不同厚度氮化钛涂层对镍钛器械显微硬度及切削性能的影响

目的:探讨不同厚度氮化钛涂层对镍钛根管器械显微硬度及切削性能的影响,为提高临床根管预备效率提供依据.方法:选取15个KV4型镍钛合金片和60支25# KV4型机用镍钛锉,随机分为5组:未镀膜组、镀膜1h组、镀膜2h组、镀膜3h组和镀膜4h组.通过控制沉积时间,制备不同厚度的镍钛氮化钛涂层,扫描电镜(SEM)下测量每组的...     

Focal adhesion contact formation by fibroblasts cultured on surface-modified dental implants: an in vitro study

A major consideration in designing dental implants is to create a surface that provides strong attachment of the implant to bone, connective tissue and epithelium. The aim of the present study was to examine the influence of different treatments of titanium (Ti) implant surfaces on focal adhesion contact (FAC) formation in fibroblast cultures. Human gingival fibroblasts were cultured on glass sheets and polished Ti discs with different surface coatings (applied by physical vapor deposition (PVD): Ti, titanium nitride (TiN), zirconium nitride (ZrN)) or on Ti discs with different surface topographies. For characterization of all surfaces, modified estimation of surface roughness and spacing parameter was carried out using a contact stylus profilometer. Contact angle measurements were carried out to calculate surface energy. Fibroblasts were prepared for transmission electron microscopy at day 3 after seeding, and the number of FACs and the ratio FAC/cellular cross-sections was determined at a length of 300 microm in ultrathin sections. To visualize the extracellular fibronectin and vitronectin molecules and the intracellular actin and vinculin in FAC areas, immunogold labeling was performed. The results revealed a strong correlation between the number of FACs and the surface roughness. The highest number of FACs and the majority of the immunogold-labeled intra- and extracellular matrix molecules were counted on surfaces with the lowest surface roughness: glass sheets coated with either Ti, TiN or ZrN (roughness average=0.03-0.1 microm). These surfaces appear to favor cellular attachment of human gingival fibroblasts and moreover in previous studies the hard coatings have been shown to reduce bacterial adhesion.     

Shear bond strength of veneering composite resin to titanium nitride coating alloy deposited by radiofrequency sputtering

OBJECTIVE: The success of dental restorations utilizing composite resin over cast alloy has been variable and affected by micro-leakage. The purpose of this study was to investigate the shear bond strength between a composite resin and cast dental alloy coated with a layer of titanium nitride (TiN). METHODS: Cast disk specimens made of Au-Pd-Ag alloy were randomly divided into four groups. The first group was left uncoated as a control while one group was coated with a metal conditioner, and the other two were coated with TiN at either 200 or 500 W with a radiofrequency magnetron sputtering system. Each group was then bonded to one of two types of light-activated composite resin material. Shear bond strengths were tested and compared for each specimen. The bond strength of each group was analyzed by 2-way ANOVA and by post hoc multiple comparison tests (Fisher's PLSD). RESULTS: As the interaction among groups was not significant (p=0.27) by 2-way ANOVA, TiN coated groups were found to have improved shear bond strength compared with non-coated groups without metal conditioner for both resin composite materials by multiple comparison tests. Furthermore, TiN coating is significantly stronger than non-coated groups with metal conditioner for one of the two resin composite materials examined (p<0.01). CONCLUSIONS: The results suggested that metal surface modification by coated TiN represents a technique that may significantly improve the bond between the Au-Pd-Ag alloy and veneering resin composite.     

