬合金和镍铬合金试件各15个从中间断开,进行激光焊接,制成30个钴铬-镍铬异种合金焊件.焊后用随机数字表将焊件随机分为3组,每组10个.对照组不做处理,热处理组焊件进行常规热处理,烤瓷组焊件进行烤瓷处理.测试3组焊件的拉伸强度和延伸率,扫描电镜观察拉伸断口,能谱分析测试3组焊件熔焊区、钴铬焊接交界区和镍铬焊接交界区元素.结果经热处理和烤瓷处理后,焊件拉伸强度分别为(537.15±43.91)MPa和(534.58±48.47)MPa,延伸率分别为(7.65±0.73)%和(7.40±0.45)%.烤瓷组拉伸断口出现明显的韧窝结构,热处理组拉伸断口表现为深而大的韧窝;钴铬侧合金成分向熔焊区和镍铬侧有一定程度的扩散,热处理组比烤瓷组扩散更明显.结论热处理和烤瓷过程均可在一定程度上改善激光焊接钴铬-镍铬异种合金焊接接头的性能,热处理对焊接接头性能的改善比烤瓷更明显.     

钴铬、镍铬、含钛镍铬烤瓷合金在人工唾液中耐腐蚀性能的比较

目的:评价钴铬、镍铬、含钛镍铬烤瓷合金在人工唾液中的耐腐蚀性能。方法:采用动电位极化曲线法测定钴铬、镍铬、含钛镍铬烤瓷合金试件的自腐蚀电流密度、极化电阻、自腐蚀电位,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、后试件表面的形貌变化。采用SPSS11.0软件包对数据进行单因素方差分析。结果:钴铬合金试件自腐蚀电流密度显著低于镍铬合金(P<0.05)及含钛镍铬合金(P<0.05);含钛镍铬合金试件自腐蚀电流密度低于镍铬合金(P<0.05)。钴铬合金试件的极化电阻显著高于镍铬合金(P<0.05)及含钛镍铬合金(P<0.05);含钛镍铬合金试件的极化电阻明显高于镍铬合金(P<0.05)。钴铬合金试件的自腐蚀电位高于镍铬合金(P<0.05)及含钛镍铬合金(P>0.05);含钛镍铬合金试件的自腐蚀电位高于镍铬合金(P>0.05)。FSEM显示,钴铬合金试样表面腐蚀较镍铬合金及含钛镍铬合金轻微。结论:钴铬烤瓷合金的耐腐蚀性优于镍铬烤瓷合金及含钛镍铬烤瓷合金,含钛镍铬烤瓷合金耐腐蚀性不及镍铬烤瓷合金。     

金沉积复合镍铬合金烤瓷的镍离子析出量的实验研究

目的 通过测试浸泡在人工唾液中的金沉积片复合镍铬合金片烤瓷试件的镍离子析出量,探究金沉积基底冠熔结镍铬桥体烤瓷桥是否能减少镍离子析出,降低生物安全风险.方法 将镍铬合金片与金沉积片粘接,表面烤瓷,瓷层厚度分别为0.3 mm(A组)、0.5 mm(B组)、1.0 mm(C组)和0.3 mm(D组),每组6个试件.对照组为镍铬合金片.A、B、C组和对照组浸泡在37℃酸性人工唾液中;D组浸泡在37℃酸性高氟人工唾液中.浸泡120 h后,测定浸泡液的镍离子浓度.独立样本t检验比较A～D组浸泡液镍离子浓度与对照组的差异.结果 A、B、C、D组的镍离子浓度均小于0.005 mg/L;与对照组[(0.65±0.45)mg/L]相比,差异均有统计学意义(P＜0.05).结论 金沉积基底冠熔结镍铬桥体烤瓷桥可减少镍离子析出,降低生物安全风险.     

镍铬合金烤瓷修复体拆除前后患者尿和血清中镍铬含量的评估

目的 通过测定镍铬合金烤瓷修复体拆除前后患者尿和血清中的镍铬含量,对镍铬合金的临床应用安全性进行科学评估.方法 选择因怀疑镍铬合金烤瓷修复体的镍、铬元素对全身有影响,主动要求拆除修复体的患者86例,于修复体拆前、拆后1个月采用石墨炉原子吸收光谱法检测患者尿镍、铬含量(86例)和血清镍、铬含量(69例).结果 镍铬烤瓷修复体拆除前后86例患者尿镍含量分别为(3.52±3.05)和(3.31 ±3.28) μg/L,尿铬含量分别为(0.81±0.54)和(1.34±1.15) μg/L;修复体拆除前后69例患者血清镍含量分别为(2.04±1.06)和(2.67±2.32) μg/L,血清铬含量分别为(1.07±0.88)和(1.02±0.86) μg/L;拆除前后差异均无统计学意义(P＞0.05).结论 本项研究条件下镍铬合会烤瓷修复体释放的镍、铬离子量微小,不足以对人体尿液及血液中的镍、铬含量造成影响.     