Influence of modifying and veneering the surface of ceramic abutments on cellular attachment and proliferation

Objectives: This in vitro study was aimed to investigate the attachment, spreading and proliferation of human gingival fibroblasts to milled and polished non‐veneered ceramic surfaces in alumina and zirconia and to ceramic surfaces veneered by two different types of porcelain baseliners. Materials and methods: Fibroblasts were cultured on discs of pressed alumina or zirconia, on discs which had been milled, on discs comprising alumina or zirconia which had been polished, on discs of alumina veneered with NobelRondo baseliner Al, on discs of zirconia veneered with Cercon‐S baseliner, and on alumina or zirconia discs veneered with the above baseliners and then polished. The surfaces were analyzed using an optical interferometer and scanning electron microscopy (SEM). Cell profile areas were measured using SEM and an image analyzer. Cell attachment was determined after 3 and 24 h as a ratio of the cell profiles and the total micrograph area and was expressed as percent of attachment. MTT analyses were undertaken to determine cellular attachment after 3 h of incubation and cellular proliferation after 7 days. Results: The polished zirconia specimens had the smoothest surface in terms of average height deviation (S_a=0.03 μm): the roughest were the zirconia specimens with milled surfaces (S_a=0.36 μm). The application of the baseliners resulted in surfaces smoother than those of the non‐veneered discs. The milled surfaces of both alumina and zirconia had significantly higher percentages of cell attachment and proliferation than the other surfaces whereas the milled surfaces in zirconia demonstrated better cellular attachment after 3 and 24 h of culture than the one in alumina. Fibroblasts attached and grew effectively on the surfaces veneered with NobelRondo throughout the experiments, whereas the zirconia surfaces veneered with Cercon‐S had the lowest percentage of cell attachment and proliferation. Conclusions: Although the roughness of all surfaces investigated was <0.4 μm, the study disclosed significant differences in cellular attachment and proliferation associated with the various surface modifications.     

Effects of base-metal casting alloys on cytoskeletal filaments in cultured human fibroblasts

PURPOSE: The present study was designed to determine the cytotoxic effects of some widely used dental base-metal casting alloys (Ni-Cr and Co-Cr) on the cytoskeleton in cultured human fibroblasts, and to evaluate whether any structural alteration is associated with the application of these alloys. MATERIALS AND METHODS: Ten specimens from six different alloys were prepared as 5-mm disks. Five of ten samples from each group were polished; the remaining five samples were left sandblasted with 50-microm Al2O3. All samples were directly exposed to human fibroblasts in a 24-well cell culture dish for 120 hours. Then, cells were fixed and stained with antibodies against major cytoskeletal elements--actin, vimentin, and microtubules--by immunofluorescent staining methods. Cells were analyzed in 3-D to document the cytoskeletal alterations using a laser confocal microscope. RESULTS: Disintegration of actin filaments was observed in lamellipodia of fibroblasts by the effect of both polished and sandblasted Ni-Cr and Co-Cr samples, with the exception of the polished Co-Cr alloy (Wirocast). Moreover, intracytoplasmic actin-decorated stress fibers were found bent and occasionally tangled in the sandblasted Ni-Cr (Wiron 99) and Co-Cr alloys (Wirocast and Co-Cr Degussa). Vimentin, a mesenchymal cell intermediate filament protein normally showing an intracellular meshwork pattern, was not affected by any of the polished or sandblasted alloys. Microtubules mainly remained intact in all dental alloy-treated groups. CONCLUSION: Taken together, it is possible to postulate that Ni-Cr and Co-Cr dental alloys, especially sandblasted forms, may have detrimental effects on the actin-based cytoskeleton, at least tested in vitro.     

氮化钛涂层对循环摘戴后套筒冠固位力的影响

目的:研究氮化钛涂层对循环摘戴后圆锥型套筒冠固位力的影响.方法:使用精密数控车床制作标准金属内、外冠试件14 对,随机分成2 组(实验组和对照组),每组7 对,在实验组套筒冠内冠表面和外冠内面沉积2 μm氮化钛(TiN),未镀TiN组为对照组,测定2 组套筒冠经循环摘戴后固位力值.采用SPSS 13.0软件包对实验数据进行成组t检验统计分析.结果:镀TiN组套筒冠初始固位力较未镀膜组小, 2 组固位力随循环次数的增加而降低,未镀膜组固位力下降速度较镀膜组更为显著.镀TiN组套筒冠在循环3 000 次后固位力开始下降,3 000 次前和7 000 次后固位力下降平缓.结论:圆锥型套筒冠内、外冠沉积氮化钛涂层可以降低套筒冠固位力衰减速度,能够保持持久的固位力.     

Plaque formation on surface modified dental implants

Bacterial adhesion on titanium implant surfaces has a strong influence on healing and long-term outcome of dental implants. Parameters like surface roughness and chemical composition of the implant surface were found to have a significant impact on plaque formation. The purpose of this study was to evaluate the influence of two physical hard coatings on bacterial adhesion in comparison with control surfaces of equivalent roughness. Two members of the oral microflora, Streptococcus mutans and Streptococcus sanguis were used. Commercially pure titanium discs were modified using four different surface treatments: physical vapour deposition (PVD) with either titanium nitride (TiN) or zirconium nitride (ZrN), thermal oxidation and structuring with laser radiation. Polished titanium surfaces were used as controls. Surface topography was examined by SEM and estimation of surface roughness was done using a contact stylus profilometer. Contact angle measurements were carried out to calculate surface energy. Titanium discs were incubated in the respective bacterial cell suspension for one hour and single colonies formed by adhering bacteria were counted by fluorescence microscopy. Contact angle measurements showed no significant differences between the surface modifications. The surface roughness (Ra) of all surfaces examined was between 0.14 and 1.00 microm. A significant reduction of the number of adherent bacteria was observed on inherently stable titanium hard materials such as TiN and ZrN and thermically oxidated titanium surfaces compared to polished titanium. In conclusion, physical modification of titanium implant surfaces such as coating with TiN or ZrN may reduce bacterial adherence and hence improve clinical results.     

Crystal structure of zirconia affects osteoblast behavior

ObjectivesDifferent approaches are currently undertaken to structure the endosseous part of zirconia implants. The purpose of the present study was to evaluate how surface roughness and monoclinic to tetragonal phase ratio of zirconia affect cell behavior of human osteoblasts.MethodsZirconia discs with five different surface structures were produced: machined; machined heat-treated; polished; polished heat-treated; sandblasted, etched and heat-treated (cer.face 14, vitaclinical). The specimen surfaces were then characterized in terms of monoclinic to tetragonal phase ratio, wettability, roughness and visualized using scanning electron microscopy. To determine the reaction of the human osteoblastic cells (MG-63) to the surface roughness and monoclinic to tetragonal phase ratio of zirconia, cell spreading, morphology, actin cytoskeleton, viability and gene expression of alkaline phosphatase (ALP), collagen type I (COL) and osteocalcin (OCN) were assessed.ResultsHeat-treatment of the specimens significantly improved the surface wettability. With increased surface roughness Ra of the specimens, cell spreading was reduced. Cell viability after 24 h correlated linearly with the tetragonal phase ratio of the specimens. Gene expression after 24 h and 3 d was comparable on all specimens irrespective their surface roughness or monoclinic to tetragonal phase ratio.SignificanceSmooth zirconia surfaces with a high tetragonal phase ratio revealed best surface conditions for MG-63 osteoblastic cells and may be considered to design the endosseous part of zirconia implants.     

An investigation of the cytotoxic effects of dental casting alloys

PURPOSE: This study investigated the cytotoxicity of a high-noble alloy (Bioherador N) and six commercially available 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). MATERIALS AND METHODS: Ten specimens from each alloy were prepared in the form of disks, which were placed in 24-well tissue culture plates together with a suspension containing Balb/C 3T3 fibroblasts (5 x 10(5) cells/mL). After 3 days of incubation at 37 degrees C, cell viability was determined by the MTT method. RESULTS: Variations in cytotoxicity of the alloys were observed and related to their composition. One-way ANOVA showed statistically significant differences in cytotoxicity of the alloys (P < .001). Tukey's multiple comparisons (alpha = .05) revealed that Bioherador N was significantly less cytotoxic than all the other alloys. Thermobond was the most cytotoxic, followed by CB Soft, and both of these alloys were significantly more cytotoxic than all the others. CONCLUSION: The cytotoxicity of casting alloys tested in this study was markedly affected by their composition. Differences were found in the cytotoxicity of alloys classified within the same category. The presence of Cu in the composition of the alloy adversely affected cell viability.     