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。     

Effects of chemical composition on the corrosion of dental alloys

The aim of this study was to determine the effect of the oral environment on the corrosion of dental alloys with different compositions, using electrochemical methods. The corrosion rates were obtained from the current-potential curves and electrochemical impedance spectroscopy (EIS). The effect of artificial saliva on the corrosion of dental alloys was dependent on alloy composition. Dissolution of the ions occurred in all tested dental alloys and the results were strongly dependent on the general alloy composition. Regarding the alloys containing nickel, the Ni-Cr and Ni-Cr-Ti alloys released 0.62 mg/L of Ni on average, while the Co-Cr dental alloy released ions between 0.01 and 0.03 mg/L of Co and Cr, respectively.The open-circuit potential stabilized at a higher level with lower deviation (standard deviation: Ni-Cr-6Ti = 32 mV/SCE and Co-Cr = 54 mV/SCE). The potenciodynamic curves of the dental alloys showed that the Ni-based dental alloy with >70 wt% of Ni had a similar curve and the Co-Cr dental alloy showed a low current density and hence a high resistance to corrosion compared with the Ni-based dental alloys. Some changes in microstructure were observed and this fact influenced the corrosion behavior for the alloys. The lower corrosion resistance also led to greater release of nickel ions to the medium. The quantity of Co ions released from the Co-Cr-Mo alloy was relatively small in the solutions. In addition, the quantity of Cr ions released into the artificial saliva from the Co-Cr alloy was lower than Cr release from the Ni-based dental alloys.     

口腔内3种合金共存下的离子析出及表面粗糙度的改变

目的：研究口腔内3种合金共存下的离子析出及表面粗糙度的改变,为临床合金修复材料的选择提供参考。方法：制作镍铬合金、钴铬合金和金银钯合金标准试件,分为镍铬合金（N组）、钴铬合金（C组）、金银钯合金（A组）、镍铬合金与金银钯合金（NA组）和镍铬合金与钴铬合金（NC组）5组。浸泡于标准电解质溶液（T=37 ℃,pH=2.31）中,每组平行重复4次。7 d后,用电感耦合等离子体质谱仪检测各组浸提液中离子析出量;用原子力显微镜观察各组试件表面形貌,测量表面粗糙度。采用SPSS 18.0软件包对数据进行统计学分析。结果：析出的镍离子量N组为（1.32±0.03） μg/cm², NA组为(2.13±0.07) μg/cm²,NC组为(1.53±0.08) μg/cm²,NA组、NC组均显著多于N组,NA组显著多于NC组（P<0.05）;析出的铬离子量N组为(0.06±0.01) μg/cm²,NA组为(0.08±0.01) μg/cm²,NC组为(0.05±0.01) μg/cm²,NA组显著多于NC组（P<0.05）。镍铬合金的表面粗糙度N组为(4.60±0.16) nm,NA组为(5.37±0.08) nm,NC组为(5.04±0.15) nm,NA组、NC组均显著大于N组,NA组显著大于NC组（P<0.05）。镍铬合金与金银钯合金或钴铬合金共存时,析出的镍离子量比其单独使用时明显增多,其表面粗糙度明显增大;镍铬合金与金银钯合金共存时比镍铬合金与钴铬合金共存时析出的镍、铬离子量多,镍铬合金的表面粗糙度也大。结论：临床上应尽量避免在患者口腔内同时应用镍铬合金与金银钯合金,或镍铬合金与钴铬合金,尽量避免贱金属的临床使用。     

Use of x-ray photoelectron spectroscopy and cyclic polarization to evaluate the corrosion behavior of six nickel-chromium alloys before and after porcelain-fused-to-metal firing