两种表面改性方法对钴-铬合金化学腐蚀行为的影响

目的研究钴-铬合金表面镀氮化钛薄膜和镀金薄膜后对其化学腐蚀行为的影响。方法利用多弧离子镀和电镀方法分别在钴-铬合金表面沉积氮化钛和金薄膜,将两种镀膜和未镀膜试件分别浸入人工唾液,在37℃恒温下浸泡,在第30、60、90天定量取浸泡的人工唾液10 ml,采用原子吸收光谱法测定唾液中的钴离子含量,浸泡结束后,检测试件的重量变化。结果在3个时间点,镀氮化钛试件释出的钴离子量都显著小于镀金和未镀膜组,镀氮化钛组和未镀膜组试件浸泡前后的失重量显著小于镀金组。结论在钴-铬合金表面镀氮化钛膜可显著减少金属离子释出,提高其耐腐蚀性能,效果可靠,优于镀金。     

镍铬合金氮化钛涂层对白色假丝酵母菌粘附性和耐腐蚀性影响的研究

目的:通过研究牙用镍铬合金表面氮化前后白色假丝酵母菌粘附量的变化和耐电化学腐蚀的变化为镍铬合金表面改性的应用提供理论基础。方法:采用真空镀膜技术在镍铬合金片表面沉积氮化钛薄膜,用菌落计数法测定和比较镀膜前后白色假丝酵母菌的粘附量有无差异;采用动电位极化曲线法,比较在PH6.8的人工唾液中,镍铬合金镀膜前后极化曲线的差异,应用场扫描电镜观测腐蚀后试件表面的破坏程度。结果:镍铬合金表面氮化后,白色假丝酵母菌粘附量明显减少,差别具有统计学意义;电化学实验显示,镀膜组极化曲线向正方向移位。结论:镍铬合金表面镀膜能抑制白色假丝酵母菌的粘附同时提高耐腐蚀性能。     

The effect of two fibre impregnation methods on the cytotoxicity of a glass and carbon fibre-reinforced acrylic resin denture base material on oral epithelial cells and fibroblasts

Acrylic resin dentures may have cytotoxic effects on oral soft tissues. However, there is sparse data about the cytotoxic effect of fibre-reinforced acrylic resin denture base materials. The purpose of this in vitro study was to determine the effect of two fibre impregnation methods on the cytotoxicity of a glass and carbon fibre-reinforced heat-polymerized acrylic resin denture base material on oral epithelial cells and fibroblasts. One hundred acrylic resin discs were assigned to five experimental groups (n = 20). One of the groups did not include any fibre. Two groups consisted of silane and monomer treated glass fibres (Vetrolex) impregnated into acrylic resin (QC-20) discs. The other two groups consisted of silane and monomer treated carbon fibres (Type Tenox J, HTA). Untreated cell culture was used as positive control. The human oral epithelial cell line and buccal fibroblast cultures were exposed to test specimens. The cytotoxicity of the test materials was determined by succinic dehydrogenase activity (MTT method) after 24 and 72 h exposures. Data were analysed with a statistical software program (SPSSFW, 9.0). A one-way analysis of variance (anova) test and Bonferroni test were used for the comparisons between the groups. All statistical tests were performed at the 0.95 confidence level (P < 0.05). After 24 and 72 h incubation, cell viability percentages of all experimental groups showed significant decrease according to the positive control cell culture. Fibroblastic cell viability percentages of silane and monomer treated fibre-reinforced groups were lower than the unreinforced group. Cell viability of monomer-treated groups displayed the lowest percentages. Elapsed incubation time decreased epithelial cell viability in silane-treated groups. Fibroblastic cell viability was not influenced by elapsed time except the unreinforced group.     