STATEMENT OF PROBLEM: Nickel-chromium casting alloys rely on a surface oxide layer for corrosion resistance to the oral environment. Porcelain-fused-to-metal (PFM) firing procedures may alter the surface oxides and corrosion properties of these alloys. Changes in alloy corrosion behavior affect metal ion release and therefore local and/or systemic tissue responses. PURPOSE: The aim of this study was to evaluate changes in alloy surface oxides and electrochemical corrosion properties after PFM firing. MATERIAL AND METHODS: The electrochemical corrosion behavior of 6 commercial nickel-chromium alloys was evaluated in the as-cast/polished and PFM fired/repolished states. Surface chemistries of the alloys were analyzed by x-ray photoelectron spectroscopy. RESULTS: Results indicated an increase in corrosion rates after PFM firing and repolishing for alloys containing 14% to 22% Cr and 9% to 17% Mo. This increase in corrosion rates was attributed to a decrease, caused by the PFM and repolishing process, in the Cr and Mo levels in the surface oxides of these alloys. The PFM firing and repolishing process did not alter the corrosion behavior of the alloys containing lower levels of Cr and Mo and/or Be additions in their bulk composition. These alloys exhibited low levels of Cr and Mo surface oxides in both test conditions. Si particles became embedded in the surfaces of the fired alloys during repolishing and may have contributed to the changes in surface oxides and the corrosion behavior of some alloys. CONCLUSION: The effects of PFM firing and repolishing on Ni-Cr dental casting alloy surface oxides and corrosion properties appear to be alloy dependent.     

Corrosion behaviour and surface analysis of a Co-Cr and two Ni-Cr dental alloys before and after simulated porcelain firing

This study evaluated the corrosion behaviour and surface properties of a commercial cobalt-chromium (Co-Cr) alloy and two nickel-chromium (Ni-Cr) alloys [beryllium (Be)-free and Be-containing] before and after a simulated porcelain-firing process. Before porcelain firing, the microstructure, surface composition and hardness, electrochemical corrosion properties, and metal-ion release of as-cast alloy specimens were examined. After firing, similar alloy specimens were examined for the same properties. In both as-cast and fired conditions, the Co-Cr alloy (Wirobond C) showed significantly more resistance to corrosion than the two Ni-Cr alloys. After firing, the corrosion rate of the Be-free Ni-Cr alloy (Stellite N9) increased significantly, which corresponded to a reduction in the levels of Cr, molybdenum (Mo), and Ni in the surface oxides and to a reduction in the thickness of the surface oxide film. The corrosion properties of the Co-Cr alloy and the Be-containing Ni-Cr alloy (ChangPing) were not significantly affected by the firing process. Porcelain firing also changed the microstructure and microhardness values of the alloys, and there were increases in the release of Co and Ni ions, especially for Ni from the Be-free Ni-Cr alloy. Thus, the corrosion rate of the Be-free Ni-Cr alloy increased significantly after porcelain firing, whereas the firing process had little effect on the corrosion susceptibility of the Co-Cr alloy and the Be-containing Ni-Cr alloy.     

Metallurgical, surface, and corrosion analysis of Ni-Cr dental casting alloys before and after porcelain firing.

OBJECTIVES: A porcelain veneer is often fired on nickel-chromium casting alloys used in dental restorations for aesthetic purposes. The porcelain-fused-to-metal (PFM) process brings the temperature to over 950 degrees C and may change the alloy's corrosion properties. In this study, the metallurgical, surface, and corrosion properties of two Ni-Cr alloys were examined, before and after PFM firing. METHODS: Two types of alloy were tested-a high Cr, Mo alloy without Be and a low Cr, Mo alloy with Be. Before the PFM firing, specimens from both alloys were examined for their microstructures, hardness, electrochemical corrosion properties, surface composition, and metal ion release. After the PFM firing, the same specimens were again examined for the same properties. RESULTS: Neither of the alloys showed any differences in their electrochemical corrosion properties after the PFM firing. However, both alloys exhibited new phases in their microstructure and significant changes in hardness after firing. In addition, there was a slight increase in CrO(x) on the surface of the Be-free alloy and increased Mo-Ni was observed on the surface of both alloys via X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). This might be one of the reasons why both alloys had increased Ni and Mo ion release after firing. SIGNIFICANCE: The PFM firing process changed the alloys' hardness, microstructure, and surface composition. No significant changes in the alloys' corrosion behavior were observed, however, the significant increase in metal ion release over a month may need to be further investigated for its clinical effects.     

五种全冠合金铸造后的腐蚀性研究

目的 测定五种制作全冠的合金铸造后在体外细胞培养液中析出金属离子的种类及不同时间段析出的各种金属离子的量。方法 本实验用电感藕荷等离子质谱仪（ICP－MS）定量测定金属离子测试。结果 镍铬合金和钴铬合金析出离子最多银钯合金和钯合金有一定的金属离子析出，纯钛只析出微量钛离子。结论 纯钛、钯合金的耐腐蚀性最好，银钯合金次之，镍铬合金和钴铬合金的耐腐蚀性较差。     

纳米非晶金刚石膜镀覆对镍铬及钴铬烤瓷合金离子析出的影响

目的：观测纳米非晶金刚石膜对镍铬及钴铬两种非贵金属烤瓷合金在人工唾液中金属离子析出的影响。方法：制备镍铬合金、钴铬合金圆片形试件各24个,镍铬及钴铬合金试件随机分成a1、b1及a2、b2各两组,a1、a2组试件表面不镀膜,b1、b2组试件表面完整镀膜膜厚60nm,将a1、a2、b1、b2每组试件平分两半,分别置于pH值为6.8和4.0的人工唾液中浸泡7天,检测各组试件的金属离子析出量。结果：a1、a2组试件在两种人工唾液中表现出其所含各种金属离子的析出,在pH=4酸性人工唾液中浸泡后的离子析出量显著高于其在pH=6.8中性人工唾液中浸泡后的离子析出量（P〈0.05）;b1、b2组试件在两种人工唾液中浸泡后,其离子析出量分别比a1、a2组试件显著降低（P〈0.01）。结论：镍铬合金、钴铬合金在中性和酸性人工唾液中表现出其所含各种金属离子的析出,在酸性人工唾液中其金属离子析出量显著增加;纳米非晶金刚石镀膜能显著降低镍铬、钴铬合金在中性和酸性人工唾液中的金属离子析出量,有良好的耐腐蚀性。     

Elements released from dental casting alloys and their cytotoxic effects

PURPOSE: This in vitro study investigated the element release from seven commercially available dental casting alloys and tested their cytotoxic effects. MATERIALS AND METHODS: The casting alloys tested were one high-noble alloy (Bioherador N) and six base-metal alloys, including four Ni-Cr alloys (Remanium CS, Heranium NA, Wiron 99, CB Soft), one Co-Cr alloy (Wirobond C), and one Cu-based alloy (Thermobond). Ten specimens from each alloy were prepared in the form of disks, and each of the seven dental casting alloys (10 disks per group) were conditioned in distilled water at 37 degrees C for either 72 or 168 hours. The conditioning media were analyzed for element release, and the cytotoxic effects were assessed on Balb C fibroblasts using MTT assay. RESULTS: Element release was greater at 168 hours of conditioning than at 72 hours. The extract from the high-noble alloy showed the least amount of element release (only Zn), with no cytotoxic effects. The greatest amount of element release was detected in the Cu-based alloy Thermobond and the Ni-Cr alloy CB Soft; their extracts were significantly more toxic than all the other alloy extracts. The cytotoxic effects of the other Ni-Cr alloy extracts were not statistically significantly different from the high-noble alloy extract. However, the Co-Cr alloy (Wirobond C) extract was significantly more cytotoxic than the high-noble alloy extract. CONCLUSION: Element release from casting alloys is proportional to the conditioning time. The content of Cr and Mo in the alloy protects the alloy from dissolution, while the Cu content makes it more susceptible to corrosion and dissolution, rendering it more cytotoxic.     

Comparison of the bond strength of laser-sintered and cast base metal dental alloys to porcelain

OBJECTIVE: The purpose of this study was to compare shear bond strengths of cast Ni-Cr and Co-Cr alloys and the laser-sintered Co-Cr alloy to dental porcelain. METHODS: Dental porcelain was applied on two cast and one laser-sintered base metal alloy. Ten specimens were prepared for each group for bond strength comparison. ANOVA followed by Tukey HSD multiple comparison test (alpha=0.05) was used for statistical analysis. Fractured specimens were observed with a stereomicroscope to classify the type of failure after shear bond testing. RESULTS: While the mean shear bond strength was highest for the cast Ni-Cr metal-ceramic specimens (81.6+/-14.6MPa), the bond strength was not significantly different (P>0.05) from that for the cast Co-Cr metal-ceramic specimens (72.9+/-14.3MPa) and the laser-sintered Co-Cr metal-ceramic specimens (67.0+/-14.9MPa). All metal-ceramic specimens prepared from cast Ni-Cr and Co-Cr alloys exhibit a mixed mode of cohesive and adhesive failure, whereas five of the metal-ceramic specimens prepared from the laser-sintered Co-Cr alloy exhibited the mixed failure mode and five specimens exhibited adhesive failure in the porcelain. CONCLUSIONS: The new laser-sintering technique for Co-Cr alloy appears promising for dental applications, but additional studies of properties of the laser-sintered alloy and fit of castings prepared by this new technique are needed before its acceptance into dental laboratory practice. SIGNIFICANCE: Laser sintering of Co-Cr alloy seems to be an alternative technique to conventional casting of dental alloys for porcelain fused to metal restorations.