氮化钛纳米膜对磁性附着体铁铬钼合金磁力影响的研究

目的研究应用离子束辅助沉积制备氮化钛薄膜后,对磁性附着体磁力的影响.方法应用电子拉伸机测量镀膜前后磁性附着体磁力大小.结果镀膜前后磁性附着体磁力无明显改变,统计学分析无显著性差异(P>0.05).结论磁性附着体铁铬钼合金经表面镀膜后,磁力无改变.可以应用离子束辅助沉积技术对磁性附着体进行表面处理.     

自身上釉和抛光对瓷表面结构的影响

目的：通过扫描电镜观察和临床菌斑指数的检查,评价磨具打磨后版面知上釉和抛光对金瓷修复体瓷表面光洁度及其上菌斑聚集程度的影响,方法：实验分四组,每组按帝验条件用磨具将瓷表面处理,然后三组自身上釉,一组抛光,结果：扫描电镜观察见身上釉的三组样本瓷表面光洁度主瓷表面抛光组,瓷表面菌斑较少,结论：全身上釉可获得高 滑的瓷表面光洁度、菌斑附着少,而抛光使瓷表面较粗糙,菌斑聚集较多,可能会对牙龈组织有损害。     

Surface roughness of a dental amalgam via a laser scattering test

Laser scattering was investigated as an alternative, quantitative method for evaluating changes in the surface roughness of dental amalgam. Specimens of a conventional alloy were finished using one of the following techniques: a), carving; b), c), metallographic polishing done 1 and 24 h ater placement, respectively. Using a helium-neon laser and a computerized goniometer stage, the surface roughness of polished samples was measured after exposure either to air (0, 1, 2, 4, 24 h), or to 0.5% Na₂S (2 and 16 h). When exposed to air, the specimens polished 24 h after placement showed only slight changes in roughness over a 24 h period. In contrast, the samples polished 1 h after placement were always smoother, although their greatest increase in roughness occurred within 60 min of polishing. Although no statistically significant differences were noted between the 1 and 24 h polished specimens which were tarnished for 2 h, the 1 h polished samples were less tarnished than the 24 h polished samples after 16 h exposure.     

Cytotoxicity of a silorane-based dental composite on human gingival fibroblasts

AIM: To evaluate the direct and indirect biocompatibility of Filtek Silorane on human gingival fibroblastic cells. METHODS: Sixty-three standardized cylindrical specimens (8 mm diameter and 2 mm thickness) of restorative material were prepared using a light emitting diode-curing unit. The sample were built up in one increment and divided in 2 groups. In the first group, 21 samples (unpolished samples) were left without a specific polishing procedure; in the second one, 42 samples (polished samples) were polished with 4 different grains of discs. Fibroblast cultures, obtained from gingiva of 2 subjects without systemic and oral disease, were used to assess the direct and indirect biocompatibility. Cells cultured for 48 h in normal culture medium were used as a control. RESULTS: The scanning electron microscope observations of fibroblasts cultured on the silorane samples, either polished or unpolished, confirmed the good biocompatibility of the material, favouring the cellular spreading. 3-dimethylthiazol-2, 5-diphenyltetrazolium bromide tests showed a significant reduction (P < 0.01) of gingival fibroblasts viability cultured both in polished samples (90.05% ± 19.00%) and unpolished samples (78.15% ± 11.00%) compared with the control. Cells growth in medium conditioned with the samples for 1 wk showed a significant viability reduction (P < 0.01) compared to the control. A reduction of cell viability was observed even in the groups containing the material for 3 wk (polished: 89.45% ± 10.00%; unpolished: 65.97% ± 10.00%), even if the cytotoxicity was reduced after this long time exposure. CONCLUSION: Although the poor chromatic availability of this material remains a big limit that restricts its use to posterior sectors, the silorane-based material can be considered an option to perform restorations when aesthetic demands are not the priority, such as the class II restorations     

Bone healing around titanium and titanium nitride-coated dental implants with three surfaces: an experimental study in rats

Background: Titanium nitride (TiN) has been used in many fields as a coating of surgical instruments, with the purpose of creating materials more resistant to wear and corrosion and also reducing adhesion. Purpose: The aim of this study was to evaluate the biocompatibility of TiN‐coated dental implants. Materials and Methods: Forty‐five rats were used in this study. One hundred eighty 2 mm 2 mm implants (P.H.I., San Vittore Olona, Milano, Italy) were used. The implants were divided into the following three groups: Group 1 (n= 60):30 machined and 30 machined coated with TiN Group 2(n= 60):30 sandblasted and 30 sandblasted coated with TiN Group 3 (n= 60):30 titanium plasma sprayed, 30 titanium plasma sprayed and coated with TiN Four implants were placed in each rat, two implants coated with TiN on the right tibia and two uncoated implants on the left. The animals were killed after 5, 10, 20, 30, or 60 days. Another 18 implants were used for surface roughness analysis. Results: The present study showed that the healing around the TiN‐coated implants was similar to that observed around the uncoated surfaces. Conclusions: TiN coating demonstrated a good biocompatibility, did not have untoward effects on the periimplant bone formation, and did not change the surface roughness values.     

Adhesive bonding of titanium nitride-plated stainless steel for magnetic attachments

The purpose of this study was to evaluate adhesive bonding of resin to titanium nitride ion-plated stainless steel in order for magnetic attachments to survive in the oral environment. Two primers, Cesead II Opaque Primer (CPII) and Metal Primer II (MPII), and one bonding agent, Super-Bond C&B (SB), were used. The surfaces of stainless steel disks were ground and then plated with titanium nitride. After the primer and SB resin were applied, a self-curing resin was bonded to the metal surfaces. Shear bond strengths were determined after 24 h of water storage and after 2,000 thermocycles. Titanium nitride ion-plated stainless steel showed bond strength comparable to the non-plated material. After thermocycling, all specimens of the group no primer/no SB were debonded. The bond strengths of groups CPII/no SB, MPII/no SB and no primer/SB were significantly lower bond strengths than groups CPII/SB and MPII/SB. An appropriate combination of primer and bonding agent should be selected when bonding a magnetic attachment to the denture base.     

The influence of surface standardization of lithium disilicate glass ceramic on bond strength to a dual resin cement

In vitro studies to assess bond strength between resins and ceramics have used surfaces that have been ground flat to ensure standardization; however, in patients, ceramic surfaces are irregular. The effect of a polished and unpolished ceramic on bond strength needs to be investigated. Sixty ceramic specimens (20×5×2 mm) were made and divided into two groups. One group was ground with 220- to 2000-grit wet silicon carbide paper and polished with 3-, 1-, and ?-μm diamond paste; the other group was neither ground nor polished. Each group was divided into three subgroups: treated polished controls (PC) and untreated unpolished controls (UPC), polished (PE) and unpolished specimens (UPE) etched with hydrofluoric acid, and polished (PS) and unpolished specimens (UPS) sandblasted with alumina. Resin cement cylinders were built over each specimen. Shear bond strength was measured, and the fractured site was analyzed. Analysis of variance (ANOVA) and Tukey post hoc tests were performed. PE (44.47 ± 5.91 MPa) and UPE (39.70 ± 5.46 MPa) had the highest mean bond strength. PS (31.05 ± 8.81 MPa), UPC (29.11 ± 8.11 MPa), and UPS (26.41 ± 7.31 MPa) were statistically similar, and PC (24.96 ± 8.17 MPa) was the lowest. Hydrofluoric acid provides the highest bond strength regardless of whether the surface is polished or not.